WWTP 20260106_ BODR_10% Design_RBC Capital Upgrade and BiosolidsDigester Optimization Project Stamped_AMAR — Crescent City City Council, March 2, 2026 (part 1 of 2)

FOR
Crescent City
RBC Capital Upgrade and
Biosolids/Digester Optimization
Project
SUBMITTED:

January 6, 2026
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
Client name: City of Crescent City
Project name: RBC Capital Upgrade and Biosolids/Digester Optimization Project Document no: 250911112115_57ee610a Project manager: Barbara Andrade Version: Final Prepared by: Sheila Nilsen, Ana Arango, Massimo Romano, Christopher Lunsford, Michael
Molinari, Jason Hise, Anthony Fasano,
Michele McHenry, Mark Twede, Nick
Okudugha, Nate Ebbs, Scott Cowden
Date: January 2026 Client representatives: Eric Weir, David Yeager, Andrew Leighton, Martha Rice, Linda Leaver
Document History and Status
Version Date Author Reviewed Approved
00 9/23/2025 Sheila Nilsen, Ana Arango, Massimo
Romano, Christopher Lunsford
Barbara Andrade Jasmine Diaz
01 11/03/2025 Jasmine Diaz, Barbara Andrade, Carl
Koester, Ryujiro Tsuchihashi, Michelle
Melkonians, Sheila Nilsen, Ana Arango,
Massimo Romano, Christopher Lunsford,
Michael Molinari, Jason Hise, Anthony
Fasano, Michele McHenry, Mark Twede,
Nick Okudugha
Jasmine Diaz, Barbara
Andrade, Doug Barber,
Tom Johnson, Scott
Levesque, Nate Ebbs
Barbara Andrade
02 1/6/2026 Jasmine Diaz, Barbara Andrade, Carl
Koester, Ryujiro Tsuchihashi, Michelle
Melkonians, Sheila Nilsen, Ana Arango,
Massimo Romano, Christopher Lunsford,
Michael Molinari, Jason Hise, Anthony
Fasano, Michele McHenry, Mark Twede,
Nick Okudugha, Nate Ebbs, Scott Cowden
Sheila Nilsen, Olivia
Kalb, Kim Andretta
Barbara Andrade
Jacobs Engineering Group Inc.
2525 Airpark Drive
Redding, CA 96001-2443
United States
T +1.530.229.3225
F +1.530.243.1654
www.jacobs.com
© Copyright 2026 Jacobs Engineering Group Inc.. All rights reserved. The content and information contained in this document are the property of the Jacobs group of companies (“Jacobs Group”). Publication, distribution, or reproduction of this document in whole or in part without the written permission of Jacobs Group constitutes an infringement of copyright. Jacobs, the Jacobs logo, and all other Jacobs Group trademarks are the property of Jacobs Group.

NOTICE: This document has been prepared exclusively for the use and benefit of Jacobs Group client. Jacobs Group accepts no liability or responsibility for any use or reliance upon this document by any third party.

RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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Contents
Acronyms and Abbreviations........................................................................................................................................... i

1. Introduction ........................................................................................................................................................1-1

1.1 Project Description........................................................................................................................................... 1-1

1.1.1 Project Funding .................................................................................................................................... 1-2

1.1.2 Previous Reports .................................................................................................................................. 1-2

1.1.3 Project History....................................................................................................................................... 1-2

1.2 Project Location ................................................................................................................................................ 1-4

1.2.1 Relevant Hydrological, Geologic, and Topographic Features .............................................. 1-5

1.2.2 Tsunami Code Application................................................................................................................ 1-6

1.3 Existing Treatment Facilities......................................................................................................................... 1-9

1.3.1 National Pollutant Discharge Elimination System Permit Information...........................1-11

1.4 Project Schedule Update..............................................................................................................................1-15

1.4.1 Construction Sequencing................................................................................................................1-16

1.4.2 Class 4: Conceptual Estimate.........................................................................................................1-18

1.4.3 Environmental Considerations ......................................................................................................1-18

2. Flows and Loading Design Criteria ................................................................................................................2-1

2.1 Historical Flows and Loads............................................................................................................................ 2-1

2.2 Wastewater Flows ............................................................................................................................................. 2-1

2.2.1 Wastewater Treatment Facility Flow Analysis............................................................................ 2-1

2.3 Service Area........................................................................................................................................................ 2-2

2.3.1 Service Area Growth Projections..................................................................................................... 2-2

2.4 Design Flows and Loads ................................................................................................................................. 2-4

2.5 Plant Performance Evaluation...................................................................................................................... 2-5

2.6 Hydraulics............................................................................................................................................................ 2-6

3. Liquid Stream Improvements .........................................................................................................................3-1

3.1 Membrane Bioreactor ..................................................................................................................................... 3-3

3.1.1 Background............................................................................................................................................ 3-3

3.1.2 Process Description............................................................................................................................. 3-3

3.1.3 Design Criteria....................................................................................................................................... 3-4

3.1.4 Structural Improvements ................................................................................................................3-11

3.1.5 Instrumentation and Controls .......................................................................................................3-11

3.2 Attached Growth Treatment Facility........................................................................................................3-11

3.2.1 Background..........................................................................................................................................3-11

3.2.2 Design Criteria.....................................................................................................................................3-11 ii

3.2.3 Process Description...........................................................................................................................3-12

3.2.4 Structural Improvements ................................................................................................................3-13

3.2.5 Instrumentation and Controls .......................................................................................................3-13

3.3 Cloth Media Filtration ...................................................................................................................................3-13

3.3.1 Background..........................................................................................................................................3-13

3.3.2 Process Description...........................................................................................................................3-14

3.3.3 Design Criteria.....................................................................................................................................3-14

3.3.4 Structural Improvements ................................................................................................................3-17

3.3.5 Instrumentation and Controls .......................................................................................................3-18

4. Solids Handling Improvements......................................................................................................................4-1

4.1 Waste Activated Sludge and Digested Sludge Storage and Pump Gallery................................... 4-3

4.1.1 Process Description............................................................................................................................. 4-5

4.1.2 Design Criteria....................................................................................................................................... 4-5

4.1.3 Alternatives Discussion...................................................................................................................... 4-7

4.1.4 Instrumentation and Controls .......................................................................................................4-11

4.1.5 Pump Gallery HVAC and Odor Control.......................................................................................4-11

4.1.6 Structural Improvements ................................................................................................................4-12

4.1.7 Corrosion Control...............................................................................................................................4-12

4.2 Gravity Thickener............................................................................................................................................4-13

4.2.1 Background..........................................................................................................................................4-13

4.2.2 Design Criteria.....................................................................................................................................4-13

4.2.3 Rehabilitation Description ..............................................................................................................4-13

4.2.4 Instrumentation and Controls .......................................................................................................4-14

4.2.5 Corrosion...............................................................................................................................................4-14

4.3 Anaerobic Digestion.......................................................................................................................................4-14

4.3.1 Background..........................................................................................................................................4-14

4.3.2 Design Criteria.....................................................................................................................................4-15

4.3.3 Process Description...........................................................................................................................4-15

4.3.4 Digester Rehabilitation ....................................................................................................................4-15

4.3.5 Instrumentation and Controls .......................................................................................................4-18

4.3.6 Corrosion...............................................................................................................................................4-18

5. Additional Improvements................................................................................................................................5-1

5.1 Primary Clarifiers............................................................................................................................................... 5-1

5.1.1 Process Description............................................................................................................................. 5-1

5.1.2 Design Criteria....................................................................................................................................... 5-1

5.1.3 Process Description............................................................................................................................. 5-1 RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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5.1.4 Structural and Architectural Improvements............................................................................... 5-2

5.2 Grit Removal....................................................................................................................................................... 5-2

5.2.1 Process Description............................................................................................................................. 5-2

5.2.2 Design Criteria....................................................................................................................................... 5-2

5.3 Yard Piping and Valving................................................................................................................................. 5-3

5.3.1 Digested Solids Transfer Yard Piping............................................................................................ 5-3

5.3.2 Process Valving..................................................................................................................................... 5-4

5.4 Area Classification ............................................................................................................................................ 5-4

5.5 Heating, Ventilation, and Air Conditioning.............................................................................................. 5-4

5.6 Supervisory Control and Data Acquisition Improvements ................................................................. 5-6

5.6.1 Equipment and Tag Numbering Convention.............................................................................. 5-6

5.7 Communication Block Diagram................................................................................................................... 5-7

5.7.2 Preferred Instrumentation................................................................................................................ 5-8

5.8 Electrical Improvements ................................................................................................................................ 5-8

5.8.1 Motor Control Center for new Membrane Bioreactor Facility .............................................. 5-9

5.8.2 Motor Control Center for Attached Growth Facility, Filter Facility, and Waste Activated Sludge and Digested Sludge Storage Equipment..................................5-10

5.8.3 Outstanding Issues ............................................................................................................................5-11

5.9 Odor Control.....................................................................................................................................................5-12

5.9.1 Odor Source Descriptions ...............................................................................................................5-12

5.9.2 Odor Control System Sizing ...........................................................................................................5-14

5.9.3 Triggers Prompting Future Re-Evaluation of Odor Control ................................................5-15

5.10 Corrosion Control and Mitigation..............................................................................................................5-15

5.10.1 Atmospheric Conditions .............................................................................................................5-16

5.10.2 Immersion Exposure ....................................................................................................................5-18

5.10.3 Buried Exposure.............................................................................................................................5-19

5.10.4 Painting and Protective Coatings ............................................................................................5-24

6. References ...........................................................................................................................................................6-1 Tables
Table 1-1. Facility Improvements Summary .................................................................................................................... 1-1 Table 1-2. Historical Improvements Summary................................................................................................................ 1-2 Table 1-3. Summary of Tsunami Analysis Results at the Site .................................................................................... 1-7 Table 1-4. National Pollutant Discharge Elimination System R1-2023-0039 Effluent Limitations...........1-12 Table 1-5. North Coast Regional Water Quality Control Board Order Number R1-2017-0002 Effluent Limitations ....................................................................................................................................................1-13 RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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Table 1-6. City of Crescent City Wastewater Treatment Facility Disinfection Violations from 2020 to 2023................................................................................................................................................................1-14 Table 1-7. Anticipated Project Schedule .........................................................................................................................1-15 Table 1-8. Construction Sequencing Constraints .........................................................................................................1-16 Table 1-9. Possible Construction Activity Months........................................................................................................1-17 Table 2-1. Crescent City Wastewater Treatment Facility Dry Weather Season Influent Wastewater Characteristics ................................................................................................................................................................ 2-1 Table 2-2. Crescent City Wastewater Treatment Facility Wet Weather Season Influent Wastewater Characteristics ................................................................................................................................................................ 2-2 Table 2-3. 2022 to 2030 City of Crescent City Housing Element Update – 2010 to 2019 Population Growth......................................................................................................................................................... 2-4 Table 2-4. 2020 to 2025 Population Estimates for Crescent City............................................................................ 2-4 Table 2-5. Crescent City Wastewater Treatment Facility Upgrade Project Design Flows and Loads............ 2-4 Table 2-6. Wastewater Treatment Facility Peaking Factors ........................................................................................ 2-5 Table 2-7. Plant Performance Evaluation.......................................................................................................................... 2-5 Table 3-1. Membrane Bioreactor Train Capacities ......................................................................................................... 3-4 Table 3-2. Proposed Membrane Bioreactor Train 2 Additional Facility and Yard Piping Needs.................... 3-5 Table 3-3. Proposed Fine Screen Design Criteria ........................................................................................................... 3-5 Table 3-4. Proposed Bioreactor Design Criteria.............................................................................................................. 3-6 Table 3-5. Process Aeration System Design Criteria...................................................................................................... 3-7 Table 3-6. Mixed Liquor Pump Station Design Criteria................................................................................................. 3-8 Table 3-7. Transfer Pump Design Criteria ......................................................................................................................... 3-9 Table 3-8. Proposed Membrane Design Criteria............................................................................................................. 3-9 Table 3-9. Filtrate Pump Design Criteria .........................................................................................................................3-10 Table 3-10. Air Scour Blower Operating Requirements..............................................................................................3-10 Table 3-11. Attached Growth Facility Design Criteria.................................................................................................3-12 Table 3-12. Approximate Additional Piping...................................................................................................................3-13 Table 3-13. Pump Station Design Criteria.......................................................................................................................3-16 Table 3-14. Filter Influent Pump Station Piping ...........................................................................................................3-16 Table 3-15. Cloth Filter Design Criteria............................................................................................................................3-16 Table 3-16. Additional Piping Requirements for Filter Facility................................................................................3-17 Table 4-1. Waste Activated Sludge Storage Facility Design Conditions ................................................................. 4-6 Table 4-2. Digested Sludge Storage Design Criteria ..................................................................................................... 4-6 Table 4-3. Digested Sludge Pump Station Design Conditions................................................................................... 4-7 Table 4-4. Stored Solids Pump Station Design Conditions ......................................................................................... 4-7 Table 4-5. Waste Activated Sludge Storage Combination Mixing and Aeration Alternatives......................... 4-9 Table 4-6. Jet Aerator Design Criteria ..............................................................................................................................4-10 RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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Table 4-7. Digested Sludge Storage Mixing Alternatives .......................................................................................... 4-11 Table 4-8. Hydraulic Sludge Mixer Design Criteria ...................................................................................................... 4-11 Table 4-9. Gravity Thickener Facility Design Conditions ............................................................................................ 4-13 Table 4-10. Gravity Thickener Mechanism Design Criteria ....................................................................................... 4-13 Table 4-11. Anaerobic Digester Facility Design Conditions ...................................................................................... 4-15 Table 4-12. Cover and Gas Appurtenance Design Criteria ........................................................................................ 4-16 Table 5-1. Grit Removal Design Criteria ............................................................................................................................. 5-2 Table 5-2. Digested Sludge Transfer................................................................................................................................... 5-3 Table 5-3. General Valve Selection by Flow Stream ...................................................................................................... 5-4 Table 5-4. HVAC – New Facilities .......................................................................................................................................... 5-5 Table 5-5. HVAC Improvements – Existing Facilities ..................................................................................................... 5-6 Table 5-6. Motor Control Center 4002B .......................................................................................................................... 5-10 Table 5-7. Motor Control Centers 7201 and 7201A ................................................................................................... 5-11 Table 5-8. Liquids Processes Odor Sources .................................................................................................................... 5-12 Table 5-9. Solids Process Odor Sources ........................................................................................................................... 5-13 Table 5-10. Atmospheric Corrosion Classification ....................................................................................................... 5-16 Table 5-11. Corrosion Rates, for the First Year of Exposure for the Different Corrosivity Categories ........ 5-17 Table 5-12. Soil Resistivity Correlation with Corrosivity Levels ............................................................................... 5-19 Table 5-13. Corrosion Parameters ..................................................................................................................................... 5-20 Table 5-14. Effects Or Environmental Factors on Corrosion Of Steel In Soil ...................................................... 5-21 Table 5-15. Protective Coating Systems .......................................................................................................................... 5-24 Figures
Figure 1-1. City of Crescent City Location ......................................................................................................................... 1-4 Figure 1-2. Project Location ................................................................................................................................................... 1-5 Figure 1-3. Tsunami Design Zone Impacting the City of Crescent City Wastewater Treatment Facility.....1-6 Figure 1-4. Flood Insurance Rate Map for the Area Around the Wastewater Treatment Facility .................. 1-8 Figure 1-5. U.S. Army Corps of Engineers Technical Report H-78-26 Numerical Tsunami Modeling Results ............................................................................................................................................................ 1-9 Figure 1-6. City of Crescent City Wastewater Treatment Facility Site Plan .......................................................... 1-10 Figure 1-7. City of Crescent City Wastewater Treatment Facility Existing Process Flow Diagram ............... 1-10 Figure 2-1. Wastewater Treatment Facility Service Area .............................................................................................. 2-3 Figure 2-2. Hydraulic Profile for Proposed Process Flow ............................................................................................. 2-7 Figure 3-1. Liquid Stream Yard Piping Plan, Including Operational Flow Patterns ............................................ 3-1 Figure 3-2. Proposed Liquid Process Flow Diagram ...................................................................................................... 3-2 RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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Figure 3-3. Membrane Bioreactor Train 2 Arrangement.............................................................................................. 3-3 Figure 3-4. Proposed Membrane Bioreactor Train 2 Process Piping Routes ........................................................ 3-4 Figure 3-5. Proposed Membrane Bioreactor Blower Arrangement.......................................................................... 3-8 Figure 3-6. Filtrate Pumps for Membrane Bioreactor Train 2 Proposed Location............................................3-10 Figure 3-7. Attached Growth Facility Arrangement.....................................................................................................3-12 Figure 3-8. Cloth Filter Facility Layout .............................................................................................................................3-14 Figure 3-9. Filter Influent Pump Station Plan ................................................................................................................3-15 Figure 3-10. Filter Influent Pump Station Section........................................................................................................3-15 Figure 3-11. Section of Cloth Filter Facility ....................................................................................................................3-17 Figure 4-1. Proposed Solids Process Flow Diagram ...................................................................................................... 4-2 Figure 4-2. Waste Activated Sludge and Digested Sludge Storage Facilities ....................................................... 4-4 Figure 4-3. Digester Gas Foam Separator Location.....................................................................................................4-16 Figure 5-1. Proposed Digested Sludge Transfer Pipe Route ...................................................................................... 5-3 Figure 5-2. Electrical One-Line Diagram............................................................................................................................ 5-9 Figure 5-3. Motor Control Center 4002B Plan and Elevation .................................................................................... 5-9 Figure 5-4. Motor Control Centers 7201A Elevation...................................................................................................5-10 Appendices
Appendix A. National Pollutant Discharge Elimination System Permit R1-2023-0039 Appendix B. Time Schedule Order
Appendix C. Administrative Civil Liability Claim
Appendix D. Hydraulic Calculations
Appendix E. Equipment Cut Sheets
Appendix F. Heating, Ventilation, and Air Conditioning Replacement Markups Appendix G. Half Size One-Line Diagrams and Motor Control Center Plan and Elevations Appendix H. National Fire Protection Association 820 Area Classification RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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Acronyms and Abbreviations
μm/a micrometer(s) per year
Ω-cm ohm-centimeter(s)
°C degree(s) Celsius
°F degree(s) Fahrenheit
µg/L microgram(s) per liter
µm micrometer(s)
A ampere(s)
ACH air change(s) per hour
ACI American Concrete Institute
ACL Administrative Civil Liability Complaint
ADDW average day dry weather
ADWF average dry weather flow
AFC adjustable frequency controller
AGE attached growth effluent
ASCE American Society of Civil Engineers
ASTM ASTM International
AWWA American Water Works Association
AWWF average wet weather flow
BFP belt filter press
BOD biochemical oxygen demand
BODR basis of design report / 10% design
Btu British thermal unit(s)
Btu/hour British thermal unit(s) per hour
CB coarse bubble
CBC California Building Code
CEBC California Existing Building Code
CFU colony forming unit(s)
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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CIP clean in place
City City of Crescent City
CP cathodic protection
CRC corrosion-resistant coating
CSA County Service Area
DAC disadvantaged community
DFA Division of Financial Assistance
DIP ductile iron pipe
DO dissolved oxygen
DOF Department of Finance
DX direct exchange
EPA U.S. Environmental Protection Agency
EtherNetIP Ethernet/Internet Protocol
FEMA Federal Emergency Management Agency’s
FRP fiberglass-reinforced plastic
ft2/gal square foot (feet) per gallon
ft/s foot (feet) per second
ft2 square foot (feet)
ft3 cubic foot (feet)
ft
3/h cubic foot (feet) per hour
g/(m2·a) gram(s) per square meter per year
gpd gallon(s) per day
gpm gallon(s) per minute
GT gravity thickener
HDPE high-density polyethylene
HMI human-machine interface
hp horsepower
HVAC heating, ventilation, and air conditioning
I/O input/output
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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lb/day pound(s) per day
ISO International Standard Organization
lb O2/h pound(s) of oxygen per hour
LCP local control panel
MBR membrane bioreactor
MCC motor control center
MCP master control panel
MDFT minimum dry film thickness
MMADWW maximum month average day wet weather
MMDWF maximum month dry weather flow
MMWWF maximum month wet weather flow
MDWWF maximum day wet weather flow
mg/kg milligram(s) per kilogram
mg/L milligram(s) per liter
MGD million gallon(s) per day
ML mixed liquor
mL/L milliliter(s) per liter
mm/year millimeter(s) per year
MMP minimum monthly penalty
MPN Most Probable Number
mV millivolt(s)
N/A not applicable
NAVD88 North American Vertical Datum of 1988
NCUAQMD North Coast Unified Air Quality Management District NEC National Electrical Code
NEMA National Electrical Manufacturers Association
NFPA National Fire Protection Association
NGVD29 National Geodetic Vertical Datum of 1929
NOAA National Oceanic and Atmospheric Administration
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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NPDES National Pollutant Discharge Elimination System
NTU Nephelometric turbidity unit(s)
PHF peak hour flow
PDWW peak day wet weather
PLC programmable logic controller
ppm part(s) per million
PS pump station
psi pound(s) per square inch
PWDWF peak week dry weather flow
PWWWF peak week wet weather flow
RAS return activated sludge
RBC rotating biological contactor
rcorr corrosion rate
RDT rotary drum thickener
RWQCB North Coast Regional Water Quality Control Board
S/m siemen(s) per meter
sBOD soluble biochemical oxygen demand
SCADA supervisory control and data acquisition
scfm standard cubic foot (feet) per minute
SOTR standard oxygen transfer rate
SRF State Revolving Fund Program
SS stored solids
SST stainless steel
SU standard unit(s)
SRT solids retention time
SWRCB State Water Resources Control Board
TCDD 2,3,7,8-tetrachlorodibenzodioxin
TDH total dynamic head
TSO Time Schedule Order
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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TSS total suspended solid
TWAS thickened waste activated sludge
USACE U.S. Army Corp of Engineers
UV ultraviolet
V volt(s)
WAS waste activated sludge
WC water column
WEF Water Environment Federation
WSE water surface elevation
WWTF wastewater treatment facility
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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1. Introduction
Jacobs has prepared this Basis of Design Report /10% Design (BODR) on behalf of the City of Crescent City (City) for the preliminary design of the Wastewater Treatment Facility (WWTF) Upgrade Project.

1.1 Project Description
The City intends to design, construct, and operate the WWTF in compliance with the North Coast Regional Water Quality Control Board (RWQCB) Order Number R1-2017-0002, Waste Discharge Requirements.

Specifically, the project aims to achieve the following objectives:
 Provide membrane bioreactor (MBR) redundancy.
 Improve alternate secondary treatment process to achieve effluent limit compliance.  Add storage volume to the solids handling process to allow for operational flexibility.  Improve or replace failing equipment related to existing processes.

Table 1-1 summarizes the project improvements.

Table 1-1. Facility Improvements Summary
Facility Description of Work
Primary Clarifiers Replace failing mechanical equipment.

Resurface and recoat the basin interior walls and floors.

Grit Removal Replace grit cyclone(s), grit classifier, and grit piping.

MBRs Add redundant train.

RBCs Demolish mechanical equipment and retrofit basin with a modular attached growth process.

Secondary Clarifiers Demolish mechanical equipment and retrofit existing basins to contain the following facilities:
 Redundant MBR train
 Cloth filters to treat effluent from the attached growth process  Storage and pumping facilities for waste activated and digested sludge MBR Building Add equipment to support new MBR facility.

GT Replace entire mechanism and supporting mechanical equipment, recoat interior concrete, and add cover to facility.

Anaerobic Digesters Replace floating covers with fixed covers and install associated gas collection and safety equipment and replace boiler.

HVAC Install new HVAC equipment in the pump gallery (6 ACH).

Replace or upgrade HVAC equipment in:
 Administration building (complete replacement)
 MBR building chemical room (replace corroded ductwork and fan with 316 SST)
 Digester building (replace fan only, 12 ACH)
 Dewatering building (replace fan and ductwork, 6 ACH) SCADA and Electrical Complete general improvements to support upgraded facilities.

RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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ACH = air change(s) per hour
GT = gravity thickener
HVAC = heating, ventilation, and air conditioning
RBC = rotating biological contactor
SCADA = supervisory control and data acquisition
SST = stainless steel

1.1.1 Project Funding
The proposed upgrade project will be fully grant funded from the California State Revolving Fund Program (SRF) by applying principal forgiveness, as administered through the State Water Resources Control Board’s (SWRCB’s) Division of Financial Assistance (DFA). The WWTF’s service area is considered a disadvantaged community (DAC). The SWRCB DFA places a high priority on funding improvements designed to alleviate financial burdens for DACs while improving the overall water quality in the State of California.

1.1.2 Previous Reports
This BODR develops the preliminary design of the selected alternative from the Project Report (Jacobs 2025) in preparation for final design and construction, pending project funding acquisition.

The Project Report (Jacobs 2025) considered alternatives to install a redundant MBR train and replace the aging RBC facility. The limited capacity and failing infrastructure of these two facilities contribute to the WWTF’s reoccurring effluent violations for fecal coliform and enterococci. The selected alternative was to convert the secondary clarifier basins to a redundant MBR train, cloth filtration, and solids storage. The RBC facility will be converted to an attached growth biological treatment facility. No new structures will be constructed with this upgrade project; only existing structures will be modified to contain the new facilities.

The Project Report (Jacobs 2025) also referenced previous assessment work Jacobs conducted at the WWTF, including a site visit conducted on August 17, 2022, and a condition assessment conducted in May 2023. These reports detailed the condition of various plant appurtenances, including the aging and failing infrastructure related to the wooden facilities at the primary clarifiers, the failing floating covers on the anaerobic digesters, the corroded GT, and the failing HVAC systems at numerous locations around the plant. This BODR defines these upgrade/replacement recommendations, along with the major liquid process overhaul selected in the alternatives analysis.

1.1.3 Project History
The WWTF was constructed in the early 1950s, and there were three major upgrade projects in 1973, 1977, and from 2008 to 2011. Table 1-2 summarizes the improvements for each project and the approximate facility plan expansion.

Table 1-2. Historical Improvements Summary
Project
Construction Year Improvements Summary
Approximate
WWTF Footprint
1950 Original Construction:
 Influent pump house and wet well
 Clarigester
 Waste gas burner
4,000 ft2
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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Project
Construction Year Improvements Summary
Approximate
WWTF Footprint
1973 Constructed:
 Control building
 Two primary clarifiers with pre-aeration basins
 Chlorine contact basin
 GT
 Associated sludge pumping facilities
Converted:
 Existing clarigester to a digester
Improved:
 Influent pump house
 Outfall
35,000 ft2
1977 Constructed:
 Three RBC trains
 Two secondary clarifier trains
 New chlorine contact basin
 Primary digester
Converted:
 Chlorine contact basin to seawater storage basin
 Existing digester to secondary digester
Replaced/Relocated:
 Waste gas burner
Improved:
 outfall
60,000 ft2
2005 Constructed:
 24-inch outfall
60,000 ft2
2008 to 2011 Constructed:
 One MBR train
 MBR equipment building
 Dewatering belt filter press facility
 Odor control facility
Improved/Expanded:
 Control building
 Headworks and influent pump station
Relocated:
 Secondary containment chemical facility
66,000 ft2
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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Because the age of the existing equipment predates the 2008 to 2011 project, the WWTF requires extensive rehabilitation to maintain continuous operation. Additionally, effluent limits imposed by the National Pollutant Discharge Elimination System (NPDES) Order Number R1-2023-0039 adopted on December 12, 2023, require a secondary treatment facilities upgrade because the existing treatment process does not reliably meet effluent criteria. This BODR defines the recommended improvements to address these concerns and develops the preliminary design of the liquid stream improvements alternative that was selected for the secondary treatment process upgrade in the 2025 Project Report (Jacobs 2025). These improvements have been selected to be permittable, considering current building code provisions for tsunami design.

1.2 Project Location
The City is on the Northern California coast, 15 miles south of the Oregon border in Del Norte County, as pictured on Figure 1-1. The project’s location, as shown on Figure 1-2, directly on the coast is susceptible to tsunami events following large earthquake events occurring in the Pacific Ocean. In addition, the project is underlain by loose, saturated alluvial sand and uncontrolled artificial fill materials. The loose sand may liquefy in the event of a large earthquake. One of the consequences of liquefaction is potential settlement between 3 to 6 inches (GeoVision 2004). The uncontrolled fill materials are subject to excessive total and differential settlement under new foundation loads. Because of these site conditions, existing foundations will be used to support proposed upgrade improvements to avoid a need for extensive subsurface preparation, deep foundation support, or tsunami protections.

Source: Google 2025
Figure 1-1. City of Crescent City Location
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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Microsoft product screenshot(s) reprinted with permission from Microsoft Corporation.

Figure 1-2. Project Location

1.2.1 Relevant Hydrological, Geologic, and Topographic Features The service area is on the Smith River Plain bordered by the Pacific Ocean to the west and the base of the Coast Mountain Range to the east. The topography within 2 miles of the City is essentially flat and slopes gently south toward the harbor and east toward Elk Creek. The City has a maximum elevation change of 66 feet and an average elevation above sea level of 19 feet. The area within 2 miles of the City is covered by herbaceous vegetation (35%), water (34%), and artificial surfaces (24%).

The local geology beneath the WWTF was observed in soil borings performed by GeoVision in 2004.

The subsurface materials consisted of artificial fill material, alluvium or terrace deposits, and rock of late Pleistocene Battery Formation (Delattre and Rosinski 2012). The artificial fill contained wood debris, concrete rubble, low density material, and organics that indicated the fill was not engineered or placed in controlled, compacted lifts. The alluvium consisted of loose to medium dense fine sand. Terrace deposits consisted of silt, organics, and clay. The Battery Formation consisted of very soft to soft siltstone and sandstone.

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The potential for settlement should be evaluated where new loads are placed on existing shallow footings.

Settlement may be estimated by design charts for footings on sand (Peck et al. 1974) based on blow counts and the load pressure. If existing foundations are supported on deep foundations that penetrate the Battery Formation, the estimated settlement would be negligible unless the stress within the pile material exceeds the strength of the pile.

Groundwater was encountered in field exploration borings within a foot of the ground surface.

Groundwater should be considered to be at the ground surface for design purposes.

1.2.2 Tsunami Code Application
As shown on Figure 1-3, the WWTF lies within a Tsunami Design Zone, where the design of new structures may be required to consider tsunami effects. Structures are assigned Tsunami Risk Categories determined in accordance with American Society of Civil Engineers (ASCE) 7-22, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, as referenced from the 2025 California Building Code (CBC). Typically, the Tsunami Risk Category is the same as the Risk Category assigned by the CBC for seismic and wind loads. Risk Category IV (the highest category, including other critical structures, such as hospitals) is assigned to public wastewater treatment plants. For design for tsunamis, however, ASCE 7-22 and Section 1604.5 of the CBC allow the Tsunami Risk Category to be dropped to Category III by federal, state, local, or tribal governments for treatment plants. Therefore, Tsunami Risk Category III will be considered for this site.

Figure 1-3. Tsunami Design Zone Impacting the City of Crescent City Wastewater Treatment Facility Source: ASCE n.d.

Design for the impacts of tsunamis is mandated under the CBC for all Tsunami Risk Category IV structures.

It is not required for Tsunami Risk Category III structures where the inundation depth at the structure does not exceed 3 feet above existing grade level at the center of the structure in question.

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Preliminary energy grade line analyses were conducted for the site using ASCE’s Tsunami Hazard Tool (asce7tsunami.online) on the six transept lines (“A” through “C”) that are shown on Figure 1-3 that cover the range of flow directions required to be considered in determining the inundation depth. Table 1-3 summarizes the results of the energy grade line analyses. Ground level at the plant is higher than the surrounding areas. However, the site is still inundated by the Maximum Considered Tsunami with a 2,475-year return period, which the code requires be considered. The 33.90-foot depth of inundation over the typical finish grade elevation at the site as calculated well exceeds the 3-foot limit to avoid tsunami design for structures in Tsunami Risk Category III.

Table 1-3. Summary of Tsunami Analysis Results at the Site Transept
Inundation
Depth
Ground Elevation at
Point Considered
Tsunami Flow
Velocity
A (perpendicular to shoreline) 33.82 feet Elevation 19.70 (NAVD88)

41.13 ft/s
B (22.5 degrees counterclockwise from
transept A)

28.55 feet Elevation 19.70
(NAVD88)

36.81 ft/s
C (22.5 degrees clockwise from transept A) 33.90 feet Elevation 19.70 (NAVD88)

39.08 ft/s
ft/s = foot (feet) per second
NAVD88 = North American Vertical Datum of 1988
With an inundation depth greater than 3 feet, ASCE 7-22 requires debris impact loads to be considered.

For inundation depths greater than 16 feet, “extraordinary debris impacts” on structures involving the largest ships and barges with ballasted drafts less than the inundation depth that can be dispersed from nearby ports, harbors, or shipping container yards must be considered (ASCE 7-22, Section 6.11.7). Such impacts can occur at this site for tsunamis that happen more frequently.

For existing structures, the 2025 California Existing Building Code (CEBC) does not explicitly require consideration of tsunami loads. However, repairs, alterations, and additions to existing structures that constitute substantial improvements are typically not allowed in flood hazard areas without following the provisions for new building designs. Floods with a 1% probability of exceedance in any given year (100-year return period) are used to determine the flood hazard area.

Federal Emergency Management Agency’s (FEMA’s) Flood Insurance Rate Map for the area on Figure 1-4 shows 100-year water levels offshore associated with “VE” zones related to storm waves. In the area of those zones, the FEMA Flood Insurance Study for Del Norte County, California, and Incorporated Areas (2017) indicates the following:
“The coastal analysis indicated the eroded beach profile was either not overtopped by the 1% total water level (TWL), or the overtopping splash zone did not extend beyond the landward limit of the primary frontal dune (PFD) for most transects. In that case, the mapping was limited to a VE zone extending from map datum (0 ft NAVD88) to the landward limit of the PFD.”
Therefore, the “VE” zones do not indicate 100-year water levels overtopping the WWTF site that would require application of design for flooding under the CEBC.

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Figure 1-4. Flood Insurance Rate Map for the Area Around the Wastewater Treatment Facility Source: FEMA 2017
The Flood Insurance Study (FEMA 2017) products do not include non-regulatory information about tsunami runup elevations. The U.S. Army Corps of Engineers (USACE) published Technical Report H-78-26 (USACE 1978), which provided elevations for the 100- and 500-year return period tsunamis along the west coast of the United States. Figure 1-5 shows the results of the numerical modeling from that study, which do not include adjustments for sea level rise and seismic ground subsidence. The 100-year runup elevation was found to be 13.9 feet (National Geodetic Vertical Datum of 1929 [NGVD29]), while the 500-year runup elevation was determined to be 24.9 feet (NGVD29). By comparison, the technical report (USACE 1978) results using a probabilistic evaluation of historical data were 14.5 and 25.5 feet (NGVD29) for the 100- and 500-year tsunami events, respectively. Converting to the NAVD88 datum with a 2.05-foot future sea level rise over 50 years in accordance with the National Oceanic and Atmospheric Administration’s (NOAA’s) Sea Level Calculator, the 100-year tsunami event would have a runup elevation of 16.94 feet.

Runup elevations are approximately equal to the tsunami flood elevation at the shoreline (with a difference of 1.3 feet in the energy grade line analyses for the 2,475-year tsunami). Given that neither the storm wave nor tsunami historical data indicate the WWTF site is inundated at a 1% probability of exceedance, the site is not considered to fall within a flood hazard area. Substantial improvements can be made to existing structures without meeting the requirements of ASCE 7-22 for flood design.

Given the high costs inherent in protecting new structures from over 30 feet of water and ship impacts, the project is designed to modify and use the existing structures at the site to house the new treatment processes. With the site sitting above the 100-year flood elevation, no modifications to the existing foundations are required using that approach to protect against erosion occurring during tsunami runup and drawdown conditions.

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Figure 1-5. U.S. Army Corps of Engineers Technical Report H-78-26 Numerical Tsunami Modeling Results Source: USACE 1978
For new Risk Category IV buildings in a Tsunami Design Zone, nonstructural components needed for the facility to function would have to be either protected from tsunami inundation effects or positioned in the structure above the inundation elevation of the Maximum Considered Tsunami. That requirement is not modified by placing the structures in Tsunami Risk Category III. Design of the project under the CEBC using existing structures also precludes the need to provide those protections for new equipment.

1.3 Existing Treatment Facilities
The WWTF treatment process consists of physical, mechanical, biological, and chemical methods that combine to treat sewage from the incorporated Crescent City area. The influent raw waste consists of primarily domestic sewage with some commercial contributions. The WWTF is permitted to treat and discharge an annual average daily flow of 1.86 million gallons per day (MGD) and a peak day flow of

6.12 MGD, and it primarily discharges tertiary treated effluent through an ocean outfall. Figure 1-6 shows a plan view of the existing treatment facilities. Figure 1-7 shows the existing process flow diagram.

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Microsoft product screenshot(s) reprinted with permission from Microsoft Corporation.

Figure 1-6. City of Crescent City Wastewater Treatment Facility Site Plan Figure 1-7. City of Crescent City Wastewater Treatment Facility Existing Process Flow Diagram RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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The WWTF liquid treatment stream consists of preliminary, primary, secondary, and disinfection treatment.

The preliminary process consists of screening and aerated grit removal, which are ultimately disposed of in a landfill. The primary treatment process removes particulate settleable solids by gravity and allows the soluble biodegradable liquid stream to flow through to the downstream processes. The particulate settled solids are sent to the solids stream treatment process for further treatment. The secondary treatment process consists of two separate treatment streams, with one being an RBC and the other stream being an MBR process. The RBC effluent flow is sent to a secondary clarifier for gravity settling of solids, and the effluent is combined with the MBR permeate for downstream disinfection. One goal of both secondary treatment processes is to convert the soluble readily biodegradable carbon or soluble biochemical oxygen demand (sBOD) to biological cells, which are ultimately removed in the solids treatment stream. The other goal in treatment is removal of nitrogen in the MBR process through anoxic and aerobic biological reactions. Disinfection of the combined secondary effluents are accomplished by dosing sodium hypochlorite to achieve a chlorine residual near 3 milligrams per liter (mg/L). Dechlorination is then completed by adding sodium bisulfite after post chlorine contact chamber. The final effluent is then discharged to the ocean on the south side of Battery Point Lighthouse.

In the solid process stream, primary sludge is pumped into the GT. GT sludge is thickened and fed to the anaerobic digester. Waste activated sludge (WAS) from the MBRs is pumped to the rotary drum thickener (RDT). The thickened waste activated sludge (TWAS) is then fed directly to the anaerobic digester. Digested sludge is dewatered using a belt filter press (BFP), and BFP cake is then transported to the landfill.

The WWTF’s primary treatment system consists of two aerated grit removal tanks followed by two rectangular primary clarifiers. Primary sludge is pumped to the GT. Floatable scum and grease are mechanically skimmed and pumped to the GT.

Secondary treatment is provided by operating the RBC and MBR in parallel. The RBC system consists of three trains of four-stage RBCs with a combined surface area of 1.2 million ft2. Flow from the RBCs reach three rectangular secondary clarifiers, where the biological solids settle. The solids are drawn to hoppers at the inlet end of the tanks, where the solids are removed and pumped to the RDT, with an option to be pumped to the GT.

The existing RBC facility has been experiencing recurring mechanical issues. As of March 2025, 4 of 12 RBC units were offline for mechanical issues, and the remaining RBC units are not up to the expected treatment performance, resulting in high suspended solids in the clarified effluent.

The MBR treatment system uses a similar population of bacteria and identical biochemical pathways to those found in other aerated biological processes to convert soluble and particulate biochemical oxygen demand (BOD). Bacteria are concentrated and supplied with oxygen in the aeration basin. The bacteria consume BOD and convert it to carbon dioxide and water as they metabolize and reproduce.

1.3.1 National Pollutant Discharge Elimination System Permit Information The WWTF operates under the NPDES Order Number R1-2023-0039. This order was adopted by the RWQCB on December 12, 2023, became effective on February 1, 2024, and expires on January 31, 2029.

Appendix A includes the permit. Table 1-4 summarizes the effluent limitations.

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Table 1-4. National Pollutant Discharge Elimination System R1-2023-0039 Effluent Limitations Parameter Units
Average
Monthly
Average
Weekly
Maximum
Daily
Instantaneous
Minimum
Instantaneous
Maximum
6-Month
Median
BOD5 at
20°C
mg/L 30 45 N/A N/A N/A N/A
TSS mg/L 30 45 N/A N/A N/A N/A
pH SU N/A N/A N/A 6.0 9.0 N/A
Oil and
Grease
mg/L 25 40 N/A N/A 75 N/A
Ammonia
Nitrogen,
Total (as N)
mg/L N/A N/A 72 N/A 180 18
Settleable
Solids
mL/L 1.0 1.5 N/A N/A 3.0 N/A
Turbidity NTU 75 100 N/A N/A 225 N/A
Copper,
Total
Recoverable
µg/L N/A N/A 300 N/A 840 32
Silver, Total
Recoverable
µg/L N/A N/A 79 N/A 200 16
Endosulfan µg/L N/A N/A 0.54 N/A 0.81 0.27
Endrin µg/L N/A N/A 0.12 N/A 0.18 0.060
Total
Residual
Chlorine
µg/L N/A N/A 240 N/A 1,800 60
DDT µg/L 0.0051 N/A N/A N/A N/A N/A
Heptachlor µg/L 0.0015 N/A N/A N/A N/A N/A
Dieldrin µg/L 0.0012 N/A N/A N/A N/A N/A
°C = degree(s) Celsius
µg/L = microgram(s) per liter
BOD5 = biological oxygen demand 5-day
DDT = dichlorodiphenyltrichloroethane
mL/L = milliliter(s) per liter
N/A = not applicable
NTU = Nephelometric turbidity unit(s)
SU = standard unit(s)
TSS = total suspended solids

1.3.1.1 Additional Requirements
 Facility Permitted Flow
- Average dry weather flow (ADWF) through the WWTF must not exceed 1.86 MGD, measured daily and averaged over a calendar month.

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- Average wet weather flow through the WWTF must not exceed 6.12 MGD, measured daily and averaged over a calendar month.
 Disinfection Requirements
- Enterococci: The 6-week rolling geometric mean must not exceed 30 colony forming units (CFU) per 100 milliliters, and no sample must exceed a CFU of 110 per 100 milliliters. - Total Coliform Organisms: The median value of total coliform bacteria must not exceed a Most Probable Number (MPN) of 70 per 100 milliliters in a calendar month, and not more than 10% of the samples collected in a calendar month can exceed an MPN of 230 per 100 milliliters. - Fecal Coliform: The 30-day geometric mean of fecal coliform density must not exceed 200 per 100 milliliters.

1.3.1.2 Previous Permit Cycle
The permit cycle preceding NPDES Order Number R1-2023-0039 was RWQCB Order Number R1-2017-0002. This permit was adopted on February 2, 2017, was effective on April 1, 2017, and expired on March 31, 2022. Table 1-5 summarizes the effluent limitations from this previous permit cycle.

Table 1-5. North Coast Regional Water Quality Control Board Order Number R1-2017-0002 Effluent Limitations
Parameter Units
Average
Monthly
Average
Weekly
Maximum
Daily
Instantaneous
Minimum
Instantaneous
Maximum
6-
Month
Median
BOD5 at
20°C
mg/L 30 45 N/A N/A N/A N/A
lb/day 465 700 N/A N/A N/A N/A
TSS mg/L 30 45 N/A N/A N/A N/A
lb/day 465 700 N/A N/A N/A N/A
pH SU N/A N/A N/A 6.0 9.0 N/A
Oil and
Grease
mg/L 25 40 N/A N/A 75 N/A
Ammonia
Nitrogen,
Total (as N)
mg/L N/A N/A 72 N/A 180 18
Settleable
Solids
mL/L 1.0 1.5 N/A N/A 3.0 N/A
Turbidity NTU 75 100 N/A N/A 225 N/A
Copper,
Total
Recoverable
µg/L N/A N/A 300 N/A 840 32
Nickel, Total
Recoverable
µg/L N/A N/A 600 N/A 1,500 150
Total
Residual
Chlorine
µg/L N/A N/A 240 N/A 1,800 60
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Parameter Units
Average
Monthly
Average
Weekly
Maximum
Daily
Instantaneous
Minimum
Instantaneous
Maximum
6-
Month
Median
Dieldrin µg/L 0.0012 N/A N/A N/A N/A N/A
TCDD
Equivalents
µg/L 1.2 x
10(-7)

N/A N/A N/A N/A N/A
lb/day = pound(s) per day
TCDD = 2,3,7,8-tetrachlorodibenzodioxin

1.3.1.3 Disinfection Requirements
 Fecal Coliform: The median value of fecal coliform bacteria must not exceed a MPN of 14 per 100 milliliters in a calendar month, no more than 10% of samples collected in a calendar month can exceed an MPN of 43 per 100 milliliters, and no single sample can exceed an MPN of 400 per 100 milliliters.

1.3.1.4 Historical Discharge Violations
Under RWQCB Order Number R1-2017-0002, the WWTF experienced disinfection-related permit limit exceedances for total residual chlorine and fecal coliform. Under NPDES Order Number R1-2023-0039, the WWTF experienced permit limit exceedances for total residual chlorine, fecal coliform, total coliform, and enterococcus. Table 1-6 lists the number of Crescent City WWTF’s reported effluent quality disinfection-related violations in accordance with California Integrated Water Quality System Facility Identification 216106 for calendar years 2020 to 2024.

Table 1-6. City of Crescent City Wastewater Treatment Facility Disinfection Violations from 2020 to 2023 Year
Total Chlorine
Residual
Fecal
Coliform
Total
Coliform Enterococcus
Total
per Year
2020 8 3 N/A N/A 11
2021 2 2 N/A N/A 4
2022 1 2 N/A N/A 3
2023 1 2 N/A N/A 3
2024 1 2 18 21 42
Total per Constituent 13 11 18 21 N/A
The data show the WWTF had difficulty meeting the existing disinfection limits for total chlorine residual and fecal coliform. The WWTF experienced significantly more frequent violations related to the new, more stringent total coliform and enterococcus effluent limits.

The City WWTF received a Time Schedule Order (TSO) (R1-2025-0015) from the California Regional Water Quality Control Board, North Coast Region, adopted June 6, 2025, which provided time schedules to comply with the effluent limitations for enterococci and total coliform bacteria, established under NPDES Order Number R1-2023-0039. Appendix B provides the TSO.

The liquid stream upgrades proposed in this BODR were selected in the Project Report (Jacobs 2025) as improvements that would allow the WWTF to achieve discharge compliance with NPDES Order Number R1-2023-0039 under design influent flow and loading conditions.

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1.3.1.5 Administrative Civil Liability Complaint
The City received an Administrative Civil Liability Complaint (ACL) from the RWQCB for violation of effluent limitations contained in RWQCB Order Number R1-2017-0002 and NPDES Order Number R1-2023-0039.

The violations include the previously cited violations and additional violations totaling 76 chronic violations.

The additional violations not shown in Table 1-6 include one settleable solids violation and three ammonia, total as N, violations. Appendix C includes the ACL claim. The RWQCB is required to assess minimum monthly penalties (MMP) of $3,000 for each serious violation, not counting the first three violations. The City WWTF was assessed an MMP of $228,000 for the effluent limitation exceedances.

1.4 Project Schedule Update
Table 1-7 includes an update to the project schedule presented in the Project Report (Jacobs 2025).

This table lists the milestones required to apply for principal forgiveness with the SRF as administered through the SWRCB’s DFA for project implementation through construction. The proposed schedule is subject to the following conditions and requirements:

1. Grant application review and approval by DFA

2. Grant agreement preparation and approval by DFA

3. Environmental review from participating agencies

4. Other constraints and durations that are out of the control of the City or Jacobs The schedule assumes the City will place a public Request for Proposals for the final design of the upgrade project once funding has been secured. It is recommended that the selected engineering consultant complete the final design based on this BODR and provide bidding assistance and engineering services during construction. The final design period is estimated at 2 years, and the construction period is estimated at 5 years. The project is expected to be completed by late 2035.

Table 1-7. Anticipated Project Schedule
Project Milestones Approximate Schedule/Timeline
SWRCB DFA Funding Approval November 30, 2023
Clean Water SRF Application
General Information Package October 2023 to March 2026
Technical Package: October 2023 to March 2026
Project Report (Jacobs 2025) October 2023 to July 2025
BODR June 2025 to December 2025
Class 4 Cost Estimate December 2025 to January 2026
Environmental Package October 2025 to March 2026
Financial Security Package October 2025 to March 2026
DFA Funding Application Review Period and
Funding Agreement Development
March 2026 to March 2028
Request for Proposals for Final Design March 2028 to May 2028 Final Design June 2028 to June 2030
Construction Bidding and Award July 2030 to September 2035 Construction Duration October 2030 to October 2035
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1.4.1 Construction Sequencing
Construction sequencing is essential for managing projects effectively and ensuring continued WWTF operation during construction activities, considering influent flow patterns and fluctuations. Table 1-8 lists the construction sequencing constraints. The flow periods associated with the peak flows stated in Table1-8 are listed in Table 1-9.

Table 1-8. Construction Sequencing Constraints
Facility Description of Work Sequencing Constraints
Primary Clarifiers Replace failing mechanical
equipment.

Resurface and recoat the basin
interior walls and floors.

Maintain one primary clarifier online at all
times.

Complete during dry season.[a]
Grit Removal Replace grit cyclone(s), grit
classifier, and grit piping.

N/A.

MBRs Add redundant train. N/A.

RBCs Demolish mechanical equipment
and retrofit basin with a modular
attached growth process.

RBC demolition and attached growth facility
construction to occur during one dry
season[a] when influent flows are less than

1.8 MGD. Construction coincide with cloth
filter facility construction.

OR
Demolition and construction activities
commence after MBR Train 2 is brought
online and during one dry season[a] when
influent flows are less than 3.6 MGD.

Secondary Clarifiers Demolish mechanical equipment
and retrofit existing basins to
contain the following facilities:
 Redundant MBR train
 Cloth filters to treat effluent
from the attached growth
process
 Storage and pumping
facilities for waste activated
and digested sludge
Must maintain minimum of two secondary
clarifier trains online outside of allowed
shutdown periods described as follows.

Secondary clarifier demolition and new
facility construction to occur during one dry
season[a] when influent flows are less than

1.8 MGD. Cloth filter facility construction
coincide with attached growth facility
construction.

OR
Demolition and construction activities
commence after MBR Train 2 is brought
online and during one dry season when
influent flows are less than 3.6 MGD.

MBR Building Add equipment to support new
MBR facility.

N/A.

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Facility Description of Work Sequencing Constraints
GT Replace entire mechanism and
supporting mechanical
equipment, recoat interior
concrete, and add cover to
facility.

N/A.

Anaerobic Digesters Replace floating covers with
fixed covers and install
associated gas collection and
safety equipment. Replace boiler
One anaerobic digester will remain
operational at all times.

Construction of digester roofs to occur after
digested sludge storage basin is complete.

HVAC Install new HVAC equipment in
the pump gallery (6 ACH).

Replace or upgrade HVAC
equipment in:
 Administration building
(complete replacement)
 MBR building chemical room
(replace corroded ductwork
and fan with 316 SST)
 Digester building (replace fan
only, 12 ACH)
 Dewatering building (replace
fan and ductwork, 6 ACH)
N/A.

SCADA and
Electrical
Complete general improvements
to support upgraded facilities.

N/A.
[a] Refer to Table 1-9 for “dry season” definition.

Table 1-9. Possible Construction Activity Months
Construction Constraint Activity Flow Condition
Possible Construction
Months
Primary Clarifier Rehabilitation Dry season operation May to October RBC Demolition
Secondary Clarifier Demolition
Maximum 3.6 MGD with two MBR
trains online
OR
Maximum 1.8 MGD with one MBR
train online
April to November
July to September
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1.4.2 Class 4: Conceptual Estimate
A Class 4 Estimate of Construction Cost will be prepared in accordance with American Association of Cost Engineers, International guidelines and based on the 15% concept design. A Class 4 estimate has a -20% to +30% accuracy range and is used to provide preliminary budgeting and economic feasibility. The Class 4 estimate is compiled using semi-detailed, parametric, and analogous estimating supported by historical cost data and project-specific budgetary cost data, if obtained. Jacobs has a dedicated cost estimating team that will review the information presented in this report and use it as the basis to produce a Class 4 estimate. The estimate of construction cost will be provided under a separate cover to the client within 4 weeks of the final report completion.

1.4.3 Environmental Considerations
The following information is provided to inform the environmental review associated with this project.

1.4.3.1 Ground-Disturbing Construction Activities
The project will be designed to not construct any new foundations. Therefore, no excessive excavation is expected.

Minor excavation will be required to install buried yard piping, conduit runs, and other utilities. However, because this piping is being installed in an already congested plant site, it is assumed the yard piping excavations will be fairly shallow (less than 5 feet deep, with exception for crossings). Excavation will be performed using typical construction backhoe equipment. Where excavations are less than 5 feet deep, shoring is not required.

There may be minor work outside the fence line of the WWTF to support the construction activities, such as concrete truck and crane access or parking. There is limited room within the plant property for equipment access, so it is anticipated that the construction laydown area, for parking of large equipment, will need to be outside the fence line to conduct construction activities.

1.4.3.2 Visual Impacts
The project includes the demolition of the above-grade RBC equipment. This demolition will improve the sight lines through the plant at this location.

The project includes the construction of a redundant MBR system, which will include an overhead crane.

This system and crane equipment will be adjacent to and likely resemble the size and height of the existing equipment. No major visual impacts are expected from this facility because the facility is adjacent to a taller existing building.

The project includes modifications to the existing anaerobic digesters and GT facilities. The work will change the above-grade equipment, and therefore visual appearance, but will not majorly impact the existing view. One digester roof will be raised by 2 feet, but the overall height of this facility will be reduced because the current facility includes guide rails for the floating cover that extend multiple feet into the air. The GT will be covered, but the intent is to provide at-grade covers, so this improvement will also not impact the existing view.

All other improvements will be contained within existing buildings or structures.

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1.4.3.3 Construction Duration and Sequencing
The assumed construction schedule includes a 5-year duration, with typical Monday through Friday work days and 7:30 a.m. to 4:30 p.m. work hours, including all required breaks. No overtime or night work is expected for this project.

The WWTF must remain operational during the entire construction project. Therefore, the contractor must present a construction schedule that allows for proper sequencing of construction activities to allow the WWTF to remain functional and produce effluent that at least meets the previous effluent quality conditions. Additionally, the contraction must provide a schedule that allows for adequate treatment capacity to be online during the wet season because this is when the WWTF experiences disinfection-related violations. The wet season will be defined in the construction documents.

1.4.3.4 Construction Equipment Assumptions
This project does not anticipate any deep excavations or pile driving activities. The assumed construction equipment required to complete the work includes the following:
 Overhead cranes
 Concrete trucks and consolidation equipment
 Mini excavator/backhoe
 Asphalt-laying equipment
 Other typical handheld construction equipment to complete the work

1.4.3.5 Stormwater Pollution and Prevention Plan
The stormwater pollution and prevention plan and maintenance of onsite best management practices in accordance with the plan will be the responsibility of the contractor.

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2. Flows and Loading Design Criteria
This section describes the flows and loading design criteria.

2.1 Historical Flows and Loads
The analysis of historical flow and load data forms the basis of developing wastewater flow projections.

The following assessment of current and historic flow conditions for the WWTF is based on operating data from January 2021 through September 2025.

2.2 Wastewater Flows
Because wastewater flows vary seasonally and in response to precipitation, several different flow conditions are important in sizing and evaluating wastewater treatment plants.

The flow rate and related parameters discussed in this section are defined as follows:
 Average Dry Weather Flow (ADWF). The average of daily flows over the 6-month dry weather season (May 1 through October 31).
 Average Wet Weather Flow (AWWF). The average flow at the plant during the wet weather season (November 1 through April 30) during a year with average rainfall.  Maximum Month Dry Weather Flow (MMDWF). The monthly average flow corresponding to the wettest dry weather month.
 Maximum Month Wet Weather Flow (MMWWF). The anticipated monthly average flow corresponding to the wettest wet weather month.
 Peak Hour Flow (PHF). The peak flow sustained for 1-hour during a consecutive 24-hours

2.2.1 Wastewater Treatment Facility Flow Analysis
Table 2-1 and Table 2-2 summarize the dry weather and wet weather flows and pollutant characteristics data for the period from January 2021 through September 2025, respectively. Table 2-1 and Table 2-2 presents influent flow, in pound per day, in MGD, BOD, and TSS loading.

The average and maximum month TSS influent load is trending upward during the dry and wet weather conditions, but the BOD influent loading is relatively steady. The cause of this increase is currently unknown, and further evaluation is required.

Table 2-1. Crescent City Wastewater Treatment Facility Dry Weather Season Influent Wastewater Characteristics
Year
Flow, MGD TSS, lb/day BOD, lb/day Ammonia, lb/day

ADWF MMDWF ADWF MMDWF ADWF MMDWF ADWF MMDWF
2021 1.03 1.27 2,777 3,182 2,893 3,191 271 329
2022 1.14 1.58 2,320 2,578 2,747 3,292 277 313
2023 0.95 2.19 2,125 2,999 2,377 2,849 277 347
2024 1.22 1.54 1,941 2,337 2,382 2,698 288 421
2025 0.96 1.95 3,537 4,258 2,922 3,569 256 292
Summary 1.02 1.71 2,540 3,071 2,664 3,120 274 341
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
2-2
Table 2-2. Crescent City Wastewater Treatment Facility Wet Weather Season Influent Wastewater Characteristics
Year
Flow, MGD TSS, lb/day BOD, lb/day Ammonia, lb/day

AWWF MMWWF AWWF MMWWF AWWF MMWWF AWWF MMWWF
2021 1.43 2.70 2,776 3,366 2,838 3,191 243 294
2022 1.23 1.97 2,246 2,578 2,729 3,292 278 303
2023 1.50 2.95 2,299 3,215 2,506 3,025 271 311
2024 2.27 3.79 2,527 3,358 2,815 3,576 230 269
2025 2.23 3.05 3,556 4,175 3,117 3,379 250 283
Summary 1.51 3.79 2,456 3,366 2,705 3,576 254 311

2.3 Service Area
The WWTF’s service area includes the City limits and the surrounding Del Norte County Service Area (CSA).

The CSA consists of the following two subareas:
 CSA District #1: Bertsch Ocean View Area to the east
 CSA District #2: Northeast area (North of the City)
Figure 2-1 shows a map of the service area.

The service area location and growth assumptions are discussed in the next section.

2.3.1 Service Area Growth Projections
Since 2010, the City’s population has been in decline, as presented in Table 2-3. The population growth of Del Norte County is also included in this analysis because it includes the population of Crecent City.

The 2022-2030 Housing Element Update (City 2023) states that the State of California’s Department of Finance (DOF) provides population projections for the state and all counties through 2060. Long-term population projections for the City were not available. Table 2-4 projections indicate a steady decline is set to continue in the overall population of the County. The City’s population trends will likely mirror that of the County.

RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
2-3
Figure 2-1. Wastewater Treatment Facility Service Area
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
2-4
Table 2-3. 2022 to 2030 City of Crescent City Housing Element Update – 2010 to 2019 Population Growth Jurisdiction
2010
Population
2015
Population
Growth Rate
(2010 to 2015)
2019
Population
Growth Rate
(2015 to 2019)
Crescent City 7,676 7,120 -7.25 6,676 -6.25
Del Norte County 28,471 27,788 -2.4% 27,495 -1.1%
Source: U.S. Census Bureau n.d.

Table 2-4 presents the DOF’s population estimates for Del Norte County from 2020 to 2025.

Table 2-4. 2020 to 2025 Population Estimates for Crescent City Year 2020 2030 2040 2050 2060 Annual Growth 2020 to 2060 Del Norte County
Population
27,193 26,750 26,498 25,975 25,720 -0.14%
Source: California Department of finance. Demographic Research Unit. Report P-2A. Total Population Projections, California Counties, 2010-2060 (Baseline 2019 Population Projections; Vintage 2020 Release). Sacramento: California. July 2021.

Based on the City’s declining growth rate experienced between 2010 and 2019 and the DOF’s declining population estimates for the County from 2020 to 2025, the WWTF service area is expected to maintain a stable population for the duration of the 20-year planning period. The projected growth of the City is still within the population projections threshold established in the 2001 General Plan (City 2001), which matches the flows in the existing NPDES permit.

2.4 Design Flows and Loads
The WWTF has been designed and permitted to accept and treat flows of 1.86 MGD at ADWF conditions and 6.12 MGD at average wet weather conditions. These flows are used as the design base for the improvements discussed in this report. To determine projected average day dry weather BOD5, TSS, and ammonia loadings at the design flows, BOD5, TSS, and ammonia concentrations at current conditions were multiplied by projected ADWF. All other projected flow and loads were developed by multiplying the peaking factor presented in Table 2-5 by the design ADW flows and loads. Table 2-6 summarizes the design influent flows and loads.

Table 2-5. Crescent City Wastewater Treatment Facility Upgrade Project Design Flows and Loads Parameter Flow
BOD5
Loading
BOD5
Concentration TSS Loading
TSS
Concentration
Ammonia
Loading
Ammonia
Concentration
Units MGD lb/day mg/L lb/day mg/L lb/day mg/L
ADWF 1.86 4,857 313 4,630 298 499 32.2
MMDWF 3.14 5,687 217 5,628 215 619 23.6
PWDWF 3.33 6,216 224 6,234 225 667 24.0
MMWWF 5.29 5,963 135 6,165 140 533 18.3
PWWWF 6.54 7,111 130 7,354 135 682 12.5
MDWWF 9.02 9,257 123 10,285 137 682 9.1
PHF 14.0 N/A N/A N/A N/A N/A N/A
MDWWF = maximum day wet weather flow
PWDWF = peak week dry weather flow
PWWWF = peak week wet weather flow
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
2-5
Table 2-6. Wastewater Treatment Facility Peaking Factors Peaking Factors Flow TSS load BOD Load Ammonia Load
MMADWW: ADDW 1.69 1.22 1.17 1.24
MMADDW: ADDW 2.85 1.33 1.23 1.07
PDWW: ADDW 4.85 2.22 1.91 1.37
PWWWF: ADDW 3.52 1.59 1.46 1.37
PWDWF: ADDW 1.79 1.35 1.28 1.34
ADDW = average day dry weather
MMADWW = maximum month average day wet weather
PDWW = peak day wet weather

2.5 Plant Performance Evaluation
A whole-plant biological process model developed for the Project Report (Jacobs 2025) was used to evaluate plant performance at the current conditions and design flows with the improvements proposed in this report.

The following treatment scenarios are evaluated using the flows and loads presented in Table 2-5:
 ADWF, with wastewater temperature 21°C
- MBR trains treating primary effluent
- MBR trains treating attached growth effluent (AGE)
 MMWWF, with wastewater temperature 15°C
The MBR trains will treat either primate effluent or AGE. During dry weather conditions, it is recommended to send the primary effluent to the attached growth facility before it goes to the MBR trains. This will reduce the load to the MBR trains, maximizing the bioreactors capacity. It will also help maintain the biofilm at the attached growth facility. During wet weather conditions, the MBR trains and the attached growth system will operate in parallel, both treating primary effluent. Primary effluent flows exceeding the combined MBR capacity will be directed to the attached growth system.

Table 2-7 summarizes the flow split between the MBR trains and the attached growth facility, along with the results for some key operational parameters for each of the scenarios evaluated.

Table 2-7. Plant Performance Evaluation
Parameter MBR Train 1 MBR Train 2 Attached Growth
ADWF (MBR trains treating primary effluent)
PE Flow, MGD 0.8 0.86 0.23
SRT, days 10 10 N/A
ML SS, mg/L 5,100 9,350 N/A
WAS, lb/day 671 696 N/A
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
2-6
Parameter MBR Train 1 MBR Train 2 Attached Growth
ADWF (MBR trains treating AGE)
PE Flow, MGD N/A N/A 1.86
AGE 0.9 0.98 N/A
SRT, days 10 10 N/A
MLSS, mg/L 3,800 7,500 300
WAS, lb/day 500 550 N/A
MMWWF
PE Flow, MGD 1.55 1.52 2.3
SRT, days 13.5 13.5 N/A
MLSS, mg/L 5,000 9,050 185
WAS, lb/day 647 664 N/A
SRT = solids retention time
At the current dry weather average flows and loads, the plant can either use one or both MBR to treat all the influent, allowing the plant operator to take a MBR train offline for maintenance. Under design conditions, the new MBR is expected to provide approximately 1.0 MGD of treatment capacity. The existing MBR has a design capacity of 1.2 MGD ADWF. The combined MBR effluent are projected to have BOD5 and TSS levels of less than 2 mg/L and less than 1 mg/L, respectively.

At the design flow ADWF condition, all influent flow can be treated by the two MBR trains. Under MMWWF conditions, approximately 2.3 MGD (daily average) will be directed to the attached growth and filtration system. The combined MBR effluent and filtered effluent flows are projected to have BOD5 and TSS levels of less than 15 mg/L and 8 mg/L, respectively.

2.6 Hydraulics
The hydraulic calculations for the improved liquid flow stream were completed at the design flow conditions. Figure 2-2 presents the preliminary hydraulic profile, updated for the proposed improvements.

There are multiple facility locations where 2 feet of freeboard is not achievable, given the existing wall heights. The final design will include extending the walls of the existing basins to maintain the minimum freeboard requirements. Appendix D includes hydraulic calculations.

RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
SCREEN
FINE
SCREEN
FINE

UV DISINFECTION

IN-LINE TO REUSE
TANKS (3)

MEMBRANE
PUMPS (2)
REUSE
TANK

FILTRATE

CHANNEL
CL2 CONTACT

STATION

PUMPING

EFFLUENT
PUMPS (3)
FEED
LIQUOR
MIXED

RETURN CHANNEL

HEADWORKS

STATION

PUMPING

INFLUENT

GRIT BASINS

AERATED

CLARIFIERS

PRIMARY

SPLITTER
FLOW

EFFLUENT

PRIMARY
PUMPS (3)
FEED
LIQUOR
MIXED TANKS (3)

MEMBRANE

RETURN CHANNEL
MBR TRAIN 1

ANOXIC AEROBIC
MBR TRAN 2

ANOXIC AEROBIC
PUMPS (3)

FILTRATE
MBR 1
PUMPS (3)

FILTRATE
MBR 2

STORAGE
TO WAS
FILENAME:ANSI_DR.dgn PLOT DATE:31-OCT-2025 PLOT TIME: 22:36 20 25
10 15
20 25
15 10
5 5
10 15
20 25
5 10
15 20
25 5
10 15
20 25
5 10
15 20
25 5
0 -5
-10
0 0
0 -5
-10
FIGURE

HYDRAULIC PROFILE

CRESCENT CITY WWTP
PHASE 1
ANSI_DR.dgn
EL 13.56
EL 23.56T.O.W.

21.27 (0.20)21.29 (1.14)21.34 (3.45)21.42 (8.7)21.44 (10.2) WEIR EL 21.21
EL 11.21

19.87 (0.20)20.35 (1.14)20.81 (3.45)21.99 (8.7)22.37 (10.2) T.O.W. EL 25.5

16.99 (HWL)

CONTROLLEDPUMP
EL 17.71

19.37 (0.48)19.84 (3.44)20.20 (6.45)20.82 (12.5)

20.96 (14)

19.26 (0.48)19.66 (3.44)19.93 (6.45)20.39 (12.5)20.49 (14) EL 19.11

WEIR CREST
CONTROLLEDPUMP18.98 (HWL)
EL 10.21
24" FE
18" FE

OUTFALL
T.O.W.

EL 22.21
EL 18.00
-- (--)-- (--)

20.32 (1.9)19.32 (1.2)
-- (--)
T.O.W. EL 20.48
EL 10.98
21" RS
EL 1.90
EL 0.07
EL -9.10
EL -3.43
16" PI
T.O.W. EL 27.25
EL 23.88

WEIR CREST
EL 14.75
T.O.W. EL 23.00
EL 12.30
EL 18.00

BOTTOM OF RETURN CHANNEL
EL 17.00
EL 20.80

WEIR CREST
EL 17.00
T.O.W. EL 23.25
EL 17.00
EL 21.23
T.O.W. EL 24.00
EL 17.71

WEIR CREST
EL 21.00

BOTTOM OF RETURN CHANNEL
EL 17.00

EL VARIES
-- (0.48)
-1.12 (1.6)-0.47 (5.0)-0.03 (7.8)
-- (14)
-1.53 (1.6)-0.92 (5.0)-0.53 (7.8)
CONTROLLEDPUMP-2.93 (HWL)
-- (--)

23.96 (3.44)24.92 (6.45)25.22 (12.5)
-- (--)
-- (--)

23.44 (3.44)24.91 (6.45)25.21 (12.5)
-- (--)
-- (--)

22.53 (3.44)24.71 (6.45)25.01 (12.5)
-- (--)
NOTE 2 NOTE 3

20.94 (1.6)24.71 (7.8)25.01 (7.8)

20.32 (1.9)19.32 (1.2)

20.15 (1.9)19.40 (1.2)

20.62 (1.2)21.00 (1.9)

19.60 (1.2)19.80 (1.9)

WEIR CREST

21.04 (0.28)

21.14 (2.3)

21.18 (3)

21.68 (3.6)21.99 (3.8)

20.69 (0.28)20.64 (2.3)21.03 (3)21.67 (3.6)21.99 (3.8)
GENERAL NOTES:

HIGH CREST ELEVATION = 24.55LOW CREST ELEVATION = 20.75,

3. ADJUSTABLE WEIR GATE
THAN EL 21.00.MBR FINE SCREEN INFLUENT CHANNEL NO HIGHER

2. MBR FLOW CONTROL GATE MAINTAINS LEVEL IN 1. ELEVATIONS ARE BASED ON AVD 88.

ELEVATION LEGEND:WATER SURFACE

20.13(1.2)20.15 (1.9)

20.12(1.2)20.12 (1.9)

20.15(1.2)20.12 (1.9)

MF (FLOW, MGD)ADWF (FLOW, MGD)AWWF (FLOW, MGD)PHF (FLOW, MGD)IPF (FLOW, MGD) WEIR EL 21.41
-- (--)-- (--)

20.13 (1.2)20.15 (1.9)
-- (--)
-- (--)-- (--)

20.12 (1.2)20.12 (1.9)
-- (--)
-- (--)-- (--)

20.15(1.2)

20.12 (1.9)
-- (--)
EL 17.5
EL 11.21
T.O.W. EL 23.00
-- (--)-- (--)

18.12 (1.2)18.40 (1.9)
-- (--)
-- (--)-- (--)

21.20 (1.2)21.30 (1.9)
-- (--)
-- (--)-- (--)

19.40 (1.2)20.15 (1.9)
-- (--)

FACILITY

TREATMENT
GROWTH

ATTACHED
MM
WEIR EL 22.91

FACILITY

CLOTH FILTER

PUMP STATION

FILTER INFLUENT
EL -2.10
-- (--)

20.74 (1.14)24.10 (3.45)

24.53 (8.7)
-- (--)
3-1

3. Liquid Stream Improvements
The liquid treatment process improvements were selected to address the existing performance and operational challenges and to meet the treatment objectives outlined in Section 2. The proposed treatment process was identified in the Project Report (Jacobs 2025). The proposed liquid stream improvements include the following components:
 Adding a redundant MBR train
 Retrofitting the existing RBC with a new attached growth biological treatment process  Adding cloth media filtration process for the attached growth process effluent before combination with the MBR effluent and chlorine disinfection
 Improving existing primary clarifiers
Figure 3-1 presents the liquid process yard piping plan and explains the operating scheme for various operational sequences depending on influent flow rates. Figure 3-2 presents the process flow diagram for the improved liquid stream process.

Figure 3-1. Liquid Stream Yard Piping Plan, Including Operational Flow Patterns RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design

OVERFLOW

FROM SOLIDS
M
M
DU
(NaOCL)

CHEMICAL
M S

CONTACT TANK

CHLORINE

EFFLUENT PUMPING
18" OUTFALL
24" OUTFALL
TERT
RS RS

REMOVAL
GREASE

GRIT AND

DUMPSTER

CLARIFIER

PRIMARY

DUMPSTER

PUMPING

INFLUENT

SCREENCOARSE

SYSTEMCOLLECTIONFROM
RS
PE
FE
M
PE
PS
TERT

THICKENERTO GRAVITY
TERT

DUMPSTER

WASHING

SCREENINGS
TANKS

MEMBRANE
PUMPS

MBR WASTE

STORAGE TANKTO WAS PUMPS

MBR RECYCLE

RECYCLE ML
WAS
BASIN
ANOXIC
BASIN

AERATION
FIL

STORAGETO WAS
SCREEN TRAIN 1
MEMBRANE BIOREACTOR TRAIN 1

STORAGE TANKTO WAS
FIL
PUMPS

FILTRATE
MBR 1
TANK

MBR FILTRATE
PUMPS
REUSE

STORAGETO WAS

TO REUSE
FIL
M
S
UV

TO REUSE
FILENAME:ANSI_DR.dgn PLOT DATE:31-OCT-2025 PLOT TIME: 21:15 FIGURE

LIQUIDS PROCESS FLOW DIAGRAM

CRESCENT CITY WWTP
PHASE 1
W8Y18700
ANSI_DR.dgn

TREATMENT FACILITY

ATTACHED GROWTH

PUMP STATION

FILTER INFLUENT FACILITY

CLOTH FILTER
M
PUMPS

BACKWASH

CLOTH FILTER

DUMPSTER

WASHING

SCREENINGS
TANKS

MEMBRANE
PUMPS

MBR WASTE
PUMPS

MBR RECYCLE

RECYCLE ML
WAS
BASIN
ANOXIC
BASIN

AERATION
SCREEN TRAIN 2
MEMBRANE BIOREACTOR TRAIN 2
PUMPS

FILTRATE
MBR 2
FIL

FLOW STREAM IDENTIFICATIONSFE FILTER EFFLUENTFIL MBR FILTRATEMBR MEMBRAE BIOREACTORML MIXED LIQUORPE PRIMARY EFFLUENTPS PRIMARY SLUDGETERT TERTIARY EFFLUENTWAS WASTE ACTIVATED SLUDGE

FLOW STREAM IDENTIFICATIONS

INSTANTANEOUS PEAK FLOWRATE IPFPEAK HOUR FLOW PHFAVERAGE WET WEATHER FLOW AWWFAVERAGE DRY WEATHER FLOW ADWFMINIMUM FLOWRATE MF 14 MGD12.5 MGD6.45 MGD3.44 MGD0.48 MGD

RECYCLE FLOWS FROM MBR
FLOW INTO MBR MULTIPLIER1.2 MGD PHF1.9 MGD AWWF
RECYCLE FLOW5.1 MGD4.4 MGD
SYMBOL KEY:

MIXERAUTO SAMPLERMOTORIZED VALVECENTRIFUGAL PUMP
M

VERTICAL TURBINE PUMP
FIL
3-3

3.1 Membrane Bioreactor
A redundant MBR train, MBR Train 2, will be constructed as part of the project. The second MBR train will be in the eastern most secondary clarifier basin. The basin will be divided into four sections to replicate the existing MBR layout: an anoxic zone, an aerobic zone, a mixed liquor (ML) pump station (PS), and membrane trains. Figure 3-3 presents the proposed layout of the proposed MBR facility.

Figure 3-3. Membrane Bioreactor Train 2 Arrangement

3.1.1 Background
The primary goal of an MBR process is to reduce organic matter and nitrogen to levels that comply with the discharge requirements. The plant currently operates with a single MBR train and cannot fully take the system offline for required maintenance. The redundant MBR train will provide redundancy during ADWF conditions and will double the total MBR capacity during wet weather conditions. The additional MBR capacity will allow the plant to achieve effluent limit compliance during the wet weather and peak flow periods.

3.1.2 Process Description
The MBR trains will treat either primate effluent or AGE. During dry weather conditions, it is recommended to send the primary effluent to the attached growth facility before it goes to the MBR trains. This will reduce the load to the MBR trains, maximizing the bioreactors capacity. It will also help maintain the biofilm at the attached growth facility. During wet weather conditions, the MBRs will treat primary effluent. Primary effluent flows exceeding the combined MBRs capacity will be directed to the attached growth system.

Even flow splitting to the two MBR trains will be achieved by using flow control valves and flowmeters upstream of the inlet of MBRs, as shown on Figure 3-3. The MBR influent will go through a band screen installed in the existing clarifier influent channel. Collected screenings will be conveyed to wash presses.

The new MBR will match the configuration of the existing MBR train. This configuration includes a pre-anoxic zone followed by an aerobic zone. The membrane tanks downstream of the bioreactors are aerated to maintain membrane filtration capacity, which is not considered a stage. The aerobic zones accomplish BOD removal and nitrification. The oxygen required for this zone is provided by the aeration system, which consists of diffusers, air piping, flow meters, control valves, and blowers.

RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
3-4
The biological reduction of nitrate to nitrogen gas occurs in the anoxic zones by denitrifying bacteria.

The nitrate produced in the aerobic zones is recycled to the pre-anoxic zones in the return activated sludge (RAS).

ML is pump to the membrane tanks using two pumps at the end of the aerated zone and protected by a baffle wall. The mixed ML from the surface is directed to a surface/scum pump. Surface wasting is advantageous to maintaining good ML filterability, which leads to better membrane performance.

The surface wasting is pumped to the WAS storage tank.

Filtrate is then pumped to a downstream disinfection process. RAS flows by gravity from both membrane tanks into a common RAS channel that is piped to the anoxic zone. A small portion of the ML is directed to the screen influent channel. Rescreening removes stringy solids that have agglomerated within the MBR process from particles originally small enough to pass the screens.

The membrane tanks are aerated during permeate production to maintain membrane productivity.

An additional blower will be added to the existing air scouring system so it can provide the required air to both trains. The anoxic zone is mixed by a propeller mixer. Aerobic zones are aerated and mixed using fine bubble membrane disk diffusers.

3.1.3 Design Criteria
Table 3-1 presents the design criteria for the combined MBR process.

Table 3-1. Membrane Bioreactor Train Capacities
Design Condition Train 1 (existing) Train 2 (proposed) Combined ADWF 1.2 MGD 1.0 MGD 2.2 MGD
MDWWF 1.5 MGD 1.5 MGD 3.0 MGD
Peak Condition 1.9 MGD 1.9 MGD 3.8 MGD
MBR Train 2 will be constructed in the easternmost secondary clarifier. Figure 3-4 presents the proposed piping connections. Table 3-2 presents the additional facility and yard piping required for MBR Train 2.

Figure 3-4. Proposed Membrane Bioreactor Train 2 Process Piping Routes RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
3-5
Table 3-2. Proposed Membrane Bioreactor Train 2 Additional Facility and Yard Piping Needs Flow Stream Material Diameter (inches) Approximate Length (feet) Primary Effluent DIP 20 20
ML DIP 12 70
WAS DIP 4 110
Filtrate 316 SST 6 250
CIP 316 SST 6 85
CIP = clean in place

3.1.3.1 Fine Screening
Fine screening is required upstream of an MBR process to protect the membranes. The proposed MBR Train 2 will use a band screen style fine screen with 2-millimeter perforations to match the existing Train 1 fine screen type. Two additional screens will be provided. One of screens will be dedicated to the new MBR train, while the second one will provide screen redundancy for both MBR trains. A new channel, similar to the secondary clarifier WAS box, will be built for the new MBR train screen, and the existing secondary clarifier WAS box will be modified to accommodate the redundant screen. The clarifier WAS box is in the southeastern corner of the structure, and the new channel will be in the southwestern corner of the structure. The screenings will be washed and compacted before being discharged into a ground level dumpster. Table 3-3 summarizes the design criteria for the fine screen.

Table 3-3. Proposed Fine Screen Design Criteria
Parameter Value
Type Band screen
Number of Screens 2 (1 duty, 1 standby)
Capacity 1.9 MGD
Aperture Size 2 millimeters
Dimensions 6.0 x 2.67 feet
Motor 2 hp (variable speed)
Washwater Supply Flow 2.5 gpm
Washwater Supply Pressure 40 psi
Recommended Products Ovivo (formerly Eimco) CF100, JWC Band Screen Monster Washer Compactor
Type Screw compactor
Number of Compactor 2 (1 duty, 1 standby)
Capacity 36 ft3/h
Motor 2 hp
ft3/h = cubic foot (feet) per hour
gpm = gallon(s) per minute
psi = pound(s) per square inch
RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
3-6

3.1.3.2 Bioreactor
The bioreactor consists of two treatment zones: the anoxic zone and the aeration zone. The anoxic zone will be mixed by a propeller mixer mounted at the south end of the basin. The bottom of the clarifier will be leveled off in the aerated zone to facilitate the diffuser installation.

The aerobic zone will be in downstream of the anoxic zone. Aeration will be provided by 9-inch-diameter fine bubble diffusers installed approximately 1 foot above the floor of the tank. Airflow to the bioreactor will be controlled to maintain a dissolved oxygen (DO) setpoint.

The the surface wasting/scum removal consists of a scum baffle that extends across the water surface of the ML pump channel. This (with the aid of some strategically placed spray nozzles) directs ML/scum through a downward opening weir gate into the surface wasting box at the end of the aerated zone adjecent to the RAS channel, as shown on Figure 3-4. Scum/foam from the MBR tanks will also be collected in the surface wasting pump using a downward opening weir gate mounted in the wall shared with the RAS channel. The surface wasting also has a a submersible recirculating chopper pump, which will pump the WAS/scum to the WAS storage tank. If used strictly to remove scum, the weir is lowered intermittently by an operator, and the surface wasting box is emptied as needed to control the scum.

The plant has had a problem removing the foam that accumulated in the existing MBR train, and an operator at the plant reported that the existing scum pump cannot pump the thick foam. It is recommended to install a scum baffle in the aerobic zone to direct the foam to the scum sump and to replace the existing pump for a submersible recirculating chopper pump.

Table 3-4 summarizes the bioreactor design criteria.

Table 3-4. Proposed Bioreactor Design Criteria
Parameter Value
Minimum 30-Day Average Process Temperature 15°C
Minimum SRT at Maximum Month Winter Loads 13.5 days
Maximum MLSS Entering Membrane Tanks at Maximum
Month Loads
8,500 mg/L
SRT at Maximum Month Loads 9.5 to 13.5 days
MLSS Entering Membrane Tanks at Maximum Month Loads 8,000 mg/L Number of Bioreactors 2 (one existing + one new)
New Bioreactor
Bioreactor Tank Volume 107,000 gallons
Anoxic Zone Volume 18,850 gallons
Side Water Depth 10 feet
Anoxic Zone Dimensions (width x length) 18 x 14 feet
Anoxic Zone Mixer Type Floating
Anoxic Zone Mixer Motor Size 5 hp
Aerobic Zone Volume 70,550 gallons
Aerobic Zone Dimensions (width x length) 18 x 58 feet
Bioreactor Tank Volume 24,600 gallons
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Parameter Value
Bioreactor Tank Length (width x length) 13.5 x 6.9 feet Surface Wasting Pump
Type Submersible chopper recirculating
Number of Pumps 2 duty (one per MBR train)
Flowrate Each 100 gpm
TDH 30 feet
Motor Size 5 hp
TDH = total dynamic head

3.1.3.3 Aeration System
A process blower system will supply air to fine bubble membrane disk diffusers in the aerobic zones of the bioreactors. Two new positive displacement blowers will be installed in the existing MBR Building Blower Room to provide process air to the new MBR train, and one of the existing blowers will provide redundancy for both MBR trains. Air piping from the blower system leads to the bioreactors, where flow splits first to each bioreactor and then to multiple diffuser grids within the bioreactor. Airflow to the bioreactor is controlled to maintain a DO setpoint. Table 3-5 summarizes the aeration system design criteria, and Figure 3-5 presents the proposed blower installation arrangement.

Table 3-5. Process Aeration System Design Criteria
Parameter Value
Number of New Blowers 2 duty (existing blowers will provide redundancy) Type Positive displacement
Capacity (each) 1,400 scfm
Discharge Pressure 5.5 psig
Motor Size 75 hp
Type of Diffusers 9-inch-diameter membrane disk
Number of Discs 750
Recommended Manufacturers Xylem Sanitaire, Environmental Dynamics, Inc., or equal Air Flow Range New Bioreactor 300 to 2,500 scfm
Air Flow Range per Diffuser 0.8 to 4 scfm
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Figure 3-5. Proposed Membrane Bioreactor Blower Arrangement

3.1.3.4 Mixed Liquor Pumps
Two submersible ML pumps will transfer ML from the aeration basin to the membrane tanks for membrane filtration. The pumps will match the design of the existing ML pumps to maintain consistency between equipment manufacturers. The ML pumps will be installed at the end of the aerobic zone and be protected by a baffle wall. There will be two ML pumps, each dedicated to one of the three membrane tanks. Table 3-6 displays the design criteria for the ML PS. A small portion of the pumped ML will be directed to the screen channels for rescreening.

Table 3-6. Mixed Liquor Pump Station Design Criteria
Parameter Value
Number of Pumps 2 duty
Type of Pump Submersible
Flowrate Each 2,600 gpm
TDH 30 feet
Motor Size 30 hp
Discharge Diameter 8 inches
Rescreening Flow 23 gpm

3.1.3.5 Bioreactor Tank Transfer Pump
The two bioreactors for Train 1 and Train 2 will be interconnected with a transfer pump, which is intended to be used to transfer the contents of one train to the other when one train needs to be taken offline.

The transfer pump can also be used to transfer ML from one train to the other during plant upsets.

Table3-7 presents the transfer pump design criteria . The transfer flow path will be selected based on manually actuated valve positioning. The pump will be between the two MBR trains at the deck elevation.

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Table 3-7. Transfer Pump Design Criteria
Parameter Value
Number of Pumps 1
Type of Pump Centrifugal, self-priming
Flowrate Each 300 gpm
TDH 20 feet
Motor Size 20 hp
Discharge Diameter 6 inches

3.1.3.6 Membrane Tanks
The new MBR train includes two independent membrane tanks, each with seven membrane racks within the membrane section of the basin. DuPont (Memcor) membrane equipment will be provided to remain consistent with the existing MBR equipment.

The DuPont membrane modules are assembled onto a rack, and multiple racks are installed into a tank.

The racks are approximately 10 inches wide and designed for individual removal. The modular approach reduces the space requirement for the membrane maintenance and replacement. The head loss through the membranes ranges from 3 psi, which will have a minor impact on the hydraulic profile of the process.

The membrane system uses a CIP procedure that requires sodium hypochlorite and citric acid. The existing MBR uses the same CIP procedure and chemicals. MBR Train 2 will uses the existing CIP storage and pumps. No additional CIP tankage or equipment is required. Table 3-8 presents the proposed membrane design criteria.

Table 3-8. Proposed Membrane Design Criteria
Parameter Value
Number of Membrane Tanks per Train 2
Racks per Tank 7
Modules per Rack 16
Surface Area per Module 538.2 ft2
Dimensions, per Tank (length x width x diameter) 13.5 x 8.9 x 10.1 feet Weight of Membrane Rack 3 tons

3.1.3.7 Filtrate Pump Station
Two filtrate pumps will be provided by DuPont to maintain consistency with existing equipment. The pumps will be 10-hp end suction centrifugal pumps. The pumps will be installed adjacent to the existing filtrate pumps in the MBR building. One pump will be dedicated to one membrane tank. The pump suction will tie into the eastern side of each membrane tank with 8-inch-diameter pipe, matching the design of the existing train. The two pump discharges will combine into the existing 10-inch-diameter discharge header, which ties into the filtrate tank. The filtrate tank overflows into the effluent channel, where effluent flows by gravity to the chlorine contact basin or is pumped to the onsite reuse system. Each filtrate pump will be monitored by a turbidimeter to report individual tank MBR effluent turbidity to SCADA. Table 3-9 presents the design criteria for the filtrate pumps. Figure 3-6 shows a schematic of the proposed piping installation.

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Table 3-9. Filtrate Pump Design Criteria
Parameter Value
Number of New Pumps 2 duty
Type of Pump Centrifugal
Flowrate Each 694 gpm
TDH 29 feet
Motor Size 10 hp
Figure 3-6. Filtrate Pumps for Membrane Bioreactor Train 2 Proposed Location

3.1.3.8 Air Scour Blowers
The membranes have an air scour system to clean the membranes between CIP procedures. There will be one additional blower required for the two membrane trains. This equipment will be provided by DuPont to match the existing. The new blower will be in the blower room of the MBR building and will be tied into the existing air piping (Figure 3-5). The air piping will branch off the existing line on the north side of the MBR facility and mirror the existing train. The new air scour blower will be a 40-hp positive displacement blower. Table 3-10 presents the operating requirements for the air scour blowers.

Table 3-10. Air Scour Blower Operating Requirements
Parameter ADWF Peak Hour
Total Demand Airflow Rate (scfm), Train 2 918 1,740
Air Demand per Basin, Airflow Rate (scfm) 153 290
Discharge Pressure (psig) 4.6 4.7
Power (hp) 40
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3.1.4 Structural Improvements
Existing wood-framed walkways and railings will be demolished. A new walkway will be constructed using aluminum framing, grating, and guardrail between the MBR and the cloth filters above the process piping.

New reinforced concrete walls and channels needed for the MBR basins will be designed. Because of the small amount of horizontal reinforcing in the existing walls, the connections for the new walls will be designed so as not to transfer axial forces into the new walls from differential fluid pressures on the existing walls to reduce the horizontal bending induced in those walls. The existing basin walls will be used to provide out-of-plane support to the new walls because of differential fluid pressures and hydrodynamic demands from seismic loading.

3.1.5 Instrumentation and Controls
Except for surface wasting, process controls will be designed to match the existing MBR design. Controls that coordinate multiple membrane tanks will be expanded to include MBR Train 2. Any obsolete PLC equipment associated with a master control panel (MCP) or local control panels (LCPs) will be upgraded by the supplier.

3.2 Attached Growth Treatment Facility
The biological treatment train of the combined MBR trains is inadequate to treat peak flows. Instead of installing additional MBR capacity to treat peak flows, a separate biological and filtration process will be provided to replace the capacity of the failing RBCs. The replacement process will be an attached growth system for biological treatment, followed by cloth media filtration.

To maintain the biological colonies during low flow periods, the influent flows will be diverted through the attached growth process before the MBR process. This will benefit the process by reducing the biological loading to the MBRs and allowing the attached growth facility to remain online during low flow periods.

3.2.1 Background
The existing RBC facility has recurring mechanical issues. As of March 2025, 4 of 12 RBC units were permanently offline because of mechanical issues. The remaining eight RBC units cannot provide the required treatment performance, resulting in high suspended solids in the clarified effluent. The Project Report (Jacobs 2025) recommended replacing the existing RBCs with an attached growth system provided by WavTex. This system uses a moving woven media fixed-film mounted within modular frames.

The frames contain integrated aeration by fine bubble diffusers. WavTex modules are designed to be installed in an open channel with multiple units arranged in series. The footprint of the WavTex modules will fit within the existing available footprint within the RBC channels.

3.2.2 Design Criteria
Once the existing RBC mechanical equipment is demolished, the three existing RBC trains will be converted into three open channel attached growth trains outfitted with WavTex units by Entex. Table 3-11 presents the design criteria for the attached growth system.

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Table 3-11. Attached Growth Facility Design Criteria
Parameter Current Conditions Ultimate Buildout
Number of Trains 2 3
Modules per Train 8 8
Total number of Modules 16 24
Total Treatment Capacity (MGD) 1.5 2.3
BOD treatment capacity (lb/day) 1,000 1,500
Solids Yield (lb/day) 337 N/A
Minimum Flowrate (MGD) 0.15 0.23
Media Area per Module (ft2) 2,320 2,320
Airflow Requirement per Module (scfm) 134 134
Total Airflow Requirement (scfm) 2,144 3,216
Number of Blowers 2 (1 duty + 1 standby) 3 (2 duty + 1 standby)

3.2.3 Process Description
Under normal operating conditions, primary effluent flows exceeding the combined MBR capacity will be directed to the attached growth system. A minimum flow of 0.23 MGD through the system is required to support the biofilm in two channels. Existing yard piping from the primary clarifiers to the RBC facility will be used to transfer the desired flows. Figure 3-7 presents the WavTex arrangement and proposed air piping network. Red indicates current condition capacity, and blue is for ultimate buildout capacity.

The process blowers will be installed at the dewatering building in the place of the old RBC blowers, as shown on Figure 3-7. New air header piping will connect the process blowers to the facility.

Figure 3-7. Attached Growth Facility Arrangement
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The existing air piping will be replaced with larger diameter pipe to accommodate the higher air demands.

Associated isolation valves and dampers will be provided in the design. Drain piping will be provided to flush condensate from the air piping.

Table 3-12. Approximate Additional Piping
System Material Diameter (inches)
Approximate
Length (feet)
Air Supply from Blowers to Air Header SST 20 180
Air Supply to WavTex Units from Air Header SST 8 200

3.2.4 Structural Improvements
Demolition of existing RBC equipment will be performed, with concrete removal included where equipment pads are not reused. New equipment pads will be provided with sufficient thickness to anchor the equipment in accordance with the CBC under Risk Category IV.

New pipe supports will be designed to the requirements of Risk Category IV, with a component importance factor used to increase the seismic forces to produce essentially elastic performance under the maximum considered earthquake for the project site.

3.2.5 Instrumentation and Controls
The attached growth system air supply will be manually controlled, with remote operator controls provided through SCADA. A DO sensor per train will be provided to monitor the DO and manually adjust the blower operation. Loop control using DO sensors will not be provided because it is anticipated the air demand through the attached growth system will be relatively constant.

3.3 Cloth Media Filtration
AGE will be filtered through cloth disk filters before disinfection. However, effluent from the attached growth facility will be diverted to the MBR trains during ADWF flow periods.

3.3.1 Background
Cloth filtration will be used to reduce total suspended solids (TSS) concentrations from the AGE. The cloth disk filter process will be in the center existing secondary clarifier basin. This basin will be modified to accommodate a filter influent PS, two disk filter units, backwash pumps, and associated piping.

The backwash pumps will sit inside the basin, north of the effluent channel, and will be fed by the valve assembly under the disk filter arrangement. Figure3-8 shows the proposed layout of the filtration facility.

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Figure 3-8. Cloth Filter Facility Layout

3.3.2 Process Description
Cloth media filters use a series of partly submerged, rotating, vertical disks that support the filter cloth.

The vertical orientation allows for a large amount of filter area in a small footprint. AGE will flow by gravity into the filter influent PS wet well. Flows up to 2 MGD can be conveyed by gravity through the filtration system. During peak flow conditions, the flows will be boosted by the filter influent PS to feed the common influent header of the cloth disk channels. Flows will be equally split between the two filter trains if both trains are online. Filtered effluent will be combined in a shared effluent header and flow by gravity into the chlorine mixing chamber, where it will combine with the MBR effluent.

3.3.3 Design Criteria
The cloth filter facility includes a filter influent PS and two cloth disk filter trains. The facility will convey filtered effluent to the existing chlorine contact basin for disinfection.

3.3.3.1 Filter Influent Pump Station
The cloth disk filters will require an influent PS to convey flows during peak flow conditions. The PS will be in the middle secondary clarifier basin, upstream of the disk filters. A new wall will be constructed to create the wet well for the PS. The wet well will be fed by the existing pipe network. Figure 3-9 and Figure 3-10 show the proposed layout of the PS in plan and section, respectively.

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Figure 3-9. Filter Influent Pump Station Plan
Figure 3-10. Filter Influent Pump Station Section
The pumps will be used when the flow to the filters reaches 2 MGD. Table 3-13 shows the design criteria of the pumps.

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Table 3-13. Pump Station Design Criteria
Parameter Value
Type Submersible
Number of Screens 3 (2 duty, 1 standby)
Drive Variable frequency
Primary Flowrate 3,000 gpm
Primary Dynamic Headloss 15 feet
Secondary Flowrate 1,390 gpm
Secondary Dynamic Headloss 5 feet
Table 3-14 presents the approximate pipe length to support the proposed facility.

Table 3-14. Filter Influent Pump Station Piping
System Material Diameter (inches) Approximate Length (feet) Pump Discharge DIP 10 20
Filter Influent DIP 20 35

3.3.3.2 Cloth Disk Filters
Cloth filters can be provided in two configurations: inside-out and outside-in. The outside-in configuration was selected for this project because of the low headloss across the system. Channel-mounted filters are recommended because of concerns with corrosion in the corrosive environment and material costs with the stainless-steel container design. The channel-mounted type would include constructing new walls within the clarifier, which will separate the trains and elevate the walls around the filters.

Table 3-15. Cloth Filter Design Criteria
Parameter Value
Filter Type Cloth media filters
Style Channel mounted
Number of Filter Units/Disks per Unit 2 duty
Single Disk Area 36.6 ft2
Filter Dimensions (length by width) 15.5 x 7.5 feet
Maximum Hydraulic Surface Loading 5.85 gpm/ft2
Solids Loading Rate 2.32 lb TSS /day/ft2
Target Effluent TSS 5 mg/L
Minimum Flow 0.2 MGD
Total Capacity 8.64 MGD
Maximum Head Loss 0.5 feet
Pore Size 5 µm
Filter Drive Motor 460 V/3-phase, 1 hp
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Parameter Value
Number of Backwash Pumps 3 (2 duty + 1 standby)
Maximum Backwash Flow per Pump 100 gpm
Backwash Pump Motor 460 V/3-phase 2 hp
Recommended Products Beacon G-Disks, Aqua Aerobics Aqua Disks µm = micrometer(s)
V = volt(s)
Figure 3-11 shows a section view of one filter train, including elevation data.

Figure 3-11. Section of Cloth Filter Facility
Each filter is equipped with level and vacuum instrumentation. The filter drive motor will rotate the disks.

The backwash pump will pull a vacuum through the backwash piping, which will vacuum the deposited solids from the surface of the cloth media and transfer it to the plant drain system. Filter backwash is automatic and based on water level differential or a timer setpoint. The filter maintains continuous operation during backwash. Backwash flows are supplied by filtered effluent. Typical backwash recovery rates are 1 to 4 percent of filter throughput. Backwash waste from the filtration process, which is expected to contain less than 1,500 mg/L of solids, will be conveyed to the plant drain. Each filter train has an overflow weir that discharges to the effluent channel.

Table 3-16 presents the piping required to support the proposed facility.

Table 3-16. Additional Piping Requirements for Filter Facility System Material Size (inches) Approximate Length (feet) Filter Effluent Ductile iron 20 90

3.3.4 Structural Improvements
New reinforced concrete walls will be constructed for the cloth disk channels and the filter influent PS wet well. As with other structural work in the existing structure, connections of the new walls will be designed to limit high stresses from occurring in the existing walls where the original design provided minimal reinforcing for resistance. Additionally, the existing filtrate channel will be sealed off with a concrete wall.

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Concrete framing will be added to support the cloth filters in the subdivided basin. The support systems will be designed to not overload the existing base slab and walls under operating and seismic load conditions.

3.3.5 Instrumentation and Controls
Each filter will be provided with a packaged local control panel that contains all necessary control and monitoring for the system. This includes operator interfaces, displays, relay logic, timers, alarms, and contacts for remote monitoring. Motor starters for the backwash pumps will be provided in each local panel.

The filter backwash is automatically initiated based on water level differential or a timer. Continuous filtration is maintained throughout the backwash process. The backwash discharge flow is monitored through SCADA.

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4. Solids Handling Improvements
The biosolids treatment method at the City WWTF includes separate primary sludge and WAS thickening, combined anaerobic digestion, followed by dewatering then hauling to landfill disposal. The upgrade project includes several critical improvements to stabilize and enhance biosolids treatment performance, improve process control, and enable compliance with both current federal regulations and future state mandates.

The upgrades are designed to preserve operational flexibility while improving volatile solids reduction, providing stable biosolids handling and disposal operations using the current biosolids handling process.

The proposed solids handling improvements consist of the addition of separate WAS and digested sludge (DS) storage and pumping facilities and rehabilitation of the existing GT and anaerobic digesters.

Figure 4-1 shows the updated process flow diagram for the solids handling facilities.

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Figure 4-1. Proposed Solids Process Flow Diagram
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4.1 Waste Activated Sludge and Digested Sludge Storage and Pump Gallery
WAS and DS storage will be provided to help attenuate peak loading to the RDT and improve the operational flexibility of the RDT, anaerobic digesters, and dewatering facility. The ideal operating condition for anaerobic digestion is for constant feed and withdrawal. WAS storage will allow for variable wasting from the MBRs while maintaining a constant feed rate to the RDT and the anaerobic digesters.

The DS storage volume will provide a buffer for the dewatering activities to allow for constant withdrawal from the digester and a 5-day per week dewatering operation schedule.

The western secondary clarifier will be retrofitted into three independent sections, one open-aired basin for WAS storage, one covered basin for DS storage, and one covered section as a pump gallery, which will house the associated equipment.

Figure 4-2 presents a plan view of the proposed facilities.

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Figure 4-2. Waste Activated Sludge and Digested Sludge Storage Facilities RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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4.1.1 Process Description
This section describes the WAS and DS storage process.

4.1.1.1 Waste Activated Sludge Storage
WAS flows from the MBRs vary throughout the day because of the CIP maintenance activity of the membrane rack channels. It is recommended to have a WAS storage facility to provide a buffer from the fluctuating WAS flows to the feed flows to the RDT and therefore the anaerobic digesters to maintain a constant feed rate to the digesters.

WAS will be pumped to the storage facility using the existing MBR WAS pumps. Minor modifications will be made to the existing 8-inch-diameter WAS piping to connect to the existing 10-inch-diameter secondary clarifier influent header to the storage basin. WAS will be discharged by the existing secondary clarifier WAS pumps to rejoin the 8-inch-diameter WAS pipeline to the RDT.

The WAS storage basin will be open to atmosphere and aerated to prevent solids settlement from providing oxic conditions. The aeration target DO concentration is 1.0 mg/L, which will reduce odor-related issues.

4.1.1.2 Digested Sludge Storage
DS storage will provide operational flexibility for the dewatering operations. The dewatering schedule is dependent on the haul truck pickup times; a truck must be parked in the dewatering facility load-out bay for the dewatering facility to be operational. Additionally, operations schedule does not allow for weekend or holiday dewatering. To provide a constant feed and withdrawal rate from the digesters over weekend and holidays, the DS storage volume is sized for 3 days. Mixing will be provided to limit settling. The DS storage basin will be covered, which will limit odor wafting.

DS will be pumped to the storage basin by a new DS pump, which will be at the digester building. One of the three existing pumps will be replaced with a smaller pump that is solely dedicated to DS transfer because of the low flowrates necessary to maintain constant flows into and out of the digesters. Stored DS will be transferred to the dewatering facility by a new solids PS in the pump gallery.

4.1.2 Design Criteria
The design criteria for both basins and the pumping facilities are presented in the following subsections.

4.1.2.1 Waste Activated Sludge Storage
Table 4-1 presents the minimum dimensions, solids concentration, and retention time for the WAS storage facility.
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Table 4-1. Waste Activated Sludge Storage Facility Design Conditions Parameter Value
Volume 25,000 gallons
Days of Storage 1
Dimensions (L x W x D) 25 x 18 x 11.5 feet
Minimum Freeboard 2 feet
Influent Solids Concentration 1%
Aeration or Mixing Required Both, 1.0 mg/L DO minimum
Mixing Energy 0.04 hp/1,000 gallons[a] (1 hp)
Aeration Requirement 20 scfm/1,000 ft3 (62 scfm)
[a] Based on standard from Water Environment Federation (WEF) Design of Water Resource Recovery Facilities, Manual of Practice 8, 7th Edition (2025).
ft3 = cubic foot (feet)
hp = horsepower
scfm = standard cubic foot (feet) per minute

4.1.2.2 Digested Sludge Storage
Table 4-2 presents the minimum dimensions, solids concentration, and retention time for the DS storage basin.

Table 4-2. Digested Sludge Storage Design Criteria
Parameter Value
Volume 38,000 gallons
Days of Storage 3
Dimensions (L x W x D) 40 x 18 x 11 feet
Minimum Freeboard 2 feet
Influent Solids Concentration 3%
Aeration or Mixing Required Mixing only
Mixing Energy 0.04 hp/1,000 gallons[a] (1.5 hp)
[a] Based on standard from WEF Design of Water Resource Recovery Facilities, Manual of Practice 8, 7th Edition (2025).

4.1.2.3 Pumping Facilities
Two PSs require improvements for the DS storage facility. One is the existing DS PS at the digesters.

The second PS will be in the pump gallery and will be called the stored solids (SS) PS.

Table 4-3 presents the design criteria for the DS PS. The pump discharge rate from the DS PS coupled with the new 4-inch-diameter pipe generates a velocity of 0.3 foot per second (ft/s). Low flowrates, below 2 ft/s, can lead to solids deposition in the pipe. Solids deposition causes increased energy consumption, and it increases the risk of pipe failure. It is recommended to install a flushing connection to the transfer piping to prevent clogging. The flushing will discharge into the DS storage, which will be further explained in Section 5.

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Table 4-4 presents the design criteria for the SS PS station.

Table 4-3. Digested Sludge Pump Station Design Conditions Parameter Value
Flow Path Anaerobic digester to DS storage basin
Daily Transfer Volume 12,015 gallons
Transfer Flow Rate[a] 8.5 gpm
TDH <5 feet
Pump Type Progressive cavity
Pipe Diameter 4 inches
Velocity 0.3 ft/s[a]
[a]
24 hours per day, 7 days per week operation for constant digester elevation Table 4-4. Stored Solids Pump Station Design Conditions Parameter Value
Flow Path DS storage basin to dewatering facility (BFP) Hours of Operation 7 hours, 5 days per week
Flow Rate Conditions Minimum Condition: Average daily drawdown of storage basin Peak Condition: Dewatering equipment capacity
Flow Rate Range 30 to 100 gpm
TDH 19 feet
Pump Type Progressive cavity
Number of Pumps 1 duty, 1 standby
Horsepower 10 hp
Pipe Diameter 4 inches
Velocity 2.5 ft/s

4.1.3 Alternatives Discussion
The following subsections discuss the alternatives.

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4.1.3.1 Waste Activated Sludge Mixing/Aeration Alternatives The WAS storage will be aerated to prevent septic conditions. Mixing is recommended to prevent solids settling in the tank. Four combination mixing and aeration alternatives were considered for the WAS storage: surface aerators, hybrid mixing aerator, jet aerators, and coarse bubble (CB) diffusers. The four alternatives are further described as follows:
 Alternative 1 – Surface Aerators: Alternative 1 is to install either floating or wall-mounted surface aerators. Surface aerators work by splashing the surface liquid and making the liquid capture the air on its way down. This creates vertical circulation, which keeps solids suspended and provides uniform oxygen distribution throughout the storage area. Surface aerators can struggle with maintaining solids in suspension in deeper storage tanks. The aerators can also be equipped with mixers. This would be beneficial to reduce energy requirements if the system is mixing limited rather than aeration limited.  Alternative 2 – Hybrid Mixer Aerator: These systems use both fine bubble aeration and an impeller or paddle to keep the system well mixed and aerated. These provide less aeration than surface aerators or jet mixers, but this is not much of a concern because the only reason for aerating is for odor control.  Alternative 3 – Jet Aerators: Jet mixer aerators are installed at the bottom of the basin and use an external pump to draw in air and eject it at a high velocity into the WAS. This creates fine bubbles that both agitate and aerate the basin. Jet mixers excel with horizontal mixing. The pumps can either be in a dry area or be submersible. The pumps in a dry area are easier to maintain but may limit the amount of space left for the DS transfer pumps in the pump gallery. The submersible pumps would require davit cranes, or similar lifting devices, and an area for the operators to pull the pump out. The submersible pumps are recommended because of the limited space in the pump gallery.  Alternative 4 – Coarse Bubble Diffusers: CB diffusers are installed at the bottom of the storage and release large air bubbles. The air bubbles create a strong vertical mix as they rise through the WAS, keeping the solids well mixed. CB diffusers require an external blower to provide energy for the system.

These blowers are typically not submersible and would have to fit within the new pump gallery.  Table 4-5 lists the benefits and limitations of each alternative.

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Table 4-5. Waste Activated Sludge Storage Combination Mixing and Aeration Alternatives Alternative 1 – Surface Aerators
Alternative 2 –
Hybrid Mixer Aerator
Alternative 3 –
Jet Aerator
Alternative 4 –
Coarse Bubble Diffusers
Benefits  Effective and common
technology for WAS aeration
 Easy operation and maintenance
 Low maintenance costs
 Do not require additional space
because they fit directly into the
basin, as opposed to the
diffusers, which require space
for the blowers
 Lowest capital costs
 Energy efficient
 Smaller footprint by
combining two technologies
together
 Do not require additional
space because they fit directly
into the basin
 Easy operation and
maintenance
 Strong horizontal mixing
 Easy operation and
maintenance
 Submersible or dry area
pump
 Strong vertical mixing
 Low chance of clogging
or fouling
Limitations  Aerators/mixers may be less
efficient or ineffective if the WSE
varies too much
 Not as efficient in deep basins
 Higher capital cost than
surface aerators
 Lowest oxygen transfer
efficiency
 Potential clogging of
nozzles
 Higher capital costs than
surface aerators
 Decreased oxygen
transfer efficiency in
thickened sludges
 Require blowers to be
in the pump gallery,
which has limited space
WSE = water surface elevation
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The recommended mixing and aeration solution is jet aerators. These aerators have a strong performance record for this application and will be able to provide the required air and mixing for the system.

The decreased oxygen transfer efficiency is not a concern in this system because the sludge has not yet been thickened. Additionally, these aerators can be installed within the storage basin, freeing up space in the pump gallery, which is a significant advantage because of the space constraints within the clarifier.

While the surface aerators are the cheapest alternatives, they require dropping the WSE by at least 3 feet to ensure solids suspension throughout the bottom portion of the basin. This adds complexity to the system, and if not done regularly ,then significant solids deposition may occur. Table 4-6 shows the design conditions of the jet aerators.

Table 4-6. Jet Aerator Design Criteria
Parameter Value
Number 2 (1 duty, 1 standby)
Horsepower, each 15 hp
Nozzles, each 1
Aeration Depth 9.5 feet
SOTR 32 lb O2/h
Recommended Manufacturers and Models FLYGT Jet Aerator Model JA-117-3153 lb O2/h = pound(s) of oxygen per hour
SOTR = standard oxygen transfer rate

4.1.3.2 2Digested Sludge Mixing
Two mixing alternatives were considered for the DS storage basin: hydraulic sludge mixers and mechanical mixers. The two alternatives are described as follows:
 Alternative 1 – Hydraulic Sludge Mixers: Alternative 1 is to use a recirculation pump with hydraulic sludge mixers to provide complete mixing in the DS storage. The recirculation pump pulls the sludge from the tank, pressurizes it, and then discharges it at a high velocity through jet nozzles. This creates momentum in the tank and thus mixes the sludge. The pump must be in a dry area outside of the tank.

This makes it easier to maintain but means that a separate area must be provided. A pump gallery is recommended to provide a dry area for the hydraulic mixers’ recirculation pump. This space can also be used to house any pumps needed for aeration and mixing in the WAS storage or for the DS transfer pumps.  Alternative 2 – Mechanical Mixers: Alternative 2 is mounted mechanical mixers. The motor is mounted at the top, and the mixers can be attached to the side walls of the storage. There can be impellers added at multiple locations of the shaft, allowing for mixing throughout the vertical height of the basin.  Table 4-7 lists the benefits and limitations of each alternative.

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Table 4-7. Digested Sludge Storage Mixing Alternatives
Alternative 1 – Hydraulic Sludge Mixers Alternative 2 – Mechanical Mixers Benefits  No moving parts within the basin leads
to less equipment maintenance
 Effective mixing across entire storage
 Common and proven technology
 Easy maintenance
 Simple system—low capital costs
 Effective mixing near impellers
 Mixing intensity is easily controlled
 Clogging is highly unlikely with proper
functioning headworks
 All equipment can fit within the storage
and does not require additional area
Limitations  Additional dry area for recirculation
pump
 Lowered performance with thicker
solids (>2%)
 Potential abrasion of nozzles over time
 Higher capital costs
 Need multiple mixers to ensure entire
basin is well mixed or else dead zones
may occur
 Maintenance would be difficult because
of accessibility
 Abrasion from high solids
 Providing an effective gas seal can be
difficult
The recommended mixing system is the hydraulic sludge mixer. This is a proven sludge mixing technology that is easy to maintain and has low energy consumption. The adjacent pump gallery will house the pump equipment used for the mixing system. This area will be easy to access for maintenance compared to internally mounted mixing equipment in the DS storage basin. Table 4-8 shows the hydraulic mixer design criteria.

Table 4-8. Hydraulic Sludge Mixer Design Criteria
Parameter Value
Number 2 (1 duty, 1 standby)
Pump Flow 686 gpm
Pump TDH 26 feet
Pump Horsepower 10 hp
Number of Nozzles, each 2
Manufacturer and Model Hayward Gordon Hydromix System

4.1.4 Instrumentation and Controls
New instrumentation will be provided to monitor and control the process, including flow meters, level instruments, pressure, and others as needed. The jet aerators will be controlled by a DO sensor, which will maintain a minimum of 1.0 mg/L to prevent anoxic conditions.

4.1.5 Pump Gallery HVAC and Odor Control
Heating and ventilation direction for the pump gallery will be provided. Wall-mounted louvers with motorized dampers and fans with backdraft dampers will provide natural cooling and ventilation using ambient air. Unit heaters will be used for heating. Fans and associated ductwork will be sized for 6 ACH, in accordance with National Fire Protection Association (NFPA) 820 requirements. Louvers will also be sized for the requisite volume of air with an intake face velocity of no greater than 400 feet per minute based on free area of the louvers.

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The storage facilities are not anticipated to have strong odor, but it is recommended to cover the DS storage facility and provide passive ventilation. There are many cover material options, including fiberglass-reinforced plastic (FRP), aluminum, or concrete. However, covering the DS storage will make it an enclosed space. A small corrosion-resistant louver (12 inches by 12 inches) will be installed to allow for air movement when the storage volume changes.

4.1.6 Structural Improvements
Two 12- to 16-inch walls must be constructed between the basins to separate the WAS storage and the DS storage and pump gallery. The structural details for this design will be detailed during final design.

The DS basin and the pump gallery will both be covered to prevent rainwater intrusion into the basins.

Stairway access will be designed for the pump gallery because frequent operator access is expected.

Two roof hatches will be sufficient for access into the DS storage basin because maintenance access is only anticipated for periodic cleanings. During these events, the space will be an OSHA-confined space, and additional air circulation will be required.

4.1.7 Corrosion Control
The recommended corrosion-resistant coating (CRC) for the DS storage basin interior concrete includes robust, high-build, immersion-capable epoxy formulations engineered to withstand the harsh conditions typical of these environments. The CRC system is detailed as follows:
 Primer: One coat of manufacturer’s recommended moisture-resistant epoxy primer, 2 millimeters minimum dry film thickness (MDFT), as required by CRC manufacturer  Surfacer/Filler: One coat of 100% solids, trowel applied epoxy surfacer, application rate as required to fill and level 100% of the concrete surface in preparation for coating, 1/16-inch nominal thickness  Corrosion Barrier Lining: One coat of trowel grade, 100% solids, chemical-resistant amine-cured epoxy lining material, 125 MDFT
 Glaze Coat: Required for fiber-filled or aggregate-filled corrosion barrier lining products to provide a smooth surface; one coat of liquid applied, 100% solids, amine-cured chemical-resistant epoxy finish, 15 to 20 MDFT
For pipe interiors exposed to substantial headspace or elevated corrosion risk, epoxy ceramic linings are strongly recommended over cement linings to provide an additional protective barrier. In cases requiring high abrasion resistance or improved flow smoothness, glass linings are recommended.

Additional protective measures are generally unnecessary for the interior surfaces of 316 stainless steel because of its inherent corrosion resistance. However, the maximum safe chloride concentration for 316 stainless-steel alloys is approximately 1,000 parts per million (ppm).

When selecting valve materials, long-term durability and resistance to the operational environment should be prioritized. Corrosion-resistant materials, such as 316 stainless steel, typically do not require supplemental protection when submerged in environments with chloride levels below the permissible threshold. In contrast, iron and steel pipes should be protected with durable epoxy coatings designed for harsh conditions.

It is recommended that the at-grade level covers be constructed from ultraviolet (UV)-resistant FRP to ensure long-term durability and protection against sunlight exposure.

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4.2 Gravity Thickener
The GT is a circular basin with a mechanical mechanism in the center that slowly rotates to transfer thickened sludge collected at the bottom of the basin to the center pipe to feed the anaerobic digesters.

Supernatant is decanted from the top of the basin and is returned to the liquid treatment process at the headworks. The GT thickens sludge from the primary clarifiers before anaerobic digestion. The GT has reached the end of its useful life and needs to be fully rehabilitated by replacing all mechanical equipment, adding covers, and recoating the interior surface.

4.2.1 Background
The GT was constructed as part of the 1973 Water Pollution Control Plant Modifications. It is 20 feet in diameter with a 10-inch wall and an exterior launder. A wood cover was placed over the GT as part of the 1977 Phase II Additions, which was later removed. A new cover is desired to limit the odor coming from the primary thickened sludge.

4.2.2 Design Criteria
Table 4-9 provides the design criteria for the mechanical rehabilitation of the GT.

Table 4-9. Gravity Thickener Facility Design Conditions Parameter Value
Diameter 20 feet
Depth 9 feet
Mechanism Type Center mechanism
Cover Type Under walkway flat cover

4.2.3 Rehabilitation Description
The GT must be fully rehabilitated because major mechanical equipment is clearly corroded, and the walls require complete recoating. The existing mechanism will be replaced. Table 4-10 presents the design criteria for the new replacement equipment .

Table 4-10. Gravity Thickener Mechanism Design Criteria Parameter Value
Diameter 20 feet
Depth 9 feet
Drive Horsepower 0.5 hp
Drive Voltage 480 V
Potential Manufacturer Clear Stream Environmental
The walkway over the center of the GT will be replaced. New FRP flat covers will be placed on each side of the walkway over the liquid surface. The cover will have removable panels for necessary inspection and cleaning of the GT. The cover will not be airtight and will allow for airflow between the walkway and the cover edge opening. Removable panels will be incorporated into the cover design for maintenance access and visual inspection.

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4.2.4 Instrumentation and Controls
New instrumentation will be provided to monitor and control the new process equipment as required.

No new process controls, including flow meters, level and pressure instruments are included in the design at this time.

4.2.5 Corrosion
The 2021 assessment revealed that several interior concrete surfaces show signs of wear and paste loss, indicating the need for repair and resurfacing. This deterioration is likely caused by a combination of biogenic sulfide corrosion and exposure to abrasive media streams. To prevent further degradation, it is recommended that a CRC be applied to the resurfaced concrete surfaces, thereby protecting the new cementitious matrix. The CRC components will consist of the following:
 Primer: One coat of manufacturer’s recommended moisture-resistant epoxy primer, 2 millimeters MDFT, as required by CRC manufacturer
 Surfacer/Filler: One coat of 100% solids, trowel applied epoxy surfacer, application rate as required to fill and level 100% of the concrete surface in preparation for coating, 1/16-inch nominal thickness  Corrosion Barrier Lining: One coat of trowel grade, 100% solids, chemical-resistant amine-cured epoxy lining material, 125 MDFT
 Glaze Coat: Required for fiber-filled or aggregate-filled corrosion barrier lining products to provide a smooth surface; one coat of liquid applied, 100% solids, amine-cured chemical-resistant epoxy finish, 15 to 20 MDFT
Given that the GT mechanism is in poor condition, the submerged portions of the gravity mechanism should be replaced with stainless steel. If carbon steel is considered because of cost constraint, the carbon steel should be coated with an amine-cured chemical-resistant epoxy and cathodically protected with sacrificial anodes. All submerged mechanism fabrications must be fully seal welded to prevent crevice corrosion; no skip welds will be allowed.

It is recommended that the at-grade level covers be constructed from UV-resistant FRP to ensure long-term durability and protection against sunlight exposure.

4.3 Anaerobic Digestion
Two anaerobic digesters receive thickened solids flows from the GT and the RDT. Several key features and pieces of equipment in the digesters are failing or inadequate. The floating covers of both digesters have severe corrosion, with the oldest digester cover (Digester 2) having material failure where digester gas can freely escape. The rollers and guides for the floating covers are out of alignment, bent, and corroded, and the covers have tipped in the past. The biogas is currently being sent to either the digester boiler or a flare.

The boiler that provides process heating for the digesters is at the end of its expected life and is difficult to keep operational. No redundant boiler is available.

4.3.1 Background
Digester 1 and the digester building were constructed as part of the 1977 Phase II Additions. The digester has a floating cover supported on corbels off the 10-inch wall. Digester 2 was constructed as part of the original plant construction and has a floating cover. Wall thickness at this digester is 9 inches at the top and 12 inches at the bottom.

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4.3.2 Design Criteria
Table 4-11 provides the digester facility design conditions.

Table 4-11. Anaerobic Digester Facility Design Conditions Parameter Value
Design Sludge Flow Rate 12,015 gpd
Heating Design Point 98°F
SRT 20 days[a]
Boiler Capacity 452,000 Btu
[a] At Design ADWF
°F = degree(s) Fahrenheit
Btu = British thermal unit(s)
gpd = gallon(s) per day

4.3.3 Process Description
It is recommended to change the digester operation from in series to in parallel. The primary digester will be fed thickened sludge from the GT and the RDT at a constant flow rate. The DS from the secondary digester will be pumped at a constant rate to the DS storage basin. It is anticipated that the existing equipment can accommodate these operational changes. The upgrades required for the pumping facilities in relation to this operational change are described in Section 5.3.1.

4.3.4 Digester Rehabilitation
The digester rehabilitation details are provided in the following subsections.

4.3.4.1 Fixed Covers and Digester Gas Appurtenances
The existing floating covers will be replaced by fixed covers. The fixed cover design will include the following associated gas control equipment:
 Pressure and vacuum relief valve (with flame arresters and safety selector valve)  Two access covers for operator access and temporary ventilation during confined space entry - Minimum of one 42-inch diameter or larger
 Sludge sampling port
 Pressure relief hatch with vacuum relief function
 Nitrogen purge ports with fame checks
It is recommended to install a foam separator on the gas line to the existing waste gas burner because the WWTF has a history of foaming digesters. The foam separator will be adjacent to the digester building stairway access, as shown on Figure 4-3. It will be supplied by approximately 60 feet of 3-inch-diameter ductile iron pipe (DIP) digester gas piping, which will tie into the existing 3-inch-diameter DIP digester gas pipe between the digester building and the waste gas burner. Three butterfly isolation valves will be installed between the two 3-inch tie-in locations and on the draw and return lines from the foam separator to allow for isolation of the foam separator with continued operation of the waste gas burner.

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Figure 4-3. Digester Gas Foam Separator Location
Table 4-12 presents the cover and gas appurtenance design criteria.

Table 4-12. Cover and Gas Appurtenance Design Criteria
Parameter Value
Digester Cover
Number 2
Type Fixed
Diameter 24 feet
Pressure Relief Hatch
Diameter 24 inches
Maximum Allowed Working Pressure 1 foot
Maximum Allowable Working Vacuum 3-inch water column
Manufacturers Varac, Groth Biogas, Shander, and Jurs
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Parameter Value
Foam Separator
Number 1
Diameter 24 inches
Manufacturer Varec

4.3.4.2 Digester Boiler
The existing boiler is at the end of its useful life, is oversized, and will be replaced. It is not anticipated that a gas conditioning system will be required; furthermore, it is more economical to replace the boiler than to install and maintain a gas conditioning system.

The required boiler design capacity is smaller than the available minimum capacity of boilers that run on digester gas; the typical minimum capacity of a digester gas boiler is 1 million Btu. Smaller boilers typically use natural gas rather than digester gas. Digester gas could be used if a gas conditioning system was installed to clean the gas. However, gas conditioning systems have high capital and maintenance costs and will not be included as part of this project. It may be possible to power a natural gas boiler with digester gas, but this would void the manufacturer’s warranty. The recommendation is to provide an appropriately sized boiler for the digester operation and to use natural gas. If a natural gas boiler is provided, and natural gas is used as the feed source, then all digester gas will be combusted at the waste gas burner.

Table 4-13 provides the boiler design criteria.

Table 4-13. Boiler Design Criteria
Parameter Value
Number 2 (1 duty, 1 standby)
Gas Type Natural gas
Min Capacity, each 450,000 Btu
Horsepower, each 14.40 hp
Manufacturer and Model Torus: WB0500
Hurst: Series 100
Superior: Osage

4.3.4.3 Structural
Current seismic provisions require a freeboard of 3.2 feet for the digesters to preclude designing the fixed covers to contain the sloshing fluid contents. Raising the top of wall elevation at Digester 1 to level with the digester building provides 4.67 of freeboard for a 25-foot operating sidewall fluid depth. Because the digester operation will be modified to have the digesters operating in parallel, maintaining the same fluid elevation in both will require a further wall extension of at least 0.53 foot at Digester 2 to meet the freeboard requirement for the new cover design. A wall extension of 2 feet will be provided to have the top of wall elevations at the same level for both digesters. Modifications to the digester control building built-up roofing will be required where the walls are extended.

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4.3.5 Instrumentation and Controls
New instrumentation will be provided to monitor and control the new process equipment, including the boiler and gas conditioning system, if required. No new process controls, including flow meters and level and pressure instruments are included in the design at this time.

4.3.6 Corrosion
Further condition assessment is required to determine the extent of interior concrete and lining rehabilitation efforts required for the digesters. The concrete interiors of the digesters will likely require enhanced protective measures, especially at the headspace where the wall extensions are constructed.

This is because of the formation of hydrogen sulfide gas in the headspace, which, when combined with moisture, produces sulfuric acid—a substance that significantly deteriorates concrete infrastructure.

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5. Additional Improvements
This section describes the additional discipline-specific improvements required to support the upgrade project.

5.1 Primary Clarifiers
Significant wear was observed on the floor of the primary clarifiers during the conditions assessment conducted in August 2022. Scraper wear tracks have experienced severe corrosion and require replacement.

Operations are currently working to keep the sludge blankets down to limit pressure and damage on flights.

Additionally, while updating the hydraulic calculations to account for realized peak flows, it was identified that the existing structure does not provide for adequate freeboard during peak flow events. The walls of the primary clarifiers will be raised approximately 1 foot to provide adequate freeboard height for peak flow conditions.

5.1.1 Process Description
The existing primary clarifiers are two rectangular clarifiers with chain and flight solids collection mechanisms. Screened and de-gritted influent flow is pumped into the primary clarifier distribution box, and the flow is split into three trains of clarifiers. Scum collected at the surface of the primary clarifiers is transferred to the skimmings collection box by a telescoping valve. The skimmings pump transfers scum to either the headworks or digesters or to the gravity or RDT. Solids collected in the primary clarifiers are transferred to the GT to thicken the solids concentration before the thickened solids are fed to the anaerobic digester. Supernatant of the GT is drained into the plant drain and sent back upstream of the headworks.

5.1.2 Design Criteria
Based on the conditions assessment and the current design conditions, the following are the recommended improvements for the primary clarifier:
 Primary clarifier concrete surfaces exhibit signs of wear and require repair and resurfacing in several locations.
 Replace wood framing walkways with aluminum walkways.  Raise walls approximately 1 foot to provide adequate freeboard.

5.1.3 Process Description
The primary clarifier process will not be modified as part of this project. The rehabilitation only includes replacement or upgrade of failing mechanical systems and structural modifications. The mechanical equipment requiring replacement is shown as follows:
 Replace gear box of north sludge pump.
- Replace clarifier mechanism wear strips, chains, and sprockets.  Provide shelf spare drive for clarifier mechanism.
 Replace buried primary influent valves and provide new T-valve actuator tool.  Replace motor-operated valves and gates in primary effluent flow structure.

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5.1.4 Structural and Architectural Improvements
Surface degradation of the primary clarifier was observed during the 2022 condition assessment.

Cementitious and epoxy repair materials will be used to restore the original concrete sections and surface.

Where required, deteriorated concrete will be removed before repair to ensure the concrete remaining has sufficiently high pH to provide protection against corrosion of the existing reinforcing bars. No rebar will remain exposed following the completion of the improvements.

To provide adequate freeboard height during peak flow events, the walls of the primary clarifiers will be raised approximately 1 foot.

5.2 Grit Removal
The grit classifier equipment and associated piping is nearing the end of its useful life and will be replaced as part of the upgrade project.

5.2.1 Process Description
Two rectangular basins at the end of both primary clarifier basins serve as the grit settling area. Each basin is served by a grit pump that transfers grit to two grit cyclones for removal. Then, the grit is washed and dewatered in the grit classifier, and grit is transferred to a dumpster for removal.

Grit is defined as inorganic particles, such as sand and gravel, and other heavy materials not removed by the coarse screening facility at the headworks. Grit removal protects downstream mechanical equipment and reduces equipment fouling from inorganic particles. Grit accumulation can lead to poor settling in aeration tanks and may reduce biological treatment performance.

The grit classifier and associated piping will be replaced in kind.

5.2.2 Design Criteria
The existing equipment is the WesTech Shafted Grit Screw Classifier. As of January 2021, WesTech discontinued new sales in the headworks equipment line, so an alternate manufacturer is recommended for the replacement equipment. The design criteria of the replacement grit removal equipment will match the existing equipment design. Table 5-1 presents the design criteria. Appendix E provides the equipment cut sheets.

Table 5-1. Grit Removal Design Criteria
Parameter Value
Number of Grit Basins 2
Grit Basin Capacity, each 3.9 MGD
Grit Removal Equipment Model and Manufacturer WEMCO Hydrogritter Grit Cyclone Capacity, each 140 gpm
Cyclone Inlet Pressure 5 psi
Cyclone Flow (Inlet/Underflow) 220/15 gpm
Classifier Horsepower 1/2 hp
Classifier Mesh Capacity 150
Classifier Diameter and Tank Type 12-inch steel
psi = pound(s) per square inch
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5.3 Yard Piping and Valving
Pipe diameter and material information specific to the liquid improvements are in the associated facility section. The digested solids transfer piping will be replaced as part of this project because of the low operating velocities induced by the existing pipe infrastructure and the required transfer flow rate.

Digester gas piping will be replaced as a new digester cover is being added. The material selection is discussed in the following subsections.

5.3.1 Digested Solids Transfer Yard Piping
Digested solids are transferred from the digester building to the dewatering building through an existing 300-foot, 6-inch-diameter diameter pipe. With the new operating scheme, including consistently transferring solids from the digesters to the digested solids storage facility, the existing pipeline results in flow velocities well below the recommended value for fluids, with 3% solids of 2 fps. The existing pipeline will be abandoned in place. A new smaller diameter pipeline will be installed from the digested solids transfer PS to the DS storage facility. Table 5-2 presents the pipeline specification. Figure 5-1 shows the proposed route for the new 4-inch-diameter DS pipe.

Table 5-2. Digested Sludge Transfer
Flow Stream Material Diameter
Approximate
Length
DS (buried) HDPE (DR 7 Class 335) with long
radius bends
4 inches (ID of 3.3 inches) 360 feet
DS (exposed) SST 3 inches 40 feet
HDPE = high-density polyethylene
Figure 5-1. Proposed Digested Sludge Transfer Pipe Route RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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Cleanouts will be provided along the digested solids pipeline length to allow access for periodic maintenance. The cleanout locations are selected based on their location along the pipeline route and accessibility by service truck. These pressure cleanouts can be used to periodically flush the solids pipeline using plant water to prevent blockages. This flush water will be wasted to the digested solids storage basin.

Because adding access water to digested solids is not desired, the cleanout procedure will be performed when the digested solids storage basin is free of SS. The cleanout debris can then be pumped to drain using a sump pump or a vacuum truck. Additionally, the use of pipeline pigs will be considered during final design.

Pig launching is a method of removing blockages in pipelines using a rubber cylinder, which forces the blockage through the pipeline to the discharge location. Pig launching and receiving stations can be provided along the pipeline. However, the inclusion of these will be further analyzed to determine whether there is adequate site spacing for the equipment required for pig launching and retrieval.

5.3.2 Process Valving
The following section identifies the general value selection for use in the project. If the client has different preferences for valve selection, this section will be updated during final design. Table 5-3 presents the general valve selection.

Table 5-3. General Valve Selection by Flow Stream
Valve Type Flow Stream Pipeline Material
Plug Valve DS
WAS
ML
Primary effluent
DIP
Butterfly Valve High pressure air SST
Gate Valve Filter effluent
MBR filtrate
Tertiary effluent
DIP
Gate Valve Process water Brass

5.4 Area Classification
An area classification assessment was completed in accordance with the NFPA standards for the existing and proposed facilities. NFPA 820 is the standard for fire protection in wastewater treatment. It establishes minimum requirements for protection against fire and explosion hazards in wastewater treatment plants, helping engineers classify hazardous spaces, define ventilation requirements, and select proper construction materials to mitigate risks. The area classification designations inform the HVAC design, the electrical components specifications, and equipment location. Appendix H shows the area classification determinations for the existing and proposed facilities.

5.5 Heating, Ventilation, and Air Conditioning
The following are applicable codes and standards for the HVAC and plumbing design for the project:
 2025 CBC (California Code of Regulations Title 24)
 2025 California Mechanical Code
 2025 California Fire Code
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 2025 California Energy Code
 2025 California Building Energy Efficiency Standards
 2025 California Green Building Standards Code
 American Society of Heating, Refrigerating, and Air-Conditioning Engineers - Standard 62.1, Ventilation for Acceptable Indoor Air Quality - Standard 90.1, Energy Standard for Buildings Except Low Rise Residential  Air-Conditioning, Heating, and Refrigeration Institute  Sheet Metal and Air Conditioning Contractor’s Association  HVAC Duct Construction Standards – Metal and Flexible  2024 NFPA 820 Standard for Fire Protection in Wastewater Treatment and Collection Facilities The following standards are based on the 2025 California Energy Commission CEC-400-2002-010-AP, Appendix JA2, Table 2-3 for Crescent City:
 Summer Design: 75°F dry bulb/61°F wet bulb at 0.10% annual frequency of occurrence  Winter Design: 33°F dry bulb at 0.2% annual frequency of occurrence Unless otherwise noted, HVAC design criteria will be as follows:
 Ductwork will be sized for a static pressure drop of 0.8 inch water column (WC) per 100 feet.  Intake louvers will be sized for maximum of 400 feet per minute face velocity based on free area.  Ductwork will be galvanized steel in non-corrosive environments and areas not subject to excess moisture.

Corrosion-resistant ductwork material will be chosen to match the anticipated environmental needs.  Any new HVAC equipment exposed to outdoors will need to be suitable for marine environment.  Where required, ventilation will be sized at 6 or 12 ACH, as dictated by NFPA 820 for de-rating of spaces. Final design will address and include other measures required for declassification.

Table 5-4 and Table 5-5 summarize the HVAC scope and improvements for the individual facilities.

Appendix G provides drawing markups showing the extent of the HVAC replacement work.

Table 5-4. HVAC – New Facilities
Facility Extent of Scope Notes
MBR Building
Electrical Room
Indoor design criteria will be 85°F for cooling and
50°F for heating. Packaged DX heat pump will
provide heating, cooling, and ventilation.

Installation of new MCCs is
anticipated.

Dewatering
Electrical Room
Indoor design criteria will be 85°F for cooling and
50°F for heating. Packaged DX heat pump will
provide heating, cooling, and ventilation.

Installation of new MCCs is
anticipated.

Pump Gallery Ventilate and cool with wall-mounted louvers with motorized dampers and roof-mounted fans with
backdraft dampers.

Heating will be provided with wall-hung electric unit
heaters. The intake louvers will be sized for 300 feet
per minute based on the free area of the louver.

The indoor design criteria will
be 10°F above ambient for
cooling and 55°F for heating.

Ventilation minimum will be
sized in accordance with
NFPA 820 for derating
(12 ACH)
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Facility Extent of Scope Notes
Solid Storage
Pump Gallery
Ventilate and cool with wall-mounted louvers with
motorized dampers and roof-mounted fans with
backdraft dampers.

Heating will be provided with wall-hung electric unit
heaters. The intake louvers will be sized for 300 feet
per minute based on the free area of the louver.

The indoor design criteria will
be 10°F above ambient for
cooling and 55°F for heating
DX = direct exchange
MCC = motor control center
Table 5-5. HVAC Improvements – Existing Facilities
Facility Extent of Improvements Reasoning
Digester Building Replace all HVAC equipment in kind. Past useful life MBR Building –
Chemical Room
Replace fan F-4124 and associated
ductwork with new 316 stainlesssteel ductwork.

Ducts and fan showing signs of
corrosion and need for replacement
Administration
Building
Replace all HVAC equipment in kind. Past useful life
Dewatering Building Replace all HVAC equipment in kind
(fans, ductwork).

Past useful life; need to guarantee
complying with standard NFPA 820
(6 ACH of ventilation)

5.6 Supervisory Control and Data Acquisition Improvements The existing control system at the WWTF consists of a combination of vendor-supplied package system controllers, balance-of-plant controllers, and three standalone human-machine interface (HMI) workstations/servers. The scope of SCADA improvements for this project is focused specifically on process areas undergoing upgrades, with enhancements limited to control system components necessary to support those improvements.

The following key process areas are anticipated to impact the existing control system and will require integration or modification to the SCADA components:
 Primary clarifiers
 Grit removal system
 MBRs
 Cloth filters
 WAS storage and pumping
 GTs
 DS pumping

5.6.1 Equipment and Tag Numbering Convention
The WWTF currently uses a documented tag naming convention for equipment and instrumentation.

However, this schema was not made available to Jacobs before the development of this preliminary design report. Once obtained, Jacobs will review and validate the schema to ensure consistency with existing plant standards. Before assigning tags to new equipment and instrumentation, Jacobs will confirm the availability of unused tag numbers to avoid duplication. All new tags will adhere to the established naming convention and will be uniquely assigned to support clear identification and integration within the upgraded control system.

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5.7 Communication Block Diagram
The existing facility-wide communication ring is expected to remain largely intact throughout the proposed modifications. However, additional control panels may be required to support new input/output (I/O) points in areas where existing panels lack sufficient capacity. It is not anticipated that new programmable logic controller (PLC) processors will be necessary, except for PLCs required by the proposed equipment manufacturers, including filter equipment and the MBR facility. New panels will be configured as remote I/O panels to minimize costs associated with procuring additional processors.

Current assessments indicate the existing PLC processors are adequately sized to handle both current operational demands and the anticipated improvements. All new interbuilding Ethernet communication will use fiber optic cabling to ensure high-speed and reliable data transmission. Within buildings, new communication links will be established using copper-based cabling where appropriate.

5.7.1.1 Programmable Logic Controller Standards
The existing WWTF is standardized on Allen-Bradley ControlLogix PLCs for all area control panels.

This platform has been in use for many years and is well-established across the facility. However, some components may be outdated or approaching obsolescence, particularly if they have not been upgraded in recent years. For example, the ControlLogix L5x series processors are discontinued, no longer manufactured, and commercially unavailable. At the time of this report, a formal condition assessment of the control system PLCs had not been completed by an instrumentation and control engineer, and operations and maintenance documentation for the area PLCs had not been provided. As the design progresses, any high-risk or obsolete PLC components identified will be reviewed with project stakeholders to determine appropriate alternatives or upgrade strategies.

To maintain consistency and ensure seamless integration with the existing SCADA system, all packaged system suppliers will be required to provide Allen-Bradley PLCs—specifically ControlLogix, CompactLogix, or MicroLogix platforms—provided they are compatible with the existing area controllers. This requirement supports long-term maintainability and reduces integration complexity across the facility.

The MBR system, based on available as-built documentation, currently uses ControlNet for communication between the MCP and the LCPs. Because ControlNet support is being phased out in newer Allen-Bradley PLC models, all existing ControlNet infrastructure will be decommissioned and replaced with Ethernet/Internet Protocol (EtherNetIP) communication. All new communication associated with the MBR system will also use EtherNetIP and interface with the existing MCP. Additionally, any obsolete PLC communication components within the MCP and LCPs will be upgraded to ensure long-term reliability and supportability. These upgrades will be defined as part of the membrane supplier’s scope of work.

The cloth filter systems, also provided by a packaged system manufacturer, will include dedicated Allen-Bradley PLCs that will be integrated into the existing plant network. This approach ensures compatibility with the current SCADA system and supports the facility’s standardized control architecture.

Each cloth filter PLC will be configured to communicate effectively with the broader control system, maintaining operational consistency and simplifying future maintenance.

Control panel designs will include an uninterruptible power supply for all critical control components, including PLC power supplies, 24 volts direct current power supplies, instrumentation power from the panel, and other critical control components. Each device will be powered with a dedicated overcurrent protective device to isolate faults while maintaining power to the other critical components.

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5.7.1.2 Human-Machine Interface Standards Hardware and Software The facility currently uses three Windows 10-based desktop computers as the primary HMI. These systems serve as the central interface for monitoring and controlling plant operations. With Microsoft’s announcement of the end of support for Windows 10 in October 2025, the City has initiated plans to upgrade or replace these computers with Windows 11-compatible systems. As part of this upgrade, the Rockwell Automation FactoryTalk View Site Edition software will also be updated to the latest available version to ensure continued compatibility and support. These upgrades are expected to be completed before the start of construction and will not be included in the contractor’s scope of work for this project.

The design will incorporate provisions to support all new process modifications planned for the facility.

This includes enhancements to the control system and reporting capabilities necessary to meet updated regulatory requirements. In particular, the upgraded system will include functionality to support expanded reporting needs associated with NPDES compliance, ensuring the facility can maintain accurate and timely environmental reporting in alignment with permit obligations.

To ensure the upgraded control system meets the operational needs of the facility, the design will include collaborative screen development and programming workshops. These workshops will be conducted by the contractor, with active guidance from the engineering team and direct feedback from City staff.

The purpose of these sessions is to develop and refine HMI screens, control logic, and reporting tools in alignment with the facility’s workflows, operational preferences, and regulatory requirements.

This collaborative approach will help ensure the final system is intuitive, functional, and tailored to support both routine operations and compliance-related tasks, including those associated with NPDES reporting.

5.7.2 Preferred Instrumentation
The City provided a short list of preferred instrumentation manufacturers, which will be referenced in the design documentation. At a minimum, these preferred vendors will be named as the basis of design and, in some cases, may be specified as sole-source providers if desired. Given the relatively low volume of instrumentation required for this project, sole sourcing is not expected to significantly impact bid competitiveness or pricing. The following section outlines the types of instrumentation anticipated for the project, along with the City’s preferred manufacturers, which are provided as follows:
 Ultrasonic Level Transmitters – Siemens
 Magnetic Flow Meter – Emerson Rosemount
 Pressure Transmitters – Emerson Rosemount
 Analytical Instruments – Hach

5.8 Electrical Improvements
Two new MCCs are required to power the proposed new equipment. Figure 5-2 shows the electrical one-line diagram for the proposed upgrade project. Loading for MCC-4002 will increase, requiring the feeder breaker in MCC-4002 feeding MCC-4002A to be upsized to 400 amperes (A). The cable connecting MCC-4002A and P4002AA will also need to increase to size MCC-500 cable. Appendix H includes the half-size drawing sheets for the recommended electrical improvements.

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Figure 5-2. Electrical One-Line Diagram

5.8.1 Motor Control Center for new Membrane Bioreactor Facility The MBR facility equipment can be run by a new MCC-4002B in the current MBR Electrical Room 40-03.

The electrical bus and SCADA net trunk connections of existing MCC-4002A would be extended to the new six section line up. Figure 5-3 shows the proposed location and MCC elevation.

Figure 5-3. Motor Control Center 4002B Plan and Elevation RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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Table 5-6 presents the equipment associated with MCC-4002B.

Table 5-6. Motor Control Center 4002B
Equipment Name Quantity
Horsepower,
each Control Type
Facility
Location
ML Pumps 3, 4, and 5 3 20 Adjustable speed MBR Train 2
Filtrate Pumps 3, 4, and 5 3 7.5 Adjustable speed MBR building Aeration Tank Transfer Pump 1 5 Constant speed MBR Train 2 Fine Screen 2 1 5 Constant speed MBR Train 2
Recycle Pump 2 1 7.5 Adjustable speed MBR Train 2
Anoxic Mixer 2 1 5 Constant speed MBR Train 2
Air Scour Blower 3 1 32 Adjustable speed MBR building
The MBR building additions are approximately 145 hp in base connected load. If all run at full load, the expected current would be 180 A in accordance with National Electrical Code (NEC) Table 430-150.

The existing feed from MCC-4002 to MCC-4002A is a 400-A breaker set at 250-A trip. Loading per drawing for MCC-4002A is approximately 170 A. The new MCC-4002B loads will not be run at full load simultaneously, and the expected amperage is expected near 150 A or less.

The upstream feed from MCC-4002 is 3#250MCM, rated for approximately 250 A. The feed would need to be upgraded to 3#350 at a minimum. The existing 3-inch galvanized rigid steel will accept up to 5#350MCM or 4#500 cables. Conduit run will need to be assessed for routing and pull constraints.

5.8.2 Motor Control Center for Attached Growth Facility, Filter Facility, and Waste Activated Sludge and Digested Sludge Storage Equipment There is adequate space and power to support an additional small MCC in the dewatering building to support new operating loads for the attached growth facility, the filter facility, and the WAS and DS storage equipment. Space near an existing wall appears available to install a new, one section MCC-7201A.

Figure 5-4 shows the elevation view of the proposed MCC-7201A. This MCC will be in the dewatering building electrical room. The existing MCC-7201 will have available bucket sections because of the removal of RBCs 4010 through 4120 and Blower BLO-4130. MCC appears to be a GE Evolution series and is still supported by the acquiring company ABB. Spacing for the replacement buckets will need to be verified with the ABB vendor. Overall, the connected load to MCC-7201 is increased by approximately 40 A.

Figure 5-4. Motor Control Centers 7201A Elevation
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Table 5-7 presents the equipment associated with MCC-7201 and MCC-7201A. There will be 2 to 10 hp constant speed DS pumps added to this existing MCC. Loading for the two pumps at full load adds 28 A to the existing 308 A.

Table 5-7. Motor Control Centers 7201 and 7201A
Equipment Name Quantity
Horsepower,
each Control Type Facility Location
MCC-7201
SS Transfer Pumps 1 and 2 2 10 Adjustable speed Pump gallery MCC-7201A
Aeration Blower, Attached
Growth Trains 1 and 2
2 50 Adjustable speed Adjacent to
dewatering building
Disk Filter Trains 1 and 2 2 1 Constant speed Cloth disk filters Filter Backwash Pumps 1 and 2 2 2 Constant speed Cloth disk filters Mixing Pumps 1 and 2 2 15 Constant speed Pump gallery
Jet Aerators 1 and 2 2 15 Constant speed WAS storage basin The dewatering building additions are approximately 200 hp in base connected load. If all run at full load, the expected current would be 240 A in accordance with NEC Table 430-150. The existing feed from MCC-7201 to MCC-7201A is an 800-A breaker set at 800-A trip. Loading per drawing for MCC-7201 is approximately 308A+28A (new DS pumps). The new MCC-7201A loads will not be run at full load simultaneously, and the expected amperage is expected near 200 A or less.

The upstream feed from MCC-7201 is 9#500MCM, rated for approximately 1,140 A. The feed would not need to be upgraded.

5.8.3 Outstanding Issues
For MCC-4002B, coordination of breaker settings will need to be reviewed, along with an updated arc flash study, to ensure proper labeling on existing and new MCC components.

Heat loading because of additional adjustable frequency controllers (AFCs) is approximated at 1.65 tons = 19,855 British thermal units per hour (Btu/hour) when all units run at full load. Present HVAC for Electrical Room 40-03 needs to be evaluated for sufficient cooling.

For MCC-7201A, coordination of breaker settings will need to be reviewed, along with an updated arc flash study, to ensure proper labeling on existing and new MCC components.

Heat loading because of additional AFCs is approximated at 2.3 tons = 27,500 Btu/hour when all units run at full load. Present HVAC for the dewatering floor area needs to be evaluated for sufficient cooling.

Any electrical equipment within classified areas will need to be explosion proof. This includes all motors (new or existing to be upgraded), disconnect switches, conduits, and fittings.

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5.9 Odor Control
Odors produce the most direct impact that a WWTF has on its surrounding environment. Odor management at the Crescent City WWTF is critical to establishing its reputation as a good neighbor to the surrounding community.

The North Coast Unified Air Quality Management District (NCUAQMD) regulates odors for the City.

Odors are classified as an “air contaminant” under district rules, and facilities can be required to obtain permits and comply with emission limits to prevent objectionable odors that could affect a substantial number of people.

Odor is treated as a nuisance with regulations stating it is never legal to impact neighbors with odors (qualitative and not quantitative). Facilities must operate in a manner that does not cause a nuisance.

The district has the authority to enforce rules that limit or control emissions, including odors.

5.9.1 Odor Source Descriptions
The existing plant does not currently exhibit offsite odor impacts resulting in odor complaints.

Furthermore, there are no regulatory requirements or air permit requirements dictating emissions limits because the plant is not expanding capacity, and therefore, emissions are not expected to increase.

Table 5-8 and Table 5-9 describe the plant process odor sources.

Table 5-8. Liquids Processes Odor Sources
Process Area Odor Source Description
New Odor
Control Measures
Required?
Course Screen and
Dumpster
This source is typically considered to generate moderate nuisance odors. However, while this source is an open
source, because the sewage is believed to be “fresh,” odors have historically been mild, and there is a significant buffer between the plant boundary and the nearest odor receptor, odor control is not considered to be necessary. As such, no odor control is provided for this source at this time. Note that primary/preliminary sources are not currently covered and do not result in any offsite odor complaints
No.

Influent Pumping This source is enclosed such that any emissions are limited.

Therefore, odor control is not considered necessary for this source at this time.

No.

Aerated Grit and
Grease Removal
plus Dumpster
These sources are typically considered to generate
moderate nuisance odors. However, while these sources are open sources, their distance from the plant fence line
coupled with “fresh” wastewater characteristics allows these sources to remain uncontrolled. As such, no odor control is provided for these sources at this time.

No.

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Process Area Odor Source Description
New Odor
Control Measures
Required?
Open Primaries This large open area source is typically considered to generate moderate nuisance odors. However, because of
“fresh” wastewater characteristics, this large open source has historically not generated significant nuisance odors and is not considered to be a key offsite odor impactor.

Therefore, no covering or odor control treatment is
considered necessary at this time. Note that primary/
preliminary sources are not currently covered and do not result in any offsite odor complaints
No.

Screen Trains,
MBR’s, ML PS,
Attached Growth
Treatment Facility
Because these processes are downstream of primary
sedimentation, the potential for nuisance odor emissions is significantly reduced. Furthermore, the type of odors
expected are primarily earthy-musty and therefore are less offensive. As such, these sources do not warrant odor
control at this time.

No.

Table 5-9. Solids Process Odor Sources
Process Area Odor Source Description
New Odor
Control Measures
Required?
Primary Sludge
Transfer PS
This facility is a modification to an existing pump gallery in the digester building. This PS is covered, and therefore, emissions are expected to be appropriately suppressed. Therefore, no odor control is considered for this source at this time.

No.

Primary Sludge
GT
This process will be fully rehabilitated with new mechanism, coating systems, and walkway. In addition, the tank will be provided with FRP covers that are not airtight, allowing some fugitive odor emissions between walkway and covers. However, the covers are expected to suppress approximately 80% to 90% of the emissions. Therefore, no additional odor control is deemed necessary at this time.

No.

WAS Storage The western secondary clarifier will be retrofitted to provide an open-air WAS storage with aeration. Because WAS is typically not a significant odor emitter, with odor characteristics more earthy-musty, which is less offensive, no odor control is considered necessary for this source at this time.

No.

WAS Drum
Thickener
Similar to WAS storage, because WAS is typically not a
significant odor emitter, with odor characteristics more earthymusty, this process is not required to be odor controlled at this time.

No.

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Process Area Odor Source Description
New Odor
Control Measures
Required?
SS PS The SS PS will be in the modified secondary clarifier and will be covered/enclosed with louver for passive ventilation. Expected odor emissions from this source are predicted to be moderate.

However, with cover and passive ventilation, any odor plume is expected to be small and therefore a low risk for offsite odor impacts. As such, no odor control is considered for this source at this time.

No.

Anaerobic
Digesters
This process is fully enclosed, and therefore, emissions are expected to be nil.

No.

DS Storage The DS storage will be in the modified secondary clarifier and will be covered/enclosed with louver for passive ventilation.

Expected odor emissions from this source are predicted to be moderate. However, with cover and passive ventilation, any odor plume is expected to be small and therefore a low risk for offsite odor impacts. As such, no odor control is considered for this source at this time.

No.

Dewatering BFP The dewatering BFP is considered a moderate odor source because sludge is agitated, and offgassing is expected to result in nuisance odors characterized by hydrogen sulfide and various reduced sulfur compounds. Currently, an odor control system (ORT-7291) serves this source. ORT-7291 is a dry media
adsorption system designed to remove odors typical of
biosolids. This existing system is believed to be adequately treating odors from this source. Therefore, no replacement is being considered at this time.

No.

5.9.2 Odor Control System Sizing
The existing ORT-7291 is sized to contain, capture, and treat odors from the dewatering BFP area.

Ventilation rates for sizing odor control systems typically comply with NFPA 820 and Jacobs engineering design practice for similar type facilities. In general, ventilation rates should meet the following objectives:
 Provide adequate ventilation to protect maintenance personnel within occupied spaces in accordance with NFPA 820, “Fire Protection in Wastewater Treatment and Collection Facilities,” latest edition.  Maintain a minimum negative pressure of 0.1-inch WC within wastewater holding tanks to contain odors under the following conditions:
- Dynamic liquid level changes
- Estimated crack openings in storage tank covers treated as sharp-edged orifices  When a single access cover is removed, maintain sufficient velocities across the opening to prevent fugitive odors.
 Provide adequate turnover rate and air scavenging within storage tanks to reduce corrosion resulting from hydrogen sulfide pockets.

Note that ORT-7291 capacity can likely be adjusted by speeding up the fan in case ventilation rates are deemed inadequate.

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5.9.3 Triggers Prompting Future Re-Evaluation of Odor Control The following are considered triggers that would prompt future re-evaluation of odor control requirements at the plant:
 Encroachment of sensitive receptors, such as residential developments closer to plant boundary, which increase offsite odor sensitivity
 Changes in plant processes resulting in stronger odor emissions or more offensive odors  Increase in odor complaints from offsite receptors
 Changes in air quality regulatory requirements resulting in more stringent odor or toxic air contaminant limits
 Increase in plant capacity in the future that could trigger NCUAQMD permitting requirements Recommended next steps to stay ahead of odor issues include the following:
 Consider an ongoing odor monitoring program, which could include a weekly odor tour along the plant fence line to ensure fugitive odors are not present.
 Consider annual odor sampling of key sources at the plant and input into an odor air dispersion model for predicting offsite odor impacts.

Some recommended controls for preventing or limiting offsite odor impacts include the following:
 Maintain good housekeeping practices by hosing down idle wastewater or sludge storage tanks, removing any residuals or spills in a timely manner, and avoiding plant upsets.

5.10 Corrosion Control and Mitigation
The corrosion control and mitigation design will be based on the following codes and regulations:
 American Concrete Institute (ACI)
 ASTM international (ASTM)
 American Water Works Association (AWWA)
 Association for Materials Protection and Performance
 Ductile Iron Pipe Research Association
 U.S. Environmental Protection Agency (EPA)
 International Standard Organization (ISO)
 National Electrical Manufacturers Association (NEMA)
 The Society for Protective Coatings
 Underwriters Laboratories, Inc.

The aforementioned organizations have established standards to serve as guides, ensuring the quality and reliability of components and systems. These standards also govern nomenclature and define parameters for configuration and construction. The corrosion control design approach for this project can be divided into the following two categories:
 Identifying the corrosivity of the environment in relation to the proposed facility equipment and structures, which involves the following:
- Conducting field testing to ascertain the corrosivity of the environment on interacting with the process structures and construction materials
- Analyzing historical corrosion data/studies to determine the intended corrosion control approach RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
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 Developing a comprehensive corrosion mitigation strategy that involves addressing a variety of environments that pose a potential threat to construction materials. This strategy covers the following underlying factors:
- Atmospheric Conditions:
 Accounting for various other conditions that may contribute to corrosion risks  Identifying specific challenges unique to the environment and developing targeted mitigation measures
- Buried Environments:
 Proposing measures to protect materials used in buried structures  Proposing factors such as soil composition and moisture levels - Submerged Conditions:
 Proposing a cost-effective solution to counter corrosion in materials exposed to submerged environments
 Ascertaining the impact of water chemistry and depth on corrosion susceptibility

5.10.1 Atmospheric Conditions
Atmospheric conditions are expected to be highly corrosive because of the WWTF’s proximity to the coast.

Atmospheric corrosivity will be determined in accordance with ISO 9223 or ISO 12944-2. These corrosive conditions will require that permanent facilities be properly protected for long-term service using corrosion-resistant materials and durable protective coatings where appropriate.

In addition, it is essential that materials and equipment are properly stored and protected during the construction period. Instrumentation, controls, and electrical and mechanical equipment are components that are most susceptible to damage by corrosion during the construction period.

The ISO Corrosivity Classification method, which is contained in ISO 9223 “Corrosion of Metals and Alloys,” is divided into six environmental severity classification, as outlined in Table 5-10. Table 5-11 provides the corrosion rates for the first year of exposure for different corrosivity categories.

Table 5-10. Atmospheric Corrosion Classification
Category Corrosivity
C1 Very low
C2 Low
C3 Medium
C4 High
C5 Very high
CX Extreme
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Table 5-11. Corrosion Rates, for the First Year of Exposure for the Different Corrosivity Categories Corrosivity
Category[a]
Corrosion rates of Metals
rcorr
Unit Carbon Steel Zinc Copper Aluminum[b]
C1 g/( m2·a)
μm/a
rcorr ≤ 10.0
rcorr ≤ 1.3
rcorr ≤ 0.7
rcorr ≤ 0.1
rcorr ≤ 0.9
rcorr ≤ 0.1
negligible
—
C2 g/( m2·a)
μm/a

10.0 <rcorr ≤ 200

1.3 < rcorr ≤ 25.0

0.7 < rcorr ≤ 5

0.1 < rcorr ≤ 0.7

0.9 < rcorr≤ 5.0

0.1 < rcorr ≤ 0.6
rcorr ≤ 0.6
—
C3 g/( m2·a)
μm/a
200 < rcorr ≤ 400

25.0 < rcorr ≤ 50.0

5.0 < rcorr ≤ 15.0

0.7 < rcorr ≤ 2.1

5.0 < rcorr ≤ 12.0

0.6 < rcorr ≤ 1.3

0.6 < rcorr ≤ 2.0
—
C4 g/( m2·a)
μm/a
400.0 < rcorr ≤ 650.0

50.0 < rcorr ≤ 80.0

1.5 < rcorr ≤ 30.0 2.1
< rcorr ≤ 4.2

12.0 < rcorr ≤ 25.0

1.3 < rcorr ≤ 2.8

2.0 < rcorr ≤ 5.0
—
C5 g/( m2·a)
μm/a
650.0 < rcorr ≤ 1500.0

80.0 < rcorr ≤ 1200.0

30.0 < rcorr ≤ 60.0 25.0 < rcorr ≤ 50.0 5.0 < rcorr ≤ 10.0

4.2 < rcorr ≤ 8.4 2.8 < rcorr ≤ 5.6 —
CX g/( m2·a)
μm/a
1 500.0 < rcorr≤ 5500.0
200.0 < rcorr ≤ 700.0

60.0 < rcorr ≤ 180.0

8.4 < rcorr 25.0

50.0 < rcorr ≤ 90.0

5.6 < rcorr ≤10.0
rcorr > 10.0 —
Source: ISO 9223 2012
[a] The classification criterion is based on the methods of determination of corrosion rates of standard specimens for the evaluation of corrosivity (refer to ISO 9226).
[b] Aluminum experiences uniform and localized corrosion. The corrosion rates shown in this table are calculated as uniform corrosion. Maximum pit depth or number of pits can be a better indicator of potential damage. It depends on the final application.

Uniform corrosion and localized corrosion cannot be evaluated after the first year of exposure because of passivation effects and decreasing corrosion rates.
g/(m2·a) = gram(s) per square meter per year
μm/a = micrometer(s) per year
rcorr = corrosion rate

5.10.1.1 Design Recommendations
Recommendations for ferrous metals are as follows:
 Protect with an epoxy barrier coating; add UV-resistant topcoat to minimize chalking of epoxy coatings exposed to sunlight.
 Polymer-based materials (that is, plastic, non‐metallic): Paint with a UV barrier (spray‐applied coating) or provide material with resin that is UV stabilized (such as gel-coated FRP).  Stainless steel: Protective coating is not required except for color‐coding purposes.  Copper‐based materials: Protective coating is not required except for color‐coding purposes; avoid where traces of hydrogen sulfide are present.
 Concrete and masonry: Painting is not required except for architectural purposes.  Anchor bolts: Use stainless steel for anchor bolts; use stainless steel in high wash-down areas.  Concrete embedded items (frames, grating): Use stainless steel; use hot-dip galvanized steel for indoor, dry exposures only.
 Covers and floor plates: Use stainless steel.

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Recommendations for gratings, railings, and covers are as follows:
 Use anodized aluminum.
 Use stainless steel or fiberglass where exposed to continuously wet environment; fiberglass requires a UV barrier or integral gel coat.

Recommendations for the electrical system, include the following:
 Panels and Fixtures: Align with the pertinent NEMA classification; panels and fixtures commonly use the standard materials and finishes provided by the manufacturer. Optimal choices for locations with corrosive conditions include 316 SST NEMA enclosure Types 3, 4, and 6. In scenarios involving locally corrosive conditions, such as areas frequently subjected to washdowns, the use of watertight enclosures is also imperative.
 Conduits: Preferably, buried electrical conduits should be made of PVC. However, when metallic raceways are necessary or when exposed to outdoor elements or indoor wet conditions, PVC-coated galvanized steel or aluminum metal becomes a viable alternative. This material is also suitable for concrete floor and slab penetrations, especially during transitions from buried PVC conduit.

In scenarios where dry conditions persist indoors, galvanized steel can be used for exposed conduits.

Furthermore, PVC-coated conduits are recommended in areas with locally corrosive conditions.  Grounding: Copper grounding materials may require supplemental corrosion protection depending on the corrosivity of the soil.

Other recommendations are as follows:
 Ladders: Use aluminum or stainless steel.
 Architectural components and louvers: Use fluoropolymer (Kynar)-coated aluminum; aluminum and painted steel are also acceptable.
 Stairs: Use aluminum if possible; hot-dip galvanized steel is acceptable in areas where trace hydrogen sulfide is not present.

5.10.2 Immersion Exposure
The generation of hydrogen sulfide may occur in significant amounts as wastewater travels through the collection and conveyance systems. This phenomenon typically results from the breakdown of organic matter and underscores the need for careful monitoring. Currently, the specific chloride content of the wastewater has yet to be assessed, but preliminary assumptions suggest it will exceed 200 ppm, indicating a considerable presence. Furthermore, sulfate concentrations will play a crucial role in determining the exposure class as defined by the ACI. While sulfate levels are expected to be relatively low, their exact impact will need to be evaluated to ensure appropriate materials and construction practices are employed to mitigate any potential exposure risks.

5.10.2.1 Design Recommendations
Following are immersion exposure design recommendations for the project:
 Ferrous metals: Provide high‐performance protective coatings.  Stainless steel: Use Type 316/316L.
 Aluminum: Not recommended for immersion service.
 Pipe: Use stainless steel, PVC, chlorinated PVC, HDPE, or FRP without protective coating or lining.

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 Concrete: Provide protective lining for all concrete above the water line in concrete hydraulic structures exposed to hydrogen sulfide
 Anchor bolts and fasteners: Use Type 316 stainless steel.  Frames (for grating, covers, slide gates, and similar): Use stainless steel.  Slide gates, weir gates, and weirs: Use stainless steel or FRP.

5.10.3 Buried Exposure
A geotechnical investigation of the soil within the project site is required to be conducted to ascertain the corrosivity of the soil for buried ferrous metals. The laboratory soil analysis will include the moisture content, pH, electrical conductivity (converted to resistivity), chloride content, sulfate content, oxidation-reduction potential (commonly termed “redox potential” or “redox”), and presence of sulfides; all these are factors that can relate to corrosion of buried pipe materials.

Moisture content is a measure of the percentage by mass of water contained within the soil and is indicative of natural moisture conditions present in the site soil. This is helpful to understand how likely laboratory-tested conductivity and resistivity values will be present in the field. Conductivity and resistivity are often tested on saturated samples, so moisture content creates a more realistic appraisal of site soil conditions. However, this is limited to the time of year that the soil samples are collected and should be considered in concert with yearly weather conditions.

The pH is a measure of the soil’s acidity and is determined by the concentration of hydrogen ion. Acidic pH values (below 7) in soils have the potential for deterioration or softening of cement mortar because of the acid-base reaction with the alkaline portland cement in these materials. Soils with pH values less than 5 can be detrimental to cement mortar and concrete. Progressively lower values are increasingly aggressive to ferrous metal pipe, and at pH values below 4, severe conditions exist.

Resistivity is a measure of the electrical conductivity of the soil, the value of which is obtained from the inverse of the measured conductivity value. It is determined by factors including the type of soil, mineral content, and moisture content. Low resistivity is correlated with a high potential for corrosion of ferrous metals. Resistivity alone is not a factor in the deterioration of concrete pipe because it is nonmetallic, and the metallic reinforcement within the concrete is protected by a passive film imparted by the highly alkaline concrete. However, it is expected that galvanic corrosion rates will increase in areas with lower resistivities, and any ferrous metal pipes directly connected to concrete pipes would be at risk of increased corrosion rates. Table 5-12 details the correlation between soil resistivity and corrosivity levels of soils at different soil types and resistivity boundaries.

Table 5-12. Soil Resistivity Correlation with Corrosivity Levels Soil Resistivity (Ω-cm) Soil Type Moisture Corrosivity
<500 Muskeg/sloughs/free water Always wet Very corrosive 500 to 2,000 Loamy/clay Mainly wet Corrosive
2,000 to 10,000 Gravels, sandy Mainly dry Moderately corrosive 10,000 to 20,000 Arid, sandy, gravel Always dry Mildly corrosive >50,000 Gravels, sandy Always dry Essentially noncorrosive Sources: Roberge 2008; CAPP 2018
Ω-cm = ohm-centimeter(s)
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Chloride content is a measure of the amount of chloride ions present in the soil, and higher values correlate with higher corrosion rates of steel and metallic reinforcement in concrete. The concrete cover over the metallic reinforcement provides a highly alkaline environment and maintains a passive film on the metal. With higher chloride content, the passive film can be more easily broken down by chloride penetration to the underlying metal, resulting in increased corrosion rates. For soils with presence of chlorides, supplementary cementitious material additions, such as fly ash, slag cement, and silica fume are recommended. Alterations in the concrete mix properties, including maximum water to cement ratio, minimum strength, maximum chloride ion, amount of cover, and corrosion inhibitor additions can also be made to slow the diffusion of chloride ions through the concrete to limit corrosion on the underlying metal. The American Concrete Pressure Pipe Association recommends that when chloride levels exceed 400 milligrams per kilogram (mg/kg) and soil resistivity is below 1,500 Ω-cm, protective measures should be implemented. Protective measures recommended by American Concrete Pressure Pipe Association include a moisture barrier on exterior concrete surfaces, silica fume at 8% to 10% of cement weight or a corrosion inhibitor in the concrete mortar, and cathodic protection.

Sulfate content is a measure of the amount of sulfate ions present in the soil, and higher values correlate with higher corrosion rates of steel, concrete, and cement mortar. Sulfates can be particularly detrimental to concrete materials through chemical and physical attacks that may occur synergistically.

Sulfates can chemically react with compounds in concrete, which can lead to softening or physical expansion and cracking of the concrete. For soils with significant levels of sulfates, the concrete mix should be altered to limit the ability for sulfate ions to diffuse. Common alterations include lowering the water to cement ratio, decreasing the tricalcium-aluminate content, and adding pozzolans and slag.

Documentation from the ACI recommends that sulfate concentrations of 200 mg/kg are significant and that cementitious materials have special requirements for sulfate resistance starting at that level; concentrations above 2,000 mg/kg are of even greater concern. Sulfates can also affect concrete and ferrous metals by allowing the growth of sulfate-reducing bacteria, which reduces the sulfates to sulfides.

The sulfide-based waste products of these bacteria are expected to be corrosive to ferrous metals and cementitious materials.

Redox is a measure of the degree of aeration of the soil, and lower values are typically correlated with anaerobic soil conditions that can support sulfate-reducing bacteria, which are expected to be corrosive to ferrous metals and cementitious materials. Redox values less than 300 millivolts (mV) are of note when sulfides are also present, and values less than 100 mV are indicative of anaerobic soil conditions.

Measuring the presence of sulfides is a qualitative method of evaluating the presence of sulfate-reducing bacteria and is typically evaluated in concert with redox potential. When sulfides are present and redox values indicate anaerobic soil conditions, it is indicative that sulfate-reducing bacteria exist, and cementitious materials and ferrous metals are at greater risk of corrosion. Table 5-13 lists soil test parameters required by a laboratory on geotechnical analysis of the soil.

Table 5-13. Corrosion Parameters
Parameter Classifications Based on the Following Guideline Unit of
Measurement
Soil Resistivity ASTM G187, ASTM G57, BS1377 Part 3:1990 or equivalent Ω-cm Moisture Content ASTM D2216 – 92 or BS1377 Part 2:1990 or equivalent % pH Measurements ASTM D4972 – 13 or BS1377 Part 3:1990 or equivalent N/A Chloride Ion
Concentration
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Parameter Classifications Based on the Following Guideline Unit of
Measurement
Sulfate Ion
Concentration
Applicable ASTM or BS1377 Part 3:1990 or equivalent ppm or mg/kg Sulfide Ion
Concentration
Applicable ASTM or EPA Method 9034 or EPA Method
9215 or AWWA C105 or equivalent
ppm or %
Electrical Conductivity BS ISO 11265 or equivalent S/m
Redox Potential ASTM G200, BS1377 Part 3:1990, or equivalent mV S/m = siemen(s) per meter
Table 5-14. Effects Or Environmental Factors on Corrosion Of Steel In Soil Environmental Factor
Overall Corrosion Rate
(mm/year) Maximum Pitting Rate (mm/year)[a]
Maximum Minimum Average Maximum Minimum Average
Resistivity (Ω-cm)
<1,000 0.063 0.018 0.033 0.31 0.6 0.20
1,000 to 5,000 0.058 0.006 0.017 >0.45[b] 0.05 0.14
5,000 to 12,000 0.033 0.005 0.018 0.23 0.06 0.14
>12,000 0.036 0.003 0.014 0.26 0.03 0.6
Drainage
Very Poor 0.058 0.038 0.046 >0.45[b] 0.16 0.28
Poor 0.037 0.010 0.024 0.23 0.05 0.14
Fair 0.063 0.018 0.022 0.31 0.08 0.16
Good 0.022 0.003 0.010 0.18 0.03 0.6
Porosity (Air Pore Space Percentage)
<5 0.033 0.010 0.021 >0.45[b] 0.16 0.28
5 to 10 0.063 0.009 0.024 0.23 0.05 0.14
10 to 20 0.037 0.006 0.017 0.31 0.08 0.16
20 to 30 0.058 0.012 0.024 >0.45[b] 0.03 0.6
>30 0.038 0.004 0.013 0.23 0.03 0.09
Source: Revie 2000
[a] Original data are based on National Bureau of Standards field test on open-hearth steel for 12 years at 44 locations in the U.S. [b] Perforated
mm/year = millimeter(s) per year

5.10.3.1 Design Recommendations
Other design recommendations are detailed as follows.

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5.10.3.1.1 Steel Pipe and Appurtenances
Employ high-quality protective coatings, such as specialized epoxy or polyurethane coatings, which provide a barrier against moisture and corrosive agents. Additionally, implement cathodic protection systems, including sacrificial anodes or impressed current systems, to further mitigate corrosion risks.

Non-welded steel pipe joints are required to be electrically bonded for continuity. Testing of the bonded joints by a National Association of Corrosion Engineers International-certified technician is required using a specific test method and criteria for evaluation of results. A CP test station is required at every isolation joint location, and every 1,000 feet.
 DIP and Fittings: Guidelines for coating specifications for buried ductile iron piping necessitate the application of a polyethylene encasement system, and manufacturers standard asphaltic coating, as outlined in AWWA C105. However, the soil corrosivity will dictate the type of coating that is required.

Furthermore, both buried ductile and steel piping accessories will be coated with an epoxy system.

Specific components, such as buried insulating flanges, metallic surfaces associated with nonmetallic pipes, and DIP sections not having cathodic protection anodes, will use a wax tape coating system in accordance with AWWA C217.
 It is recommended to enhance protection by incorporating joint bonds, designated test stations to monitor corrosion conditions, and CP systems to safeguard against corrosion.  Steel or Cast/Ductile Iron Fittings in Nonmetallic Pipe: For fittings made from steel or cast/ductile iron, apply durable protective coatings, such as fusion-bonded epoxy, which forms a strong bond with the metal surface, providing enhanced resistance to corrosion. After assembling the system, ensure all steel fasteners are coated with a protective layer, such as wax tape or a comparable barrier, to shield them from environmental elements. Additionally, for larger diameter fittings or those in critical applications, consider using supplemental galvanic anodes that provide extra corrosion protection.  Miscellaneous Steel or Cast/Ductile Iron Components: For any miscellaneous steel or cast/ductile iron parts, usage of robust protective coatings, including epoxy, fusion-bonded epoxy, or wax tape, is strongly recommended. These coatings effectively prevent moisture penetration and mitigate corrosion. In high-risk or critical applications, provide supplemental protection through galvanic anodes to enhance the overall corrosion resistance of these components.  Lining: The selection of the appropriate lining material will be primarily influenced by the results of the current water quality testing being conducted. This testing will assess various parameters, such as pH levels, conductivity, alkalinity, total dissolved solid, calcium, temperature, magnesium, chloride, and sulfate. Additionally, consideration will be given to any historical data that may indicate the effectiveness of different lining materials used in similar conditions in the past.  Electrical Isolation: To facilitate the effectiveness of the CP systems, all buried metallic pipelines necessitate electrical isolation from buildings and electrically grounded equipment. Insulating joints must be strategically placed in accessible locations to allow for testing and maintenance. It is advisable to avoid direct buried insulated flanges, when possible, given the challenges associated with repairing insulating components.  Electrical isolation devices are used to establish an electrical break between two structures mechanically jointed to avoid losing CP current to other structures not intended to be cathodically protected. Electrical isolation devices may be flange isolation kits or prefabricated monolithic isolation joints.  A CP system is considered electrically shorted when the CP current is lost to unintended paths; such losses affect the performance of the CP system. A cathodically protected pipeline system must be electrically isolated at its extents and at all metallic connections along its length to ensure the CP current is not lost to other piping systems, grounding systems, or unintended assets. This can be accomplished by strategically placing electrical isolation devices throughout the facility to prevent current drain to unintended structures, which could detrimentally affect the protection status of the system.

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5.10.3.1.2 Cathodic Protection
Protective coatings have a propensity to deteriorate over an extended period. This deterioration is primarily attributed to age, changes in the soil environment because of seasonal variations, soil corrosivity, and other factors. Based on the susceptibility of the coating to degrade with time, buried steel structures, such as pipelines, flanges, and similar, need regular assessment to ascertain whether the structure’s coating conditions and integrity are maintained. The longer the steel structures stay buried in the ground, the greater their susceptibility to corrosion damage and degradation. Buried pipeline coatings can degrade over time, especially if structures are put into an environment for which they were not designed (if they are exposed to excessive temperatures, pH, or chemicals or encounter soil stress, mechanical damage, and pressure reversals).

The protection given to a pipeline by protective coating is greatly influenced by discontinuities or holidays in the coating film. At discontinuous areas in the coating film, the pipeline is most susceptible to external corrosion, thus creating the necessity for a secondary protective system. The corrosion rate at discontinuous areas may be affected by factors, such as the coating substrate, the coating thickness, the electrolytes present at the discontinuity, and surface preparation. A combination of coating and CP will produce a more synergistic effect in mitigating corrosion.

CP of yard piping is required for buried steel and ductile iron using galvanic anodes. The theoretical conceptualization of galvanic CP systems is predicated on the simple application of dissimilar metal corrosion cells. The electrochemical process involves electrically connecting a steel structure to a metal higher in the electrochemical series (active metal) in the presence of a common conductive electrolyte, such as soil. The most active metal (anode) preferentially corrodes, consequently, dissipating CP current simultaneously.

The CP design will meet all the following principal design objectives:
 Provide sufficient current density on a continuous basis to ensure the steel surfaces are polarized to an acceptable criteria and uniform current distribution is applied on the external surfaces of the subject pipelines.
 Ensure the safety of the public and operating personnel and adhere to all applicable codes and standards.  Ensure the selected current capacity is sufficient to effectively polarize the pipeline exterior surfaces available even after considerable coating deterioration, typically 5% to 10% for a 30-year system design life.
 Ensure the impressed current CP anodes are strategically placed in a location that is unaffected by freezing.
 Avoid polarization of the external surfaces of the subject pipelines to greater than -1,200 millivolts with respect to copper- copper sulfate reference electrode, thereby minimizing coating disbondment.  Ensure circuit redundancy within the CP system.
 Ensure a minimum design life of 30 years.

5.10.3.1.3 Cathodic Protection Design Life
The CP system will be designed to last a minimum of 30 years. Following its commissioning, it is advised to conduct regular maintenance and inspections. As the system nears anode depletion, it is recommended to reassess and replace the anodes as necessary.

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The lifespan of the anodes is directly linked to their current output. The theoretical design life of the CP system is also based on assuming constant current requirements and circuit resistance. However, real-world factors, such as potential further degradation of the coating or additional current loss to metallic sections, could affect this estimation.

5.10.4 Painting and Protective Coatings
Table 5-15 presents a succinct description of the painting and protective coating systems.

These requirements adhere to industry standards and aim to ensure durable service for various applications.

Through deliberate and systematic categorization of coating systems according to their intended purposes, Table 5-15 offers a clear guideline for choosing an appropriate coating tailored to specific applications.

Table 5-15. Protective Coating Systems
No. Surface Exposure Coating Materials
Surface
Preparation[a]
No.

Coats Thickness[b]
2 Submerged
metal
Nonpotable
water
Epoxy SP 5 2 16 millimeters
4 Exposed
metal
Highly corrosive Epoxy/Polyurethane SP 10 3 9.5 millimeters 7 Encased
metal
Concrete
embedment
Epoxy SP 6 2 16 millimeters
8 Buried steel Soil Epoxy SP 10 2 16 millimeters
10 Nonferrous
metal
Exposed Epoxy SP 16 1[c] As required by
manufacturer
19a Exposed
metals from
concrete
removal
Nonpotable
water
Amine-cured epoxy SP 11 2 16 millimeters
21 Concrete Exposed Epoxy nonskid
(aggregated)
SP 13 1 160 ft2/gal
25 FRP, PVC Exposed Acrylic latex SP 1 2 640 ft2/gal
27 Aluminum Concrete or
metal contact
Bituminous paint SP 1 1 10 millimeters
29 Steel As specified Fusion-bonded epoxy SP 10 1 to 2 7 millimeters 29A Steel dowels Concrete
embedment
Fusion-bonded epoxy SP 10 1 to 2 7 millimeters
109 Concrete
masonry
Exposed, semiglossAcrylic latex Clean 3 555 ft2/gal
115 Gypsum
drywall
Indoor Acrylic latex Clean 3 1,150 ft2/gal
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No. Surface Exposure Coating Materials
Surface
Preparation[a]
No.

Coats Thickness[b]
116 Gypsum
drywall
Indoor Water-based epoxy Clean 2 600 ft2/gal
117 Concrete
masonry
Exposed Acrylic latex Clean 3 675 ft2/gal
[a] SP designations refer to Society for Protective Coatings standards. [b] Thickness values are slightly variable and a result of the ft2/gal coverage for coatings on nonmetallic structures, as opposed to dry film thickness in milliliter for metallic structures.
[c] Top coating according to the exposure is also required. ft2/gal = square foot (feet) per gallon
Certain equipment and structures come exclusively with coating systems applied at the manufacturer’s factory. The selection of these systems is based on ensuring durability aligned with the specific project requirements. This approach aims to integrate coatings seamlessly into the equipment or structure, providing a reliable and long-lasting protective layer.

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6. References
American Society of Civil Engineers (ASCE). n.d. ASCE Hazard Tool. Accessed 2025.

Canadian Association of Petroleum Producers (CAPP). 2018. Pipeline Corrosion Management. Calgary, Alberta.

City of Crescent City (City). 2001. Crescent City General Plan.

City of Crescent City (City). 2023. 2022-2030 Housing Element Update. April.

Delattre, Marc, and Anne Rosinski. 2012. Preliminary geologic map of onshore portions of the Crescent City and Orick 30' x 60' quadrangles, California. Scale 1:100,000. California Geological Survey. Preliminary Geologic Maps PGM-12-05.

Federal Emergency Management Agency (FEMA). 2017. FEMA Flood Insurance Rate Map #06015C0327F, Del Norte County, California and Incorporated Areas.

Federal Emergency Management Agency (FEMA). 2018. Flood Insurance Study, Del Norte County, California and Incorporated Areas #06015CV000C.

GeoVision. 2004. Report of Geotechnical Engineering Services, Crescent City Water Treatment Plant, Crescent City, California. Prepared for Brown and Caldwell. December 3.

Jacobs. 2025. Project Report.

U.S. Army Corps of Engineers (USACE). 1978. Technical Report H-78-26.

Water Environment Federation (WEF). 2025. Design of Water Resource Recovery Facilities, Manual of Practice 8, 7th Edition.

Peck, Ralph B., Walter E. Hanson, and Thomas H. Thornburn. 1974. Foundation Engineering. Second edition.

Revie, Winston R. 2000. Uhlig’s Corrosion Handbook. Second edition.

Roberge, P. R. 2008. Corrosion Engineering: Principles and Practice. New York: McGraw-Hill.

U.S. Census Bureau. n.d. ACS Demographic and Housing Estimates. https://data.census.gov/table/ACSDP5Y2023.DP05?q=crescent+city.

RBC Capital Upgrade and Biosolids/Digester Optimization Project Basis of Design Report / 10% Design
Appendix A
National Pollutant Discharge
Elimination System Permit
R1-2023-0039
WASTE DISCHARGE REQUIREMENTS 1

CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD

NORTH COAST REGION
5550 Skylane Blvd, Suite A
Santa Rosa, CA 95403-1072
Phone (707) 576-2220 • Fax (707) 523-0135
California State Water Resources Control Board Website
(http://www.waterboards.ca.gov)
ORDER NO. R1-2023-0039
NPDES NO. CA0022756
WDID NO. 1A84006ODN
Waste Discharge Requirements and Water Recycling Permit for the
City of Crescent City
Wastewater Treatment Facility
Del Norte County
The following Permittee is subject to waste discharge requirements (WDRs) set forth in this Order:

Permittee City of Crescent City
Name of Facility Wastewater Treatment Facility
Facility Address 210 Battery Street
Crescent City, CA 95531
Del Norte County
Table 1. Discharge Location
Discharge
Point Effluent Description
Discharge
Point
Latitude
(NorthSouth)
Discharge
Point
Longitude
(East-West)
Receiving Water
001 Secondary treated
wastewater 41˚44’ 38” 124˚12’ 10” Pacific Ocean
002 Tertiary treated
wastewater -- --
Recycled Water
System
This Order was adopted on: December 12, 2023
This Order shall become effective on: February 1, 2024
This Order shall expire on: January 31, 2029
WASTE DISCHARGE REQUIREMENTS 2
The Permittee shall file a Report of Waste Discharge as an application for reissuance of WDRs in accordance with title 23, California Code of Regulations, and an application for reissuance of a National Pollutant Discharge Elimination System (NPDES) permit no later than: January 31, 2028. The U.S. Environmental Protection Agency (U.S. EPA) and the California Regional Water Quality Control Board, North Coast Region have classified this discharge as follows: Major
I, Valerie M. Quinto, Executive Officer, do hereby certify that this Order with all attachments is a full, true, and correct copy of the Order adopted by the California Regional Water Quality Control Board, North Coast Region, on the date indicated above.
_______________________________________
Valerie M. Quinto, Executive Officer
CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
WASTE DISCHARGE REQUIREMENTS 3

TABLE OF CONTENTS

1. Facility Information .................................................................................................. 5

2. Findings................................................................................................................... 5

2.1. Legal Authorities................................................................................................... 5

2.2. Background and Rationale for Requirements....................................................... 5

2.3. Provisions and Requirements Implementing State Law ....................................... 5

2.4. Notification of Interested Parties........................................................................... 5

2.5. Consideration of Public Comment ........................................................................ 6

2.6. Anticipated Water Quality Impacts in Disadvantaged or Tribal Communities......................................................................................................... 6

3. Discharge Prohibitions ............................................................................................ 7

4. Effluent Limitations and Discharge Specifications................................................... 7

4.1. Effluent Limitations – Discharge Point 001 ........................................................... 8

4.2. Land Discharge Specifications – Not Applicable ................................................ 11

4.3. Recycling Specifications – Discharge Point 002................................................. 11

4.4. Other Requirements ........................................................................................... 16

5. Receiving Water Limitations.................................................................................. 16

5.1. Surface Water Limitations .................................................................................. 16

5.2. Groundwater Limitations..................................................................................... 19

6. Provisions.............................................................................................................. 20

6.1. Standard Provisions. .......................................................................................... 20

6.2. Monitoring and Reporting Program (MRP) Requirements .................................. 21

6.3. Special Provisions .............................................................................................. 21

7. Compliance Determination.................................................................................... 28

TABLE OF TABLES
Table 1. Discharge Location............................................................................................ 1 Table 2. Effluent Limitations1........................................................................................... 9 Table 3. Recycled Water Discharge Specifications1...................................................... 12

TABLE OF ATTACHMENTS
Definitions............................................................................................A-1 Map......................................................................................................B-1 Flow Schematic .................................................................................. C-1 Standard Provisions ........................................................................... D-1 Monitoring and Reporting Program......................................................E-1 CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
WASTE DISCHARGE REQUIREMENTS 4
Fact Sheet ...........................................................................................F-1 CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
WASTE DISCHARGE REQUIREMENTS 5

1. FACILITY INFORMATION
Information describing the City of Crescent City (Permittee), Wastewater Treatment Facility (Facility) is summarized on the cover page and in sections 1 and 2 of the Fact Sheet (Attachment F). Section 1 of the Fact Sheet also includes information regarding the Facility’s permit application.

2. FINDINGS
The California Regional Water Quality Control Board, North Coast Region (Regional Water Board), finds:

2.1. Legal Authorities
This Order serves as waste discharge requirements (WDRs) pursuant to article 4, chapter 4, division 7 of the California Water Code (commencing with section 13260). This Order is also issued pursuant to section 402 of the federal Clean Water Act (CWA) and implementing regulations adopted by the U.S. EPA and chapter 5.5, division 7 of the Water Code (commencing with section 13370). It shall serve as a National Pollutant Discharge Elimination System (NPDES) permit authorizing the Permittee to discharge into waters of the United States at the discharge location described in Table 1 subject to the WDRs in this Order. This Order also serves as a Master Recycling Permit pursuant to article 4, chapter 7, division 7 of the Water Code (commencing with section 13500).

2.2. Background and Rationale for Requirements
The Regional Water Board developed the requirements in this Order based on information submitted as part of the application, through monitoring and reporting programs, and other available information. The Fact Sheet (Attachment F), which contains background information and rationale for the requirements in this Order, is hereby incorporated into and constitutes Findings for this Order. Attachments A through E are also incorporated into this Order.

2.3. Provisions and Requirements Implementing State Law The provisions/requirements in subsections 3.11, 4.2, 4.3, 4.4, 5.2, and 6.3.4.3 of this Order and sections 7, 9.1, 9.3, and 10.6 of the MRP are included to implement state law only. These provisions/requirements are not required or authorized under the federal CWA; consequently, violations of these provisions/requirements are not subject to the enforcement remedies that are available for NPDES violations.

2.4. Notification of Interested Parties
The Regional Water Board has notified the Permittee and interested agencies and persons of its intent to prescribe WDRs for the discharge and has provided them CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
WASTE DISCHARGE REQUIREMENTS 6
with an opportunity to submit their written comments and recommendations.

Details of the notification are provided in the Fact Sheet.

2.5. Consideration of Public Comment
The Regional Water Board, in a public meeting, heard and considered all comments pertaining to the discharge. Details of the Public Hearing are provided in the Fact Sheet.

2.6. Anticipated Water Quality Impacts in Disadvantaged or Tribal Communities The Permittee, the City of Crescent City, operates a wastewater treatment facility within a disadvantaged community located along the Pacific Ocean in Del Norte County. The discharge is classified as "major" under federal regulations. Among other updates, this renewed permit contains new requirements to implement bacteria objectives for ocean waters used for water contact recreation and shellfish harvesting. Expanded monitoring and reporting requirements are also included in the renewed Order to monitor compliance with applicable water quality objectives. The Order does not contain a time schedule for meeting applicable water quality objectives, an alternative compliance path that allows time to come into compliance with water quality objectives, or a water quality variance (Wat.

Code, section 13149.2, subd. (d)); all requirements must be met upon Order adoption.

The Regional Water Board publicly noticed the permit and provided opportunities for public comment. Public notice was provided to interested persons and public agencies in the region with jurisdiction over natural resources in the affected area, including the Del Norte County Community Development Department. While the discharge regulated by this Order is not expected to result in disproportionate impacts on water quality in tribal or disadvantaged communities, the Regional Water Board has conducted outreach consistent with Water Code section 189.7.

THEREFORE, IT IS HEREBY ORDERED, that Order No. R1-2017-0002 is rescinded upon the effective date of this Order except for enforcement purposes, and, in order to meet the provisions contained in division 7 of the Water Code (commencing with section 13000) and regulations adopted thereunder, and the provisions of the CWA and regulations and guidelines adopted thereunder, the Permittee shall comply with the requirements in this Order. This action in no way prevents the Regional Water Board from taking enforcement action for violations of the previous Order.

CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
WASTE DISCHARGE REQUIREMENTS 7

3. DISCHARGE PROHIBITIONS

3.1. The discharge of any waste not disclosed by the Permittee or not within the reasonable contemplation of the Regional Water Board is prohibited.

3.2. Creation of pollution, contamination, or nuisance, as defined by section 13050 of the Water Code is prohibited.

3.3. The discharge of sludge or digester supernatant is prohibited, except as authorized under section 6.3.4.2 of this Order (Sludge Disposal and Handling Requirements).

3.4. The discharge or recycling use of untreated or partially treated waste (receiving a lower level of treatment than described in section 2.1 of the Fact Sheet) from anywhere within the collection, treatment, or disposal systems is prohibited, except as provided for in Attachment D, Standard Provisions 1.7 (Bypass) and 1.8 (Upset).

3.5. The discharge of waste to land that is not owned by the Permittee, governed by City ordinance, or under agreement to use by the Permittee, or for which the Permittee has explicitly permitted such use, is prohibited, except for use for fire suppression as provided in title 22, sections 60307(a) and 60307(b) of the California Code of Regulations (CCR).

3.6. The discharge of waste at any point not described in Finding 2.2 of the Fact Sheet or authorized by a permit issued by the State Water Resources Control Board (State Water Board) or another Regional Water Board is prohibited.

3.7. The average dry weather flow of waste through the Facility shall not exceed 1.86 mgd, measured daily and averaged over a calendar month. The peak daily wet weather flow of waste through the Facility shall not exceed 6.12 mgd, measured daily. Compliance with this prohibition shall be determined as defined in sections

7.11 and 7.12 of this Order.

3.8. The discharge of any radiological, chemical, or biological warfare agent or highlevel radioactive waste into waters of the state is prohibited.

3.9. The discharge of sludge directly into the ocean or into a waste stream that discharges to the ocean is prohibited.

3.10. The by-passing of untreated wastes containing concentrations of pollutants in excess of those of Ocean Plan Tables 3 or 4 (2019) is prohibited.

3.11. The acceptance of septage to a location other than an approved septage receiving station is prohibited.

4. EFFLUENT LIMITATIONS AND DISCHARGE SPECIFICATIONS
CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
WASTE DISCHARGE REQUIREMENTS 8

4.1. Effluent Limitations – Discharge Point 001

4.1.1. Final Effluent Limitations – Discharge Point 001

4.1.1.1. The Permittee shall maintain compliance with the following effluent limitations at Discharge Point 001, with compliance measured at Monitoring Location EFF-001 as described in the Monitoring and Reporting Program (MRP), Attachment E:

CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
WASTE DISCHARGE REQUIREMENTS 9
Table 2. Effluent Limitations1
Parameter Units Average
Monthly
Average
Weekly
Maximum
Daily
Instantaneous
Minimum
Instantaneous
Maximum
Six-Month
Median
Biochemical
Oxygen Demand
5-day @ 20°C
(BOD5)
mg/L 30 45 -- -- -- --
Total Suspended
Solids mg/L 30 45 -- -- -- --
pH standard
units
-- -- -- 6.0 9.0 --
Oil and Grease mg/L 25 40 -- -- 75 --
Ammonia
Nitrogen, Total (as
N)
mg/L -- -- 72 -- 180 18
Settleable Solids mL/L 1.0 1.5 -- -- 3.0 --
Turbidity NTU 75 100 -- -- 225 --
Copper, Total
Recoverable μg/L -- -- 300 -- 840 32
Silver, Total
Recoverable μg/L -- -- 79 -- 200 16
Endosulfan4 μg/L -- -- 0.54 -- 0.81 0.27
Endrin μg/L -- -- 0.12 -- 0.18 0.060
Total Residual
Chlorine5 μg/L -- -- 240 -- 1800 60
DDT6 μg/L 0.0051 -- -- -- -- --
CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
WASTE DISCHARGE REQUIREMENTS 10
Parameter Units Average
Monthly
Average
Weekly
Maximum
Daily
Instantaneous
Minimum
Instantaneous
Maximum
Six-Month
Median
Heptachlor μg/L 0.0015 -- -- -- -- --
Dieldrin μg/L 0.0012 -- -- -- -- --
Table Notes

1. See Definitions in Attachment A and Compliance Determination discussion in section 7 of this Order.

2. The sum of the concentrations of endosulfan-alpha, endosulfan-beta, and endosulfan sulfate, as identified in Attachment A of this Order and Appendix I of the Ocean Plan under the Endosulfan definition.

3. See section 7.12 of this Order regarding compliance with chlorine residual effluent limitations.

4. The sum of the concentrations of 4,4’DDT, 2,4’DDT, 4,4’DDE, 2,4’DDE, 4,4’DDD, and 2,4’DDD.

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4.1.1.2. Percent Removal: The average monthly percent removal of BOD5 and total suspended solids shall not be less than 85 percent. Percent removal shall be determined from the monthly average value of influent wastewater concentration in comparison to the monthly average value of effluent concentration for the same constituent over the same time period as measured at Monitoring Locations INF-001 and EFF-001, respectively.

4.1.1.3. Disinfection: Disinfected effluent discharged from the wastewater treatment plant through Discharge Point 001 to the Pacific Ocean shall not contain fecal coliform bacteria exceeding the following concentrations, as measured at Monitoring Location EFF-001:

4.1.1.3.1. Enterococci

4.1.1.3.1.1. The 6-week rolling geometric mean of enterococci shall not exceed 30 colony forming units (CFU) per 100 mL; and

4.1.1.3.1.2. No sample shall exceed a CFU of 110 per 100 mL.

4.1.1.3.2. Total Coliform Organisms

4.1.1.3.2.1. The median value of total coliform bacteria shall not exceed an MPN of 70 per 100 mL in a calendar month; and

4.1.1.3.2.2. Not more than 10 percent of the samples collected in a calendar month shall exceed an MPN of 230 per 100 mL.

4.1.1.3.3. Fecal Coliform

4.1.1.3.3.1. The 30-day geometric mean of fecal coliform density not to exceed 200 per 100 mL;

4.1.2. Interim Effluent Limitations – Not Applicable
This Order does not establish interim effluent limitations or schedules for compliance with final limitations.

4.2. Land Discharge Specifications – Not Applicable
This Order does not authorize discharges to land.

4.3. Recycling Specifications – Discharge Point 002

4.3.1. When discharging to the recycled water system, the Permittee shall maintain compliance with the following limitations at Discharge Point 002, with compliance measured at Monitoring Location REC-001, as described in the attached MRP.

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Table 3. Recycled Water Discharge Specifications1
Parameter Units Average
Monthly
Average
Weekly
Maximum
Daily
Instantaneous
Minimum
Instantaneous
Maximum
Biochemical Oxygen
Demand 5-day @ 20°C mg/L 10 15 -- -- --
Total Suspended Solids mg/L 10 15 -- -- --
Settleable Solids mL/L 0.1 -- 0.2 -- --
pH standard
units -- -- -- 6.0 9.0
Table Notes

1. See Definitions in Attachment A and Compliance Determination discussion in section 7 of this Order.

4.3.1.1. Disinfection: Disinfected effluent discharged from the Facility to the recycled water system at Discharge Point 002 shall not contain total coliform bacteria exceeding the following concentrations, as measured at Monitoring Location REC-001:

4.3.1.1.1. The median concentration shall not exceed an MPN of 2.2 per 100 mL, using the bacteriological results of the last 7 days for which analysis have been completed:

4.3.1.1.2. The number of total coliform bacteria shall not exceed an MPN of 23 per 100 mL, in more than one sample in any 30-day period; and

4.3.1.1.3. No sample shall exceed an MPN of 240 total coliform bacteria per 100 mL.

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4.3.2. Water Recycling Requirements

4.3.2.1. This Order includes water recycling requirements that apply to the production of recycled water. The Permittee shall obtain permit coverage for the use of recycled water, prior to initiating recycled water use.

4.3.2.2. The Permittee shall comply with applicable state and local requirements regarding the production and use of recycled water, including requirements of Water Code sections 13500 – 13577 (Water Reclamation) and State Water Board, Division of Drinking Water (DDW) regulations at title 22, sections 60301 – 60357 of the CCR (Water Recycling Criteria).

4.3.3. Filtration Process Requirements

4.3.3.1. Filtration Rate. When discharging to the recycled water system, the rate of filtration through the tertiary filters, as measured at Monitoring Location INT001A, shall not exceed 5 gallons per minute per square foot of surface area or other filtration rates authorized in writing by the Regional Water Board Executive Officer and under conditions recommended by DDW.

4.3.3.2. Turbidity. When discharging to the recycled water system, the effluent from the filtration system shall at all times be filtered such that the filtered effluent does not exceed any of the following specifications at Monitoring Location INT-001B prior to discharge to the disinfection unit:

4.3.3.2.1. 0.2 NTU more than 5 percent of the time during any 24-hour period; and

4.3.3.2.2. 0.5 NTU at any time.

4.3.3.3. Filtered effluent in excess of the turbidity specifications shall not enter the recycling distribution system. Filtered effluent in excess of turbidity specifications shall be automatically diverted to an upstream treatment process unit or to emergency storage as soon as the Permittee is aware of the exceedance. The Permittee shall provide notification of non-compliance with the filtration process requirements as required in section 9.3.2.3 of the MRP (Attachment E).

4.3.4. Disinfection Process Requirements
When discharging to the recycled water system, the Permittee shall operate the ultraviolet light (UV) disinfection system in accordance with the operating protocol and technical and administrative requirements set out by DDW in order to ensure compliance with disinfection water recycling specifications in section

4.3.1.2 of this Order. Specifically, the Permittee shall:

4.3.4.1. Disinfect tertiary treated wastewater using a disinfection process that, when combined with the filtration process, has been demonstrated to inactivate and/or remove 99.999 percent of the plaque forming units of F-specific CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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bacteriophage MS2, or polio virus in the wastewater. At a minimum, the Permittee shall demonstrate a 99.99 percent removal and/or inactivation of MS2 through the UV disinfection system only.

4.3.4.2. Provide continuous, reliable monitoring of flow, UV transmittance, UV intensity, UV dose, and UV power at Monitoring Location INT-002B, and turbidity at Monitoring Location INT-001B. The Permittee must demonstrate compliance with the UV dose requirement.

4.3.4.3. Operate the UV disinfection system to provide a minimum UV dose of 80 millijoules per square centimeter (mJ/cm2) at all times at Monitoring Location INT-002B, unless otherwise approved by DDW.

4.3.4.4. The equations below must be used as part of the automatic UV disinfection control system for calculating UV dose.

RED = 10(1.49425 - 0.38577 * log (Q) -0.51275 * log (UVA) +0.40133*log (sensor))
And
Sensor Intensity High power = 10.465 (UVT) - 412.2
OR

4.3.4.5. Sensor Intensity Low power = 7.8655 (UVT) - 302.29 Where:

RED = Delivered UV dose per Reactor (mJ/cm2);
Q = flow in gpm [gallons per minute];
UVA = UV absorbance at 254 nm (%);
UVT = % UV transmittance at 254 nm (%).

4.3.4.6. Ensure that the UV transmittance (at least 254 nanometers) in the wastewater does not fall below 65 percent of maximum at any time, unless otherwise approved by DDW.

4.3.4.7. Visually inspect the quartz sleeves and cleaning system components per the manufacturer’s operation manual for physical wear (scoring, solarization, seal leaks, etc.) and to check the efficacy of the cleaning system.

4.3.4.8. Wipe/clean the quartz sleeves at least once every 24 hours following the manufacturer’s procedures to ensure the minimum required UV dose delivery is consistently achieved. Cleaning intervals shall be increased as necessary CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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to ensure compliance with permit requirements such as UV dose and total coliform organism requirements.

4.3.4.9. Operate the UV disinfection system in accordance with an approved operations and maintenance plan, which specifies clearly the operational limits and responses required for critical alarms. The Permittee shall maintain a copy of the approved operations plan at the treatment plant and make the plan readily available to operations personnel and regulatory agencies. The Permittee shall post a quick reference plant operations data sheet at the treatment plant. The data sheet shall include the following information:

4.3.4.9.1. The alarm set points for secondary and tertiary turbidity, high and low flow, UV dose and transmittance, UV lamp operations hours, and power.

4.3.4.9.2. The values of secondary and tertiary turbidity, high and low flow, UV dose and transmittance, UV lamp operation hours, and power when flow must be diverted to waste.

4.3.4.9.3. The values of high daily and weekly median total coliform when an operational response must be taken.

4.3.4.9.4. The required frequency of calibration for all meters measuring turbidity, flow, UV transmittance, and power.

4.3.4.9.5. The required frequency of mechanical cleaning/wiping and equipment inspection.

4.3.4.9.6. The UV lamp age tracking procedures and replacement intervals.

4.3.4.10. Replace lamps every 7,000 hours of operation, or sooner, if there are indications that the lamps are failing to provide adequate disinfection. The Permittee shall maintain lamp age and lamp replacement records for a time period consistent with the record retention requirements in the Standard Provisions (Attachment D, Section 4).

4.3.4.11. Properly calibrate flow meters and UV transmittance (UVT) monitors to ensure proper disinfection.

4.3.4.12. Inspect the UVT meter and check against a reference bench-top unit weekly to document accuracy.

4.3.4.13. Recalibrate the on-line UVT analyzer by a procedure recommended by the manufacturer if the on-line analyzer UVT reading varies from the bench-top spectrophotometer UVT reading by 2 percent or more.

4.3.4.14. Operate the UV disinfection system with a built-in automatic reliability feature that must be triggered when the system is below the target UV dose. If the measured UV dose goes below the minimum UV dose, the UV reactor in CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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question must alarm and startup the next available row of UV lamps or UV lamp bank.

4.3.4.15. Not allow equivalent or substitutions of equipment to occur without an adequate demonstration of equivalent disinfection performance to the satisfaction and approval of DDW.

4.3.4.16. Until adequate redundancy and reliability is provided and demonstrated, ensure that flow through the UV disinfection system does not exceed 0.6 mgd as a daily maximum. Upon demonstration of adequate redundancy and reliability, ensure that flow through the UV disinfection system does not exceed 1.2 mgd as a daily maximum, unless otherwise approved by DDW.

4.4. Other Requirements

4.4.1. Total Residual Chlorine, Monitoring Location INT-002A. As measured at the end of the chlorine contact tank at Monitoring Location INT-002A, the total residual chlorine concentration shall be maintained at a concentration that ensures the discharge meets the effluent limitations for total coliform, fecal coliform, and enterococci bacteria at the end of the disinfection process for discharges to Discharge Point 001.

5. RECEIVING WATER LIMITATIONS
Receiving water limitations are based on water quality objectives contained in the Ocean Plan (Surface Water Limitations) and the Basin Plan (Groundwater) are a required part of this Order. Receiving water conditions not in conformance with the limitation are not necessarily a violation of this Order. Compliance with receiving water limitations shall be measured at monitoring locations described in the MRP (Attachment E). The Regional Water Board may require an investigation to determine cause and culpability prior to asserting that a violation has occurred and/or may consider other available information.

5.1. Surface Water Limitations
Discharges from the Facility shall not cause the following in the receiving water upon completion of initial dilution:

5.1.1. Ocean Plan

5.1.1.1. Bacteria Characteristics

5.1.1.1.1. Water-Contact Standards. Within a zone bounded by the shoreline and a distance of 1,000 feet from the shoreline or the 30-foot depth contour, whichever is further from the shoreline, and in areas outside this zone designated for water contact recreation use by the Regional Water Board, but including all kelp beds, the following bacteriological objectives shall be maintained throughout the water column:

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5.1.1.1.1.1. A 30-day geometric mean of fecal coliform density not to exceed 200 per 100 mL, calculated based on the five most recent samples from each site, and a single sample maximum not to exceed 400 per 100 mL.

5.1.1.1.1.2. A 6-week rolling geometric mean of enterococci not to exceed 30 CFU per 100 mL, calculated weekly, and a statistical threshold value of 110 CFU per 100 mL not to be exceeded by more than 10 percent of the samples collected in a calendar month, calculated in a static manner.

5.1.1.1.2. Shellfish Harvesting Standards. At all areas where shellfish may be harvested for human consumption, as determined by the Regional Water Board, the following bacterial objectives shall be maintained throughout the water column:

5.1.1.1.2.1. The median total coliform density shall not exceed 70 per 100 mL, and not more than 10 percent of the samples shall exceed 230 per 100 mL.

5.1.1.1.3. Physical Characteristics

5.1.1.1.3.1. Floating particulates and oil and grease shall not be visible.

5.1.1.1.3.2. The discharge of waste shall not cause aesthetically undesirable discoloration of the ocean surface.

5.1.1.1.3.3. Natural light shall not be significantly reduced at any point outside the initial dilution zone as the result of the discharge of waste.

5.1.1.1.3.4. The rate of deposition of inert solids and the characteristics of inert solids in ocean sediments shall not be changed such that benthic communities are degraded.

5.1.1.1.4. Chemical Characteristics

5.1.1.1.4.1. The dissolved oxygen concentration shall not at any time be depressed more than 10 percent from that which occurs naturally, as the result of the discharge of oxygen demanding waste materials.

5.1.1.1.4.2. The pH shall not be changed at any time more than 0.2 units from that which occurs naturally.

5.1.1.1.4.3. The dissolved sulfide concentration of waters in and near sediments shall not be significantly increased above that present under natural conditions.

5.1.1.1.4.4. The concentration of substances set forth in Chapter II, Table 3 of the Ocean Plan shall not be increased in marine sediments to levels which would degrade indigenous biota.

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5.1.1.1.4.5. The concentration of organic materials in marine sediments shall not be increased to levels that would degrade marine life.

5.1.1.1.4.6. Nutrient materials shall not cause objectionable aquatic growths or degrade indigenous biota.

5.1.1.1.4.7. Discharges shall not cause exceedances of water quality objectives for ocean waters of the state established in Chapter II, Table 3 of the Ocean Plan.

5.1.1.1.5. Radiological Standards

5.1.1.1.5.1. The discharge of radioactive waste shall not degrade marine life.

5.1.1.1.6. Biological Characteristics

5.1.1.1.6.1. Marine communities, including vertebrate, invertebrate and plant species, shall not be degraded.

5.1.1.1.6.2. The natural taste, odor, and color of fish, shellfish, or other marine resources used for human consumption shall not be altered.

5.1.1.1.6.3. The concentration of organic materials in fish, shellfish, or other marine resources used for human consumption shall not bioaccumulate to levels that are harmful to human health.

5.1.1.1.7. General Standards

5.1.1.1.7.1. The discharge shall not cause a violation of any applicable water quality standard for the receiving waters adopted by the Regional Water Board or the State Water Board as required by the CWA and regulations adopted thereunder.

5.1.1.1.7.2. Waste management systems that discharge to the ocean must be designed and operated in a manner that will maintain the indigenous marine life and a healthy and diverse marine community.

5.1.1.1.7.3. Waste discharged to the ocean must be essentially free of:

5.1.1.1.7.3.1. Material that is floatable or will become floatable upon discharge.

5.1.1.1.7.3.2. Settleable material or substances that may form sediments which will degrade benthic communities or other aquatic life.

5.1.1.1.7.3.3. Substances which will accumulate to toxic levels in marine waters, sediments or biota.

5.1.1.1.7.3.4. Substances that significantly decrease the natural light to benthic communities and other marine life.

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5.1.1.1.7.3.5. Materials that result in aesthetically undesirable discoloration of the ocean surface.

5.1.1.1.7.4. Waste effluents shall be discharged in a manner which provides sufficient initial dilution to minimize the concentrations of substances not removed in the treatment.

5.1.1.1.7.5. Location of waste discharges must be determined after a detailed assessment of the oceanographic characteristics and current patterns to assure that:

5.1.1.1.7.5.1. Pathogenic organisms and viruses are not present in areas where shellfish are harvested for human consumption or in areas used for swimming or other body-contact sports.

5.1.1.1.7.5.2. Natural water quality conditions are not altered in areas designated as being of special biological significance or areas that existing marine laboratories use as a source of seawater.

5.1.1.1.7.5.3. Maximum protection is provided to the marine environment.

5.1.1.1.7.5.4. The discharge does not adversely affect recreational beneficial uses such as surfing and beach walking.

5.2. Groundwater Limitations

5.2.1. The collection, treatment, storage, and disposal of wastewater or use of recycled water shall not cause a statistically significant degradation of groundwater quality unless a technical evaluation is performed that demonstrates that any degradation that could reasonably be expected to occur, after implementation of all regulatory requirements (e.g., title 27 of the CCR) and reasonable BMPs, will not violate groundwater quality objectives or cause impacts to beneficial uses of groundwater.

5.2.2. The collection, treatment, storage, and disposal of wastewater or use of recycled water shall not cause alterations of groundwater that contain chemical concentrations in excess of limits specified in title 22, division 4, chapter 15, article 4, sections 64431; article 5.5, section 64444; and article 16, section 64449 of the CCR, and the Basin Plan.

5.2.3. The collection, treatment, storage, and use of wastewater or recycled water shall not cause or contribute to levels of radionuclides in groundwater in concentrations that cause nuisance or adversely affect beneficial uses, nor in excess of the MCLs and SMCLs established for these pollutants in title 22, division 4, chapter 15, article 5, sections 64442 and 64443 of the CCR.

5.2.4. The collection, treatment, storage, and disposal of wastewater or use of recycled water shall not cause groundwater to contain taste - or odor-producing CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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substances in concentrations that cause nuisance or adversely affect beneficial uses.

5.2.5. In groundwaters used for domestic or municipal supply (MUN), the collection, treatment, storage, and disposal of wastewater or use of recycled water shall not cause the median of the most probable number of coliform organisms over any 7-day period to exceed 1.1 MPN/100 mL or 1 colony/100 mL.

5.2.6. The collection, treatment, storage and use of wastewater or recycled water shall not cause groundwater to contain toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in humans, or that adversely affects beneficial uses. This limitation applies regardless of whether the toxicity is caused by a single substance or the synergistic effect of multiple substances.

6. PROVISIONS

6.1. Standard Provisions.

6.1.1. Federal Standard Provisions. The Permittee shall comply with all Standard Provisions included in Attachment D of this Order.

6.1.2. Regional Water Board Standard Provisions. The Permittee shall comply with the following provisions. In the event that there is any conflict, duplication, or overlap between provisions specified by this Order, the more stringent provision shall apply:

6.1.2.1. Failure to comply with provisions or requirements of this Order, or violation of other applicable laws or regulations governing discharges from this facility, may subject the Permittee to administrative or civil liabilities, criminal penalties, and/or other enforcement remedies to ensure compliance.

Additionally, certain violations may subject the Permittee to civil or criminal enforcement from appropriate local, state, or federal law enforcement entities.

6.1.2.2. In the event the Permittee does not comply or will be unable to comply for any reason, with any prohibition, final effluent limitation, recycling specification, other specification, receiving water limitation, or provision of this Order that may result in a significant threat to human health or to the environment, such as inundation of treatment components, breach of pond containment, recycled water main break or equivalent release, irrigation runoff, etc., that results in a discharge to a drainage channel or a surface water, the Permittee shall:

6.1.2.2.1. Notify Regional Water Board staff within 24 hours of having knowledge of such noncompliance. Spill notification and reporting shall be conducted in accordance with Section 5.5 of Attachment D and 10.6 of the Monitoring and Reporting Program (Attachment E).

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6.1.2.2.2. Investigate the cause(s) of final effluent limitation and discharge specification exceedances and failures to comply with any prohibition, specification, or provision of this Order that may result in significant threat to human health or the environment.

6.1.2.2.3. Identify and implement corrective actions to prevent future exceedances or failures to comply with Order requirements.

6.1.2.2.4. Report the results of such investigations and corrective actions implemented in the monthly self-monitoring report (SMR) as required by MRP section 10.3.6.2.5 and 10.3.6.2.6.

6.2. Monitoring and Reporting Program (MRP) Requirements The Permittee shall comply with the MRP, included as Attachment E to this Order, and future revisions thereto.

6.3. Special Provisions

6.3.1. Reopener Provisions

6.3.1.1. Standard Revisions. If applicable water quality standards are promulgated or approved pursuant to Section 303 of the CWA, or amendments thereto, the Regional Water Board may reopen this Order and make modifications in accordance with such revised standards.

6.3.1.2. Reasonable Potential. This Order may be reopened for modification to include an effluent limitation, if monitoring establishes that the discharge causes, or has the reasonable potential to cause or contribute to, an excursion above a water quality criterion or objective applicable to the receiving water.

6.3.1.3. Whole Effluent Toxicity. As a result of a Toxicity Reduction Evaluation (TRE), this Order may be reopened to include a new chronic toxicity limitation, acute toxicity limitation and/or a limitation for a specific toxicant identified in the TRE.

6.3.1.4. 303(d)-Listed Pollutants. If an applicable total maximum daily load (TMDL) (see Fact Sheet, section 3.4) program is adopted, this Order may be reopened and effluent limitations for the pollutant(s) that are the subject of the TMDL modified or imposed to conform this Order to the TMDL requirements.

6.3.2. Best Management Practices and Pollution Prevention

6.3.2.1. Pollutant Minimization Program
The Permittee shall, as required by the Regional Water Board Executive Officer (hereafter Executive Officer), develop and conduct a PMP, as further CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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described below, when there is evidence (e.g., sample results from analytical methods more sensitive than those methods required by this Order, presence of whole effluent toxicity, health advisories for fish consumption, results of benthic or aquatic organism tissue sampling) that a priority pollutant is present in the effluent above an effluent limitation and either:

6.3.2.1.1. The concentration of the pollutant is reported as “Detected, but Not Quantified” (DNQ) and the effluent limitation is less than the reported ML;

6.3.2.1.2. The concentration of the pollutant is reported as non-detect (ND) and the effluent limitation is less than the MDL, using definitions described in Attachment A and reporting protocols described in MRP section 10.3.5.

6.3.2.2. The PMP shall include, but not be limited to, the following actions and submittals acceptable to the Regional Water Board:

6.3.2.2.1. An annual review and semi-annual monitoring of potential sources of the reportable pollutant(s), which may include fish tissue monitoring and other bio-uptake sampling;

6.3.2.2.2. Quarterly monitoring for the reportable pollutant(s) in the influent to the wastewater treatment system;

6.3.2.2.3. Submittal of a control strategy designed to proceed toward the goal of maintaining concentrations of the reportable pollutant(s) in the effluent at or below the effluent limitation;

6.3.2.2.4. Implementation of appropriate cost-effective control measures for the reportable pollutant(s), consistent with the control strategy; and

6.3.2.2.5. An annual status report that shall be submitted as part of the Annual Facility Report, due March 1st, to the Regional Water Board including:

6.3.2.2.5.1. All PMP monitoring results for the previous year;

6.3.2.2.5.2. A list of potential sources of the reportable pollutant(s);

6.3.2.2.5.3. A summary of all actions undertaken pursuant to the control strategy; and

6.3.2.2.5.4. A description of actions to be taken in the following year.

6.3.3. Construction, Operation and Maintenance Specifications

6.3.3.1. Proper Operation and Maintenance. This Order (Attachment D, Standard Provision 1.4) requires that the Permittee at all times properly operate and maintain all facilities and systems of treatment and control (and related appurtenances) that are installed or used by the Permittee to achieve compliance with this Order. Proper operation and maintenance includes CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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adequate laboratory quality control and appropriate quality assurance procedures.

6.3.3.2. Operation and Maintenance Manual. The Permittee shall maintain an updated Operation and Maintenance (O&M) Manual for the operational components of the Facility. The Permittee shall update the O&M Manual, as necessary, to conform to changes in operation and maintenance of the Facility. The Permittee shall operate and maintain the Facility in accordance with the most recently updated O&M Manual. The O&M Manual shall be readily available to operating personnel onsite and for review by state or federal inspectors. The O&M Manual shall include the following.

6.3.3.2.1. Description of the Facility’s organizational structure showing the number of employees, duties and qualifications and plant attendance schedules (daily, weekends and holidays, part-time, etc.). The description should include documentation that the personnel are knowledgeable and qualified to operate the Facility so as to achieve the required level of treatment at all times.

6.3.3.2.2. Detailed description of safe and effective operation and maintenance of treatment processes, process control instrumentation and equipment.

6.3.3.2.3. Description of laboratory and quality assurance procedures.

6.3.3.2.4. Inspection and essential maintenance schedules for all processes and equipment.

6.3.3.2.5. Description of safeguards to assure that, should there be reduction, loss, or failure of electric power, the Permittee will be able to comply with requirements of this Order.

6.3.3.2.6. Description of preventive (fail-safe) and contingency (response and cleanup) plans for controlling accidental discharges, and for minimizing the effect of such events. These plans shall identify the possible sources (such as loading and storage areas, power outage, waste treatment unit failure, process equipment failure, tank and piping failure) of accidental discharges, untreated or partially treated waste bypass, and polluted drainage.

6.3.3.3. Operating Records. The Permittee shall maintain operating records at the Facility or at the Permittee’s central depository. The records shall include: all analyses specified in the reclamation criteria; any documentation of operational problems, plant and equipment breakdowns, and diversions to emergency storage or disposal; and documentation of all corrective or preventive actions taken

6.3.3.4. Septage Handling Requirements
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6.3.3.4.1. Septage Management Plan. Prior to accepting septage, the Permittee shall submit a Septage Management Plan for approval by the Regional Water Board Executive Officer. The Septage Management Plan shall include a description of the proposed septage receiving station and how septage would be handled, identify the necessary legal authorities to monitor and enforce septage handling requirements, specify standard operating procedures (SOPs) for accepting septage, and demonstrate that the Facility has the capability of handling the septage without violating any conditions of this Order.

6.3.3.4.2. Septage Handling Specifications. The Permittee may accept septage upon written notification of approval of the Septage Management Plan by the Regional Water Board Executive Officer. The Permittee shall comply with the following specifications for accepting septage:

6.3.3.4.2.1. The Permittee shall implement any necessary legal authorities to monitor and enforce septage handling requirements, including restriction of discharges of toxic materials to the collection system and wastewater treatment facility and inspection facilities connected to the system.

6.3.3.4.2.2. The Permittee shall maintain a waste hauler manifest that identifies the name of the hauler, county identification number, the date and time the waste load was transferred, and the volume and source of the waste.

6.3.3.4.2.3. The Permittee shall accept the discharge of septage only during business hours and when the Permittee’s operations staff is on site.

6.3.3.4.2.4. The Permittee shall accept septage only at an approved septage receiving station/location.

6.3.3.4.2.5. The Permittee shall collect representative grab samples of septage loads in accordance with the MRP (Attachment E).

6.3.4. Special Provisions for Publicly-Owned Treatment Works (POTWs)

6.3.4.1. Pretreatment of Industrial Waste

6.3.4.1.1. The Permittee shall be responsible for the performance of all pretreatment requirements contained in 40 C.F.R. part 403 and shall be subject to enforcement actions, penalties, fines, and other remedies by the U.S. EPA or other appropriate parties as provided in the CWA, as amended (33 USC 1351 et seq.). The Permittee shall implement and enforce its approved Facility Pretreatment Program. The Permittee’s approved Facility Pretreatment Program is hereby made an enforceable condition of this Order. U.S. EPA may initiate enforcement action against an industrial user for noncompliance with applicable standards and requirements as provided in the CWA.

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6.3.4.1.2. The Permittee shall enforce the requirements promulgated under Sections 307(b), 307(c), 307(d), and 402(d) of the CWA. The Permittee shall cause industrial users subject to Federal Categorical Standards to achieve compliance no later than the date specified in those requirements or, in the case of a new industrial user, upon commencement of the discharge.

6.3.4.1.3. The Permittee shall perform the pretreatment functions as required in 40 C.F.R. part 403 including, but not limited to:

6.3.4.1.3.1. Implement the necessary legal authorities as provided in 40 C.F.R. section 403.8(f)(1);

6.3.4.1.3.2. Enforce the pretreatment requirements under 40 C.F.R. sections 403.5 and 403.6;

6.3.4.1.3.3. Implement the programmatic functions as provided in 40 C.F.R. section 403.8(f)(2); and

6.3.4.1.3.4. Provide the requisite funding and personnel to implement the pretreatment program as provided in 40 C.F.R. section 403.8(f)(3).

6.3.4.1.4. The Permittee shall implement, as more completely set forth in 40 C.F.R. section 403.5, the necessary legal authorities, programs, and controls to ensure that the following incompatible wastes are not introduced to the treatment system:

6.3.4.1.4.1. Wastes which create a fire or explosion hazard in the treatment works;

6.3.4.1.4.2. Wastes which will cause corrosive structural damage to treatment works, but in no case wastes with a pH lower than 5.0, unless the works is specially designed to accommodate such wastes;

6.3.4.1.4.3. Solid or viscous wastes in amounts which cause obstruction to flow in sewers, or which cause other interference with proper operation of treatment works;

6.3.4.1.4.4. Any waste, including oxygen demanding pollutants (BOD5, etc.), released in such volume or strength as to cause inhibition or disruption in the treatment works, and subsequent treatment process upset and loss of treatment efficiency;

6.3.4.1.4.5. Heat in amounts that inhibit or disrupt biological activity in the treatment works, or that raise influent temperatures above 40°C (104°F);

6.3.4.1.4.6. Petroleum oil, non-biodegradable cutting oil, or products of mineral oil origin in amounts that will cause interference or pass through; CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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6.3.4.1.4.7. Pollutants which result in the presence of toxic gases, vapors, or fumes within the treatment works in a quantity that may cause acute worker health and safety problems; and

6.3.4.1.4.8. Any trucked or hauled pollutants, except at points predesignated by the Permittee, and consisting of waste that can be adequately treated at the Facility.

6.3.4.1.5. The Permittee shall implement, as more completely set forth in 40 C.F.R. section 403.5, the legal authorities, programs, and controls necessary to ensure that indirect discharges do not introduce pollutants into the sewerage system that, either alone or in conjunction with a discharge or discharges from other sources:

6.3.4.1.5.1. Flow through the system to the receiving water in quantities or concentrations that cause a violation of this Order, or

6.3.4.1.5.2. Inhibit or disrupt treatment processes, treatment system operations, or sludge processes, use, or disposal and either cause a violation of this Order or prevent sludge use or disposal in accordance with this Order.

6.3.4.2. Sludge Disposal and Handling Requirements

6.3.4.2.1. Sludge, as used in this Order, means the solid, semisolid, and liquid residues removed during primary, secondary, or advanced wastewater treatment processes. Solid waste refers to grit and screenings generated during preliminary treatment. Biosolids refers to sludge that has been treated, tested, and demonstrated to be capable of being beneficially and legally used pursuant to federal and state regulations as a soil amendment for agriculture, silviculture, horticulture, and land reclamation activities.

6.3.4.2.2. All collected sludge and other solid waste removed from liquid wastes shall be removed from screens, sumps, ponds, and tanks as needed to ensure optimal plant operation and disposed of in accordance with applicable federal and state regulations.

6.3.4.2.3. The use and disposal of biosolids shall comply with all of the land application and disposal requirements in 40 C.F.R. part 503, which are enforceable by the U.S. EPA, not the Regional Water Board. If during the life of this Order, the state accepts primacy for implementation of 40 C.F.R. part 503, the Regional Water Board may also initiate enforcement where appropriate.

6.3.4.2.4. Sludge or biosolids that are disposed of in a municipal solid waste landfill or used as daily landfill cover shall meet the applicable requirements of 40 C.F.R. part 258. In the annual self-monitoring report, the Permittee shall report the amount of sludge placed in a landfill and the landfill(s) which received the sludge or biosolids.

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6.3.4.2.5. The Permittee shall take all reasonable steps to prevent and minimize any sludge use or disposal in violation of this Order that may adversely affect human health or the environment.

6.3.4.2.6. Solids and sludge treatment, storage, and disposal or reuse shall not create a nuisance, such as objectionable odors or flies, and shall not result in groundwater contamination.

6.3.4.2.7. Solids and sludge treatment and storage sites shall have facilities adequate to divert surface water runoff from adjacent areas, to protect the boundaries of the site from erosion, and to prevent drainage from the treatment and storage site. Adequate protection is defined as protection from a design storm with a 100-year recurrence interval and 24-hour duration.

6.3.4.2.8. The discharge of sewage sludge and solids shall not cause waste material to be in a position where it is, or can be, conveyed from the treatment and storage sites and deposited in the waters of the state.

6.3.4.2.9. For the land application of biosolids as soil amendment, the Permittee shall submit a report of waste discharge or the Permittee may dispose of biosolids at another appropriately permitted facility.

6.3.4.2.10. New sludge treatment and storage facilities must comply with the requirements of title 27 of the CCR for the protection of water quality.

6.3.4.3. Wastewater Collection System
The Permittee has coverage under, and is separately subject to, the requirements of State Water Board Order No. WQ 2022-0103-DWQ, Statewide Waste Discharge Requirements General Order for Sanitary Sewer Systems. As such, the Permittee provides notification and reporting of SSOs in accordance with the requirements of Order No. WQ 2022-0103-DWQ and any revisions thereto for operation of its wastewater collection system.

6.3.4.4. Operator Certification
Supervisors and operators of municipal wastewater treatment facilities shall possess a certificate of appropriate grade in accordance with CCR title 23 of the CCR, section 3680. The State Water Board may accept experience in lieu of qualification training. In lieu of a properly certified wastewater treatment facility operator, the State Water Board may approve use of a water treatment facility operator of appropriate grade certified by DDW where water recycling is involved.

6.3.4.5. Ensuring Adequate Capacity
If the Facility will reach capacity within 4 years, the Permittee shall notify the Regional Water Board. A copy of such notification shall be sent to appropriate CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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local elected officials, local permitting agencies, and the press. Factors to be evaluated in assessing reserve capacity shall include, at a minimum, (1) comparison of the wet weather design flow with the highest daily flow, and (2) comparison of the average dry weather design flow with the lowest 30-day flow. The Permittee shall demonstrate that adequate steps are being taken to address the capacity problem. The Permittee shall submit a technical report the Regional Water Board showing how flow volumes will be prevented from exceeding capacity, or how capacity will be increased, within 120 days after providing notification to the Regional Water Board, or within 120 days after receipt of Regional Water Board notification that the Facility will reach capacity within 4 years. The time for filing the required technical report may be extended by the Regional Water Board. An extension of 30 days may be granted by the Executive Officer, and longer extensions may be granted by the Regional Water Board itself. [Cal. Code. Regs., tit. 23, §2232].

6.3.5. Other Special Provisions

6.3.5.1. Storm Water
For the control of storm water discharges from the Facility, if required, the Permittee shall seek separate authorization to discharge under the requirements of the State Water Board’s Water Quality Order No. 2014-0057- DWQ, NPDES General Permit No. CAS000001, General Permit for Storm Water Discharges Associated with Industrial Activities (or subsequent renewed versions of the NPDES General Permit CAS000001), which is not incorporated by reference in this Order.

BMPs to control the run-on of storm water to the Facility site shall be maintained and upgraded as necessary. The Permittee shall describe the effectiveness of these storm water BMPs, as well as activities to maintain and upgrade these BMPs during the previous year, in its annual report to the Regional Water Board.

6.3.6. Compliance Schedules – Not Applicable
This Order does not establish interim effluent limitations or schedules of compliance for final numeric effluent limitations.

7. COMPLIANCE DETERMINATION
Compliance with the effluent limitations contained in section 4 of this Order and with Discharge Prohibition 3.7 will be determined as specified below.

7.1. Compliance with Effluent Limitations

7.1.1. Single Constituent Effluent Limitations. The Permittee is out of compliance with the effluent limitation if the concentration of the pollutant in the monitoring CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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sample is greater than the effluent limitation and greater than or equal to the reported Minimum Level (ML).

7.1.2. Effluent Limitations Expressed as a Sum of Several Constituents. The Permittee is out of compliance with an effluent limitation which applies to the sum of a group of chemicals (e.g., PCBs) if the sum of the individual pollutant concentrations is greater than the effluent limitation. Individual pollutants of the group will be considered to have a concentration of zero if the constituent is reported as non-detect (ND) or detected but not quantified (DNQ).

7.2. Multiple Sample Data
When determining compliance with an AMEL for priority pollutants, and more than one sample result is available, the Permittee shall compute the arithmetic mean unless the data set contains one or more reported determinations of “Detected, but Not Quantified” (DNQ) or “Not Detected” (ND). In those cases, the Permittee shall compute the median in place of the arithmetic mean in accordance with the following procedure.

7.2.1. The data set shall be ranked from low to high, ranking the reported ND determinations lowest, DNQ determinations next, followed by quantified values (if any). The order of the individual ND or DNQ determinations is unimportant.

7.2.2. The median value of the data set shall be determined. If the data set has an odd number of data points, then the median is the middle value. If the data set has an even number of data points, then the median is the average of the two middle values unless one or both of the points are ND or DNQ, in which case the median value shall be the lower of the two data points where DNQ is lower than a value and ND is lower than DNQ and a value of zero shall be used for the ND or DNQ value in the median calculation for compliance purposes only. Using a value of zero for DNQ or ND samples does not apply when performing reasonable potential or antidegradation analyses.

7.3. Average Monthly Effluent Limitation (AMEL)
If the average (or when applicable, the median determined by section 7.2 above for multiple sample data) of daily discharges over a calendar month exceeds the AMEL for a given parameter, this will represent a single violation, though the Permittee will be considered out of compliance for each day of that month for that parameter (e.g., resulting in 31 days of non-compliance in a 31-day month).

If only a single sample is taken during the calendar month and the analytical result for that sample exceeds the AMEL, the Permittee will be considered out of compliance for that calendar month. The Permittee will only be considered out of compliance for days when the discharge occurs. If there are ND or DNQ results for a specific constituent in a calendar month, the Permittee shall calculate the median of all sample results within that month for compliance determination with the AMEL as described in section 7.2, above.

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7.4. Average Weekly Effluent Limitation (AWEL)
If the average (or when applicable, the median determined by section 7.2 above for multiple sample data) of daily discharges over a calendar week (Sunday through Saturday) exceeds the AWEL for a given parameter, this will represent a single violation, though the Permittee will be considered out of compliance for each day of that week for that parameter, resulting in 7 days of non-compliance.

If only a single sample is taken during the calendar week and the analytical result for that sample exceeds the AWEL, the Permittee will be considered out of compliance for that calendar week. The Permittee will only be considered out of compliance for days when the discharge occurs. If there are ND or DNQ results for a specific constituent in a calendar week, the Permittee shall calculate the median of all sample results within that week for compliance determination with the AWEL as described in section 7.2, above.

7.5. Maximum Daily Effluent Limitation (MDEL)
If a daily discharge (or when applicable, the median determined by section 7.2, above, for multiple sample data of a daily discharge) exceeds the MDEL for a given parameter, the Permittee will be considered out of compliance for that parameter for that 1 day only within the reporting period.

7.6. Instantaneous Minimum Effluent Limitation
If the analytical result of a single grab sample is lower than the instantaneous minimum effluent limitation for a parameter, the Permittee will be considered out of compliance for that parameter for that single sample. Non-compliance for each sample will be considered separately (e.g., the results of two grab samples taken within a calendar day that both are lower than the instantaneous minimum effluent limitation would result in two instances of non-compliance with the instantaneous minimum effluent limitation).

If the Permittee monitors pH continuously, pursuant to 40 C.F.R. section 401.17, the Permittee shall be in compliance with the pH limitation specified herein provided that both of the following conditions are satisfied: (1) the total sum of time during which the pH values are outside the required range of pH values shall not exceed 7 hours and 26 minutes in any calendar month; and (2) no individual excursion from the range of pH values shall exceed 60 minutes.

7.7. Instantaneous Maximum Effluent Limitation
If the analytical result of a single grab sample is higher than the instantaneous maximum effluent limitation for a parameter, the Permittee will be considered out of compliance for that parameter for that single sample. Non-compliance for each sample will be considered separately (e.g., the results of two grab samples taken within a calendar day that both exceed the instantaneous maximum effluent CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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limitation would result in two instances of non-compliance with the instantaneous maximum effluent limitation).

7.8. Bacteriological Limitations (Fecal Coliform Bacteria, Enterococci, and Total Coliform Bacteria)

7.8.1. Median. The median is the central tendency concentration of the pollutant. The data set shall be ranked from low to high, ranking any ND concentrations lowest, followed by quantified values. The median value is determined based on the number of data points in the set. If the data set has an odd number of data points, then the median is the middle value. If the data set has an even number of data points, the median is the average of the two middle values, unless one or both points are ND or DNQ, in which case the median value shall be the lower of the two middle data points. DNQ is lower than a detected value, and ND is lower than DNQ.

7.8.2. Geometric Mean (GM). The geometric mean is a type of mean or average that indicates the central tendency or typical value of a set of numbers by using the product of their values (as opposed to the arithmetic mean which uses their sum). The geometric mean shall be calculated using the 5 most recent samples from a site using the following formula:

Where x is the sample value and n is the number of samples taken.

7.8.3. Six-week Rolling Geometric Mean. The rolling geometric mean shall be calculated using at least 5 sample results over a 6-week period from a site using the following formula:

Where x is the sample value and n is the number of samples taken.

7.8.4. Statistical Threshold Value. (1) The data set shall be ranked from low to high, ranking any ND concentrations lowest, followed by quantified values. (2) The number of sample results should then be multiplied by 90 percent then rounded CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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up to the nearest whole number. (3) Count the values in the data set starting from lowest to highest until the number indicated in step (2) is reached. (4) To be compliant with the statistical threshold value in Receiving Water Limitation

5.1.1.1.1.2, all sample results less than the point described in step 3 must be less than 100 MPN/100 mL.

7.9. Chronic Toxicity
Compliance with the accelerated monitoring and TRE provisions shall constitute compliance with the chronic toxicity requirements, all specified in the MRP (Attachment E, sections 5.1 and 5.2).

7.10. Average Dry Weather Flow
Compliance with the average dry weather flow prohibition in section 3.7 of this Order will be determined once each calendar year by evaluating all flow data collected in a calendar year. The flow through the facility, measured daily and averaged monthly, must be 1.86 mgd or less for the month with the lowest average monthly flow.

7.11. Peak Daily Wet Weather Flow
The peak daily wet weather flow is the maximum flow rate that occurs over a 24- hour period. Compliance with the peak daily wet weather flow prohibition in section

3.7 of this Order will be determined daily by measuring the daily average flow at Monitoring Location INF-001. If the measured daily average flow exceeds 6.12 mgd, the discharge is not in compliance with Prohibition 3.7 of this Order.

7.12. Chlorine Residual Effluent Limitations
Compliance with the chlorine residual effluent limitations shall be based on continuous residual monitoring at Monitoring Location EFF-001. The Permittee shall report from discrete readings of the continuous monitoring every hour on the hour. Compliance shall be based on an average of these discrete hourly readings on a daily basis. The Permittee shall retain continuous monitoring readings for at least three years. The Regional Water Board retains the right to use all continuous monitoring data for discretionary enforcement.

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DEFINITIONS

AREAS OF SPECIAL BIOLOGICAL SIGNIFICANCE (ASBS)
Those areas designated by the State Water Resources Control Board (State Water Board) as ocean areas requiring protection of species or biological communities to the extent that alteration of natural water quality is undesirable. All Areas of Special Biological Significance are also classified as a subset of STATE WATER QUALITY PROTECTION AREAS.

ARITHMETIC MEAN (µ)
Also called the average, is the sum of measured values divided by the number of samples. For ambient water concentrations, the arithmetic mean is calculated as follows:
where: Σx is the sum of the measured ambient water concentrations, and n is the number of samples.

AVERAGE MONTHLY EFFLUENT LIMITATION (AMEL)
The highest allowable average of daily discharges over a calendar month, calculated as the sum of all daily discharges measured during a calendar month divided by the number of daily discharges measured during that month.

AVERAGE WEEKLY EFFLUENT LIMITATION (AWEL)
The highest allowable average of daily discharges over a calendar week (Sunday through Saturday), calculated as the sum of all daily discharges measured during a calendar week divided by the number of daily discharges measured during that week.

CHLORDANE
Shall mean the sum of chlordane-alpha, chlordane-gamma, chlordene-alpha, chlordene-gamma, nonachlor-alpha, nonachlor-gamma, and oxychlordane.

COEFFICIENT OF VARIATION (CV)
CV is a measure of the data variability and is calculated as the estimated standard deviation divided by the arithmetic mean of the observed values.

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CHRONIC TOXICITY
This parameter shall be used to measure the acceptability of waters for supporting a healthy marine biota until improved methods are developed to evaluate biological response. See also Test of Significant Toxicity.

DAILY DISCHARGE
Daily Discharge is defined as either: (1) the total mass of the constituent discharged over the calendar day (12:00 am through 11:59 pm) or any 24-hour period that reasonably represents a calendar day for purposes of sampling (as specified in the permit), for a constituent with limitations expressed in units of mass or; (2) the unweighted arithmetic mean measurement of the constituent over the day for a constituent with limitations expressed in other units of measurement (e.g., concentration).

The daily discharge may be determined by the analytical results of a composite sample taken over the course of one day (a calendar day or other 24-hour period defined as a day) or by the arithmetic mean of analytical results from one or more grab samples taken over the course of the day.

For composite sampling, if 1 day is defined as a 24-hour period other than a calendar day, the analytical result for the 24-hour period will be considered as the result for the calendar day in which the 24-hour period ends.

DDT
Shall mean the sum of 4,4’DDT, 2,4’DDT, 4,4’DDE, 2,4’DDE, 4,4’DDD, and 2,4’DDD.

DEGRADE
Degradation shall be determined by comparison of the waste field and reference site(s) for characteristic species diversity, population density, contamination, growth anomalies, debility, or supplanting of normal species by undesirable plant and animal species. Degradation occurs if there are significant differences in any of three major biotic groups, namely, demersal fish, benthic invertebrates, or attached algae. Other groups may be evaluated where benthic species are not affected, or are not the only ones affected.

DETECTED, BUT NOT QUANTIFIED (DNQ)
Sample results that are less than the reported Minimum Level, but greater than or equal to the laboratory’s MDL. Sample results reported as DNQ are estimated concentrations.

DICHLOROBENZENES
Shall mean the sum of 1,2- and 1,3-dichlorobenzene.

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DILUTION CREDIT
Dilution Credit is the amount of dilution granted to a discharge in the calculation of a water quality-based effluent limitation, based on the allowance of a specified mixing zone. It is calculated from the dilution ratio or determined through conducting a mixing zone study or modeling of the discharge and receiving water.

DOWNSTREAM OCEAN WATERS
Waters downstream with respect to ocean currents.

DREDGED MATERIAL
Any material excavated or dredged from the navigable waters of the United States, including material otherwise referred to as “spoil.”

EFFLUENT CONCENTRATION ALLOWANCE (ECA)
ECA is a value derived from the water quality criterion/objective, dilution credit, and ambient background concentration that is used, in conjunction with the coefficient of variation for the effluent monitoring data, to calculate a long-term average (LTA) discharge concentration. The ECA has the same meaning as wasteload allocation (WLA) as used in U.S. EPA guidance (Technical Support Document For Water Qualitybased Toxics Control, March 1991, second printing, EPA/505/2-90-001).

ENCLOSED BAYS
Indentations along the coast that enclose an area of oceanic water within distinct headlands or harbor works. Enclosed bays include all bays where the narrowest distance between headlands or outermost harbor works is less than 75 percent of the greatest dimension of the enclosed portion of the bay. This definition includes but is not limited to: Humboldt Bay, Bodega Harbor, Tomales Bay, Drakes Estero, San Francisco Bay, Morro Bay, Los Angeles Harbor, Upper and Lower Newport Bay, Mission Bay, and San Diego Bay.

ENDOSULFAN
The sum of endosulfan-alpha and -beta and endosulfan sulfate.

ESTIMATED CHEMICAL CONCENTRATION
The estimated chemical concentration that results from the confirmed detection of the substance by the analytical method below the ML value.

ESTUARIES AND COASTAL LAGOONS
Estuaries and Coastal Lagoons are waters at the mouths of streams that serve as mixing zones for fresh and ocean waters during a major portion of the year. Mouths of CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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streams that are temporarily separated from the ocean by sandbars shall be considered as estuaries. Estuarine waters will generally be considered to extend from a bay or the open ocean to the upstream limit of tidal action but may be considered to extend seaward if significant mixing of fresh and salt water occurs in the open coastal waters.

The waters described by this definition include but are not limited to the SacramentoSan Joaquin Delta as defined by Section 12220 of the California Water Code, Suisun Bay, Carquinez Strait downstream to Carquinez Bridge, and appropriate areas of the Smith, Klamath, Mad, Eel, Noyo, and Russian Rivers.

GEOMETRIC MEAN
The geometric mean is a type of mean or average that indicates the central tendency or typical value of a set of numbers by using the product of their values (as opposed to the arithmetic mean which uses their sum). The geometric mean is defined as the nth root of the product of n numbers. The formula is expressed as:

Where:
x is the sample value and n is the number of samples taken.

HALOMETHANES
Halomethanes shall mean the sum of bromoform, bromomethane (methyl bromide) and chloromethane (methyl chloride).

HCH
HCH shall mean the sum of the alpha, beta, gamma (lindane) and delta isomers of hexachlorocyclohexane.

INITIAL DILUTION
The process that results in the rapid and irreversible turbulent mixing of wastewater with ocean water around the point of discharge.

For a submerged buoyant discharge, characteristic of most municipal and industrial wastes that are released from the submarine outfalls, the momentum of the discharge and its initial buoyancy act together to produce turbulent mixing. Initial dilution in this case is completed when the diluting wastewater ceases to rise in the water column and first begins to spread horizontally.

For shallow water submerged discharges, surface discharges, and non-buoyant discharges, characteristic of cooling water wastes and some individual discharges, turbulent mixing results primarily from the momentum of discharge. Initial dilution, in CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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these cases, is considered to be completed when the momentum induced velocity of the discharge ceases to produce significant mixing of the waste, or the diluting plume reaches a fixed distance from the discharge to be specified by the Regional Water Board, whichever results in the lower estimate for initial dilution.

INSTANTANEOUS MAXIMUM EFFLUENT LIMITATION
The highest allowable value for any single grab sample or aliquot (i.e., each grab sample or aliquot is independently compared to the instantaneous maximum limitation).

INSTANTANEOUS MINIMUM EFFLUENT LIMITATION
The lowest allowable value for any single grab sample or aliquot (i.e., each grab sample or aliquot is independently compared to the instantaneous minimum limitation).

INSTREAM WASTE CONCENTRATION (IWC)
The concentration of a toxicant or effluent in the receiving water after mixing (the inverse of the dilution factor).

KELP BEDS
For purposes of the bacteriological standards of the Ocean Plan, are significant aggregations of marine algae of the genera Macrocystis and Nereocystis. Kelp beds include the total foliage canopy of Macrocystis and Nereocystis plants throughout the water column.

MARICULTURE
The culture of plants and animals in marine waters independent of any pollution source.

MATERIAL
(a) In common usage: (1) the substance or substances of which a thing is made or composed (2) substantial; (b) For purposes of the Ocean Plan relating to waste disposal, dredging and the disposal of dredged material and fill, MATERIAL means matter of any kind or description which is subject to regulation as waste, or any material dredged from the navigable waters of the United States. See also, DREDGED MATERIAL.

MAXIMUM DAILY EFFLUENT LIMITATION (MDEL)
The highest allowable daily discharge of a pollutant.

MEDIAN
The middle measurement in a set of data. After the measurements are ranked in order, the median is the middle measurement if the number of measurements is odd. If the CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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number of measurements is even, then the median is the arithmetic mean of the middle pair of ranked measurements.

METHOD DETECTION LIMIT (MDL)
The minimum concentration of a substance that can be reported with 99 percent confidence that the measured concentration is distinguishable from method blank results, as defined in 40 C.F.R. part 136, Attachment B.

MINIMUM LEVEL (ML)
The concentration at which the entire analytical system must give a recognizable signal and acceptable calibration point. The ML is the concentration in a sample that is equivalent to the concentration of the lowest calibration standard analyzed by a specific analytical procedure, assuming that all the method specified sample weights, volumes, and processing steps have been followed.

MIXING ZONE
Mixing Zone is a limited volume of receiving water that is allocated for mixing with a wastewater discharge where water quality criteria can be exceeded without causing adverse effects to the overall water body.

NATURAL LIGHT
Reduction of natural light may be determined by the Regional Water Board by measurement of light transmissivity or total irradiance, or both, according to the monitoring needs of the Regional Water Board.

NOT DETECTED (ND)
Those sample results less than the laboratory’s MDL.

OCEAN WATERS
The territorial marine waters of the state as defined by California law to the extent these waters are outside of enclosed bays, estuaries, and coastal lagoons. If a discharge outside the territorial waters of the state could affect the quality of the waters of the state, the discharge may be regulated to assure no violation of the Ocean Plan will occur in ocean waters.

PAHS (POLYNUCLEAR AROMATIC HYDROCARBONS)
The sum of acenaphthylene, anthracene, 1,2-benzanthracene, 3,4 benzofluoranthene, benzo[k]fluoranthene, 1,12-benzoperylene, benzo[a]pyrene, chrysene, dibenzo[ah]anthracene, fluorene, indeno[1,2,3-cd]pyrene, phenanthrene and pyrene.

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PCBS (POLYCHLORINATED BIPHENYLS)
The sum of chlorinated biphenyls whose analytical characteristics resemble those of Aroclor-1016, Aroclor-1221, Aroclor-1232, Aroclor-1242, Aroclor-1248, Aroclor-1254 and Aroclor-1260.

POLLUTANT MINIMIZATION PROGRAM (PMP)
PMP means waste minimization and pollution prevention actions that include, but are not limited to, product substitution, waste stream recycling, alternative waste management methods, and education of the public and businesses. The goal of the PMP shall be to reduce all potential sources of Ocean Plan Table 1 pollutants through pollutant minimization (control) strategies, including pollution prevention measures as appropriate, to maintain the effluent concentration at or below the water quality-based effluent limitation. Pollution prevention measures may be particularly appropriate for persistent bioaccumulative priority pollutants where there is evidence that beneficial uses are being impacted. The Regional Water Board may consider cost effectiveness when establishing the requirements of a PMP. The completion and implementation of a Pollution Prevention Plan, if required pursuant to Water Code section 13263.3(d), shall be considered to fulfill the PMP requirements.

POLLUTION PREVENTION
Pollution Prevention means any action that causes a net reduction in the use or generation of a hazardous substance or other pollutant that is discharged into water and includes, but is not limited to, input change, operational improvement, production process change, and product reformulation (as defined in Water Code section 13263.3).

Pollution prevention does not include actions that merely shift a pollutant in wastewater from one environmental medium to another environmental medium, unless clear environmental benefits of such an approach are identified to the satisfaction of the State Water Resources Control Board (State Water Board) or Regional Water Board.

PUBLICLY OWNED TREATMENT WORKS (POTW)
Pollution A treatment works as defined in section 212 of the Clean Water Act (CWA), which is owned by a government agency as defined by section 502(4) of the CWA.

Section 502(4) of the CWA defines a municipality as a city, town, borough, county, parish, district, association, or other public body created by or pursuant to state law and having jurisdiction over disposal of sewage, industrial wastes, or other wastes. This definition includes any devices and systems used in the storage, treatment, recycling, and recycling of municipal sewage or industrial wastes of a liquid nature. It also includes sewers, pipes and other conveyances only if they convey wastewater to a POTW Treatment Plant. The term also means the municipality as defined in section 502(4) of the CWA, which has jurisdiction over the Indirect Discharges to and the discharges from such a treatment works.

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RECYCLED WATER
Water which, as a result of treatment of municipal wastewater, is suitable for a direct beneficial use or a controlled use that would not otherwise occur and is therefore considered a valuable resource (Water Code section 13050). The terms “recycled water” and “reclaimed water” have the same meaning (Water Code section 26).

REPORTED MINIMUM LEVEL
The reported ML (also known as the Reporting Level or RL) is the ML (and its associated analytical method) chosen by the Permittee for reporting and compliance determination from the MLs included in this Order, including an additional factor if applicable as discussed herein. The MLs included in this Order correspond to approved analytical methods for reporting a sample result that are selected by the Regional Water Board either from Appendix II of the Ocean Plan in accordance with section III.C.5.a. of the Ocean Plan or established in accordance with section III.C.5.b. of the Ocean Plan.

The ML is based on the proper application of method-based analytical procedures for sample preparation and the absence of any matrix interferences. Other factors may be applied to the ML depending on the specific sample preparation steps employed. For example, the treatment typically applied in cases where there are matrix-effects is to dilute the sample or sample aliquot by a factor of ten. In such cases, this additional factor must be applied to the ML in the computation of the reported ML.

SATELLITE COLLECTION SYSTEM
The portion, if any, of a sanitary sewer system owned or operated by a different public agency than the agency that owns and operates the wastewater treatment facility that a sanitary sewer system is tributary to.

SHELLFISH
Organisms identified by the California Department of Health Services as shellfish for public health purposes (i.e., mussels, clams and oysters).

SIGNIFICANT DIFFERENCE
Defined as a statistically significant difference in the means of two distributions of sampling results at the 95 percent confidence level.

SIX-MONTH MEDIAN EFFLUENT LIMITATION
The highest allowable moving median of all daily discharges for any 180-day period.

STATE WATER QUALITY PROTECTION AREAS (SWQPAS)
Non-terrestrial marine or estuarine areas designated to protect marine species or biological communities from an undesirable alteration in natural water quality. All AREAS OF SPECIAL BIOLOGICAL SIGNIFICANCE (ASBS) that were previously CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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designated by the State Water Board in Resolutions 74-28, 74-32, and 75-61 are now also classified as a subset of State Water Quality Protection Areas and require special protections afforded by the Ocean Plan.

TCDD EQUIVALENTS
The sum of the concentrations of chlorinated dibenzodioxins (2,3,7,8-CDDs) and chlorinated dibenzofurans (2,3,7,8-CDFs) multiplied by their respective toxicity factors, as shown in the table below.

Isomer Group Toxicity
Equivalence Factor
2,3,7,8-tetra CDD 1.0
2,3,7,8-penta CDD 0.5
2,3,7,8-hexa CDDs 0.1
2,3,7,8-hepta CDD 0.01
octa CDD 0.001
2,3,7,8 tetra CDF 0.1
1,2,3,7,8 penta CDF 0.05
2,3,4,7,8 penta CDF 0.5
2,3,7,8 hexa CDFs 0.1
2,3,7,8 hepta CDFs 0.01
octa CDF 0.001

TEST OF SIGNIFICANT TOXICITY (TST)
The statistical approach described in National Pollutant Discharge Elimination System Test of Significant Toxicity Implementation Document (EPA 833-R10-003, 2010). TST was developed by the U.S. Environmental Protection Agency (EPA) for analyzing WET and ambient toxicity data. Using the TST approach, the sample is declared toxic if there is greater than or equal to a 25% effect in chronic tests, or if there is greater than or equal to a 20% effect in acute tests at the permitted instream waste concentration (IWC) (referred to as the toxic regulatory management decision (RMD)). The sample is declared non-toxic if there is less than or equal to a 10% effect at the IWC in acute or chronic tests (referred to as the non-toxic RMD).

TOXICITY REDUCTION EVALUATION (TRE)
A study conducted in a step-wise process designed to identify the causative agents of effluent or ambient toxicity, isolate the sources of toxicity, evaluate the effectiveness of toxicity control options, and then confirm the reduction in toxicity. The first steps of the TRE consist of the collection of data relevant to the toxicity, including additional toxicity CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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testing, and an evaluation of facility operations and maintenance practices, and best management practices. A Toxicity Identification Evaluation (TIE) may be required as part of the TRE, if appropriate. (A TIE is a set of procedures to identify the specific chemical(s) responsible for toxicity. These procedures are performed in three phases (characterization, identification, and confirmation) using aquatic organism toxicity tests.) WASTE
As used in the Ocean Plan, waste includes a Permittee’s total discharge, of whatever origin, i.e., gross, not net, discharge.

WATER RECYCLING
The treatment of wastewater to render it suitable for reuse, the transportation of treated wastewater to the place of use, and the actual use of treated wastewater for a direct beneficial use or controlled use that would not otherwise occur.

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MAP
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FLOW SCHEMATIC
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STANDARD PROVISIONS

1. STANDARD PROVISIONS – PERMIT COMPLIANCE

1.1. Duty to Comply

1.1.1. The Permittee must comply with all of the terms, requirements, and conditions of this Order. Any noncompliance constitutes a violation of the Clean Water Act (CWA) and the California Water Code and is grounds for enforcement action; permit termination, revocation and reissuance, or modification; denial of a permit renewal application; or a combination thereof. (40 C.F.R. § 122.41(a); Wat.

Code, §§ 13261, 13263, 13265, 13268, 13000, 13001, 13304, 13350, 13385.)

1.1.2. The Permittee shall comply with effluent standards or prohibitions established under Section 307(a) of the CWA for toxic pollutants within the time provided in the regulations that establish these standards or prohibitions, even if this Order has not yet been modified to incorporate the requirement. (40 C.F.R. § 122.41(a)(1).)

1.2. Need to Halt or Reduce Activity Not a Defense
It shall not be a defense for a Permittee in an enforcement action that it would have been necessary to halt or reduce the permitted activity in order to maintain compliance with the conditions of this Order. (40 C.F.R. § 122.41(c).)

1.3. Duty to Mitigate
The Permittee shall take all reasonable steps to minimize or prevent any discharge in violation of this Order that has a reasonable likelihood of adversely affecting human health or the environment. (40 C.F.R. § 122.41(d).)

1.4. Proper Operation and Maintenance
The Permittee shall at all times properly operate and maintain all facilities and systems of treatment and control (and related appurtenances) which are installed or used by the Permittee to achieve compliance with the conditions of this Order.

Proper operation and maintenance also includes adequate laboratory controls and appropriate quality assurance procedures. This provision requires the operation of backup or auxiliary facilities or similar systems that are installed by a Permittee only when necessary to achieve compliance with the conditions of this Order. (40 C.F.R. § 122.41(e).)

1.5. Property Rights

1.5.1. This Order does not convey any property rights of any sort or any exclusive privileges. (40 C.F.R. § 122.41(g).)
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1.5.2. The issuance of this Order does not authorize any injury to persons or property or invasion of other private rights, or any infringement of state or local law or regulations. (40 C.F.R. § 122.5(c).)

1.6. Inspection and Entry
The Permittee shall allow the Regional Water Board, State Water Board, U.S.

EPA, and/or their authorized representatives (including an authorized contractor acting as their representative), upon the presentation of credentials and other documents, as may be required by law, to (33 U.S.C. § 1318(a)(4)(B); 40 C.F.R. § 122.41(i); Wat. Code, §§ 13267, 13383):

1.6.1. Enter upon the Permittee's premises where a regulated facility or activity is located or conducted, or where records are kept under the conditions of this Order (33 U.S.C. § 1318(a)(4)(B)(i); 40 C.F.R. § 122.41(i)(1); Wat. Code, §§ 13267, 13383);

1.6.2. Have access to and copy, at reasonable times, any records that must be kept under the conditions of this Order (33 U.S.C. § 1318(a)(4)(B)(ii); 40 C.F.R. § 122.41(i)(2); Wat. Code, §§ 13267, 13383);

1.6.3. Inspect and photograph, at reasonable times, any facilities, equipment (including monitoring and control equipment), practices, or operations regulated or required under this Order (33 U.S.C. § 1318(a)(4)(B)(ii); 40 C.F.R. § 122.41(i)(3); Wat. Code, §§ 13267, 13383); and

1.6.4. Sample or monitor, at reasonable times, for the purposes of assuring Order compliance or as otherwise authorized by the CWA or the Water Code, any substances or parameters at any location. (33 U.S.C. § 1318(a)(4)(B); 40 C.F.R. § 122.41(i)(4); Wat. Code, §§ 13267, 13383.)

1.7. Bypass

1.7.1. Definitions

1.7.1.1. “Bypass” means the intentional diversion of waste streams from any portion of a treatment facility. (40 C.F.R. § 122.41(m)(1)(i).)

1.7.1.2. “Severe property damage” means substantial physical damage to property, damage to the treatment facilities, which causes them to become inoperable, or substantial and permanent loss of natural resources that can reasonably be expected to occur in the absence of a bypass. Severe property damage does not mean economic loss caused by delays in production. (40 C.F.R. § 122.41(m)(1)(ii).)

1.7.2. Bypass not exceeding limitations. The Permittee may allow any bypass to occur which does not cause exceedances of effluent limitations, but only if it is for essential maintenance to assure efficient operation. These bypasses are not CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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subject to the provisions listed in Standard Provisions – Permit Compliance

1.7.3, 1.7.4, and 1.7.5 below. (40 C.F.R. § 122.41(m)(2).)

1.7.3. Prohibition of bypass. Bypass is prohibited, and the Regional Water Board may take enforcement action against a Permittee for bypass, unless (40 C.F.R. § 122.41(m)(4)(i)):

1.7.3.1. Bypass was unavoidable to prevent loss of life, personal injury, or severe property damage (40 C.F.R. § 122.41(m)(4)(i)(A));

1.7.3.2. There were no feasible alternatives to the bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, or maintenance during normal periods of equipment downtime. This condition is not satisfied if adequate back up equipment should have been installed in the exercise of reasonable engineering judgment to prevent a bypass that occurred during normal periods of equipment downtime or preventive maintenance (40 C.F.R. § 122.41(m)(4)(i)(B)); and

1.7.3.3. The Permittee submitted notice to the Regional Water Board as required under Standard Provisions – Permit Compliance 1.7.6 below. (40 C.F.R. § 122.41(m)(4)(i)(C).)

1.7.4. Burden of Proof. In any enforcement proceeding, the permittee seeking to establish the bypass defense has the burden of proof.

1.7.5. The Regional Water Board may approve an anticipated bypass, after considering its adverse effects, if the Regional Water Board determines that it will meet the three conditions listed in Standard Provisions – Permit Compliance

1.7.3 above. (40 C.F.R. § 122.41(m)(4)(ii).)

1.7.6. Notice

1.7.6.1. Anticipated bypass. If the Permittee knows in advance of the need for a bypass, it shall submit prior notice, if possible at least 10 days before the date of the bypass. The notice shall be sent to the Regional Water Board. As of December 21, 2025 a notice shall be submitted electronically to the initial recipient defined in Standard Provisions – Reporting 5.10 below. Notices shall comply with 40 C.F.R. part 3, 40 C.F.R. section 122.22, and 40 C.F.R. part 127. (40 C.F.R. § 122.41(m)(3)(i).)

1.7.6.2. Unanticipated bypass. The Permittee shall submit a notice of an unanticipated bypass as required in Standard Provisions - Reporting 5.5 below (24-hour notice). The notice shall be sent to the Regional Water Board.

As of December 21, 2025, a notice shall be submitted electronically to the initial recipient defined in Standard Provisions – Reporting 5.10 below.

Notices shall comply with 40 C.F.R. part 3, 40 C.F.R. section 122.22, and 40 C.F.R. part 127. (40 C.F.R. § 122.41(m)(3)(ii).)
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1.8. Upset
Upset means an exceptional incident in which there is unintentional and temporary noncompliance with technology based permit effluent limitations because of factors beyond the reasonable control of the Permittee. An upset does not include noncompliance to the extent caused by operational error, improperly designed treatment facilities, inadequate treatment facilities, lack of preventive maintenance, or careless or improper operation. (40 C.F.R. § 122.41(n)(1).)

1.8.1. Effect of an upset. An upset constitutes an affirmative defense to an action brought for noncompliance with such technology based permit effluent limitations if the requirements of Standard Provisions – Permit Compliance 1.8.2 below are met. No determination made during administrative review of claims that noncompliance was caused by upset, and before an action for noncompliance, is final administrative action subject to judicial review. (40 C.F.R. § 122.41(n)(2).)

1.8.2. Conditions necessary for a demonstration of upset. A Permittee who wishes to establish the affirmative defense of upset shall demonstrate, through properly signed, contemporaneous operating logs or other relevant evidence that (40 C.F.R. § 122.41(n)(3)):

1.8.2.1. An upset occurred and that the Permittee can identify the cause(s) of the upset (40 C.F.R. § 122.41(n)(3)(i));

1.8.2.2. The permitted facility was, at the time, being properly operated (40 C.F.R. § 122.41(n)(3)(ii));

1.8.2.3. The Permittee submitted notice of the upset as required in Standard Provisions – Reporting 5.5.2.2 below (24-hour notice) (40 C.F.R. § 122.41(n)(3)(iii)); and

1.8.2.4. The Permittee complied with any remedial measures required under Standard Provisions – Permit Compliance 1.3 above. (40 C.F.R. § 122.41(n)(3)(iv).)

1.8.3. Burden of proof. In any enforcement proceeding, the Permittee seeking to establish the occurrence of an upset has the burden of proof. (40 C.F.R. § 122.41(n)(4).)

2. STANDARD PROVISIONS – PERMIT ACTION

2.1. General
This Order may be modified, revoked and reissued, or terminated for cause. The filing of a request by the Permittee for modification, revocation and reissuance, or termination, or a notification of planned changes or anticipated noncompliance does not stay any Order condition. (40 C.F.R. § 122.41(f).) CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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2.2. Duty to Reapply
If the Permittee wishes to continue an activity regulated by this Order after the expiration date of this Order, the Permittee must apply for and obtain a new permit. (40 C.F.R. § 122.41(b).)

2.3. Transfers
This Order is not transferable to any person except after notice to the Regional Water Board. The Regional Water Board may require modification or revocation and reissuance of the Order to change the name of the Permittee and incorporate such other requirements as may be necessary under the CWA and the Water Code. (40 C.F.R. §§ 122.41(l)(3), 122.61.)

3. STANDARD PROVISIONS – MONITORING

3.1. Samples and measurements taken for the purpose of monitoring shall be representative of the monitored activity. (40 C.F.R. § 122.41(j)(1).)

3.2. Monitoring must be conducted according to test procedures approved under 40 C.F.R. part 136 for the analyses of pollutants unless another method is required under 40 C.F.R. chapter 1, subchapter N. Monitoring must be conducted according to sufficiently sensitive test methods approved under 40 C.F.R. part 136 for the analysis of pollutants or pollutant parameters or as required under 40 C.F.R. chapter 1, subchapter N. For the purposes of this paragraph, a method is sufficiently sensitive when:

3.2.1. The method minimum level (ML) is at or below the level of the most stringent effluent limitation established in the permit for the measured pollutant or pollutant parameter, and either the method ML is at or below the level of the most stringent applicable water quality criterion for the measured pollutant or pollutant parameter or the method ML is above the applicable water quality criterion but the amount of the pollutant or pollutant parameter in the facility’s discharge is high enough that the method detects and quantifies the level of the pollutant or pollutant parameter in the discharge; or

3.2.2. The method has the lowest ML of the analytical methods approved under 40 C.F.R. part 136 or required under 40 C.F.R. chapter 1, subchapter N for the measured pollutant or pollutant parameter.

In the case of pollutants or pollutant parameters for which there are no approved methods under 40 C.F.R. part 136 or otherwise required under 40 C.F.R. chapter 1, subchapter N, monitoring must be conducted according to a test procedure specified in this Order for such pollutants or pollutant parameters. (40 C.F.R. §§ 122.21(e)(3),122.41(j)(4), 122.44(i)(1)(iv).) CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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4. STANDARD PROVISIONS – RECORDS

4.1. The Permittee shall retain records of all monitoring information, including all calibration and maintenance records and all original strip chart recordings for continuous monitoring instrumentation, copies of all reports required by this Order, and records of all data used to complete the application for this Order, for a period of at least three (3) years from the date of the sample, measurement, report or application. This period may be extended by request of the Regional Water Board Executive Officer at any time. (40 C.F.R. § 122.41(j)(2).)

4.2. Records of monitoring information shall include:

4.2.1. The date, exact place, and time of sampling or measurements (40 C.F.R. § 122.41(j)(3)(i));

4.2.2. The individual(s) who performed the sampling or measurements (40 C.F.R. § 122.41(j)(3)(ii));

4.2.3. The date(s) analyses were performed (40 C.F.R. § 122.41(j)(3)(iii));

4.2.4. The individual(s) who performed the analyses (40 C.F.R. § 122.41(j)(3)(iv));

4.2.5. The analytical techniques or methods used (40 C.F.R. § 122.41(j)(3)(v)); and

4.2.6. The results of such analyses. (40 C.F.R. § 122.41(j)(3)(vi).)

4.3. Claims of confidentiality for the following information will be denied (40 C.F.R. § 122.7(b)):

4.3.1. The name and address of any permit applicant or Permittee (40 C.F.R. § 122.7(b)(1)); and

4.3.2. Permit applications and attachments, permits and effluent data. (40 C.F.R. § 122.7(b)(2).)

5. STANDARD PROVISIONS – REPORTING

5.1. Duty to Provide Information
The Permittee shall furnish to the Regional Water Board, State Water Board, or U.S. EPA within a reasonable time, any information which the Regional Water Board, State Water Board, or U.S. EPA may request to determine whether cause exists for modifying, revoking and reissuing, or terminating this Order or to determine compliance with this Order. Upon request, the Permittee shall also furnish to the Regional Water Board, State Water Board, or U.S. EPA copies of records required to be kept by this Order. (40 C.F.R. § 122.41(h); Wat. Code, §§ 13267, 13383.)
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5.2. Signatory and Certification Requirements

5.2.1. All applications, reports, or information submitted to the Regional Water Board, State Water Board, and/or U.S. EPA shall be signed and certified in accordance with Standard Provisions – Reporting 5.2.2, 5.2.3, 5.2.4, 5.2.5, and 5.2.6 below. (40 C.F.R. § 122.41(k).)

5.2.2. All permit applications shall be signed by either a principal executive officer or ranking elected official. For purposes of this provision, a principal executive officer of a federal agency includes: (i) the chief executive officer of the agency, or (ii) a senior executive officer having responsibility for the overall operations of a principal geographic unit of the agency (e.g., Regional Administrators of U.S.

EPA). (40 C.F.R. § 122.22(a)(3).).

5.2.3. All reports required by this Order and other information requested by the Regional Water Board, State Water Board, or U.S. EPA shall be signed by a person described in Standard Provisions – Reporting 5.2.2 above, or by a duly authorized representative of that person. A person is a duly authorized representative only if:

5.2.3.1. The authorization is made in writing by a person described in Standard Provisions – Reporting 5.2.2 above (40 C.F.R. § 122.22(b)(1));

5.2.3.2. The authorization specifies either an individual or a position having responsibility for the overall operation of the regulated facility or activity such as the position of plant manager, operator of a well or a well field, superintendent, position of equivalent responsibility, or an individual or position having overall responsibility for environmental matters for the company. (A duly authorized representative may thus be either a named individual or any individual occupying a named position.) (40 C.F.R. § 122.22(b)(2)); and

5.2.3.3. The written authorization is submitted to the Regional Water Board and State Water Board. (40 C.F.R. § 122.22(b)(3).)

5.2.4. If an authorization under Standard Provisions – Reporting 5.2.3 above is no longer accurate because a different individual or position has responsibility for the overall operation of the facility, a new authorization satisfying the requirements of Standard Provisions – Reporting 5.2.3 above must be submitted to the Regional Water Board and State Water Board prior to or together with any reports, information, or applications, to be signed by an authorized representative. (40 C.F.R. § 122.22(c).)

5.2.5. Any person signing a document under Standard Provisions – Reporting 5.2.2 or

5.2.3 above shall make the following certification:
“I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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designed to assure that qualified personnel properly gather and evaluate the information submitted. Based on my inquiry of the person or persons who manage the system or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations.” (40 C.F.R. § 122.22(d).)

5.2.6. Any person providing the electronic signature for documents described in Standard Provisions – 5.2.1, 5.2.2, or 5.2.3 that are submitted electronically shall meet all relevant requirements of Standard Provisions – Reporting 5.2, and shall ensure that all relevant requirements of 40 C.F.R. part 3 (Cross-Media Electronic Reporting) and 40 C.F.R. part 127 (NPDES Electronic Reporting Requirements) are met for that submission. (40 C.F.R § 122.22(e).)

5.3. Monitoring Reports

5.3.1. Monitoring results shall be reported at the intervals specified in the Monitoring and Reporting Program (Attachment E) in this Order. (40 C.F.R. § 122.41(l)(4).)

5.3.2. Monitoring results must be reported on a Discharge Monitoring Report (DMR) form or forms provided or specified by the Regional Water Board or State Water Board. As of December 21, 2016, all reports and forms must be submitted electronically to the initial recipient defined in Standard Provisions – Reporting

5.10 and comply with 40 C.F.R. part 3, 40 C.F.R. section 122.22, and 40 C.F.R. part 127. (40 C.F.R. § 122.41(l)(4)(i).)

5.3.3. If the Permittee monitors any pollutant more frequently than required by this Order using test procedures approved under 40 C.F.R. part 136, or another method required for an industry-specific waste stream under 40 C.F.R. chapter 1, subchapter N, the results of such monitoring shall be included in the calculation and reporting of the data submitted in the DMR or reporting form specified by the Regional Water Board or State Water Board. (40 C.F.R. § 122.41(l)(4)(ii).)

5.3.4. Calculations for all limitations, which require averaging of measurements, shall utilize an arithmetic mean unless otherwise specified in this Order. (40 C.F.R. § 122.41(l)(4)(iii).)

5.4. Compliance Schedules
Reports of compliance or noncompliance with, or any progress reports on, interim and final requirements contained in any compliance schedule of this Order, shall be submitted no later than 14 days following each schedule date. (40 C.F.R. § 122.41(l)(5).)
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5.5. Twenty-Four Hour Reporting

5.5.1. The Permittee shall report any noncompliance which may endanger health or the environment. Any information shall be provided orally within 24 hours from the time the Permittee becomes aware of the circumstances. A report shall also be provided within five (5) days of the time the Permittee becomes aware of the circumstances. The report shall contain a description of the noncompliance and its cause; the period of noncompliance, including exact dates and times, and if the noncompliance has not been corrected, the anticipated time it is expected to continue; and steps taken or planned to reduce, eliminate, and prevent reoccurrence of the noncompliance.

For noncompliance events related to combined sewer overflows, sanitary sewer overflows, or bypass events, these reports must include the data described above (with the exception of time of discovery) as well as the type of event (i.e., combined sewer overflow, sanitary sewer overflow, or bypass event), type of overflow structure (e.g., manhole, combined sewer overflow outfall), discharge volume untreated by the treatment works treating domestic sewage, types of human health and environmental impacts of the event, and whether the noncompliance was related to wet weather.

As of December 2025, all reports related to combined sewer overflows, sanitary sewer overflows, or bypass events must be submitted to the Regional Water Board and must be submitted electronically to the initial recipient defined in Standard Provisions – Reporting 5.10. The reports shall comply with 40 C.F.R. part 3, 40 C.F.R. section 122.22, and 40 C.F.R. part 127. The Regional Water Board may also require the Permittee to electronically submit reports not related to combined sewer overflows, sanitary sewer overflows, or bypass events under this section. (40 C.F.R. § 122.41(l)(6)(i).)

5.5.2. The following shall be included as information that must be reported within 24 hours:

5.5.2.1. Any unanticipated bypass that exceeds any effluent limitation in this Order. (40 C.F.R. § 122.41(l)(6)(ii)(A).)

5.5.2.2. Any upset that exceeds any effluent limitation in this Order. (40 C.F.R. § 122.41(l)(6)(ii)(B).)

5.5.3. The Regional Water Board may waive the above required written report on a case-by-case basis if an oral report has been received within 24 hours. (40 C.F.R. § 122.41(l)(6)(ii)(B).)

5.6. Planned Changes
The Permittee shall give notice to the Regional Water Board as soon as possible of any planned physical alterations or additions to the permitted facility. Notice is required under this provision only when (40 C.F.R. § 122.41(l)(1)):

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5.6.1. The alteration or addition to a permitted facility may meet one of the criteria for determining whether a facility is a new source in section 122.29(b) (40 C.F.R. § 122.41(l)(1)(i)); or

5.6.2. The alteration or addition could significantly change the nature or increase the quantity of pollutants discharged. This notification applies to pollutants that are not subject to effluent limitations in this Order. (40 C.F.R. § 122.41(l)(1)(ii).)

5.6.3. The alteration or addition could significantly change the nature or increase the quantity of pollutants discharged. This notification applies to pollutants that are subject neither to effluent limitations in this Order nor to notification requirements under section 122.42(a)(1) (see Additional Provisions— Notification Levels 7.1.1). (40 C.F.R. § 122.41(l)(1)(ii))

5.7. Anticipated Noncompliance
The Permittee shall give advance notice to the Regional Water Board of any planned changes in the permitted facility or activity that may result in noncompliance with this Order’s requirements. (40 C.F.R. § 122.41(l)(2).)

5.8. Other Noncompliance
The Permittee shall report all instances of noncompliance not reported under Standard Provisions – Reporting 5.3, 5.4, and 5.5 above at the time monitoring reports are submitted. The reports shall contain the information listed in Standard Provision – Reporting 5.5 above. For noncompliance events related to combined sewer overflows, sanitary sewer overflows, or bypass events, these reports shall contain the information described in Standard Provision – Reporting 5.5 and the applicable required data in appendix A to 40 C.F.R. part 127. The Regional Water Board may also require the Permittee to electronically submit reports not related to combined sewer overflows, sanitary sewer overflows, or bypass events under this section. (40 C.F.R. § 122.41(l)(7).)

5.9. Other Information
When the Permittee becomes aware that it failed to submit any relevant facts in a permit application, or submitted incorrect information in a permit application or in any report to the Regional Water Board, State Water Board, or U.S. EPA, the Permittee shall promptly submit such facts or information. (40 C.F.R. § 122.41(l)(8).)

5.10. Initial Recipient for Electronic Reporting Data
The owner, operator, or the duly authorized representative is required to electronically submit NPDES information specified in appendix A to 40 C.F.R. part 127 to the initial recipient defined in 40 C.F.R. section 127.2(b). U.S. EPA will identify and publish the list of initial recipients on its website and in the Federal CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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Register, by state and by NPDES data group [see 40 C.F.R. section 127.2(c)].

U.S. EPA will update and maintain this listing. (40 C.F.R. § 122.41(l)(9).)

6. STANDARD PROVISIONS – ENFORCEMENT

6.1. The Regional Water Board is authorized to enforce the terms of this permit under several provisions of the Water Code, including, but not limited to, sections 13268, 13350, 13385, 13386, and 13387.

7. ADDITIONAL PROVISIONS – NOTIFICATION LEVELS

7.1. Publicly-Owned Treatment Works (POTWs)
All POTWs shall provide adequate notice to the Regional Water Board of the following (40 C.F.R. § 122.42(b)):

7.1.1. Any new introduction of pollutants into the POTW from an indirect discharger that would be subject to sections 301 or 306 of the CWA if it were directly discharging those pollutants (40 C.F.R. § 122.42(b)(1)); and

7.1.2. Any substantial change in the volume or character of pollutants being introduced into that POTW by a source introducing pollutants into the POTW at the time of adoption of the Order. (40 C.F.R. § 122.42(b)(2).)

7.1.3. Adequate notice shall include information on the quality and quantity of effluent introduced into the POTW as well as any anticipated impact of the change on the quantity or quality of effluent to be discharged from the POTW. (40 C.F.R. § 122.42(b)(3)).

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MONITORING AND REPORTING PROGRAM

TABLE OF CONTENTS

1. General Monitoring Provisions .............................................................................E-3

2. Monitoring Locations ............................................................................................E-5

3. Influent Monitoring Requirements ........................................................................E-6

3.1. Monitoring Location INF-001 .............................................................................E-6

4. Effluent Monitoring Requirements ........................................................................E-7

4.1. Monitoring Location EFF-001 ............................................................................E-7

5. Whole Effluent Toxicity Testing Requirements...................................................E-10

5.1. Chronic Toxicity Testing ..................................................................................E-10

5.2. Toxicity Reduction Evaluation (TRE) Process .................................................E-15

6. Land Discharge Monitoring Requirements – Not Applicable ..............................E-17

7. Recycling Monitoring Requirements...................................................................E-17

7.1. Monitoring Location REC-001..........................................................................E-17

8. Receiving Water Monitoring Requirements........................................................E-18

8.1. Monitoring Location RSW-001.........................................................................E-18

8.2. Groundwater Monitoring – Not Required .........................................................E-19

9. Other Monitoring Requirements .........................................................................E-20

9.1. Outfall Inspection.............................................................................................E-20

9.2. Biological Survey.............................................................................................E-20

9.3. Filtration Process Monitoring (Monitoring Locations INT-001A and INT001B)...............................................................................................................E-20

9.4. Chlorine Disinfection Process Monitoring (Monitoring Location INT-002A) .....E-21

9.5. Ultraviolet Light Disinfection Process Monitoring (Monitoring Location INT002B)...............................................................................................................E-22

9.6. Sludge Monitoring (Monitoring Location BIO-001)...........................................E-23

9.7. Septage Station Monitoring (Monitoring Location SEP-001) ...........................E-23

10. Reporting Requirements ....................................................................................E-24

10.1. Special Studies, Technical Reports and Additional Monitoring Requirements ..................................................................................................E-24

10.2. General Monitoring and Reporting Requirements......................................E-25

10.3. Self-Monitoring Reports (SMRs) ................................................................E-25

10.4. Discharge Monitoring Reports (DMRs) ......................................................E-29

10.5. Other Reports ............................................................................................E-29

10.6. Spill Notification .........................................................................................E-35 CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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TABLE OF TABLES
Table E-1. Monitoring Station Locations.......................................................................E-5 Table E-2. Influent Monitoring ......................................................................................E-6 Table E-3. Effluent Monitoring......................................................................................E-7 Table E-4. Recycled Water Monitoring Requirements................................................E-17 Table E-5. Receiving Water Monitoring Requirements – Monitoring Location RSW-001 ...........................................................................................................E-18 Table E-6. Internal Effluent Monitoring – Monitoring Location INT-002A....................E-21 Table E-7. Septage Monitoring – Monitoring Location SEP-001 ................................E-23 Table E-8. Monitoring Periods and Reporting Schedule.............................................E-26 Table E-9. Reporting Requirements for Special Provisions Reports ..........................E-29 CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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ATTACHMENT E – MONITORING AND REPORTING PROGRAM (MRP)
Section 308 of the federal Clean Water Act (CWA) and sections 122.41(h), (j)-(l), 122.44(i), and 122.48 of title 40 of the Code of Federal Regulations (40 C.F.R.) require that all NPDES permits specify monitoring and reporting requirements. Water Code sections 13267 and 13383 also authorize the Regional Water Board to establish monitoring, inspection, entry, reporting, and recordkeeping requirements. This MRP establishes monitoring, reporting, and recordkeeping requirements that implement the federal and California laws and/or regulations.

1. GENERAL MONITORING PROVISIONS

1.1. Wastewater Monitoring Provision. Composite samples may be taken by a proportional sampling device approved by the Executive Officer or by grab samples composited in proportion to flow. In compositing grab samples, the sampling interval shall not exceed 1 hour.

1.2. Supplemental Monitoring Provision. If the Permittee monitors any pollutant more frequently than required by this Order, using test procedures approved by 40 C.F.R. part 136 or as specified in this Order, the results of such monitoring shall be included in the calculation and reporting of the data submitted in the monthly and annual discharge monitoring reports.

1.3. Laboratory Certification. Laboratories analyzing monitoring samples shall be certified by the State Water Resources Control Board (State Water Board) in accordance with the provisions of Water Code section 13176, and must include quality assurance/quality control data with their analytical reports.

The Permittee may analyze pollutants with short hold times (e.g., pH, chlorine residual, etc.) with field equipment or its on-site laboratory provided that the Permittee has written standard operating procedures (SOPs) that identify quality assurance/quality control procedures to be followed to ensure accurate results.

The Permittee must demonstrate sufficient capability to adequately perform these field tests (e.g., qualified and trained employees, properly calibrated and maintained field instruments). The program shall conform to U.S. EPA guidelines or other approved procedures.

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1.4. Instrumentation and Calibration Provision. All monitoring instruments and devices used by the Permittee to fulfill the prescribed monitoring program shall be properly maintained and calibrated as necessary to ensure their continued accuracy. All flow measurement devices shall be calibrated no less than the manufacturer’s recommended intervals or one year intervals, (whichever comes first) to ensure continued accuracy of the devices.

1.5. Minimum Levels (ML) and Reporting Levels (RL). U.S. EPA published regulations for the Sufficiently Sensitive Methods Rule (SSM Rule) which became effective September 18, 2015. Unless otherwise specified by this MRP, all monitoring shall be conducted according to test procedures established at 40 C.F.R. 136, Guidelines Establishing Test Procedures for Analysis of Pollutants. All analyses shall be conducted using the lowest practical quantitation limit achievable using U.S. EPA approved methods. For the purposes of the NPDES program, when more than one test procedure is approved under 40 C.F.R., part 136 for the analysis of a pollutant or pollutant parameter, the test procedure must be sufficiently sensitive as defined at 40 C.F.R. 122.21(e)(3) and 122.44(i)(1)(iv).

A U.S. EPA-approved analytical method is sufficiently sensitive where:

1.5.1. The ML is at or below both the level of the applicable water quality criterion/objective and the permit limitation for the measured pollutant or pollutant parameter; or

1.5.2. In permit applications, the ML is above the applicable water quality criterion/objective, but the amount of the pollutant or pollutant parameter in a facility's discharge is high enough that the method detects and quantifies the level of the pollutant or pollutant parameter in the discharge; or

1.5.3. The method has the lowest ML of the U.S. EPA-approved analytical methods where none of the U.S. EPA-approved analytical methods for a pollutant can achieve the MLs necessary to assess the need for effluent limitations or to monitor compliance with a permit limitation.

Where effluent limitations are set below the lowest achievable quantitation limits, pollutants not detected at the lowest practical quantitation limits will be considered in compliance with effluent limitations. Analysis for toxics listed in Table 3 of the Water Quality Control Plan for Ocean Waters of California, California Ocean Plan (2019) (Ocean Plan) shall also adhere to guidance and requirements contained in the Ocean Plan. However, there may be situations when analytical methods are published with MLs that are more sensitive than the MLs for analytical methods listed in the Ocean Plan. For instance, U.S. EPA Method 1631E for mercury is not currently listed in Ocean Plan Appendix II, but it is published with an ML of 0.5 ng/L that makes it a sufficiently sensitive analytical method. Similarly, U.S. EPA Method 245.7 for mercury is published with an ML of 5 ng/L.

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1.6. Discharge Monitoring Report Quality Assurance (DMR-QA) Study. The Permittee shall participate in the DMR-QA program and ensure that the results of the DMR-QA Study or the most recent Water Pollution Performance Evaluation Study from each laboratory providing testing services for the permit are submitted annually to the State Water Board at [email protected]. For more information on the DMR-QA Program, contact the State DMR-QA Coordinator at the aforementioned email address.

2. MONITORING LOCATIONS
The Permittee shall establish the following monitoring locations to demonstrate compliance with the effluent limitations, discharge specifications, and other requirements in this Order:

Table E-1. Monitoring Station Locations
Discharge
Point Name
Monitoring
Location Name Monitoring Location Description
-- INF-001
Influent wastewater prior to treatment and following
all significant input of waste to the treatment system
and consisting of wastewater from both the collection
system and any future septage receiving station.
-- INT-001A
Internal monitoring location for monitoring the surface loading rate through the membrane bioreactor (MBR)
system.
-- INT-001B
Internal monitoring location for monitoring the turbidity of treated effluent immediately following the MBR
system.
-- INT-002A
Internal Monitoring location for purpose of
demonstrating the presence of a chlorine residual at
the end of the chlorine contact tank.
-- INT-002B
Internal monitoring location for monitoring ultraviolet light (UV) radiation dose and UV transmittance of the
UV disinfection system.
001 EFF-001
A location where representative samples of the
treated wastewater to be discharged to the Pacific
Ocean at Discharge Point 001 can be collected at a
point after treatment, including
chlorination/dechlorination, and before contact with
the receiving water.

Latitude: 41° 44’ 38” Longitude: -124° 12’ 10”
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Discharge
Point Name
Monitoring
Location Name Monitoring Location Description
002 REC-001
Location where the flow rate of recycled water can be
monitored and representative samples of treated
wastewater to be distributed to the recycled water
system can be collected.
-- RSW-001
Location in the receiving water in the vicinity of the
outfall, within the waste field where initial dilution is completed.
-- SEP-001
Septage receiving station after complete mixing of
septage wastes and prior to the headworks. This
station may be established upon receipt and Regional
Water Board Executive Officer approval of a Septage
Management Plan.
-- BIO-001 A representative sample of the sludge or biosolids generated when removed for disposal.

The North latitude and West longitude information in Table E-1 are approximate for administrative purposes. Monitoring Locations INT-001A, INT-001B, and REC-001 are applicable if the Permittee produces and distributes recycled water.

3. INFLUENT MONITORING REQUIREMENTS

3.1. Monitoring Location INF-001

3.1.1. The Permittee shall monitor influent to the facility at Monitoring Location INF-001 as follows:

Table E-2. Influent Monitoring
Parameter Units Sample Type
Minimum
Sampling
Frequency
Required
Analytical Test
Method1
Influent Flow2 mgd Meter Continuous --
Biochemical
Oxygen
Demand 5-day
@ 20°C
(BOD5)
3 mg/l 24-hr Composite Weekly Standard
Methods
Total
Suspended
Solids (TSS)
mg/l 24-hr Composite Weekly Standard
Methods
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Parameter Units Sample Type
Minimum
Sampling
Frequency
Required
Analytical Test
Method1
Ocean Plan
Table 3
4 μg/L Grab/Composite5 Once per permit
term6
Standard
Methods
Table Notes:

1. In accordance with the current edition of Standard Methods for Examination of Water and Wastewater (American Public Health Administration) or current test procedures specified in 40 C.F.R. part 136.

2. Each month, the Permittee shall report the average daily and average monthly flows.

3. For purposes of determining percent removal of BOD5, the Permittee may sum the BOD5 mass computed from samples collected at INF-001 and the BOD5 mass removed by the Rumiano Cheese Company pretreatment process during the same interval. The Permittee must provide and certify pretreatment data considered in percent removal determinations.

4. Excluding acute and chronic toxicity and total chlorine residual.

5. Grab samples shall be used for volatile chemicals listed in Table II-1 of the Ocean Plan (2012). 24-hour composite samples shall be used for all other Ocean Plan Table 1 parameters.

6. Within the first year of the permit term.

4. EFFLUENT MONITORING REQUIREMENTS

4.1. Monitoring Location EFF-001

4.1.1. The Permittee shall monitor treated effluent at Monitoring Location EFF-001 during periods of discharge to the Pacific Ocean at Discharge Point 001 as follows. If more than one analytical test method is listed for a given parameter, the Permittee must select from the listed methods and corresponding Minimum Level:

Table E-3. Effluent Monitoring
Parameter Units Sample Type
Minimum
Sampling
Frequency
Required Analytical
Test Method1
Effluent
Flow2
mgd Meter Continuous --
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Parameter Units Sample Type
Minimum
Sampling
Frequency
Required Analytical
Test Method1
Biochemical
Oxygen
Demand 5-
day @ 20°C
(BOD5)
mg/L 24-hour
composite
Weekly3 Standard Methods
Total
Suspended
Solids (TSS)
mg/L 24-hour
composite
Weekly3 Standard Methods
Settleable
Solids
ml/L Grab Daily4 Standard Methods
Oil and
Grease
mg/L Grab Monthly5 Standard Methods
Turbidity NTU Grab Weekly3 Standard Methods
pH s.u. Grab Daily4 Standard Methods
Total
Coliform
Bacteria
MPN/100
ml
Grab Weekly Standard Methods
Fecal
Coliform
Bacteria
MPN/100
mL
Grab Weekly3 Standard Methods
Enterococcus
Bacteria
MPN/100
ml
Grab Weekly Standard Methods
Ammonia
Nitrogen,
Total (as N)
mg/L 24-hour
composite
Twice Weekly3 Standard Methods
Total
Residual
Chlorine6
mg/L Meter Continuous Standard Methods
Copper, Total
Recoverable
μg/L 24-hour
composite
Monthly5 Standard Methods
Silver, Total
Recoverable
μg/L 24-hour
composite
Quarterly5 Standard Methods
Endosulfans
7 μg/L Grab Quarterly5 Standard Methods
Endrin μg/L Grab Monthly5 Standard Methods
DDT8 μg/L Grab Quarterly5 Standard Methods
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Parameter Units Sample Type
Minimum
Sampling
Frequency
Required Analytical
Test Method1
Heptachlor μg/L Grab Quarterly5 Standard Methods
Dieldrin μg/L Grab Quarterly5 Standard Methods
Ocean Plan
Table 3
Pollutants9
μg/L Grab/Composite10 Annually5 Standard Methods
Chronic
Toxicity11
Pass or
Fail, %
Effect
Grab Annually See Section 5 below
Table Notes:

2. Each month, the Permittee shall report the daily average and monthly average flows.

3. Accelerated Monitoring (weekly monitoring frequency). If two consecutive weekly test results exceed an effluent limitation, the Permittee shall take two samples each of the two weeks following receipt of the second sample result. During the intervening period, the Permittee shall take steps to identify the cause of the exceedance and take steps to return to compliance.

4. Accelerated Monitoring (daily monitoring frequency). If a test result exceeds an effluent limitation, the Permittee shall increase the monitoring frequency to a minimum of twice a day for a week to evaluate whether the exceedance is persisting. If two or more samples in a week exceed an effluent limitation, the Permittee shall take steps to identify the cause of the exceedance and take steps needed to return to compliance.

5. Accelerated Monitoring (monthly, quarterly, and annual monitoring frequency). If a test result exceeds an effluent limitation the Permittee shall take two more samples, one within 7 days and one within 14 days following receipt of the initial sample result. During the intervening period, the Permittee shall take steps to identify the cause of the exceedance and take steps needed to return to compliance.

6. The Permittee shall report from discrete readings of the continuous monitoring every hour on the hour and report the average of the hourly readings on a daily basis in accordance with Compliance Determination section 7.12 of this Order. The Permittee shall calibrate chlorine residual analyzers against grab samples as frequently as necessary to maintain accurate and reliable operations.

7. Endosulfans shall mean the sum of endosulfan-alpha and –beta and endosulfan sulfate.

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Parameter Units Sample Type
Minimum
Sampling
Frequency
Required Analytical
Test Method1

8. DDT shall mean the sum of 4,4’-DDT, 2,4’-DDT, 4,4’-DDE, 2,4’-DDE, 4,4’-DDD, and 2,4’-DDD.

9. Excluding acute toxicity.

10.Grab samples shall be used for volatile chemicals listed in Table II-1 of the Ocean Plan (2019). 24-hour composite samples shall be used for all other Ocean Plan Table 3 parameters.

11.Whole effluent chronic toxicity shall be monitored in accordance with the requirements of section 5 of this Monitoring and Reporting Program.

5. WHOLE EFFLUENT TOXICITY TESTING REQUIREMENTS

5.1. Chronic Toxicity Testing
The Permittee shall conduct chronic toxicity testing in accordance with the following chronic toxicity testing requirements:

5.1.1. Test Frequency. The Permittee shall conduct chronic WET testing in accordance with the schedule established in this MRP, while discharging at Discharge Point 001, as summarized in Table E-3, above.

5.1.2. Discharge In-stream Waste Concentration (IWC) for Chronic Toxicity. The chronic toxicity IWC for this discharge is 3.451 percent effluent.

5.1.3. Sample Volume and Holding Time. The total sample volume shall be determined by the specific toxicity test method used. Sufficient sample volume shall be collected to perform the required toxicity test. All toxicity tests shall be conducted as soon as possible following sample collection.

For toxicity tests requiring renewals (Atherinops affinis), a minimum of three samples shall be collected. The lapsed time (holding time) from sample collection to first use of each sample must not exceed 36 hours.

5.1.4. Chronic Marine Test Species and Test Methods. If effluent samples are collected from outfalls discharging to receiving waters with salinity >1 ppt, the Permittee shall conduct the following chronic toxicity tests on effluent samples at the IWC for the discharge in accordance with species and test methods in Shortterm Methods for Estimating the Chronic Toxicity of Effluents and Receiving 1 The IWC is calculated using the approved dilution ratio of 29 to 1 (seawater to wastewater) as follows: (1 ÷ 29) x 100.

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Waters to West Coast Marine and Estuarine Organisms (EPA/600/R-95/136, 1995). Artificial sea salts or hypersaline brine prepared from natural seawater shall be used to increase sample salinity. In no case shall these species be substituted with another test species unless written authorization from the Executive Officer is received.

5.1.4.1. A static renewal toxicity test with the topsmelt, Atherinops affinis (Larval Survival and Growth Test Method 1006.0).

5.1.4.2. A static non-renewal toxicity test with the purple sea urchin, Strongylocentrotus purpuratus, and the sand dollar, Dendraster excentricus (Fertilization Test Method 1008.0), or a static non-renewal toxicity test with the mussel, Mytilus sp. (Embyro-Larval Shell Development Test Method).

5.1.4.3. A static non-renewal toxicity test with the giant kelp, Macrocystis pyrifera (Germination and Growth Test Method 1009.0).

5.1.5. Species Sensitivity Screening. Species sensitivity screening shall be conducted during this permit’s first required sample collection. The Permittee shall collect a single effluent sample and concurrently conduct three chronic toxicity tests using the fish, an invertebrate, and the alga species identified in section 5.1.4, above. This sample shall also be analyzed for the parameters required for the discharge. The species that exhibits the highest “Percent (%) Effect” at the discharge IWC during species sensitivity screening shall be used for routine monitoring during the permit term2
.

5.1.6. Quality Assurance and Additional Requirements. Quality assurance measures, instructions, and other recommendations and requirements are found in the test methods manual previously referenced. Additional requirements are specified below.

5.1.6.1. The discharge is subject to determination of “Pass” or “Fail” and “Percent (%) Effect” for chronic toxicity tests using the TST approach described in National Pollutant Discharge Elimination System Test of Significant Toxicity Implementation Document (EPA 833-R10-003, 2010), Appendix A, Figure A2 If the percent effect is less than or equal to zero percent effect for each species, or all percent effect are the same value, in the species sensitivity screening test, the Permittee shall either use the species that was most sensitive during the previous permit term for routine monitoring or repeat the species sensitivity screening for all species to confirm the results of the first screening before selecting the most sensitive species to use for routine monitoring. If two consecutive species sensitivity screening tests demonstrate that the percent effect for all species exhibit less than or equal to zero percent, the Permittee may select the species to be used for routine monitoring during the permit term.

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1, and Table A-1. The null hypothesis (Ho) for the TST approach is: Mean discharge IWC response ≤ 0.75 × Mean control response. A test result that rejects this null hypothesis is reported as “Pass”. A test result that does not reject this null hypothesis is reported as “Fail”. The relative “Percent (%) Effect” at the discharge IWC is defined and reported as: ((Mean control response - Mean discharge IWC response) ÷ Mean control response)) × 100.

5.1.6.2. If the effluent toxicity test does not meet the minimum effluent or reference toxicant test acceptability criteria (TAC) specified in the referenced test method, then the Permittee shall re-sample and re-test within 14 days.

5.1.6.3. Dilution water and control water, including brine controls, shall be laboratory water prepared and used as specified in the test methods manual. If dilution water and control water is different from test organism culture water, then a second control using culture water shall also be used.

5.1.6.4. Monthly reference toxicant testing is sufficient. All reference toxicant test results should be reviewed and reported.

5.1.6.5. The Permittee shall perform toxicity tests on final effluent samples collected at Monitoring Location EFF-001 (after chlorination and dechlorination). Ammonia shall not be removed from the effluent sample prior to toxicity testing, unless explicitly authorized under this section of the MRP and the rationale is explained in the Fact Sheet (Attachment F). If any chlorine is detected in the sample upon arrival at the analytical laboratory, the effluent sample may be further dechlorinated with anhydrous sodium thiosulfate to non-toxic levels in accordance with section 8.8.7 of the test method identified in section 5.1.4, above. The removal of chlorine by the analytical laboratory shall be clearly documented in the chronic toxicity report submitted to the Regional Water Board.

5.1.6.6. Ammonia Removal. Except with prior approval from the Executive Officer of the Regional Water Board, ammonia shall not be removed from bioassay samples. The Permittee must demonstrate the effluent toxicity is caused by ammonia because of increasing test pH when conducting the toxicity test. It is important to distinguish the potential toxic effects of ammonia from other pH sensitive chemicals, such as certain heavy metals, sulfide, and cyanide. The following may be steps to demonstrate that the toxicity is caused by ammonia and not other toxicants before the Executive Officer would allow for control of pH in the test.

5.1.6.6.1. There is consistent toxicity in the effluent and the maximum pH in the toxicity test is in the range to cause toxicity due to increased pH.

5.1.6.6.2. Chronic ammonia concentrations in the effluent are greater than 4 mg/L total ammonia.

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5.1.6.6.3. Conduct graduated pH tests as specified in the toxicity identification evaluation methods. For example, mortality should be higher at pH 8 and lower at pH 6.

5.1.6.6.4. Treat the effluent with a zeolite column to remove ammonia. Mortality in the zeolite treated effluent should be lower than the non-zeolite treated effluent.

Then add ammonia back to the zeolite-treated samples to confirm toxicity due to ammonia.

When it has been demonstrated that toxicity is due to ammonia because of increasing test pH, pH may be controlled using appropriate procedures which do not significantly alter the nature of the effluent.

5.1.7. Notification. The Permittee shall notify the Regional Water Board verbally within 72 hours and in writing within 14 days after the receipt of a result of “Fail” during routine or accelerated monitoring.

5.1.8. Accelerated Monitoring Requirements. The trigger for accelerated monitoring for chronic toxicity is exceeded when a chronic toxicity test, analyzed using the TST approach, results in “Fail” and the “Percent Effect” is ≥0.50. Within 24 hours of the time the Permittee becomes aware of a result of “Fail”, the Permittee shall implement an accelerated monitoring schedule consisting of four toxicity tests— consisting of 5-effluent concentrations (including the discharge IWC) and a control—conducted at approximately 2-week intervals, over an 8-week period. If each of the accelerated toxicity tests results is “Pass,” the Permittee shall return to routine monitoring for the next monitoring period. If one of the accelerated toxicity tests results is “Fail”, the Permittee shall immediately implement the TRE Process conditions set forth in section 5.2, below.

5.1.9. Reporting

5.1.9.1. Routine Reporting. Chronic toxicity monitoring results for effluent at Monitoring Location EFF-001 shall be submitted with the monthly selfmonitoring report (SMR) for the month in which chronic toxicity monitoring was performed. Routine reporting shall include the following in order to demonstrate compliance with permit requirements:

5.1.9.1.1. WET reports shall include the contracting laboratory’s complete report provided to the Permittee and shall be consistent with the appropriate “Report Preparation and Test Review” sections of the methods manual and this MRP. The WET test reports shall contain a narrative report that includes details about WET test procedures and results, including the following:

5.1.9.1.1.1. Receipt and handling of the effluent sample that includes a tabular summary of initial water quality characteristics (e.g., pH, dissolved oxygen, temperature, conductivity, hardness, salinity, chlorine, ammonia); CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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5.1.9.1.1.2. The source and make-up of the lab control/diluent water used for the test;

5.1.9.1.1.3. Any manipulations done to lab control/diluent and effluent such as filtration, nutrient addition, etc.;

5.1.9.1.1.4. Identification of any reference toxicant testing performed;

5.1.9.1.1.5. Tabular summary of test results for control water and each effluent dilution and statistics summary to include calculation of the NOEC, TUc, and IC25;

5.1.9.1.1.6. The toxicity test results for the TST approach, reported as “Pass” or “Fail” and “Percent (%) Effect” at the chronic toxicity IWC for the discharge;

5.1.9.1.1.7. Identification of any anomalies or nuances in the test procedures or results;

5.1.9.1.1.8. Summary and conclusions section.

5.1.9.1.1.9. WET test results shall include, at a minimum, for each test:

5.1.9.1.1.9.1. Sample date(s);

5.1.9.1.1.9.2. Test initiation date;

5.1.9.1.1.9.3. Test species;

5.1.9.1.1.9.4. Determination of “Pass” or “Fail” and “Percent Effect” following the Test of Significant Toxicity hypothesis testing approach in National Pollutant Discharge Elimination System Test of Significant Toxicity Implementation Document (EPA 833-R-10-003, 2010). The “Percent Effect” shall be calculated as follows:
“Percent Effect” (or Effect, in %) = ((Control mean response – IWC mean response) ÷ Control mean response)) x 100

5.1.9.1.1.9.5. End point values for each dilution (e.g., number of young, growth rate, percent survival);

5.1.9.1.1.9.6. NOEC value(s) in percent effluent;

5.1.9.1.1.9.7. IC15, IC25, IC40, and IC50 values (or EC15, EC25…etc.) in percent effluent;

5.1.9.1.1.9.8. TUc values (100/NOEC);

5.1.9.1.1.9.9. Mean percent mortality (±s.d.) after 96 hours in 100 percent effluent (if applicable);
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5.1.9.1.1.9.10. NOEC and LOEC values for reference toxicant test(s);

5.1.9.1.1.9.11. IC50 or EC50 value(s) for reference toxicant test(s);

5.1.9.1.1.9.12. Available water quality measurements for each test (e.g., pH, DO, temperature, conductivity, hardness, salinity, ammonia);

5.1.9.1.1.9.13. Statistical methods used to calculate endpoints;

5.1.9.1.1.9.14. The statistical program (e.g., TST calculator, CETIS, etc.) output results, which includes the calculation of percent minimum significant difference (PMSD); and

5.1.9.1.1.9.15. Results of applicable reference toxicant data with the statistical output page identifying the species, NOEC, LOEC, type of toxicant, dilution water used, concentrations used, PMSD and dates tested; the reference toxicant control charts for each endpoint, to include summaries of reference toxicant tests performed by the contracting laboratory; and any information on deviations from standard test procedures or problems encountered in completing the test and how the problems were resolved.

5.1.9.2. TRE/TIE Results. The Executive Officer shall be notified no later than 30 days from completion of each aspect of TRE/TIE analyses. TRE/TIE results shall be submitted to the Regional Water Board within 60 days of completion.

5.2. Toxicity Reduction Evaluation (TRE) Process

5.2.1. TRE Work Plan. The Permittee submitted a revised TRE Work Plan to the Regional Water Board on October 1, 2014. The Permittee’s TRE Work Plan shall be reviewed by February 1, 2025 for consistency with permit requirements and the Permittee’s procedures updated as necessary in order to remain current and applicable to the discharge and requirements of this Order.

The Permittee shall notify the Regional Water Board of this review and submit any revisions of the TRE Work Plan within 90 days of the notification, to be ready to respond to toxicity events. The TRE Work Plan shall describe the steps the Permittee intends to follow if toxicity is detected, and should include at least the following items:

5.2.1.1. A description of the investigation and evaluation techniques that would be used to identify potential causes and sources of toxicity, effluent variability, and treatment system efficiency.

5.2.1.2. A description of the facility’s methods of maximizing in-house treatment efficiency, good housekeeping practices, and a list of all chemicals used in the operation of this Facility.

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5.2.1.3. If a toxicity identification evaluation (TIE) is necessary, an indication of the person who would conduct the TIEs (i.e., an in-house expert or an outside contractor).

5.2.2. Preparation and Implementation of a Detailed TRE Work Plan. If one of the accelerated toxicity tests described in section V.A.8, above, results in “Fail”, the Permittee shall immediately initiate a TRE using, according to type of treatment facility, EPA manual Generalized Methodology for Conducting Industrial Toxicity Reduction Evaluations (EPA/600/2-88/070, 1989) and within 30 days of receipt of the accelerated monitoring result submit to the Regional Water Board Executive Officer a Detailed TRE Work Plan, which shall follow the generic TRE Work Plan revised as appropriate for the toxicity event described in section 5.1.8 of this MRP. The Detailed TRE Work Plan shall include the following information, and comply with additional conditions set by the Regional Water Board Executive Officer:

5.2.2.1. Further actions by the Permittee to investigate, identify, and correct causes of toxicity.

5.2.2.2. Actions the Permittee will take to mitigate effects of the discharge and prevent the recurrence of toxicity.

5.2.2.3. A schedule for these actions, progress reports, and the final report.

5.2.3. TIE Implementation. The Permittee may initiate a TIE as part of a TRE to identify the causes of toxicity using the same species and test methods and, as guidance, EPA manuals: Methods for Aquatic Toxicity Identification Evaluations:

Phase I Toxicity Characterization Procedures (EPA/600/6-91/003, 1991); Methods for Aquatic Toxicity Identification Evaluations, Phase II Toxicity Identification Procedures for Samples Exhibiting Acute and Chronic Toxicity (EPA/600/R-92/080, 1993); Methods for Aquatic Toxicity Identification Evaluations, Phase III Toxicity Confirmation Procedures for Samples Exhibiting Acute and Chronic Toxicity (EPA/600/R-92/081, 1993); and Marine Toxicity Identification Evaluation (TIE): Phase I Guidance Document (EPA/600/R-96- 054, 1996). The TIE should be conducted on the species demonstrating the most sensitive toxicity response.

5.2.4. Many recommended TRE elements parallel required or recommended efforts for source control, pollution prevention, and storm water control programs. TRE efforts should be coordinated with such efforts. As toxic substances are identified or characterized, the Permittee shall continue the TRE by determining the sources and evaluating alternative strategies for reducing or eliminating the substances from the discharge. All reasonable steps shall be taken to reduce toxicity to levels consistent with toxicity evaluation parameters.

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5.2.5. The Permittee shall conduct routine effluent monitoring for the duration of the TRE process. Additional accelerated monitoring and TRE work plans are not required once a TRE has begun.

5.2.6. The Regional Water Board recognizes that toxicity may be episodic and identification of the causes and reduction of sources of toxicity may not be successful in all cases. The TRE may be ended at any stage if monitoring finds there is no longer toxicity.

6. LAND DISCHARGE MONITORING REQUIREMENTS – NOT APPLICABLE This Order does not authorize discharges to land.

7. RECYCLING MONITORING REQUIREMENTS
The following requirements apply after the Permittee implements a recycled water system.

7.1. Monitoring Location REC-001

7.1.1. The Permittee shall monitor effluent to the recycled water system at Monitoring Location REC-001 as follows:

Table E-4. Recycled Water Monitoring Requirements
Parameter Units Sample Type
Minimum
Sampling
Frequency
Required
Analytical Test
Method1
Effluent Flow2 mgd Meter Continuous
Biochemical
Oxygen
Demand 5-day
@ 20°C (BOD5)
mg/L 24-hour
composite
Weekly Standard
Methods
Total
Suspended
Solids (TSS)
mg/L 24-hour
composite
Weekly Standard
Methods
pH s.u. Grab Weekly Standard
Methods
Total Coliform
Bacteria
MPN/100 ml Grab Daily Standard
Methods
Nitrate Nitrogen,
Total (as N)3
mg/L Grab Monthly Standard
Methods
Nitrite Nitrogen
(as N)3
mg/L Grab Monthly Standard
Methods
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Parameter Units Sample Type
Minimum
Sampling
Frequency
Required
Analytical Test
Method1
Ammonia
Nitrogen (as N)3
mg/L 24-hour
composite
Monthly Standard
Methods
Organic
Nitrogen (as N)3
mg/L Grab Monthly Standard
Methods
Total Dissolved
Solids (TDS)
mg/L Grab Monthly4 Standard
Methods
Table Notes:

2. Each month, the Permittee shall report the daily average and monthly average flows.

3. Monitoring for nitrate, nitrite, ammonia, and organic nitrogen is for the purpose of determining total nitrogen concentration for agronomic rate calculations.

4. The monitoring frequency for TDS may be reduced to annually if the first 12 months of monitoring data collected after the effective date of this Order demonstrate that concentrations of TDS are consistently lower than water quality objectives for protection of groundwater.

7.1.2. The Permittee shall comply with Water Recycling Specifications and Requirements contained in section 4.3 of this Order:

8. RECEIVING WATER MONITORING REQUIREMENTS

8.1. Monitoring Location RSW-001

8.1.1. The Permittee shall monitor the Pacific Ocean at Monitoring Location RSW-001 as follows:

Table E-5. Receiving Water Monitoring Requirements – Monitoring Location RSW001 Parameter Units Sample Type
Minimum
Sampling
Frequency
Required
Analytical Test
Method1
Fecal Coliform
Bacteria2
MPN/100 ml Grab Weekly Standard
Methods
Total Coliform
Bacteria2
MPN/100 ml Grab Weekly Standard
Methods
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Parameter Units Sample Type
Minimum
Sampling
Frequency
Required
Analytical Test
Method1
Enterococcus
Bacteria3
MPN/100 ml Grab Weekly Standard
Methods
Table Notes:

2. Test methods used for coliforms (total and fecal) shall be those presented in Table 1A of 40 CFR Part 136, unless alternate methods have been approved in advance by U.S. EPA pursuant to 40 CFR Part 136.

3. Test methods used for enterococcus shall be those presented in EPA publication EPA 600/4-85/076, Test Methods for Escherichia coli and Enterococci in Water By Membrane Filter Procedure, or any improved method determined by the Regional Water Board to be appropriate. The Regional Water Board finds that the methods presented in Table 1A of 40 C.F.R. Part 136 are appropriate methods to use for the analysis of enterococcus bacteria.

8.1.2. The geometric mean for fecal coliform density shall be calculated using the five most recent sample results for comparison with the 30-day geometric mean receiving water limitation in section 5.1.1.1.1.1 of this Order. The 6-week rolling geometric mean for enterococci shall be calculated weekly for comparison with the 30-day geometric mean receiving water limitation in section 5.1.1.1.1.2 of this Order.

8.1.3. If a single sample exceeds any of the single sample maximum receiving water limitations in sections 5.1.1.1.1 and 5.1.1.1.2 of this Order, the Permittee shall conduct repeat sampling at that location to determine the extent and persistence of the exceedance. Repeat sampling shall be conducted within 24 hours of receiving analytical results and continued every 24 hours until the sample result is less than the single sample maximum receiving water limitation or until a sanitary survey is conducted to determine the source of the high bacterial densities.

When repeat sampling is required because of an exceedance of any one single sample density, values from all samples collected during that 30-day period will be used to calculate the geometric mean.

8.2. Groundwater Monitoring – Not Required
This Order does not require groundwater monitoring at this time.

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9. OTHER MONITORING REQUIREMENTS

9.1. Outfall Inspection
The Permittee shall conduct a comprehensive evaluation/inspection of the outfall once during the term of the permit to verify the operational status and integrity of the outfall. By June 1, 2024, the Permittee shall submit to the Regional Water Board Executive Officer for approval, an Outfall Inspection/Evaluation Work Plan identifying the evaluation and inspection plan, methodology, and timeline for conducting the outfall inspection. A report documenting the results of the outfall inspection and evaluation shall be submitted no later than April 1, 2026. The report shall include a description of the outfall condition, including any observed cracks, breaks, leaks, or other malfunctions, and identify any needed maintenance and repairs.

9.2. Biological Survey
The Permittee shall conduct a comparative evaluation of indigenous biota in the vicinity of the outfall and a reference station outside the influence of the discharge using a qualified aquatic biologist at least once every 5 years. The biologist shall prepare a report that includes a photographic survey of the intertidal flora and fauna and observations of objectionable aquatic growths, floating particulates or grease and oil, aesthetically undesirable discoloration of the ocean surface, color of fish or shellfish, and any evidence of degradation of indigenous biota attributable to the rate of deposition of inert solids, settleable material, nutrient materials, increased concentrations of organic materials, or increased concentrations of Ocean Plan Table 3 substances. The Permittee shall submit to the Regional Water Board Executive Officer for approval a Biological Survey Work Plan no later than December 1, 2024, in order to complete the survey and prepare a final report by the due date for receipt of an application for permit renewal. The final report shall be submitted no later than June 1, 2027.

9.3. Filtration Process Monitoring (Monitoring Locations INT-001A and INT-001B) If the Permittee produces and distributes recycled water, filtration process monitoring shall demonstrate compliance with section 4.3.3 (Filtration Process Requirements) of the Order and applies to discharges to the recycled water system. The Permittee is required to implement the following filtration process monitoring:

9.3.1. Effluent Filter Monitoring (Monitoring Location INT-001A)

9.3.1.1. Monitoring. The Permittee shall calculate on a daily basis the surface loading rate in gallons per minute per square meter and report the maximum surface loading rate and any exceedances of the surface loading rate limitations specified in section 4.3.3.1 of the Order. The rate of flow through the tertiary filters shall be measured at Monitoring Location INT-001A.

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9.3.1.2. Compliance. Compliance with the maximum daily filter surface loading rate, as specified in section 60301.320 of the CCR Water Recycling Criteria (title 22), shall be calculated based on the flow rate through each filter unit.

9.3.1.3. Reporting. The maximum daily filter surface loading rate shall be reported on the monthly SMR.

9.3.2. Effluent Filter Monitoring (Monitoring Location INT-001B)

9.3.2.1. Monitoring. The turbidity of the filtered effluent shall be continuously measured and recorded at Monitoring Location INT-001B. Should the turbidity meter and recorder fail, grab sampling at a minimum frequency of 1.2 hours may be substituted for a period of up to 24 hours. The recorded data shall be maintained by the Permittee for at least 3 years. The daily maximum and 95th percentile turbidity results shall be reported on the monthly SMRs.

9.3.2.2. Compliance. Compliance with the effluent turbidity limitation specified in title 22, as referenced in section 4.3.3.2 of the Order, shall be determined using the levels of recorded turbidity taken at intervals of no more than 1.2 hours over a 24-hour period.

9.3.2.3. Reporting. If the filtered effluent turbidity exceeds 0.2 NTU for more than 5 percent of the time in a 24-hour period or 0.5 NTU at any time, the incident shall be reported in the monthly SMR and to the Regional Water Board and DDW by telephone within 24 hours in accordance with Provision 4.3.3.3 of the Order, only if the effluent was sent to the recycled water system. A written report describing the incident and the actions undertaken in response shall be included in the monthly SMR. Mitigation of the event shall consist of diverting all inadequately treated wastewater to temporary storage or an upstream process or automatically activated chemical addition to comply with title 22 requirements (sections 60304 and 60307).

9.4. Chlorine Disinfection Process Monitoring (Monitoring Location INT-002A)

9.4.1. The Permittee shall monitor the discharge from the chlorine contact chamber prior to dechlorinating at Monitoring Location INT-001A as follows:

Table E-6. Internal Effluent Monitoring – Monitoring Location INT-002A Parameter Units Sample Type
Minimum
Sampling
Frequency
Required
Analytical Test
Method1
Chlorine, Total
Residual2
mg/L Meter Continuous Standard
Methods
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Parameter Units Sample Type
Minimum
Sampling
Frequency
Required
Analytical Test
Method1
Table Notes:

2. The Permittee shall monitor continuously to demonstrate that the appropriate chlorine residual concentration is maintained in the effluent at INT-002A at all times. At a minimum, the Permittee shall record readings of the continuous monitoring every hour on the hour and report the maximum recorded daily chlorine residual. The Permittee shall calibrate chlorine residual analyzers against grab samples as frequently as necessary to maintain accurate and reliable operation.

9.5. Ultraviolet Light Disinfection Process Monitoring (Monitoring Location INT002B) If the Permittee produces and distributes recycled water, disinfection process monitoring shall demonstrate compliance with section 4.3.4 (Disinfection Process Requirements) of the Order and applies to discharges to the recycled water system. The Permittee is required to implement the following disinfection process monitoring:

9.5.1. Monitoring Location INT-002B

9.5.1.1. Monitoring. The UV transmittance of the effluent from the UV disinfection system shall be monitored continuously and recorded at Monitoring Location INT-002B. The operational UV dose shall be calculated from UV transmittance and flow.

9.5.1.2. Compliance. The UV transmittance shall not fall below 65 percent of maximum at any time, unless otherwise approved by DDW. The operational UV dose shall not fall below 80 millijoules per square centimeter (mJ/cm2) at any time, unless otherwise approved by DDW. Flow through the UV disinfection system shall not exceed 0.6 mgd, unless otherwise approved by DDW.

9.5.1.3. Reporting. The Permittee shall report daily average and lowest daily transmittance and operational UV dose on its monthly SMRs. The Permittee shall report daily average and maximum flow through the UV disinfection system. If the UV transmittance falls below 65 percent or UV dose falls below 80 mJ/cm2, the event shall be reported to the Regional Water Board by telephone within 24 hours. Any inadequately treated and disinfected wastewater shall be diverted to a storage basin or an upstream process for adequate treatment.

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9.6. Sludge Monitoring (Monitoring Location BIO-001)

9.6.1. Sludge sampling shall be conducted according to the requirements specified by the location and type of disposal activities undertaken.

9.6.2. Sampling records shall be retained for a minimum of 5 years. A log shall be maintained for sludge quantities generated and for handling and disposal activities. The frequency of entries is discretionary; however, the log must be complete enough to serve as a basis for developing the Sludge Handling and Disposal report that is required as part of the Annual Report.

9.7. Septage Station Monitoring (Monitoring Location SEP-001) Upon Regional Water Board approval of a septage management program, the following requirements apply when the Facility is receiving septage.

9.7.1. Monitoring Location SEP-001

9.7.1.1. For each septage load delivered to the Facility, the Permittee shall require the hauler to collect and report a pH value representative of the load.

9.7.1.2. The Permittee shall estimate, prior to the beginning of a quarterly and semiannual monitoring period, the number of anticipated septage deliveries for the given monitoring frequency, and generate a random load number from this total. When the delivery corresponding to the pre-chosen random number is received, the Permittee will collect a representative septage sample and have the samples analyzed in accordance with Table E-7 and with standard sample collection and handling procedures. Each sample shall be analyzed in accordance with the following table:

Table E-7. Septage Monitoring – Monitoring Location SEP-001 Parameter Units Sample Type
Minimum
Sampling
Frequency
Required
Analytical Test
Method1
pH s.u. Meter Continuous Standard
Methods
Biochemical
Oxygen
Demand
mg/L Grab Quarterly Standard
Methods
Chemical
Oxygen
Demand
mg/L Grab Quarterly Standard
Methods
Oil and Grease mg/L Grab Quarterly Standard
Methods
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Parameter Units Sample Type
Minimum
Sampling
Frequency
Required
Analytical Test
Method1
Metals and
Trace Elements
μg/L Grab Quarterly Standard
Methods
Purgeable
Organic
Compounds2
μg/L Grab Semiannually Standard
Methods
Semivolatile
Organic
Compounds3
μg/L Grab Semiannually Standard
Methods

2. Purgeable organic compounds shall include the parameters listed in U.S. EPA Method 624.

3. Semivolatile organic compounds shall include the parameters listed in U.S. EPA Method 625.

9.7.2. Septage Hauler Tracking

9.7.2.1. For any month when septage waste is received by the Facility, the source(s) of the waste shall be documented. A summary table of all septage discharged to the Facility shall be submitted with each quarterly SMR and shall include:

9.7.2.1.1. Date and time of discharge;

9.7.2.1.2. Name, County identification number, and City identification number of the hauler;

9.7.2.1.3. Volume discharged;

9.7.2.1.4. Source(s) of the waste; and

9.7.2.1.5. pH of septage load.

10.REPORTING REQUIREMENTS

10.1. Special Studies, Technical Reports and Additional Monitoring Requirements

10.1.1. Sanitary Sewer Evaluation Survey (SSES). The Permittee shall conduct a SSES to evaluate the condition of its collection system and determine where and what rehabilitation and replacement efforts need to be completed to reduce inflow and infiltration (I/I) and flood risk. As part of the survey, the Permittee shall characterize the existing collection system using available closed circuit CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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television (CCTV) data and employing a system for ranking the condition of pipelines that meets the National Association of Sewer Service Companies (NASCO) or other industry-accepted standards, identify and prioritize collection system deficiencies, provide a schedule of needed long-term and short-term repairs to address system deficiencies and reduce exfiltration, I/I, include a hydraulic analysis of the collection system under estimated dry weather and peak wet weather flow conditions, present findings of the hydraulic analysis on a GIS system map or other database, and identify areas where increases in pipeline size, I&I reduction programs, increases and redundancy in pumping capacity are needed to eliminate any identified hydraulic capacity deficiencies.

The Permittee shall submit a work plan for conducting the survey by April 1, 2025. The survey shall be initiated within 3 years of the permit effective date and a final report summarizing the results of the study shall be submitted by the Regional Water Board in conjunction with the Report of Waste Discharge by January 31, 2028.

10.2. General Monitoring and Reporting Requirements

10.2.1. The Permittee shall comply with all Standard Provisions (Attachment D) related to monitoring, reporting, and recordkeeping.

10.3. Self-Monitoring Reports (SMRs)

10.3.1. The Permittee shall electronically submit SMRs using the State Water Board’s California Integrated Water Quality System (CIWQS) Program website (http://www.waterboards.ca.gov/water_issues/programs/ciwqs/). The CIWQS website will provide additional information for SMR submittal in the event there will be a planned service interruption for electronic submittal. The Permittee shall maintain sufficient staffing and resources to ensure it submits eSMRs that are complete and timely. This includes provisions of training and supervision of individuals (e.g., Permittee personnel or consultant) on how to prepare and submit eSMRs.

10.3.2. The Permittee shall report in the SMR the results for all monitoring specified in this MRP under sections 3 through 9. The Permittee shall submit quarterly SMRs including the results of all required monitoring using U.S. EPA-approved test methods or other test methods specified in this Order. SMRs are to include all new monitoring results obtained since the last SMR was submitted. If the Permittee monitors any pollutant more frequently than required by this Order, the results of this monitoring shall be included in the calculations and reporting of the data submitted in the SMR.

10.3.3. All monitoring results reported shall be supported by the inclusion of the complete analytical report from the laboratory that conducted the analyses.

10.3.4. Monitoring periods and reporting for all required monitoring shall be completed according to the following schedule:

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Table E-8. Monitoring Periods and Reporting Schedule
Sampling
Frequency
Monitoring Period
Begins On… Monitoring Period SMR Due Date
Continuous Permit effective date All
First day of second
calendar month
following the end of
each quarter
(February 1, May 1,
August 1,
November 1)
Daily Permit effective date
(Midnight through 11:59
PM) or any 24-hour period
that reasonably represents
a calendar day for
purposes of sampling
First day of second
calendar month
following the end of
each quarter
(February 1, May 1,
August 1,
November 1)
Weekly
Sunday following
permit effective date
or on permit effective
date if on a Sunday
Sunday through Saturday
First day of second
calendar month
following the end of
each quarter
(February 1, May 1,
August 1,
November 1)
Monthly
First day of calendar
month following
permit effective date
or on permit effective
date if that date is first
day of the month
1st day of calendar month
through last day of
calendar month
First day of second
calendar month
following the end of
each quarter
(February 1, May 1,
August 1,
November 1)
Quarterly
Closest of January 1,
April 1, July 1, or
October 1 following
(or on) permit
effective date
January 1 through March
31 April 1 through June 30
July 1 through September
30 October 1 through
December 31
First day of second
calendar month
following the end of
each quarter
(February 1, May 1,
August 1,
November 1)
Semiannually
Closest of January 1
or July 1 following (or
on) permit effective
date
January 1 through June 30
July 1 through December
31 September 1, each
year
March 1, each year
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Sampling
Frequency
Monitoring Period
Begins On… Monitoring Period SMR Due Date
Annually
January 1 following
(or on) permit
effective date
January 1 through
December 31
March 1, each year
(with annual report)
Once per
permit term Permit effective date All March 1, 2027

10.3.5. Reporting Protocols. The Permittee shall report with each sample result the applicable reported Minimum Level (reported ML, also known as the Reporting Level, or RL) and the current Method Detection Limit (MDL), as determined by the procedure in 40 C.F.R. part 136.

The Permittee shall report the results of analytical determinations for the presence of chemical constituents in a sample using the following reporting protocols:

10.3.5.1. Sample results greater than or equal to the reported ML shall be reported as measured by the laboratory (i.e., the measured chemical concentration in the sample).

10.3.5.2. Sample results less than the reported ML, but greater than or equal to the laboratory’s MDL, shall be reported as “Detected, but Not Quantified,” or DNQ. The estimated chemical concentration of the sample shall also be reported.

For the purposes of data collection, the laboratory shall write the estimated chemical concentration next to DNQ as well as the words “Estimated Concentration” (may be shortened to “Est. Conc.”). The laboratory may, if such information is available, include numerical estimates of the data quality for the reported result. Numerical estimates of data quality may be percent accuracy (± a percentage of the reported value), numerical ranges (low to high), or any other means considered appropriate by the laboratory.

10.3.5.3. Sample results less than the laboratory’s MDL shall be reported as “Not Detected,” or ND.

10.3.5.4. Permittees are to instruct laboratories to establish calibration standards so that the ML value (or its equivalent if there is differential treatment of samples relative to calibration standards) is the lowest calibration standard. At no time is the Permittee to use analytical data derived from extrapolation beyond the lowest point of the calibration curve.

10.3.6. The Permittee shall submit SMRs in accordance with the following requirements:

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ATTACHMENT E – MONITORING AND REPORTING PROGRAM E-28

10.3.6.1. The Permittee shall arrange all reported data in a tabular format. The data shall be summarized to clearly illustrate whether the facility is operating in compliance with interim and/or final effluent limitations. The Permittee is not required to duplicate the submittal of data that is entered in a tabular format within CIWQS. When electronic submittal of data is required and CIWQS does not provide for entry into a tabular format within the system, the Permittee shall electronically submit the data in a tabular format as an attachment.

10.3.6.2. The Permittee shall attach a cover letter to the SMR. The information contained in the cover letter shall clearly identify:

10.3.6.2.1. Facility name and address;

10.3.6.2.2. WDID number;

10.3.6.2.3. Applicable period of monitoring and reporting;

10.3.6.2.4. Violations of the waste discharge requirements (identified violations must include a description of the requirement that was violated and a description of the violation);

10.3.6.2.5. Corrective actions taken or planned; and

10.3.6.2.6. The proposed time schedule for corrective actions.

10.3.6.3. SMRs must be submitted to the Regional Water Board, signed and certified as required by the Standard Provisions (Attachment D), to the CIWQS Program Web site (http://www.waterboards.ca.gov/ciwqs/index.html).

In the event that that an alternate method for submittal of SMRs is required, the Permittee shall submit the SMR electronically via e-mail to [email protected] or on disk (CD or DVD) in Portable Document Format (PDF) file in lieu of paper-sourced documents. The guidelines for electronic submittal of documents can be found on the Regional Water Board website at http://www.waterboards.ca.gov/northcoast.

10.3.6.4. At any time during the term of this permit, the Regional Water Board may notify the Permittee to electronically submit both technical and Self-Monitoring Reports (SMRs) to the State Water Board’s GeoTracker database in searchable Portable Document Format (pdf). In addition, analytical data will be required to be uploaded to the GeoTracker database under a site-specific global identification number that will be assigned to the Permittee. Information on the GeoTracker database is provided on the State Water Board website at:
https://www.waterboards.ca.gov/resources/data_databases/groundwater.shtm l
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10.4. Discharge Monitoring Reports (DMRs)

10.4.1. DMRs are U.S. EPA reporting requirements. The Permittee shall electronically certify and submit DMRs together with SMRs using Electronic Self-Monitoring Reports module eSMR 2.5 or any upgraded version. Electronic DMR submittal shall be in addition to electronic SMR submittal. Information about electronic DMR submittal is available at the DMR website:
(http://www.waterboards.ca.gov/water_issues/programs/discharge_monitoring).

10.5. Other Reports

10.5.1. Special Study Reports and Progress Reports. As specified in the Special Provisions contained in section 6 of the Order and in the MRP, special study and progress reports shall be submitted in accordance with the following reporting requirements.

Table E-9. Reporting Requirements for Special Provisions Reports Order Section Special Provision
Requirement Reporting Requirements
Special Provision 6.3.2.1 Pollutant Minimization Program If required by the Executive Officer
Special Provision 6.3.2.2.5 Pollutant Minimization Program, Annual Facility Report
March 1, annually,
following development of
Pollutant Minimization
Program
Special Provision 6.3.3.4.1 Septage Management Plan Prior to accepting septage Special Provision 6.3.4.5
Adequate Capacity, Technical
Report
Within 120 days of
notification that the Facility
will reach capacity within 4
years
MRP, section 1.6 DMR-QA Study Annually, per State Water Board instructions
MRP section 5.2.1 TRE Work Plan Review
Notification February 1, 2025
MRP section 5.2.1 TRE Work Plan Revisions
Within 90 days of review
notification is revisions are
necessary
MRP section 5.5.2 Detailed TRE Work Plan
Within 30 days of an
accelerated monitoring
test that results in “Fail”
MRP section 9.1 Outfall Evaluation/Inspection
Work Plan June 1, 2024
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ATTACHMENT E – MONITORING AND REPORTING PROGRAM E-30
Order Section Special Provision
Requirement Reporting Requirements
MRP section 9.1 Outfall Evaluation/Inspection
Report April 1, 2026
MRP section 9.2 Biological Survey Work Plan December 1, 2024 MRP section 9.2 Biological Survey Final Report June 1, 2027 MRP section 10.1.1 Sanitary Sewer Evaluation
Survey Work Plan April 1, 2025
MRP section 10.1.1 Sanitary Sewer Evaluation
Survey Final Report November 30, 2027
MRP section 10.5.2 Annual Report March 1, each year
MRP section 10.5.3 Annual Pretreatment Report March 1, each year MRP section 10.6
Spills and Unauthorized
Discharge Reporting
Within 24 hours, verbal
notification
Within 5 days, written
report

10.5.2. Annual Report. The Permittee shall submit an annual report to the Regional Water Board for each calendar year through the CIWQS Program Web site. In the event that a paper copy of the annual report is required, the Permittee shall submit the report to the email address in section 10.3.7.3., above. The report shall be submitted by March 1 of the following year. The report shall, at a minimum, include the following:

10.5.2.1. Where appropriate, tabular and/or graphical summaries of the monitoring data and disposal records from the previous year. If the Permittee monitors any pollutant more frequently than required by this Order, using test procedures approved under 40 C.F.R. part 136 or as specified in this Order, the results of this monitoring shall be included in the calculation and report of the data submitted SMR.

10.5.2.2. A comprehensive discussion of the Facility’s compliance (or lack thereof) with all effluent limitations and other WDRs, and the corrective actions taken or planned, which may be needed to bring the discharge into full compliance with the Order.

10.5.2.3. The names and general responsibilities of all persons employed at the Facility;

10.5.2.4. The names and telephone numbers of persons to contact regarding the Facility for emergency and routine situations; and
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10.5.2.5. A statement certifying when the flow meter(s) and other monitoring instruments and devices were last calibrated, including identification of who performed the calibration.

10.5.2.6. Sludge Handling and Disposal Activity Reporting. The Permittee shall submit, as part of its annual report to the Regional Water Board, a description of the Permittee’s solids handling, disposal and reuse activities over the previous 12 months. At a minimum, the report shall contain:

10.5.2.6.1. Annual sludge production, in dry tons and percent solids;

10.5.2.6.2. Sludge monitoring results;

10.5.2.6.3. A schematic diagram showing sludge handling facilities (e.g., digesters, thickeners, drying beds, etc.), if any and a solids flow diagram;

10.5.2.6.4. Methods of final disposal of sludge:

10.5.2.6.4.1. For any portion of sludge discharged to a sanitary landfill, the Permittee shall provide the volume of sludge transported to the landfill, the names and locations of the facilities receiving sludge, the Regional Water Board’s WDRs order number for the regulated landfill, and the landfill classification.

10.5.2.6.4.2. For any portion of sludge discharged through land application, the Permittee shall provide the volume of biosolids applied, the date and locations where biosolids were applied, the Regional Water Board’s WDRs order number for the regulated discharge, a demonstration that the discharge was conducted in compliance with applicable permits and regulations, and, if applicable, corrective actions taken or planned to bring the discharge into compliance with WDRs.

10.5.2.6.4.3. For any portion of sludge further treated through composting, the Permittee shall provide a summary of the composting process, the volume of sludge composted, and a demonstration and signed certification statement that the composting process and final product met all requirements for Class A biosolids.

10.5.2.6.5. Results of internal or external third-party audits of the Biosolids Management System, including reported program deficiencies and recommendations, required corrective actions, and a schedule to complete corrective actions.

10.5.2.7. Storm Water Reporting. The Permittee shall submit, as part of its annual report to the Regional Water Board, an evaluation of the effectiveness of the Permittee’s BMPs to control the run-on of storm water to the treatment facility site, as well as activities to maintain and upgrade these BMPs.

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ATTACHMENT E – MONITORING AND REPORTING PROGRAM E-32

10.5.2.8. Septage Monitoring and Reporting. The results of septage monitoring shall be provided as follows:

10.5.2.8.1. A narrative description of all preparatory, monitoring, sampling, and analytical testing activities for the septage monitoring program. The narrative shall be sufficiently detailed to verify compliance with waste discharge requirements and this MRP.

10.5.2.8.2. A summary table of all discharges of septage to the Facility. At a minimum, the table shall include; the name, County identification number, and City identification number of each hauler discharging into the Facility over the past calendar year.

10.5.2.8.3. A summary table of analytical results for all samples of septage collected in compliance with waste discharge requirements and this MRP. When directed by the Regional Water Board, the Permittee shall also append analytical reports, chains of custody, and other documentation necessary to confirm the validity of the monitoring samples.

10.5.2.9. DMR-QA Study Report. The Permittee shall submit, as part of its annual report to the Regional Water Board, an electronic copy of the annual DMR-QA study report submitted to the State Water Board, Quality Assurance Program Officer pursuant to section 1.6 of this MRP.

10.5.3. Annual Pretreatment Reporting Requirements. The Permittee shall submit annually a report to the Regional Water Board, with copies to U.S. EPA Region 9 and the State Water Board, describing the Permittee's pretreatment activities over the previous calendar year. In the event that the Permittee is not in compliance with any conditions or requirements of this Order, including noncompliance with pretreatment audit/compliance inspection requirements, then the Permittee shall also include the reasons for noncompliance and state how and when the Permittee shall comply with such conditions and requirements.

An annual report shall be submitted by March 1st of the following year, and include at least the following items:

10.5.3.1. A summary of analytical results from all influent, effluent, and sludge sampling conducted during the reporting period, as specified in sections 3.1.1 (Table E1), 4.1.1 (Table E-3), and 9.6.2 of the MRP. The Permittee shall also report results of any influent, effluent, or sludge monitoring data for nonpriority pollutants which may be causing or contributing to interference, pass-through or adversely impacting sludge quality.

10.5.3.2. A discussion of Upset, Interference, or Pass-Through incidents, if any, at the treatment plant, which the Permittee knows or suspects were caused by industrial users of the POTW or receipt of septage or other incompatible wastes. The discussion shall include the reasons why the incidents occurred, CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
ATTACHMENT E – MONITORING AND REPORTING PROGRAM E-33
the corrective actions taken and, if known, the name and address of, the industrial user(s) responsible. The discussion shall also include a review of the applicable pollutant limitations to determine whether any additional limitations, or changes to existing requirements, may be necessary to prevent Pass-Through, Interference, or noncompliance with sludge disposal requirements.

10.5.3.3. The cumulative number of industrial users that the Permittee has notified regarding Baseline Monitoring Reports and the cumulative number of industrial user responses.

10.5.3.4. An updated list of the Permittee's industrial users including their names and addresses, or a list of deletions and additions keyed to a previously submitted list. The Permittee shall provide a brief explanation for each deletion. The list shall identify the industrial users subject to federal categorical standards by specifying which set(s) of standards are applicable. The list shall indicate which categorical industries, or specific pollutants from each industry, are subject to local limitations that are more stringent than the federal categorical standards. The Permittee shall also list the noncategorical industrial users that are subject only to local discharge limitations. The Permittee shall characterize the compliance status through the year of record of each industrial user by employing the following descriptions:

10.5.3.4.1. complied with Baseline Monitoring Report requirements (where applicable);

10.5.3.4.2. consistently achieved compliance;

10.5.3.4.3. inconsistently achieved compliance;

10.5.3.4.4. significantly violated applicable pretreatment requirements as defined by 40 C.F.R. section 403.8(f)(2)(vii);

10.5.3.4.5. complied with schedule to achieve compliance (include the date final compliance is required);

10.5.3.4.6. did not achieve compliance and not on a compliance schedule; and

10.5.3.4.7. compliance status unknown.

10.5.3.5. A summary of the inspection and sampling activities conducted by the Permittee during the past year to gather information and data regarding the industrial users. The summary shall include:

10.5.3.5.1. The names and addresses of the industrial users subjected to surveillance and an explanation of whether they were inspected, sampled, or both and the frequency of these activities at each user; and
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ATTACHMENT E – MONITORING AND REPORTING PROGRAM E-34

10.5.3.5.2. The conclusions or results from the inspection or sampling of each industrial user.

10.5.3.6. A summary of the compliance and enforcement activities during the past year.

The summary shall include the names and addresses of the industrial users affected by the following actions:

10.5.3.6.1. Warning letters or notices of violation regarding the industrial users' apparent noncompliance with federal categorical standards or local discharge limitations. For each industrial user, identify whether the apparent violation concerned the federal categorical standards or local discharge limitations.

10.5.3.6.2. Administrative orders regarding the industrial users’ noncompliance with federal categorical standards or local discharge limitations. For each industrial user, identify whether the violation concerned the federal categorical standards or local discharge limitations.

10.5.3.6.3. Civil actions regarding the industrial users' noncompliance with federal categorical standards or local discharge limitations. For each industrial user, identify whether the violation concerned the federal categorical standards or local discharge limitations.

10.5.3.6.4. Criminal actions regarding the industrial users’ noncompliance with federal categorical standards or local discharge limitations. For each industrial user, identify whether the violation concerned the federal categorical standards or local discharge limitations.

10.5.3.6.5. Assessment of monetary penalties. For each industrial user identify the amount of the penalties.

10.5.3.6.6. Restriction of flow to the POTW.

10.5.3.6.7. Disconnection from discharge to the POTW.

10.5.3.7. A description of any significant changes in operating the pretreatment program which differ from the information in the Permittee's approved Pretreatment Program including, but not limited to, changes concerning: the program's administrative structure, local industrial discharge limitations, monitoring program or monitoring frequencies, legal authority or enforcement policy, funding mechanisms, resource requirements, or staffing levels.

10.5.3.8. A summary of the annual pretreatment budget, including the cost of pretreatment program functions and equipment purchases.

10.5.3.9. A summary of public participation activities to involve and inform the public CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
ATTACHMENT E – MONITORING AND REPORTING PROGRAM E-35

10.5.3.10. A brief description of any programs the POTW implements to reduce pollutants from nondomestic users that are not classified as Significant Industrial Users (SIUs); and

10.5.3.11. Duplicate signed copies of these Pretreatment Program reports shall be submitted to the North Coast Regional Water Board at
[email protected], U.S. EPA Region 9 at
[email protected], and the State Water Board at the appropriate address below:

STANDARD MAIL FEDEX/UPS/OTHER PRIVATE

CARRIERS
State Water Resources Control Board
Division of Water Quality
c/o Discharge Monitoring Report Processing Center
Post Office Box 100
Sacramento, CA 95812-1000
State Water Resources Control Board
Division of Water Quality
c/o DMR Processing Center
1001 I Street, 15th Floor
Sacramento, CA 95814

10.6. Spill Notification

10.6.1. Spills and Unauthorized Discharges. Information regarding all spills and unauthorized discharges (except SSOs and recycled water) that may endanger health or the environment shall be provided orally to the Regional Water Board13 within 24 hours from the time the Permittee becomes aware of the circumstances and a written report shall also be provided within five (5) days of the time the Permittee becomes aware of the circumstances, in accordance with Section 5.5 of Attachment D.

Information to be provided verbally to the Regional Water Board includes:

10.6.1.1. Name and contact information of caller;

10.6.1.2. Date, time, and location of spill occurrence;

10.6.1.3. Estimates of spill volume, rate of flow, and spill duration, if available and reasonably accurate;
3 The contact number of the Regional Water Board during normal business hours is (707) 576-2220. After normal business hours, spill reporting to the California Governor’s Office of Emergency Services Warning Center (CalOES) will satisfy the 24-hour spill reporting requirement for the Regional Water Board. The contact number for spill reporting for the CalOES is (800) 852-7550.

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10.6.1.4. Surface water bodies impacted, if any;

10.6.1.5. Cause of spill, if known at the time of the notification;

10.6.1.6. Cleanup actions taken or repairs made at the time of the notification; and

10.6.1.7. Responding agencies.

10.6.2. Sanitary Sewer Overflows. Notification and reporting of sanitary sewer overflows is conducted in accordance with the requirements of Order No. WQ 2022-0103-DWQ (Statewide General WDRs for Sanitary Sewer Systems), which is not incorporated herein by reference, and any revisions thereto.

10.6.3. Recycled Water Spills. Notification and reporting of spills and unauthorized discharges of recycled water discharged in or on any waters of the state, as defined in Water Code section 13050, shall be conducted in accordance with the following:

10.6.3.1. Tertiary Recycled Water4

10.6.3.1.1. For unauthorized discharges of 50,000 gallons or more of tertiary recycled water, the Permittee shall immediately notify the Regional Water Board as soon as (a) the Permittee has knowledge of the discharge or probable discharge, (b) notification is possible, and (c) notification can be provided without substantially impeding cleanup or other emergency measures.

10.6.3.1.2. For unauthorized discharges of more than 1,000 gallons, but less than 50,000 gallons of tertiary recycled water, the Permittee shall notify the Regional Water Board as soon as possible, but no longer than 3 days after becoming aware of the discharge.
4 Tertiary Recycled Water means “disinfected tertiary 2.2 recycled water” as defined by DDW or wastewater receiving advanced treatment beyond disinfected tertiary 2.2 recycled water.

CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
ATTACHMENT F – FACT SHEET F-1

FACT SHEET

TABLE OF CONTENTS
Table of Contents.........................................................................................................F-1 Table of Tables ............................................................................................................F-2

1. Permit Information................................................................................................F-3

2. Facility Description ...............................................................................................F-4

2.1. Description of Wastewater and Biosolids Treatment and Controls....................F-4

2.2. Discharge Points and Receiving Waters ...........................................................F-5

2.3. Summary of Existing Requirements and SMR Data..........................................F-6

2.4. Compliance Summary .......................................................................................F-9

2.5. Planned Changes..............................................................................................F-9

3. Applicable Plans, Policies, and Regulations.........................................................F-9

3.1. Legal Authorities................................................................................................F-9

3.2. California Environmental Quality Act (CEQA)..................................................F-10

3.3. State and Federal Laws, Regulations, Policies, and Plans..............................F-10

3.4. Impaired Water Bodies on the CWA section 303(d) List..................................F-14

3.5. Other Plans, Polices and Regulations .............................................................F-14

4. Rationale for Effluent Limitations and Discharge Specifications.........................F-15

4.1. Discharge Prohibitions.....................................................................................F-15

4.2. Technology-Based Effluent Limitations ...........................................................F-18

4.3. Water Quality-Based Effluent Limitations (WQBELs) ......................................F-20

4.4. Final Effluent Limitation Considerations ..........................................................F-37

4.5. Interim Effluent Limitations – Not Applicable ...................................................F-40

4.6. Land Discharge Specifications – Not Applicable .............................................F-40

4.7. Recycling Specifications..................................................................................F-41

4.8. Other Requirements ........................................................................................F-43

5. Rationale for Receiving Water Limitations..........................................................F-45

5.1. Surface Water..................................................................................................F-45

5.2. Groundwater....................................................................................................F-45

6. Rationale for Provisions .....................................................................................F-46

6.1. Federal Standard Provisions ...........................................................................F-46

6.2. Regional Water Board Standard Provisions ....................................................F-46

6.3. Special Provisions ...........................................................................................F-46

7. Rationale for Monitoring and Reporting Requirements ......................................F-50

7.1. Influent Monitoring...........................................................................................F-50

7.2. Effluent Monitoring...........................................................................................F-50

7.3. Whole Effluent Toxicity Testing Requirements ................................................F-51 CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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ATTACHMENT F – FACT SHEET F-2

7.4. Land Discharge Monitoring Requirements – Not Applicable ...........................F-51

7.5. Recycling Monitoring Requirements ................................................................F-52

7.6. Receiving Water Monitoring.............................................................................F-52

7.7. Other Monitoring Requirements.......................................................................F-53

7.8. Special Studies and Additional Monitoring Requirements ...............................F-54

8. Public Participation.............................................................................................F-55

8.1. Notification of Interested Persons....................................................................F-55

8.2. Written Comments...........................................................................................F-55

8.3. Public Hearing .................................................................................................F-56

8.4. Reconsideration of Waste Discharge Requirements .......................................F-56

8.5. Information and Copying .................................................................................F-56

8.6. Register of Interested Persons ........................................................................F-57

8.7. Additional Information......................................................................................F-57

TABLE OF TABLES
Table F-1. Facility Information......................................................................................F-3 Table F-2. Historic Effluent Limitations and Monitoring Data – Discharge Point EFF-001 (April 2017 – January 2023)..................................................................F-7 Table F-3. Basin Plan Beneficial Uses .......................................................................F-11 Table F-4. Ocean Plan Beneficial Uses......................................................................F-12 Table F-5. Summary of Reasonable Potential Analysis Results ................................F-26 Table F-6. Background Seawater Concentrations – Ocean Plan ...............................F-31 Table F-7. Water Quality Objectives – Ocean Plan....................................................F-31 Table F-8. Summary of Chronic Toxicity Results (TUc) .............................................F-33 Attachment F-1. Wastewater Treatment Facility RPA Summary................................F-58 CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
ATTACHMENT F – FACT SHEET F-3

ATTACHMENT F - FACT SHEET
As described in section 2.2 of this Order, the Regional Water Board incorporates this Fact Sheet as findings of the Regional Water Board supporting the issuance of this Order. This Fact Sheet includes the legal requirements and technical rationale that serve as the basis for the requirements of this Order.

This Order has been prepared under a standardized format to accommodate a broad range of discharge requirements for dischargers in California. Only those sections or subsections of this Order that are specifically identified as “not applicable” have been determined not to apply to this Permittee. Sections or subsections of this Order not specifically identified as “not applicable” are fully applicable to this Permittee.

1. PERMIT INFORMATION
The following table summarizes administrative information related to the facility.

Table F-1. Facility Information
WDID 1A84006ODN
Permittee City of Crescent City
Name of Facility Wastewater Treatment Facility
Facility Address 210 Battery Street
Crescent City, CA 95531
Del Norte County
Facility Contact, Title and Phone Eric Wier, City Manager, (707) 464-7483 Authorized Person to Sign and Submit
Reports
Eric Wier, City Manager, (707) 464-7483
Mailing Address 377 J Street
Crescent City, CA 95531
Billing Address SAME
Type of Facility POTW
Major or Minor Facility Major
Threat to Water Quality 1
Complexity A
Pretreatment Program Yes
Recycling Requirements Yes
Facility Permitted Flow 1.86 mgd (average dry weather flow)

6.12 mgd (average wet weather flow)
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ATTACHMENT F – FACT SHEET F-4
Facility Design Flow 1.86 mgd (average dry weather treatment capacity)

6.12 mgd (average wet weather treatment
capacity)
Watershed Smith River Hydrologic Unit
Receiving Water Pacific Ocean
Receiving Water Type Ocean Waters

1.1. The City of Crescent City (hereinafter Permittee) is the owner and operator of the Crescent City Wastewater Treatment Facility (hereinafter Facility), a PubliclyOwned Treatment Works (POTW).

For the purposes of this Order, references to the “discharger” or “permittee” in applicable federal and state laws, regulations, plans, or policy are held to be equivalent to references to the Permittee herein.

1.2. The Facility discharges wastewater to the Pacific Ocean, a water of the United States. The Permittee was previously regulated by Order No. R1- 2017-0002 and National Pollutant Discharge Elimination System (NPDES) Permit No. CA0022756 adopted on February 2, 2017 and expired on March 31, 2022. Attachment B provides a map of the area around the Facility. Attachment C provides a flow schematic of the Facility.

1.3. The Permittee filed a report of waste discharge and submitted an application for reissuance of its waste discharge requirements (WDRs) and NPDES permit on March 31, 2021. The application was deemed complete on November 24, 2021.

1.4. Regulations at 40 C.F.R. section 122.46 limit the duration of NPDES permits to a fixed term not to exceed five years. Accordingly, Table 3 of this Order limits the duration of the discharge authorization. However, pursuant to California Code of Regulations, title 23, section 2235.4, the terms and conditions of an expired permit are automatically continued pending reissuance of the permit if the Permittee complies with all federal NPDES requirements for continuation of expired permits.

2. FACILITY DESCRIPTION
The Permittee owns and operates a municipal wastewater treatment facility (WWTF) and associated wastewater disposal facility that serve a population of approximately 15,372 within Crescent City and the surrounding County Service Area (CSA). The CSA has two sub-areas: the Northwest area to the north of the City and the Bertsch Ocean View area to the east of the City.

2.1. Description of Wastewater and Biosolids Treatment and Controls The Facility treats domestic, commercial, and industrial wastewater and has an average dry weather design treatment capacity of 1.86 mgd and a peak wet CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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weather flow capacity of 6.12 mgd. The Permittee has three significant industrial users, including a cheese factory and two breweries that are covered under local pretreatment permits to discharge to the Facility.

The Permittee and CSA each maintain a separate sanitary sewer collection system within the service area. Flows generated within the CSA are collected and conveyed in the CSA’s satellite collection system to the limits of the Permittee’s system. The Permittee’s system then conveys combined City and Countygenerated flows to the Facility, which is owned and maintained by the Permittee.

The headworks includes a mechanically cleaned screen, a flow-measuring Parshall flume, and a wet well in which five pumps are available to lift the flow to the primary clarifiers. Primary treatment consists of two grit removal tanks followed by two rectangular primary clarifiers. Secondary treatment is provided by operating the rotating biological contactors (RBC) and membrane bioreactor (MBR) in parallel. The RBC system consists of three trains of four-stage, RBCs with a combined surface area of 1.2 million square feet. Flow from the RBCs reach three rectangular secondary clarifiers. Flows from the clarifiers and any flow from the MBR unit that is not used for recycled water use are commingled and disinfected using sodium hypochlorite and dechlorinated using sodium bisulfite prior to discharge to the Pacific Ocean at Discharge Point 001.

The Permittee has the capability of producing tertiary-2.2 recycled water utilizing flow from the MBR and an ultraviolet (UV) light disinfection system that was installed in 2010. The Permittee does not currently have any recycled water use sites, but may produce recycled water in the future if recycled water use sites are identified. The capacity of the recycled water system is 1.2 mgd; however, the MBR can treat up to 1.6 mgd.

Solids handling consists of gravity thickening primary sludge, rotary drum thickening of secondary sludge, and anaerobic digestion of thickened solids. Both digesters are heated and mixed. Digested solids are dewatered using a belt filter press and hauled to a landfill.

2.2. Discharge Points and Receiving Waters
Treated wastewater is discharged at Discharge Point 001 at 41° 44’ 38” N latitude and 124° 12’ 10” W longitude to the Pacific Ocean. The outfall consists of a 24- inch ductile iron pipe that has an effluent conveyance capacity of 11 mgd to 13 mgd, depending on tide conditions. The outfall structure is sloped downward and discharges into a rocky slot in the surf zone adjacent to Battery Point Lighthouse.

Treated wastewater may also be discharged to the recycled water system at Discharge Point 002.

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2.3. Summary of Existing Requirements and SMR Data
Effluent limitations contained in Order No. R1-2017-0002 for discharges from Discharge Points 001 (Monitoring Location EFF-001) and representative monitoring data from the term of Order No. R1-2017-0002 are as follows:

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Table F-2. Historic Effluent Limitations and Monitoring Data – Discharge Point EFF-001 (April 2017 – January 2023)
Parameter Units
Average
Monthly
Effluent
Limitation
Average
Weekly
Effluent
Limitation
Maximum
Daily
Effluent
Limitation
Instantaneous
Maximum
Effluent
Limitation
Highest
Average
Monthly
Discharge
Highest
Average
Weekly
Discharge
Highest
Daily
Discharge
Biochemical
Oxygen Demand
5-day @ 20°C
(BOD5)
mg/L 30 45 -- -- 19.6 43.2 70.6
BOD5 lbs/day1 465 700 -- -- 456 614 1,106
BOD5
%
Removal 85 -- -- -- 842
-- --
Total Suspended
Solids (TSS) mg/L 30 45 -- -- 8.5 26.5 39.3
TSS lbs/day1 465 700 -- -- 173 578 846
TSS %
Removal 85 -- -- -- 912
-- --
Settleable Solids mL/L 1.0 1.5 -- 3.0 0.1 0.9 7.0
Oil and Grease mg/L 25 40 -- 75 5.0 39.9 93.5
Ammonia Nitrogen,
Total (as N) mg/L -- -- 72 180 -- -- 33.3
Turbidity NTU 75 100 225 8.9 13.7 53
pH s.u. -- -- 6.0 - 9.0 -- -- -- 6.8 – 7.7
Copper, Total
Recoverable μg/L -- -- 300 840 -- -- 1,080
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Parameter Units
Average
Monthly
Effluent
Limitation
Average
Weekly
Effluent
Limitation
Maximum
Daily
Effluent
Limitation
Instantaneous
Maximum
Effluent
Limitation
Highest
Average
Monthly
Discharge
Highest
Average
Weekly
Discharge
Highest
Daily
Discharge
Nickel, Total
Recoverable μg/L -- -- 600 1,500 -- -- 116
Total Residual
Chlorine μg/L -- -- 240 1,800 -- -- 15,000
Dieldrin μg/L 0.0012 -- -- -- <0.0048 -- --
TCDD Equivalents μg/L 1.2 x 10-7-- -- -- 9.34 x 10-8-- -- Fecal Coliform
Bacteria
MPN/100
mL 143
-- 434 400 -- -- 1,600
Table Notes

1. Mass-based effluent limitations for BOD5 and TSS are performance-based, as described in the Fact Sheet (Attachment F) of Order No. R1-2017-0002.

2. Represents the lowest observed percent removal.

3. The monthly median concentration shall not exceed 14 MPN/100 mL.

4. No more than 10 percent of samples shall exceed 43 MPN/100 mL.

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2.4. Compliance Summary
On November 16, 2021, the Regional Water Board issued an Invitation to Enter Settlement Prior to Issuance of Formal Administrative Civil Liability Complaint (Invitation to Settle) for 18 violations of effluent limitations for residual chlorine, oil and grease, settleable solids, copper, and fecal coliform organisms in Order No.

R1-2017-0002. The Invitation to Settle assessed a penalty of $45,000 for these violations. On January 19, 2012, the Executive Officer issued a Settlement Agreement and Stipulation for Entry of Administrative Civil Liability (ACL) Order No. R1-2022-0021 that included two additional violations and suspended the ACL of $48,000 pending the completion of a Compliance Project. The Compliance Project consisted of upgrades to the Facility’s SCADA computers and chlorine analyzer systems and was determined to be complete on August 1, 2023.

2.5. Planned Changes
The Permittee may commence discharges of recycled water if any recycled water use sites are identified during the term of this Order. To authorize the use of the Permittee’s recycled water at new recycled water use sites, the Permittee is required to enroll the new recycled water use sites under State Water Resources Control Board Order WQ 2016-0068-DDW or submit an application for modification of this NPDES permit to identify the specific recycled water uses. In addition, the Permittee must complete testing of its UV disinfection system to demonstrate that it meets recycled water requirements in section 60301.230 of title 22 of the CCR.

No other modifications or operational changes that will cause a material change in the volume or quality of discharges from the Facility have been identified for the term of this Order.

3. APPLICABLE PLANS, POLICIES, AND REGULATIONS
The requirements contained in this Order are based on the requirements and authorities described in this section.

3.1. Legal Authorities
This Order serves as WDRs pursuant to article 4, chapter 4, division 7 of the California Water Code (commencing with section 13260). This Order is also issued pursuant to section 402 of the federal Clean Water Act (CWA) and implementing regulations adopted by the U.S. EPA and chapter 5.5, division 7 of the Water Code (commencing with section 13370). It shall serve as an NPDES permit authorizing the Permittee to discharge into waters of the United States at the discharge location described in Table 1 subject to the WDRs in this Order.

This Order also serves as a Master Recycling Permit pursuant to article 4, chapter 7, division 7 of the Water Code (commencing with section 13500).

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3.2. California Environmental Quality Act (CEQA)
Under Water Code section 13389, this action to adopt an NPDES permit is exempt from the provisions of Chapter 3 of CEQA, (commencing with section 21100) of Division 13 of the Public Resources Code. Additionally, the adoption of water recycling requirements for the Facility constitutes permitting of an existing facility that is exempt from the provisions of CEQA pursuant to California Code of Regulations, title 14, section 15301. If at any time the Permittee proposes to expand its recycled water system to include use sites, the Permittee will be the lead agency under CEQA.

3.3. State and Federal Laws, Regulations, Policies, and Plans

3.3.1. Water Quality Control Plan
The Regional Water Board adopted a Water Quality Control Plan for the North Coast Region (hereinafter Basin Plan) that designates beneficial uses, establishes water quality objectives, and contains implementation programs and policies to achieve those objectives for all waters addressed through the plan. In addition, the Basin Plan implements State Water Board Resolution No. 88-63, which establishes state policy that all waters, with certain exceptions, should be considered suitable or potentially suitable for municipal or domestic supply. With high concentrations of total dissolved solids, ocean waters meet an exception to State Water Board Resolution No. 88-63; and therefore, the MUN designation is not applicable to the ocean receiving water for this Permittee. Requirements in this Order implement the Basin Plan.

Beneficial uses applicable to the Pacific Ocean are as follows:

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Table F-3. Basin Plan Beneficial Uses
Discharge Point Receiving Water
Name Beneficial Use(s)
001 Pacific Ocean Existing:

Navigation (NAV);
Water contact recreation (REC-1);
Non-contact water recreation (REC-2);
Commercial and sport fishing (COMM);
Wildlife habitat (WILD);
Rare, threatened, or endangered species
(RARE);
Marine habitat (MAR);
Migration of aquatic organisms (MIGR);
Spawning, reproduction, and/or early
development (SPAWN);
Shellfish harvesting (SHELL); and
Aquaculture (AQUA).

Potential:

Industrial water supply (IND);
Industrial process supply (PRO); and
Preservation of Areas of Special Biological
Significance (ASBS).
002 Groundwater Existing:

Municipal and domestic supply (MUN);
Agricultural supply (AGR);
Industrial service supply (IND); and
Native American Culture (CUL).

Potential:

Industrial Process Supply (PRO); and
Aquaculture (AQUA).

3.3.2. Thermal Plan
The State Water Board adopted the Water Quality Control Plan for Control of Temperature in the Coastal and Interstate Waters and Enclosed Bays and Estuaries of California (Thermal Plan) on January 7, 1971, and amended this plan on September 18, 1975. This plan contains temperature objectives for coastal waters. The Permittee does not discharge thermal waste; therefore, the Order does not include effluent limitations for temperature in response to the requirements of the Thermal Plan.

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3.3.3. California Ocean Plan
The State Water Board adopted the Water Quality Control Plan for Ocean Waters of California, California Ocean Plan (Ocean Plan) in 1972 and amended it in 1978, 1983, 1988, 1990, 1997, 2000, 2005, 2009, 2012, and 2019. The State Water Board adopted the latest amendment on August 7, 2018, and it became effective on February 4, 2019. The Ocean Plan is applicable, in its entirety, to point source discharges to the ocean. The Ocean Plan identifies beneficial uses of ocean waters of the state to be protected as summarized below:

Table F-4. Ocean Plan Beneficial Uses
Discharge
Point
Receiving
Water Beneficial Uses
001 Pacific Ocean
Industrial water supply;
Water contact and non-contact recreation, including
aesthetic enjoyment;
Navigation;
Commercial and sport fishing;
Mariculture;
Preservation and enhancement of designated Areas of
Special Biological Significance (ASBS);
Rare and endangered species;
Marine habitat;
Fish spawning; and
Shellfish harvesting
In order to protect the beneficial uses, the Ocean Plan establishes water quality objectives and a program of implementation. Requirements of this Order implement the Ocean Plan.

3.3.4. Compliance Schedules and Interim Requirements
The State Water Board adopted Resolution No. 2008-0025 on April 15, 2008, titled Policy for Compliance Schedules in National Pollutant Discharge Elimination System Permits, which includes compliance schedule policies for pollutants that are not addressed by the Policy for Implementation of Toxics Standards for Inland Surface Waters, Enclosed Bays, and Estuaries of California (State Implementation Policy or SIP). This Policy became effective on August 27, 2008.

This Order does not include any compliance schedules or interim effluent limitations.

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3.3.5. Antidegradation Policy
Federal regulation 40 C.F.R. section 131.12 requires that the state water quality standards include an antidegradation policy consistent with the federal policy.

The State Water Board established California’s antidegradation policy in State Water Board Resolution 68-16 (“Statement of Policy with Respect to Maintaining High Quality of Waters in California”). Resolution 68-16 is deemed to incorporate the federal antidegradation policy where the federal policy applies under federal law. Resolution 68-16 requires that existing water quality be maintained unless degradation is justified based on specific findings. The Regional Water Board’s Basin Plan implements, and incorporates by reference, both the state and federal antidegradation policies. The permitted discharge must be consistent with the antidegradation provision of section 131.12 and State Water Board Resolution 68-16.

3.3.6. Anti-Backsliding Requirements
Sections 402(o) and 303(d)(4) of the CWA and federal regulations at 40 C.F.R. section 122.44(l) restrict backsliding in NPDES permits. These anti-backsliding provisions require that effluent limitations in a reissued permit must be as stringent as those in the previous permit, with some exceptions in which limitations may be relaxed.

3.3.7. Endangered Species Act Requirements
This Order does not authorize any act that results in the taking of a threatened or endangered species or any act that is now prohibited, or becomes prohibited in the future, under either the California Endangered Species Act (Fish and Game Code, §§ 2050 to 2097) or the Federal Endangered Species Act (16 U.S.C.A. §§ 1531 to 1544). This Order requires compliance with effluent limits, receiving water limits, and other requirements to protect the beneficial uses of waters of the state, including protecting rare and endangered species. The Permittee is responsible for meeting all requirements of the applicable Endangered Species Act.

3.3.8. Sewage Sludge and Biosolids
This Order does not authorize any act that results in violation of requirements administered by U.S. EPA to implement 40 C.F.R. Part 503, Standards for the Use or Disposal of Sewage Sludge. These standards regulate the final use or disposal of sewage sludge that is generated during the treatment of domestic sewage in a municipal wastewater treatment facility. The Permittee is responsible for meeting all applicable requirements of 40 C.F.R. Part 503 that are under U.S. EPA’s enforcement authority.

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3.4. Impaired Water Bodies on the CWA section 303(d) List Section 303(d) of the federal CWA requires states to identify waterbodies that do not meet water quality standards and are not supporting their beneficial uses after implementation of technology-based effluent limitations on point sources. Each state must submit an updated list, the 303(d) List of Impaired Waterbodies every two years. In addition to identifying the waterbodies that are not supporting beneficial uses, the 303(d) list also identifies the pollutant or stressor causing impairment and establishes a schedule for developing a control plan to address the impairment. The CWA requires development of a total maximum daily load (TMDL) or alternate program of implementation for each 303(d) listed pollutant and water body to remedy the impairment. TMDLs establish the maximum quantity of a given pollutant that can be added to a water body from all sources without exceeding the applicable water quality standard for that pollutant and determine wasteload allocations (the portion of a TMDL allocated to existing and future point sources) and load allocations (the portion of a TMDL attributed to existing and future nonpoint sources).

On June 9, 2021, the U.S. EPA provided final approval of the 2018 303(d) list of impaired water bodies prepared by the state. The Pacific Ocean, in the vicinity of the discharge, is not listed as an impaired waterbody on the 303(d) list.

3.5. Other Plans, Polices and Regulations

3.5.1. On December 6, 2022, the State Water Board adopted State Water Board Order No. WQ 2022-0103-DWQ, Statewide Waste Discharge Requirements, General Order for Sanitary Sewer Systems (Sanitary Sewer General Order). This Order became effective on June 5, 2023, and replaced Order No. 2006-0003-DWQ and all associated amendments thereof. Order No. 2022-0103-DWQ requires that all public agencies that currently own or operate sanitary sewer systems electronically certify the Continuation of Existing Coverage form in the CIWQS Sanitary Sewer System Database within 60 days prior to the effective date of the Sanitary Sewer General Order. The Permittee certified their existing coverage and is subject to the requirements of Order No. 2022-0103-DWQ and any future revisions thereto for operation of its wastewater collection system.

3.5.2. All areas within the Facility drain to the headworks. State Water Board Water Quality Order No. 2014-0057-DWQ, NPDES General Permit No. CAS000001, General Permit for Storm Water Discharges Associated with Industrial Activities (Industrial Storm Water General Permit) does not require facilities to obtain coverage if storm water is captured and treated and/or disposed of within the facility’s NPDES permitted process wastewater or if storm water is disposed of evaporation ponds, percolation ponds, or combined sewer systems. Therefore, coverage under the Industrial Storm Water General Permit is not required for this Facility.

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4. RATIONALE FOR EFFLUENT LIMITATIONS AND DISCHARGE

SPECIFICATIONS
The CWA requires point source dischargers to control the amount of conventional, non-conventional, and toxic pollutants that are discharged into the waters of the United States. The control of pollutants discharged is established through effluent limitations and other requirements in NPDES permits.

There are two principal bases for effluent limitations in the Code of Federal Regulations: 40 C.F.R. section 122.44(a) requires that permits include applicable technology-based limitations and standards; and 40 C.F.R. section 122.44(d) requires that permits include water quality-based effluent limitations (WQBELs) to attain and maintain applicable numeric and narrative water quality criteria to protect the beneficial uses of the receiving water where a reasonable potential to exceed those criteria exists.

4.1. Discharge Prohibitions

4.1.1. Discharge Prohibition 3.1. The discharge of any waste not disclosed by the Permittee or not within the reasonable contemplation of the Regional Water Board is prohibited.

This prohibition has been retained from Order No. R1-2017-0002 and is based on the Basin Plan and State Water Board Order No. WQO 2002-0012 regarding the petition of WDRs Order No. 01-072 for the East Bay Municipal Utility District and Bay Area Clean Water Agencies. In State Water Board Order No. WQO 2002-0012, the State Water Board found that this prohibition is acceptable in orders, but should be interpreted to apply only to constituents that are either not disclosed by the Permittee, or are not reasonably anticipated to be present in the discharge but have not been disclosed by the Permittee. It specifically. does not apply to constituents in the discharge that do not have “reasonable potential” to exceed water quality objectives.

The State Water Board has stated that the only pollutants not covered by this prohibition are those which were “disclosed to the permitting authority and…can be reasonably contemplated.” [In re the Petition of East Bay Municipal Utilities District et al., (State Water Board, 2002) Order No. WQO 2002-0012, p. 24]. In that Order, the State Water Board cited a case which held the Permittee is liable for the discharge of pollutants “not within the reasonable contemplation of the permitting authority…whether spills or otherwise…” [Piney Run Preservation Assn. v. County Commissioners of Carroll County, Maryland (4th Cir. 2001) 268 F. 3d 255, 268.] Thus the State Water Board authority provides that, to be permissible, the constituent discharged (1) must have been disclosed by the Permittee and (2) can be reasonably contemplated by the Regional Water Board.

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Whether or not the Permittee reasonably contemplates the discharge of a constituent is not relevant. What matters is whether the Permittee disclosed the constituent to the Regional Water Board or whether the presence of the pollutant in the discharge can otherwise be reasonably contemplated by the Regional Water Board at the time of Order adoption.

4.1.2. Discharge Prohibition 3.2. Creation of pollution, contamination, or nuisance, as defined by section 13050 of the Water Code is prohibited.

This prohibition has been retained from Order No. R1-2017-0002 and is based on section 13050 of the Water Code and section 5411 of the California Health and Safety Code.

4.1.3. Discharge Prohibition 3.3. The discharge of sludge or digester supernatant is prohibited, except as authorized under section 6.3.4.2 of this Order (Sludge Disposal and Handling Requirements).

This prohibition has been retained from Order No. R1-2017-0002 and is based on restrictions on the disposal of sewage sludge found in federal regulations [40 C.F.R. part 503 (Biosolids), Part 527, and Part 258] and title 27 of the CCR.

4.1.4. Discharge Prohibition 3.4. The discharge or recycling use of untreated or partially treated waste (receiving a lower level of treatment than described in section 2.1 of the Fact Sheet) from anywhere within the collection, treatment, or disposal systems is prohibited, except as provided for in Attachment D, Standard Provisions 1.7 (Bypass) and 1.8 (Upset).

This prohibition has been retained from Order No. R1-2017-0002 and is based on the Basin Plan to protect the beneficial uses of the receiving water from unpermitted discharges, and the intent of the Water Code sections 13260 through 13264 relating to the discharge of waste to waters of the state without filing for and being issued an Order. This prohibition applies to spills not related to sanitary sewer overflows (SSOs) and other unauthorized discharges of wastewater within the collection, treatment, and disposal facilities. The discharge of untreated or partially treated wastewater from the collection, treatment, or disposal facility represents an unauthorized bypass pursuant to 40 C.F.R. section 122.41(m) or an unauthorized discharge which poses a threat to human health and/or aquatic life, and therefore is explicitly prohibited by this Order.

4.1.5. Discharge Prohibition 3.5. The discharge of waste to land that is not owned by the Permittee, governed by City ordinance, or under agreement to use by the Permittee, or for which the Permittee has explicitly permitted such use, is prohibited, except for use for non-structural fire suppression as provided in title 22, sections 60307(a) and 60307(b) of the CCR.

This prohibition is retained from Order No. R1-2017-0002 with minor modifications. Land used for the application of wastewater must be owned by CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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the Permittee or be under the control of the Permittee by contract so that the Permittee maintains a means for ultimate disposal of treated wastewater.

4.1.6. Discharge Prohibition 3.6. The discharge of waste at any point not described in Finding 2.2 of the Fact Sheet or authorized by a permit issued by the State Water Board or another Regional Water Board is prohibited.

This prohibition is retained from Order No. R1-2017-0002. This prohibition is a general prohibition that allows the Permittee to discharge waste only in accordance with WDRs. It is based on sections 301 and 402 of the federal CWA and section 13263 of the Water Code.

4.1.7. Prohibition 3.7. The average dry weather flow of waste through the Facility shall not exceed 1.86 mgd, measured daily and averaged over a calendar month. The peak daily wet weather flow of waste through the Facility shall not exceed 6.12 mgd, measured daily. Compliance with this prohibition shall be determined as defined in sections 7.10 and 7.11 of this Order.

The prohibition is retained from Order No. R1-2017-0002. These prohibitions are based on the average dry weather and peak wet weather discharge treatment capacity of the Facility. Exceedance of this capacity on a daily basis may result in effluent violations and/or the need to by-pass untreated effluent blended with treated effluent, which is prohibited.

4.1.8. Prohibition 3.8. The discharge of any radiological, chemical, or biological warfare agent or high-level radioactive waste into waters of the state is prohibited.

This prohibition is retained from Order No. R1-2017-0002 and is based on the discharge prohibitions contained in section III.I of the Ocean Plan and section 13375 of the Water Code.

4.1.9. Prohibition 3.9. The discharge of sludge directly into the ocean or into a waste stream that discharges to the ocean is prohibited.

This prohibition is retained from Order No. R1-2017-0002 and is based on the discharge prohibitions contained in section III.I of the 2019 Ocean Plan.

4.1.10. Prohibition 3.10. The by-passing of untreated wastes containing concentrations of pollutants in excess of those of Ocean Plan Tables 3 and 4 (2019) is prohibited.

This prohibition is retained from Order No. R1-2017-0002 and is based on the discharge prohibitions contained in section III.I. of the Ocean Plan.

4.1.11. Prohibition 3.11. The acceptance of septage to a location other than an approved septage receiving station is prohibited.

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This prohibition is retained from Order No. R1-2017-0002 and is necessary to ensure that the Permittee is aware of all discharges of septage into the treatment system so that pollutants associated with domestic septage do not pass through or interfere with the operation or performance of the Facility.

4.2. Technology-Based Effluent Limitations

4.2.1. Scope and Authority
Section 301(b) of the CWA and implementing U.S. EPA permit regulations at 40 C.F.R. section 122.44 require that permits include conditions meeting applicable technology-based requirements at a minimum, and any more stringent effluent limitations necessary to meet applicable water quality standards. The discharge authorized by this Order must meet minimum federal technology-based requirements based on Secondary Treatment Standards at 40 C.F.R. part 133 and/or Best Professional Judgment (BPJ) in accordance with 40 C.F.R. section 125.3.

In addition, 40 C.F.R. section 122.45(d)(2) states that technology-based permit limits shall be stated as average weekly and average monthly discharge limitations, unless impracticable, for POTWs. 40 C.F.R. section 103.102 provides detailed specifications for establishing effluent limitations for the technology-based constituents, BOD5, TSS, and pH. Effluent limitations for BOD5, TSS, and pH in section 4.1, Effluent Limitations, of this Order were established as required by 40 C.F.R. section 103.102 and have been retained in this Order.

Regulations promulgated in 40 C.F.R. section 125.3(a)(1) require technologybased effluent limitations for municipal dischargers to be placed in NPDES permits based on Secondary Treatment Standards or Equivalent to Secondary Treatment Standards.

The Federal Water Pollution Control Act Amendments of 1972 (PL 92-500) established the minimum performance requirements for POTWs [defined in section 304(d)(1)]. Section 301(b)(1)(B) of that Act requires that such treatment works must, as a minimum, meet effluent limitations based on secondary treatment as defined by the U.S. EPA Administrator.

Based on this statutory requirement, U.S. EPA developed secondary treatment regulations, which are specified in 40 C.F.R. part 133. These technology-based regulations apply to all municipal wastewater treatment plants and identify the minimum level of effluent quality attainable by secondary treatment in terms of BOD5, TSS, and pH, as follows:

4.2.1.1. BOD5 and TSS

4.2.1.1.1. The 30-day average shall not exceed 30 mg/L.

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4.2.1.1.2. The 7-day average shall not exceed 45 mg/L.

4.2.1.1.3. The 30-day average percent removal shall not be less than 85%.

4.2.1.2. pH

4.2.1.2.1. The pH shall be maintained within the limits of 6.0 to 9.0.

4.2.1.2.2. The effluent limitation for pH is also required to meet the water quality objective for hydrogen ion concentration (pH) contained in the Basin Plan, Table 3-1.

In addition, 40 C.F.R. section 122.45(f) requires the establishment of massbased effluent limitations for all pollutants limited in Orders, except for 1) pH, temperature, radiation, or other pollutants, which cannot be appropriately expressed by mass, 2) when applicable standards and limitations are expressed in terms of other units of measure.

4.2.2. Applicable Technology-Based Effluent Limitations

4.2.2.1. Secondary Treatment Standards (BOD5, TSS, and pH). As described above, the secondary treatment standards at 40 C.F.R. part 133 establish the minimum level of effluent quality attainable by secondary treatment in terms of BOD5, TSS, and pH. Numeric effluent limitations for BOD5, TSS, and pH, including the percent removal requirement for TSS, are retained from Order No. R1-2017-0002 and reflect the secondary treatment standards at 40 C.F.R. part 133.

4.2.2.2. Ocean Plan Table 4 Effluent Limitations (Ammonia, Oil and Grease, TSS, Settleable Solids, Turbidity, and pH). The State Water Board, in Table 4 of the Ocean Plan, has established technology-based requirements for oil and grease, TSS, settleable solids, turbidity, and pH. Table 4 effluent limitations apply to POTWs, and also to industrial discharges for which Effluent Limitations Guidelines have not been established pursuant to Sections 301, 302, 304, or 306 of the federal CWA. Compliance with Table 4 effluent limitations shall be the minimum level of treatment acceptable under the Ocean Plan, and shall define reasonable treatment and waste control technology. The Facility is a POTW; therefore, technology-based limitations contained in Table 4 of the Ocean Plan are applicable to the Permittee.

Consistent with Order No. R1-2017-0002, this Order includes effluent limitations for oil and grease, settleable solids, turbidity, and pH based on Table 4 of the Ocean Plan.

The percent removal requirements for TSS in the secondary treatment requirements (i.e., 85 percent) are more stringent than the percent removal requirements in Table 4 of the Ocean Plan (i.e., 75 percent); therefore, consistent with Order No. R1-2017-0002, this Order includes percent removal CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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requirements for TSS based on the secondary treatment standards at 40 C.F.R. part 133.

4.2.2.3. Mass-Based Effluent Limitations. Federal regulations at 40 C.F.R. section 122.45(f) require that, except under certain conditions, all permit limits, standards, or prohibitions be expressed in terms of mass units. Among the conditions exempting the application of mass-based limitations is section 40 C.F.R. section 122.45(f)(1)(i), which states “for pH, temperature, and radiation, or other pollutants which cannot appropriately be expressed by mass” and 40 C.F.R. section 122.45(f)(1)(ii), which states “when applicable standards and limitations are expressed in terms of other units of measure.” This Order does not include mass-based effluent limitations for the following pollutants pursuant to the exception in 40 C.F.R, section 122.45(f)(1)(i) and (ii):

4.2.2.3.1. Settleable solids, turbidity, and pH because these parameters cannot appropriately be expressed by mass; and

4.2.2.3.2. Oil and grease, because the applicable standards for oil and grease in Table 4 of the Ocean Plan are expressed in terms of concentration.

4.2.2.3.3. BOD5 and TSS, because these two parameters are expressed in terms of concentration and percent removal; and

4.3. Water Quality-Based Effluent Limitations (WQBELs)

4.3.1. Scope and Authority
CWA Section 301(b) and 40 C.F.R. section 122.44(d) require that permits include limitations more stringent than applicable federal technology-based requirements where necessary to achieve applicable water quality standards.

Section 122.44(d)(1)(i) of 40 C.F.R. requires that permits include effluent limitations for all pollutants that are or may be discharged at levels that have the reasonable potential to cause or contribute to an exceedance of a water quality standard, including numeric and narrative objectives within a standard. Where reasonable potential has been established for a pollutant, but there is no numeric criterion or objective for the pollutant, water quality-based effluent limitations (WQBELs) must be established using: (1) U.S. EPA criteria guidance under CWA section 304(a), supplemented where necessary by other relevant information; (2) an indicator parameter for the pollutant of concern; or (3) a calculated numeric water quality criterion, such as a proposed state criterion or policy interpreting the state’s narrative criterion, supplemented with other relevant information, as provided in section 122.44(d)(1)(vi).

The process for determining reasonable potential and calculating WQBELs when necessary is intended to protect the designated uses of the receiving CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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water as specified in the Basin Plan, and achieve applicable water quality objectives and criteria that are contained in other state plans and policies, or any applicable water quality criteria contained in the Ocean Plan.

4.3.2. Applicable Beneficial Uses and Water Quality Criteria and Objectives

4.3.2.1. Beneficial Uses. Beneficial use designations for receiving waters for discharges from the Facility are presented in section 3.3.1 and 3.3.3 of this Fact Sheet.

4.3.2.2. Ocean Plan Water Quality Objectives. Water quality criteria applicable to ocean waters of the Region are established by the Ocean Plan, which includes general provisions and water quality objectives for bacterial characteristics, physical characteristics, chemical characteristics, biological characteristics, and radioactivity. These water quality objectives from the Ocean Plan are incorporated as receiving water limitations in section 5.1 of the Order. Table 3 of the Ocean Plan contains numeric water quality objectives for 83 toxic pollutants for the protection of marine aquatic life and human health. Pursuant to NPDES regulations at 40 C.F.R. section 122.44(d)(1), and in accordance with procedures established by the Ocean Plan, the Regional Water Board has performed an Ocean Plan reasonable potential analysis (RPA) to determine the need for effluent limitations for the Table 3 toxic pollutants.

4.3.2.3. Minimum Initial Dilution. In accordance with the Ocean Plan, WQBELs reflect the minimum initial dilution of the effluent as it reaches the receiving water. The minimum initial dilution can be estimated by experimental observation (e.g., dye studies, etc.) and/or computer simulation. The Ocean Plan requires that dilution estimates be based on the assumption of no currents; unless an alternative method of calculating dilution is found to be acceptable to the Regional Water Board. For the purpose of this and previous Orders, minimum initial dilution was determined with a dye study in 1982 and a mixing model in 2004 to conservatively estimate dilution in the rocky slot where the Permittee’s ocean outfall discharges.

The dilution evaluation is described in a March 26, 2004, Brown and Caldwell Technical Memorandum with the subject line “Slot Dilution Model”. This Technical Memorandum describes a flushing model developed by Brown and Caldwell to evaluate and determine dilution in the rocky slot by modeling mixing that results from wave action within the rocky slot. The model also considered median wind velocities to estimate a re-entrainment factor for previously mixed effluent that could wash back into the slot. Water within the slot was assumed to be completely mixed by the action of breaking waves.

The Technical Memorandum also summarizes the results of the model and dilution ratio calculations and provides calibration against the results of the 1982 dye study to verify the adequacy of the model. The results of this evaluation were used to reduce the dilution ratio from 50:1 (the dilution ratio CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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granted in Orders prior to 2006) to 29:1. The 29:1 dilution ratio is conservatively based on a maximum daily flow of 9.9 mgd, the Permittee’s projected 2027 maximum daily design flow. Between May 2011 and September 2016, the Permittee’s maximum daily flow was 6.2 mgd, calculated as an average over a 24-hour period. The maximum daily flow is not expected to increase above 9.9 mgd by 2027 based on population estimates. The Regional Water Board finds that the 29:1 dilution ratio is valid for use in this Order because the Permittee’s discharge is well under the flows used for estimating the dilution ratio.

This Order uses a minimum initial dilution of 29:1 (i.e., 29 parts ocean water to 1 part effluent) for its reasonable potential analysis and effluent limitation calculations.

4.3.3. Determining the Need for WQBELs
NPDES regulations at 40 C.F.R. section 122.44 (d) require effluent limitations to control all pollutants which are or may be discharged at a level which will cause, have the reasonable potential to cause, or contribute to an excursion above any state water quality standard.

4.3.3.1. Ocean Plan Reasonable Potential Analysis (RPA). Procedures for performing an RPA for ocean dischargers are described in Section III.C. and Appendix VI of the Ocean Plan. In general, the procedure is a statistical method that projects an effluent data set while taking into account the averaging period of water quality objectives, the long term variability of pollutants in the effluent, limitations associated with sparse data sets, and uncertainty associated with censored data sets. The procedure assumes a lognormal distribution of the effluent data set, and compares the 95th percentile concentration at 95 percent confidence of each Table 3 pollutant, accounting for dilution, to the applicable water quality criterion. The RPA results in one of three following endpoints.

Endpoint 1 – There is “reasonable potential,” and a WQBEL and monitoring are required.

Endpoint 2 – There is “no reasonable potential.” WQBELs are not required, and monitoring is required at the discretion of the Regional Water Board.

Endpoint 3 – The Ocean Plan RPA is inconclusive. Existing WQBELs are retained, and monitoring is required.

The State Water Resources Control Board has developed a reasonable potential calculator, which is available at on the State Water Board’s webpage (http://www.waterboards.ca.gov/plnspols/docs/oplans/rpcalc.zip). The calculator (RPcalc 2.2) was used in conducting the RPA and considers several pathways in the determination of reasonable potential.

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4.3.3.1.1. First Path
If available information about the receiving water or the discharge supports a finding of reasonable potential without analysis of effluent data, the Regional Water Board may decide that WQBELs are necessary after a review of such information. Such information may include: the facility or discharge type, solids loading, lack of dilution, history of compliance problems, potential toxic effects, fish tissue data, 303(d) status of the receiving water, or the presence of threatened or endangered species or their critical habitat, or other information.

4.3.3.1.2. Second Path
If any pollutant concentration, adjusted to account for dilution, is greater than the most stringent applicable water quality objective, there is reasonable potential for that pollutant.

4.3.3.1.3. Third Path
If the effluent data contains three or more detected and quantified values (i.e., values that are at or above the ML), and all values in the data set are at or above the ML, a parametric RPA is conducted to project the range of possible effluent values. The 95th percentile concentration is determined at 95 percent confidence for each pollutant and compared to the most stringent applicable water quality objective to determine reasonable potential. A parametric analysis assumes that the range of possible effluent values is distributed log normally. If the 95th percentile value is greater than the most stringent applicable water quality objective, there is reasonable potential for that pollutant.

4.3.3.1.4. Fourth Path
If the effluent data contains three or more detected and quantified values (i.e., values that are at or above the ML), but at least one value in the data set is less than the ML, a parametric RPA is conducted according to the following steps.

4.3.3.1.4.1. If the number of censored values (those expressed as a “less than” value) account for less than 80 percent of the total number of effluent values, calculate the ML (the mean of the natural log of transformed data) and SL (the standard deviation of the natural log of transformed data) and conduct a parametric RPA, as described above for the Third Path.

4.3.3.1.4.2. If the number of censored values accounts for 80 percent or more of the total number of effluent values, conduct a non-parametric RPA, as described below for the Fifth Path. (A non-parametric analysis becomes necessary when the effluent data is limited, and no assumptions can be made regarding its possible distribution.)
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4.3.3.1.5. Fifth Path
A non-parametric RPA is conducted when the effluent data set contains less than three detected and quantified values, or when the effluent data set contains three or more detected and quantified values but the number of censored values accounts for 80 percent or more of the total number of effluent values. A non-parametric analysis is conducted by ordering the data, comparing each result to the applicable water quality objective, and accounting for ties. The sample number is reduced by one for each tie, when the dilution adjusted method detection limit (MDL) is greater than the water quality objective. If the adjusted sample number, after accounting for ties, is greater than 15, the pollutant has no reasonable potential to exceed the water quality objective. If the sample number is 15 or less, the RPA is inconclusive, monitoring is required, and any existing effluent limitations in the expiring permit are retained.

4.3.3.2. Reasonable Potential Determination
The RPA for the effluent was conducted using effluent monitoring data generated from annual monitoring events for all Ocean Plan Table 3 parameters in October 2018, October 2019, October 2020, October 2021, and October 2022 and from routine monitoring events conducted between January 2018 through February 2023 for ammonia, copper, nickel, chlorine residual, dieldrin, TCDD equivalents, ammonia, and chronic toxicity as required by the Monitoring and Reporting Program for Order No. R1-2017-0002. Results from the RPA have been used to determine the need for effluent limitations for Table 3 parameters given in the Ocean Plan.

For the RPA conducted for this permit renewal, pollutant concentrations were adjusted to account for the calculated initial dilution of 29 parts seawater per part wastewater. The adjustment for dilution is consistent with previous orders for this Facility.

The table below identifies the RPA endpoint for each Table 3 parameter detected in the effluent and shows the analysis reached an Endpoint 3 for most of the parameters analyzed. An Endpoint 3 RPA is inconclusive and results when a majority of the effluent data is reported as ND (not detected).

In these circumstances, the Regional Water Board views the “inconclusive” result as an indication of no concern for a particular pollutant; however, additional monitoring will be required for those parameters during the term of the permit.

The RPA conducted for the Facility demonstrated reasonable potential (Endpoint 1) for discharges from the Facility to cause or contribute to exceedances of applicable water quality criteria for ammonia, chlorine residual, copper, DDT, endosulfan, endrin, heptachlor, and silver.

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Order No. R1-2017-0002 established effluent limitations for dieldrin based on the numeric water quality criteria from the Ocean Plan. As shown in the table below, the RPA conducted for the Facility was inconclusive (Endpoint 3) for dieldrin. For RPA results of Endpoint 3, the Ocean Plan specifies that existing effluent limitations for the pollutant shall remain in the permit. Therefore, this Order retains the effluent limitations for dieldrin from Order No. R1-2017- 0002.

The following table summarizes the RPA for each priority pollutant that was reported in detectable concentrations in the effluent. The MECs, most stringent water quality objectives (WQO), and background concentrations (B) used in the RPA are presented, along with the RPA results for each toxic pollutant analyzed. No other pollutants with applicable numeric water quality criteria from the Ocean Plan were measured above detectable concentrations or analyzed for during the monitoring events conducted by the Permittee.

Attachment F-1 to this Order summarizes the RPA for all priority toxic pollutants with water quality criteria/objectives that are applicable to the Pacific Ocean.

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Table F-5. Summary of Reasonable Potential Analysis Results Table 3
Pollutant
Most
Stringent
WQO (µg/L)
No. of
Samples
No. of NonDetects
Background
Conc.
(µg/L)
Cs1
Max Effluent
Conc.
(µg/L)
Ce
Calculated
Max
Conc.
(µg/L)2
X-obs
RPA Results,
Comment3
Arsenic 8 12 7 3 82.6 5.6533 Endpoint 2
Cadmium 1 12 7 0 15.5 0.5167 Endpoint 2
Chromium VI 2 5 3 0 6.3 0.21 Endpoint 3
Copper 3 71 2 2 1080 37.9333 Endpoint 1
Nickel 5 71 8 0 116 3.8667 Endpoint 2
Silver 0.7 12 7 0.16 139 4.7880 Endpoint 1
Zinc 20 12 0 8 311 18.1000 Endpoint 2
Cyanide 1 11 10 0 1.2 0.04 Endpoint 3
Total Chlorine
Residual 2 1855 1849 0 15000 500 Endpoint 1
Ammonia (as N) 600 538 0 0 33300 1110 Endpoint 1
Endosulfan 0.009 12 10 0 0.32 0.0107 Endpoint 1
Endrin 0.002 12 10 0 2.84 0.0947 Endpoint 1
Antimony 1200 5 4 0 21 0.700 Endpoint 3
Chromium (III) 190000 5 4 0 1.75 0.0583 Endpoint 3
Toluene 85000 5 0 0 7.69 0.2563 Endpoint 2
Bis(2-
ethlyhexyl)
Phthalate

3.5 12 9 0 7.7 0.2567 Endpoint 2
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Table 3
Pollutant
Most
Stringent
WQO (µg/L)
No. of
Samples
No. of NonDetects
Background
Conc.
(µg/L)
Cs1
Max Effluent
Conc.
(µg/L)
Ce
Calculated
Max
Conc.
(µg/L)2
X-obs
RPA Results,
Comment3
Chloroform 130 5 0 0 2.44 0.0813 Endpoint 2
DDT 0.00017 12 10 0 0.21 0.007 Endpoint 1
Dieldrin 0.00004 12 12 0 <0.0048 <0.0002 Endpoint 3
4 Heptachlor 0.00005 12 11 0 0.14 0.0047 Endpoint 1
TCDD
equivalents 3.9E-09 5 0 0 9.34E-08 3.10E-09 Endpoint 2
Table Notes:

1. Background (Cs) is zero (0) for all pollutants except those with background concentrations specified in Table 5 of the Ocean Plan.

2. Represents the maximum concentration after complete mixing, calculated according to Step 4 of Appendix VI of the Ocean Plan using the permitted dilution ratio (Dm) of 35 as follows: X-obs = (Ce + Dm * Cs)/(Dm + 1), unless otherwise noted. The calculated maximum concentration is compared to the most stringent water quality objective to determine if effluent limitations are required. Effluent limitations are then calculated as described in Fact Sheet section 4.3.4, below.

3. RPA Results:

Endpoint 1 = An effluent limitation must be developed for the pollutant. Monitoring is required.

Endpoint 2 = An effluent limitation is not required for the pollutant. Monitoring may be required as appropriate.

Endpoint 3 = RPA is inconclusive. Less than 3 detects or greater than 80% ND.

4. The Effluent Limitation for dieldrin shall be retained from Order No. R1-2017-0002, as suggested for an Endpoint 3 result, per the Ocean Plan.

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4.3.3.3. Non-Table 3 Water Quality Objectives

4.3.3.3.1. Bacteria (Fecal Coliform Bacteria, Enterococci, and Total Coliform Bacteria)
The Ocean Plan was amended in 2019 to revise the bacterial objectives for ocean waters used for water contact recreation and shellfish harvesting.

Receiving water limitations based on the revised objectives in the Ocean Plan have been established in this Order, as further discussed in sections

4.3.3.3.2.1 and 4.3.3.2.2, below. Receiving water monitoring data between April 2017 and January 2023 demonstrates that water quality objectives for bacteria are regularly exceeded, thus effluent limitations for bacteria are necessary to protect the water contact recreation and shellfish harvesting beneficial uses of the receiving water.

4.3.3.3.1.1. Water Contact Standards (Fecal Coliform and Enterococci) The Ocean Plan includes bacterial standards for fecal coliform bacteria and enterococci for protection of ocean waters used for water contact recreation. The enterococci objectives are based on an estimated illness rate of 32 per 1,000 primary contact recreators in U.S. EPA’s 2012 Recreational Water Quality Criteria. The fecal coliform objectives were retained in the Ocean Plan, in addition to the enterococci objectives, based on California-specific epidemiological studies that suggest fecal coliform may be a better indicator of gastrointestinal illness than enterococci during certain types of exposure and environmental conditions. As a result, both objectives for enterococci and fecal coliform are applicable.

The water contact standards must be met within a zone bounded by the shoreline and a distance of 1,000 feet from the shoreline or the 30-foot depth contour, whichever is further from the shoreline. The Facility’s outfall structure consists of a 24-inch ductile iron pipe and discharges into a rocky slot in the surf zone adjacent to Battery Point Lighthouse and public access to offshore areas surrounding the Facility’s outfall is open and unrestricted. Therefore, the water contact standards are applicable to the receiving water in the vicinity of the outfall.

Although the Facility provides disinfection, inadequate or incomplete disinfection of municipal wastewater creates the potential for pathogens to be discharged. Therefore, the Regional Water Board finds the discharge has reasonable potential for pathogens and WQBELs are required.

New effluent limitations for fecal coliform and enterococci bacteria at Discharge Point 001, described below, are included in this Order.

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Because receiving water bacterial monitoring has demonstrated regular exceedances of water quality objectives for bacteria, the Permittee is required to meet the most stringent water quality standards for water contact recreation at the end of the discharge outfall:

4.3.3.3.1.1.1. Enterococci

4.3.3.3.1.1.1.1. The 6-week rolling geometric mean of enterococci shall not exceed 30 colony forming units (CFU) per 100 mL; and

4.3.3.3.1.1.1.2. No sample shall exceed a CFU of 110 per 100 mL.

4.3.3.3.1.1.2. Fecal Coliform

4.3.3.3.1.1.2.1. The 30-day geometric mean of fecal coliform density not to exceed 200 per 100 mL;

4.3.3.3.1.1.2.2. No single sample shall exceed an MPN of 400 per 100 mL.

4.3.3.3.1.2. Shellfish Standards (Total Coliform Bacteria) The Ocean Plan includes bacterial standards for total coliform bacteria for protection of ocean waters used for water contact recreation. Shellfish harvesting standards for total coliform bacteria must be maintained throughout the water column. The median concentration of total coliform bacteria shall not exceed an MPN of 70 organisms per 100 mL in a calendar month; and not more than 10 percent of samples shall exceed an MPN of 230 organisms per 100 mL.

Regional Water Board staff has determined that there is a reasonable potential that the discharge can cause or contribute to exceedances of bacterial water quality objectives for shellfish harvesting. This determination is based on the following factors:

4.3.3.3.1.2.1. The Ocean Plan specifies that shellfish standards shall be maintained through the water column (i.e., without dilution credit).

4.3.3.3.1.2.2. Total coliform bacteria have been shown to be present in the receiving water. For the period from April 2017 through January 2023, the maximum reported receiving water concentration of total coliform was 2,400 MPN/100 mL at Monitoring Location RSW-001.

4.3.3.3.1.2.3. Effluent water monitoring data for total coliform are not available to evaluate cause and culpability of receiving water quality objective exceedances, and

4.3.3.3.1.2.4. Public access to offshore areas surrounding the Facility’s outfall is open and unrestricted. Members of the public wishing to harvest shellfish in CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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the area can approach by boat and collect shellfish in accordance with state regulations.

4.3.3.3.1.3. New effluent limitations for total coliform bacteria at Discharge Point 001, described below, are included in this Order. Because receiving water bacterial monitoring has demonstrated regular exceedances of water quality objectives for bacteria, the Permittee is required to meet the applicable water quality standards for shellfish harvesting at the end of the discharge outfall.

4.3.3.3.1.3.1. Total Coliform

4.3.3.3.1.3.1.1. The median concentration shall not exceed an MPN of 70 organisms per 100 mL in a calendar month.

4.3.3.3.1.3.1.2. Not more that 10 percent of the samples shall exceed an MPN of 230/100 mL. Although the Ocean Plan specifies compliance with this objective using the results of 10 consecutive samples, this Order applies the limitation as a single sample limitation for ease of determining compliance with the limitation.

4.3.4. WQBEL Calculations
Based on results of the RPA, performed in accordance with methods of the Ocean Plan for discharges to the Pacific Ocean, the Regional Water Board is establishing WQBELs for ammonia, copper, silver, chlorine residual, endosulfan, endrin, DDT, dieldrin, heptachlor, and TCDD equivalents, at Discharge Point No. 001.

As described by Section III.C of the Ocean Plan, effluent limits for Table 3 pollutants are calculated according to the following equation.

Ce = Co + Dm (Co – Cs)
Where …
Ce = the effluent limitation (μg/L)
Co = the concentration (the water quality objective) to be met at the completion of initial dilution (μg/L)
Cs = background seawater concentration (μg/L)
Dm = minimum probable initial dilution expressed as parts seawater per part wastewater (here, Dm = 29)
For the Facility, the Dm of 29 is retained from Order No. R1-2017-0002. Initial dilution is the process that results in the rapid and irreversible turbulent mixing of CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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wastewater with ocean water around the point of discharge. In accordance with Table 3 implementing procedures, Cs equals zero for all parameters, except the following:

Table F-6. Background Seawater Concentrations – Ocean Plan Pollutant Background Seawater Concentration (μg/L)
Arsenic 3
Copper 2
Mercury 0.0005
Silver 0.016
Zinc 8
Applicable water quality objectives from Table 3 of the Ocean Plan are as follows.

Table F-7. Water Quality Objectives – Ocean Plan
Pollutant Units 6-Month
Median
Daily
Maximum
Instantaneous
Maximum
30-Day
Average
Ammonia (μg/L) 600 2400 6000 --
Copper (μg/L) 3 12 30 --
Silver (μg/L) 0.7 2.8 7 --
Total Residual
Chlorine
(μg/L) 2 8 60 --
Endosulfan (μg/L) 0.009 0.018 0.027 --
Endrin (μg/L) 0.002 0.002 0.006 --
DDT (μg/L) -- -- -- 0.00017
Dieldrin (μg/L) -- -- -- 0.00004
Heptachlor (μg/L) -- -- -- 0.00005
TCDD Equivalents (μg/L) -- -- -- 3.9 x 10-7
Using the equation, Ce = Co + Dm (Co – Cs), effluent limitations are calculated as follows. Here, Dm is equal to 29 for each effluent limitation calculation. The effluent limitations established in this Order have been rounded to two significant figures.

Ammonia
Ce = (600 + 29 (600-0))/1000 = 18 mg/L (6-Month Median) CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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Ce = (2400 + 29 (2400-0))/1000 = 72 mg/L (Daily Maximum) Ce = (6000 + 29 (6000-0))/1000 = 180 mg/L (Instantaneous Maximum) Copper
Ce = 3 + 29 (3 – 2) = 32 μg/L (6-Month Median)
Ce = 12 + 29 (12 – 2) = 300 μg/L (Daily Maximum)
Ce = 30 + 29 (30 – 2) = 840 μg/L (Instantaneous Maximum) Silver
Ce = 0.7 + 29 (0.7 – 0) = 16 μg/L (6-Month Median)
Ce = 2.8 + 29 (2.8 – 0) = 79 μg/L (Daily Maximum)
Ce = 7 + 29 (7 – 0) = 200 μg/L (Instantaneous Maximum)
Total Residual Chlorine
Ce = 2 + 29 (2 – 0) = 60 μg/L (6-Month Median)
Ce = 8 + 29 (8 – 0) = 240 μg/L (Daily Maximum)
Ce = 60 + 29 (60 – 0) = 1,800 μg/L (Instantaneous Maximum) Endosulfan
Ce = 0.009* + 29 (0.009 – 0) = 0.27 μg/L (6-Month Median) Ce = 0.018 + 29 (0.018 – 0) = 0.54 μg/L (Daily Maximum) Ce = 0.027 + 29 (0.027 – 0) = 0.81 μg/L (Instantaneous Maximum) Endrin
Ce = 0.002 + 29 (0.002 – 0) = 0.06 μg/L (6-Month Median) Ce = 0.004 + 29 (0.004 – 0) = 0.12 μg/L (Daily Maximum) Ce = 0.006 + 29 (0.006 – 0) = 0.18 μg/L (Instantaneous Maximum) DDT
Ce = 0.00017 + 29 (0.00017 – 0) = 0.0051 μg/L (30-day Average) Dieldrin
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Ce = 0.00004 + 29 (0.00004 – 0) = 0.0012 μg/L (30-day Average) Heptachlor
Ce = 0.00005 + 29 (0.00005 – 0) = 0.0015 μg/L (30-day Average) This Order does not include mass-based effluent for the WQBELs because the applicable standards for Table 3 pollutants of the Ocean Plan are expressed in terms of concentration.

4.3.5. Whole Effluent Toxicity (WET)
Monitoring triggers for chronic toxicity protect the receiving water from the aggregate effect of a mixture of pollutants that may be present in effluent. There are two types of WET tests – acute and chronic. An acute toxicity test is conducted over a short time period and measures mortality. A chronic test is conducted over a longer period of time and may measure mortality, reproduction, and/or growth.

WET requirements are derived from the CWA and the Basin Plan. The Basin Plan establishes a narrative water quality objective for toxicity that states “All waters shall be maintained free of toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in human, plant, or aquatic life.” Detrimental responses may include, but are not limited to, decreased growth rate, decreased reproductive success of resident or indicator species, and/or significant alterations in population, community ecology, or receiving water biota. For compliance with the Basin Plan’s narrative toxicity objective, this Order requires the Permittee to conduct WET testing for chronic toxicity, as specified in the MRP (Attachment E, section 5).

The Permittee conducted chronic toxicity testing using Macrocystis pyrifera, Mytilus spp. and Atherinops affinis. The following table summarizes the chronic toxicity testing results collected between August 2017 and September 2022.

Table F-8. Summary of Chronic Toxicity Results (TUc)
Date
Macrocystis pyrifera Mytilus spp Atherinops affinis
Germination
(TUc)
Growth
(TUc)
Larval
Development
(TUc)
Survival
(TUc)
Growth
(TUc)
08/03/2017 Pass
-0.27%
Pass

0.98%
Pass
-0.08%
Pass

0.00%
Pass

8.29 %
08/21/2018 -- -- --
Pass
-9.52%
Pass
-35.92%
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Date
Macrocystis pyrifera Mytilus spp Atherinops affinis
Germination
(TUc)
Growth
(TUc)
Larval
Development
(TUc)
Survival
(TUc)
Growth
(TUc)
08/20/2019 -- -- --
Pass

0.00%
Pass

12.43%
08/18/2020 -- -- --
Pass

0.00%
Pass

1.50 %
08/17/2021 -- -- --
Pass

0.00%
Pass
-11.72%
09/13/2022 -- -- --
Pass
-9.13%
Pass
-3.00%
The Ocean Plan contains toxicity testing requirements based on minimum initial dilution (Dm) factors in section III.C.4.c. Following the implementation procedures of the Ocean Plan, dischargers with Dm factors that fall below 100:1 are required to conduct chronic toxicity testing. This Order allows for a Dm of 29 for the chronic condition. The RPA conducted for the Facility does not demonstrate reasonable potential (Endpoint 1) for discharges from the Facility to cause or contribute to exceedances of applicable water quality criteria for chronic toxicity. However, the Ocean Plan, Appendix VI, states, “The Regional Water Board may use an alternative approach for assessing reasonable potential such as an appropriate stochastic dilution model that incorporates both ambient and effluent variability. The permit fact sheet or statement of basis will document the justification or basis for the conclusions of the reasonable potential assessment.” As discussed further below, the discharge does not exhibit reasonable potential to cause or contribute to an exceedance of the water quality objective for chronic toxicity based on the Test of Significant Toxicity (TST) approach in National Pollutant Discharge Elimination System Test of Significant Toxicity Implementation Document (EPA 833-R-10-003, 2010). Therefore, this Order does not contain WET limitations. However, in accordance with the Ocean Plan (section III.C, Implementation Provisions for Table 3), this Order retains chronic toxicity monitoring requirements for the discharge at Discharge Point 001.

4.3.5.1. Test of Significant Toxicity
The Ocean Plan establishes a daily maximum chronic toxicity objective of 1.0 TUc = 100/NOEC, using a five-concentration hypothesis test, and a daily maximum acute toxicity objective of 0.3 TUa = 100/LC50, using a point estimate model. In 2010, U.S. EPA endorsed the peer-reviewed Test of Significant Toxicity (TST) two-concentration hypothesis testing approach in National Pollutant Discharge Elimination System Test of Significant Toxicity Implementation Document (EPA 833-R-10-003, 2010) as an improved CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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hypothesis-testing tool to evaluate data from U.S. EPA’s toxicity test methods.

The TST hypothesis testing approach more reliably identifies toxicity—in relation to the chronic (0.25 or more) and acute (0.20 or more) mean responses of regulatory management concern—than the current NOEC hypothesis-testing approach used in the Ocean Plan.

This Order does not include effluent limitations for toxicity based on the TST approach. However, this Order does require the Permittee to monitor and report results in a manner that will allow the Regional Water Board to conduct an RPA in accordance with the TST approach at the time of the next permit renewal.

On December 1, 2020, the State Water Board adopted the Toxicity Provisions, which standardizes the regulation of aquatic toxicity for all nonoceanic surface waters. U.S. EPA’s TST approach is an essential component of this adopted toxicity amendment as it forms the basis for utilizing numeric water quality objectives and acts as the primary means of determining compliance with the proposed effluent limitations. U.S. EPA provided its final approval of the Toxicity Provisions on May 1, 2023.

In a letter dated February 12, 2014, the State Water Board submitted an alternative test process (ATP) request to U.S. EPA Region 9 for the statewide use of a two-concentration toxicity test design when using the TST approach.

This two-concentration test design is composed of a single effluent concentration and a control concentration. U.S. EPA approved the ATP request on March 17th, 2014. In June 2014, the approval was challenged in court on procedural grounds under the Administrative Procedures Act by the Southern California Alliance of Publicly Owned Treatment Works (SCAP) and the Central Valley Clean Water Association (CVCWA). The U.S. EPA withdrew the approval and notified State Water Board in a memo dated February 11, 2015. In a letter dated November 25, 2020, the State Water Board submitted a new ATP request to U.S. EPA Region 9. At the time this permit is being developed, the State Water Board is awaiting a response from U.S. EPA. The permit may be modified, if necessary, to incorporate new statewide toxicity criteria established by the toxicity amendment.

It is important to note that U.S. EPA’s rescission of its approval of the ATP is not based on the substantive TST statistical analysis or the scientific validity of a two-concentration test design. The withdrawal letter also states that currently there is a proposed rulemaking to change the language in the ATP regulations at 40 C.F.R. part 136.

The benefits of requiring the TST in new or amended permits include improving the statistical power of the toxicity test, and simplifying the analysis as compared to the traditional hypothesis statistical approaches or point estimates. The calculations are straightforward and provide a clear pass/fail CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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result. With the withdrawal of the two-concentration test design approval, an NPDES permit can still require the TST for statistical analyses.

If the two-concentration test design is approved at a future date, the MRP may be modified to remove the need for a five-concentration test. Toxicity tests shall be run using a multi-concentration test design in accordance with 40 C.F.R. section 136.3, and the TST shall be utilized with the biological responses from the permitted in-stream waste concentration (IWC) and the control (effluent concentration of zero). However, even with only two of the five concentration biological responses being used, cost savings in the form of time and effort are still realized for the statistical analysis and data interpretation carried out by the Permittee, lab, and permit manager. This Order requires application of the TST for statistical analysis of whole effluent toxicity data.

Test of Significant Toxicity Design
The TST’s null hypothesis for chronic toxicity is:

H0: Mean response (In-stream Waste Concentration (IWC) in % effluent) ≤

0.75 mean response (control)
Results are analyzed using the TST approach and an acceptable level of chronic toxicity is demonstrated by rejecting the null hypothesis and reporting “Pass” or “P”.

The chronic IWC (in % effluent) for Discharge Point 001 is 3.45%1. The chronic toxicity trigger for Discharge Point 001 is expressed as a null hypothesis (H0) and regulatory management decision (b value) of 0.75 for the chronic toxicity methods in the MRP. The null hypothesis for this discharge is:

H0: Mean response (3.45% effluent) ≤ 0.75 mean response (control) The Permittee conducted chronic toxicity testing at the IWC of 3.45% during the term of Order No. R1-2017-0002. As shown in Table F-8, all chronic toxicity tests collected between August 2017 and September 2022 resulted in “Pass” at the IWC of 3.45%, indicating that the discharge does not exhibit reasonable potential to cause or contribute to an exceedance of water quality objectives for chronic toxicity using the TST approach. Therefore, this Order does not include an effluent limitation for chronic toxicity.

This Order requires annual monitoring for chronic toxicity at Monitoring Location EFF-001. Results shall be analyzed using the TST hypothesis testing approach in section 5.1.6.1 of the MRP. Compliance with this chronic toxicity limitation is demonstrated by rejecting the null hypothesis and reporting “Pass” or “P”.

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When the chronic toxicity test results in a “Fail” or “F,” the Permittee must initiate accelerated monitoring as specified in the MRP (Attachment E, section 5). After accelerated monitoring, if conditions of chronic toxicity are found to persist, the Permittee will be required to conduct a TRE, as described in section 5.2 of the MRP.

Notification requirements for chronic WET testing include a 72-hour verbal notification requirement and a 14-day written report requirement, if test results indicate toxicity. The 14-day written notification is established in the U.S. EPA WET Guidance documents cited in the MRP. The 72-hour verbal notification requirement is being added to provide the Regional Water Board with knowledge of the toxicity in advance of the written report. The 72-hour requirement is intended to give the Permittee sufficient time to make a telephone call to Regional Water Board staff and accounts for non-working days (e.g., weekends). Verbal notification of WET test exceedances may be left by voice mail if the Regional Water Board staff person is not immediately available by telephone.

This Order retains the requirement for the Permittee to conduct a screening test using at least one vertebrate, invertebrate, and plant species. After the screening test is completed, monitoring can be reduced to the most sensitive species.

Chronic WET limitations will be established if future monitoring results demonstrate that discharges from the Facility are causing or contributing to chronic toxicity in the receiving water.

4.4. Final Effluent Limitation Considerations

4.4.1. Anti-Backsliding Requirements
Sections 402(o) and 303(d)(4) of the CWA and federal regulations at 40 C.F.R. section 122.44(l) prohibit backsliding in NPDES permits. These anti-backsliding provisions require effluent limitations in a reissued permit to be as stringent as those in the previous permit, with some exceptions where limitations may be relaxed. The effluent limitations in this Order are at least as stringent as the effluent limitations in the previous Order, with the exception of mass-based effluent limitations for BOD5 and TSS, and effluent limitations for nickel and TCDD equivalents, as explained below.

Order No. R1-2017-0002 established final mass-based effluent limitations for BOD5 and TSS. Historically, the Regional Water Board routinely incorporated mass-based limits (in addition to concentration-based limits) for BOD5 and TSS in NPDES permits to encourage correction of I&I. Applied in this way, massbased limitations effectively restrict a POTW’s wet weather influent flows to less than or equal to the Facility’s design capacity in situations where POTWs experience excessive I&I as a result of climate conditions and/or aging CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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infrastructure. The application of mass-based effluent limitations for BOD5 and TSS is not necessary to limit wet weather inflow to the Facility because the Order includes flow limitations (Discharge Prohibition 3.7) that require the Permittee to control influent flow to stay below the design capacity of the Facility.

Mass limitations for BOD5 and TSS for discharges of treated wastewater have been removed because Regional Water Board staff misinterpreted the exception of 40 C.F.R. section 122.45(f)(2), which states that mass limitations are not required “when applicable standards and limitations are expressed in terms of other units of measure.” Secondary treatment standards for BOD5 and TSS in 40 C.F.R. section 133.102, on which the effluent limitations in previous permits were based, are expressed in terms of concentration and percent removal (i.e., other units of measure). The relaxation of effluent limitations for BOD5 and TSS in this Order is permissible under 40 C.F.R. sections 122.44(l)(1) and 122.62(a)(15), because Regional Water Board staff has determined that massbased limitations for BOD5 and TSS were applied in the previous permits as a result of a mistaken interpretation of law when issuing those previous permits.

In addition, Regional Water Board staff previously held that anti-backsliding regulations prevented the removal of mass-based limitations for BOD5 and TSS because they were appropriate and necessary to protect water quality and prevent water quality degradation in receiving waters. While it is conceivable that the absence of mass-based limitations for these pollutants may result in an increased pollutant loading to surface waters, recent self-monitoring reports indicate that compliance with concentration-based effluent limitations for BOD5 and TSS effectively maintain the Permittee’s mass emission rates for BOD5 and TSS well below permitted mass-based limitations. In addition, even if there is a resulting increase in pollutant loading, there is no evidence that the increase will result in degradation of water quality. Therefore, relaxation of effluent limitations for BOD5 and TSS in this Order is also permissible under 40 C.F.R. sections 122.44(l)(1) and 122.62(a)(15), based on new information available to the Regional Water Board.

Order No. R1-2017-0002 established final effluent limitations for nickel and TCDD equivalents. As shown in Table F-5 of this Fact Sheet, effluent data demonstrate that the discharge no longer demonstrates reasonable potential to cause or contribute to an exceedance of the water quality objective for nickel and TCDD equivalents. The updated effluent data for nickel and TCDD equivalents constitutes new information, which permits the removal of effluent limitations consistent with CWA section 402(o)(2)(B). Additionally, for attainment waters, CWA section 303(d)(4)(B) specifies that a limitation based on a water quality standard may be relaxed where the action is consistent with the antidegradation policy. The Pacific Ocean is considered an attainment water for nickel and TCDD because the receiving water is not listed as impaired on the 303(d) list for these constituents. As discussed in Fact Sheet section 4.4.2 below, removal of the effluent limits complies with federal and state CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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antidegradation requirements. Thus, removal of these effluent limitations meets the exception in CWA section 303(d)(4)(B).

Order No. R1-2017-0002 also retained final effluent limitations for fecal coliform for the protection of shellfish harvesting. The National Shellfish Sanitation Program (NSSP) is the federal/state cooperative program recognized by the U.

S. Food and Drug Administration (FDA) and the Interstate Shellfish Sanitation Conference (ISSC) for the sanitary control of shellfish produced and sold for human consumption. The NSSP Guide for the Control of Molluscan Shellfish allows for the use of either fecal coliform or total coliform in protecting shellfish harvesting areas. Additionally, the Ocean Plan contains total coliform water quality objectives for the protection of shellfish harvesting. These total coliform water quality objectives have been established as effluent limitations in this Order in place of the historical fecal coliform effluent limitations. The Pacific Ocean, in the vicinity of the discharge, is not listed as an impaired waterbody on the 303(d) list. As discussed in Fact Sheet section 4.4.2 below, relaxation of this limit complies with federal and state antidegradation requirements. Thus, relaxation of this effluent limitation meets the exception in CWA section 303(d)(4)(B).

4.4.2. Antidegradation Policies
State Water Board Resolution 68-16, the Statement of Policy with Respect to Maintaining High Quality Waters in California (the Antidegradation Policy) requires that disposal of waste into waters of the state be regulated to achieve the highest water quality consistent with the maximum benefit to the people of the state. The quality of some waters is higher than established by adopted policies and that higher quality water shall be maintained to the maximum extent possible consistent with the Antidegradation Policy. The Antidegradation Policy requires that (1) higher quality water will be maintained until it has been demonstrated to the state that any change will be consistent with the maximum benefit to the people of the state, will not unreasonably affect present and anticipated beneficial use of the water, and will not result in water quality less than that prescribed in the policies; and (2) any activity that produces a waste or may produce waste or increased volume or concentration of waste and discharges to existing high quality water will be required to meet waste discharge requirements that will result in the best practicable treatment or control (BPTC) of the discharge necessary to assure pollution or nuisance will not occur, and the highest water quality consistent with the maximum benefit to the people of the state will be maintained.

Discharges from the Facility are required to maintain protection of the beneficial uses of the receiving water and comply with applicable provisions of the Basin Plan.

This Order is consistent with applicable federal and state antidegradation policies, as it does not authorize the discharge of increased concentrations of CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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pollutants or increased volumes of treated wastewater beyond that which was permitted to discharge in accordance with Order No. R1-2017-0002.

4.4.3. Stringency of Requirements for Individual Pollutants This Order contains both technology-based and water quality-based effluent limitations for individual pollutants. The technology-based effluent limitations consist of restrictions on BOD5, oil and grease, pH, settleable solids, TSS, and turbidity. Restrictions on these pollutants are discussed in section 4.2 of this Fact Sheet. This Order’s technology-based pollutant restrictions implement the minimum, applicable federal technology-based requirements.

In addition, this Order contains effluent limitations for chlorine residual that are more stringent than the minimum, federal technology-based requirements but are necessary to meet water quality standards. These requirements are discussed in section 4.3.3.3.1 of the Fact Sheet.

Water quality-based effluent limitations have been derived to implement water quality objectives that protect beneficial uses. Both the beneficial uses and the water quality objectives have been approved pursuant to federal law and are the applicable federal water quality standards. The procedures for calculating the individual water quality-based effluent limitations are based on the Ocean Plan, which was approved by U.S. EPA on February 14, 2006 and has since been further amended. Most beneficial uses and water quality objectives contained in the Basin Plan were approved under state law and submitted to and approved by U.S. EPA prior to May 30, 2000. Any water quality objectives and beneficial uses submitted to U.S. EPA prior to May 30, 2000, but not approved by U.S.

EPA before that date, are nonetheless “applicable water quality standards for purposes of the CWA” pursuant to 40 C.F.R. section 131.21(c)(1). The remaining water quality objectives and beneficial uses implemented by this Order were approved by U.S. EPA and are applicable water quality standards pursuant to section 131.21(c)(2). Collectively, this Order’s restrictions on individual pollutants are no more stringent than required to implement the requirements of the CWA.

The Regional Water Board has considered the factors in Water Code section 13263, including the provisions of Water Code 13241, in establishing these requirements.

4.5. Interim Effluent Limitations – Not Applicable
This Order does not establish interim effluent limitations or schedules for compliance with final limitations.

4.6. Land Discharge Specifications – Not Applicable
This Order does not authorize discharges of waste to land.

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4.7. Recycling Specifications
This Order includes recycled water production requirements in section 4.3.1 of the Order and Water Recycling Specifications and Requirements contained in section

4.3.2. of the Order. The Permittee currently has no recycled water use sites. Prior to initiating recycled water use at recycled water use sites identified in the future, the Permittee must obtain permitting, either through a modification of this Order or by enrolling under State Water Board Order DWQ 2016-0068-DDW (or any subsequent revision) and submit a title 22 Recycled Water Engineering Report that has been approved by DDW.

4.7.1. Scope and Authority
Section 13263 of the Water Code requires the Regional Water Board to prescribe requirements for proposed discharges, existing discharges, or material change in an existing discharge based upon the conditions of the disposal area or receiving waters upon or into which the discharge is made or proposed. The prescribed requirements shall implement any relevant water quality control plans that have been adopted, and shall take into consideration the beneficial uses to be protected, the water quality objectives reasonably required for that purpose, other waste discharges, the need to prevent nuisance, and the provisions of Water Code section 13241. In prescribing requirements, the Regional Water Board is not obligated to authorize the full waste assimilation capacities of the receiving water.

Water Code section 13241 requires the Regional Water Board to establish water quality objectives in water quality control plans as in its judgment will ensure the reasonable protection of beneficial uses and prevention of nuisance, recognizing that it may be possible for the quality of water to be changed to some degree without unreasonably affecting beneficial uses. The Basin Plan establishes water quality objectives specific to the North Coast Region for the protection of past, present, and probable future beneficial uses of water. Factors required for consideration during development of applicable water quality objectives, such as the characteristics of the hydrographic unit under consideration, economic considerations, and other factors required in accordance with section 13241 were considered during the Basin Planning and adoption process.

Here, the Regional Water Board considered all of these factors when developing waste discharge requirements for the recycled water discharge. Limitations for BOD5, TSS, total coliform, and pH were derived based upon the treatment capability of the Facility in order to implement water quality objectives that protect the beneficial uses of both surface and groundwater. Both beneficial uses and the water quality objectives have been approved pursuant to state law, and then submitted to and approved by U.S. EPA. In addition, discharge prohibitions were included to prohibit the reclamation use of untreated or partially treated wastewater.

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The Regional Water Board considered the factors set forth in Water Code section 13241, including the consideration of past, present, and probable future beneficial uses of the receiving water, which the Regional Water Board anticipates to be the same as set forth in the Basin Plan. The Regional Water Board considered the environmental characteristics, including water quality of the Smith River Hydrologic Unit, the coordinated control of all factors, which affect water quality in the area, and the need to develop and use recycled water, which this Order supports. The Permittee did not submit any evidence regarding whether the waste discharge requirements for recycled water discharges would interfere with the development of needed housing within the region or the costs of compliance, particularly anything to show that the costs of compliance with the Order would be unmanageable.

4.7.2. Applicable Beneficial Uses and Water Quality Criteria and Objectives

4.7.2.1. Beneficial Uses. Beneficial use designations for groundwater established in the Basin Plan include MUN, AGR, IND, and PRO.

4.7.2.2. Basin Plan Water Quality Objectives. The Basin Plan contains narrative objectives for tastes and odors, bacteria, radioactivity, and chemical constituents (including those chemicals that adversely affect agricultural water supply) that apply to groundwater.

4.7.3. Determining the Need for Requirements for Water Recycling Section 4.3. of this Order contains Water Recycling Specifications and Requirements to ensure that recycled water is used in a manner that is protective of groundwater and surface water quality. The Water Recycling Specifications and Requirements are established in this Order to conform to requirements contained in title 22, division 4, chapter 3 of the CCR for recycled water use of disinfected tertiary-2.2 recycled water. The Permittee is required to comply with applicable state and local requirements regarding the production and use of recycled wastewater, including requirements of Water Code sections 13500 – 13577 (Water Reclamation) and DDW regulations at title 22, sections 60301 – 60357 of the CCR (Water Recycling Criteria).

The Water Recycling Specifications and Requirements are established in this Order to conform to requirements contained in title 22, division 4, chapter 3 of the CCR for the recycled water use of disinfected tertiary effluent. Specific water recycling requirements are enumerated in section 4.3 of this Order. The requirement to comply with title 22 requirements is retained from Order No. R1- 2017-0002.

4.7.3.1. BOD5 and TSS. This Order retains discharge limitations for BOD5 and TSS from Order No. R1-2017-0002 and are based on technology-based effluent limitations that consist of a monthly average of 10 mg/L and a weekly average of 15 mg/L. These levels are technically achievable based on the capability of CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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the wastewater treatment system. These limits are included in the Order to ensure that discharges to the recycled water system receive proper treatment.

4.7.3.2. Coliform Bacteria. Consistent with Order No. R1-2017-0002, this Order includes recycling specifications for coliform bacteria that reflect standards for tertiary treated recycled water adopted by the DDW in title 22 of the CCR and are included to ensure that recycled water quality is protective of human health. Recycled water from this Facility meets the highest title 22 treatment and disinfection standards and is suitable for the broad range of recycled water uses identified in title 22, including urban land uses.

4.7.3.3. pH. This Order retains instantaneous minimum and maximum effluent limitations for pH of 6.0 and 9.0, respectively, from Order No. R1-2017-0002 and are based on the technology-based effluent limitations required by U.S.

EPA pursuant to 40 C.F.R. part 133. These pH limitations are included in the Order to ensure that pH levels are appropriate for protection of groundwater when discharging to the recycled water system.

4.7.4. Satisfaction of Antidegradation Policy
The permitted discharge is consistent with the antidegradation provisions of State Water Board Resolution No. 68-16. This Order does not provide for an increase in the volume and mass of pollutants discharged. The discharge will not have significant impacts on the beneficial uses of groundwater because the Order does not authorize the discharge of treated wastewater to groundwater.

4.8. Other Requirements
The Order contains additional specifications that apply to the Facility when discharging to the recycled water system, including:

4.8.1. Filtration System Requirements. The turbidity requirement in section 4.3.3.2 of the Order and section 9.3 of the MRP are in accordance with the definition of filtered wastewater found in title 22 section 60301.320 of the CCR. The title 22 definition is used as a reasonable performance standard to ensure adequate removal of turbidity upstream of disinfection facilities. Properly designed and operated effluent filters will meet this standard. The point of compliance for the turbidity requirements is a point following filtration and before discharge to the UV disinfection system.

4.8.2. Disinfection Process Requirements for the Chlorine Disinfection System.

Internal monitoring at the end of the chlorine contact tank is required to measure chlorine residual in lieu of daily coliform monitoring to assure adequate disinfection on a daily basis. Section 4.4.1 of the Order and section 9.4 of the MRP require the Permittee monitor and report chlorine residual on a continuous basis at Monitoring Location INT-002A as a means to demonstrate that an appropriate chlorine residual concentration is maintained in the effluent at Monitoring Location INT-002A at all times.

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4.8.3. Disinfection Process Requirements for the UV Disinfection System. The Order contains monitoring requirements for the UV disinfection system in section 4.3.4 of the Order and section 9.5 of the MRP. These requirements are needed to determine compliance with requirements for recycled wastewater systems, established at CCR title 22, division 4, chapter 3 and to ensure that the disinfection process achieves effective pathogen reduction. Prior to initiation of any water recycling, the Permittee must complete an evaluation of the UV disinfection system to demonstrate that it meets the requirement in title 22, section 60301.230(a)(2) that the disinfection process, when combined with the filtration process, inactivates and/or removes 99.999 percent of the plaqueforming units of F-specific bacteriophage MS2, or polio virus in the wastewater.

UV system operation requirements are necessary to ensure that adequate UV dosage is applied to the wastewater to inactivate pathogens (e.g., viruses, bacteria) in the wastewater. UV dosage is dependent on several factors such as UV transmittance, UV power setting, and wastewater flow through the UV system. Minimum dosage requirements are based on recommendations by DDW and guidelines established by the National Water Research Institute (NWRI) and American Water Works Association Research (AWWARF) "Ultraviolet Disinfection Guidelines for Drinking Water and Water Reuse" first published in December 2000 revised as a Third Edition dated August 2012 (NWRI/AWWARF UV Disinfection Guidelines). Furthermore, a Memorandum dated November 1, 2004 issued by DDW to Regional Water Board Executive Officers recommended that provisions be included in permits for water recycling treatment plants employing UV disinfection requiring permittees to establish fixed cleaning frequency of quartz sleeves as well as include provisions that specify minimum delivered UV dose that must be maintained (as recommended by the NWRI/AWWARF UV Disinfection Guidelines). Minimum UV dosage requirements specified in section 4.3.4.3 of the Order ensures that adequate disinfection of wastewater will be achieved.

Section 4.3.4.16 of the Order restricts the flow of discharges to the recycled water system. Based upon the equations developed, at the highest flow of 830 gallons per minute (gpm), one reactor cannot provide the required UV dose if the UV transmittance (UVT) drops below 78 percent. A third UV reactor is needed to address all operational conditions, including any flow up to 830 gpm and any UVT down to 65%, while still providing adequate redundancy. The NWRI/AWWARF UV Disinfection Guidelines state, “At a minimum, two reactors must be simultaneously operated in any on-line reactor train.” It continues by requiring a redundant reactor in a single treatment train, “Standby UV equipment must be provided: A standby reactor per train. [OR] A standby reactor train.” Further the NWRI/AWWARF UV Disinfection Guidelines state the system must be capable of applying the required dose “with any failed or out-of-service reactor.” Examples include failure of the power supply, cleaning mechanism, cooling system, SCADA system, or a damaged UV intensity sensor. Until this reliability issue is sufficiently addressed, this Order restricts the flow to the CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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recycled water system to 0.6 mgd, which is one-half of the design flow of the 1.2 mgd.

5. RATIONALE FOR RECEIVING WATER LIMITATIONS

5.1. Surface Water
CWA section 303(a-c) requires states to adopt water quality standards, including criteria where they are necessary to protect beneficial uses. The State Water Board adopted water quality criteria as water quality objectives in the Ocean Plan.

Receiving water limitations within this Order reflect all applicable, general water quality objectives of the Ocean Plan.

The Ocean Plan includes numeric and narrative water quality objectives for various beneficial uses. This Order contains receiving water limitations for discharges to the Pacific Ocean based on the Ocean Plan numerical and narrative water quality objectives for bacteria, dissolved oxygen, floating particulates, oil and grease, pH, discoloration, natural lighting, deposition of solids, dissolved sulfides, organic materials in sediments, Table 3 parameters, nutrient materials, radioactive wastes, and biological characteristics.

5.2. Groundwater

5.2.1. Groundwater limitations in this Order have been retained from the previous Order with minor modification to reflect revised sections of title 22. Groundwater limitations are included in the Order to protect the beneficial uses of the underlying groundwater. The beneficial uses of the underlying groundwater are municipal and domestic supply, industrial service supply, industrial process supply, agricultural supply, and freshwater replenishment to surface waters.

Discharges from the Facility shall not cause exceedance of applicable water quality objectives or create adverse impacts to beneficial uses of groundwater.

Groundwater data must be evaluated using appropriate statistical tools to determine when groundwater degradation is occurring.

The Order includes a new groundwater toxicity limitation that was adopted by the Regional Water Board on June 18, 2015, and effective beginning July 18, 2016 after receiving approval from the California Office of Administrative Law.

This new Basin Plan limit requires that groundwaters shall not contain toxic substances in concentrations that are toxic to, or that produce detrimental physiological responses in humans, or that adversely affects beneficial uses.

This limitation applies regardless of whether the toxicity is caused by a single substance or the synergistic effect of multiple substances..

CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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ATTACHMENT F – FACT SHEET F-46

6. RATIONALE FOR PROVISIONS

6.1. Federal Standard Provisions
Standard Provisions, which apply to all NPDES permits in accordance with 40 C.F.R. section 122.41, and additional conditions applicable to specified categories of permits in accordance with 40 C.F.R. section 122.42, are provided in Attachment D to the order. The Permittee must comply with all standard provisions and with those additional conditions that are applicable under 40 C.F.R. section 122.42. The rationale for the special conditions contained in the Order is provided in section 6.2, below.

Sections 122.41(a)(1) and (b) through (n) of 40 C.F.R. establish conditions that apply to all State-issued NPDES permits. These conditions must be incorporated into the permits either expressly or by reference. If incorporated by reference, a specific citation to the regulations must be included in the Order. Section 123.25(a)(12) allows the state to omit or modify conditions to impose more stringent requirements. In accordance with 40 C.F.R. section 123.25, this Order omits federal conditions that address enforcement authority specified in 40 C.F.R. sections 122.41(j)(5) and (k)(2) because the enforcement authority under the Water Code is more stringent. In lieu of these conditions, this Order incorporates by reference Water Code section 13387(e).

6.2. Regional Water Board Standard Provisions
In addition to the Federal Standard Provisions (Attachment D), the Permittee shall comply with the Regional Water Board Standard Provisions provided in Standard Provisions 6.1.2 of the Order.

6.2.1. Order Provision 6.1.2.1 identifies the state’s enforcement authority under the Water Code, which is more stringent than the enforcement authority specified in the federal regulations (e.g., 40 C.F.R. sections 122.41(j)(5) and (k)(2)).

6.2.2. Order Provision 6.1.2.2 requires the Permittee to notify Regional Water Board staff, orally and in writing, in the event that the Permittee does not comply or will be unable to comply with any Order requirement. This provision requires the Permittee to make direct contact with a Regional Water Board staff person.

6.3. Special Provisions

6.3.1. Reopener Provisions

6.3.1.1. Standard Revisions (Special Provision 6.3.1.1). Conditions that necessitate a major modification of a permit are described in 40 C.F.R. section 122.62, which include the following:

6.3.1.1.1. When standards or regulations on which the permit was based have been changed by promulgation of amended standards or regulations or by judicial CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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decision. Therefore, if revisions of applicable water quality standards are promulgated or approved pursuant to Section 303 of the CWA or amendments thereto, the Regional Water Board will revise and modify this Order in accordance with such revised standards.

6.3.1.1.2. When new information that was not available at the time of permit issuance would have justified different permit conditions at the time of issuance.

6.3.1.2. Reasonable Potential (Special Provision 6.3.1.2). This provision allows the Regional Water Board to modify, or revoke and reissue, this Order if present or future investigations demonstrate that the Permittee governed by this Permit is causing or contributing to excursions above any applicable priority pollutant criterion or objective, or adversely impacting water quality and/or the beneficial uses of receiving waters.

6.3.1.3. Whole Effluent Toxicity (Special Provision 6.3.1.3). This Order requires the Permittee to investigate the causes of, and identify corrective actions to reduce or eliminate effluent toxicity through a TRE. This Order may be reopened to include a numeric acute and/or chronic toxicity limitation, and/or a limitation for a specific toxicant identified in the TRE.

6.3.1.4. 303(d)-Listed (Special Provision 6.3.1.4). This provision allows the Regional Water Board to reopen this Order to modify existing effluent limitations or add effluent limitations for pollutants that are subject of any future TMDL action.

6.3.1.5. Zone of Initial Dilution/Mixing Zone (Special Provision 6.3.1.5). This provision allows the Regional Water Board to reopen this Order to modify effluent limitations based on a revised minimum initial dilution based on the results of an effluent discharge evaluation.

6.3.2. Best Management Practices and Pollution Prevention

6.3.2.1. Pollutant Minimization Program (Special Provision 6.3.2.1). This provision is included in this Order pursuant to section III.C.9 of the Ocean Plan. The Regional Water Board includes standard provisions in all NPDES permits requiring development of a Pollutant Minimization Program when there is evidence that a toxic pollutant is present in the effluent at a concentration greater than an applicable effluent limitation.

6.3.3. Construction, Operation, and Maintenance Specifications

6.3.3.1. Operation and Maintenance (Special Provision 6.3.3.1, 6.3.3.2, and

6.3.3.3). 40 C.F.R. section 122.41(e) requires proper operation and maintenance of permitted wastewater systems and related facilities to achieve compliance with permit conditions. An up-to-date operation and maintenance manual, as required by Provision 6.3.3.2 of this Order, is an integral part of a well-operated and maintained facility.

CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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ATTACHMENT F – FACT SHEET F-48

6.3.3.2. Septage Handling Requirements (Special Provision 6.3.3.4). The Permittee was not permitted to accept or treat septage at the Facility in the previous permit, but is contemplating whether to develop a program for receiving septage into the Facility to satisfy the need for local septage disposal. Domestic septage is defined as the liquid or solid material removed from a septic tank, cesspool, portable toilet, type III marine sanitation device, recreational vehicle’s sanitation tank, or similar storage or treatment works that receives only domestic septage. Septage is characterized by high organic strength, high solids content, high odor potential, high vector attraction potential, and high potential to pollute groundwater. Septage may be 6 to 80 times more concentrated than typical municipal wastewater and may also contain heavy metals and illicitly dumped hazardous materials. Septage has the potential to upset plant treatment operations or process performance or both if the plant is not designed to handle septage. Some of the impacts of septage addition to facilities include: potential toxic shock to biological processes; increased odor emissions; increased volume of grit, scum, screenings, and sludge; increased organic loading to biological processes; and increased housekeeping requirements. Prior to accepting septage, this Order requires the Permittee to submit a Septage Management Plan for approval by the Regional Water Board Executive Officer. This Order also requires the Permittee to manage septage accepted at the Facility in a manner that ensures that pollutants associated with domestic septage do not pass through or interfere with the operation or performance of the Facility, and to monitor septage as specified in section 9.7 of the MRP.

6.3.4. Special Provisions for Publicly-Owned Treatment Works (POTWs)

6.3.4.1. Pretreatment of Industrial Waste (Special Provision 6.3.4.1) Section 402(b)(8) of the CWA requires that POTWs receiving pollutants from significant industrial sources subject to section 307(b) standards establish an industrial pretreatment program to ensure compliance with these standards.

The implementing regulations at 403.8(a) state, “any POTW (or combination of POTWs operated by the same authority) with a total design flow greater than 5 million gallons per day (mgd) and receiving from industrial users pollutants which pass through or interfere with the operation of the POTW or are otherwise subject to pretreatment standards will be required to establish a POTW pretreatment program unless the NPDES State exercises its option to assume local responsibilities as provided in 403.10(e).” The Facility receives industrial wastewater from three non-categorical significant industrial users; Rumiano Cheese Company, SeaQuake Brewery, and Port O’ Pints Brewery.

Consistent with Order No. R1-2017-0002, this Order requires the Permittee to comply with pretreatment standards as described in section 307(b) of the CWA and section 403.8(a).

6.3.4.2. Sludge Disposal and Handling Requirements (Special Provision 6.3.4.2) The disposal or reuse of wastewater treatment screenings, sludges, or other solids removed from the liquid waste stream is regulated by 40 C.F.R. parts CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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257, 258, 501, and 503, and the State Water Board promulgated provisions of title 27 of the CCR. Sludge generated at the Facility is currently disposed of in a landfill.

This provision also requires the Permittee to comply with the state’s regulations relating to the discharge of biosolids to the land. The discharge of biosolids through land application is not currently regulated under this Order.

In the event that the Permittee wishes to discharge biosolids to land, the Permittee is required to either submit a report of waste discharge or dispose of biosolids at another permitted facility.

6.3.4.3. Wastewater Collection System (Special Provision 6.3.4.3) On December 6, 2022, the State Water Board adopted State Water Board Order No. WQ 2022-0103-DWQ, Statewide Waste Discharge Requirements, General Order for Sanitary Sewer Systems. This Order becomes effective on June 5, 2023 and shall replace Order No. 2006-0003-DWQ. The General Order requires public agencies that own or operate sanitary sewer systems with sewer lines one mile of pipe or greater to enroll for coverage and comply with the General Order. The General Order requires agencies to develop sanitary sewer management plans and report all sanitary sewer overflows, among other requirements and prohibitions.

6.3.4.4. Operator Certification (Special Provision 6.3.4.4). This provision requires the Facility to be operated by supervisors and operators who are certified as required by title 23, section 3680 of the CCR.

6.3.4.5. Ensuring Adequate Capacity (Special Provision 6.3.4.5). The goal of this provision is to ensure appropriate and timely planning by the Permittee to ensure adequate capacity for the protection of public health and water quality.

6.3.5. Other Special Provisions

6.3.5.1. Storm Water (Special Provision 6.3.5.1). This provision requires the Permittee, if applicable, to obtain coverage under the State Water Board’s Water Quality Order No. 2014-0057-DWQ, NPDES General Permit No.

CAS000001, General Permit for Storm Water Discharges Associated with Industrial Activities (or subsequent renewed versions of the NPDES General Permit CAS000001). Currently, the Facility is exempted from these requirements because all storm water is captured and treated and/or disposed of within the Facility’s NPDES permitted process wastewater.

6.3.6. Compliance Schedules – Not Applicable
This Order does not establish interim effluent limitations or schedules of compliance for final numeric effluent limitations.

CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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7. RATIONALE FOR MONITORING AND REPORTING REQUIREMENTS
CWA section 308 and 40 C.F.R. sections 122.41(h), (j)-(l), 122.44(i), and 122.48 require that all NPDES permits specify monitoring and reporting requirements. Water Code sections 13267 and 13383 also authorize the Regional Water Board to establish monitoring, inspection, entry, reporting, and recordkeeping requirements.

The Monitoring and Reporting Program (MRP), Attachment E of this Order establishes monitoring, reporting, and recordkeeping requirements that implement federal and state requirements. The following provides the rationale for the monitoring and reporting requirements contained in the MRP for this facility.

7.1. Influent Monitoring

7.1.1. Influent monitoring requirements at Monitoring Location INF-001 for BOD5 and TSS are retained from Order No. R1-2017-0002 and are necessary to determine compliance with the Order’s 85 percent removal requirement for these parameters.

7.1.2. Influent monitoring requirements for flow at Monitoring Location INF-001 are retained from Order No. R1-2017-0002 and are necessary to determine compliance with Discharge Prohibition 3.7.

7.1.3. Influent monitoring requirements for priority pollutants at Monitoring Location INF-001 are retained from Order No. R1-2017-0002 and are necessary to satisfy U.S. EPA pretreatment requirements.

7.2. Effluent Monitoring

7.2.1. Effluent monitoring requirements are necessary to determine compliance with prohibitions and/or effluent limitations established by the Order. Monitoring at Monitoring Location EFF-001 is necessary to demonstrate compliance with effluent limitations and demonstrate whether or not the discharge poses reasonable potential for a pollutant to exceed any numeric or narrative water quality objectives for discharges to the Pacific Ocean.

7.2.1.1. Effluent monitoring requirements for flow, BOD5, TSS, settleable solids, oil and grease, turbidity, pH, fecal coliform, ammonia, and copper have been retained from Order No. R1-2017-0002.

7.2.1.2. Effluent monitoring and sample type for chlorine residual has been changed to continuous monitoring with a meter. Continuous monitoring to demonstrate that the discharge at Monitoring Location EFF-001 at all times meets the chlorine residual effluent limitations in section 4.1.1, Table 4 of the Order is necessary due to the toxicity of chlorine to aquatic life.

7.2.1.3. Monitoring data collected during the term of Order No. R1-2017-0002 indicates that the discharge does not exhibit reasonable potential to cause or contribute to an exceedance of the Ocean Plan water quality objectives for CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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nickel and TCDD equivalents. Therefore, this Order discontinues monthly effluent monitoring requirements for nickel and annual effluent monitoring requirements for TCDD equivalents from Order No. R1-2017-0002.

7.2.1.4. Monitoring data collected over the term of Order No. R1-2017-0002 demonstrated that the discharge exhibits reasonable potential to cause or contribute to an exceedance of water quality criteria for silver, endosulfans, endrin, DDT, and heptachlor. Therefore, this Order establishes new monitoring requirements for silver, endosulfans, endrin, DDT, and heptachlor to determine compliance with applicable effluent limitations.

7.2.1.5. Monitoring data collected during the term of Order No. R1-2017-0002 indicates that water quality objectives for bacteria are regularly exceeded in the receiving waters. Therefore, this Order establishes new effluent monitoring requirements for total coliform and enterococci to evaluate cause and culpability of the discharge to these exceedances.

7.2.1.6. Consistent with Order No. R1-2017-0002, effluent monitoring requirements for Ocean Plan Table 3 pollutants are required annually to generate adequate data to perform an RPA.

7.3. Whole Effluent Toxicity Testing Requirements
Whole effluent toxicity (WET) monitoring requirements are established for discharges to the Pacific Ocean from Discharge Point 001 at Monitoring Location EFF-001 and are included in the Order to protect the receiving water quality from the aggregate effect of a mixture of pollutants in the effluent. Acute toxicity testing measures mortality in 100 percent effluent over a short test period and chronic toxicity testing is conducted over a longer time period and may measure mortality, reproduction, and/or growth. The Ocean Plan (section III.C.4.c.(4)) requires only chronic testing where the minimum initial dilution of the effluent is below 100:1.

Because this Order allows for a Dm of 29 for the Facility, WET monitoring shall consist of chronic toxicity testing. This Order includes monitoring requirements for chronic toxicity to assess whether there is reasonable potential to exceed the Ocean Plan’s narrative water quality objectives for toxicity. Consistent with Order No. R1-2017-0002, this Order requires annual chronic toxicity testing.

In addition to routine toxicity monitoring, this Order requires the Permittee to maintain and update their TRE Work Plan, in accordance with appropriate U.S.

EPA guidance to ensure that the Permittee has a plan to immediately move forward with the initial tiers of a TRE in the event effluent toxicity is encountered in the future. The TRE is initiated by evidence of a pattern of toxicity demonstrated through the additional effluent monitoring provided as a result of an accelerated monitoring program.

7.4. Land Discharge Monitoring Requirements – Not Applicable This Order does not authorize discharges to land.

CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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ATTACHMENT F – FACT SHEET F-52

7.5. Recycling Monitoring Requirements
This Order requires that the Permittee comply with applicable state and local requirements regarding the production of recycled wastewater. Recycled water requirements will apply if and when the Permittee establishes a recycled water system. Recycled water monitoring requirements for flow, BOD5, TSS, pH, total coliform bacteria, nitrate, nitrite, ammonia, organic nitrogen, and total dissolved solids have been retained from Order No. R1-2017-0002.

Section 13523.1(b)(4) of the Water Code requires quarterly recycled water reporting.

7.5.1. When discharging recycled water to the recycled water system, the Permittee must monitor its treated effluent for BOD5, TSS, pH, and total coliform bacteria to demonstrate compliance with water recycling specifications in section 4.3.1 of the Order. If the Permittee is discharging concurrently to the ocean and to the recycled water system, the same sample may satisfy monitoring and reporting requirements for both discharge points.

7.5.2. Recycled water monitoring requirements for nitrate, nitrite, ammonia and organic nitrogen are included to determine the total nitrogen concentration for the agronomic rate calculations that will be required for use of recycled water.

7.5.3. Recycled water monitoring requirements for total dissolved solids (TDS) are used to assess the salt concentration of the recycled water. This data will be evaluated to evaluate whether or not salt concentrations in the recycled water pose a threat to groundwater quality.

7.6. Receiving Water Monitoring

7.6.1. Surface Water

7.6.1.1. Receiving water monitoring is required to demonstrate compliance with the Receiving Water Limitations.

7.6.1.2. Consistent with Order No. R1-2017-0002, this Order requires weekly monitoring for fecal coliform bacteria, total coliform bacteria, and Enterococcus bacteria at Monitoring Location RSW-001.

7.6.2. Groundwater – Not Applicable
This Order does not require groundwater monitoring at this time.

CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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ATTACHMENT F – FACT SHEET F-53

7.7. Other Monitoring Requirements

7.7.1. Discharge Monitoring Report-Quality Assurance (DMR-QA) Study Program Under the authority of section 308 of the CWA (33 U.S.C. § 1318), U.S. EPA requires major and selected minor dischargers under the NPDES Program to participate in the annual DMR-QA Study Program. The DMR-QA Study evaluates the analytical ability of laboratories that routinely perform or support self-monitoring analyses required by NPDES permits. There are two options to satisfy the requirements of the DMR-QA Study Program: (1) The Permittee can obtain and analyze a DMR-QA sample as part of the DMR-QA Study; or (2) Per the waiver issued by U.S. EPA to the State Water Board, the Permittee can submit the results of the most recent Water Pollution Performance Evaluation Study from its own laboratories or its contract laboratories. A Water Pollution Performance Evaluation Study is similar to the DMR-QA Study. Thus, it also evaluates a laboratory’s ability to analyze wastewater samples to produce quality data that ensure the integrity of the NPDES Program. The Permittee shall ensure that the results of the DMR-QA Study or the results of the most recent Water Pollution Performance Evaluation Study are submitted annually to the State Water Board. The State Water Board’s Quality Assurance Program Officer will send the DMR-QA Study results or the results of the most recent Water Pollution Performance Evaluation Study to U.S. EPA’s DMR-QA Coordinator and Quality Assurance Manager.

7.7.2. Accelerated Monitoring Requirements. Table E-3 includes accelerated monitoring requirements for parameters that are required to be monitored daily, weekly, monthly, and annually.

7.7.3. Outfall Inspection. (MRP section 9.1). Consistent with Order No. R1-2017- 0002, this Order requires the Permittee to inspect and evaluate the outfall to determine the structural integrity and operational status of the outfall pipeline and structure once during the term of the permit. This requirement is necessary to demonstrate proper operation and maintenance of the POTW as required by 40 C.F.R. section 122.4, and to ensure that the calculated minimum probable initial dilution is not compromised as a result of unanticipated structural or operational changes in the outfall structure. The Permittee must submit an outfall evaluation/inspection work plan for Executive Officer approval in advance of conducting the evaluation/inspection. The work plan must identify methodologies for conducting the inspection which may include visual, camera, dye study, and/or other available methodologies.

7.7.4. Biological Survey. (MRP section 9.2). Consistent with Order No. R1-2017- 0002, this Order requires the Permittee to perform a biological survey of the outfall location once every 5 years.

7.7.5. Filtration Process Requirements (Monitoring Locations INT-001A and INT001B). Monitoring of the surface loading rate at Monitoring Location INT-001A is CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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necessary to demonstrate compliance with technology requirements set forth in DDW’s Alternative Treatment Technology Report for Recycled Water (September 2014 or subsequent). Monitoring of effluent turbidity of the tertiary filters at Monitoring Location INT-001B is required to demonstrate compliance with section 60301.320 of title 22 CCR filtration requirements for disinfected tertiary recycled water. These requirements are applicable if the Permittee produces and distributes recycled water.

7.7.6. Disinfection Process Monitoring for the Chlorine Disinfection System (Monitoring Location INT-002A). Chlorine disinfection system monitoring requirements at Monitoring Location INT-002A are included to assess compliance with the requirements specified in section 4.4.1 of the Order.

7.7.7. Disinfection Process Monitoring for UV Disinfection System (Monitoring Location INT-002B). UV disinfection system monitoring requirements at Monitoring Location INT-002B are included to assess compliance of the UV disinfection system with title 22 and the NWRI/AWWARF UV Disinfection Guidelines. These requirements apply if and when the Permittee establishes recycled water use site(s).

7.7.8. Sludge Monitoring (Monitoring Location BIO-001). New sludge monitoring requirements at Monitoring Location BIO-001 serve as a basis for the Permittee to develop the Sludge Handling and Disposal Activity Report that is required as part of the Annual Report pursuant to section 10.5.2.6 of the MRP. In addition, This Order establishes annual sludge monitoring requirements for priority pollutants to satisfy U.S. EPA pretreatment requirements.

7.7.9. Septage Station Monitoring. The Permittee does not currently accept or treat septage at the Facility, but is contemplating whether to develop a program for receiving septage at the Facility to satisfy the need for local septage disposal.

This Order includes monitoring requirements to characterize discharges of septage into the treatment system and to ensure that pollutants associated with domestic septage do not pass through or interfere with the operation or performance of the Facility. These requirements apply if and when the Permittee establishes a septage receiving program.

7.7.10. Notification and Reporting for Recycled Water Spills. Section 10.6.3 of the MRP includes reporting requirements for spills of tertiary treated water in excess of 50,000 gallons. This requirement implements Water Code section 13529.2 and applies if the Permittee produces and distributes recycled water.

7.7.11. Flow Monitoring. Section 1.4 of the MRP requires proper installation, calibration, operation, and maintenance of flow metering devices.

7.8. Special Studies and Additional Monitoring Requirements

7.8.1. Sanitary Sewer Evaluation Survey (MRP section 10.1.1). This Order requires the Permittee to evaluate the condition of its collection system and determine CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
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where and what rehabilitation and replacement efforts need to be completed to reduce inflow and infiltration (I/I) and flood risk. Treatment system flow data from the term of Order No. R1-2017-0002 indicates that I/I occurs at a rate greater than what is expected for the population size of the Crescent City and County Service Area collection system service areas. Furthermore, the Permittee identified within the Crescent City Climate Change Readiness Study (March 2021) that extreme precipitation events, increases in annual average precipitation, and more intense storm surge could exacerbate flooding and overflow frequency in the City’s collection system and negatively impact the WWTF treatment system. In order to ensure that Facility operations are not impacted, compliance with conditions of this Order are achieved, and receiving waters are not adversely impacted by permitted and unpermitted discharges, this Order requires the Permittee to submit a Sanitary Sewer Evaluation Survey.

8. PUBLIC PARTICIPATION
The Regional Water Board has considered the issuance of WDRs that will serve as an NPDES permit for the City of Crescent City, Wastewater Treatment Facility. As a step in the WDR adoption process, the Regional Water Board staff has developed tentative WDRs and has encouraged public participation in the WDR adoption process.

8.1. Notification of Interested Persons
In addition to the outreach identified in WDRs Section 2.6, the California Regional Water Quality Control Board, North Coast Region notified the Permittee and interested agencies and persons of its intent to prescribe WDRs for the discharge and provided an opportunity to submit written comments and recommendations.

Notification was provided through the following posting on the Regional Water Board’s Internet site at:
http://www.waterboards.ca.gov/northcoast/public_notices/public_hearings/npdes_ permits_and_wdrs.shtml on September 1, 2023.

The public had access to the agenda and any changes in dates and locations through the Regional Water Board’s website at:
http://www.waterboards.ca.gov/northcoast/public_notices/public_hearings/npdes_ permits_and_wdrs.shtml.

8.2. Written Comments
Interested persons were invited to submit written comments concerning these tentative WDRs as provided through the notification process. Comments were due to the Regional Water Board Executive Office electronically via e-mail to [email protected] or on disk (CD or DVD) in Portable Document Format (PDF) file in lieu of paper-sourced documents. The guidelines for electronic submittal of documents can be found on the Regional Water Board website at http://www.waterboards.ca.gov/northcoast.

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To be fully responded to by staff and considered by the Regional Water Board, the written comments were due at the Regional Water Board office by 5:00 p.m. on September 1, 2023

8.3. Public Hearing
The Regional Water Board held a public hearing on the tentative WDRs during its regular Board meeting on the following date and time and at the following location:

Date: December 12-13, 2023
Time: 9:00 a.m. or as announced in the Regional Water Board’s agenda Location: Regional Water Board Hearing Room
5550 Skylane Boulevard, Suite A
Santa Rosa, CA 95403
Interested persons were invited to attend. At the public hearing, the Regional Water Board heard testimony, pertinent to the discharge, WDRs, and permit. For accuracy of the record, important testimony was requested in writing.

8.4. Reconsideration of Waste Discharge Requirements
Any person aggrieved by this action of the Regional Water Board may petition the State Water Board to review the action in accordance with Water Code section 13320 and California Code of Regulations, title 23, sections 2050 and following.

The State Water Board must receive the petition by 5:00 p.m., within 30 calendar days of the date of adoption of this Order at the following address, except that if the thirtieth day following the date of this Order falls on a Saturday, Sunday, or state holiday, the petition must be received by the State Water Board by 5:00 p.m. on the next business day:

State Water Resources Control Board
Office of Chief Counsel
P.O. Box 100, 1001 I Street
Sacramento, CA 95812-0100
Or by email at [email protected] For instructions on how to file a petition for review, see the Water Quality Petitions Website at
http://www.waterboards.ca.gov/public_notices/petitions/water_quality/wqpetition_i nstr.shtml.

8.5. Information and Copying
The Report of Waste Discharge, other supporting documents, and comments received are on file and may be inspected at the address above at any time between 8:30 a.m. and 4:45 p.m., Monday through Friday. Copying of documents may be arranged through the Regional Water Board by calling (707) 576-2220.

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8.6. Register of Interested Persons
Any person interested in being placed on the mailing list for information regarding the WDRs and NPDES permit should contact the Regional Water Board, reference this facility, and provide a name, address, and phone number.

8.7. Additional Information
Requests for additional information or questions regarding this order should be directed to Matthew Herman at [email protected] or (707) 576-2683.

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Attachment F-1. Wastewater Treatment Facility RPA Summary Pollutant Units Qualifier MEC1 No.

Samples
No.

ND2 Co3 Cs4 X-obs5 Endpoint
Arsenic µg/L = 82.6 12 7 8 3 5.6533 2
Cadmium µg/L = 15.5 12 7 1 0 0.5167 2
Chromium VI µg/L = 6.3 5 3 2 0 0.21 3
Copper µg/L = 1,080 71 2 3 2 37.9333 1
Lead µg/L < 5 12 12 2 0 <0.1667 3
Mercury µg/L < 1 12 12 0.04 0.0005 <0.0338 3
Nickel µg/L = 116 71 8 5 0 3.8667 2
Selenium µg/L < 10 12 8 15 0 <0.3333 3
Silver µg/L = 139 12 712 0.7 0.16 4.7880 1
Zinc µg/L = 311 12 0 20 8 18.1000 2
Cyanide µg/L = 1.2 11 10 1 0 0.04 3
Total Chlorine Residual µg/L = 15,000 1,855 1,849 2 0 500 1 Ammonia (as N) µg/L = 33,300 538 0 600 0 1,110 1
Phenolic Compounds (nonchlorinated)µg/L < 11 5 5 30 0 <0.3667 3 Chlorinated Phenolics µg/L < 11 5 5 1 0 <0.3667 3
Endosulfan µg/L = 0.32 12 10 0.009 0 0.0107 1
Endrin µg/L = 2.84 12 10 0.002 0 0.0947 1
HCH µg/L < 0.0096 12 12 0.004 0 <0.0003 3
Acrolein µg/L < 2 5 5 220 0 <0.0667 3
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Pollutant Units Qualifier MEC1 No.

Samples
No.

ND2 Co3 Cs4 X-obs5 Endpoint
Antimony µg/L = 21 5 4 1,200 0 0.700 3
Bis(2-chloroethoxy)
methane
µg/L < 11 5 5 4.4 0 <0.3667 3
Bis(2-chloroisopropyl) ether µg/L < 11 5 5 1,200 0 <0.3667 3 Chlorobenzene µg/L < 1 5 5 570 0 <0.0333 3
Chromium (III) µg/L = 1.75 5 4 190,000 0 0.0583 3
Di-n-butyl Phthalate µg/L < 11 12 12 3,500 0 <0.3667 3
Dichlorobenzenes µg/L < 1 5 5 5,100 0 <0.0333 3
Diethyl Phthalate µg/L < 11 12 12 33,000 0 <0.3667 3
Dimethyl Phthalate µg/L < 11 12 12 820,000 0 <0.3667 3
4,6-dinitro-2-methylphenol µg/L < 55 5 5 220 0 <1.8333 3 2,4-dinitrophenol µg/L < 55 5 5 4 0 <1.8333 3
Ethylbenzene µg/L < 1 5 5 4,100 0 <0.0333 3
Fluoranthene µg/L < 11 5 5 15 0 <0.3667 3
Hexachlorocyclopentadiene µg/L < 28 5 5 58 0 <0.9333 3
Nitrobenzene µg/L < 28 5 5 4.9 0 <0.9333 3
Thallium µg/L < 10 5 5 2 0 <0.3333 3
Toluene µg/L = 7.69 5 0 85,000 0 0.2563 2
Tributylin µg/L < 0.003 5 5 0.0014 0 <0.0001 3
1,1,1-trichloroethane µg/L < 1 5 5 540,000 0 <0.0333 3
Acrylonitrile µg/L < 2 5 2 0.1 0 <0.0667 3
CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
ATTACHMENT F – FACT SHEET F-60
Pollutant Units Qualifier MEC1 No.

Samples
No.

ND2 Co3 Cs4 X-obs5 Endpoint
Aldrin µg/L < 0.0048 12 12 0.000022 0 <0.0002 3
Benzene µg/L < 1 5 5 5.9 0 <0.0333 3
Benzidine µg/L < 55 5 5 0.000069 0 <1.8334 3
Beryllium µg/L < 1 6 6 0.033 0 <0.0333 3
Bis(2-chloroethyl) Ether µg/L < 28 5 5 0.045 0 <0.9333 3 Bis(2-ethlyhexyl) Phthalate µg/L = 7.7 12 9 3.5 0 0.2567 2 Carbon Tetrachloride µg/L < 1 5 5 0.9 0 <0.0333 3
Chlordane µg/L < 0.05 12 12 0.000023 0 <0.0017 3
Chlorodibromomethane µg/L < 1 5 5 8.6 0 <0.0333 3
Chloroform µg/L = 2.44 5 0 130 0 0.0813 2
DDT µg/L = 0.21 12 10 0.00017 0 0.007 1
1,4-Dichlorobenzene µg/L < 1 5 5 18 0 <0.0333 3
3,3'-Dichlorobenzidine µg/L < 28 5 5 0.0081 0 <0.9333 3 1,2-Dichloroethane µg/L < 1 5 5 28 0 <0.0333 3
1,1-Dichloroethylene µg/L < 1 5 5 0.9 0 <0.0333 3
Dichlorobromomethane µg/L < 1 5 5 6.2 0 <0.0333 3
Dichloromethane µg/L < 2 5 5 450 0 <0.0667 3
1,3-Dichloropropene µg/L < 1 5 5 8.9 0 <0.0333 3
Dieldrin µg/L < 0.0048 12 12 0.00004 0 <0.0002 3
2,4-Dinitrotoluene µg/L < 11 5 5 2.6 0 <0.3667 3
1,2-Diphenylhydrazine µg/L < 11 5 5 0.16 0 <0.3667 3
CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
ATTACHMENT F – FACT SHEET F-61
Pollutant Units Qualifier MEC1 No.

Samples
No.

ND2 Co3 Cs4 X-obs5 Endpoint
Halomethanes µg/L < 1 5 5 130 0 <0.0333 3
Heptachlor µg/L = 0.14 12 11 0.00005 0 0.0047 1
Heptachlor Epoxide µg/L < 0.0096 12 12 0.00021 0 <0.0003 3 Hexachlorobenzene µg/L < 11 5 5 14 0 <0.3667 3
Hexachlorobutadiene µg/L < 11 5 5 2.5 0 <0.3667 3
Hexachloroethane µg/L < 11 5 5 730 0 <0.3667 3
Isophorone µg/L < 11 5 5 730 0 <0.3667 3
N-Nitrosodimethylamine µg/L < 11 5 5 7.3 0 <0.3667 3
N-Nitrosodi-N-Propylamine µg/L < 11 5 5 0.38 0 <0.3667 3 N-Nitrosodiphenylamine µg/L < 11 5 5 2.5 0 <0.3667 3
PAHs µg/L < 12 5 5 0.0088 0 <0.3668 3
PCBs µg/L < 0.5 5 5 0.000019 0 <0.0167 3
TCDD equivalents µg/L = 9.34E-08 5 0 3.9E-09 0 3.10E-09 2 1,1,2,2-Tetrachloroethane µg/L < 1 5 5 2.3 0 <0.0333 3
Tetrachloroethylene µg/L < 1 5 5 2 0 <0.0333 3
Toxaphene µg/L < 0.3 12 12 0.00021 0 <0.0100 3
Trichloroethylene µg/L < 1 5 5 27 0 <0.0333 3
1,1,2-Trichloroethane µg/L < 1 5 5 9.4 0 <0.0333 3
2,4,6-Trichlorophenol µg/L < 11 5 5 0.29 0 <0.3667 3
Vinyl Chloride µg/L < 1 5 5 36 0 <0.0333 3
CITY OF CRESCENT CITY ORDER NO. R1-2023-0039
WASTEWATER TREATMENT FACILITY NPDES NO. CA0022756
ATTACHMENT F – FACT SHEET F-62
Pollutant Units Qualifier MEC1 No.

Samples
No.

ND2 Co3 Cs4 X-obs5 Endpoint
Table Notes

1. MEC = Maximum Effluent Concentration

2. ND = Non-Detects

3. Co = The concentration (water quality objective) to be met at the completion of initial dilution (from Table 3 of the 2019 Ocean Plan).

4. Cs = The background seawater concentrations (from Table 5 of the 2019 Ocean Plan).

5. X-obs = The maximum concentration after complete mixing, calculated according to Step 4 of Appendix VI of the Ocean Plan using the permitted dilution ratio (Dm) of 50 as follows: X-obs = (Ce + Dm * Cs)/(Dm + 1), unless otherwise noted.

Appendix B
Time Schedule Order
North Coast Regional Water Quality Control Board
California Regional Water Quality Control Board
North Coast Region
TIME SCHEDULE ORDER No. R1-2025-0015

TO PROVIDE TIME SCHEDULES TO COMPLY WITH
ORDER No. R1-2023-0039

CITY OF CRESCENT CITY

WASTEWATER TREATMENT FACILITY
NPDES No. CA0022576
Del Norte County
WDID No. 1A84006ODN
The California Regional Water Quality Control Board, North Coast Region (hereafter Regional Water Board), finds:

1. The City of Crescent City (Permittee) is the owner of the City of Crescent City Wastewater Treatment Facility (Facility) located in Crescent City, California.

Operations Management International, Inc (OMI), a member of Jacobs Engineering Group took over responsibility for operations and maintenance of the Facility in September 2019.

2. The Facility discharges treated domestic, commercial, and industrial wastewater and wastewater to the Pacific Ocean, a water of the United States, in accordance with Waste Discharge Requirements (WDRs) Order No. R1-2023-0039 (Permit), adopted on December 12, 2023. The Permit also serves as the National Pollutant Discharge Elimination System (NPDES) permit (NPDES No. CA0022576). The Permit contains discharge prohibitions, effluent and receiving water limitations, compliance provisions and monitoring and reporting requirements.

3. The Permit established new bacteria effluent limitations related to enterococci and total coliform that apply to the discharge of treated wastewater from the Facility. The Permittee has been unable to comply with these final effluent limitations.

4. The Facility serves a population of approximately 15,372 within Crescent City and the surrounding County Service Area (CSA). The CSA has two sub-areas:
the Northwest area to the north of the City and the Bertsch Ocean View area to the east of the City.

Time Schedule Order - 2 - DRAFT
R1-2025-0015
Crescent City Wastewater Treatment Facility
The Facility is designed to treat an average dry weather flow of 1.86 million gallons per day (mgd), and a peak wet weather flow of 6.12 mgd of secondary treated wastewater. The Permittee has three significant industrial users, including a cheese factory and two breweries that are covered under local pretreatment permits to discharge to the Facility.

The treatment system consists of a mechanically cleaned screen, a flowmeasuring Parshall flume, and a wet well in which five pumps are available to lift the flow to the primary clarifiers. Primary treatment consists of two grit removal tanks followed by two rectangular primary clarifiers. Secondary treatment is provided by operating the rotating biological contactors (RBC) and membrane bioreactor (MBR) in parallel. The RBC system consists of three trains of fourstage, RBCs with a combined surface area of 1.2 million square feet. Flow from the RBCs reach three rectangular secondary clarifiers. Flows from the clarifiers and flow from the MBR unit are commingled and disinfected using sodium hypochlorite and dechlorinated using sodium bisulfite prior to discharge to the Pacific Ocean at Discharge Point 001.

5. The Permittee was previously regulated under WDR Order No. R1-2017-0002 (previous permit), adopted by the Regional Water Board on February 2, 2017, which also contained discharge prohibitions, effluent and receiving water limitations, compliance provisions, and monitoring and reporting requirements. In this previous permit, effluent limitations for fecal coliform bacteria were established based on U.S. EPA’s National Recommended Criteria for shellfish harvesting waters and are included in the National Shellfish Sanitation Program’s Guide for the Control of Molluscan Shellfish, 2015 Revision. (U. S. Department of Health and Human Services, Food and Drug Administration).

6. Historically, the Facility’s compliance monitoring for disinfection relied solely on fecal coliform and the Permittee was generally able to comply with these requirements. Six violations of effluent limitations for disinfection were identified during the term of Order No. R1-2017-0002. Under the new Order, disinfection effluent limitations are now based on requirements related to fecal coliform, enterococci, and total coliform. The Permittee reported 29 violations of disinfection effluent limits in the 2024 calendar year and has demonstrated that they cannot consistently comply with the enterococci and total coliform effluent limitations in their NPDES permit (Order No. R1-2023-0039). The Permittee’s initial evaluation of their treatment system indicates that bacteria exceedances are related to operation of the RBCs during periods of treatment flows greater than 1.1 million gallons per day (MGD).

7. On July 29, 2024, the Permittee submitted a Time Schedule Order Request for the Facility that expressed a concern that the Facility would continue to exceed the effluent limits for enterococci and total coliform bacteria and requested Time Schedule Order - 3 - DRAFT
R1-2025-0015
Crescent City Wastewater Treatment Facility
interim effluent limitations for the remainder of the current permit term to allow time for the Permittee to determine what corrective actions are necessary to ensure adequate disinfection of the wastewater is occurring at the Facility.

Regional Water Board staff identified that in order to provide the requested TSO, the Permittee must further provide the Regional Water Board a general task list that identifies the anticipated steps and a corresponding time schedule that will allow the Facility to come into compliance with the effluent limitations. The Permittee provided this additional information on March 5, 2025.

8. The Regional Water Board concurs that, based on the monitoring results from calendar year 2024, it is infeasible for the Permittee to immediately comply with final effluent imitations for enterococci and total coliform bacteria during periods of treatment flows greater than 1.1 MGD.

9. Terms in the Permit that the Permittees violate and/or threaten to violate are:

4.1.1.3.1. Enterococci

4.1.1.3.1.1. The 6-week rolling geometric mean of enterococci shall not exceed 30 colony forming units (CFU) per 100 mL; and

4.1.1.3.1.2. No sample shall exceed a CFU of 110 per 100 mL.

4.1.1.3.2. Total Coliform Organisms

4.1.1.3.2.1. The median value of total coliform bacteria shall not exceed an MPN of 70 per 100 mL in a calendar month; and

4.1.1.3.2.2. Not more than 10 percent of the samples collected in a calendar month shall exceed an MPN of 230 per 100 mL.

10.Water Code section 13300 states: "Whenever a regional board finds that a discharge of waste is taking place or threatening to take place that violates or will violate requirements prescribed by the regional board, or the state board, or that the waste collection, treatment, or disposal facilities of a discharger are approaching capacity, the board may require the discharger to submit for approval of the board, with such modifications as it may deem necessary, a detailed time schedule of specific actions the discharger shall take in order to correct or prevent a violation of requirements."
Time Schedule Order - 4 - DRAFT
R1-2025-0015
Crescent City Wastewater Treatment Facility

11.Water Code section 13267, subdivision (a) provides that the Regional Water Board may investigate the quality of any waters of the state within its region.

Water Code section 13267, subdivision (b) provides that the Regional Water Board, in conducting an investigation, may require a discharger to furnish, under penalty of perjury, technical or monitoring program reports. The reports required by this Order, pursuant to Water Code section 13267, are necessary to ensure that the future threat to water quality created by activities at the Facility are properly assessed and controlled. Due to the importance of protecting water resources as explained herein, the costs associated with developing the required reports and work plans bear a reasonable relationship to the benefits that will be obtained from having the necessary information for the Regional Water Board to properly regulate and monitor the Facility.

12.Water Code section 13383, subdivision (a) provides the Regional Water Board may establish monitoring, inspection, entry reporting, and record keeping requirements, as authorized by section 13160, 13376, or 13377 for any person who discharges, or proposes to discharge to navigable waters. Subdivision (b) provides that the Regional Water Board may require any person subject to this section to establish and maintain monitoring equipment or methods, including, where appropriate, biological monitoring methods, sample effluent as prescribed, and provide other information as may be reasonably required.

13.Pursuant to Water Code section 13385(j)(3), mandatory minimum penalties (MMPs) will not apply to future violations of the final effluent limitations for enterococci and total coliform bacteria, during the term of this Order, if:
a. A cease and desist or time schedule order is issued on or after July 1, 2000, and specifies the actions that the Permittee is required to take in order to correct the violations that would otherwise be subject to MMPs; b. The Regional Water Board finds that the Permittee is not able to consistently comply with one or more of the effluent limitations established in the waste discharge requirements applicable to the waste discharge because the effluent limitation is a new or more stringent regulatory requirement that has become applicable to the waste discharge after the effective date of the waste discharge requirements and after July 1, 2000, new or modified control measures are necessary in order to comply with the effluent limitation, and the new or modified control measures cannot be designed, installed, and put into operation within 30 calendar days; c. The Regional Water Board establishes a time schedule for bringing the waste discharge into compliance with the effluent limitations that is as short as possible, taking into account the technological, operational, and economic factors that affect the design, development, and implementation of the control measures that are necessary to comply with the effluent limitations, and where the time schedule exceeds one year, the time Time Schedule Order - 5 - DRAFT
R1-2025-0015
Crescent City Wastewater Treatment Facility
schedule includes interim requirements and actions and milestones leading to compliance.

Crescent City City CouncilMarch 2, 2026

Crescent City City Council
March 2, 2026