Visalia City Council
October 2, 2023

August 07, 2023

City of Visalia, Community Development Department
Paul Bernal, Director
315 E. Acequia Ave.

Visalia, CA 93291

Re: Carleton Acres Specific Plan – Biochemical Oxygen Demand and Total Suspended Solids Calculations

Mr. Bernal,

We have prepared the calculations below using the best available standards and practices that were able to find. Our calculations reference a report prepared by Provost and Prichard titled Local Discharge Limits Development, that was prepared for the City of Visalia in March 2011, see Appendix A. We have also utilized the City of Visalia’s Sewer Master Plan, December 2005, to calculate an assumed volume of effluent for the proposed project. See below for the equation that will be utilized to calculate the assumed BOD and TSS that will be generated by the proposed project.

The Carleton Acres Specific Plan is a new project being proposed by West Star Construction. The project is Located on Shirk Street, South of Shannon Parkway. The project is proposing to develop 28.76 Gross Acres of Commercial Parcel, 100.86 Gross Acres of Low Density Residential, 9.1 Gross Acres of Medium Density Residential, and 9.7 Gross Acres of High Density Residential. Using Table 3.4 from the City of Visalia’s Sewer Master Plan, the expected flow rates can be calculated using the Adjusted Flow Coefficients that have been provided.

Table 1: Breakdown of Land Use for Phase 1
Land Use Acreage Adjusted Flow Coefficient
(GPD/ga) Expected Flow (GPD)
Commercial 28.76 650 18,694
Low Density 100.86 800 80,688
Medium Density 9.1 1,300 11,830
High Density 9.7 2,000 19,400
Total Expected Flow: 130,612

Utilizing the equation and coefficients previously provided, we can calculate BOD as Follows:

𝐴𝐻𝐿𝑤𝑑𝑟 =
(8.34)(𝐶𝑤𝑑𝑟)(𝑄𝑤𝑤𝑡𝑓)
(1 − 𝑅𝑤𝑤𝑡𝑓)

Where:

𝐶𝑤𝑑𝑟 = 30
𝑄𝑤𝑤𝑡𝑓 = .131 𝑀𝐺𝐷
𝑅𝑤𝑤𝑡𝑓 = .9881

𝑩𝑶𝑫 = 𝟐𝟕𝟒𝟔. 𝟏𝟒 𝑳𝒃/𝑫𝒂𝒚

Utilizing the equation and coefficients previously provided, we can calculate TSS as Follows

𝐴𝐻𝐿𝑤𝑑𝑟 =
(8.34)(𝐶𝑤𝑑𝑟)(𝑄𝑤𝑤𝑡𝑓)
(1 − 𝑅𝑤𝑤𝑡𝑓)

Where:

𝐶𝑤𝑑𝑟 = 30
𝑄𝑤𝑤𝑡𝑓 = .131 𝑀𝐺𝐷
𝑅𝑤𝑤𝑡𝑓 = .9865

𝑻𝑺𝑺 = 𝟐𝟒𝟐𝟎. 𝟔𝟖 𝑳𝒃/𝑫𝒂𝒚

The estimated calculations of BOD and TSS for the remaining 312.3 Acres that are included in the second phase of the project, and map as part of the overall Specific Plan are shown below. Calculations utilize the same adjusted flow coefficients for Commercial (6.4 Acres), Low (217.5 Acres), Medium (66.7 Acres) and High (21.7 Acres) Density Residential listed in Table 3.4 and Table 1 above and includes the acreage for the Future Elementary School. These values should be analyzed again as the project develops to ensure accuracy.

𝑩𝑶𝑫 = 𝟔𝟒𝟖𝟏. 𝟒𝟒 𝑳𝒃/𝑫𝒂𝒚

𝑻𝑺𝑺 = 𝟓𝟕𝟏𝟑. 𝟐𝟕 𝑳𝒃/𝑫𝒂𝒚

Please review the calculations provided and if there are any additional questions or information needed, please feel free to contact me at (559)802-3052.

Steven J. Macias, PE
Civil Engineer

Appendix A

Local Discharge Limits Development

Visalia, California

DRAFT

March 16, 2011

Prepared for:

City of Visalia

Prepared by:

Provost & Pritchard Consulting Group
Clovis, California

COPYRIGHT 2011 by PROVOST & PRITCHARD CONSULTING GROUP

ALL RIGHTS RESERVED
Provost & Pritchard Consulting Group expressly rese rves its common law copyri ght and other applicable property rights to this document. This document is not to be reproduced, changed, or copied in any form or manner whatsoever, nor are they to be assigned to a th ird party without first obtaining the written permission and consent of Provost & Pritchard Consulting Group In the event of unauthorized reuse of the information contained herein by a third party, the third party shall hold the firm of Provost & Pritchard Consulting Group harmless, and shall bear the cost of Provost & Prit chard Consulting Group's legal fees associated with defending and enforcing these rights.

Local Discharge Limits Development City of Visalia

i
H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

TABLE OF CONTENTS

EXECUTIVE SUMMARY ................................................................................................. 1 1  INTRODUCTION ...................................................................................................... 1

1.1  WWTF Information ............................................................................................ 2 2  Pollutants of Concern ............................................................................................... 4

2.1  EPA POCs ........................................................................................................ 4

2.2  Existing Local Limits ......................................................................................... 5

2.3  Waste Discharge Requirement POCs ............................................................... 5

2.4  Other Reasons for POCs .................................................................................. 6

2.4.1  Water Quality Criteria ................................................................................. 6

2.4.2  Biosolids Land Application Criteria ............................................................ 6

2.4.3  Interference and Inhibition Criteria ............................................................. 7

2.4.4  Protection of Treatment Works, Collection System, and Workers ............. 7

2.5  Summary of Controlling Limits .......................................................................... 8

2.6  Evaluation of Existing Data ............................................................................... 9

2.7  Sampling Plan ................................................................................................. 11 3  Maximum Allowable Headworks Loadings ............................................................. 14

3.1  WWTF Removal Efficiencies ........................................................................... 14

3.2  Discharge Permit and Water Quality AHLs ..................................................... 16

3.3  Biosolids Disposal Based AHLs ...................................................................... 19

3.4  Inhibition Based AHLs ..................................................................................... 20

3.5  POC Maximum Allowable Headworks Loadings ............................................. 23 4  Designating Local Limits ........................................................................................ 25

4.1  Residential and Background Loadings ............................................................ 26

4.2  Septage Loadings ........................................................................................... 26

4.3  Maximum Allowable Industrial Loadings ......................................................... 27

4.3.1  Safety Factor and Growth Allowance ....................................................... 27

4.4  Local Limits Allocations ................................................................................... 27

4.4.1  Uniform Allocation .................................................................................... 27

Local Discharge Limits Development City of Visalia

ii
H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

4.4.2  IU Specific Allocation ............................................................................... 28

4.4.3  The Mass Proportion Allocation ............................................................... 28

4.5  Uniform Allocation of Local Limits ................................................................... 29

4.6  IU Specific Allocation of Local Limits .............................................................. 31

4.7  Comparison of Proposed and Existing Limits .................................................. 32

4.8  Protection of the Treatment Works, Collection System, and Workers ............. 33

4.8.1  Fume Toxicity .......................................................................................... 33

4.8.2  Oil and Grease ......................................................................................... 34

4.9  Public Participation ......................................................................................... 35

4.10  Implementation ............................................................................................... 35 5  Bibliography/References ........................................................................................ 36

APPENDIX A – WWTF Sampling Data
APPENDIX B – Bis (2-ethylhexyl) Phthalate Sampling Data APPENDIX C – WWTF Biosolids Data
APPENDIX D – Residential Background Sampling Data
APPENDIX E – Septage Hauler Sampling Data
APPENDIX F – Local Limits Calculations (Uniform Allocation) APPENDIX G – SIU Sampling Data
APPENDIX H – Local Limits Calculations (IU Specific Allocation)

Local Discharge Limits Development City of Visalia

iii
H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc LIST OF TABLES Page

Table ES-1: Local Limits Summary ................................................................................ 1 Table 1-1: Current SIUs ................................................................................................. 1 Table 2-1: EPA POCs .................................................................................................... 4 Table 2-2: Existing Local Limits POCs ........................................................................... 5 Table 2-3: WDR POCs ................................................................................................... 5 Table 2-4: Summary of Controlling Limits ...................................................................... 8 Table 2-5: Pollutants of Concern .................................................................................. 10 Table 2-6: Sampling Plan Information .......................................................................... 12 Table 3-1: Summary of WWTF Removal Efficiencies ................................................... 14 Table 3-2: WDR Based AHLs ....................................................................................... 16 Table 3-3: Water Quality (Chronic) Based AHLs .......................................................... 17 Table 3-4: Water Quality (Agricultural Water Supply) Based AHLs .............................. 18 Table 3-5: Summary of Water Quality Based AHLs ..................................................... 18 Table 3-6: Summary of Biosolids Disposal Based AHLs .............................................. 19 Table 3-7: Activated Sludge Inhibition Based AHLs ..................................................... 20 Table 3-8: Trickling Filter Inhibition Based AHLs .......................................................... 21 Table 3-9: Anaerobic Digester Inhibition (Conservative Pollutants) Based AHLs ......... 22 Table 3-10: Anaerobic Digester Inhibition (Non-Conservative Pollutants) Based AHLs22 Table 3-11: Summary Inhibition Based AHLs ............................................................... 23 Table 3-12: Maximum Allowable Headworks Loadings ................................................ 24 Table 4-1: Comparison of MAHLs with Average Headworks Loadings ........................ 25 Table 4-2: Uniform Allocation of Local Limits ............................................................... 30 Table 4-3: IU Specific Allocation of Local Limits ........................................................... 31 Table 4-4: Comparison of Existing and Proposed Local Limits .................................... 32 Table 4-5: Fume Toxicity Discharge Screening Levels ................................................ 34

Local Discharge Limits Development City of Visalia

iv
H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

ABBREVIATIONS

ACGIH ................................ American Conference of Governmental Industrial Hygienists AHL ................................................................................... Allowable Headworks Loading BOD ................................................................................... Biochemical Oxygen Demand CFR ...................................................................................... Code of Federal Regulations CTR ................................................................................................ California Toxics Rule EPA ........................................................ United States Environmental Protection Agency FOG .............................................................................................. Fats, Oils, and Grease GPD ........................................................................................................ Gallons Per Day IPP ................................................................................. Industrial Pretreatment Program IU................................................................................................................ Industrial User MAHL ................................................................ Maximum Allowable Headworks Loading MAIL ..................................................................... Maximum Allowable Industrial Loading MGD ............................................................................................. Million Gallons per Day NIOSH ............................................ National Institute for Occupational Safety and Health OSHA ...................................................... Occupational Safety and Health Administration POC .................................................................................................. Pollutant of Concern PPB .......................................................................................................... Parts Per Billion RWQCB ................................................................ Regional Water Quality Control Board SIU ............................................................................................ Significant Industrial User STEL ....................................................................................... Short Term Exposure Limit TSS ............................................................................................. Total Suspended Solids TWA-TLV ............................................. Threshold Limit Value – Time Weighted Average WDR ................................................................................ Waste Discharge Requirements WQ .............................................................................................................. Water Quality WQS ............................................................................................. Water Quality Standard WWTF ............................................................................... Wastewater Treatment Facility * .................................................................................................................... Multiplication

Local Discharge Limits Development City of Visalia
Page ES-1
H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

EXECUTIVE SUMMARY
The City of Visalia has an appr oved Industrial Pretreatment Program. As such, the City is required to maintain and enforce local limi ts on the significant industrial users that discharge to the City’s wastewat er treatment facility. The existing local limits were developed in 1992. The Regional Water Quality Control Board is requiring the City to re- evaluate their local limits.

A list of potential pollutants of concern wa s developed based on available sampling and treatment facility data. A sampling plan was developed and implemented to collect additional data necessary to perform the loca l limits evaluation. Us ing the information collected, the local limits were evaluated. The results of this evaluation are summarized in Table ES-1.

Table ES-1: Local Limits Summary
Pollutant Existing Local
Limit
Calculated Local
Limit
Allocation
Method
Proposed Local
Limit
Arsenic 0.05 mg/L 0.05 mg/L Uniform 0.05 mg/L
Boron 1.60 mg/L Not needed None
Cadmium 0.02 mg/L 0.08 mg/L IU Specific 0.02 mg/L
Chromium 3.44 mg/L 5.59 mg/L Uniform 3.44 mg/L
Copper 1.97 mg/L 2.14 mg/L IU Specific 1.97 mg/L
Cyanide 0.16 mg/L 36.97 mg/L IU Specific 0.16 mg/L
Lead 0.30 mg/L 0.48 mg/L IU Specific 0.30 mg/L
Mercury 0.02 mg/L 0.04 mg/L IU Specific 0.02 mg/L
Nickel 2.86 mg/L 5.53 mg/L IU Specific 2.86 mg/L
Silver 0.76 mg/L 12.40 mg/L IU Specific 0.76 mg/L
Zinc 0.64 mg/L 9.12 mg/L IU Specific 0.64 mg/L
Pentachlorophenol 0.15 mg/L Not needed None
Oil & Grease 200 mg/L 609 mg/L Uniform 200 mg/L
BOD5 18,161 lb/day 89,538 lb/day 1 Not applicable 18,161 lb/day TSS 41,633 lb/day 41,633 lb/day 1 Not applicable 41,633 lb/day 1Plant design capacity

City of Visalia
SECTION ONE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc 1 INTRODUCTION
The City of Visalia operates a wastewater treatment facility (WW TF) that collects the municipal wastewater generated from the City of Visalia and the Goshen Community Services District. The WWTF treats typica l domestic wastes as well as waste generated from commercial and indus trial users. Several of the industrial users served by the WWTF meet the definitio n of a Significant Industrial Users (SIUs) as defined by the United States Environment al Protection Agency (EPA) in 40 CFR 403.3. SIUs are defined as:
 Industries subject to Categorical Pr etreatment Standard s under 40 CFR 403.6 and 40 CFR chapter I, subchapter N;
 Any industry discharging an average of 25, 000 gallons per day (gpd) or more of process wastewater;
 Any industry that contributes a waste str eam that makes up 5 percent or more of the average dry weather hydraulic or organic capacity of the WWTF; or  Any industry designated by the Control Au thority to have a reasonable potential to adversely affect the WWTF’s operation.

Table 1-1 lists the current SIUs and the reason they are considered SIUs.

Table 1-1: Current SIUs
SIU Name SIU Reason SIU Name SIU Reason
Advanced Food
Products
Discharge volume Mission Un iform Discharge volume
Basic Chemical
Solutions
Categorical – 40
CFR 442
Pregis Innovative
Packaging
Potential to
impact WWTF
California Dairies Discharge volume Provisions Food Discharge volume ATC Plastics
(previously Heller
Performance Polymers)
Potential to impact
WWTF
Visalia Custom
Chrome
Categorical – 40
CFR 433
JM Eagle Potential to impact
WWTF
Voltage
Multipliers Inc.

Categorical – 40
CFR 469
Josten’s Print. And
Pub.

Potential to impact
WWTF
Western Milling Potential to
impact WWTF
Kawneer Company Categorical – 40
CFR 433

City of Visalia
SECTION ONE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Due to the fact that there are SIUs discharging to the WW TF, the City of Visalia is required to have an approved I ndustrial Pretreatment Progr am (IPP). The City’s IPP was approved by the Regional Water Quality Control Board (RWQCB) on May 5, 1983.

Part of the IPP requirements is the development and implem entation of local limits.

Local limits are designed to protect the oper ations of the WWTF and to ensure that its discharges, whether liquid, soli d, or air, comply with Stat e and Federal requirements.

The EPA published the Local Limits Development Guidance document in July 2004.

This document outlines the procedures to develop local limits. In developing local limits the following factors may need to be considered:
 the WWTF’s efficiency in tr eating and removing pollutants;  the WWTF’s history of complying wit h the Waste Discharge Requirements;  sludge disposal methods; and
 worker health and safety concerns.

The current local limits were developed in 1992. The purpose of this project is to re- evaluate those local limits and investigate the need for stricter or additional local limits.

1.1 WWTF Information
The WWTF treats sewage from the City of Visa lia and the community of Goshen. The combined population is approximat ely 125,000 with a service ar ea of 30 square miles.

The WWTF has a design capacity of 22 milli on gallons per day (MGD). The average flow for the period of January 2007 to August 2010 was 12.18 MG D, with a maximum one day flow of 14.79 MGD.

Sewage from the main trunklines enters two wet wells prior to entering the headworks of the WWTF. The headworks consists of bar screens. From the headworks, the flow goes to a set of four primar y sedimentation basins. Fr om the primary basins, the wastewater is sent to one of f our plastic media filled trickling filters. From the trickling filters the water is sent to the aerat ion basins. The aerat ion basins precede the secondary sedimentation basins. After t he sedimentation basins, the water is chlorinated prior to discharge. The WWTF has the ability to disc harge to Mill Creek, agricultural lands, and to onsite percolation ponds. A majority of the flow is discharged to Mill Creek, with the onsite percolati on ponds being the discharge point when Mill Creek is not used.

Sludge collected from the pr imary and secondary treatment pr ocesses is thickened in a pair of gravity belt thickeners. After thickeni ng, the sludge is fed to one of six anaerobic digesters. After digestion, liquid from the di gesters is discharged to one of two sludge pits for settling of solids. Supernatant from the sludge pits is pumped back to the headworks. The solids from the digesters are pumped to thirty unlined sludge drying City of Visalia
SECTION ONE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc beds. After 60 to 90 days, the sludge is transf erred to an onsite stockpile area. Once per year the stockpiled sludge is land applied to farmland in Merced County.

There are several streams from within the plant that are sent back to the wet wells prior to the headworks for treatment. These recycle streams are gravity thickener filtrate, secondary clarifier scum, supernatant from the sludge pits, decant from the sludge drying beds, and septage waste and chemical toilet waste. The samples obtained for the plant influent include these flows.

The WWTF accepts septage from licensed haul ers. The waste from the septage haulers is discharged at a point prior to the headworks to assure treatment by the entire WWTF process. The WWTF accepts approximat ely 11,599 gallons per day of septage from haulers.

The processes employed in the treatment process will affect certain pollutant local limits due to inhibition levels that can disrupt the treatment process. Additionally, the ability of the WWTF to remove pollutants will affect the local limits. The interference and inhibition values are detaile d in Section 2.4.3. The WWTF removal efficiencies are detailed in Section 3.1.

2 POLLUTANTS OF CONCERN
City of Visalia
SECTION TWO Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Pollutants of Concern (POCs) are those pollutants that need to be controlled to protect the WWTF, its workers, and the disposal of the treated wastewater effluent and biosolids. POCs are pollu tants that may cause pass th rough or interference at the WWTF, cause problems in the collection sy stem, or cause probl ems with the WWTF’s ability to dispose of the generated biosolids.

The following sections discuss the various reas ons a pollutant may be included in the list of POCs. There may be numerous reasons to consider a pollutant a POC. The fact that a pollutant is a POC does not mean that a local limi t must be developed for it.

Whether a local lim it is needed for a POC is discussed in Section 4. If a pollutant is determined to be a POC, data must be collected for it and a detailed evaluation of the POC must be performed.

2.1 EPA POCs
The EPA has established 15 pollutants that ar e often found in treatment plant effluent and biosolids. The EPA considers these 15 pollutants to be POCs and need to be evaluated as part of any local limits evaluation. These pollutants are listed in Table 2-1.

Table 2-1: EPA POCs
EPA POCs
Arsenic Cadmium
Chromium Copper
Cyanide Lead
Mercury Nickel
Silver Zinc
Molybdenum Selenium
BOD5 Total Suspended
Solids
Ammonia

2.2 Existing Local Limits
The City of Visalia has estab lished local limits for several pollutants. These pollutants are also considered POCs. Table 2-2 lists the pollutants that the City of Visalia currently regulates through a local limit.

Table 2-2: Existing Local Limits POCs
Local Limits POCs
Arsenic Boron
City of Visalia
SECTION TWO Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Cadmium Chromium
Copper Cyanide
Lead Mercury
Nickel Silver
Zinc Pentachlorophenol
Oil & Grease

2.3 Waste Discharge Requirement POCs
On September 21, 2006, the RWQCB issued Waste Discharge Requirements (WDR) for the City of Visalia WWTF. The WDR cont ains pollutant limitat ions that the WWTF must comply with on the discharge to Mill Creek , the Use Area (agricultural lands), or to the onsite disposal ponds. The pollutants that are regulated on the effluent are considered POCs. Table 2-3 lists the pollutants that have limitations listed in the WDR.

Table 2-3: WDR POCs
WDR POCs
BOD5 TSS
Oil & Grease Chlorides
Lead Ammonia

2.4 Other Reasons for POCs
There are several other reasons that a pollutant may be included on the POC list according to the EPA Guidance Manual, includi ng: water quality criteria, biosolid land application restrictions, and treatment plant inhibitions. There are numerous pollutants that are listed under these crit eria. However, to be consi dered a POC at least one of the following conditions must be met:
 The maximum pollutant concentration in th e plant effluent is more than one-half the allowable effluent concentration required to meet a water quality criteria limit;  The maximum pollutant concentration in the sludge is more than one-half the applicable biosolids residual disposal limit;
 The maximum pollutant concentration in a plant influent grab sample is more than one-half the inhibition threshold; or
 The maximum pollutant concentration in a plant influent gr ab composite sample is more than one-fourth the inhibition threshold.

2.4.1 Water Quality Criteria
City of Visalia
SECTION TWO Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc In the WDR for the WWTF, the RWQCB stated that Mill Creek’s beneficial uses are warm freshwater habitat, water contact recreation, and human health protection (consumption of aquatic organi sms only). There is normally no flow in Mill Creek upstream of the WWTF, so the discharge from the WWTF cons titutes the flow in Mill Creek. Therefore, there is no dilution of the WWTF effluent in Mill Creek. There are numerous constituents that have limitations based on the beneficial uses in Mill Creek.

Additionally, the State of Ca lifornia has limitations for water used for agricultural uses.

There are numerous constitu ents that have limitations based on the potential agricultural use of the treated effluent.

For both the beneficial and agricult ural use protection, only po llutants in concentrations that are greater than 50% of the water quality standard are considered POCs.

2.4.2 Biosolids Land Ap plication Criteria
The City of Visalia disposes of biosolids by land application. The WWTF must prohibit industrial users from dischargi ng pollutants that could c ause a violation of applicable sludge disposal regulations. The national sl udge standards are c ontained in 40 CFR 503. These limitations are based on human health and environmental risks and include numerical pollutant limit s, operational standards, m anagement practices, and requirements for sampling, record keeping, and reporting. The Stat e of California has adopted the federal standards in 40 CFR 503. Additionally, the State of California has land application standards set fo rth in Title 22. The pollutants contained in the 503 and Title 22 regulations are considered for evaluati on as a POC. In order to be considered a POC, the maximum pollutant concentration in the sludge must be more than one-half the applicable biosolids residual disposal limit.

2.4.3 Interference and Inhibition Criteria
The pretreatment regulations set forth by the EPA in 40 CFR 403.5( a) state that there must be prohibitions against the discharge of pollutants from an industrial user that may cause interference at the WWTF. Interf erence, as defined by the EPA, means a discharge that inhibits or disrupts a treatment plant and causes a violation of the WWTF’s WDR or biosolids sludge requirements. The EPA recomm ends that pollutants be considered POCs if they have caused inte rference in the past. Based on the City of Visalia WWTF historical data, there have been no pollutants that have caused interference at the plant in the past.

There are certain pollutants that may not cause an effluent discharge or biosolids disposal violation but that may cause di sruptions to the WWTF operations. The EPA Local Limits Development Guidance document contains a list of pollutants and inhibition concentrations for various treatment plant processes. The pollutants that have inhibition concentrations are considered POCs if the following criteria have been met:
 The maximum pollutant concentration in a plant influent grab sample is more than one-half the inhibition threshold; or
City of Visalia
SECTION TWO Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc  The maximum pollutant concentration in a plant influent gr ab composite sample is more than one-fourth the inhibition threshold.

2.4.4 Protection of Treatment Work s, Collection System, and Workers Explosive and flammable pollutants can threat en the integrity of the collection system and the health and safety of the WWTF wo rkers. Under the right conditions, the accumulation of such pollutants can produce ex plosions or fires. Local limits may be needed if these pollutants are expected to be discharged from industrial users.

The fume toxicity levels of certain pollutant s indicate the likelihood that a WWTF worker will suffer adverse health effects when the le vel is approached or ex ceeded. Volatile organic compound vapors are the major conc ern because they can be toxic and carcinogenic, and may produce chronic health affe cts after various periods of exposure.

The EPA Local Limits Development Guidance document list the concentrations for the various exposure levels set forth by the Nati onal Institute for Occupational Safety and Health (NIOSH), Occupational Health and Safety Administration (OSHA), and American Conference of Governmental Industrial Hygienists (ACGIH ). Local limits may be needed if these pollutants are expected to be discharged from industrial users at concentrations that may pose a risk to WWTF workers.

2.5 Summary of Controlling Limits
Based on the criteria discussed in Section 2, several potential pollutants of concern and their associated controlling lim it and inhibition limit were t abulated and summarized in Table 2-4.

Table 2-4: Summary of Controlling Limits
Primary Compound
Name
Controlling
Limit (ppb)  Source  Inhibition
Criteria (ppb)
Treatment
Process
Ammonia  3,500
Fresh Water Aquatic
4‐day average
(USEPA)  480,000(4)  Activated Sludge
Arsenic  100  Agricultural WQ Limit  100(1,2,3)  Activated Sludge Boron  700  Agricultural WQ Limit
Cadmium  0.27
Fresh Water Aquatic
4‐day average
(USEPA)  1,000(2,3)  Activated Sludge
Chloride  106,000  Agricultural WQ Limit
Chromium VI  1,000(2,3)  Activated Sludge
City of Visalia
SECTION TWO Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Copper  9.3
Fresh Water Aquatic
4‐day average (CTR)  1,000(1,2,3)  Activated Sludge
Cyanide (total)  5.2
Fresh Water Aquatic
4‐day average (CTR)  100(1,2,3)  Activated Sludge
Lead  3.2
Fresh Water Aquatic
4‐day average (CTR)  1,000(3)  Activated Sludge
Mercury  100(2,3)  Activated Sludge
Molybdenum  10  Agricultural WQ Limit
Nickel  52
Fresh Water Aquatic
4‐day average (CTR)  1,000(2,3)  Activated Sludge
Oil and Grease  10,000
Waste Discharge
Requirements
Selenium  5.0
Fresh Water Aquatic
4‐day average (CTR)
Silver  3.8
Fresh Water Aquatic
Instantaneous Max
(USEPA)  13,000(3)
Anaerobic
Digestion
Sodium  69,000  Agricultural WQ Limit
Zinc  120
Fresh Water Aquatic
4‐day average (CTR)  300(3)  Activated Sludge
Biochemical Oxygen
Demand (BOD)  30,000
Waste Discharge
Requirements
Primary Compound
Name
Controlling
Limit (ppb)  Source  Inhibition
Criteria (ppb)
Treatment
Process
Total Suspended Solids
(TSS)  30,000
Waste Discharge
Requirements
Chloroform  60  Exposure Limits  1,000(2)
Anaerobic
Digestion
Ethylbenzene  1,659  Exposure Limits  200,000(3)  Activated Sludge Toluene  2,075  Exposure Limits  200,000(3)  Activated Sludge 1) Jenkins, D.I., and Associates. 1984. Impact of Toxics on Treatment Literature Review. 2) Russell, L.L., C.B. Ca in, and D.I. Jenkins. 1984. Impacts of Priority Pollutants on Publicly Owned Treated Works Processes: A Literature Review. 1984 Purdue Industrial Waste Conference. 3) Anthony, R.M., and L.H. Briemburst. 1981. Determining Maximum Influent Concentrations of Priority Pollutants for Treatment Plants. Journal Water Pollution Control Federation 53(10):1457-1468. 4) U.S. EPA. 1986. Working Document; Interferences at Publicly Owned Treatment Works. September 1986.

2.6 Evaluation of Existing Data
The City of Visalia provided the following data for the local limits evaluation:
 Daily WWTF flow and influent/effluent sampling
City of Visalia
SECTION TWO Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc  WWTF Priority Pollutant scans
 Biosolids sampling
 SIU sampling
 Septage sampling
The sampling data provided above was for the period of January 2007 to September 2010. This data is shown in Appendices A, B, C, and F.

The existing data was compared to the values in Table 2-4 and the criteria in Section

2.5. Table 2-5 lists the pol lutants of concern and the r eason the pollut ant is being considered a POC.

City of Visalia
SECTION TWO Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Table 2-5: Pollutants of Concern

Pollutant Effluent
concentration
more than half of
effluent standard
Sludge
concentration
more than half of
sludge disposal
standard
Influent
concentration
more than 25% of
inhibition
concentration
Required by
EPA
Existing
local limit

BOD X X

TSS X X
Ammonia X

FOG X

Arsenic X X
Boron X
Cadmium X X
Chromium X X X
Copper X X X
Lead X X X
Mercury X X
Molybdenum X X X
Nickel X X
Selenium X X
Silver X X X
Sodium X
Zinc X X X X
Chloride X
Cyanide X X X X
Bis (2-ethylhexyl) phthalate X
Pentachlorophenol X
Tetrachloroethene X
Edosulfan II X
Endrin X
Heptachlor X
Bromodichloromethane X
Bromoform X
4,4' DDE X
City of Visalia
SECTION TWO Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

2.7 Sampling Plan
A review of the existing City of Visalia information showed there was additional information needed to complete the local limits evaluation.

The City of Visalia has no recent (last five years) monitoring data for residential or commercial users. A sampling plan wa s needed to address additional information needed for the evaluation. The residential sa mples were taken to cover every day of the week over at least a two week per iod (Week 1 – Monday, Wednesday, Friday, Sunday, Week 2 – Tuesday, Thursday, Saturday ). The exact dates were adjusted as needed to fit into existing staff work schedules and the availability of the laboratory to perform the required tests. For the samp ling at the WWTF, samples were obtained covering at least two different days. No sampling was performed within 48 hours of a measurable precipitation event. Commerc ial sampling required only one day of sampling. Table 2-6 lists t he pollutants that s hould be monitored, the location, number of samples, test methods, and the preferred detection limi t. Test methods listed are EPA test methods except those beginning with SM, which are St andard Methods test procedures.

Residential Sampling
The residential sampling was conducted to cover geographically diverse areas of the City. Based on the la yout of the wastewater collectio n system the following locations were sampled to provide the residential sampling information:
 Comstock
 Hillsdale
 Evergreen
 Mary and County Center
Commercial Sampling
A majority of the commercial establishm ents within the City are restaurants. The sampling for the commercial loading was conducted at a commercial shopping area that includes some restaurants. The follo wing location was sampled to represent commercial loading:
 Linwood
 Alley off Court
Treatment Plant
Samples and estimates of flow for the following processes were obtained:
 Plant influent
 Primary effluent
 Secondary effluent prior to chlorination
 Feed to anaerobic digesters
City of Visalia
SECTION TWO Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc  Plant final effluent

Treatment Plant Influent Return Flows
Samples and estimates of flow for the following processes were obtained:
 Scum funnels
 GBT Filtrate
 Supernatant Pit
 SRS (Septage) Station
In addition to the sampling information, the basis-of-design for the treatment plant is needed to ascertain the design loadings for t he non-conservative pollutants (ammonia, BOD, and TSS).

Table 2-6: Sampling Plan Information
Pollutant Residential
(seven sampling
events)
Commercial
(one sampling
event)
Treatment
Plant (two
sampling
events)
Treatment Plant
influent return
flow streams
(two sampling
events)
Test
Method
Preferred
Detection
Limit

BOD X X X X SM
5210B
2 mg/L

TSS X X X X SM
2540D

1 mg/L
Ammonia X X X X 350.1 1 mg/L
FOG (HEM) X X X X 1664 10 mg/L

Arsenic X X X 200.8 1 ug/L
Boron X X X 200.7 0.05 mg/L
Cadmium X X X 200.8 0.05 ug/L
Chromium X X X 200.8 1 ug/L
Copper X X X 200.8 2 ug/L
Lead X X X 200.8 0.5 ug/L
Mercury X X X X 1631 0.5 ng/L
Molybdenum X X X 200.8 1 ug/L
Nickel X X X 200.8 1 ug/L
Selenium X X X 200.8 1 ug/L
Silver X X X 200.8 1 ug/L
Pollutant Residential
(seven sampling
events)
Commercial
(one sampling
event)
Treatment
Plant (two
sampling
Treatment Plant
influent return
flow streams
Test
Method
Preferred
Detection
Limit
City of Visalia
SECTION TWO Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

events) (two sampling
events)
Sodium X X X 200.7 1 mg/L
Zinc X X X 200.8 5 ug/L
Chloride X X X X 300.0 2.0 mg/L
Cyanide X X X SM4500 5 ug/L
Bis (2-ethylhexyl) phthalate X X X 625 5 ug/L
Pentachlorophenol X X X 625 10 ug/L
Tetrachloroethene X X X 624 0.5 ug/L
Endosulfan II X X X 608 0.05 ug/L
Endrin X X X 608 0.05 ug/L
Heptachlor X X X 608 0.05 ug/L
Bromodichloromethane X X X 624 0.5 ug/L
Bromoform X X X 624 0.5 ug/L
4,4' DDE X X X 608 0.05 ug/L
City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc 3 MAXIMUM ALLOWABLE HEADWORKS LOADINGS
After determining the POCs (T able 2-5) and gathering the ad ditional sampling data, the maximum allowable headworks loadings (MAHLs ) can be calculated. The MAHL is the estimated upper limit of a par ticular pollutant loading to the WWTF intended to prevent pass through or interference. The MAHL fo r each POC is calculated by the following steps:

1. Calculation of WWTF removal efficiency for the POC;

2. Calculate the allowable headworks load ing (AHLs) for the various environmental criteria (such as WDR limits, water quality limits, sludge disposal limits, inhibition values);

3. Designate the MAHL as the most stringent allowabl e headworks loading for the POC.

3.1 WWTF Removal Efficiencies
Based on the sampling data co llected from the City of Vi salia WWTF, the removal efficiencies for the POCs were calculated. The removal efficiencies shown in Table 3-1 are the average removal percentages for eac h POC. The detailed data used to calculate the removal efficiencies is cont ained in Appen dix A. For purposes of calculating the removal efficiencies, any reported concentration that was below the detection limit was assumed to be half the detection limit. Any negative removal efficiencies were assumed to be zero.

Table 3-1: Summary of WWTF Removal Efficiencies
POC Removal Efficiency Number of
Samples
BOD 98.81% 567
TSS 98.65% 919
Ammonia 44% 88
FOG 96% 4
Arsenic 29% 4
Boron 2% 6
Cadmium 67% 1 6
Chromium 20% 6
Copper 88% 6
Lead 62% 6
City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc POC Removal Efficiency Number of
Samples
Mercury 95% 5
Molybdenum 35% 4
Nickel 37% 6
Selenium 40% 6
Silver 40% 6
Sodium 3% 5
Zinc 79% 6
Chloride 0% 5
Cyanide 69% 1 5
Bis (2-ethylhexyl) phthalate 83% 6
Pentachlorophenol 0% 2 6
Tetrachloroethene 0% 2 6
Endosulfan II 0% 2 4
Endrin 0% 2 5
Heptachlor 0% 2 5
Bromodichloromethane 0% 2 6
Bromoform 0% 2 6
4,4’ DDE 0% 2 6
1EPA median removal percentage used since most results were below detection limit.
2Influent and Effluent samples were all below detection limit.

The sampling plan results showed that for all samples, pentachlorophenol, tetrachloroethene, endosulfan II, endrin, heptachlor, bromodichloromethane, bromoform, and 4,4’ DDE were not present in the infl uent or effluent of the WWTF.

Therefore, these pollutants were removed from consideration as POCs.

Bis (2-ethylhexyl) phthalate was detected abov e the detection limit in some of the regular monthly WWTF effluent samples. However, the field blanks obtained during those sampling events showed concentrations great er than the effluent sample values.

This data is shown in App endix B. Based on this information, the effluent concentrations for bis (2-ethylhexyl) phthalate are considered to be below the detection limit. Therefore, bis (2-ethylhexyl) phthala te was removed from consideration as a POC.

City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc The sampling plan results also showed that the return of WWTF recycle flows to the headworks had a minimal impact on the headwor ks loading to the WWTF. The return flows are from the scum funnel s, GBT filtrate, supernatant pit and the septage receiving station. These flows are estimated to make up approximatel y 2% of the headworks flow.

3.2 Discharge Permit and Water Quality AHLs
The RWQCB issued the WWTF Waste Dischar ge Requirements (WDR) that regulates the discharge from the plant. The AHL for POCs with W DR limitations is shown in Equation 1.

Equation 1 – AHL based on WDR limits
AHLwdr = (8.34)(Cwdr)(Qwwtf)
(1-Rwwtf)
Where:

AHLwdr = AHL based on WDR limit, lb/day
Cwdr = WDR permit limit, mg/L
Qwwtf = WWTF average flow rate, MGD
Rwwtf = Plant removal efficiency, as decimal

8.34 = Conversion factor
Table 3-2 shows the allowable headworks loading for the POCs based upon the limitations contained in the WDR.

Table 3-2: WDR Based AHLs
WWTF WDR Select Removal Allowable
Pollutant Flow Limit Removal Efficiency Headworks
(MGD) (mg/l) Efficiency (%) (lbs/day)
(Qwwtf) (Cwdr) (from list) (Rwwtf)
Lead 12.18 0.05 User Entered 62.19 13.434
Ammonia 12.18 25 User Entered 43.89 4525.7652
BOD 12.18 30 User Entered 98.81 256354.5218
TSS 12.18 30 User Entered 98.65 226555.1037
The WDR issued does not contain limitations for all the POCs mentioned in Table 2-5.

For the pollutants without lim itation in the W DR, the EPA guidance recommends using AHLs based on State or Federal Water Q uality Standards. The water quality standards can be based upon short term aquatic life affects (acute) or long term affects (chronic).

Water quality standards can also be based upon human health effects. The human health effects can be from drinking of the wa ter, recreational use of the water, or consumption of aquatic life. According to the WDR, the discharge to Mill Creek is City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc protected for agricultural water supply, wate r contact and noncontact water recreation, warm freshwater habitat, and groundwater re charge. The criteria used for this comparison is discussed in Section 2.4. The AHL for POCs that have water quality standards is shown in Equation 2.

Equation 2 – AHL based on Water Quality limits
AHLwq = (8.34)[(Cwq)*(Qstr+Qwwtf) – (Cstr*Qstr)]
(1-Rwwtf)
Where:

AHLwq = AHL based on water quality criteria, lb/day
Cwq = State or Federal water quality standard, mg/L
Cstr = Receiving stream background concentration, mg/L
Qwwtf = WWTF average flow rate, MGD
Qstr = Receiving stream (upstream) flow rate, MGD
Rwwtf = Plant removal efficiency, as decimal

8.34 = Conversion factor
The equation allows for inst antaneous mixing of the discharge with the receiving stream. Since there is normally no flow in Mill Creek upstream of the WWTF discharge, the receiving stream concentra tion and receiving stream flow were considered to be zero.

Table 3-3 shows the allowabl e headworks loading for the POCs based upon the water quality standards.

Table 3-3: Water Quality (Chronic) Based AHLs
WWTF Receiving
Receiving
Stream Chronic Removal Allowable
Pollutant Flow
Stream
Flow Concentration WQS Efficiency Headworks
(MGD) (MGD) (mg/l) (mg/l) (%) (lbs/day)
(Qwwtf) (Qstr1) (Cstr) (Cwq) (Rwwtf)
Arsenic 12.18 0.00 0 0.15000 28.98 21.4539
Cadmium 12.18 0.00 0 0.00027 67.00 0.0831
Copper 12.18 0.00 0 0.00930 88.14 7.9671
Cyanide 12.18 0.00 0 0.00520 69.00 1.7039
Lead 12.18 0.00 0 0.00320 62.19 0.8598
Mercury 12.18 0.00 0 0.00077 95.17 1.6183
Nickel 12.18 0.00 0 0.05200 37.22 8.4145
Selenium 12.18 0.00 0 0.00500 40.26 0.8501
Zinc 12.18 0.00 0 0.12000 79.37 59.0870
Ammonia 12.18 0.00 0 25.00000 43.89 4525.7652
Chloride 12.18 0.00 0 230.00000 0.00 23363.676
City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Table 3-4 shows the allowable headworks loading for the POCs based upon the agricultural water supply standards.

Table 3-4: Water Quality (Agricultural Water Supply) Based AHLs WWTF Receiving
Receiving
Stream Agricultural Removal Allowable
Pollutant Flow Stream Flow C onc WQS Efficiency Headworks (MGD) (MGD) (mg/l) (mg/l) (%) (lbs/day)
(Qwwtf) (Qstr2) (Cstr) (Cwq) (Rwwtf)
Arsenic 12.18 0.00 0 0.10000 28.98 14.3026
Molybdenum 12.18 0.00 0 0.01000 35.00 1.5628
Boron 12.18 0.00 0 0.70000 1.85 72.4485
Chloride 12.18 0.00 0 106.00000 0.00 10767.6072
Table 3-5 shows a summary of the water qual ity based AHLs. The most restrictive (lowest) loading for each POC has been highlighted.

Table 3-5: Summary of Water Quality Based AHLs
Allowable Allowable Allowable Allowable
Pollutant Headworks Headwo rks Headworks Headworks
(NPDES) (CHRONIC) (ACUTE) (WATER QUALITY)
(lbs/day) (lbs/day) (lbs/day) (lbs/day)
Arsenic - 23.4539 14.3026 14.3026
Cadmium - 0.0831 - 0.0831
Copper - 7.9671 - 7.9671
Cyanide - 1.7039 - 1.7039
Lead 13.4337 0.8598 - 0.8598
Mercury - 1.6183 - 1.6183
Molybdenum - - 1.5628 1.5628
Nickel - 8.4145 - 8.4145
Selenium - 0.8501 - 0.8501
Zinc - 59.0870 - 59.0870
Ammonia 4525.7652 4525.7652 - 4525.7652
BOD 256354.5218 - - 256354.5218
TSS 226555.1037 - - 226555.1037
Boron - - 72.4485 72.4485
Chloride - 23363.6760 10767.6072 10767.6072
FOG 22573.6000 - - 22573.6000

3.3 Biosolids Disposal Based AHLs
City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc The biosolids produced at the treatment plant are eventually land applied. The Federal sludge disposal regulations, 40 CFR Part 503, establish limitations for certain metals that are normally seen in industrial discharges. Additionally, California Title 22 contains additional pollutant limitations on the land application of biosolids. These limitations are converted to AHLs for the POCs using Equation 3.

Equation 3 – AHL based on Biosolids Disposal limits
AHLbsol = (0.0022)(Cbsol)(Qbsol)
(1-Rwwtf)
Where:

AHLbsol = AHL based on biosolids disposal limit, lb/day Cbsol = Biosolids limitation, mg/kg dry sludge
Qbsol = Total sludge flow to disposal, dry metric tons per day Rwwtf = Plant removal efficiency, as decimal

0.0022 = Conversion factor

Table 3-6 shows a summary of the biosolid s disposal based AHLs. Where a limitation existed for a pollutant in both 503 and Title 22, the most string ent (lowest) limit is used in the table. Details of the Title 22 land application calculati ons are contained in Appendix C.

Table 3-6: Summary of Biosolids Disposal Based AHLs
WWTF Sludge Flow Land Application Removal Allowable
Pollutant Flow to Disposal Standard Efficiency Headworks (MGD) (MTD) (mg/kg) (%) (lbs/day)
(Qwwtf) (Qbsol) (C bsol) (Rwwtf) (Lhw)
Arsenic 12.18 4.358636364 41(1) 28.98 1.3568
Cadmium 12.18 4.358636364 17.86074(2) 67.00 0.2556
Chromium 12.18 4.358636364 2833.905(2) 20.41 133.173
Copper 12.18 4.358636364 1500(1) 88.14 16.3185
Lead 12.18 4.358636364 300(1) 62.19 4.6255
Mercury 12.18 4.358636364 17(1) 95.17 0.1713
Molybdenum 12.18 4.358636364 18(1) 35.00 0.4931
Nickel 12.18 4.358636364 420(1) 37.22 10.8190
Selenium 12.18 4.358636364 35.21127(2) 40.26 0.8387
Silver 12.18 4.358636364 566.781(2) 40.42 13.4456
Zinc 12.18 4.358636364 2800(1) 79.37 33.8280
(1)Based on 40 CFR Part 503 regulations.(2)Based on California Title 22 calculations.

City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

3.4 Inhibition Based AHLs
Certain pollutant concentrations in wast ewater or sludge can cause operational problems for biological treatment processes. The City of Visalia WWTF operates the following biological processes that may be subject to inhibi tion issues: activated sludge, trickling filters, and anaerobi c sludge digestion. The WW TF has not had historical issues with pollutants causing upsets of the biological processes. Th e EPA guidance document contains inhibition values for po llutants that have the potential to upset biological treatment processes. These inhibition limitations are converted to AHLs for the POCs using Equation 4, Equation 5, and Equation 6.

Equation 4 – AHL based on Activated Sludge Inhibition Values AHLact = (8.34)(Cact)(Qwwtf)
(1-Rprim)
Where:

AHLact = AHL based on activated sludge inhibition, lb/day Cact = Inhibition criterion for activated sludge, mg/L
Qwwtf = WWTF average flow rate, MGD
Rprim = Removal efficiency from headworks to primary treatment effluent, as decimal (assumed using EPA removal values)

8.34 = Conversion factor

Table 3-7 shows the calculated AHLs based on activated sludge inhibition values.

Table 3-7: Activated Sludge Inhibition Based AHLs

WWTF
Activated
Sludge Removal Allowable
User
Entered
Pollutant Flow Inhibition Level Efficiency Headworks Removal (MGD) (mg/l) (%) (lbs/day) Efficiency
(Qwwtf (Cact) (Rprim) (Lhw) (%)
Arsenic 12.18 0.1 91.90 125.4089 91.90
Cadmium 12.18 1 90.00 1015.812 90.00
Chromium 12.18 1 49.30 200.3574 49.30
Copper 12.18 1 96.10 2604.646 96.10
Cyanide 12.18 0.1 90.00 101.5812 90.00
Lead 12.18 1 80.00 507.9060 80.00
Mercury 12.18 0.1 93.20 149.3841 93.20
Nickel 12.18 1 55.20 226.7438 55.20
Zinc 12.18 0.3 96.00 761.8590 96.00
Ammonia 12.18 480 0.00 48758.98 0.00
City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Equation 5 – AHL based on Trickling Filter Inhibition Values AHLtric = (8.34)(Ctric)(Qwwtf)
(1-Rprim)
Where:

AHLtric = AHL based on trickling filter inhibition, lb/day Ctric = Inhibition criterion for trickling filters, mg/L Qwwtf = WWTF average flow rate, MGD
Rprim = Removal efficiency from headworks to primary treatment effluent, as decimal (assumed using EPA removal values)

8.34 = Conversion factor

Table 3-8 shows the calculated AHLs based on trickling filter inhibition values.

Table 3-8: Trickling Filter Inhibition Based AHLs

WWTF
Trickling
Filter Select Removal Allowable
EPA
Guidance
Pollutant Flow
Inhibition
Level Removal Efficiency Headworks Removal
(MGD) (mg/l) Efficiency (%) (lbs/day) Efficiency
(Qwwtf) (Ctric) (from list) (Rprim) (Lhw) (%)
Chromium 12.18 3.5
Default (Through
Trick. Fil.) 55.00 790.076 55.00
Cyanide 12.18 30
Default (Through
Trick. Fil.) 59.00 7432.77 59.00

Equation 6 – AHL based on Anaerobic Digestion Inhibition Values (Conservative Pollutants) AHLdig = (8.34)(Cdiginb)(Qdig)
Rwwtf
Where:

AHLdig = AHL based on anaerobic digestion inhibition, lb/day Cdiginb = Inhibition criterion for sludge digester, mg/L Qdig = Sludge flow rate to digester, MGD
Rwwtf = Plant removal efficiency, as decimal

8.34 = Conversion factor

Table 3-9 shows the calculated AHLs based on anaerobic digester inhibition values for conservative pollutants.

Table 3-9: Anaerobic Digester Inhibition (Conservative Pollutants) Based AHLs

City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc WWTF Sludge Flow Anaerobic Digester Removal Allowable
Pollutant Flow to Digester Inhibi tion Level Efficiency Headworks (MGD) (MGD) (mg/l) (%) (lbs/day)
(Qwwtf) (Qdig) (Ccrit) (Rwwtf) (Lhw)
Arsenic 12.18 0.03833 1.6 28.98 1.7651
Cadmium 12.18 0.03833 20 67.00 9.5425
Chromium 12.18 0.03833 130 20.41 203.661
Copper 12.18 0.03833 40 88.14 14.5071
Lead 12.18 0.03833 340 62.19 174.764
Nickel 12.18 0.03833 10 37.22 8.5876
Silver 12.18 0.03833 13 40.42 10.2811
Zinc 12.18 0.03833 400 79.37 161.1051

Equation 7 – AHL based on Anaerobic Digestion Inhibition Values (Non-Conservative Pollutants) AHLdig = (Cdiginb) * Linf
(Cdig)
Where:

AHLdig = AHL based on anaerobic digestion inhibition, lb/day Cdiginb = Inhibition criterion for sludge digester, mg/L Cdig = Existing pollutant level in sludge, mg/L
Linf = WWTF influent loading, lb/day

Table 3-10 shows the calculated AHLs based on anaerobic digester inhibition values for non-conservative pollutants.

Table 3-10: Anaerobic Digester Inhibi tion (Non-Conservative Pollutants) Based AHLs

WWTF
Average
Influent Average
Digester
Pollutant
Anaerobic
Digester Allowable
Pollutant Flow Conc Influent Load Conc Inhibition Level Headworks (MGD) (mg/l) (lbs/day) (mg/l) (mg/l) (lbs/day)
(Qwwtf) (Linf) (Cdig) (Cdiginb) (Lhw)
Cyanide 12.18 2.50 253.9530 3.73 1 68.0839
Ammonia 12.18 95.50 9701.0046 4214.25 1500 3452.929
Table 3-11 shows a summary of the inhibition based AHLs. The most restrictive (lowest) loading for each POC has been highlighted.

Table 3-11: Summary Inhibition Based AHLs
City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Allowable Allowable Allowable Allowable Allowable
Pollutant Headworks Headworks Headworks Headworks Headworks

(ACT.

SLUDGE)
(TRICK.

FILTER)
(DIG. -
CONSERV.)
(DIG. - NON-
CONS.) (INHIB)
(lbs/day) (lbs/day) (lbs/day) (lbs/day) (lbs/day)
Arsenic 125.4089 - 1.7651 - 1.7651
Cadmium 1015.812 - 9.5425 - 9.5425
Chromium 200.3574 790.0760 203.6605 - 200.3574
Copper 2604.646 - 14.5071 - 14.5071
Cyanide 101.5812 7432.770 - 68.0839 68.0839
Lead 507.9060 - 174.7642 - 174.7642
Mercury 149.3841 - - - 149.384
Nickel 226.7438 - 8.5876 - 8.5876
Silver - - 10.2811 - 10.2811
Zinc 761.8590 - 161.1051 - 161.1051
Ammonia 48758.97 - - 3452.9292 3452.92

3.5 POC Maximum Allowa ble Headworks Loadings
The maximum allowable headwor ks loading is the lowest of the AHLs calculated for each POC. Influent loadings below the MAHL will lead to compliance with the AHLs based on all environmental and treatment plant criteria. Table 3-12 shows a summary of AHLs as well as the MAHL for each POC.

City of Visalia
SECTION THREE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Table 3-12: Maximum Allowable Headworks Loadings
Allowable Allowable Allowable Maximum
Pollutant Headworks Headworks Headworks Allowable
(WATER QUALITY) (INHIBITION) (SLUDGE) Headworks
(lbs/day) (lbs/d) (lbs/d) (MAHL - lbs/d)
Arsenic 14.3026 1.7651 1.3568 1.3568
Cadmium 0.0831 9.5425 0.2556 0.0831
Chromium - 200.3574 133.1733 133.1733
Copper 7.9671 14.5071 16.3185 7.9671
Cyanide 1.7039 68.0839 - 1.7039
Lead 0.8598 174.7642 4.6255 0.8598
Mercury 1.6183 149.3841 0.1713 0.1713
Molybdenum 1.5628 - 0.4931 0.4931
Nickel 8.4145 8.5876 10.8190 8.4145
Selenium 0.8501 - 0.8387 0.8387
Silver - 10.2811 13.4456 10.2811
Zinc 59.0870 161.1051 33.8280 33.8280
Ammonia 4525.7652 3452.9292 - 3452.9292
BOD 256354.5218 - - 256354.5218
TSS 226555.1037 - - 226555.1037
Boron 72.4485 - - 72.4485
Chloride 10767.61 - - 10767.61
FOG 22573.6000 - - 22573.6000
City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc 4 DESIGNATING LOCAL LIMITS
After the calculation of t he maximum allowable headworks loadings for the POCs, the POCs that require a local limit must be determined. The EPA guidance document recommends developing local limits for those POCs where the aver age influent loading exceeds 60% of the MAHL. Table 4-1 shows a comparison of MAHLs with the average headworks loadings for each POC. The high lighted POCs are those whose average influent loadings exceed 60% of the MAHL and will be evaluated for local limits.

Table 4-1: Comparison of MAHLs with Average Headworks Loadings Maximum Average Average
Pollutant Allowable Influent Percent
Headworks Loading Loaded
(MAHL - lbs/d) (lbs/day) (%)
Arsenic 1.3568 1.0959 80.7732
Cadmium 0.0831 0.1060 127.5781
Chromium 133.1733 0.4472 0.3358
Copper 7.9671 4.0814 51.2283
Cyanide 1.7039 0.2541 14.9108
Lead 0.8598 0.4302 50.0408
Mercury 0.1713 0.0058 3.3700
Molybdenum 0.4931 0.2642 53.5811
Nickel 8.4145 0.5098 6.0590
Selenium 0.8387 0.0825 9.8349
Silver 10.2811 0.7183 6.9870
Zinc 33.8280 15.8541 46.8668
Ammonia 3452.9292 2471.1932 71.5680
BOD 256354.5218 33233.2884 12.9638
TSS 226555.1037 35048.0272 15.4700
Boron 72.4485 0.1075 0.1483
Chloride 10767.6072 5447.2961 50.5897
FOG 22573.6000 5793.2500 25.6638
Based on the information shown in Table 4-1, there is no local limit necessary for molybdenum, selenium, boron, and chloride. No local limit is necessary for ammonia since a review SIU data for ammonia shows little or no ammonia in the industrial discharge and the influent loading is 71.6% of the MAHL for ammonia.

City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

4.1 Residential and Background Loadings
There are many other sources of wastew ater to the WWTF besides the regulated industrial user flows. Thes e other sources include domest ic (residential) waste, storm water, inflow and infiltration, and commercial dischargers. Because the WWTF does not control the discharges from these sour ces, the loading c ontributed from these uncontrolled sources must be deducted from the MAHL to determine the loading available for industrial dischargers.

The City of Visalia has a separated sewer system so storm water is conveyed via a dedicated piping system to minimize the volu me of storm water entering the sewer collection system and the WWTF. Additionally, the collection system does not have significant volumes of inflow and infiltration. Therefore, the loadings from storm water and inflow and infiltration to the WWTF are considered to be negligible.

The City of Visalia has performed sampling in residential and commercial areas to determine the expected loadings from these sour ces. This sampling data is contained in Appendix D. The loading from these sources is calculated by Equation 8.

Equation 8 – Residential and Background Loading Calculation Lunc = (Cunc) * (Qunc) * 8.34
Where:

Lunc = Uncontrolled loading, lb/day
Cunc = Uncontrolled pollutant concentration, mg/L
Qunc = Uncontrolled flow rate, MGD

8.34 = Unit conversion factor

4.2 Septage Loadings
The City of Visalia WWTF accepts septage waste from licensed haulers. Since the septage haulers are not subject to local lim its like industrial user s, the loading the WWTF receives from septage haulers needs to be subtracted from the MAHLs when determining the loadings available for industri al users. The City of Visalia samples some septage discharges and records the volu me of septage rece ived. This septage hauler information is shown in Appendix E. E quation 9 is used to calculate the loading from septage haulers.

Equation 9 – Septage Loading Calculation
Lsep = (Csep) * (Qsep) * 8.34
Where:

Lsep = Septage loading, lb/day
Csep = Septage pollutant concentration, mg/L
Qsep = Septage flow rate, MGD

8.34 = Unit conversion factor
City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

4.3 Maximum Allowable Industrial Loadings
Maximum Allowable Industrial Loadings (MAILs) are the amount of pollutant loadings that the WWTF can receive from controlled sources (permitted industrial users). The MAIL for each pollutant is calculated by Equation 10.

Equation 10 – MAIL Calculation
MAIL = MAHL (1-SF) – (Lunc+SW+GA)
Where:

MAIL = Maximum allowable industrial loading, lb/day
MAHL = Maximum allowable headworks loading, lb/day
SF
= Safety factor, decimal
Lunc = Loadings from uncontrolled sources, lb/day
SW = Loadings from septage waste, lb/day
GA = Growth allowance, lb/day

4.3.1 Safety Factor and Growth Allowance
The safety factor is a percent age of the MAHL set aside to account for variability in the data analyzed and other uncertainties. T he EPA recommends at least a 10 percent safety factor be used. For the purposes of this local limits study, a 10 percent safety factor will be used for all pollutants.

Growth allowance is a part of the MAHL that can be held reserve to allow for potential growth or expansion within the service area. The growth allowance is normally used for those pollutants that the WWTF was designed to remove, such as BOD, TSS, and ammonia. The City of Visalia does not know of any major growth or expansions to the wastewater collection system. However, five percent will be set aside to allow for any growth that may occur during the life of the local limits. Setting aside the five percent will allow some growth without the need to revise the local limits.

4.4 Local Limits Allocations
There are two common approaches to allocati ng the available MAIL to the significant industrial users. The two common methods are uniform allocation and Industrial User specific allocation. Different allocation methods can be used for each pollutant.

4.4.1 Uniform Allocation
The uniform allocation method yields one limit per pollutant that will apply to all SIUs.

This allocation method requires that the MAIL for the pollutant be divided by the total flow from all SIUs, even those that do not discharge the pollutant. This method can be overly stringent because some IUs that do not discharge a pollutant will be given an allocation of the MAIL that they may not need. Equation 11 shows the method to calculate a local limit using the uniform allocation method.

City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Equation 11 – Uniform Allocation Calculation
Clim = MAIL / [(Qsiu) * 8.34]
Where:

Clim = Uniform concentration limit, mg/L
MAIL = Maximum allowable industrial loading, lb/day
Qsiu = Total flow rate from SIUs, MGD

8.34 = Unit conversion factor

4.4.2 IU Specific Allocation
There are two methods to divide the MAIL fo r each pollutant among only the SIUs that discharge that particular pollutant. Thes e methods develop SIU-specific discharge limits. Any SIU that dischar ges at or below the background level is given a background allocation.

The SIU Contributory Flow method is simila r to the Uniform Allo cation method except that the portion of the MAILs above the background level is divided by the flow rate from those SIUs discharging the pollutant above background. Equation 12 shows the SIU Contributory Flow Allocation calculation.

Equation 12 – SIU Contributory Flow Allocation Calculation Clim = [MAIL – Lback] / [(Qsiupol) * 8.34]
Where:

Clim = Uniform concentration limit, mg/L
MAIL = Maximum allowable industrial loading, lb/day
Lback = Background loading allocation for SIUs for which no contributory flow limit is being established for that pollutant, lb/day Qsiupol = Total flow rate from SIUs discharging the pollutant, MGD

8.34 = Unit conversion factor

4.4.3 The Mass Proportion Allocation
The mass proportion allocation method allocates the MAIL to each SIU in proportion to the SIU’s loading of that pollutant. To ca lculate the allowable loading for a SIU the portion of the MAIL above backg round is multiplied by the ra tio of the current loading from SIU X to the current total loading of a pol lutant from all SIUs. This calculation is shown in Equation 13.

Equation 14 shows the conversion of the mass allocation to a concentration.

City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Equation 13 – Mass Proportion Allocation Calculation
LallX = [LcurrX / LcurrT ] * [MAIL - Lback]
Where:

LallX = Allowable loading allocated to SIU X, lb/day
LcurrX = Current loading from SIU X, lb/day
MAIL = Maximum allowable industrial loading, lb/day
Lback = Background loading allocation for SIUs for which no contributory flow limit is being established for that pollutant, lb/day

Equation 14 – Mass Proportion Conversion to Concentration Limit ClimX = LallX / [(QX) * 8.34]
Where:

ClimX = Discharge limit for SIU X, mg/L
LallX = Allowable loading allocated to SIU X, lb/day
QX = Flow rate from SIU X, MGD

8.34 = Unit conversion factor

4.5 Uniform Allocation of Local Limits
Table 4-2 is a summary of the collected in formation and the proposed local limits based on the uniform allocation method. The details of the calculations in Table 4-2 are shown in Appendix F.

City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Table 4-2: Uniform Allocation of Local Limits
Maximum Safety Growth Nonindustrial Nonindustrial Nonindustrial Hauled Waste Hauled Waste Hauled Waste Allowable Local Basis Pollutant Allowable Factor Allowance Concentration Flow Loading Concentration Flow Loading Industrial Limit of Headworks (%) (%) (mg/l) (MGD) (lbs/day) (mg/l) (MGD) (lbs/day) Loading (mg/l) Limitation (MAHL - lbs/d) (SF) (GA) (Cdom) (Qdom) (Ldom) (Chw) (Qhw) (Lhw) (MAIL - lbs/day) (Cind) Arsenic 1.3568 10 10 0.0012 9.887966 0.0998 0.1587 0.011434 0.0151 0.9705 0.0510 Sludge Cadmium 0.0831 10 10 0.0001 9.887966 0.0058 0.0383 0.011434 0.0036 0.0571 0.0030 Water Quality Chromium 133.1733 10 10 0.0033 9.887966 0.2730 0.2521 0.011434 0.0240 106.2416 5.5857 Sludge Copper 7.9671 10 10 0.0320 9.887966 2.6389 4.2631 0.011434 0.4065 3.3282 0.1750 Water Quality Cyanide 1.7039 10 10 0.0009 9.887966 0.0709 0.0000 0.011434 0.0000 1.2922 0.0679 Water Quality Lead 0.8598 10 10 0.0014 9.887966 0.1130 0.5129 0.011434 0.0489 0.5259 0.0277 Water Quality Mercury 0.1713 10 10 0.0000 9.887966 0.0004 0.0118 0.011434 0.0011 0.1355 0.0071 Sludge Molybdenum 0.4931 10 10 0.0010 9.887966 0.0825 0.0805 0.011434 0.0077 0.3044 0.0160 Sludge Nickel 8.4145 10 10 0.0037 9.887966 0.3059 0.2572 0.011434 0.0245 6.4011 0.3365 Water Quality Selenium 0.8387 10 10 0.0006 9.887966 0.0495 0.0390 0.011434 0.0037 0.6178 0.0325 Sludge Silver 10.2811 10 10 0.0001 9.887966 0.0049 0.0035 0.011434 0.0003 8.2196 0.4322 Inhibition Zinc 33.8280 10 10 0.1678 9.887966 13.8386 28.7321 0.011434 2.7399 10.4839 0.5512 Sludge Ammonia 3452.9292 10 10 28.4300 9.887966 2344.4980 890.0000 0.011434 84.8700 332.9753 17.5064 Inhibition BOD 256354.5218 10 10 305.68 9.887966 25208.0957 - 0.011434 0.0000 179875.5217 9457.0764 Water Quality TSS 226555.1037 10 10 299.5 9.887966 24698.4581 - 0.011434 0.0000 156545.6248 8230.4914 Water Quality Boron 72.4485 10 10 0.24 9.887966 19.7918 0.0005 0.011434 0.0000 38.1670 2.0067 Water Quality Chloride 10767.6072 10 10 56.26 9.887966 4639.5167 650.0000 0.011434 61.9837 3912.5853 205.7068 Water Quality FOG 22573.6000 10 10 76.52 9.887966 6310.2705 1650.0000 0.011434 157.3433 11591.2662 609.4186 Water Quality

City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

4.6 IU Specific Allocation of Local Limits
Based on the uniform allocati on method, the proposed loca l limits for some pollutants are significantly lower than t he existing local limits. Thes e pollutants are: cadmium, copper, cyanide, lead, mercury, nickel, silver and zinc. The proposed local limits for these pollutants are also significantly lo wer than the concentrations seen in the discharge from the SIUs. Sampling data for the SIUs is in Appendix G.

The City currently imposes silver local lim its for Josten’s Printing and Publishing and Voltage Multipliers of 4.0 mg/L and 1.0 mg/L, respectively. The mass loading associated with these two SIUs was subtracted from the MAIL before it was distributed amongst the remaining silver contributing SIUs.

IU Specific Allocated local limits are meant to be applied to all industrial users regulated by the IPP. In order to provide additional protection, only 80% of the MAIL will be allocated via the IU Specific Allocation method. This wil l allow an additional amount of safety in the case where an industry that has not historically discharged a pollutant may discharge that pollutant above background concentrations.

Table 4-3 is a summary of the collected in formation and the proposed local limits based on the IU Specific Allocation me thod. Details of the IU Spec ific Allocation calculations are in Appendix H.

Table 4-3: IU Specific Allocation of Local Limits
Pollutant MAIL
(lb/day)
Uncontrolled
Discharge
Conc (mg/L)
Total IU flow
below
Uncontrolled
Conc (MGD)
L
back
(lb/day)
[Unc Conc x
IU flow below
Unc Conc]
Total IU flow
above
Uncontrolled
Conc (MGD)
IU
Specific
Allocation
Local
Limit
(mg/L)
Cadmium 0.0571 0.0001 2. 2166 0.00129 0.0643 0.08
Copper 3.3282 0.032 2.164 0.5775 0.1166 2.14
Cyanide 1.2922 0. 0009 2.2773 0.0163 0.0033 36.97
Lead 0.5259 0.0014 2.182 0.0249 0.0986 0.48
Mercury 0.1355 4.76x10 -6 1.9236 7.64x10 -5 0.357 0.04
Nickel 6.4011 0.0037 2. 171 0.067 0.1096 5.53
Silver 8.2196 0.0001 2.1763 0.0011 0.0563 12.40
Zinc 10.484 0.1678 2. 211 3.0944 0.0696 9.12
City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc

4.7 Comparison of Proposed and Existing Limits
Table 4-4 shows a comparison of the proposed local limits to the existing local limits and calculated local limits. Existing local limits for boron and pentachloropenol have been eliminated. Proposed local limits that are greater than the existing local limits are recommended to remain at the existing local limit value to prevent any lessening of local limits. Table 4-4 shows the recommended local limits based upon this evaluation.

Table 4-4: Comparison of Existing and Proposed Local Limits Pollutant Existing Local
Limit
Calculated Local
Limit
Allocation
Method
Proposed Local
Limit
Arsenic 0.05 mg/L 0.05 mg/L Uniform 0.05 mg/L
Boron 1.60 mg/L Not needed None
Cadmium 0.02 mg/L 0.08 mg/L IU Specific 0.02 mg/L
Chromium 3.44 mg/L 5.59 mg/L Uniform 3.44 mg/L
Copper 1.97 mg/L 2.14 mg/L IU Specific 1.97 mg/L
Cyanide 0.16 mg/L 36.97 mg/L IU Specific 0.16 mg/L
Lead 0.30 mg/L 0.48 mg/L IU Specific 0.30 mg/L
Mercury 0.02 mg/L 0.04 mg/L IU Specific 0.02 mg/L
Nickel 2.86 mg/L 5.53 mg/L IU Specific 2.86 mg/L
Silver1 0.76 mg/L 12.40 mg/L IU Specific 0.76 mg/L
Zinc 0.64 mg/L 9.12 mg/L IU Specific 0.64 mg/L
Pentachlorophenol 0.15 mg/L Not needed None
Oil & Grease 200 mg/L 609 mg/L Uniform 200 mg/L
BOD5 18,161 lb/day 89,538 lb/day 2 Not applicable 18,161 lb/day TSS 41,633 lb/day 41,633 lb/day 2 Not applicable 41,633 lb/day 1 Josten’s Printing and Voltage Multipliers retain silver limits of 4.0 mg/L and 1.0 mg/L, respectively.
2 Plant design capacity.

4.8 Protection of the Treatment Works, Collection System, and Workers

4.8.1 Fume Toxicity
There are certain pollut ants that can cause a fire or ex plosion, corrosive structural damage at the treatment plant, obstruction of fl ow, inhibition of biological activity due to heat, or discharges that cause the formation of toxic gases, vapors, or fumes.

City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Explosive and flammable pollutants discharged to a WWTF can threaten the integrity of the collection system and the health and safe ty of the workers. Under the right conditions, the accumulation of such po llutants in treatment works can produce explosions or fires. There are no POCs li sted in Table 2-5 that are listed in the EPA Guidance Manual as being potentially explosive.

The fume toxicity level of a pollutant di scharged to a WWTF indicates the likelihood that a WWTF worker will suffer an adverse health effect when the level is approached or exceeded. This level can be measured by t he time weighted average threshold limit value (TWA-TLV), which is the concentrati on to which a worker can be exposed for eight hours per day, 40 hours per week and not have any acute or chronic adverse health effects. Similarly, short-term exposure limits (STELs) are concentrations to which a worker should not be exposed for longer than 15 minutes or more than four times per day (with at least one hour between each exposure).

There were three POCs identif ied in Table 2-4 that have fume toxicity exposure limits that indicate they may create a toxicity ex posure issue for collection system workers.

The three POCs were chloroform, ethy lbenzene, and toluene. The fume toxicity discharge screening level can be calculat ed using Equation 15. The discharge screening level is the concentration in the treatment works above which a local limit may be necessary.

Equation 15 – Calculation of Discharge Screening Level
Clvl = Cvap / H
Where:

Clvl = Discharge screening level, mg/L
Cvap = Exposure limit at 1 atm and 25oC, mg/m3
H = Henry’s Law Constant, (mg/m3)/(mg/L)

Table 4-5: Fume Toxicity Discharge Screening Levels
Pollutant Exposure
limit (mg/m
3)
Henry’s Law
Constant
(mg/m
3)/(mg/L)
Discharge
Screening
Level (mg/L)
Maximum
Concentration
Sampled
(mg/L)
Chloroform 9.76 163.5 0.06 0.028
City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc Ethylbenzene 542.50 327.0 1.659 <0.0005
Toluene 565.50 272.5 2.075 0.0019
Based on the maximum concentrations sampl ed in the treatment works and the fume toxicity discharge screening levels, no local limits are needed for chloroform, ethylbenzene or toluene based upon the protection of the treatment works, collection system and workers.

4.8.2 Oil and Grease
Based on the uniform allocation of the oi l and grease maximum allowable industrial loading, the local limit woul d be 669 mg/L. This local limit is based upon protecting the WWTFs ability to meet the WDR oil and grease limitation.

However, by its very nature, grease will ad here to many types of surfaces with sewers especially vulnerable to grease build-up. The cool internal surfaces of sewers provide ideal locations on which thin layers of gr ease can build up. Over a period of time, clumps of grease will build up to the point t hat the sewer can be completely choked.

Grease also accumulates due to cooling and dilu tion of surfactants, that allows the grease to separate and collect on all sewer system surfaces, including wetwells at pump stations, where controls can become fouled and prevent pumps from operating properly.

Based on the residential (background loading) monitoring data, the average background oil and grease concentration is 76.5 mg/L. The average SIU concent ration for oil and grease is 133 mg/L. The avera ge oil and grease concentration into the WWTF is 57 mg/L.

The most commonly used local limit for oil & grease is 100 mg/L. The City currently has a limit of 200 mg/L. The 100 mg/L limit is not based upon any empirical evidence but rather on general correlations and an industry consensus that this level limits the build up of oil and grease in the collection system. The federal pretreatment regulations, 40 CFR 403.5(b)(6), prohibit “pet roleum oil, non-bi odegradable cutting oil, or products of mineral oil origin in amounts that will cause interference or pass through.” In most municipalities, oil and grease limits of 100 mg/L to 300 mg /L are protective of the collection system. Limits may need to vary depen ding on different fa ctors, such as the number of wet wells, type of sewers, slope of sewers, flow in sewers, maintenance of the sewers, and history of grease related clogs.

Based upon the concentrations of oil and greas e from residential and industrial sources and the history of grease, the current local limit of 200 mg/L is protective of the collection system and should remain.

4.9 Public Participation
The EPA General Pretreatment Regulati ons encourages public participation by requiring public notices or hear ings for local limits development. The City of Visalia must publish a notice (including a notice for a public hearing) in a newspaper of general City of Visalia
SECTION FOUR Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc circulation within the jurisd iction served by the WWTF. All comments regarding the proposed local limits as well as any reques t for a public hearing must be filed with the Approval Authority (the RWQCB) within 30 days. The Approv al Authority is required to account for all comments received when deciding whether to approve or deny the proposed local limits. The decis ion is then provided to the City and other interested parties, and published in the newspaper. All comments received are made available to the public for inspection and copying.

The City should notify the existi ng SIUs and other interested parties, individually, of the proposed limits and announce a publ ic comment period in the local newspaper. This public comment period can be open while the proposed limit s are submitted to the Approval Authority for initial review. During the comment period, the public may present technical challenges to the rationale for a particular local limit.

4.10 Implementation
Upon approval from the RWQCB, the approv ed limits need to be added to the existing sewer use ordinance. Once integrated in the sewer use ordinance, the approved local limits can be included into the permits issued to the SIUs.

City of Visalia
SECTION FIVE Local Discharge Limits Development

H:\(1) AGENDAS for Council - DO NOT REMOVE\2011\6-20-2011\Item 11q Attachment - Visalia Local Limits Report.doc 5 BIBLIOGRAPHY/REFERENCES
United States. Environmental Protection Agen cy. Local Limits Development Guidance.

Washington, D.C., July 2004.

APPENDIX A – WWTF Sampling Data

APPENDIX B – Bis (2-ethylhexyl) Phthalate Sampling Data

APPENDIX C – WWTF Biosolids Data

APPENDIX D – Residential Background Sampling Data

APPENDIX E – Septage Hauler Sampling Data

APPENDIX F – Local Limits Calculations (Uniform Allocation)