Attachment 6t - CPC Staff Report - May 21, 2026 — Riverside City Council, July 14, 2026

CALCULATIN GMAXWELLIVREQUIREMEN TS
The ty pe of property , soil permeability , rainfall intensityand local drainage ordinances determine the number and design of MaxWell Sy stems. For general applications draining retained stormwater, use one standardMaxWell IV per the instructions below for up to 3 acres of landscaped contributoryarea, and up to 1 acre of paved surface. For larger paved surfaces, subdivision drainage, nuisance water drainage, connecting pipes larger than 4"Øfrom catch basins or underground storage, or other demanding applications, refer to ourMaxWell® Plus Sy stem. For industrial drainage, including gasoline service stations, ourEnvibro® System maybe recommended. For additional considerations, please refer toDesign SuggestionsFor Retention AndDrainage Systemsor consult our Design Staff.

COMPLETIN GTHEMAXWELLIVDRAWIN G
To applytheMaxWell IVdrawing to y our specific project, simplyfill in the blue boxes per instructions below. For assistance, please consult our Design Staff.

ESTIMATED TOTALDEPTH
The Estimated Total Depth is the approximate depth required to achieve 10 continuous feet of penetration into permeable soils. Torrent utilizes specializedcrowd equipped drill rigs to penetrate difficult, cemented soils and to reach permeable materials at depths up to 180feet. Our extensive database of drilling logs and soils information is available for use as a reference. Please contact our Design Staff for site-specific information on y our project.

SETTLIN G CHAMBERDEPTH
On MaxWell IV Sy stems of over 30 feet overall depth and up to 0.25cfs design rate, the stand ardSettling Chamber Depth is18 feet.For sy stems exposed to greater contributory area than noted above, extreme service conditions, or that require higher design rates, chamber depths up to 25 feet are recommended.

OVERFLOWHEIGHT
The Overflow Height and Settling Chamber Depth determine the effectiveness of the settling process. The higher the overflowpipe, the deeper the chamber, the greaterthe settling capacity . For normal drainage applications, an overflowheight of 13feetis used with the standard settling chamber depth of 18 feet. Sites with higher design rates than noted above, heavydebris loading or unusual service conditions require greatersettling capacities

DRAIN AGEPIPE
This dimension also applies to thePureFlo® Debris Shield, theFloFast® Drainage Screen, and fittings. The size selected is based upon sy stemdesign rates, soil conditions, and the need for adequate venting. Choices are 6" , 8" , or 12"diameter. Refer to Design Suggestions forRetention and Drainage Sy stemsforrecommendations on which size best matches y ourapplication.

BOLTEDRIN G& GRATE
Standard models are quality cast iron and available to fit 24" Øor 30" Ømanhole openings. All units are bolted in two locations with wording Storm Water Only in raised letters. For other surface treatments, please referto Design Suggestions for Retention and Drainage Sy stems.

IN LETPIPEIN VERT
Pipes up to 4"in diameter from catch basins, underground storage, etc. maybe connected into the settling chamber. Inverts deeper than 5 feet will require additional settling chamber depth to maintain effective overflow height.
' "Ø
"Ø
"Ø
'
'
®

TORRENT RESOURCES (CA) INCORPORATED
phone 661~947~9836
CALic. 886759 A, C-42
www.TorrentResources.com
An evolution of McGuckin Drilling

TORRENT RESOURCES INCORPORATED
1509 East ElwoodStreet, PhoenixArizona 85040~1391
phone 602~268~0785 fax602~268~0820
N evad a702~366~1234
AZ Lic.ROC070465 A, ROC047067 B-4; ADWR363
CALic. 528080 A, C-42, HAZ ~ NV Lic. 0035350 A ~ NM Lic. 90504 GF04 Thereferenceddrawingandspecificat ionsareavailableonCADeit hert hroughourofficeorwebsit e.This det ail is copyright ed(2004)butmaybeusedasisinconst ruct ionplanswit houtfurt herrelease.Forinformat ion on productapplicat ion,individualprojectspecificat ionsorsit eevaluat ion,cont actourDesignSt affforno-charge assist anceinanyphaseofyourplanning.

1. ManholeCone - Modified Flat Bottom.

2. MoistureMembrane- 6 Mil. Plastic. Applies onlywhen
native material is usedfor backfill. Place membrane
securelyagainst eccentric cone and hole sidewall.

3. BoltedRing& Grate - Diameter as shown. Clean cast iron with wordingStormWaterOnly in raised letters.Bolted
in2locationsand secured to cone with mortar. Rim elevation ±0.02'of plans.

4. Grad edBasinorPaving(byOthers).

5. CompactedBaseMaterial - 1-Sack Slurryexcept in
landscaped installtions with no pipe connections.

6. PureFlo®DebrisShield- Rolled 16 ga. steel X24"length with vented anti-siphon and Internal .265"Max. SWO
flattened expanded steel screen X12"length. Fusion
bond edepox ycoated .

7. Pre-castLiner- 4000 PSI concrete 48"ID. X54"OD.Center inhole and align sectionstomax imizebearingsurface.

8. Min.6' Ø DrilledShaft.

9. SupportBracket- Formed 12Ga. steel.Fusionbond ed
epox ycoated .

10. OverflowPipe- Sch. 40PVC matedto drainagepipe at
base seal.

11. DrainagePipe- ADS highwaygrade with TRI-A coupler.

Suspendpipeduring backfill operations to prevent
buckling orbreakage. Diameter as noted.

12. BaseSeal - Geotextile or concrete slurry .

13. Rock- Washed, sized between 3/8"and 1-1/2"tobest
complementsoilcond itions.

14. FloFast® DrainageScreen- Sch. 40 PVC 0.120"slotted
well screenwith 32slots per row/ft.Diametervaries 120"
overall lengthwith TRI-B coupler.

15. Min.4'Ø Shaft- Drilled tomaintainpermeabilityof
drainage soils.

16. FabricSeal - U.V. resistantgeotextile -toberemoved
bycustomer at project completion.

17. Absorbent Hy drophobic Petrochemical Sponge.

Min. to 128 oz.capacity .

18. FreeboardDepthVaries with inlet pipe elevation. Increase settling chamberdepth as needed tomaintain all inlet
pipe elevations above overflow pipe inlet.

19. Optional Inlet Pipe(Maximum 4" , byOthers). Extend
moisture membrane and compacted base material or
1 sack slurrybackfill below pipe invert.

ITEMN UMBERS

MAXWELL
®

IVDRAIN AGESYSTEMDETAILAN DSPECIFICATION S
T he watermar k f or drainage solutions.®1/12
Manufacturedand Installedby

TORRENT RESOURCES
An evolutionofMcGuckin Drilling
www.torrentresources.com
ARIZONA 602/268-0785
NEVADA 702/366-1234
CALIFORNIA 661/947-9836
®Manufactured and Installedby

TORRENT RESOURCES
An evolution ofMcGuckinDrilling
www.torrentresources.com
ARIZONA 602/268-0785
NEVADA 702/366-1234
CALIFORNIA 661/947-9836
AZ Lic. ROC070465 A, ROC047067 B-4, ADWR 363
CA Lic. 528080, C-42, HAZ.

NV Lic. 0035350 A - NM Lic. 90504 GF04
U.S. Patent No. 4,923,330 -
TM
Trademark 1974, 1990, 2004
®

DRAINAGE MAINTENANCE
With over thirty years of experience to draw on, Torrent Resources records clearly show that utilizing regular
inspection and cleaning procedures can significantly
enhance the service-life and performance of the drainage systems it installs. Maintenance Data Sheets accompany all MaxWell and Envibro Systems at the time of completion
that provide operational information and instructions for inspection and service.

As a benefit to all MaxWell and Envibro owners, Torrent offers a full range of maintenance programs to protect the investment made in its drainage systems. With thorough
knowledge and experience to analyze the operational and structural aspects of our patented products, we can
effectively accomplish these basic, yet important services.

Torrent can provide Preventive Maintenance Programs that are tailored for your site including full service contracts.

These services would include a preliminary inspection of the settling chambers and internal components and an
assessment of the site drainage to insure that the system meets operational guidelines. A written report is provided at the completion of each inspection.

MaxWell system cleaning is accomplished with truck
mounted hydro-vactor equipment, utilizing water and air to dislodge and remove debris and sediment deposits. All
chambers, inlets, connecting piping and catch basins are cleaned with the contents evacuated and transported
off-site for disposal. Geotextile fabric base seals and hydrophobic petrochemical sponges are removed and
replaced in each chamber. Inlet grates and covers are then re-installed and re-secured with existing locking devices.

Envibro system cleaning utilizes similar maintenance
equipment. Servicing includes removal of debris from the trash basket under the collector grate inlet, hydro-
vactoring all chambers and cleaning of silt filters. All, inlets, connecting piping and catch basins are cleaned as well with the contents evacuated and transported off-site for disposal. Inspection of the Imbiber Beads® Drain Field assembly is also included in standard maintenance. All
hydrophobic absorbents blankets are replaced and inlet
grates and covers are re-installed and re-secured with
existing locking devices.

Under normal operation, Envibro cleaning is recommended annually or following heavy rainfalls and high loading of the system with foreign trash and debris. Should a spill or other discharge occur, complete service of the systems and replacement of activated Imbiber Beads® Drain Field
assembly is normally required.

Below is a list of our Drainage Maintenance services:

Preventative Maintenance
Service Contracts
Drywell Cleaning
Imbiber Beads® is a registered Trademark of Imbibitive Technologies Corporation
“Sun State Builders has had the privilege of
working with Torrent Resources for several
years. We find their work to be of excellent
quality and their customer service is
superior. We look forward to utilizing their
services in all of our projects in the future.”
Andrea Vallas
Assistant Project Manager
Sun State Builders
Torrent Resources - The watermark for drainage solutions. http://www.torrentresources.com/drainMaintenance.ht m
1 of 1 11/25/2009 4:42 P M

Corrugated Metal Pipe
Infiltration System
Solutions Guide

ENGINEERED SOLUTIONS
2 © 2015 Contech Engineered Solutions LLC
Stormwater Solutions from Contech
Selecting the Right Stormwater Solution Just Got Easier...

It’s simple to choose the right stormwater solution to achieve your goals with the Contech Stormwater Solutions Staircase. First, select the runoff reduction practices that are most appropriate for your site, paying particular attention to pretreatment needs. If the entire design storm cannot be retained, select a treatment best management practice (BMP) for the balance. Finally, select a detention system to address any outstanding downstream erosion.

Learn more about all of our stormwater
technologies at www.ContechES.com/urbangr een
Design Your own Detention or infiltration sYstemDYODS The Contech DYODS is an exclusive online design
tool to that allows users to quickly and easily design
their own detention or infiltration system. Just input
your required storage volume to calculate the
quantity of the material needed for your Contech

CMP , CON/SPAN
®, or ChamberMaxx® system.

To use the Design Your Own Detention
or Infiltration System tool, visit:
www.ContechES.com/dyods

3 Learn more at www.ContechES.com/ cmp-detention
The only sure way to eliminate stormwater pollution is to eliminate stormwater runoff. In recognition of this fact, Green Infrastructure and Low Impact Development based
stormwater management regulations prioritizing runoff
reduction have proliferated throughout the United States.

Where site conditions allow, infiltration is typically the most cost effective and reliable runoff reduction approach. In urban environments where there are competing demands
for land, subsurface infiltration can provide many of the benefits of landscape based systems but without requiring dedicated land area. Infiltration systems are commonly comprised of a pretreatment component designed to
remove sediment, trash, and oil, followed by plastic, metal or concrete storage units surrounded by permeable stone creating a high voids storage gallery. Infiltration systems are typically designed to support vehicular loading and to withstand lateral pressures from surrounding soil that allows the overlying land to be used for virtually any non-building application.

Subsurface Infiltration as a Stormwater Management Strategy LID benefits include runoff volume reduction, peak flow control, ground water recharge, and water quality improvement.

CMP infiltration is used at Pitzer College in Claremont, California.

Subsurface infiltration meets the objectives
of LID by reducing runoff with the added
benefit of saving land space in urban
environments.
4 CMP – the “Go To” Material for Subsurface Infiltration The purpose of the storage vessel is to hold stormwater runoff underground while allowing it to infiltrate the
surrounding soil. For the majority of applications, corrugated metal pipe (CMP) is the “go to” material for subsurface infiltration.
• A minimum of 75-year service life for most soil/water conditions.
• Various pipe coatings and materials are available to accommodate site-specific needs and extend service life:

Aluminized Steel Type 2 (ALT2), Galvanized, CORLIX
®
Aluminum, and Polymeric.
• Wide range of gages, corrugations, and shapes, in
diameters 12” – 144”.
• Pipe can be fully or partially perforated for infiltration, retention, or groundwater recharge applications.
• Custom access risers and manifolds provide direct
access for maintenance.
• Outlet control devices can be incorporated within the system, eliminating the need for a separate structure.
• Customizable - a variety of fittings allow CMP to match most layout configurations.
• May be designed for heavy loading and high maximum
cover.
• Contributes to LEED points.
• Available locally; quick turnaround time.
• The most economical installed solution.

A wide range of CMP diameters and coatings are available to meet site specific needs.

CMP can be laid out in configurations
not achievable with other materials.

With its low cost, a wide variety of diameters,
layout configurations, and materials, no other
material can match CMP’s flexibility and versatility.

5 Learn more at www.ContechES.com/ cmp-detention
Some engineers are hesitant to use corrugated metal pipe (CMP) for stormwater applications because they have read or heard about CMP being used in culverts that have corroded.

This shouldn’t be the case. Many decades ago, galvanized pipe was the coating of choice for culverts; that now has been replaced with Aluminized Type 2 (ALT2). The primary reason for culvert failure is the galvanized coating was not properly designed to withstand a high flow and abrasive environment, which wears the galvanized coating off the invert of the pipe.

The ALT2 is far more abrasive resistant for applications such as culverts and has a wider range for pH and resistivity.

Additionally, a detention/infiltration application is not an abrasive environment, so these concerns are further mitigated.

Finally, a properly designed infiltration system includes pretreatment and flow control, as well as a stone envelope which prevents interaction with native soils, further reducing the potential for abrasion and corrosion.
• A minimum of 75 year service life for most soil/water conditions and has a proven service life that exceed 100 years with proper specification that meets all AASHTO and ASTM pipe specifications.
• CMP infiltration systems can be designed to meet HS-20 or greater load requirements with proper depths of cover. • With no abrasion and low flows, coatings remain intact and protect against corrosion inside the pipe that holds stormwater runoff.
• Protective pipe coatings and materials such as ALT2, Galvanized, Polymeric, and CORLIX
® Aluminum are
matched to the pH and resistivity of the surrounding soil. • CMP infiltration systems are surrounded by clean crushed rock to provide increased storage capacity. The entire
system is wrapped with fabric on the sides and top to
prevent the soils from having contact with CMP . Thus,
corrosive soils do not come into contact with the pipe.

Addressing the Question of Longevity
CMP has a proven service life
CMP infiltration systems have a proven
service life that exceeds 100-years with
proper specification that meets all AASHTO
and ASTM pipe specifications.

Learn more about the durability of steel through
the recent NCSPA ALT2 Study - www.ncspa.or g
6 Maximizing Vertical Space: Every Inch Counts
One of the most overlooked advantages of CMP is its
ability to maximize vertical storage space.

Increasing the depth of a CMP infiltration system
allows for more water storage in the same footprint.

For example, doubling the diameter of pipe yields
four times as much storage volume in the pipe. This
provides a significant cost savings per cubic foot of
storage. In addition, more vertical storage space
means a smaller footprint, less excavation, and lower
project costs.
2x the diameter - 4x the stor age
Diameter
(inches)
Volume
(ft3/ft) Min. Cover Height Diameter
(inches)
Volume
(ft3/ft) Min. Cover Height
12 .78 12” 78 33.1 12”
15 1.22 12” 84 38.4 12”
18 1.76 12” 90 44.1 12”
21 2.40 12” 96 50.2 12”
24 3.14 12” 102 56.7 18”
30 4.9 12” 108 63.6 18”
36 7.0 12” 114 70.8 18”
42 9.6 12” 120 78.5 18”
48 12.5 12” 126 86.5 18”
54 15.9 12” 132 95.0 18”
60 19.6 12” 138 103.8 18”
66 23.7 12” 144 113.1 18”
72 28.2 12”
Round Pipe – CMP 6-in to 144-in
Sizing
96” diameter - 50.2 ft³/ft
48” diameter - 12.5 ft³/ft
Contech’s Corrugated Metal Pipe Detention
systems maximize vertical storage space.

7 Learn more at www.ContechES.com/ cmp-detention
7 Infiltration systems have multiple components, and one of the most important is pretreatment. The purpose of a pretreatment device is to prolong the life of the infiltration system by removing debris and sediment that can collect on the invert and within the stone backfill voids. Pretreatment will maintain the efficiency of an infiltration system as well as extend the life cycle, therefore preventing a premature replacement. Pretreatment also offers these additional
benefits:
• Easier to clean and maintain compared to the
infiltration system itself.
• Cost savings due to the extended service life of the system.
• Removing trash and debris protects downstream outlet control structures from clogging.

Pretreatment Design Considerations
When choosing a pretreatment system, it is important to consider the following:
• Downstream outlet control structures may require
protection from a pretreatment device that screens
trash and debris.
• Pretreatment system selection depends on pollutant
targets. Trash, debris, and larger particles can be
removed with hydrodynamic separators. Removing
high percentages of fine particles and associated heavy metals and nutrients requires filtration.
• Reduced long term maintenance or replacement cost
of the infiltration system can help justify pretreatment construction costs.
• Inlet and pipe layout will influence the number and
type of pretreatment systems used. A combination of
different systems may be appropriate for the various
inlet locations and flows.

The Need for Effective Pretreatment
Pretreatment systems that are easy to maintain
and do not rely on the use of geotextile fabric are
preferred.
8 Contech offers a number of pretreatment options, all of which will extend the life of subsurface infiltration systems and improve water quality. The type of system chosen will depend on a number of factors including footprint, soil conditions, local regulations, and the desired level of pretreatment.

Pretreatment Options
CDS provides direct access to cleaning, and the
built-in high flow bypass weir eliminates the need
for a separate bypass structure.

Hydrodynamic Separation
Hydrodynamic Separation (HDS) provides a basic level of pretreatment by capturing and retaining trash and debris, sediment, and oil from stormwater runoff.

CDS®
The CDS uses a combination of swirl concentration and indirect screening and is the only non-blocking screening technology available in an HDS system.

Filtration
Filtration provides a higher level of pretreatment and improved water quality by removing trash and debris, oil, fine solids, and dissolved pollutants such as metals, hydrocarbons, and nutrients.

Filterra® Bioretention System
Filterra is an engineered bioretention system that has been optimized for high volume/flow treatment and high pollutant removal.

The Stormwater Management StormFilter®
The StormFilter system is comprised of a structure that houses rechargeable, media-filled cartridges. The media can be customized to target site-specific pollutants.

Jellyfish® Filter
The Jellyfish filter uses membrane filtration in a compact footprint to remove a high level and a wide variety of stormwater pollutants such as fine particulates, oil, trash and debris, metals, and nutrients. 9 Learn more at www.ContechES.com/ cmp-detention
There may be instances where alternative materials are
needed for subsurface infiltration due to site specific needs.

Plastic Chambers
Plastic chambers are best suited to shallow depth
applications; minimum cover is 18 inches, and maximum
cover is 96 inches. Some benefits of chambers are:
• Chambers may be beneficial for sites with limited vertical storage.
• Lightweight and installed by hand.
• Heavy equipment is not required to set units into place. • Centralized stocking locations for short lead times.

Concrete Structures/Vaults
Some concrete structures and vaults are best suited for high loading applications such as railroads or airports. Concrete units are also ideal in corrosive environments or areas with high salinity. Some benefits of concrete structures are:
• Wide range of spans and heights.
• Greater underground infiltration storage in a smaller footprint.
• Ample and easy maintenance access.
• Fast installation.

Alternative Materials for Subsurface Infiltration

10 Project Profiles: CMP Infiltration Systems in Action City Center Regional Stormwater Facility
Mountlake Terrace, Washington
• The city of Mountlake Terrace, Washington needed a new stormwater retention facility to provide stormwater treatment and downstream flood control.
• There was limited footprint for 80,000 CF of runoff, and the system was required to be very deep, with about 15’ of cover.
• Engineers designed a system consisting of a CDS
pretreatment system in front of 800 linear feet of 120” diameter, perforated, aluminized type 2 CMP that allows the runoff to slowly infiltrate the surrounding soil.
• Perforated CMP was selected for its ability to accommodate the deep bury, the relatively small footprint, and cost effectiveness.

Creative Office Space
El Segundo, California
• A stormwater infiltration solution was needed for a new group of office buildings.
• The owner wanted to maximize the use of the parking
area in the urban setting.
• The site had a tight footprint and multiple utility
constraints, requiring the design of five separate systems. • A total of 860 LF of perforated CMP was installed
providing of 25,265 CF of storage.
• Perforated CMP was selected for its design flexibility, cost effectiveness, and ease of installation.

Edie and Lew Wasserman Building, UCLA
Westwood, California
• The new six-story, 100,000 square foot Edie and Lew
Wasserman Building was built on a very dense site that
needed to meet sustainability requirements.
• The design needed to maximize infiltration volume, match existing inverts, and work around existing utilities.
• The stormwater management systems included a CDS
pretreatment system and a CMP infiltration system using 57’ of 72” perforated CMP .
• Perforated CMP was selected to avoid utilities, minimize excavation, meet the City of LA LID requirements, contribute to the building’s LEED certification, and to provide space for the buildings “outdoor room” and gardens.
11 Learn more at www.ContechES.com/ cmp-detention
The Right Partner Can Make All the Difference
Regardless of your project’s objectives and constraints, our team of stormwater design engineers, regulatory managers, and local stormwater consultants are here to provide you with expert advice and assistance. If your goal is to eliminate or detain runoff, you can rely on Contech for a wide range of subsurface infiltration, detention, and rainwater harvesting solutions. If treatment is needed, our landscape-based biofiltration or subsurface filtration designs can fit into virtually any site and can be tailored to address specific pollutants.

At every stage of your project, count on Contech to provide engineering services including:
• Regulatory guidance and permitting assistance
• Preliminary standard details and/or site specific final CAD drawings and specifications • Low Impact Development design assistance
• Engineering calculations for hydraulics/hydrology, rainwater harvesting, and detention/retention • Online “Design Your Own” tools
• Review of preliminary site design, feasibility screening, and layout assistance • Value engineering – cost estimates and options analysis • Pre-construction support, project scheduling, and contractor coordination • Installation and construction support
• Maintenance support:
» Guidance manuals
» Demonstrations
» Qualified contractor identification
The result: an efficient design process, the right product, greater land space savings, and faster permitting. The entire Contech stormwater team welcomes the opportunity to work with you on your stormwater projects.

To get started, please visit www.conteches.com/localresources or call us at 800-338-1122.

We print our brochures entirely on Forest
Stewardship Council certified paper. FSC
certification ensures that the paper in
our brochures contain fiber from well-
managed and responsibly harvested
forests that meet strict environmental and
socioeconomic standards.

FSC
CMP Infiltration Bro (5M as of 1/15) PDF 10/15

NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS AN EXPRESSED WARRANTY

OR AN IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. SEE THE CONTECH STANDARD CONDITION OF SALES (VIEWABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION.

ENGINEERED SOLUTIONS
©2015 Contech Engineered Solutions LLC
800-338-1122 | www.ContechES.com
All Rights Reserved. Printed in the USA.

Get Social With Us!

ENGINEERED SOLUTIONS
Pipe Solutions
Meeting project needs for durability,
hydraulics, corrosion resistance,
and stiffness
• Corrugated Metal Pipe (CMP)
• Steel Reinforced Polyethylene (SRPE)
• High Density Polyethylene (HDPE)
• Polyvinyl Chloride (PVC)
Treatment Solutions
Helping to satisfy stormwater
management requirements on
land development projects
• Stormwater Treatment
• Detention/Infiltration
• Rainwater Harvesting
• Biofiltration/Bioretention
Structures Solutions
Providing innovative options and
support for crossings, culverts,
and bridges
• Plate, Precast & Truss bridges
• Hard Armor
• Retaining Walls
• Tunnel Liner Plate

COMPLETE SITE SOLUTIONS
Links to Stormwater Tools:

To use the Land Value Calculator, visit:
www.ContechES.com/lvc
(Look under the Stormwater Management section to download the Land Value Calculator) To use the Design Your Own Detention System tool, visit:
www.ContechES.com/dyods
To use the Design Your Own Hydrodynamic Separator tool, visit: www.ContechES.com/
dyohds
To use the Rainwater Harvesting Runoff Reduction Calculator tool, visit: www.ContechES.com/
rwh - calculator
To use the LID Site Planner , visit:
www.ContechES.com/LIDsiteplanner
Dig Deeper
Find all the information you need at www.ContechES.com, including field and laboratory test results, approvals, brochures, design guides, standard details, and
specifications within the product section of our site.

Connect with Us
We're here to make your job easier – and that includes
being able to get in touch with us when you need to.

Go to www.ContechES.com/ConnectWithContech.

While you’re there, be sure to check out our upcoming
seminar schedule or request an in-house technical
presentation.

Start a Project
If you are ready to begin a project, contact your local representative to get started. Or you can check out our design toolbox for all our online resources at
www.ContechES.com/
designtoolbox.

STATEMENT OF QUALIFICATIONS

AQUA-SWIRL® STORMWATER TREATMENT SYSTEM

January 2017

AquaShieldTM, Inc.
2733 Kanasita Drive
Suite 111
Chattanooga, Tennessee 37343
(888) 344-9044
Fax (423) 826-2112
www.aquashieldinc.com

Aqua-Swirl® Statement of Qualifications

Table of Contents
Page

1.0 Overview 1

1.1 Mode of Operation 1

1.2 General Equipment Design 2

1.3 Range of Operating Conditions 3

1.4 Contaminants to be Treated 3

1.5 Inspection and Maintenance 4

2.0 Construction Materials 5

3.0 Use Applications 5

4.0 Performance Testing 5

4.1 Laboratory Testing 6

4.2 Field Testing 6

5.0 Regulatory Approvals 7

5.1 States and Provinces 8

5.2 State Departments of Transportation 9

5.3 Regional Planning Authorities 9

5.4 Counties 9

5.5 Municipalities 10

6.0 Limited Warranty 10

AQUA-SWIRL® STATEMENT OF QUALIFICATIONS

1.0 OVERVIEW

1.1 Mode of Operation

The Aqua-Swirl® Stormwater Treatment System (Aqua-Swirl®) is a custom engineered, post-construction flow-through structure designed to remove sediment, floating debris, trash and free-floating oil by utilizing hydrodynamic vortex-enhanced separation (Figure 1). The United States patent, “Drainwater Treatment System for Use in a Horizontal Passageway,” U.S. Patent No. 6,190,545 currently applies to the Aqua-Swirl®.

Figure 1. Diagram of Aqua-Swirl® Stormwater Treatment System showing the circular flow of water through the system which encourages settling of sediment and retention of floatable materials.

Aqua-Swirl® technology is a rapid or high flow rate device that has no moving parts and operates on gravity flow or movement of the stormwater runoff entering the structure. Operation begins when stormwater enters the Aqua-Swirl® by means of its tangential inlet pipe thereby inducing a circular (swirl or vortex) flow pattern. The diameter of the swirl chamber represents the effective treatment area of the device. Both sediment capture and sediment storage is accomplished within the swirl chamber. A combination of gravitational and hydrodynamic drag forces results in solids dropping out of the flow and migrating to the center of the swirl chamber where velocities are the lowest. Flow circulates downward where water exits the swirl chamber by flowing underneath and upward behind the arched inner baffle.

The top of the baffle is sealed across the treatment channel to eliminate floatable pollutants from escaping the swirl chamber. A vent pipe is extended up the riser to expose the backside of the baffle to atmospheric conditions, thus preventing a siphon from forming at the bottom of the baffle. Sediment is stored at the base of the swirl chamber while floatables remain captured with the treatment area.

Aqua-Swirl® Statement of Qualifications January 2017

2 © AquaShieldTM, Inc. 2017. All rights revserved.

1.2 General Equipment Design

A unique quality of the Aqua-Swirl® is its modular design which allows for faster and simpler installation on new construction or retrofit projects for existing storm drainage structures. The Aqua-Swirl® can operate in either an offline or online configuration. Offline designs rely on the use of a separate external bypass structures. The diversion structure directs only the designed water quality treatment flow (WQf) to the unit whereby flows in excess of the WQf bypass the Aqua-Swirl®. Online Aqua-Swirl® systems utilize an internal bypass design (models designated as “BYP”) to allow for the conveyance of both the WQf and the bypass flow volumes. Aqua-Swirl® systems provide for equal invert elevations for both the inlet and outlet pipe stubouts. No external driving head is needed for operation other than that needed to convey flow according to the site design.

The diameter of the swirl chamber’s treatment area varies from 2.5 to 13 feet depending on model size necessary to treat the WQf. Table 1 summarizes the available Aqua-Swirl® models, swirl chamber inner diameters, and oil/debris and sediment storage capacities.

Table 1. Aqua-Swirl® Models and Storage Capacities

Aqua-
Swirl®
Model
Swirl Chamber
Inner
Diameter
Water Quality
Treatment Flow
Rates
Oil/Debris
Storage Capacity
Sediment Storage
Capacity
(ft) (cfs) (gal) (ft3)
AS-2 2.5 1.1 37 10
AS-3 3.3 1.8 110 20
AS-4 4.3 3.2 190 32
AS-5 5.0 4.4 270 45
AS-6 6.0 6.3 390 65
AS-7 7.0 8.6 540 90
AS-8 8.0 11.2 710 115
AS-9 9.0 14.2 910 145
AS-10 10.0 17.5 1,130 180
AS-11 11.0 21.2 1,422 222
AS-12 12.0 25.2 1,698 270
AS-13 13.0 29.6 1,986 310
AS-XX Custom*
* Custom designs to meet site-specific criteria, can include multiple (twin) units for increased flow and materials storage capacity.

The Aqua-Swirl® is also designed so that it can easily be used for retrofit applications. When the invert of the inlet and outlet pipe of the Aqua-Swirl® is positioned at the same elevation the unit can easily be connected directly to the existing storm conveyance drainage system.

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3 © AquaShieldTM, Inc. 2017. All rights revserved.

Shop drawings and any other pertinent design drawings are provided on a site-specific basis. Additional information on custom designs and detail drawings can be provided on request for each of the construction materials available for the Aqua-Swirl® (see Section 2.0 construction materials). Given that Aqua-Swirl® systems can be custom designed, a number of offline configurations can be utilized.

AquaShieldTM can assist with facility layouts to minimize an Aqua-Swirl® footprint.

The Aqua-Swirl® has been designed and fabricated as a modular unit with no moving parts or on-site assembly required. Since the system is fabricated from high performance, lightweight and durable construction materials, the device can be installed without the use of a crane. Lifting supports are provided to allow easy offloading and installation with a backhoe or trackhoe. In addition, manufactured stubouts for the inlet and outlet piping are provided which allows the installer to simply attach the Aqua- Swirl® directly to the main conveyance storm pipe with Fernco™ or equivalent couplings. Pick weights are available on request.

All Aqua-Swirl® systems are supplied with octagonal base plates which typically extend a minimum of six inches beyond the outside diameter of the swirl chamber. The function of the base plate extension is to provide additional surface area to counter any buoyant force exerted on the system. The forces created on the base plate by the weight of the surrounding fill material offsets the buoyant force generated within the system. If needed, concrete can be poured directly onto the base plate to provide additional resistive force.

AquaShieldTM routinely performs buoyancy calculations for all system installations.

1.3 Range of Operating Conditions

Aqua-Swirl® systems have been designed to provide water quality treatment at a range of flow rates.

AquaShieldTM actively assists design engineers to properly size a system to meet site-specific water quality design storm. It is important to consider that when two identical Aqua-Swirl® units are installed in parallel the operating range can double from that of a single unit such that exceptionally large flow rates can be effectively treated.

1.4 Contaminants to be Treated

The primary waterborne contaminants of concern to be treated by the Aqua-Swirl® include:

 Suspended Sediment (commonly referred to as Total Suspended Solids, TSS)  Trash/Debris
 Free-floating oil

The quantities of the COCs to be treated are based on site-specific pollutant loading factors. While the Aqua-Swirl® is not specifically designed to function in lieu of an oil-water separator, the device still provides treatment against free floating oil when conditions allow.

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4 © AquaShieldTM, Inc. 2017. All rights revserved.

1.5 Inspection and Maintenance

A comprehensive Aqua-Swirl® Inspection and Maintenance Manual is provided for each site delivery for end users to understand system operations and track and document system inspection and maintenance cycles. AquaShieldTM recommends that periodic Aqua-Swirl® system inspections be performed to determine whether the disposal of captured material is needed to ensure proper operation of the treatment system. It is important to keep in mind that all stormwater control measures (SCMs), including manufactured treatment devices (MTDs), require some degree of maintenance. Maintenance cycles are ultimately dependent on site-specific pollutant loading conditions.

Upon installation and during construction, AquaShieldTM recommends that an Aqua-Swirl® treatment system be inspected every three months and the system be cleaned as needed. A typical maintenance event for the cleaning of the swirl chamber can be accomplished with a vacuum truck without the need to enter the chamber. The Aqua-Swirl® should be inspected and cleaned at the end of construction regardless of whether it has reached its capacity for sediment or oil storage. During the first year post-construction, the Aqua-Swirl® should again be inspected every three months and cleaned as needed. AquaShieldTM recommends that the system be inspected and cleaned once annually regardless of whether it has reached its sediment or floatable pollutant storage capacity. For the second and subsequent years post- construction, the Aqua-Swirl® can be inspected and cleaned once annually if the system did not reach full sediment or floatable pollutant capacity in the first year post-construction. If the Aqua-Swirl® reached full sediment or floatable pollutant capacity in less than 12 months in the first year post-construction, the system should be inspected once every six months and cleaned as needed. AquaShieldTM further recommends that all external bypass structures (divergent and convergent) should be inspected whenever an inspection and maintenance event is performed. These structures can adversely affect performance and functionality if left unchecked.

Essential elements of a swirl chamber inspection include observing floating materials and measuring the accumulated sediment at the base of the swirl chamber. These two activities can be performed at the ground surface (for a typical subsurface installation) and there is no need to enter the device. Provided that there are no significant access restrictions to the facility, it is considered that a system inspection should not exceed one half hour. A typical maintenance event includes the vacuuming and disposal of floatable pollutants and sediment from the swirl concentrator. Cleaning of the swirl chamber is often accomplished by use of a vacuum truck. It is estimated that the on-site activities for maintenance should not exceed one hour and can be performed by a one or two man crew. AquaShieldTM recommends that if entry to the swirl chamber is necessary for any reason, then confined space entry techniques should be followed.

Proper health and safety protocols should be followed during all inspection and maintenance events.

AquaShieldTM recommends that all materials removed during the maintenance process be handled and disposed in accordance with all applicable federal, state and local guidelines. Depending on the influent pollutant characteristics of the system drainage area, it may be appropriate to perform Toxicity Characteristics Leaching Procedure (TCLP) analyses on representative samples of the removed material to ensure that the handling and disposition of materials complies with all applicable environmental regulations.

Aqua-Swirl® Statement of Qualifications January 2017

5 © AquaShieldTM, Inc. 2017. All rights revserved.

2.0 CONSTRUCTION MATERIALS

The Aqua-Swirl® is available using construction materials of either High Density Polyethylene (HDPE) or Polymer Coated Steel (PCS). Unique site conditions may require deviations to standard installation specifications. It is recommended that AquaShieldTM be contacted prior to extraordinary installations to determine the extent to which any deviation, if possible, can be made to ensure that the integrity, functionality and product warranty of the device is maintained. Both HDPE and PCS provide high structural integrity for both long term durability and traffic loading conditions. Material specifications can be provided on request.

3.0 USE APPLICATIONS

Aqua-Swirl® technology can be applied to a wide variety of land uses and facilities. Common system applications include, but are not limited to, the following types of settings:

 Retail/Commercial Developments
 New and Existing Industrial Facilities
 Highway Construction
 Transportation facilities
 Watershed Protection
 Redevelopment/Retrofit Sites
 Government Facilities
 Military Installations, Bases and Berthing Wharfs
 Vehicle and Equipment Wash Rack Areas
 Fueling Centers and Convenience Stores
 Fast Food Restaurants
 Office Complexes
 Religious Centers
 Educational Facilities
 Residential Developments (single and multi-family)
 Coastal Zone Management Communities
 Drinking Water Well-head Protection Areas

Thousands of Aqua-Swirl® systems have been installed throughout the United States including the Commonwealth of Puerto Rico and the Territory of Guam. Aqua-Swirl® systems are also installed in Brazil, Canada, Hong Kong, India, the Middle East, Russia, South Korea and United Kingdom. Climatic conditions for Aqua-Swirl® installations range anywhere from sub-arctic (e.g., central Alaska) to sub- tropical locales. Information concerning domestic and international projects can be provided on request.

4.0 PERFORMANCE TESTING

The Aqua-Swirl® has completed comprehensive, independent full scale model testing in both laboratory and field settings. Summaries of both testing programs are provided in the following two sections.

Aqua-Swirl® Statement of Qualifications January 2017

6 © AquaShieldTM, Inc. 2017. All rights revserved.

4.1 Laboratory Testing

Independent performance testing of an Aqua-Swirl® Model AS-3 was conducted by the Department of Civil and Environmental Engineering at Tennessee Tech University (TTU), Cookeville and is described in the findings report, Laboratory Evaluation of TSS Removal Efficiency for Aqua-Swirl® Concentrator Stormwater Treatment System. The test parameters included loading rates, sediment concentrations, specific gravity, head loss, and particle size distribution. The test sediment was OK-110 manufactured by U.S. Silica, having a specific gravity of 2.65. The test material has a particle size range of approximately 50 to 150 microns (µm), representing the finest fraction of sand particulate. The test sediment manufacturer reports a median (d50) particle size of 110 µm. However, other independent laboratory- specific testing programs performed in association with Aqua-Swirl® product development actually demonstrated a d50 of 90 to 95 µm. Note that OK-110 is no longer manufactured due to the manufacturer’s inability to consistently meet the product specification.

Total suspended solids (TSS) concentrations were determined by the Suspended Sediment Concentration (SSC) analytical method consistent with ASTM D3977. The SSC method differs from the commonly cited TSS analytical method, EPA 2540D (formerly EPA 160.2) such that the SSC analysis is a whole sample TSS procedure. The analytical results of influent and effluent sample pair concentrations were used to calculate SSC removal efficiencies for each run at the target loading rates and concentrations.

This study concluded that Aqua-Swirl® achieves an SSC removal efficiency of 91% on a net annual basis.

The results of this laboratory testing program have been independently verified by the New Jersey Corporation for Advanced Technology (NJCAT). The Washington State Department of Ecology has also assigned the General Use Level Designation (GULD) for Pretreatment (TSS) for the Aqua-Swirl®.

4.2 Field Testing

An Aqua-Swirl® Model AS-5 completed a 27 month independent field testing program in accordance with the Technology Acceptance Reciprocity Partnership (TARP) Tier II Field Testing Protocol. A total of 18 storms and 15.16 inches of rain were sampled between March 2009 and June 2011, demonstrating that the Aqua-Swirl® achieved 86% and 87% TSS and SSC removal efficiency, respectively. AECOM of Philadelphia, Pennsylvania served as the independent field testing organization. The test site is an asphalt covered parking lot with landscaped areas at the urban retail center in Silver Spring, Maryland (metro Washington D.C.). All samples were collected using ISCO autosamplers positioned at the influent and effluent pipe connections. ISCO area-velocity modules were used to gauge influent and effluent flow conditions. Suspended sediment analyses were performed by both the TSS and SSC Methods as cited above. Particle size distribution (PSD) was determined by serial filtration. Average influent PSD data indicates that 86% of the particulate is <125 µm and 72% of the particulate is silt (1.5 to 63 µm). The test site particulate is classified as a clay loam textured sediment. The target NJDEP PSD is to exhibit a particulate range of 1.0 to 1,000 µm and a d50 of 67 µm. Figure 1 illustrates the influent PSD curve for the AS-5 and includes the NJDEP PSD standard. All field test analyses were performed by Test America, Inc. of Burlington, Vermont, a NELAP and New Jersey certified facility.

Aqua-Swirl® Statement of Qualifications January 2017

7 © AquaShieldTM, Inc. 2017. All rights revserved.

Figure 2. Particle size distribution for AS-5 Field test versus NJDEP laboratory test sediment particulate distribution.

Table 2 summarizes TSS and SSC removal efficiencies, storm durations, storm sizes, peak intensities, peak loading rates and percentage TVSS of TSS. Cumulative average sediment removal efficiencies for TSS and SSC are 86 and 87%, respectively. Cumulative average influent TSS and SSC concentrations are 132 and 145 mg/L, respectively. Storm sizes range from 0.11 to 4.4 inches with storm intensities ranging from 0.15 to 5.49 in/hr. Influent loading rates range from 1.9 to 35.4 gpm/ft2.

The AS-5 field testing results have also been independently verified by NJCAT to achieve 86% TSS removal on an annual basis, consistent with the laboratory findings. The Washington State Department of Ecology subsequently issued Conditional Use Level Designation (CULD) for the Aqua-Swirl® based on the results of the AS-5 field test.

5.0 REGULATORY APPROVALS

The approval lists included herein are not intended to represent all Aqua-Swirl® approvals or installation locations. Instead, the listings represent regulatory agencies that have some recognized measure of technology review in association with their local approval process for manufactured stormwater treatment devices (MTDs). Given that there are a number of scenarios that can be followed in order to gain a regulatory approval, the lists included below provide a high level of credibility toward the approval of the Aqua-Swirl® in a variety of regional and regulatory diverse settings. Additional information can be provided regarding regulatory approvals and installation locales.

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8 © AquaShieldTM, Inc. 2017. All rights revserved.

Table 2. Summary of Sediment Removal Efficiency and Storm Characteristics

#
Sample
Date
TSS
RE
(%)
SSC
RE
(%)
Storm
Duration
(hr:min)
Storm
Size
(in)
Peak
Storm
Intensity
(in/hr)
Peak
Loading
Rate
(gpm/ft2)
%
TVSS
of TSS
1 3/14/2009 98.3 99.3 0:30 0.11 0.26 4.1 NA
2 4/1/2009 86.8 82.7 0:50 0.18 0.46 8.1 NA
3 4/6/2009 82.5 85.5 2:00 0.15 0.26 4.8 NA
4 12/25-26/2009 99.0 99.5 11:45 0.56 0.38 4.8 NA
5 1/17/2010 94.8 96.3 4:48 0.59 0.42 10.4 NA
6 7/25/2010 94.1 96.5 0:46 0.55 1.21 16.9 38.8
7 8/12/2010 63.9 68.0 3:00 1.82 5.49 30.9 22.3
8 9/12/2010 96.5 96.6 3:45 0.61 0.49 13.1 31.0
9 9/29-30/2010 59.9 57.4 12:05 4.40 2.56 35.4 20.9
10 12/1/2010 89.1 86.9 6:20 0.71 1.82 4.1 16.7
11 12/11/2010 96.1 97.7 3:40 0.72 0.58 2.3 29.2
12 2/25/2011 73.0 72.8 2:15 0.29 0.25 4.1 29.0
13 3/6/2011 86.1 92.5 4:50 1.42 0.46 11.0 25.4
14 3/15-16/2011 88.1 91.7 5:06 0.42 0.35 1.9 24.4
15 4/8/2011 94.1 95.8 3:55 0.52 0.15 3.4 25.2
16 4/28/2011 80.4 82.0 2:19 0.23 0.23 12.5 71.4
17 5/14/2011 90.6 90.3 3:05 0.85 0.47 5.7 48.9
18 6/16/2011 74.3 82.7 3:20 1.03 0.91 13.1 48.9
Average 86.0 87.3 0.84 0.93 10.4 33.2
Total 15.16

5.1 States and Provinces

The following states and Ontario are recognized to issue use level designation for MTDs. Both NJDEP and Washington State administer the most widely recognized stormwater management programs throughout the U.S.

State / Province Agency Aqua-Swirl® Approval Status
New Jersey Department of Environmental Protection Field Test Certification Laboratory Test Certification
Washington Department of Ecology

General Use Level Designation for
Pretreatment (TSS)
Conditional Use Level Designation for
Basic (TSS) Treatment
Maryland Department of the Environment Approved
Virginia Department of Environmental Quality Approved (Total Phosphorus 20%) Wisconsin Department of Commerce. Approved
Ontario Ministry of the Environment Certificate of Technology Assessment

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9 © AquaShieldTM, Inc. 2017. All rights revserved.

5.2 State Departments of Transportation

Several states utilize their respective Departments of Transportation as a regulatory agency to administer the MTD approval process. These approvals can include use level designations specific to highway projects and can extend to most other installation applications for which MTD technologies can be utilized. It should also be kept in mind that a number of local jurisdictions also rely on their state’s DOT for MTD approvals. The table below lists state DOTs that have approved the Aqua-Swirl®.

State DOT Aqua-Swirl® Designation
California Approved
Michigan Approved
New Jersey Approved
North Carolina Provisional Use
Ohio Qualified Products List
Rhode Island Approved
Texas Approved
Utah Approved

5.3 Regional Planning Authorities / Water Use Districts

The Aqua-Swirl® maintains several approvals at the regional planning authority or water use district levels such that municipalities within those jurisdictions typically adopt these MTD approvals. Examples of such jurisdictional approvals for which the Aqua-Swirl® are cited below.

Jurisdiction Example Municipality(s)
Northwest Florida Water Mgmt. District Tallahassee
Nashville, TN Metro Water Services Nashville, Brentwood, Franklin Puerto Rico Electric Power Authority Island
St. Louis, MO Metro Sewer District St. Louis and surrounding municipalities, Missouri Tahoe Regional Planning Agency Lake Tahoe Basin, Nevada and California

5.4 Counties

Aqua-Swirl® approvals have also been issued through several counties that administer stormwater management programs that include an MTD approval process. These approvals may be implemented such that an MTD can be installed at locations only outside of an incorporated municipality in that county (e.g., Montgomery County). Or, the county approval can be used such that an Aqua-Swirl® can be installed at any location within the county (e.g., Whitfield County). The Aqua-Swirl® is approved at the following county levels:

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10 © AquaShieldTM, Inc. 2017. All rights revserved.

County State Example Municipality(s) w/in County
Ada, Highway District Idaho Boise
Hamilton Tennessee Chattanooga
Knox Tennessee Knoxville
Los Angeles California Greater Los Angeles area
Montgomery Maryland Unincorporated areas
San Diego California San Diego
Whitfield Georgia Dalton

5.5 Municipalities

A representative list of municipalities that have required some degree of Aqua-Swirl® evaluation and approval is provided below. It should again be kept in mind that this list does not include every locale where either approvals or installations have occurred.

State / Province Municipality State / Province Municipality Alabama Mobile North Carolina Hendersonville
California Santa Monica
Ontario
Hamilton
Stockton Oshawa
Georgia Alpharetta Ottawa
Hawaii Honolulu Simcoe
Idaho
Boise Toronto (pending)
Caldwell Oregon Eugene
Meridian Prineville
Indiana
Auburn
Quebec
Montréal
Fishers Port de Tois-Rivières
Indianapolis Quebec City
Maryland
Rockville Lac Mégantic
Bethesda
Tennessee
Chattanooga
Laurel Knoxville
Waldorf Murfreesboro
Michigan
Farmington Hills
Utah
Salt Lake City
Fenton South Jordan
Novi Vernal
Montana
Billings Washington (Eastern) Spokane
Bozeman Washington D.C. District of Columbia
Butte Wyoming Jackson Hole

6.0 LIMITED WARRANTY

An Aqua-Swirl® one year limited warranty comes standard with each device and covers against failure due to improper workmanship or defective materials for one year from delivery date. Liability limitations are described in the warranty which is available on request.

Table 17. BMP Performance – Influent/Effluent Water Quality.

BMP Sediment
(mg/L)
Nitrogen
(mg/L)
Phosphorus
(mg/L)
Metals –
Zn (μg/L)
Oil and
Grease
(mg/L)
Bacteria
(#/100mL) Temp Notes
Bioretention without
underdrain
0 0 0 0 0 0 Excellent Infiltration practices are assumed to have zero discharge
Bioretention with underdrain 34/15.5 * 1.68/1.14 † 0.61/0.16 * 107/46 * 30.8/2.5 ‡ 641.5/86.5 § Moderate ** Permeable Pavement without
underdrain
0 0 0 0 0 0 Excellent Infiltration practices are assumed to have zero discharge
Permeable Pavement with
underdrain
xx/17.0
†† xx/1.23 †† xx/0.09 †† xx/17 †† xx/0.018 ‡‡ No data Moderate Capture and Reuse 0 0 0 0 0 0 Excellent Infiltration practices are assumed to have zero discharge
Vegetated Roofs No data 1.3/1.63*** 0.012/0.057*** No data N/A xx/22§ Moderate Downspout Disconnection 0 0 0 0 0 0 Excellent Infiltration practices are assumed to have zero discharge
Soil Amendments 0 0 0 0 0 0 Excellent Infiltration practices are assumed to have zero discharge
Vegetated Filter Strips 114/27.6 §§ 1.12/0.66 ‡‡ 0.38/0.86 §§ 355/79 §§ No data No data Low Vegetated Swales 114/58.9 §§ No data 0.38/0.62 §§ 355/96 §§ No data 13,492/5,947 § Low Infiltration Basins 0 0 0 0 0 0 Excellent Infiltration practices are assumed to have zero discharge
Infiltration Trenches 0 0 0 0 0 0 Excellent Infiltration practices are assumed to have zero discharge
Source: Data assembled by the Low Impact Development Center, Inc.

Table 17 (Cont.): BMP Performance – Influent/Effluent Water Quality.

BMP Sediment
(mg/L)
Nitrogen
(mg/L)
Phosphorus
(mg/L)
Metals –
Zn (μg/L)
Oil and
Grease
(mg/L)
Bacteria
(#/100mL) Temp Notes
Dry Wells 0 0 0 0 0 0 Excellent Infiltration practices are assumed to have zero discharge
Dry Ponds 114/46.6 §§ 0.96/0.98 ‡‡ 0.38/0.28 §§ 355/136 §§ 2.72/2.54 ‡‡ 2,218/1,741 § Poor Constructed Wetlands 37.8/17.8 †† 2.12/1.15 †† 0.27/0.14 †† 47/31 †† No data 2,097/257 § Poor ** Wet Ponds 114/11.8 §§ 2.29/1.46 ‡‡ 0.38/0.54 §§ 355/37 §§ 0.82/0.88 ‡‡ 2,693/446.4 § Poor ** Media Filters / Filter Basins 114/11.3 §§ No data 0.38/0.25 §§ 355/36 §§ No data 1,820/541.3 § Poor Includes Austin sand filter, Delaware sand filter, Multi-
chambered treatment trains
Proprietary Devices varies varies varies varies va ries varies Poor Performance is device-specific Key: *Davis, 2007 §Clary et al, 2008 †Hunt et al, 2008 ‡Hong et al, 2006 ***Teemusk and Mander, 2007 **Jones and Hunt, 2008 §§Caltrans, 2004 ††Geosyntec, 2008 ‡‡International Stormwater BMP Database, 2009 Source: Data assembled by the Low Impact Development Center, Inc.

‐ 34 ‐

Appendix 7: Hydromodification
Supporting Detail Relating to Hydrologic Conditions of Concern

‐ 35 ‐

HCOC Applicability Map

‐ 36 ‐

Existing Stream Channel Delineation Map

‐ 37 ‐

Appendix 8: Source Control
Pollutant Sources/Source Control Checklist

‐ 38 ‐

‐ 39 ‐

‐ 40 ‐

‐ 41 ‐

‐ 42 ‐

‐ 43 ‐

‐ 44 ‐

‐ 45 ‐

‐ 46 ‐

‐ 47 ‐

‐ 48 ‐

‐ 49 ‐

Appendix 9: O&M
Operation and Maintenance Plan and Documentation of Finance, Maintenance and Recording Mechanisms

‐ 50 ‐

MaxWellIVDrywell
The Operation and Maintenance Program will include the following key components:

1. Inspection Procedures:

The settling chambers and internal components of the unit will be inspected regularly.

Additionally, an assessment of the site drainage will be conducted to insure that the system meets operation guidelines. The visual inspection will ascertain that the unit is functioning properly (no blockages or obstructions to inlet and/or infiltration chamber), measuring the amount of solid materials, fine sediment, and floating trash and debris within the chamber.

Schedules for inspections and cleanout will be based on storm events and pollutant accumulation due to failure of upstream pre-treatment device. During the rainfall season, the unit will be inspected at least once every 30 days. Accumulation of sediment and floatable material captured by the MaxWell IV will be recorded in a maintenance log.

2. Cleanout Procedures:

Truck mounted hydro-vactor equipment will be used to clean the system utilizing water and air to dislodge and remove debris and sediment deposits. All chambers, inlets, connecting piping and catch basis are cleaned and the contents discharged. The accumulated contents are transported off-site for disposal. Within each chamber, geotextile fabric base seals and hydrophobic petrochemical sponges are removed and replaced. Inlet grates and covers are re-installed and then re-secured with the existing locking devices.

3. Stenciling:

Legibility of stencils and/or signs at all storm drain inlets and catch basins within the project area must be maintained at all time.

4. Maintenance Log:

Keep on-site a log of all inspections and maintenance performed on the MaxWell IV.

Maintenance

Underground storm water detention and retention systems should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend more heavily on site activities than the size or configuration of the system.

Inspection

Inspection is the key to effective maintenance and is easily performed. CONTECH recommends ongoing quarterly inspections of the accumulated sediment. Sediment deposition and transport may vary from year to year and quarterly inspections will help insure that systems are cleaned out at the appropriate time. Inspections should be performed more often in the winter months in climates where sanding operations may lead to rapid accumulations, or in equipment washdown areas. It is very useful to keep a record of each inspection. A sample inspection log is included for your use.

Systems should be cleaned when inspection reveals that accumulated sediment or trash is clogging the discharge orifice. CONTECH suggests that all systems be designed with an access/inspection manhole situated at or near the inlet and the outlet orifice. Should it be necessary to get inside the system to perform maintenance activities, all appropriate precautions regarding confined space entry and OSHA regulations should be followed.

Cleaning

Maintaining an underground detention or retention system is easiest when there is no flow entering the system. For this reason, it is a good idea to schedule the cleanout during dry weather.

Accumulated sediment and trash can typically be evacuated through the manhole over the outlet orifice. If maintenance is not performed as recommended, sediment and trash may accumulate in front of the outlet orifice. Manhole covers should be securely seated following cleaning activities.

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Aqua-Swirl®
Stormwater Treatment System

Inspection and Maintenance Manual

AquaShieldTM, Inc.
2733 Kanasita Drive
Suite 111
Chattanooga, TN 37343
Toll free (888) 344-9044
Phone: (423) 870-8888
Fax: (423) 826-2112
Email: [email protected]
www.aquashieldinc.com

March 2014

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Table of Contents

Page(s)

 AquaShieldTM Stormwater Treatment Systems 3

 Aqua-Swirl® Stormwater Treatment System 4 – 9

 Inspection and Maintenance Worksheets and Attachments 10 – 13

 Aqua-Swirl® Tabular Maintenance Schedule 14

AquaShieldTM, Inc.
2733 Kanasita Drive
Suite 111
Chattanooga, Tennessee 37343
Toll free (888) 344-9044
Fax (423) 870-2112
www.aquashieldinc.com

Page 3 of 14 ends

AquaShield™, Inc
Stormwater Treatment Solutions

The highest priority of AquaShieldTM, Inc. (AquaShield™) is to protect waterways by providing stormwater treatment solutions to businesses across the world. These solutions have a reliable foundation based on over 20 years of water treatment experience.

Local regulators, engineers, and contractors have praised the AquaShield™ systems for their simple design and ease of installation. All the systems are fabricated from high performance, durable and lightweight materials. Contractors prefer the quick and simple installation of our structures that saves them money.

The patented line of AquaShield™ stormwater treatment products that provide high levels of stormwater treatment include the following:
 Aqua-Swirl® Stormwater Treatment System: hydrodynamic separator, which provides a highly effective means for the removal of sediment, floating debris and free- oil.

 Aqua-FilterTM Stormwater Filtration System: treatment train stormwater filtration system capable of removing gross contaminants, fine sediments, waterborne hydrocarbons, heavy metals and total phosphorous.

Aqua-Swirl® Stormwater
Treatment System
Aqua-Filter™ Stormwater
Filtration System

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Aqua-Swirl® Stormwater Treatment
System

The patented Aqua-Swirl® Stormwater Treatment System is a single chamber hydrodynamic separator which provides a highly effective means for the removal of sediment, free oil, and floating debris. Both treatment and storage are accomplished in the swirl chamber without the use of multiple or “blind” chambers. Independent laboratory and field performance verifications have shown that the Aqua-Swirl® achieves over 80% suspended solids removal efficiency on a net annual basis.

The Aqua-Swirl® is most commonly installed in an “off-line” configuration. Or, depending on local regulations, an “in-line” (on-line) conveyance flow diversion (CFD) system can be used.

The CFD model allows simple installation by connecting directly to the existing storm conveyance pipe thereby providing full treatment of the “first flush,” while the peak design storm is diverted and channeled through the main conveyance pipe.

The patented Aqua-Swirl® Stormwater Treatment System provides a highly effective means for the removal of sediment, floating debris, and free oil. Swirl technology, or vortex separation, is a proven form of treatment utilized in the stormwater industry to accelerate gravitational separation.

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Floatable debris in the Aqua-Swirl®

Each Aqua-Swirl® is constructed of high performance, lightweight and durable materials including polymer coated steel (PCS), high density polyethylene (HDPE), or fiberglass reinforced polymer (FRP). These materials eliminate the need for heavy lifting equipment during installation.

System Operation

The treatment operation begins when stormwater enters the Aqua-Swirl® through a tangential inlet pipe that produces a circular (or vortex) flow pattern that causes contaminates to settle to the base of the unit. Since stormwater flow is intermittent by nature, the Aqua-Swirl® retains water between storm events providing both dynamic and quiescent settling of solids. The dynamic settling occurs during each storm event while the quiescent settling takes place between successive storms. A combination of gravitational and hydrodynamic drag forces encourages the solids to drop out of the flow and migrate to the center of the chamber where velocities are the lowest.

The treated flow then exits the Aqua-Swirl® behind the arched outer baffle. The top of the baffle is sealed across the treatment channel, thereby eliminating floatable pollutants from escaping the system. A vent pipe is extended up the riser to expose the backside of the baffle to atmospheric conditions, preventing a siphon from forming at the bottom of the baffle.

Custom Applications

The Aqua-Swirl® system can be modified to fit a variety of purposes in the field, and the angles for inlet and outlet lines can be modified to fit most applications. The photo below demonstrates the flexibility of Aqua-Swirl® installations using a “twin” configuration in order to double the

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Custom designed AS-9 Twin Aqua-Swirl®
water quality treatment capacity. Two Aqua-Swirl® units were placed side by side in order to treat a high volume of water while occupying a small amount of space.

Retrofit Applications

The Aqua-Swirl® system is designed so that it can easily be used for retrofit applications. With the invert of the inlet and outlet pipe at the same elevation, the Aqua-Swirl® can easily be connected directly to the existing storm conveyance drainage system. Furthermore, because of the lightweight nature and small footprint of the Aqua-Swirl®, existing infrastructure utilities (i.e., wires, poles, trees) would be unaffected by installation.

AquaShield™ Product
System Maintenance

The long term performance of any stormwater treatment structure, including manufactured or land based systems, depends on a consistent maintenance plan. Inspection and maintenance functions are simple and easy for the AquaShieldTM Stormwater Treatment Systems allowing all inspections to be performed from the surface.

It is important that a routine inspection and maintenance program be established for each unit based on: (a) the volume or load of the contaminants of concern, (b) the frequency of releases of contaminants at the facility or location, and (c) the nature of the area being drained.

In order to ensure that our systems are being maintained properly, AquaShieldTM offers a maintenance solution to all of our customers. We will arrange to have maintenance performed.

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Inspection

All AquaShieldTM products can be inspected from the surface, eliminating the need to enter the systems to determine when cleanout should be performed. In most cases, AquaShieldTM recommends a quarterly inspection for the first year of operation to develop an appropriate schedule of maintenance. Based on experience of the system’s first year in operation, we recommend that the inspection schedule be revised to reflect the site-specific conditions encountered. Typically, the inspection schedule for subsequent years is reduced to semi-annual inspection.

Aqua-Swirl® Maintenance

The Aqua-Swirl® has been designed to minimize and simplify the inspection and maintenance process. The single chamber system can be inspected and maintained entirely from the surface thereby eliminating the need for confined space entry. Furthermore, the entire structure (specifically, the floor) is accessible for visual inspection from the surface. There are no areas of the structure that are blocked from visual inspection or periodic cleaning. Inspection of any free- floating oil and floatable debris can be directly observed and maintained through the manhole access provided directly over the swirl chamber.

Aqua-Swirl® Inspection Procedure

To inspect the Aqua-Swirl®, a hook is needed to remove the manhole cover. AquaShieldTM provides a customized manhole cover with our distinctive logo to make it easy for maintenance crews to locate the system in the field. We also provide a permanent metal information plate

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Sediment inspection using a
stadia rod in a single chamber
Maintenance trigger for Aqua-Swirl® Models AS-
3 through AS-13 occurs when sediment pile is
42-48 inches below water surface.

Maintenance trigger for Aqua-Swirl® Model
AS-2 occurs when sediment pile is 30 to 32
inches below water surface.
affixed inside the access riser which provides our contact information, the Aqua-Swirl® model size, and serial number.

The only tools needed to inspect the Aqua-Swirl® system are a flashlight and a measuring device such as a stadia rod or pole. Given the easy and direct accessibility provided, floating oil and debris can be observed directly from the surface. Sediment depths can easily be determined by lowering a measuring device to the top of the sediment pile and to the surface of the water.

The maintenance trigger for Aqua-Swirl® Models AS-3 through AS-13 occurs when the sediment pile is within 42 to 48 inches of the standing water surface. For the Aqua-Swirl® Model AS-2, maintenance is needed when the top of the sediment pile is measured to be 30 to 32 inches below the standing water surface.

It should be noted that in order to avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. Keep in mind that the finer sediment at the top of the pile may offer less resistance to the measuring device than the larger particles which typically occur deeper within the sediment pile.

”
42-48”
AS-2:
30-32”

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Vacuum truck quickly cleans the Aqua-Swirl®
from a single chamber
The Aqua-Swirl® design allows for the sediment to accumulate in a semi-conical fashion as illustrated above. That is, the depth to sediment as measured below the water surface may be less in the center of the swirl chamber; and likewise, may be greater at the edges of the swirl chamber.

Aqua-Swirl® Cleanout Procedure

Cleaning the Aqua-Swirl® is simple and quick. Free-floating oil and floatable debris can be observed and removed directly through the 30-inch service access riser provided. A vacuum truck is typically used to remove the accumulated sediment and debris. An advantage of the Aqua-Swirl® design is that the entire sediment storage area can be reached with a vacuum hose from the surface (reaching all the sides). Since there are no multiple or limited (hidden or “blind”) chambers in the Aqua-Swirl®, there are no restrictions to impede on-site maintenance tasks.

Disposal of Recovered Materials

Disposal of recovered material is typically handled in the same fashion as catch basin cleanouts.

AquaShieldTM recommends that all maintenance activities be performed in accordance with appropriate health and safety practices for the tasks and equipment being used.

AquaShieldTM also recommends that all materials removed from the Aqua-Swirl® and any external structures (e.g, bypass features) be handled and disposed in full accordance with any applicable local and state requirements.

Aqua-Swirl® Inspection and Maintenance Work Sheets
on following pages

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Aqua-Swirl® Inspection and Maintenance Manual
Work Sheets

SITE and OWNER INFORMATION

Site Name:

Site Location:

Date: Time:

Inspector Name:

Inspector Company: Phone #:

Owner Name:

Owner Address:

Owner Phone #: Emergency Phone #:

INSPECTIONS

I. Floatable Debris and Oil

1. Remove manhole lid to expose liquid surface of the Aqua-Swirl®.

2. Remove floatable debris with basket or net if any present.

3. If oil is present, measure its depth. Clean liquids from system if one half (½) inch or more oil is present.

Note: Water in Aqua -Swirl® can appear black and similar to oil due to the dark body of the surrounding structure. Oil may appear darker than water in the system and is usually accompanied by oil stained debris (e.g. Styrofoam, etc.). The depth of oil can be measured with an oil/water interface probe, a stadia rod with water finding paste, a coliwasa, or collect a representative sample with a jar attached to a rod.

II. Sediment Accumulation

1. Lower measuring device (e.g. stadia rod) into swirl chamber through service access provided until top of sediment pile is reached.

2. Record distance to top of sediment pile from top of standing water: inches

3. For Aqua-Swirl® Models AS-3 through AS -13, schedule cleaning if value in Step # 2 is 48 to 42 inches or less.

4. For Aqua-Swirl® Model AS-2, schedule cleaning if value in Step #2 is 32 to 30 inches or less.

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III. Diversion Structures (External Bypass Features)

If a diversion (external bypass) configuration is present, it should be inspected as follows:

1. Inspect weir or other bypass feature for structural decay or damage. Weirs are more susceptible to damage than off -set piping and should be checked to confirm that they are not crumbling (concrete or brick) or decaying (steel).

2. Inspect diversion structure and bypass piping for signs of structural damage or blockage from debris or sediment accumulation.

3. When feasible, measure elevations on diversion weir or piping to ensure i t is consistent with site plan designs.

4. Inspect downstream (convergence) structure(s) for sign of blockage or structural failure as noted above.

CLEANING

Schedule cleaning with local vactor company or AquaShieldTM to remove sediment, oil and other floatable pollutants. The captured material generally does not require special treatment or handling for disposal. Site -specific conditions or the presence of known contaminants may necessitate that appropriate actions be taken to clean and dispose of materia ls captured and retained by the Aqua -Swirl®. All cleaning activities should be performed in accordance with property health and safety procedures.

AquaShieldTM always recommends that all materials removed from the Aqua -Swirl® during the maintenance process be handled and disposed in accordance with local and state environmental or other regulatory requirements.

MAINTENANCE SCHEDULE

I. During Construction

Inspect the Aqua -Swirl® every three (3) months and clean the system as needed. The Aqua-Swirl® should be inspected and cleaned at the end of construction regardless of whether it has reached its maintenance trigger.

II. First Year Post-Construction

Inspect the Aqua-Swirl® every three (3) months and clean the system as needed.

Inspect and clean the syste m once annually regardless of whether it has reached its sediment or floatable pollutant storage capacity.

III. Second and Subsequent Years Post-Construction

If the Aqua-Swirl® did not reach full sediment or floatable pollutant capacity in the First Year Post-Construction period, the system can be inspected and cleaned once annually.

If the Aqua -Swirl® reached full sediment or floatable pollutant capacity in less than 12 months in the First Year Post -Construction period, the system should be inspected once

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every six (6) months and cleaned as needed. The Aqua-Swirl® should be cleaned annually regardless of whether it reaches its sediment or floatable pollutant capacity.

IV. Bypass Structures

Bypass structures should be inspected whenever the Aqua -Swirl® is ins pected.

Maintenance should be performed on bypass structures as needed.

MAINTENANCE COMPANY INFORMATION

Company Name:

Street Address:

City: State/Prov.: Zip/Postal Code:

Contact: Title:

Office Phone: Cell Phone:

ACTIVITY LOG

Date of Cleaning: (Next inspection should be 3 months from this data for first year).

Time of Cleaning: Start: End:

Date of Next Inspection:

Floatable debris present: Yes No

Notes:

Oil present: Yes No Oil depth (inches):

Measurement method and notes:

STRUCTURAL CONDITIONS and OBSERVATIONS

Structural damage: Yes No Where:

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Structural wear: Yes No Where:

Odors present: Yes No Describe:

Clogging: Yes No Describe:

Other Observations:

NOTES

Additional Comments and/or Actions To Be Taken Time Frame

ATTACHMENTS

 Attach site plan showing Aqua-Swirl® location.

 Attach detail drawing showing Aqua-Swirl® dimensions and model number.

 If a diversion configuration is used, attach details showing basic design and elevations (where feasible).

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Aqua-Swirl®

TABULAR MAINTENANCE SCHEDULE

Date Construction Started:

Date Construction Ended:

During Construction

Month
Activity 1 2 3 4 5 6 7 8 9 10 11 12
Inspect and Clean
as needed X X X X
Inspect Bypass and
maintain as needed X X X X
Clean System* X*
* The Aqua-Swirl® should be cleaned once a year regardless of whether it has reached full pollutant storage capacity. In addition, the system should be cleaned at the end of construction regardless of whether it has reach full pollutant storage capacity.

First Year Post-Construction

Second and Subsequent Years Post-Construction

Month
Activity 1 2 3 4 5 6 7 8 9 10 11 12
Inspect and Clean
as needed X*
Inspect Bypass,
maintain as needed X*
Clean System* X*
* If the Aqua-Swirl® did not reach full sediment or floatable pollutant capacity in the First Year Post-Construction period, the system can be inspected and cleaned once annually.

If the Aqua-Swirl® reached full sediment or floatable pollutant capacity in less than 12 months in the First Year Post-Construction period, the system should be inspected once every six (6) months or more frequently if past history warrants, and cleaned as needed. The Aqua-Swirl® should be cleaned annually regardless of whether it reaches its full sediment or floatable pollutant capacity.

‐ 51 ‐

Appendix 10: Educational Materials
BMP Fact Sheets, Maintenance Guidelines and Other End‐User BMP Information

To be included with Final WQMP.

Riverside City CouncilJuly 14, 2026

Riverside City Council
July 14, 2026