FAIRFIELD-SUISUN URBAN RUNOFF MANAGEMENT PROGRAM · 2011-10-04 · Stormwater Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program “Deemed Complete”

FAIRFIELD-SUISUN URBAN RUNOFF MANAGEMENT PROGRAM

Storm Water Requirements

For Development Projects— Packet for Project Applicants

May 10, 2006

Fairfield-Suisun Urban Runoff Management Program Stormwater Requirements for Development Projects

Packet for Project Applicants This packet is designed to help project proponents of new and redevelopment projects understand and comply with the stormwater requirements for the Cities of Fairfield and Suisun City. City staff and Fairfield-Suisun Sewer District staff are required to address protection of stormwater quality during development review and implement stormwater controls for many new and redevelopment projects. This packet contains eight sections as discussed below. PAGE I. Application, Overview and Applicability ........................................................1

This section provides a basic understanding of the stormwater control requirements and describes which projects are applicable. The New and Redevelopment Post Construction Stormwater Requirements Application is included at the end of this section.

II. Construction Requirements Guidance Documents ........................................9

This section provides a list of guidance documents that are useful for construction requirements. These requirements, which are not new to the NPDES permit, are not detailed within the packet.

III. Site Design and Source Control Requirements .............................................10

This section provides valuable information on designing the site to include best management practices (BMPs).

IV. Treatment Controls .........................................................................................11

This section discuses the benefits of treatment BMPs and provides guidance on the sizing of treatment control systems.

V. Operations and Maintenance .........................................................................16

This section provides information on the Stormwater Treatment Measures Maintenance Agreement and other operation and maintenance requirements.

VI. CEQA ................................................................................................................16

This section includes information about CEQA and how it pertains to stormwater quality. Information can help complete the CEQA initial study checklist.

VII Guidance for Completing the New and Redevelopment Post Construction

Stormwater Requirements Application .........................................................18 This section provides information about the New and Redevelopment Post Construction Stormwater Requirements Application and definitions about the information fields in the form.

VIII. Additional Resources and Contacts ...............................................................20

This section includes additional resources and contacts that may be useful for project applicants. The section includes a glossary.

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APPENDICES Appendix A: Design Drawings for Common Source Controls

• SW-1: Car Wash Exit • SW-2: Loading Dock • SW-3: Business/Commercial Trash Enclosure • SW-4: Fueling Area

Appendix B: Stormwater Pollution Control Measures List Appendix C: Stormwater Treatment Requirement Worksheets

I. Initial Data Needs II. FSURMP Simplified Method for Sizing Flow-based Treatment Measures III. FSURMP Simplified Method for Sizing Volume-based Treatment Measures

Attachment 1.0: Worksheets for Using Other Options Allowed in FSURMP Permit to Size Controls

Attachment 2.0: Example Worksheets for Determining Treatment Amounts: Village Apartments

Attachment 3.0: Example Calculations for Sizing a Vegetated Swale: Village Apartments (Flow-based Control)

Attachment 4.0: Example Calculations for Sizing a Detention Basin: Village Apartments (Volume-based Control)

Appendix D: Model Operations and Maintenance Agreement PAGE TABLES Table 1: Design Criteria Guidance for Vegetated Swales and Detention Basins .............18 Appendix C

Table C.1: Examples of Flow-based and Volume-based Controls.........................C-1 Table C.2a: Estimated Runoff Coefficients for Various Surfaces During

Small Storms.........................................................................................C-2 Table C.2b: Estimated Composite Runoff Coefficients for Small Storms

by Land Use .........................................................................................C-2 Table C.3: Unit Storage Volume for 80% Capture................................................C-6

FIGURES Appendix C

Figure 1: Mean Annual Precipitation for Cities of Fairfield and Suisun City .........C-8

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Stormwater Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program

I. OVERVIEW AND APPLICABILITY

It’s Federal Law Urban stormwater runoff is a significant source of pollutants to the nation’s waters. In 1987, Congress began to address this problem by requiring municipal stormwater programs to obtain National Pollutant Discharge Elimination System (NPDES) permits. This resulted in local requirements for runoff from development projects.

The Local Stormwater Program In Fairfield and Suisun City, development projects must comply with the NPDES permit issued to the Fairfield-Suisun Urban Runoff Management Program (FSURMP) by the San Francisco Bay Regional Water Quality Control Board (Water Board). The FSURMP permit was reissued in April 2003 with substantial new requirements for development and redevelopment projects.

How it Works Locally The City of Fairfield, City of Suisun City and Fairfield-Suisun Sewer District are required to address stormwater quality during development review. Projects must use best management practices (BMPs) during construction to mitigate impacts from construction work and during post construction to mitigate post-construction impacts to water quality. Long-term water quality impacts must be reduced using site design and source control measures to help keep pollutants out of stormwater. You can save a good amount of money by avoiding and mitigating stormwater impacts early in the project planning phase. This applicant package is designed to assist you in minimizing these impacts.

What Is Required of All Projects? Sections II (Construction Requirements), III (Site Design and Source Control Requirements) and VI (CEQA considerations) of this packet are applicable to all projects. All construction projects have to use construction BMPs and implement appropriate site design and source control measures to reduce pollutant discharges in stormwater. Projects that meet a certain size threshold of impervious surface1 coverage must meet more stringent standards.

What Is Changing? FSURMP’s permit includes specific requirements for projects that meet “Group 1” and “Group 2” criteria (see description below). The permit requires Permittees to enhance their site design and source control standards, and treatment control requirements. Is My Project in “Group 1”? Group 1 projects include new development and redevelopment projects that create or replace one acre or more of impervious surface1. The Stormwater Development Requirements Applicability Flow Chart and the FSURMP New and Redevelopment Stormwater Requirements Application will help you determine if your project meets the thresholds (see page 3 and 5). Group 1 project applications deemed complete on or after April 16, 2005 are required to meet the new stormwater requirements.

1 “Impervious surface” is defined as constructed or modified surface that cannot effectively infiltrate rainfall. Impervious surface includes but is not limited to building rooftops, pavement, sidewalks, and driveways where such surfaces are not constructed with pervious materials.

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Stormwater Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program “Deemed Complete” Definition. The City reviews development applications within 30 days of submittal to determine whether all the required information has been provided and the application can be “deemed complete” and accepted. If the application submittal is incomplete, staff sends a letter to the applicant indicating that the application is “deemed incomplete” and lists the items needed to complete the application. If the Planning Division’s written determination is not made within 30 days after receipt of the application, under State Law, it is deemed “complete” and staff proceeds with processing the application.

Is My Project in “Group 2”? The Group 2 definition is the same as the Group 1 definition, except that the size threshold is reduced from one acre to 10,000 square feet of impervious surface.2 Group 2 thresholds take effect for projects deemed complete on or after October 16, 2006.

Projects Exempt from the New and Redevelopment Group Requirements Some projects are exempt from the Group 1 and 2 new and redevelopment requirements (see below). If your project is not included in this list, refer to the flow chart (on the following pages) to determine what additional stormwater requirements should be included within your project. Land Use Category Exempted Land Use Residential developments Construction of one single-family home that is not part of a

larger common plan of development, with the incorporation of appropriate pollutant source control and design measures, and the use of landscaping to appropriately treat runoff from roof and house-associated impervious surfaces (e.g., runoff from roofs, patios, driveways, sidewalks, and similar surfaces), would be in substantial compliance with the stormwater requirements.

Street, road, highway, and freeway projects that are under the City’s or District’s jurisdiction

Sidewalks, bicycle lanes, trails, bridge accessories, guardrails, and landscape features that are part of a street, road, highway or freeway project are exempt. Note: These are not exempt when they are part of commercial, industrial or residential developments.

Significant redevelopment projects

Interior remodels and routine maintenance or repair (e.g., roof or exterior surface replacement, pavement resurfacing, repaving and road pavement structural section rehabilitation within the existing footprint, and any other reconstruction work within a public street or road right-of-way where both sides of that right-of-way are developed).

So I Need to Meet the Stormwater Requirements, Now What? In addition to construction BMPs (see Section II), site design and source controls (see Section III), Group 1 (and ultimately Group 2) projects will need to include stormwater treatment measures (See Section IV). In certain areas of Fairfield where increased runoff flow and volume may cause excessive creek or storm erosion, projects may need to control the quantity of stormwater runoff (contact Gene Cortright at (707) 428-7488 for more information on Hydrograph Modification Management Plan (HMP) requirements).

2 Permit Provision C.3 of the FSURMP NPDES permit details Group 1 and 2 definitions and exemptions. The 10,000 square foot threshold for Group 2 may be modified prior to October 15, 2006. Please check with your local representative.

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Fairfield-Suisun Urban Runoff Management Program Stormwater New and Redevelopment Requirements

Applicability Flow Chart Start Here

Is the project an exempted land

use? (see page 2)

Yes

Was the application deemed complete before

April 16, 2005?

No

Yes

Will the project create or replace > 1 acre (43,560 sf) of

impervious surface?

No The project must incorporate site, source control and stormwater treatment BMPs.

If the project disturbs > 1 acre of land area during construction, it must obtain coverage under State General Construction Activity Permit: submit NOI, and prepare SWPPP.

All development sites must have a SWPPP prior to the start of construction.

Is >50% of the existing impervious surface area going to be replaced or

added?

Include entire project in the design of treatment measures.

See FSURMP NPDES Permit page 21 for more details regarding applicability.

Proceed with steps in review process required for stormwater new and

redevelopment requirements (NPDES Permit Provision C.3).

Include only the affected portion of the redevelopment site in the design of treatment measures.

Yes

The FSURMP NPDES Permit new and redevelopment stormwater requirements are not applicable to the project.

Promote the incorporation of site design and source control measures to protect water quality.

If the project disturbs > 1 acre of land area during construction, must obtain coverage under State General Construction Activity Permit: submit NOI; prepare SWPPP.

All development sites must have a SWPPP prior to the start of construction.

Yes

Is the project a redevelopment project?

No

Yes, this is a Group 2 Project

Yes, this is a Group 1 Project

Will the project create or replace > 10,000 sq. ft. of impervious surface?

No

No Was the application

deemed complete before October 16, 2006?

No

Yes No

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NEW AND REDEVELOPMENT POST CONSTRUCTION

STORMWATER REQUIREMENTS APPLICATION

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FAIRFIELD-SUISUN STAFF ONLY URBAN RUNOFF MANAGEMENT PROGRAM Date of Building

Permit: ________ Permit #: _______

NEW AND REDEVELOPMENT POST CONSTRUCTION STORM WATER REQUIREMENTS APPLICATION

What Projects Apply?

All projects creating, adding, or replacing 43,560 sq. ft. (1 acre) or more of impervious surface on the project site must fill out this worksheet and submit it to the Building Division. Interior remodeling projects and routine maintenance or repair projects, and projects involving only construction of sidewalks, bicycle lanes, trails, bridge accessories, guardrails, and landscape features are NOT required to complete this worksheet. What is an Impervious Surface?

An impervious surface prevents the infiltration or passage of water into the soil. Onsite impervious surfaces include building rooftops, paved patios, covered patios, driveways, parking lots, paved walkways, sidewalks and streets.

Project Name: ____________________________________APN #__ __ __ - __ __ - __ __ __ Project Description: ____________________________________________________________ Applicant Name: Project Location: (address)

Project Location: (watershed) (receiving water)

1. Project Type (Check one): New Development Redevelopment

2. Project Use (Check one):

Residential Commercial Industrial Public Road

Multi-use Other:___________________

If Residential, does the project consist of a single-family home that is not part of a larger common plan of development? Yes No

If yes, skip to Question 3. The project will be considered in compliance with the storm water requirements with the incorporation of appropriate pollutant source control and site design measures, and the use of landscaping to appropriately treat runoff from the roof and house-associated impervious surfaces (e.g., runoff from roofs, patios, driveways, sidewalks, and similar surfaces). * NOTE: After October 15, 2006, the threshold will be reduced to 10,000 sq. ft. or other minimum project size. See municipal stormwater staff for information.

Page 1 of 4 Rev. 06/1/06

3. Project size:

a. Site size sq. ft.

b. Existing impervious surface area (includes land covered by buildings, sheds, patios/covers, parking lots, streets, sidewalks, paved walkways and driveways onsite) sq. ft.

c. Impervious surface area created, added, or replaced sq. ft.

d. Total impervious surface area (new + existing) sq. ft.

e. Percent increase/replacement of impervious surface area______________________ % c/b(100%)

f. Estimated area of land disturbance during construction ______________________ sq. ft.(including clearing, grading, or excavating).

4. Type of Pesticide Reduction Measures Used (Check all that apply): Education (e.g., fact sheet, plant list) Conditions of Approval Does not Apply Other (Describe:________________________________________________________)

5. Types of Stormwater Controls Used (check all that apply, using lists at end):

Treatment Measures Source Control Measures Site Design Measures

6. Hydromodification Management Plan Applicability: a. Direct Discharge Point of Project:

Municipal Storm Drain System Creek Suisun Bay

b. Receiving Body Exempt? Yes No

Page 2 of 4 Rev. 06/1/06

7. Specific Stormwater Treatment and Control Measures:

Site Design

Minimize land disturbance

Minimize impervious

surfaces

Minimum-impact street design (narrow residential streets, roadside swales)

Minimum-impact parking

lot design

Cluster structures/ pavement

Porous/Permeable

pavement *

Alternative driveway design

Disconnect downspouts

Microdetention in

landscape *

Preserve open space: _______ ac. or ft. (circle one)

Protect riparian and

wetland areas, riparian buffers (Setback from top of bank: _______ft.)

Other _______________

* Note: Needs maintenance

Source Controls

Alternative Building Materials

Wash area/racks, drain to

sanitary sewer

Covered dumpster area, drain to sanitary sewer

Swimming pool/fountain

drain to sanitary sewer

Beneficial landscaping (minimizes irrigation, runoff, pesticides and fertilizers; promotes treatment)

Outdoor material storage

protection

Covers, drains for loading docks, maintenance bays, fueling areas

Maintenance (street

sweeping, catch basin cleaning)

Storm Drain Signage

Green or Blue Roofs

Other _______________

Stormwater Treatment

Vegetated Swale

Vegetated Buffer Strip

Bioretention

Extended Detention basin (dry)

Wet Pond/Constructed

wetland (basin or channel) (retention)

Underground detention

(e.g. Porous Pavement Recharge Bed)

Media filter (sand, organic

matter, manufactured)

Hydrodynamic Separator Device (commercially available in-line treatment unit e.g., CDS, wet vault, vortex separator)

Retention/Irrigation

Water Quality Inlet/

Oil/Water Separators

Roof Garden/Green Roofs (rooftop vegetation)

Planter Boxes

Exfiltration Trench

Other ______________

Page 3 of 4 Rev. 06/1/06

8. Treatment Control Details

For each treatment control measure included as part of your project, provide the name and the sizing method used (See Appendix C). Use additional sheets if necessary

Treatment Control BMP Sizing Method Used (e.g. FSURMP Simplified Flow; FSURMP Simplified Volume; Factored Flow (Attachment 1A.a), CA BMP Handbook Flow (Attachment 1A.b); URQM Volume (Attachment 1B))

1.

2.

A. Property Owners Name _________________________________________ B. Responsible Party—Stormwater Treatment Measure Owner or Operator’s Information:

a. Name: _________________________________________ b. Address: _________________________________________ c. Phone/Fax/E-mail: _________________________________________

NOTE: A detailed sheet of construction drawings and calculations for properly sized storm water treatment controls will be required with the building permit submittal. Proof of records from the County Assessor’s Office will be required prior to issuance of the building permit.

This section to be completed by Municipal staff More Detailed Information about Access Assurance and O&M Responsibilities: Describe how access permission is assured for O&M verification by public agencies or their representatives (e.g., City, Fairfield-Suisun Sewer District, Regional Water Quality Control Board, and Solano County Mosquito Abatement District): ____________________________________________________________________________________ ____________________________________________________________________________________ Indicate how responsibility for O&M is assured. Check all that apply:

Signed statement from private entity accepting responsibility for O&M until responsibility is legally transferred. Signed statement from public entity assuming O&M and that the treatment measures meet all local design standards. Written conditions in the sales or lease agreement requiring the buyer or lessee to assume O&M (in the case of purchase and sale

agreements, conditions shall survive the close of escrow). Written text in project conditions, covenants and restrictions for residential properties assigning O&M responsibilities to the

homeowners association. Any other legally enforceable agreement or mechanism that assigns responsibility and describe below.

_____________________________________________________________________________________ Local Agency O&M Verification Program Name of municipality or Flood Control District responsible under the NPDES permit for verifying O&M. __________________________________________________________________________________ Describe where information documenting responsibility for O&M is kept and updated. ____________________________________________________________________________________ ____________________________________________________________________________________ Reviewed: Planning and Development Department Public Works Department

Planning Division: ________ Engineering Division: ________

Other (Specify) ___________________________ Building Division: ________ Return copy of completed form to: Kevin Cullen ([email protected]) Data entry performed by: ________ Fairfield-Suisun Sewer District 1010 Chadbourne Road Fairfield, CA 94534-9700 Page 4 of 4 Rev. 06/1/06


II. CONSTRUCTION REQUIREMENTS GUIDANCE DOCUMENTS

There are many methods of preventing stormwater pollution during construction activities. The requirements relating to how to prevent erosion and how to control sediment from entering runoff during the construction process can be found in supplemental brochures for construction requirements. This section gives a brief description of construction requirements and provides guidance on where to find more comprehensive information to comply with these requirements. What’s Required During Construction? A primary source of stormwater pollution is construction sites. The largest causes of stormwater pollution from construction sites are poor erosion and sediment control, poor housekeeping practices, and poor material management. Many contractors are familiar with BMPs that are required at project sites including:

Prepare and implement sediment and erosion control plans; •

•

•

Control exposed soil by stabilizing slopes; and

Control sediment in runoff using sand bag barriers or straw wattles. All development sites in the Fairfield-Suisun area must have a Stormwater Pollution Prevention Plan (SWPPP) prior to the start of construction. Sites disturbing less than one acre of soil may have an abbreviated SWPPP. Sites disturbing one acre or more of soils must comply with the State Water Resources Control Board’s General Construction Activity Permit. Additional Resources The following resources should assist you in meeting the stormwater construction requirements. Some resources are available from the Cities or the Fairfield-Suisun Sewer District.

• FSURMP brochure on NPDES General Permit for Stormwater Discharges Associated With Construction Activity

• FSURMP brochure on Construction Erosion and Sediment Controls – Resources for Developers, Builders and Project Proponents (2006)

• FSURMP, SWPPP, CD-ROM

• Bay Area Stormwater Management Agencies Association (BASMAA) – Blueprint for a Clean Bay (2003)

• California Regional Water Quality Control Board San Francisco Bay Region – Guidelines for Construction Projects (2003)

• California Regional Water Quality Control Board San Francisco Bay Region – Erosion and Sediment Control Field Manual (August 2002 or latest)

• Association of Bay Area Governments – Manual of Standards for Erosion and Sediment Control Measures (May 1995)

• FSURMP – Trifold Brochures

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III. SITE DESIGN AND SOURCE CONTROL REQUIREMENTS All sites must consider site design and source controls. The use of site designs can help minimize the need for treatment controls as described in Section IV. Site Design for Water Quality Site design measures integrate basic stormwater management and hydrological concepts into site planning to create developments that mitigate the impact on stormwater quality. This often includes working with the natural topography, locating the development on the least sensitive portions of a site while protecting sensitive areas, and using design techniques to minimize and infiltrate runoff. Some of the many ways to reduce water quality impacts through site design include:

•

•

•

•

•

•

Reduce impervious surfaces;

Drain rooftop downspouts to lawns or other landscaping; and

Use landscaping as a storm drainage and treatment feature for paved surfaces. Incorporating water-quality friendly site design can save you money by reducing the costs of construction materials (e.g. fewer stormwater drain pipes, less pavement) and reducing maintenance of stormwater treatment controls. Site design can also enhance the aesthetic potential of the site by using protected sensitive areas as a selling point for uniqueness of property. For more information on how to save time and money by incorporating site design and source controls early in the design process, consult the following resources from the Bay Area Stormwater Management Agencies Association (BASMAA). They are available for free download on the City’s websites:

• BASMAA, “Start at the Source,” 1999

• BASMAA, “Using Site Design Techniques to Meet Development Requirements,” 2003

What is Source Control? Source control is about keeping sources of pollution away from stormwater. Some source control measures include:

Roofs over trash enclosures and loading docks,

Sanitary sewer drains in covered parking structures and vehicle wash areas; and

Indoor washracks for mats and equipment.

Stormwater runoff drains to a detention basin in Cordelia.

Design guideline drawings for four common source controls – car wash exits, loading dock drainage, trash enclosures and fueling areas – have been included in Appendix A.

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Integrated Pest Management When it rains, pesticides used to maintain landscaping and gardens are washed off the plants and soils upon which they have been applied. This stormwater runs off the land and flows to the nearest storm drain, which ultimately carries the stormwater to local creeks, the Suisun Marsh and Suisun Bay without treatment. The State of California has found that pesticides carried within stormwater maybe harmful to fish and other organisms. Therefore, reducing the use of pesticides in landscape maintenance helps protect water quality, aquatic life and human health.

When designing your project and landscaping, consider using designs that discourage pests. As you set up the necessary operation and maintenance requirements for the project, consider pest resistant plants and promoting integrated pest management (IPM) methods of pest control. IPM is a decision-making process for managing pests. This approach uses monitoring to determine pest-caused injury levels and the most effective methods for pest control. To effectively control pests while minimizing pesticide usage, IPM uses a combination of biological controls (e.g., natural enemies or predators); physical or mechanical controls (e.g., hand labor or mowing); cultural controls (e.g., mulching, disking, or alternative plant type selection); and reduced risk chemical controls (e.g., soaps or oils). If pesticides are necessary, IPM methods will use the least hazardous pesticides available as a last resort for controlling pests. For more information on pesticide reduction in landscape maintenance and design, please refer to the FSURMP brochure entitled “Landscape Maintenance Techniques for Pest Reduction.” Stormwater Pollution Control Measures List This list, included in Appendix B, includes measures that the Cities or District may require as conditions of approval on projects, as appropriate. The list describes some of the stormwater control measures that may be included into your project. The Cities or District staff can designate which measures will be required for a specific project. Both site design and source control measures can be implemented, many which are designed to reduce the amount of impervious surface area. By reducing the amount of impervious surface area on your project, you reduce the amount of area requiring more costly treatment BMPs.

IV. TREATMENT CONTROLS Stormwater treatment controls are landscape or structural systems designed to treat or remove pollutants in stormwater or to reduce the amount or rate of stormwater. Stormwater treatment BMPs are required for non-exempt Group 1 and Group 2 (after October 16, 2006) projects (see Section I). Treatment controls include detention basins, water quality wetlands, vegetated swales, bioretention, filters and solid separators. This section focuses on permanent, post-construction treatment systems rather than those treatment controls placed temporarily during the construction process (e.g., temporary detention basins and other treatment measured designed to remove sediment from stormwater at construction grading sites).

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Stormwater Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program Stormwater Treatment Methods Stormwater treatment shall be accomplished through the implementation of site design/landscape characteristics or structural controls that maximize infiltration (where applicable considering location and soil type). In addition, stormwater treatment shall provide retention or detention, slow runoff, remove pollutants and minimize impervious land coverage so that post-development pollutant loads from a site will be reduced to the maximum extent practicable. Sizing Treatment Controls The sizing of selected stormwater treatment BMPs must meet specific criteria. This section explains the required hydraulic sizing criteria. Worksheets and sizing curves to assist in sizing various treatment systems are provided. The sizing must be certified by qualified firms/personnel (e.g., City or District staff, BASMAA’s List of Qualified Firms or those otherwise appropriately trained, as deemed by the Cities or District). Project engineers should determine the sizing calculations and verify that adequate area is available for post-construction BMPs at the conditioning part of the development approval process. The calculations for the sizing of post- construction BMPs should be submitted for approval during the building permit application process. Volume Hydraulic Design Basis. The stormwater regulations allow you to size treatment measures whose primary mode of action depends on volume capacity (e.g., detention/retention units or infiltration structures) by one of two methods. According to the permit, they shall be designed to treat stormwater runoff equal to:

1. The maximized stormwater quality capture volume for the area, based on historical rainfall records, determined using the formula and volume capture coefficients set forth in Urban Runoff Quality Management, WEF Manual of Practice No. 23/ ASCE Manual of Practice No. 87, (1998), pages 175-178 (e.g., approximately the 85th percentile 24-hour storm runoff event); or

2. The volume of annual runoff required to achieve 80 percent or more capture, determined in accordance with the methodology set forth in Appendix D of the California Stormwater Best Management Practices Handbook, (1993), or as specified in subsequent editions of this handbook, using local rainfall data. (FSURMP preferred method)

Flow Hydraulic Design Basis. The stormwater regulations allow project proponents to size treatment measures whose primary mode of action depends on flow capacity (e.g., swales, sand filters or wetlands) in one of three different methods. The measures shall be sized to treat:

1. 10% of the 50-year peak flow rate; or

2. The flow of runoff produced by a rain event equal to at least two times the 85th percentile hourly rainfall intensity for the applicable area, based on historical records of hourly rainfall depths; or

3. The flow of runoff resulting from a rain event equal to at least 0.2 inches per hour intensity. (FSURMP preferred method)

Stormwater Treatment Sizing Worksheets. To assist you in determining if your project requires stormwater treatment controls, use the flow chart on page 3. If your project requires treatment controls, use the stormwater treatment control sizing worksheets. These worksheets, 12

Stormwater Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program which are provided within Appendix C, contain detailed instructions on how to compute the required volume or flow rate to be treated, depending on the type of control measure (flow-based or volume-based). Additional sizing steps will be needed depending on which BMP is selected. Additional Information for Designing Selected BMPs Vegetated Swale. To design a swale, one must determine the swale slope, select the vegetation cover, determine the vegetation height, select the roughness coefficient or “Manning's n” value (typically 0.20 for routinely mowed grass-lined swales) and select the cross-sectional shape of the swale (typically parabolic or trapezoidal). Manning’s Equation is used to determine the swale width.

Manning’s equation3: Q = 1.49/n × R2/3 × S1/2 × A Where Q = Flow

n = Roughness Coefficient (“Manning’s n”) R = Hydraulic Radius = A / (b + 2y) for rectangular channels S = Slope of swale A = Cross-sectional Area = b × y for rectangular channels y = Flow Depth = Vegetation Height for Treatment Swale b = Swale Width

General design criteria guidance for vegetated swales is included within Table 1. An example calculation for designing a swale is provided within Appendix C, Attachment 3 (page C.3-1). Detention Basins. Design information for detention basins can be found within Table 1. Example calculations for designing a detention basin are included in Appendix C, Attachment 4 (page C.4-1). In some cases, the applicant may wish to install a detention basin that meets both flood control and water quality requirements. Combined flood control and water quality basins must be designed so the outlet mechanisms function appropriately to achieve pollutant capture goals for the small, frequent events; and safely to manage or control releases associated with much larger, infrequent storms. In addition, the basin must be designed to maintain structural integrity for storm events above the basin’s design storm capacity. Additional information on combined systems can be found in FSURMP “Guidance for Design of Detention Basins for Water Quality Improvements” (April 1996), available through the City or District. BMP Guidance Table. To provide further guidance on BMP design, Table 1 on the next page includes guidelines for two commonly used treatment controls: vegetated swale and extended detention basin. The guidelines include information for determining the hydraulic residence time, appropriate size and shape, recommended types of vegetation and other information. For more detailed information on sizing BMPs, refer to the following documents: BASMAA’s Using Site Design Techniques to Meet Development Requirements; California BMP Handbooks (New Development and Redevelopment); and FSURMP “Guidance for Design of Detention Basins For Water Quality Improvements.” Full references are provided in Section VIII.

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3 Source: BASMAA’s Using Site Design Techniques to Meet Development Requirements, 2003.

Stormwater Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program Table 1:•Design Criteria Guidance for Vegetated Swales and Detention Basins Treatment

Control Hydraulic Residence

Time/Drain Time

Sizing/Shape

Vegetation

Other

Vegetated swale

10 minutes hydraulic

residence time and may be

used as design criterion

(CASQA and COL)

1. Will occupy an area equal to at least 2.75% of site’s total impermeable area. (SAS)

2. Size to capture and treat runoff from one of the flow-based hydraulic design criteria allowed by permit. (NPDES permit)

3. The swale should have a length that provides minimum hydraulic residence time of 10 minutes. (CASQA) (As an example, a swale length of 200 to 400 ft. would be needed if slope exceeds 1% to achieve 9 minutes of hydraulic residence time. [Minton])

4. Length of swale should not be less than 100 ft. (CASQA)

5. Width of swale determined by using Manning’s Equation, with design storm runoff rate, based on Manning’s n of 0.25. (CASQA)

6. The flow depth at the design treatment flow rate should not exceed two thirds of the height of grass or 4 inches, which ever is less. (CASQA)

7. Normally use trapezoidal cross section, but other configurations may be used. (CASQA)

8. Side slopes should be no steeper than 3:1. (H:V). (CASQA and COL)

1. Must be vegetated. (CASQA)

2. A thick vegetative cover is needed for proper functioning. (EPA 2002)

3. A design grass height of 6 inches is recommended. (CASQA)

4. May be planted with turf grass or bunch grasses, shrubs, and trees. SAS has list of grass species for use in swales. (SAS)

1. Install an underdrain on all swales (COL)

2. The longitudinal channel slope should not exceed 2.5%. (CASQA) 1 to 2% slope is recommended. (EPA 2002)

3. May be used on line both to treat stormwater and to convey flows larger than hydraulic design treatment flows. (CASQA)

4. Velocity for 10-year design storm should not exceed the maximum velocity for the vegetation selected (estimated at 8-10 ft/sec maximum for most grasses with a channel slope of < 5%). COL

• FSURMP would like to thank the Alameda Countywide Clean Water Program for development of the original design and content of this table.

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Stormwater Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program Table 1:•Design Criteria Guidance for Vegetated Swales and Detention Basins Treatment

Control Hydraulic Residence

Time/Drain Time

Sizing/Shape

Vegetation

Other

Extended detention

basin

Use a drawdown time of 48

hours in most areas of

California. (CASQA)

1. Will occupy typically 2 to 3 percent of the contributing drainage area, but need a relatively large continuous area. (EPA 2002)

2. Size to capture and treat 80% or more of annual runoff using either of permit’s hydraulic sizing design criteria (permit).

3. Length to width ratio of at least 1.5:1 where feasible. (CASQA)

4. Basin depths optimally range from 2 to 5 ft. (CASQA)

5. Grass stabilized side slopes should be no steeper than 3:1 (H:V); steeper slopes need slope stabilization.

1. Specify emergent wetland vegetation and non-wetland plants tolerant of inundation. SAS has list of plant species for use in detention basins and infiltration areas. (SAS).

2. To help mitigate warming at the outlet channel, provide shade around the channel at the pond outlet. (EPA 2002).

1. Design outlet to allow for complete drawdown of water quality volume in 72 hours; and no more than 50% of water quality volume should be drained in first 24 hours. (CASQA)

2. Outlet structure should be regulated by a gate valve or orifice plate. Use trash rack or acceptable method to prevent clogging. (CASQA)

3. Include energy dissipation in the inlet designs to reduce re-suspension of accumulated sediment. (CASQA)

4. Do not include a small, permanent pool of water because of potential mosquito breeding. (CASQA)

5. May be used on or offline; and will need appropriate sizing and freeboards to convey or bypass 25-year and larger storm events. (CASQA)

CASQA = California Stormwater Quality Association. 2003. Best Management Practice Handbook. New Development and Redevelopment COL = City of Livermore. Undated. Draft Grass Swale Design Guidance EPA 2002 = Post-Construction Stormwater Management in New Development & Redevelopment. Dry Extended Detention Pond. Grassed Swales. Minton = Minton, Gary. 2002. Stormwater Treatment. SAS = Bay Area Stormwater Management Agencies. Start at the Source. 1999

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V. OPERATION AND MAINTENANCE OF POST-CONSTRUCTION CONTROL REQUIREMENTS

Maintenance is recognized as a critical component of stormwater treatment BMP effectiveness and useful life. All owners/operators of developments subject to the stormwater requirements are required to operate and maintain their BMPs so that they continue to perform properly as designed over the life of the project, and that they minimize potential nuisances and public health impacts from vector breeding (e.g. mosquitoes). City staff will require you to enter into maintenance agreements and will require annual reporting of the post-construction controls that you incorporate into your project. See Appendix D for the Stormwater Treatment Measures Maintenance Agreement that the development owner will be required to enter into prior to final approval of the project building permits. The Stormwater Treatment Measures Maintenance Agreement will be signed by an authorized city representative and the property owner or authorized representative of the HOA or Special District. The applicant will need to have proof of recording from the County Assessor’s Office, prior to issuance of the building permit. For more information on operation and maintenance requirements, contact your City Planning staff representative. The Stormwater Treatment Measures Maintenance Agreement, inspection checklists, fact sheets and reporting forms) are provided within Appendix D of this packet.

VI. CEQA REQUIREMENTS The following table provides supplemental guidance to project applicants in completing the CEQA initial study checklist to better address urban runoff water considerations during project environmental review. Incorporating these revisions into the initial study analysis will assist to streamline both the local agency and Water Board’s review of the CEQA documentation. The CEQA Checklist Within the existing CEQA Guidelines framework, the following issues should be considered when determining levels of project impacts.

CEQA Guidelines Question Additional Issues to Address Stormwater

Quality Concerns Within the CEQA Initial Study Checklist

CHECKLIST CHAPTER IV: BIOLOGICAL RESOURCES

IV.b) Will the project have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations or by the California Department of Fish and Game or US Fish and Wildlife Service?

The evaluation of a project’s effect on sensitive natural communities should encompass aquatic and wetland habitats. Consider “aquatic and wetland habitat” as examples of sensitive habitat.

Any changes to sensitive habitats that favor the development of mosquitoes and other biting flies that may pose a threat to public health should also be evaluated as an adverse impact.

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CHECKLIST CHAPTER VIII: HYDROLOGY AND WATER QUALITY

VIII.a) Will the project violate any water quality standards or waste discharge requirements?

The evaluation of a project’s compliance with water quality standards should consider the project’s potential effect on water bodies on the Section 303(d) list4, as well as the potential for conflict with applicable surface or groundwater receiving water quality objectives or degradation of beneficial uses.

In addition, the Water Board staff has requested that the following potential water quality impacts not be overlooked during CEQA review:

• Seasonal creeks; • Stream crossing impacts; • Turbidity limitation for discharged water; • Whether increased runoff from increasing

impervious surface area will impact water ecology (along with storm drain capacity and flood control);

• Hydrograph modification; • Endangered species; • Off-site impacts to channels; and • Appropriateness of runoff mitigation

VIII.c) Would the project substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, in a manner which would result in substantial erosion or siltation on-or off-site?

Upon the completion, review and approval of the FSURMP Hydromdification Management Plan (HMP) by the Water Board, the FSURMP local agencies will consider whether to adopt a resulting threshold of significance for impacts resulting from increases in peak runoff flows and durations that can result in substantial off-site erosion that would be given to every project proponent. (Note: The FSURMP HMP was submitted to the Water Board for consideration of approval on April 14, 2006).

VIII.d) Will the project substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner which would result in flooding on- or off-site?

The evaluation of a project’s effect on drainage patterns should refer to the draft or final approved FSURMP Hydrograph Modification Management Plan (HMP), where and when applicable, to assess the significance of altering existing drainage patterns and to develop any mitigation measures. The evaluation of hydromodification effects should also consider any potential for streambed or bank erosion downstream from the project. (Note: The FSURMP HMP was submitted to the Water Board for consideration of approval on April 14, 2006).

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4 Available at: http://www.swrcb.ca.gov/rwqcb2/tmdlmain.htm




VIII.e) Will the project create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff?

The evaluation of a project’s potential to create or contribute runoff should consider whether the project meets the NPDES permit’s Group 1 or Group 2 criteria. The response to this question will indicate how stormwater requirements will be met. Applicants must address stormwater requirements in environmental documents for projects that meet Group 1 or Group 2 criteria.

VIII.f) Would the project otherwise substantially degrade water quality?

The evaluation of a project’s potential to degrade water quality should consider whether a project has the potential to result in a significant impact to surface water quality, marine, fresh, or wetland waters, or to groundwater quality. As with every category of environmental impact, effects must be considered both during and after construction. The evaluation of water quality impacts should include a description of how the project will comply with the requirements of the FSURMP NPDES permit and the State’s Construction General Permit. The description should also include a statement that the project should avoid creation of mosquito larval sources that would subsequently require chemical treatment to protect human and animal health.

Potentially effective mitigation under CEQA could help prevent water quality impacts.

VII. GUIDANCE FOR COMPLETING THE NEW AND REDEVELOPMENT POST CONSTRUCTION STORMWATER REQUIREMENTS APPLICATION

The application is included in Section I (pages 5-8) and is designed to collect the necessary information related to stormwater for your projects. Although portions of the application will be useful to project proponents early in the development planning process as guidance and encouragement for reducing impervious surfaces, the final information should be collected at the building permitting stage. The following guidance is provided to assist project proponents with completing the application.

Project Name: Provide name of owner/project proponent.

APN #: Provide Assessor’s Parcel Number of site.

Applicant Name: Provide full legal name of owner/project proponent.

Project Description: Provide a brief description of the project.

Project Location: On the first line, indicated the address of the proposed project site. If a street address is not available, provide other descriptors such that the site could be located. On the second line, indicate the watershed that the project is located in (main creek/river or Bay) and the immediate receiving water (tributary, creek, marsh, Bay).

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Item 1. Project Type. Indicate whether the project will be located on an undeveloped site (New Development) or at a site with existing development (Redevelopment).

Item 2. Project Use. Indicate whether the project is Residential, Commercial Industrial, Public, Road, Multi-use or Other per the definitions in the Cities’ zoning code, as appropriate. For mixed-use developments, select all applicable boxes. Public projects include institutional developments (e.g., governmental offices and public schools). Although often a subcategory of public projects, roads are listed separately due to their distinguishing characteristics.

If the project is a single-family residential home that is not part of a larger common plan of development, the project will be considered in compliance with the stormwater requirements, if appropriate pollutant source control and site design measures are implemented. This may include the use of landscaping to appropriately treat roof and house-associated impervious surface runoff.

Item 3. Project Size. The six subsections in this item provide a pathway for determining the total and percent increase or replacement of impervious surface area (see items d. and e., respectively). The amount of impervious surface at the site is essential to determining the applicability of Group 1 and Group 2 requirements for requiring and sizing stormwater treatment BMPs.

Item 4. Type of Pesticide Reduction Measures Used. City staff should check the appropriate boxes if educational materials (e.g., fact sheets or information on pest resistant plants is provided to the owner/project proponent--Education or if the pesticide-reduction related Conditions of Approval were placed on the project--Conditions of Approval. Some development projects may not have a landscaping component. In such cases “Doesn’t Apply” should be checked.

Item 5. Types of Stormwater Controls Used. This item provides three selections: treatment measures, source control measures and site design measures. These items refer to categories of specific stormwater control measures found on page 3 of the application. Permittees and/or project proponents can indicate on that page what specific stormwater control measures will be incorporated into the project. If the control(s) fall under the headings of stormwater treatment, source controls and/or site design, the requisite boxes should also be checked on page 2 of the application. Single-family residential homes not part of a common development should only consider or incorporate source control and site design measures. For additional information on stormwater treatment measures, see Section IV. For additional information on source controls and site design measures, see Section III. Additional resources include BASMAA’s Start at the Source (1999) available at the Cities’ websites and the California Stormwater BMP Handbooks, located on the web at www.cabmphandbooks.com.

Item 6. Hydromodification Management Plan (HMP) Applicability. For certain areas in the City of Fairfield, the project may need to meet additional requirements associated with the Hydromodification Management Plan. In subsection 6.a. of this item, indicate whether the project discharges directly to a municipal storm drain system, a creek or Suisun Bay.

Under subsection 6.b, indicate whether the project is exempt. This definition will be provided by City of Fairfield’s stormwater staff. Currently all projects in Suisun City would be exempt. If “Yes,” the project is exempt from HMP. If “No,” the requirements of the HMP will need to be met.

Item 8. Specific Stormwater Control Measures. The list on page 3 of the application provides a method to indicate the stormwater treatment, source control and site design

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measures that will be incorporated into the project. Boxes are provided to indicate the number of systems installed, in the case of stormwater treatment BMPs.

Item 9. Treatment Control Details. The table provided on Page 4 of the application should be used to enter additional details regarding treatment control BMPs installed and maintained for the project. Information includes an identifier for each BMP installed and the sizing method used (Section IV).

VIII. ADDITIONAL RESOURCES AND CONTACTS Contacts for More Information

City of Fairfield: (707) 428-7485

City of Suisun City: (707) 421-7340

Fairfield-Suisun Urban Runoff Management Program (FSURMP): (707) 429-8930

San Francisco Bay Regional Water Quality Control Board: (510) 622-2300

United States Army Corp of Engineers (Section 404 Permit) (415) 977-8461

California Department of Fish and Game (Streambed Alteration Agreement (Section 1603)) (707) 944-5520

Resources

1) Bay Area Stormwater Management Agencies Association, Start at the Source, 1999. http://www.basmaa.org/resources/files/Start%20at%20the%20Source%20-%20Design%20Guidance%20Manual%20for%20Stormwater%20Quality%20Protection.pdf

2) Bay Area Stormwater Management Agencies Association, Using Site Design Techniques to Meet Development Requirements, 2003. http://www.basmaa.org/resources/files/Using%20Site%20Design%20Techniques.pdf.

3) California BMP Handbooks (New Development and Redevelopment; Construction) January 2003. http://www.cabmphandbooks.com/

4) FSURMP, “Guidance for Design of Detention Basins For Water Quality Improvements.” April 1996.

5) FSURMP, “Landscape Maintenance Techniques for Pest Reduction.”

6) Fairfield-Suisun Urban Runoff Management Program, Order No. R2-2003-0034, NPDES Permit No. CAS612005.

Additional References CASQA, California Best Management Practice Handbook New Development and

Redevelopment, Appendix D: “Unit Basin Volume for 80% Capture,” May 2003.

Solano County Water Agency. Hydrology Manual. June 1999.

Water Environment Federation (WEF) Manual of Practice No. 23/American Society of Civil Engineers (ASCE) Manual and Report of Engineering Practice No. 87, 1998. Urban Runoff Quality Management.

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http://www.basmaa.org/resources/files/Using%20Site%20Design%20Techniques.pdf

http://www.cabmphandbooks.com/

Stormwater Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program Glossary of Terms Definitions Construction General Permit – Dischargers whose projects disturb one (1) or more acres of soil or whose projects disturb less than one (1) acre but are part of a larger common plan of development that in total disturbs one (1) or more acres, are required to obtain coverage under the General Permit for Discharges of Stormwater Associated with Construction Activity (Construction General Permit, 99-08-DWQ). Construction activity subject to this permit includes clearing, grading and disturbances to the ground such as stockpiling, or excavation, but does not include regular maintenance activities performed to restore the original line, grade, or capacity of the facility. For more information see: http://www.swrcb.ca.gov/stormwtr/construction.html Deemed Complete – The City reviews development applications within 30 days of submittal to determine whether all the required information has been provided and the application can be “deemed complete” and accepted. If the application submittal is incomplete, staff sends a letter to the applicant indicating that the application is “deemed incomplete” and lists the items needed to complete the application. If the Planning Division’s written determination is not made within 30 days after receipt of the application, under State Law, it is deemed “complete” and staff proceeds with processing the application. Discharge – The discharge, addition, placement, deposit, release or dumping of any pollutant or combination of pollutants to surface waters from any point source. This definition includes, but is not limited to, additions of pollutants into waters from surface runoff and discharges through pipes, sewers, channels, or other conveyances owned by a state, municipality or other person which do not lead to treatment works. Impervious Surface – Constructed or modified surface that can not effectively infiltrate rainfall. Impervious surface includes but is not limited to building rooftops, pavement, sidewalks, and driveways where such surfaces are not construction with pervious materials. Major development or redevelopment project – A project that creates, adds, or replaces one acre (43,560 square feet) or more of impervious surface for project applications that are deemed complete on or after April 16, 2005. For those project applications that are deemed complete on or after October 16, 2006, a major development or redevelopment project means a project that creates, adds or replaces 10, 000 square feet or more of impervious surface. Project with Significant Pollution Potential – Any project determined by the District to be likely to have sources of pollutants on-site and/or to contribute pollutants to stormwater after project completion, based on a review of the proposed uses of or activities planned for the site. Pervious surface – Any constructed or modified surface that allows water to penetrate the surface. Pervious surfaces include but are not limited to porous concrete, gravel and permeable interlocking concrete. Source Control BMP – Any schedules of activities, prohibitions of practices, maintenance procedures, managerial practices or operational practices that aim to prevent stormwater pollution by reducing the potential for contamination at the source of pollution. Treatment Control BMP – Any engineered system designed to remove pollutants by simple gravity settling of particulate pollutants, filtration, biological uptake, media adsorption or any other physical, biological, or chemical process.

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Stormwater Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program Abbreviations and Acronyms

APN Assessor’s Parcel Number ASCE American Society of Civil Engineers BASMAA Bay Area Stormwater Management Agencies Association BMPs Best Management Practices CASQA California Stormwater Quality Association CCRs Conditions, Covenants and Restrictions CEQA California Environmental Quality Act City City of Fairfield and/or Suisun City COL City of Livermore CUPA Certified Unified Program Agency District Fairfield-Suisun Sewer District EPA Environmental Protection Agency FSSD Fairfield-Suisun Sewer District FSURMP Fairfield-Suisun Urban Runoff Management Program HMP Hydrograph Modification Management Plan IPM Integrated Pest Management NOI Notice of Intent NPDES National Pollutant Discharge Elimination System O&M Operations and Maintenance SAS Start at the Source SCMAD Solano County Mosquito Abatement District SWPPP Stormwater Pollution Prevention Plan SWRCB State Water Resources Control Board TMDL Total Maximum Daily Load URQM Urban Runoff Quality Management Water Board San Francisco Bay Regional Water Quality Control Board WEF Water Environment Federation WDRs Waste Discharge Requirements

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Storm Water Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program

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Appendix A

Design Drawing for Common Source Controls • SW-1: Car Wash Exit • SW-2: Loading Dock • SW-3: Business/Commercial

Trash Enclosure • SW-4: Fueling Area

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Appendix B

Storm Water Pollution Control Measures List

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Storm Water Pollution Control Measures List

INTRODUCTION

The following list contains measures to control sources of storm water pollutants associated with the post-construction phase of new development and redevelopment projects. Each identified source of pollutants may have one or more appropriate control measures. The model list is intended to be a menu from which municipalities may select appropriate measures to apply to specific projects. A. General

1) The project will incorporate site design measures for reducing water quality impacts of the project, in compliance with the [City] NPDES stormwater permit Provision C.3. requirements. Guidance on approved site design measures is available from the [Public Works/Planning Department]. Final approval for site design measures must be obtained from the [Planning/Community Development/Public Works Department].

2) Significant natural features and resources on site such as undisturbed forest area, setbacks, easements, trees, steep slopes, erosive soils, wetlands or riparian areas shall be identified within the area to be developed and protected during construction and during future use of the site.

3) Site layout shall conform to natural landforms on-site. Buildings shall be located to utilize natural drainage systems as much as possible and avoid unnecessary disturbance of vegetation and soils. Development on unstable or easily erodible soils shall be avoided due to their greater erosion potential.

4) Directly connected impervious surfaces shall be minimized. Runoff from impervious areas shall be channeled to pervious areas (e.g., park strips, vegetated planters) where possible prior to discharge to the storm drain.

5) Site permeability shall be maximized by clustering buildings, reducing building footprints, minimizing impervious surfaces, and paving with permeable materials where feasible.

6) The project shall cluster structures and incorporate smaller lot sizes where feasible to reduce overall impervious surface coverage and provide more undisturbed open space, for protection of water resources.

7) The amount of open space on the site shall be maximized and the open space area maintained in a natural manner.

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8) Undisturbed natural areas such as conservation areas and stream buffers shall be utilized to treat and control stormwater runoff from other areas of the site with proper design.

9) The project shall utilize infiltration measures to reduce stormwater discharge to the greatest extent feasible.

10) The applicant shall minimize increases in stormwater flow and volume resulting from the development project to protect creeks and waterways from flooding and erosion impacts.

B. Illegal Dumping to Storm Drain Inlets and Waterways

On-site storm drain inlets shall be clearly marked with the words “No Dumping! Flows to Creek,” or equivalent.

C. Interior Floor Drains

Interior floor drains shall be plumbed to the sanitary sewer system and shall not be connected to storm drains.

D. Parking Garages

Interior level parking garage floor drains shall be connected to a properly sized oil-water separator prior to discharging to the sanitary sewer system. The applicant shall contact the Fairfield-Suisun Sewer District for specific connection and discharge requirements.

E. Pesticide/Fertilizer Application

1) Landscaping shall be designed to minimize irrigation and runoff, promote surface infiltration where appropriate, and minimize the use of fertilizers and pesticides that can contribute to storm water pollution.

2) Structures shall be designed to discourage the occurrence and entry of pests into

buildings, and thus minimize the need for pesticides. For example, dumpster areas should be located away from occupied buildings, and building foundation vents shall be covered with screens.

3) If a landscaping plan is required as part of a development project application, the

plan shall meet the following conditions related to reduction of pesticide use on the project site:

a. Where feasible, landscaping shall be designed and operated to treat storm

water runoff by incorporating elements that collect, detain, and allow infiltration of runoff. In areas that provide detention of water, plants that

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are tolerant of saturated soil conditions and prolonged exposure to water shall be specified.

b. Plant materials selected shall be appropriate to site specific characteristics

such as soil type, topography, climate, amount and timing of sunlight, prevailing winds, rainfall, air movement, patterns of land use, ecological consistency and plant interactions to ensure successful establishment.

c. Existing native trees, shrubs, and ground cover shall be retained and

incorporated into the landscape plan to the maximum extent practicable. d. Proper maintenance of landscaping, with minimal pesticide use, shall be

the responsibility of the property owner. e. Integrated Pest Management (IPM) principles and techniques shall be

encouraged as part of the landscaping design to the maximum extent practicable. Examples of IPM principles and techniques include:

1. Select plants that are well adapted to soil conditions at the site.

2. Select plants that are well adapted to sun and shade conditions at the site. In making these selections, consider future conditions when plants reach maturity, as well as seasonal changes.

3. Provide irrigation appropriate to the water requirements of the selected plants.

4. Select pest- and disease-resistant plants.

5. Plant a diversity of species to prevent a potential pest infestation from affecting the entire landscaping plan.

6. Use insect friendly plants in the landscaping to attract and keep beneficial insects.

F. Pool, Spa, and Fountain Discharges

1) Pool (including swimming pools, hot tubs, spas and fountains) discharge drains shall not be connected directly to the storm drain or sanitary sewer system, unless the connection is specifically approved by the Fairfield-Suisun Sewer District. Public pool discharge drains may be connected to the sanitary sewer system, in accordance with applicable local requirements of the Fairfield-Suisun Sewer District.

When draining is necessary, a hose or other temporary system shall be directed into a sanitary sewer clean out. The clean out shall be installed in a readily accessible area (i.e. within 10 feet of the pool/spa/fountain).

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G. Food Service Equipment Cleaning

Food service facilities (including restaurants and grocery stores) shall have a sink or other floor mat, container, and equipment cleaning area that is connected to a grease interceptor prior to discharging to the sanitary sewer system. The cleaning area shall be large enough to clean the largest mat or piece of equipment to be cleaned. The cleaning area shall be indoors or in a roofed area outdoors; both areas must be plumbed to the grease interceptor and the sanitary sewer. Outdoor cleaning areas shall be designed to prevent storm water run-on from entering the sanitary sewer and to prevent storm water run-off from carrying pollutants to the storm drain. Signs shall be posted indicating that all food service equipment washing activities shall be conducted in this area. Regular maintenance and cleaning of the grease interceptor is required and may be subject to periodic inspections conducted by municipal staff.

H. Refuse Areas

1) New buildings such as food service facilities and/or multi-family residential complexes shall provide a roofed and enclosed area for dumpsters and recycling containers. The area shall be designed to prevent water run-on to the area and runoff from the area and to contain litter and trash, so that it is not dispersed by the wind or runoff during waste removal. See Appendix A, drawing SW-3 for details.

2) Runoff from trash enclosures, recycling areas, and/or food compactor enclosures,

or similar facilities shall not discharge to the storm drain system. Trash enclosure areas shall be designed to avoid run-on to the trash enclosure area. If any drains are installed in or beneath dumpsters, compactors, and tallow bin areas serving food service facilities, the drains shall be connected to a properly sized grease removal device and/or treatment devices prior to discharging to the sanitary sewer.

I. Outdoor Process Activities/Equipment1

1) Process activities shall be performed either indoors or in roofed outdoor areas. If performed outdoors, the area shall be designed to prevent run-on to and runoff from the area with process activities. Examples of appropriate design to prevent run-on and runoff include using a berm or grade break.

2) Process equipment areas shall drain to the sanitary sewer system. The applicant shall contact the Fairfield-Suisun Sewer District for specific connection and discharge requirements.

1 Examples of businesses that may have outdoor process activities and equipment include machine shops and auto repair shops, and industries that have pretreatment facilities.

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J. Outdoor Equipment/Materials Storage

1) All outdoor equipment and materials storage areas shall be covered and bermed, or shall be designed to limit the potential for runoff to contact pollutants. Storage or maintenance/repair activities shall occur only on paved and contained areas.

2) Storage areas containing non-hazardous liquids shall be covered by a roof and contained by berms, dikes, liners, vaults, or similar spill containment devices.

3) All on-site hazardous materials and wastes, as defined by the California Public Health Code and the local Certified Unified Program Agency (CUPA) must be used and managed in compliance with the applicable CUPA program regulations and the facility hazardous materials management plan approved by the CUPA authority. Please contact Solano County’s Environmental Health Division at 707-421-6765 for further details.

K. Vehicle/Equipment Cleaning

1) Wastewater from vehicle and equipment washing operations shall not be discharged to the storm drain system. Any wastewater discharges to the sanitary sewer are subject to approval by the Fairfield-Suisun Sewer District.

2) Commercial/industrial facilities having vehicle/equipment cleaning needs and new residential complexes of 25 units or greater shall either provide a roofed, bermed area for washing activities or discourage vehicle/equipment washing by removing hose bibs (faucets) and installing signs prohibiting such uses. Vehicle/equipment washing areas shall be paved, designed to prevent run-on to or runoff from the area, and plumbed to drain to a sand and grit separator and then to the sanitary sewer. A sign shall be posted indicating the location and allowed uses in the designated wash area. The applicant shall contact the Fairfield-Suisun Sewer District for specific connection and discharge requirements.

3) Commercial car wash facilities shall be designed and operated such that no runoff from the facility is discharged to the storm drain system. Wastewater from the facility shall discharge to the sanitary sewer or a wastewater reclamation system shall be installed and the wastewater reused with no discharges to the storm drain. The applicant shall contact the Fairfield-Suisun Sewer District for specific connection and discharge requirements. Please see Appendix A, drawing SW-1 for details.

L. Vehicle/Equipment Repair and Maintenance

1) Vehicle/equipment repair and maintenance shall be performed in a designated area indoors, or if such services must be performed outdoors, in an area designed to prevent the run-on and runoff of storm water.

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2) Secondary containment shall be provided for exterior work areas where motor oil, brake fluid, gasoline, diesel fuel, radiator fluid, acid-containing batteries or other hazardous materials or hazardous wastes are used or stored. Drains shall not be installed within the secondary containment areas.

3) Vehicle service facilities shall not contain floor drains unless the floor drains are connected to wastewater pretreatment systems prior to discharge to the sanitary sewer, for which an industrial waste discharge permit has been obtained. The applicant shall contact the Fairfield-Suisun Sewer District for specific connection and discharge requirements.

M. Fuel Dispensing Areas

1) Fueling areas2 shall have impermeable surfaces (i.e., portland cement concrete or equivalent smooth impervious surface) that are: a) graded at the minimum slope necessary to prevent ponding; and b) separated from the rest of the site by a grade break that prevents run-on of storm water to the maximum extent practicable.

2) The fueling area must be roofed and the roof’s minimum dimensions must be equal to or greater than the area within the grade break or fuel dispensing area, as defined below3. The canopy shall not drain onto the fueling area. See Appendix A, drawing SW-4 for details.

N. Loading Docks

1) Loading docks shall be covered and/or graded to minimize run-on to and runoff from the loading area. Roof downspouts shall be positioned to direct storm water away from the loading area. Water from loading dock areas shall be plumbed as depicted in Appendix A, drawing SW-2. The applicant shall contact the Fairfield-Suisun Sewer District for specific connection and discharge requirements.

2) Loading dock areas shall be equipped with a spill control valve or equivalent device, which shall be kept closed during periods of operation, subject to approval by the Fairfield-Suisun Sewer District.

3) Door skirts between the trailers and the building shall be installed to prevent exposure of loading activities to rain, unless one of the following conditions apply: the loading dock is covered, or the applicant demonstrates that rainfall will not result in an untreated discharge to the storm drain system.

2 The fueling area shall be defined as the area extending a minimum of 6.5 feet from the corner of each fuel dispenser or the length at which the hose and nozzle assembly may be operated plus a minimum of one foot, whichever is greater. 3 The fueling area shall be defined as the area extending a minimum of 6.5 feet from the corner of each fuel dispenser or the length at which the hose and nozzle assembly may be operated plus a minimum of one foot, whichever is greater.

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O. Fire Sprinkler Test Water

Provisions shall be made in the project design and construction to allow for the discharge of fire sprinkler test water to the sanitary sewer or to a landscaped area.

P. Miscellaneous Drain or Wash Water

1) Boiler drain lines shall be directly or indirectly connected to the sanitary sewer system and may not discharge to the storm drain system.

2) For small air conditioning units, air conditioning condensate should be directed to landscaped areas as a minimum BMP. For large air conditioning units, in new developments or significant redevelopments, the preferred alternatives are for condensate lines to be directed to landscaped areas, or alternatively connected to the sanitary sewer system after obtaining permission from the Fairfield-Suisun Sewer District. As with smaller units, any anti-algal, descaling agents or other byproducts must be properly disposed of at an appropriately permitted disposal facility. Any air conditioning condensate that is discharged to land without flowing to a storm drain may be subject to the requirements of the State Water Resources Control Board’s (SWRCB) Statewide General Waste Discharge Requirements (WDRs) for Discharges to Land with a Low Threat to Water Quality.

3) Roof drains shall discharge and drain away from the building foundation to an unpaved area wherever practicable.

4) Roof top equipment including that producing air conditioning condensate shall drain to the sanitary sewer or be covered and have no discharge to the storm drain. The applicant shall contact the Fairfield-Suisun Sewer District for specific connection and discharge requirements.

5) An appropriately equipped facility that drains to the sanitary sewer must be provided for washing and/or steam cleaning activities. Sanitary connections are subject to the review, approval and conditions of the Fairfield-Suisun Sewer District for receiving the discharge. These conditions shall be required for automotive related businesses.

Q. Streets

1) Where density, topography, soils, slope and safety issues permit, vegetated open channels or other landscape measures shall be used in the street right of way to convey and treat stormwater runoff from roadways.

2) Sidewalks shall be sloped to drain to adjacent vegetated park strips.

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R. Parking Lots

1) Where feasible, parking lots and other impervious areas shall be designed to drain stormwater runoff to vegetated drainage swales, filter strips, and/or other treatment devices that can be integrated into required landscaping areas and traffic islands prior to discharge into storm drain systems.

2) The amount of impervious area associated with parking lots shall be minimized by providing compact car spaces, reducing stall dimensions, incorporating efficient parking lanes, and using permeable pavement in overflow parking areas where feasible.

3) Curb cuts (one every 10 feet), tire stops, or other means shall be provided to protect landscaped areas and allow maximum flow of stormwater into landscaped areas.

4) The use of permeable paving for parking and driveway surfaces is encouraged, to reduce runoff from the site. Such paving should meet fire department requirements and be structurally appropriate for the location.

S. Landscaping

1) Projects shall be designed to direct stormwater runoff into landscaping or natural vegetation where feasible.

2) Large landscaped areas shall be designed to collect and infiltrate stormwater where feasible. Overflow drains shall be placed so that landscaped areas can store runoff and drain at capacity. Such collection areas shall be designed and maintained to meet vector control requirements.

3) Where possible, runoff from impervious areas such as rooftops, roadways and parking lots shall be directed to pervious areas, open channels or vegetated areas prior to discharge to the storm drain system.

T. Riparian Areas

1) Naturally vegetated buffers shall be delineated and preserved along perennial streams, rivers, lakes and wetlands.

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Appendix C

Storm Water Treatment Requirement Worksheets

I. Initial Data Needs II. FSURMP Simplified Method for Sizing Flow-based Treatment Measures III. FSURMP Simplified Method for Sizing Volume-based Treatment

Measures

Attachment 1.0: Worksheets for Using Other Options Allowed in FSURMP Permit to Size Controls

Attachment 2.0: Example Worksheets for Determining Treatment Amounts: Village Apartments

Attachment 3.0: Example Calculations for Sizing a Vegetated Swale: Village Apartments (Flow-based Control)

Attachment 4.0: Example Calculations for Sizing a Detention Basin: Village Apartments (Volume-based Control) (To be developed)

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Fairfield-Suisun Urban Runoff Management Program

Storm Water Treatment Requirements Worksheets

NOTE: To determine whether your project must meet these treatment requirements, please refer

to the Storm Water New and Redevelopment Requirement Applicability Flow Chart on page 5 of the Project Applicant Package.

I. INITIAL DATA NEEDS I.A. Type of Treatment Measure Proposed for Project 1. If the treatment measure (or part of a series of measures) operate based on continuous flow of

runoff through the device (see Table C.1 for examples), continue to Section II.—Sizing for Flow-Based Treatment Controls on page WS-3.

2. If the treatment measure (or part of a series of measures) operate based on the volume of

water treated (i.e., detains an amount of runoff for a certain amount of time to allow solids and pollutants to settle to the bottom) (see Table C.1 for examples), continue to Section III.—Sizing for Volume-Based Treatment Controls on page WS-5.

Table C.1: Examples of Flow-based and Volume-based Controls Flow-based Controls Volume-based Controls Vegetated swales Extended detention basins (dry) Vegetated buffer strips Wet ponds Media filters Infiltration trenches1

Hydrodynamic separators Infiltration basins1 Wet vaults Bioretention areas Pop-up drainage emitters Constructed wetlands Other proprietary treatment devices Dry well Blue or green roofs I.B. Selection of Runoff Coefficients for Design Both the volume-based and flow-based sizing methods require estimation of the runoff coefficient or “C-factor”) for the completed project site or area draining to the BMP. Coefficients can be estimated based on the type of runoff surface or on the land use of the area, as illustrated in the Tables C.2a and C.2b on the following page. If the drainage area contains a mix of different surfaces or land uses, the average runoff coefficient for design should be calculated on a area-weighted basis. It is generally more accurate to compute an area-weighted runoff coefficient based on the surfaces in the drainage area (Table C.2a), if possible, than to assume a composite coefficient such as those in Table C.2b, especially for small drainage areas. 1 Note: Infiltration basins and trenches are not promoted in the Cities of Fairfield and Suisun City due to local conditions related to soils type and groundwater levels.

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Table C.2a – Estimated Runoff Coefficients for Various Surfaces

During Small Storms (BASMAA, 2003)

Surface Runoff Coefficient (C Factor)

Concrete 0.80 Asphalt 0.70 Pervious Concrete 0.60 Cobbles 0.60 Pervious Asphalt 0.55 Natural Stone (without grout) 0.25 Turf Block 0.15 Brick (without grout) 0.13 Unit Pavers on Sand 0.10 Crushed Aggregate 0.10 Grass 0.10 Roofs (from WEF/ASCE, 1992) 0.75

Notes: The above C-factors were estimated by selecting the lower range of the best available C-factor for each paving surface. These C-factors are only appropriate for small storm treatment BMP design, and should not be used for flood control sizing. Where available, locally developed small storm C-factors for various surfaces should be used.

Table C.2b – Estimated Composite Runoff Coefficients for

Small Storms by Land Use (WEF/ASCE, 2003)

Description of Area Runoff Coefficient (C Factor)

Business: Neighborhood Downtown

0.50 0.70

Residential: Single Family Multi-unit, detached Apartment Multi-unit, attached

0.30 0.40 0.50 0.60

Industrial: Light Heavy

0.50 0.60

Parks, cemeteries 0.10 Playgrounds 0.20 Unimproved 0.10

Notes: The above C-factors were estimated by selecting the lower range of the runoff coefficients listed for various land uses in WEF/ASCE, 1992. Where available, locally developed small storm C-factors for various land uses should be applied.

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II. FSURMP Simplified Method for Sizing Flow-Based Treatment Measures The FSURMP permit allows three methods for sizing flow-based treatment measures—the Factored Flood Flow Method (10% of the 50-year peak rainfall intensity); the California Best Management Practices2 (BMP) Handbook Method (flow produced by a rain event equal to at least 2 times the 85th percentile hourly rainfall intensity); or the Uniform Intensity Method (flow produced by a rain event equal to 0.2 inches/hour). FSURMP recommends the Uniform Intensity Method for sizing of flow-based controls as its preferred method. Applicants are allowed to use one of the other options if they provide extra documentation (and a fee) for the additional review required (please see Attachment 1.0 for directions for using alternative options allowed within the FSURMP permit). Uniform Intensity Approach

This method uses the rational method equation: Q=CIA

where: Q is the flow in cubic feet per second (cfs),

C is the runoff coefficient, I is the design intensity (in/hr), and A is the drainage area for the BMP (acres)

1. Determine the drainage area for the BMP, acres: A = _____________ 2. Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”,

using Table C.2a or C.2b (see page WS-2): It is more accurate to compute an area-weighted “C-factor” based on the surfaces in the drainage area (Table C.2a), if possible, than to assume a composite land use “C-factor” such as those in Table C.2b, especially for small drainage areas. For an example, please see the Breezewood project example worksheets (Attachment 2.0). The weighted-average can be found using the following equation:

C = Σ(Runoff Coefficient * Area)surface

Σ(Area) surface

C = ___________________

2 For the purpose of this worksheet, a stormwater best management practice or BMP, is the same as a stormwater treatment measure or device.

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3. Determine the Design flow (Q) using Q = CIA Use a design intensity of 0.2 in/hr, where C is the runoff coefficient, I is the design intensity, and A is the drainage area for the BMP (acres). Q = C*I*A Q = (Step 2) * (0.2 in/hr) * (Step 1) Q = __________cfs 3

The number above, Q, provides the amount of flow (in cubic feet per second) that your treatment control will need to be sized to handle to meet the storm water requirements. Additional calculations are necessary to provide the actual dimensions of your selected treatment control, and these will depend on the treatment control that you choose. For example calculations to size a vegetated swale, please see Appendix C, Attachment 3 (page C.3-1).

3 No conversion factor for correct units is needed for the rational method because 1 acre-in/hr * 43,560 ft2/acre *1ft/12 in * (1hr/3600 sec.) = 1 ft3/ sec or cfs.

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III. FSURMP Simplified Method for Sizing Volume-Based Controls The FSURMP permit allows two methods for sizing volume-based controls—the Urban Runoff Quality Management method (URQM Method) or the California BMP Handbook Method. FSURMP has developed a preferred, simplified method from these two to conduct sizing of volume-based controls. The simplified method is based on the California BMP Handbook method and includes several assumptions and uses parameters specific to the Fairfield and Suisun City areas. Applicants are allowed to use the other options allowed in the permit only if they provide extra documentation (and a fee) for the additional review required (please see Attachment 1.0 for directions for using alternative options allowed within the FSURMP permit). Simplified California BMP Handbook Method The simplified method utilizes the California BMP Handbook method, adapted based on local conditions, and the Sacramento 5 ESE rain gauge curves. The equation that will be used to size the BMP is:

BMP Volume = Correction Factor * Unit Storage* Drainage Area to the BMP

1. Determine the drainage area for the BMP in square feet: A = ______________ft2. 2. Determine the mean annual rainfall at the site to determine the correction factor.

a. Locate the project site on Figure 1 (page C-8). Determine the mean annual rainfall at the location of the project: _____ inches (Each line on Figure 1, called a rainfall isopleth, indicates locations where the same amount of rainfall falls on average each year (e.g., the isopleth marked 24 indicates that areas crossed by this line average 24 inches of rainfall per year). If the project location is between two lines, estimate the mean annual rainfall depending on the location of the site—your estimate should be between 18 and 30 inches.)

b. The Sacramento 5 ESE has been determined to be the most suitable rain gauge for this

comparison. Its mean annual rainfall is 19.1 inches. Determine the correction factor for the rainfall at the site using the information from Step 2.a., and the Sacramento 5 ESE rain gauge.

Correction Factor = mean annual rainfall at the site (from Step 2.a.)/19.1 inches Correction Factor: ____________

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3. Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”, using Table C.2a or C.2b:

It is more accurate to compute an area-weighted “C-factor” based on the surfaces in the drainage area (Table C.2a), if possible, than to assume a composite “C-factor” such as those in Table C.2b, especially for small drainage areas. For an example, please see the Breezewood project example worksheets (Attachment 2.0). The weighted-average can be found using the following equation:


Σ(Area) surface

C = ___________________

4. Find the unit storage volume for capture of 80% of annual runoff (inches)—assuming 48-hr drawdown (i.e., the time needed for the BMP to completely drain, as designed). Using the runoff coefficient value from Step 3 above and Table C.3 below, obtain the unit storage volume. ___________________(inches)

Table C.3: Unit Storage Volume for 80% Capture4 (assuming Sacramento 5 ESE Rain Gauge, 48-hr Drawdown)

Runoff Coefficient (C)

Unit Basin Storage for 80% Capture (inch)

0.25 0.18 0.30 0.22 0.35 0.26 0.40 0.29 0.45 0.33 0.50 0.37 0.55 0.40 0.60 0.44 0.65 0.47 0.70 0.51 0.75 0.55 0.80 0.58 0.85 0.62 0.90 0.66 0.95 0.69 1.00 0.73

4 Source: CASQA, California Best Management Practice Handbook New Development and Redevelopment, Appendix D: “Unit Basin Volume for 80% Capture,” January 2003.

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5. Size the BMP, using the following equation: BMP Volume = Correction Factor * Unit Storage Volume* Drainage Area to the BMP BMP Volume = (Step 2.b.) * (Step 4 (inches)) * (Step 1 (ft2)) * 1 foot/12 inches BMP Volume = _____ ft3

The volume above is the amount of water (in cubic feet) that your treatment control will need to treat to meet the storm water requirements. Additional calculations are necessary to provide the actual dimensions of your selected treatment control, and these will depend on the treatment control that you choose. For example calculations to size an extended detention basin, please see Appendix C, Attachment 4 (page C.4-1).

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Note: This figure has been adapted from the Solano County Water Agency’s Hydrology Manual (1999).

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ATTACHMENT 1.0

WORKSHEETS FOR USING OTHER OPTIONS ALLOWED IN FSURMP PERMIT TO SIZE CONTROLS

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Attachment 1A. Using Alternate Means of Sizing for Flow-based Treatment Controls. There are three methods of calculating Flow-based Treatment Controls from which to choose as outlined in Provision C.3.d of the FSURMP permit. The Uniform Intensity Approach can be found in Section II., page C-3 of the main section of Appendix C. Section A describes the Factored Flow Approach and Section B describes the California BMP Handbook Approach. Section A.—Sizing Flow-Based Treatment Controls based on the Factor Flow Approach This method uses the rational method equation to determine the design flow, using a design intensity that is 10 % of the 50-year peak intensity found on the local intensity-duration-frequency (IDF) curve:

Q=CIA where Q is the flow in cubic feet per second (cfs), C is the watershed runoff coefficient, I is the design intensity (in/hr), and A is the drainage area for the BMP (acres)

1. Determine the drainage area for the BMP in acres: A = ______________ 2. Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”,

using Table C.2a or C.2b (page WS-2): It is more accurate to compute an area-weighted “C-factor” based on the surfaces in the drainage area (Table C.2a), if possible, than to assume a composite “C-factor” such as those in Table C.2b, especially for small drainage areas. For an example, please see the Breezewood project example worksheets (Attachment 2.0). The weighted-average can be found using the following equation:


Σ(Area) surface

C = ___________________

3. Find the time of concentration for the site (equal to the travel time from the most remote portion of area that drains into the water quality basin). (Obtain guidance from engineering department; often calculated using Manning’s Equation).

Time of overland flow + time in drainage pipe = time of concentration = ______min

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4. Find a local Intensity Duration Frequency (IDF) curve used for storm drainage design. Using the time of concentration (Step 3) as the duration and a 50-year return period event, determine the intensity (in/hr) from the IDF curve. _____ 5

5. The design intensity will be 10% of the 50-year intensity obtained from the IDF curve. I = (Step 4 * 0.10) I = ________ in/hr

6. Determine the flow in cubic feet per second, using: Q = CIA

Q = (Step 2)*(Step 5) * (Step 1) Q = _______________ cfs6

5 The City of Fairfield Standard Specifications (page 27) contains a table of rainfall intensity for the 15 year, 25 year, and 100 year storm. However, the permit requires that the 50-year rainfall intensity be used. Therefore, this table maybe used to determine the range and provide an initial estimate as to whether this approach may yield a smaller BMP size than another approach, but cannot be used for an actual calculation. Other resources for the Fairfield and Suisun City area were not readily available at the time these worksheets were developed. 6 No conversion factor for correct units is needed for the rational method because 1 acre-in/hr * 43,560 sq.ft/acre *1ft/12 in * (1hr/3600 sec.) = 1 ft3/ sec or cfs.

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Section B.—Sizing Flow-Based Treatment Controls Using the California BMP Handbook Flow Approach The 85th percentile hourly rainfall intensity for Sacramento 5 ESE Rain gauge is 0.095 in /hr. Therefore, per the FSURMP permit requirements, the design rainfall intensity (I) is twice the 85th percentile value or 0.19 in /hr. The design intensity of 0.19 in /hr for Sacramento 5 ESE is appropriate to use for the Fairfield and Suisun City areas, once a correction factor is applied (see Step 4 below). The intensity represents the rate of rainfall (a depth per hour) and needs to be converted to a flow of runoff from the drainage area to the BMP. The flow is calculated using the rational formula Q=CIA, where:

Q is the flow in cubic feet per second (cfs), C is the runoff coefficient of the drainage area to the BMP I is the design intensity (in/hr), and A is the drainage area for the BMP (acres)

1. Determine the drainage area for the BMP in acres: A = ______________ac. 2. Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”, using

Table C.2a or C.2b (page WS-2): It is more accurate to compute an area-weighted “C-factor” based on the surfaces in the drainage area (Table C.2a), if possible, than to assume a composite “C-factor” such as those in Table C.2b, especially for small drainage areas. For an example, please see the Breezewood project example worksheets (Attachment 2.0). The weighted-average can be found using the following equation:


Σ(Area) surface

C = ___________________

3. Determine the mean annual rainfall at the site to determine the correction factor.

a. Locate the project site on Figure 1 (page C-8). Determine the mean annual rainfall at the location of the project: _____inches (Each line on Figure 1, called a rainfall isopleth, indicates locations where the same amount of rainfall falls on average each year (e.g., the isopleth marked 24 indicates that areas crossed by this line average 24 inches of rainfall per year). If the project location is

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between two lines, estimate the mean annual rainfall depending on the location of the site—your estimate should be between 18 and 30 inches.)

b. The Sacramento 5 ESE has been determined to be the most suitable rain gauge for this

comparison. Its mean annual rainfall is 19.1 inches. Determine the correction factor for the rainfall at the site using the information from Step 3.a., and the Sacramento 5 ESE rain gauge.

Correction Factor = mean annual rainfall at the site (from Step 3.a.)/19.1 inches Correction Factor: ____________

4. Determine the corrected design rainfall intensity (I) for the site:

Design intensity (site) = Correction factor * Design rainfall intensity for Sacramento 5ESE

Design intensity (site) = (Step 3b) * 0.19 in/hr = ________________ in/hr

5. Determine the design flow (Q) using Q = CIA, and the corrected design intensity I.

Q = C*I*A Q = (Step 2) * (Step 4) * (Step 1)

Q = __________cfs 7

7 No conversion factor for correct units is needed for the rational method because 1 acre-in/hr * 43,560 sq.ft/acre *1ft/12 in * (1hr/3600 sec.) = 1 ft3/ sec or cfs.

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Attachment 1B. Using Alternate Means of Sizing for Volume-based Treatment Controls There are two methods of calculating Volume-based Treatment Controls as outlined in the FSURMP NPDES storm water permit from which to choose. The California BMP Handbook Approach can be found in Section III., page C-5, of the main section of Appendix C. Section A below describes the URQM Approach. Section A.—Sizing Volume-Based Treatment Controls based on the Urban Runoff Quality Management8, Approach (URQM Approach) The equations used in this method are:

Po=(a*Cw)* P6 Cw =0.858i3 – 0.78i2 + 0.774i + 0.04

Where Po = maximized detention storage volume based on the volume capture ratio as its basis

(watershed inches) a = regression constant from least-squares analysis (unit less) Cw = watershed runoff coefficient (unit less)

P6 = mean storm precipitation volume (watershed inches); i = watershed impervious ratio (range: 0-1) 1. Determine the drainage area for the BMP in square feet: A = ______________ ft2.

2. Determine the amount of impervious area draining to the BMP: ___________ ft2.

3. Determine the impervious ratio, i:

i = (percent imperviousness of drainage area for BMP)/100 OR i = amount of impervious area (ft2)/drainage area for the BMP (A) (ft2) i = __________________ (range will be from 0-1)

4. Determine the watershed runoff coefficient, Cw via the equation: Cw=0.858i3 – 0.78i2 + 0.774i + 0.04 where i is the watershed impervious ratio (range: 0-1) from Step 3. Cw= __________________________

5. Determine the mean annual rainfall at the site. Locate the project site on Figure 1 (page C-8).

Determine the mean annual rainfall at the location of the project: _____inches

8 (WEF Manual of Practice No. 23 and the ASCE Manual of Practice NO. 87 (1998) pages 175-178)

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P6 site

Event rainfall P6 SAC

(Each line on Figure 1, called a rainfall isopleth, indicates locations where the same amount of rainfall falls on average each year (e.g., the isopleth marked 24 indicates that areas crossed by this line average 24 inches of rainfall per year). If the project location is between two lines, estimate the mean annual rainfall depending on the location of the site—your estimate should be between 18 and 30 inches.) The mean storm event rainfall depth for the Sacramento 5 ESE is 0.55 inches. Sacramento’s Mean Annual Rainfall (in) is estimated to be 19.1 inches.

6. Find the mean storm rainfall depth in inches, called P6. Find P6 by assuming the ratio of the mean event rainfall (in) at the Sacramento 5 ESE (0.55 inches) to the mean annual rainfall at the site (in) will be proportional to that at the project site in Fairfield or Suisun City.

P6 site = __________watershed inches

7. Find a, the regression constant from least-squares analysis (unit less): a = 1.963 for a 48-hour

drain time and 1.582 for a 24-hour drain time. Recommendation: Design the measure to use a 48-hour drain time. a = ____________________

8. Determine the maximized detention storage volume based on the volume capture ratio

Po = (a*Cw) * P6 Po = (Step 7 * Step 4) * Step 6 Po = __________watershed inches

9. Determine the volume of the runoff to be treated from the drainage area to the BMP (i.e., the

BMP design volume) Design Volume = Po * A = (Step 8) * (Step 1) * 1 foot/12 inches Design Volume = __________ ft3

Event rainfall at site

Mean Annual Rainfall SAC Event rainfall P6 site

Mean Annual Rainfall site (from Figure 1) =

=

0.55 inches 19.1 inches

P6 site

(Step 5) =

0.55 inches * (Step 5) 19.1 inches

= =

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ATTACHMENT 2.0

EXAMPLE WORKSHEETS FOR DETERMINING TREATMENT AMOUNTS:

VILLAGE APARTMENTS

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Attachment 2.0 Example Site Calculations

Village Apartments The following examples are provided for illustrative purposes only and do not necessarily represent configuration or characteristics of any actual site. Sizing examples are provided for three separate scenarios, and illustrate both the FSURMP-preferred and alternative sizing methods available based on the FSURMP permit requirements. Assumptions1

• 5-acre (217,800 ft2) Low-Income Housing Apartment Complex • 81 residences with 1-acre (43,560 square feet) (20% of site) building coverage • Parking: 2-acres (87,120 square feet) (40% of site) of pavement and parking

Scenarios2 1. Entire Site – All Runoff Drains to One BMP

A. Sizing for Flow-Based Controls Using Uniform Intensity Method (Preferred) B. Sizing for Volume-Based Controls Using California BMP Handbook Method

(Preferred) C. Sizing for Flow-Based Controls Using California BMP Handbook Method D. Sizing for Volume-Based Controls Using URQM Method

2. Pavement – Pavement Drains to One BMP


(Preferred) 3. Rooftops and Walkways – Rooftop Runoff for Each Lot Drains to BMP


(Preferred)

1 These examples are provided for illustrative purposes only and do not address the benefits of incorporating site design techniques into the design. Site design techniques can be incorporated into project designs that will result in the need for smaller treatment control sizes. For more information, see BASMAA’s Using Site Design Techniques to Meet Development Standards for Stormwater Quality, May 2003, available on the City’s website. 2 The Factored Flow Approach for flow-based treatment controls is not illustrated herein because an adequate local IDF curve for the 50-year storm is not available at this time.

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Table of Results The following table summarizes the results of the calculations made on the following pages. The actual dimensions of the treatment control that you choose are specific to individual treatment control and site characteristics. For additional calculations to illustrate how to size the dimensions of a vegetated swale, see Attachment 3.0 (page C.3-1); and for an extended detention basin, see Attachment 4.0 of Appendix C (page C.4-1).

Example Flow-Based (cfs)

Volume-Based (cubic feet)

Comments

1. Entire Site—

A.B. Preferred Methods

0.47

7,496

Drains to one BMP

C.D. Alternative Methods 0.52 9,438

2. Pavement Areas 0.29 4,540 Drain to perimeter landscaping

3. Rooftops 0.15 2,356 Drain to landscaping adjacent to buildings

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Example 1A: Sizing for Flow-Based Controls Given: 5-acre (217,800 ft2) Low-Income Housing Apartment Complex

Parking: 2-acres (87,120 ft2) of pavement and parking 81 apartments with:

1-acre (43,560 ft2) square feet building coverage All runoff drains to flow-based BMP

Task: To determine the BMP flow required to effectively detain and treat storm water runoff

using the preferred Uniform Intensity Method. Step 1: Total Drainage Area to BMP = A = 5 acres Step 2: Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”,

using Table C.2a or C.2b (see page C-2) There are two ways to determine the runoff coefficient: 1) Using Table C.2a, the following assumptions can be made about the surfaces in the

drainage area:

Table C.2a – Estimated Runoff Coefficients for Various Surfaces During Small Storms (CDM, 2003)


Area of Surface (sq. ft.)

Concrete 0.80 0 Asphalt 0.70 87,120 Pervious Concrete 0.60 0 Cobbles 0.60 0 Pervious Asphalt 0.55 0 Natural Stone (without grout) 0.25 0 Turf Block 0.15 0 Brick (without grout) 0.13 0 Unit Pavers on Sand 0.10 0 Crushed Aggregate 0.10 0 Grass 0.10 87,120 Roofs 0.75 43,560

The weighted-average can be found using the following equation:


Σ(Area) surface

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C = (0.70 * 87,120) + (0.75 * 43,560) + (0.10 * 87,120) 217,800

= 0.47 2) Using Table C.2b, the site can be considered as an apartment complex, therefore the

runoff coefficient is 0.50.

Table C.2b – Estimated Composite Runoff Coefficients for Small Storms by Land Use (WEF/ASCE, 2003)



0.50 0.70


0.30 0.40 0.50 0.60


0.50 0.60


In comparison, the two values are similar, however it is more accurate to compute an area-weighted “C-factor” based on the surfaces in the drainage area (Table C.2a) rather than to use the more general “Apartment” land use designation estimate from Table C.2b. Therefore, a runoff coefficient of 0.47 will be used.

Step 3: Determine the Design flow (Q) using Q = CIA Use a design intensity of 0.2 in/hr in the Q=CIA equation where C is the runoff coefficient, I is the design intensity, and A is the drainage area for the BMP (acres).

Q = C*I*A Q = (Step 2) * (0.2 in/hr) * (Step 1) Q = 0.47 * 0.2 * 5 acres Q = ____0.47____cfs3

Flow-based BMP controls will need to be sized to treat a flow of 0.47 cfs of storm water. The next step is to select a treatment control to determine the size of the control measure. If you have selected a swale, you can find an example to size a swale in Attachment 3.


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Example 1B: Sizing for Volume-Based Controls Given: 5-acre (217,800 ft2) Low-Income Housing Apartment Complex


1-acre (43,560 ft2) square feet building coverage All runoff drains to a volume-based BMP

Task: To determine the BMP volume required to effectively detain and treat storm water runoff

using the preferred California BMP Handbook Method. Step 1: Total Drainage Area to BMP = A = 217,800 ft2 Step 2: Determine the mean annual rainfall at the site to determine correction factor.

a. Locate the site on Figure 1 (page C-8). The project site is located within the 22.5 range. The mean annual rainfall = 22.5 inches

b. Mean annual rainfall at Sacramento 5 ESE rain gauge = 19.1 inches

c. Correction Factor = (2a)/(2b)

= 22.5/19.1 = 1.18 a

Step 3: Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”,

using Table C.2a or C.2b (see page C-2) – See Step 2 from Example 1A. Runoff coefficient = 0.47

Step 4: Using Table C.3, find the unit storage volume for capture of 80% of annual runoff (inches)—assuming 48-hr drawdown.

Using the runoff coefficient 0.47 (from Step 3, above) interpolate value from Table C.3 between 0.45 and 0.50. Unit storage volume = 0.35 inches

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0.30 0.22 0.35 0.26 0.40 0.29 0.45 0.33 0.50 0.37 0.55 0.40 0.60 0.44 0.65 0.47 0.70 0.51 0.75 0.55 0.80 0.58 0.85 0.62 0.90 0.66 0.95 0.69 1.00 0.73

Step 5: Size the BMP The BMP volume is calculated by multiplying the correction factor by the unit storage volume by the drainage area. BMP Volume = Correction Factor * Unit Storage Volume * Drainage Area * (1ft/12in)

= (Step 2c) * (Step 4) * (Step 1a) = 1.18 * 0.35 inches * 217,800 ft2 * (1 foot/12 inches) = 7,496 cubic feet

Volume-based BMP controls will need to be sized to provide 7,496 cubic feet of storage for storm water treatment.

4 Source: CASQA, California Best Management Practice Handbook New Development and Redevelopment, Appendix D: “Unit Basin Volume for 80% Capture,” May 2003.

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Example 1C: Sizing for Flow-Based Controls Given: 5-acre (217,800 ft2) Low-Income Housing Apartment Complex


1-acre (43,560 ft2) square feet building coverage All runoff drains to flow-based BMP


using the California BMP Handbook Flow Method. Step 1: Total Drainage Area to BMP = A = 5 acres Step 2: Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”,


drainage area:




Concrete 0.80 0 Asphalt 0.70 87,120 Pervious Concrete 0.60 0 Cobbles 0.60 0 Pervious Asphalt 0.55 0 Natural Stone (without grout) 0.25 0 Turf Block 0.15 0 Brick (without grout) 0.13 0 Unit Pavers on Sand 0.10 0 Crushed Aggregate 0.10 0 Grass 0.10 87,120 Roofs 0.75 43,560



Σ(Area) surface

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C = (0.70 * 87,120) + (0.75 * 43,560) + (0.10 * 87,120) 217,800






0.50 0.70


0.30 0.40 0.50 0.60


0.50 0.60


In comparison, the two values are similar, however it is more accurate to compute an area-weighted “C-factor” based on the surfaces in the drainage area (Table C.2a) rather than to use the more general “Apartment” land use designation estimate from Table C.2b. Therefore, a runoff coefficient of 0.47 will be used.

Step 3: Determine the mean annual rainfall at the site to determine correction factor.


b. Mean annual rainfall at Sacramento 5ESE rain gauge = 19.1 inches

Correction Factor = (Step 3a)/(19.1) = 22.5/19.1 = 1.18 a

Step 4: Determine the corrected design rainfall intensity I = (Step 3b) * 0.19 = (1.18) * 0.19 = 0.22 in/hr

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Step 5: Determine the design flow (Q) using Q = CIA equation where C is the runoff coefficient,

I is the design intensity, and A is the drainage area for the BMP (acres).

Q = C*I*A Q = (Step 2) * (Step 4) * (Step 1) Q = 0.47 * 0.22 * 5 acres Q = ____0.52____cfs 5

Flow-based BMP controls will need to be sized to treat a flow of 0.52 cfs of storm water.


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Example 1D: Sizing for Flow-Based Controls Given: 5-acre (217,800 ft2) Low-Income Housing Apartment Complex


1-acre (43,560 ft2) square feet building coverage All runoff drains to a volume-based BMP


using the URQM Method. Step 1: Total Drainage Area to BMP = A = 217,800 ft2

Step 2: Amount of Impervious Area Draining to the BMP = 130,680 ft2

Step 3: Determine the impervious ratio, i:

i = amount of impervious area (ft2)/drainage area for the BMP (A) (ft2) = (Step 2)/(Step 1) = 130,680/217,800 = 0.60

Step 4: The watershed runoff coefficient, Cw Cw=0.858i3 – 0.78i2 + 0.774i + 0.04 =0.858(Step 3)3 – 0.78(Step 3)2 + 0.774(Step 3) + 0.04 Cw= 0.41

Step 5: Determine the mean annual rainfall at the site.

Locate the site on Figure 1 (page C-8). The project site is located within the 22.5 range. The mean annual rainfall = 22.5 inches

The mean storm event rainfall depth for the Sacramento 5 ESE is 0.55 inches. Sacramento’s Mean Annual Rainfall (in) is estimated to be 19.1 inches.

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P6 site

Event rainfall P6 SAC Step 6: Mean storm rainfall depth in inches, P6.

P6 site = 0.65 watershed inches

Step 7: Find a, the regression constant from least-squares analysis (unit less) Per the recommendation, use a 48-hour drain time.

a = 1.963

Step 8: Determine the maximized detention storage volume based on the volume capture ratio

Po = (a*Cw) * P6 Po = (Step 7 * Step 4) * Step 6 Po = (1.963 * 0.41) * 0.65 Po = 0.52 watershed inches

Step 9: BMP Design Volume

Design Volume = Po * A = (Step 8) * (Step 1) * 1 foot/12 inches

Design Volume = (0.52 inches) * (217,800 ft2) * 1 foot/12 inches Design Volume = 9,438 ft3


Event rainfall at site

Mean Annual Rainfall SAC Event rainfall P6 site

Mean Annual Rainfall site (from Figure 1) =

0.55 inches 19.1 inches

P6 site (Step 5) =

0.55 inches * 22.5 inches 19.1 inches

= =

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Parking: 2-acres (87,120 ft2) of pavement and parking 65,340 ft2 of asphalt surfaces 21,780 ft2 of concrete surfaces 81 apartments with:

1-acre (43,560 ft2) square feet building coverage Parking drains to flow-based BMP

Task: To determine the BMP flow required to effectively detain and treat storm water runoff using the preferred Uniform Intensity Method.

Step 1: Total Drainage Area to BMP = A = 2 acres Step 2: Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”,


drainage area:




Concrete 0.80 21,780 Asphalt 0.70 65,340 Pervious Concrete 0.60 0 Cobbles 0.60 0 Pervious Asphalt 0.55 0 Natural Stone (without grout) 0.25 0 Turf Block 0.15 0 Brick (without grout) 0.13 0 Unit Pavers on Sand 0.10 0 Crushed Aggregate 0.10 0 Grass 0.10 0 Roofs 0.75 0



Σ(Area) surface

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C = (0.80 * 21,780) + (0.70 * 65,340) 21,780 + 65,340






0.50 0.70


0.30 0.40 0.50 0.60


0.50 0.60


In comparison, the two values vary, however it is more accurate to only consider the parking areas to compute an area-weighted “C-factor” in the drainage area (Table C.2a) rather than to use the more general “Apartment” land use designation estimate from Table C.2b. Therefore, a runoff coefficient of 0.73 will be used.


Q = C*I*A Q = (Step 2) * (0.2 in/hr) * (Step 1) Q = 0.73 * 0.2 * 2 acres Q = 0.29 cfs 6



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Parking: 2-acres (87,120 ft2) of pavement and parking 65,340 ft2 of asphalt surfaces 21,780 ft2 of concrete surfaces 81 apartments with:

1-acre (43,560 ft2) square feet building coverage Parking drains to a volume-based BMP


using the preferred California BMP Handbook method. Step 1: Total Drainage Area to BMP = A = 87,120 ft2 Step 2: Determine the mean annual rainfall at the site to determine correction factor.


b. Mean annual rainfall at Sacramento 5 ESE rain gauge = 19.1 inches


= 22.5/19.1 = 1.18 a

Step 3: Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”

(see Step 2 from Example 2A). Runoff coefficient = 0.73


Using the runoff coefficient 0.73, interpolate the value from Table C.3 between 0.70 and 0.75. Unit storage volume = 0.53 inches

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0.30 0.22 0.35 0.26 0.40 0.29 0.45 0.33 0.50 0.37 0.55 0.40 0.60 0.44 0.65 0.47 0.70 0.51 0.75 0.55 0.80 0.58 0.85 0.62 0.90 0.66 0.95 0.69 1.00 0.73




7 Source: CASQA, California Best Management Practice Handbook New Development and Redevelopment, Appendix D: “Unit Basin Volume for 80% Capture,” draft May 2003.

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1-acre (43,560 ft2) square feet building coverage Rooftops drain to a flow-based BMP


using the preferred Uniform Intensity Method. Step 1: Total Drainage Area to BMP = A = 1 acre Step 2: Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”,


drainage area:



Area of Surface (ft2)

Concrete 0.80 0 Asphalt 0.70 0 Pervious Concrete 0.60 0 Cobbles 0.60 0 Pervious Asphalt 0.55 0 Natural Stone (without grout) 0.25 0 Turf Block 0.15 0 Brick (without grout) 0.13 0 Unit Pavers on Sand 0.10 0 Crushed Aggregate 0.10 0 Grass 0.10 0 Roofs 0.75 43,560



Σ(Area) surface

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C = (0.75 * 43,560) 43,560






0.50 0.70


0.30 0.40 0.50 0.60


0.50 0.60


In comparison, the two values vary, however it is more accurate to only consider the rooftop areas to compute an area-weighted “C-factor” in the drainage area (Table C.2a) rather than to use the more general “Apartment” land use designation estimate from Table C.2b. Therefore, a runoff coefficient of 0.75 will be used.


Q = C*I*A Q = (Step 2) * (0.2 in/hr) * (Step 1) Q = 0.75 * 0.2 * 1 acre Q = ____0.15____cfs 8



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1-acre (43,560 ft2) square feet building coverage Rooftops drain to volume-based BMP


using the preferred California BMP Handbook approach. Step 1: Total Drainage Area to BMP = A = 43,560 ft2 Step 2: Determine the mean annual rainfall at the site to determine correction factor.

a. Locate the site on Figure 1 (page C-8), The project site is located within the 22.5 range. The mean annual rainfall = 22.5 inches

b. Mean annual rainfall at Sacramento 5ESE rain gauge = 19.1 inches


= 22.5/19.1 = 1.18 a

Step 3: Determine the area-weighted runoff coefficient for the drainage area to the BMP, “C”,

see Step 2 from Example 2A. Runoff coefficient = 0.75


Using the runoff coefficient 0.75 the unit storage volume value from Table C.3 is 0.55. Unit storage volume = 0.55 inches

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0.30 0.22 0.35 0.26 0.40 0.29 0.45 0.33 0.50 0.37 0.55 0.40 0.60 0.44 0.65 0.47 0.70 0.51 0.75 0.55 0.80 0.58 0.85 0.62 0.90 0.66 0.95 0.69 1.00 0.73




9 Source: CASQA, California Best Management Practice Handbook New Development and Redevelopment, Appendix D: “Unit Basin Volume for 80% Capture,” January 2003

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ATTACHMENT 3.0

EXAMPLE CALCULATIONS FOR SIZING A VEGETATED SWALE: VILLAGE APARTMENTS

(FLOW-BASED CONTROL)

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Example Swale Calculations C.3-1 EOA, Inc. F:\FS11\FS11.60\Applicant Packet\Workshop\New Folder\AppCAttch3_Swale_final.doc DRAFT—Rev. April 11, 2005

Attachment 3.0 Example Calculations

Designing a Swale After determining the required design flow or volume, the next step is to select a treatment control and determine the size layout and characteristics necessary to effectively treat the storm water runoff. If you have selected to include a vegetated swale as part of your site design, the following example may provide assistance in calculating the swale size. The method used to size a swale is adapted from BASMAA’s Using Site Design Techniques to Meet Development Requirements (2003) with recommendations from various resources. Please note that sizing a swale is highly site specific; the area available for swale placement and vegetation cover and drainage patterns can have an impact on the design of the swale. This is an example to be used as general guidance on how to design a swale and actual designs should be adapted for the site specific conditions. Example: Sizing a Vegetated Swale The following scenario uses the flow calculated from Example 1A (pg C.2-2). Task: To determine the size of a swale based on the calculated flow required to effectively treat

storm water runoff. Step 1: Determine the flow of runoff.

The design flow is calculated using Example 1A of Attachment 2 (see page C.2-3).

Q = ____0.47____cfs

Recommendation: Use the preferred Uniform Intensity Method found on page C-3 to calculate runoff flow.

Step 2: Determine longitudinal swale slope.

Longitudinal Slope = 1% or 0.01

Recommendation: Design the longitudinal slope to be between 0.5% and 2.5% Step 3: Select vegetation cover.

Vegetation cover: Grass-lined

Recommendation: Vegetated swales may be planted with a variety of grasses, as well as shrubs and trees. For a list of recommended vegetation types, please refer to BASMAA’s Start at the Source (1999).

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Step 4: Determine vegetation height.

Vegetation Height = 2 inches or 0.17 feet

Recommendation: Vegetation should not be mowed shorter than 2 inches. For best treatment, the vegetation height should be designed to be 2 to 12 inches, and the design flow depth should not be greater than the vegetation height.

Step 5: Select a roughness coefficient or “Manning’s n” value for selected vegetation.

Roughness Coefficient = 0.20

Recommendation: Select a roughness coefficient to be between 0.20 and 0.251. Step 6: Select cross-sectional shape of swale. A typical cross-section is trapezoidal or parabolic in shape. This example will have a

trapezoidal shape. For small flow depths, a rectangular cross-sectional approximation can be used.

Recommendation: If designing a trapezoidal channel, the side slopes should not be steeper than 3:1 (H:V). (See the description on page C.3-4 for additional guidance on designing a trapezoidal channel.)

Step 7: Using Manning’s equation, determine the swale width.

Manning’s equation: Q = 1.49/n × R2/3 × S1/2 × A

Where Q = Flow n = Roughness coefficient (“Manning’s n”) R = Hydraulic radius = A / (b + 2y) for rectangular channels S = Slope of swale A = Cross-sectional area = b × y for rectangular channels y = Flow depth = vegetation height for treatment swale b = Swale width

1 The Manning’s roughness coefficient used for design of water quality swales is substantially greater than the values used for design of grassed ditches and channels. The reason for this is that in water quality swales, the depth of flow is less than or equal to the height of the grass, and in grassed ditches, the depth of flow is usually much greater than the height of the grass. The shallow flow in water quality swales allows the grass to remain upright during flow events, with the water flowing between the blades of grass. In a grassed ditch, the deeper flow tends to lay the grass down, with water flowing over the top of the grass. The net effect is a retarding of the flow in the water quality swale which is accounted for via the higher Manning’s “n” value. For depths greater than 5 inches, the Manning’s “n” may be reduced depending on the velocity and hydraulic radius (R) of the flow, according to the following chart:

If V * R < 0.15, n = 0.20 If 0.15 < V * R < 0.4, n = 0.15 If 0.4 < V * R < 0.75, n = 0.10 If 0.75 < V * R < 1.0, n = 0.08 If 1.0 < V * R < 2.0, n = 0.06 If 2.0 < V * R , n = 0.05

Source: V.J. Palmer and W.O. Ree, “Handbook of Channel Design for Soil and Water Conservation, USDA, 1954.

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Using an equation solver (or a trial-and-error procedure) and the variables determined above, calculate the swale width b using the following equation for rectangular channels: Q = 1.49/n × (b × y) 5/3 / (b + 2y) 2/3 × S1/2

Q = 0.47 cfs (Step1) n = 0.20 (Step 5) S = 0.01 (Step 2) y = 0.17 ft (Step 4)

The resulting swale width, b = 12.3 ft.

Recommendation: The width of the swale channel should be larger than 2 feet.

Step 8: Determine the flow velocity.

V = Flow/Cross-Sectional Area

= Q/A = Q/(b × y) = (Step1)/((Step 7) × (Step 4)) = 0.47 cfs/(12.3 ft × 0.17 ft) = 0.22 ft/sec

Recommendation: The design velocity should not exceed 1 foot per second.

Step 9: Select a detention time.

Detention Time (t) = 10 minutes = 600 seconds

Recommendation: Minimum detention time is 5 minutes; optimal detention time is 10 minutes. Since not all flow may enter at the top end of the swale, size for detention time of 10 minutes and ensure that most of the flow enters in the upper half of the swale.

Step 10: Determine the swale length. L = Velocity × Detention Time

= V × t = (Step 8) × (Step 9) = 0.22 ft/sec × 600 sec = 132 ft Recommendation: The length of the swale channel should be a minimum of 100 feet for a large drainage area. For smaller drainage areas (e.g., less than 0.5 acres), a shorter length with sufficient detention time may be acceptable.

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Step 11: Determine the land area required for the swale . Swale Area = Swale Length × Swale Width2 = L × b

= (Step 10) × (Step 7) = 132 ft × 12.3 ft = 1620 square feet Discussion of Results This example resulted in a large swale because it was designed to treat runoff from the entire site. In most cases, other site design measures, source controls and/or treatment controls would be used in conjunction with a swale or multiple swales to treat stormwater from the site. For example, assuming as in Example 2A (see Appendix C, Attachment 2) that the swale was designed to treat only the parking lot runoff rather than the entire site runoff, the flow rate to be treated would decrease to 0.29 cfs (page C.2-13), resulting in a smaller swale. Increasing the flow depth (and vegetation height) would also decrease the required channel width required for the channel; however, the velocity will increase, resulting in the need for a longer channel to achieve the same detention time. Also, the designer must be aware that increasing the flow depth may make the rectangular channel assumption less accurate. In this case, Manning’s equation and all equations that use the cross-sectional area will need to be adapted for a trapezoidal cross- sectional area and hydraulic radius as seen below3:

R = A / P P = b + 2y (1+z2)0.5

A = (b + zy) × y =y/2 × (a +b) a = top width z = 1/side slope = 1/(∆y/∆x) (Example: For a 3:1 side slope, z = 1/(1/3) = 3)

The results of these scenarios are summarized in the table below, for both a rectangular channel and a trapezoidal channel cross-section. For this design example, the results indicate that the rectangular cross-section assumption is reasonable for depths up to 6 inches. For depths greater than 6 inches, the swale width becomes smaller than the recommended 2-foot minimum width.

2 For a trapezoid channel, the top width of the swale would be used to calculate the land area needed for the swale. 3 Source: Hwang, Ned H.C.; Houghtalen, Robert J. Fundamentals of Hydraulic Engineering Systems. New Jersey. 1996. Third Edition.

b

a

∆y/∆x y

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Summary of Swale Scenarios (see assumptions below)

Area Flow Vegetation Rectangular Channel Trapezoidal Channel Treated Rate Height Width Length Top Width Bottom Width Length

Q (cfs) y (in) b (ft) L (ft) a (ft) b (ft) L (ft) Entire 0.47 2 12.3 132 12.4 12.3 132

Site 0.47 4 4.40 192 4.50 4.28 192 0.47 6 2.51 222 2.67 2.34 222

Parking 0.29 2 7.68 132 7.73 7.62 132 Lot 0.29 4 2.84 186 2.95 2.73 186

Only 0.29 6 1.69 204 1.85 1.52 204 Assumptions: Manning’s n = 0.20, longitudinal slope(S) = 0.01, detention time (t) = 10 minutes, and side slope = 3:1 (for trapezoidal channel). Other Design Considerations

• The presence of a subdrain below the flow line of the swale is often recommended depending on site conditions.

• There should be sufficient freeboard above the travel way of the swale to protect buildings. It is recommended that a 0.5-foot freeboard be provided between the 10-year peak flow surface elevation and the lowest adjacent building grade.

• The perforated pipe trench shall be backfilled with ¾-inch crushed rock with a 2-inch bed underneath and 6-inch cover. (Caltrans Standard Section 68-1.025 Permeable Materials Class 2). This rock layer shall be separated from the swale using a geofabric covered by a filter layer of sand or fine rock.

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ATTACHMENT 4.0

EXAMPLE CALCULATIONS FOR SIZING A DETENTION BASIN:

VILLAGE APARTMENTS (VOLUME-BASED CONTROL)

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Example Detention Basin Calculations C.4-1 EOA Inc./BKF Engineers F:\FS11\FS11.60\Applicant Packet\Workshop\New Folder\AppcAttch4.1_DetBasin.doc DRAFT—Rev. April 12, 2005

Attachment 4.0 Fairfield-Suisun Urban Runoff Management Program

Extended Detention Basin Design Guidance

Attachment 4.1. Fact Sheet

Description Extended detention ponds (a.k.a. dry ponds, dry extended detention basins, detention ponds, extended detention ponds) are basins whose outlets have been designed to detain the stormwater runoff from a water quality design storm for some minimum time (e.g., 48 hours) to allow particles and associated pollutants to settle. Unlike wet ponds, these facilities do not have a permanent pool. They can also be used to provide flood control by including additional flood detention storage.

Advantages and Limitations Advantages

• Due to the simplicity of design, extended detention basins are relatively easy and inexpensive to construct and operate.

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• Extended detention basins can provide substantial capture of sediment and the pollutants associated with particulates.

• Extended detention basins can be used to minimize the effects of hydromodification on receiving streams (if designed for that purpose).

Limitations

• Limitation of the diameter of the outlet orifice may not allow use of extended detention in watersheds of less than 5 acres.

• Extended detention ponds have only moderate pollutant removal when compared to some other structural stormwater practices, and they are relatively ineffective at removing dissolved pollutants. Effectiveness can be increased by the addition of other BMPs (such as media filters, infiltration trenches or vegetated swales) downstream of the detention pond outlet.

Design And Sizing Guidelines

• Extended detention basins shall be sized to capture the required water quality volume and provide a 48-hour detention time. At least 10 percent additional storage shall be provided to account for storage lost to deposited sediment.

• The outlet shall be sized with a drawdown time of 48 hours for the design water

quality volume. The recommended outlet has two low-level outlet orifices. The use of a single orifice is not recommended because of the risk of clogging, while use of more than two orifices is discouraged because the size of the holes is reduced, increasing susceptibility to clogging). The two orifices shall be at the same elevation and sized using the following equation1:

a = (1.44x10-6) * A * (H-Ho).5 / C

Where: a = total area of orifice in square feet

A = surface area of detention basin at mid-treatment storage elevation (square feet)

H = elevation of basin when full (feet) Ho = final elevation of basin when empty (bottom of lowest orifice) (feet) C = orifice coefficient (0.54 typical for orifice that is located at the floor of the

extended detention basin.) The diameter of the orifices shall be calculated using the following equation: d = ( (a * 4 * 144 ) / (n * pi ) ) 0.5

1 From Caltrans Storm Water Quality Handbooks, Project Planning and Design Guide, September 2002, p. B-18.

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d = orifice diameter (inches) n = number of orifices (2 is recommended)

• The orifices shall each be a minimum diameter of 1 inch. Extended detention basins are not practical for small drainage areas because the minimum orifice diameter cannot be met. Each orifice shall be protected from clogging using a screen with a minimum surface area of 50 times the area of the openings to a height of at least 6 times the diameter. The screen shall protect the orifice openings from runoff on all exposed sides.

• Extended detention basin shall have no greater than 3:1 side slopes.

• The optimal basin depth is between 2 and 5 feet.

• Vegetative Slope Protection

Between April 15 to October 1 – Place seed or sod on exposed sideslopes. No additional slope protection is required. Between October 1 and October 15 - Two Options are accepted: Option 1 - Seed the slope and place a 1-year biodegradable loose weave geofabric on the exposed seeded sideslopes to anchor soils. Option 2 - Place sod on exposed sideslopes. Between October 15 and April 15 – Place sod on exposed side slopes.

• Piping into the extended detention basin shall have erosion protection. The inlet pipe

shall have at least 1 foot of clearance to the pond bottom. As a minimum, a forebay with a 6-inch thick layer of Caltrans Section 72, Class 2 rock slope protection shall be placed at and below the inlet to the extent necessary for erosion protection. For each outlet, documentation shall be provided regarding adequacy of outlet protection, and a larger stone size may be necessary depending on the slope and the diameter of outfall.

• Extended detention basin shall empty within 72 hours of the end of a 6-hour, 100-

year storm event to avoid vector production. • Irrigation of the vegetation in the extended detention basin is optional. If necessary,

water truck irrigation, temporary pipe facilities or permanent pipe facilities may be used.

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• A 12-foot wide maintenance ramp leading to the bottom of the basin and a 12-foot wide perimeter access road shall be provided. If not paved, the ramp shall have a maximum slope of 5 percent. If paved, the ramp may slope up to 12 percent.

• The extended detention basin shall have a length to width ratio of at least 1.5:1.

• The basin bottom shall slope at least 0.5 percent to the discharge structure.

• If the groundwater level is within 10 feet of the ground surface, a liner shall be

provided.

• A fixed vertical sediment depth marker shall be installed in the forebay of the extended detention basin. The depth marker shall have a marking showing the depth where sediment removal is required. The marking shall be at a depth where the remaining storage equals the design water quality volume.

• A Maintenance Agreement shall be provided and signed by the applicant. The

Maintenance Agreement shall state the parties’ responsibility for maintenance and upkeep including mosquito control.

Maintenance Agreement The maintenance agreement for an extended detention basin shall include the following provisions:

• Vegetation shall be harvested annually during the summer. • The structural integrity of the outlet and berms shall be inspected semiannually.

• Accumulated trash and debris shall be removed from the extended detention basin at

the middle and end of the wet season. (January and April).

• Sediment shall be removed from the forebay when the sediment level reaches the level shown on the fixed vertical sediment marker.

• Pesticides and fertilizers shall not be used in the extended detention basin.

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Example Detention Basin Calculations C.4-5 EOA Inc./BKF Engineers F:\FS11\FS11.60\Applicant Packet\Workshop\New Folder\AppCattch4.2_DBWrksht.doc DRAFT—Rev. April 12, 2005

Attachment 4.2 Worksheet for Detention Basin Sizing

A. Basin Size A1. BMP Volume (from Attachment 2.0): VBMP = ________ A2. Additional Minimum Allowance for Sediment (10%)

(from Line A1 * 0.1): Vs = _________ A3. Minimum Volume for Extended Detention Basin

(Line A1 + Line A2): VT = _________ A4. The riser height shall be between 2 and 5 feet

depending on site conditions: H = __________

A5. Minimum Average Area of the Basin* (Line A3 / Line A4): Aave = ________

*The average area is approximate and is to be provided at the elevation midway between the flow line of the inlet orifice and the crest of the riser. A constant side slope of 3:1 is to be provided along the basin side slopes. Final volumes shall be checked based on grading including access amps, berm for sediment deposition area and variations in side slope.

B. Deposition Area At least 20 percent of the extended detention basin volume shall be within the sediment deposition area. This allowance is based on 10 percent volume for settling and a loss of up to 10 percent of the storage volume to settled material. The sediment deposition area shall be cleared once the sediment is above a mark indicating 10 percent of the basin volume is lost to deposition. B1. Sediment Deposition Area (Line A5 * 0.20): Ased = ________ C. Outlet Works Water Quality Outlet The low level outlet shall pass the water quality BMP Volume within 48 hours. The outlet shall consist of two equal size orifices that are at least one inch diameter. Extended detention basins are not practical for small drainage areas where this criterion cannot be met. The area of each orifice is calculated using the following equation:

. a = (1.44x10-6) * A * (H-Ho).5 / C

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A = surface area of constructed wetlands at mid-treatment storage elevation (square feet) (Line A5)

H = elevation of basin when full (feet) Ho = final elevation of basin when empty (bottom of lowest orifice) (feet) C = orifice coefficient (0.54 typical for orifice that is located at the floor of the

extended detention basin.)

C1. Area of orifice (square feet): a = __________ C2. Number of Orifices (2 is recommended): n =___________ C3. Diameter of orifice (inches)

((a (from Line C1) * 4 * 144 ) / ( n (from Line C2) * 3.14 ) )0.5 d = _______

(The two orifices may be different sizes. Round down to nearest half inch for orifice size. Low-level discharge may consist of stainless steel plate over larger opening within drop inlet.)

Overflow Outlet (Emergency Spillway) A raised drop inlet shall be provided as an emergency spillway. The overflow for the drop inlet shall be based on the 100-year flow to the extended detention basin. Storage in the basin will likely be filled prior to the peak of the 100-year storm. The basin shall pass the 100-year storm with 1 foot of head above the drop inlet (acting as a weir crest). An additional one foot of head shall be provided for freeboard. No attenuation of peak flows through the basin shall be done unless prior authorization is received from the City Engineer. C4. 100-Year Peak Flow Rate (from County of Solano

Drainage Manual): Q100 =_______ Check Drop Inlet for both weir flow and orifice flow. Weir Flow

P = ( Q100 / ( C * H1.5 ) * 1.25

Where: P = the minimum perimeter of the drop Inlet (feet)

Q100 = 100-year Event Peak Flow Rate (cubic feet per second) H = 1 foot head on the inlet C = weir coefficient (3.0 typical for smooth wall)

1.25 = Clogging factor

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C4a. Minimum perimeter based on weir flow: P = __________ Orifice Flow

A = ( Q100 / ( C * (2gH)0.5 ) ) * 2

Where: A = the minimum area of the drop inlet opening (square feet)

Q100 = 100-year Event Peak Flow Rate (cubic feet per second) C = orifice coefficient (0.6 typical for smooth wall with screen) g = gravity (32.2 feet per second2)

H = 1 foot head on the inlet 2 = Clogging factor

C4b. Minimum area based on orifice flow A = __________ User shall select a drop inlet from a standard manufacturer that provides the minimum area and perimeter. C5a. Proposed Drop Inlet (Length and Width in feet): L = __________ C5b. W = _________ C6a. Perimeter of Proposed Drop Inlet ( (Line C5a. + C5b.) * 2): P = _____ C6b. Area of Proposed Drop Inlet ( Line C5a. * C5b.): A = _____

Is Line 6a greater than Line 4a yes no Is Line 6b greater than Line 4b yes no Both answers should be yes. If no, explain why a larger drop inlet is not proposed. __________________________________________________________________ __________________________________________________________________

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Example Detention Basin Calculations C.4-8 EOA Inc./BKF Engineers F:\FS11\FS11.60\Applicant Packet\Workshop\New Folder\AppCAttch4.3.doc DRAFT—Rev. April 12, 2005

Attachment 4.3 Example Detention Basin Sizing Calculations

for Village Apartments Project

The following example is provided for illustrative purposes only and does not necessarily represent configuration or characteristics of the actual site. Sizing example is provided for only one scenario because extended detention basins are not practical for small areas. The example illustrates the FSURMP-preferred sizing methods available based on the FSURMP permit requirements.

Assumption1:

. • 5-acre (217,800 ft2

) Low-Income Housing Apartment Complex . Scenario:

1. Entire Site – All Runoff Drains to One BMP

Sizing for Volume-Based Controls Using FSURMP Method (see Attachment 2.0)

1 These examples are provided for illustrative purposes only and do not address the benefits of incorporating site design techniques into the design. Site design techniques can be incorporated into project designs that will result in the need for smaller treatment control sizes. For more information, see BASMAA’s Using Site Design Techniques to Meet Development Standards for Stormwater Quality, May 2003, available on the City’s website.

A. Basin Sizing A1. BMP Volume (from Attachment 2.0): VBMP = 7,496 ft3 A2. Additional Minimum Allowance for Sediment (10%)

(from Line A1 * 0.1): Vs = 750 ft3 A3. Minimum Volume for Extended Detention Basin

(Line A1 + Line A2): VT = 8,246 ft3 A4. The riser height shall be between 2 and 5 feet depending on site

conditions: H = 4 ft

A5. Minimum Average area of the basin (Line A3 / Line A4): Aave = 2,062

The average area is approximate and is to be provided at the elevation midway between the flow line of the inlet orifice and the crest of the riser. A constant side slope of 3:1 is to be provided along the basin side slopes. Final volumes shall be checked based on grading including access ramps, berm for sediment deposition area and variations in side slope.

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B. Deposition Area At least 20 percent of the extended detention basin volume shall be within the sediment deposition area. This allowance is based on 10 percent volume for settling and a loss of up to 10 percent of the storage volume to settled material. The sediment deposition area shall be cleared once the sediment is above a mark indicating 10 percent of the basin volume is lost to deposition. B1. Sediment Deposition Area (Line A5 * 0.20): Ased = 412 ft2 C. Outlet Works Water Quality Outlet The low level outlet shall pass the water quality BMP Volume within 48 hours. The outlet shall consist of two equal size orifices that are at least one inch diameter. Extended detention basins are not practical for small drainage areas where this criterion cannot be met. The area of each orifice is calculated using the following equation:

. a = (1.44x10-6) * A * (H-Ho).5 / C


A = surface area of constructed wetlands at mid-treatment storage elevation (square feet) (Line A5)

H = elevation of basin when full (feet) Ho = final elevation of basin when empty (bottom of lowest orifice) (feet) C = orifice coefficient (0.54 typical for orifice that is located at the floor of

the extended detention basin.)

C1. Area of orifice (square feet): a = 0.011 C2. Number of Orifices (2 is recommended): n = 2 C3. Diameter of orifice (inches)

((a (from Line C1) * 4 * 144 ) / ( n (from Line C2) * 3.14 ) )0.5 d = 1.0 (The two orifices may be different sizes. Round down to nearest half inch for orifice size. Low-level discharge may consist of stainless steel plate over larger opening within drop inlet.)

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Overflow Outlet (Emergency Spillway) A raised drop inlet shall be provided as an emergency spillway. The overflow for the drop inlet shall be based on the 100-year flow to the extended detention basin. Storage in the basin will likely be filled prior to the peak of the 100-year storm. The basin shall pass the 100-year storm with 1 foot of head above the drop inlet (acting as a weir crest). An additional one foot of head shall be provided for freeboard. No attenuation of peak flows through the basin shall be done unless prior authorization is received from the City Engineer. C4. 100-Year Peak Flow Rate (from County of Solano

Drainage Manual): Q100 =15 cfs (for: A = 5 acres, C100-year=0.8, I=3.7 inches /hr (MAP 22”, 13 minute time of concentration) Note: C for 100-year event peak flow calculation is greater than the C used to calculate treatment

flow) Check Drop Inlet for both weir flow and orifice flow. Weir Flow

P = ( Q100 / ( C * H1.5 ) * 1.25

Where: P = the minimum perimeter of the drop Inlet (feet)

Q100 = 100-year Event Peak Flow Rate (cubic feet per second) H = 1 foot head on the inlet C = weir coefficient (3.0 typical for smooth wall)

1.25 = Clogging factor C4a. Minimum perimeter based on weir flow: P = 6.3 Orifice Flow

A = ( Q100 / ( C * (2gH)0.5 ) ) * 2

Where: A = the minimum area of the drop inlet opening (square feet)

Q100 = 100-year Event Peak Flow Rate (cubic feet per second) C = orifice coefficient (0.6 typical for smooth wall with screen) g = gravity (32.2 feet per second2)

H = 1 foot head on the inlet 2 = Clogging factor

C4b. Minimum area based on orifice flow A = 6.9

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User shall select a drop inlet from a standard manufacturer that provides the minimum area and perimeter. C5a. Proposed Drop Inlet (Length and Width in feet): L = 3 C5b. W = 3 C6a. Perimeter of Proposed Drop Inlet ( (Line C5a. + C5b.) * 2): P = 12 C6b. Area of Proposed Drop Inlet ( Line C5a. * C5b.): A = 9

Is Line 6a greater than Line 4a yes no Is Line 6b greater than Line 4b yes no Both answers should be yes. If no, explain why a larger drop inlet is not proposed. __________________________________________________________________ __________________________________________________________________

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D-0

Appendix D

Stormwater Treatment Measures Maintenance Agreement


STORMWATER TREATMENT MEASURES MAINTENANCE AGREEMENT

RECITALS This Stormwater Treatment Measures Maintenance Agreement (“Agreement”) is entered into this by and between the City of (“City”) and , a property owner of real property described in this Agreement.

WHEREAS, On April 16, 2003, the Regional Water Quality Control Board, San Francisco Bay Region, adopted Order R2-2003-0034, CAS00612005 reissuing the Fairfield-Suisun Areawide NPDES municipal stormwater permit for the Fairfield-Suisun Sewer District (District) and the Cities of Fairfield and Suisun City which have joined together to form the Fairfield-Suisun Urban Runoff Management Program; and

WHEREAS, Provision C.3.e.ii. of this NPDES permit, and as it may be amended or reissued, requires the permittee public agencies to provide minimum verification and access assurances that all treatment measures shall be adequately operated and maintained by entities responsible for the stormwater treatment measures; and

WHEREAS, the Property Owner, , is the owner of real property commonly known as (the “Property”), and more particularly described in the attached legible reduced-scale copy of the Site Plan or comparable document Exhibit [XX] upon which storm water treatment measures are located or to be constructed; and

WHEREAS, the City is the permittee public agency with jurisdiction over the Property.

WHEREAS, the Property Owner, its administrators, co-owners, executors, successors, heirs, assigns or any other persons, including any homeowners association (hereinafter referred to as “Property Owner”) recognizes that the stormwater treatment measure(s) more particularly described and shown on , of which full-scale plans and any amendments thereto are on file with the [Planning] Department of the , must be installed and maintained as indicated in this Agreement and as required by the NPDES permit.

WHEREAS, the City and the Property Owner agree that the health, safety and welfare of the citizens of the City require that the stormwater treatment measure(s) detailed in the Site Plan or comparable document be constructed and maintained on the Property; and

WHEREAS, the City’s Stormwater Management Ordinance, guidelines, criteria and other written directions require that the stormwater treatment measure(s), as shown on the approved Site Plan or comparable document, be constructed and maintained by the Property Owner

THEREFORE, in consideration of the benefit received by the Property Owner as a result of the City’s approval of the Site Plan, the Property Owner hereby covenants and agrees with the City as follows:

SECTION 1: CONSTRUCTION OF TREATMENT MEASURES

The on-site stormwater treatment measure(s) shown on the Site Plan or comparable document shall be constructed by the Property Owner in strict accordance with the approved plans and specifications identified for the development and any other requirements thereto which have been

O&M Agreement D-1

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particularly described in Exhibit [XX]

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Exhibit

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Exhibit

Storm Water Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program approved by the City in conformance with appropriate City ordinances, guidelines, criteria and other written direction.

SECTION 2: OPERATION & MAINTENANCE RESPONSIBILITY

This agreement shall serve as the signed statement by the Property Owner accepting responsibility for operation and maintenance of stormwater treatment measures as set forth in this Agreement until the responsibility is legally transferred to another entity. Before the Property is legally transferred to another entity, the Property Owner shall provide to the City at least one of the following: 1) A signed statement from the public entity assuming post-construction responsibility for treatment measure maintenance and that the treatment measures meet all local agency design standards; or 2) Written conditions in the sales or lease agreement requiring the buyer or lessee to assume responsibility for operation and maintenance (O&M) consistent with this provision, which conditions, in the case of purchase and sale agreements, shall be written to survive beyond the close of escrow; or 3) Written text in project conditions, covenants and restrictions (CCRs) for residential properties assigning O&M responsibilities to the home owners association for O&M of the treatment measures; or 4) Any other legally enforceable agreement or mechanism that assigns responsibility for the maintenance of treatment measures. Upon transfer to a subsequent property owner, the transferee accepts the responsibility for operation and maintenance provided by this agreement.

SECTION 3: MAINTENANCE OF TREATMENT MEASURES

The Property Owner shall not destroy or remove the stormwater treatment measures from the Property nor modify the stormwater treatment system in a manner that lessens its effectiveness, and shall, at its sole expense, adequately maintain the stormwater treatment measure(s) in good working order acceptable to the City and in accordance with the maintenance plan agreed hereto and attached as . This includes all pipes, channels or other conveyances built to convey stormwater to the treatment measure(s), as well as all structures, improvements, and vegetation provided to control the quantity and quality of the stormwater. Adequate maintenance is herein defined as maintaining the described facilities in good working condition so that these facilities continue to operate as originally designed and approved. The maintenance plan shall include a detailed description of and schedule for long-term maintenance activities.

SECTION 4: SEDIMENT MANAGEMENT

Sediment accumulation resulting from the normal operation of the stormwater treatment measure(s) will be managed appropriately by the Property Owner. The Property Owner will provide for the removal and disposal of accumulated sediments. Disposal of accumulated sediments shall not occur on the Property, unless provided for in the maintenance plan. Any disposal or removal of accumulated sediments or debris shall be in compliance with all federal, state and local law and regulations.

SECTION 5: ANNUAL INSPECTION AND REPORT

The Property Owner shall, on an annual basis, complete the Treatment Measure Operation and Maintenance Inspection Report (annual report), attached to this agreement as Exhibit . The annual report shall include all completed Inspection and Maintenance Checklists for the reporting

O&M Agreement D-2

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Exhibit

Storm Water Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program period and shall be submitted to the District in order to verify that inspection and maintenance of the applicable stormwater treatment measure(s) have been conducted pursuant to this agreement. The annual report shall be submitted no later than December 31 of each year, under penalty of perjury, to the Urban Runoff Program Manager, Fairfield-Suisun Sewer District, 1010 Chadbourne Road, Fairfield, CA 94534. The Property Owner shall provide a record of the volume of all accumulated sediment removed from the treatment measure(s) in the annual report. The Property Owner shall conduct a minimum of one annual inspection of the stormwater treatment measure(s) before the wet season. This inspection shall occur between August 1st and October 1st each year. More frequent inspections may be required by the maintenance plan . The results of inspections shall be recorded on the Inspection and Maintenance Checklist(s) attached as .

SECTION 6: NECESSARY CHANGES AND MODIFICATIONS

At its sole expense, the Property Owner shall make changes or modifications to the stormwater treatment measure(s) and/or the long-term maintenance plan Exhibit [XX] as may be determined as reasonably necessary by the City to ensure that treatment measures are properly maintained and continue to operate as originally designed and approved.

SECTION 7: ACCESS TO THE PROPERTY

The Property Owner hereby grants permission to the City; the District: the San Francisco Bay Regional Water Quality Control Board (Regional Board); the Solano County Mosquito Abatement District (SCMAD); and their authorized agents and employees to enter upon the Property at reasonable times and in a reasonable manner to inspect, assess or observe the stormwater treatment measure(s) in order to ensure that treatment measures are being properly maintained and are continuing to perform in an adequate manner to protect water quality and the public health and safety. This includes the right to enter upon the Property when it has a reasonable basis to believe that a violation of this Agreement, the City’s stormwater management ordinance, guidelines, criteria, other written direction, or the Fairfield-Suisun Urban Management Program’s NPDES municipal stormwater permit (Regional Board Order R2-2003-0034, and any amendments or reissuances of this permit) is occurring, has occurred or threatens to occur. The above listed agencies also have a right to enter the Property when necessary for abatement of a public nuisance or correction of a violation of the ordinance guideline, criteria or other written direction. Whenever possible, the City, RWQCB, or the Mosquito Abatement District shall provide reasonable notice to the Property Owner before entering the property.

SECTION 8: FAILURE TO MAINTAIN TREATMENT MEASURES

In the event either the Property Owner or a transferee or assignee pursuant to Section 2 fails to maintain the stormwater treatment measure(s) as shown on the approved Site Plan or comparable document in good working order acceptable to the City and in accordance with the maintenance plan incorporated in the Agreement, the City, and its authorized agents and employees with reasonable notice, may enter the Property and take whatever steps it deems necessary and appropriate to return the treatment measure(s) to good working order. Such notice will not be necessary if emergency conditions require immediate remedial action. This provision shall not be construed to allow the City to erect any structure of a permanent nature on the Property. It is expressly understood and agreed that the City is under no obligation to maintain or repair the treatment measure(s) and in no event shall this Agreement be construed to impose any such obligation on the City.

SECTION 9: REIMBURSEMENT OF CITY EXPENDITURES

In the event the City, pursuant to the Agreement, performs work of any nature (direct or indirect), including any reinspections or any actions it deems necessary or appropriate to return

O&M Agreement D-3

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Exhibit

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Exhibit

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[XX] measures are X

Storm Water Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program the treatment measure(s) in good working order as indicated in Section 8, or expends any funds in the performance of said work for labor, use of equipment, supplies, materials, and the like, either the Property Owner or any transferee or assignee pursuant to Section 2 shall reimburse the City, or shall forfeit any required bond upon demand within thirty (30) days of receipt thereof for the costs incurred by the City hereunder. If these costs are not paid within the prescribed time period, the City may assess the Property Owner the cost of the work, both direct and indirect, and applicable penalties. Said assessment shall be a lien against the Property, or prorated against the beneficial users of the Property or may be placed on the property tax bill and collected as ordinary taxes by the City. The actions described in this section are in addition to and not in lieu of any and all legal remedies as provided by law, available to the City as a result of the Property Owner’s failure to maintain the treatment measure(s).

SECTION 10: INDEMNIFICATION

The Property Owner shall indemnify, hold harmless and defend the City, the District and their authorized agents, officers, officials and employees from and against any and all claims, demands, suits, damages, liabilities, losses, accidents, casualties, occurrences, claims and payments, including attorney fees claimed or which might arise or be asserted against the City or the District that are alleged or proven to result or arise from the construction, presence, existence or maintenance of the treatment measure(s) by the Property Owner, the City or the District. In the event a claim is asserted against the City, the District or its authorized agents, officers, officials or employees, the City shall promptly notify the Property Owner and the Property Owner shall defend at its own expense any suit based on such claim. If any judgment or claims against the City, the District or their authorized agents, officers, officials or employees shall be allowed, the Property Owner shall pay for all costs and expenses in connection herewith. This section shall not apply to any claims, demands, suits, damages, liabilities, losses, accidents, casualties, occurrences, claims and payments, including attorney fees claimed which arise due solely to the negligence or willful misconduct of the City or the District.

SECTION 11: NO ADDITIONAL LIABILITY

It is the intent of this agreement to insure the proper maintenance of the treatment measure(s) by the Property Owner; provided, however, that this Agreement shall not be deemed to create or effect any additional liability not otherwise provided by law of any party for damage alleged to result from or caused by storm water runoff.

SECTION 12: PERFORMANCE FINANCIAL ASSURANCE

The City may request the Property Owner to provide a performance bond, security or other appropriate financial assurance providing for the maintenance of the stormwater treatment measure(s) pursuant to the City’s ordinances, guidelines, criteria or written direction.

SECTION 13: TRANSFER OF PROPERTY

13.1 Agreement Runs with the Land. This Agreement shall run with the title to the land. The Property Owner hereby subjects its interest in the Property and the Project to the covenants and restrictions set forth in this Agreement. The City and Property Owner hereby declare their express intent that the covenants and restrictions set forth herein shall be deemed covenants running with the land and shall be binding upon and inure to the benefit of the heirs, administrators, executors, successors in interest, transferees, and assigns of the Property Owner and City, regardless of any assignment, conveyance or transfer of the Property or any part thereof or interest therein. Any successor-in-interest to the Property Owner including without limitation any purchaser, transferee or lessee of the Property shall be subject to all of the duties and

O&M Agreement D-4

Storm Water Requirements Project Applicant Package Fairfield-Suisun Urban Runoff Management Program obligations imposed hereby for the full term of this Agreement. Each and every contract, deed, ground lease or other instrument affecting or conveying the Property shall conclusively be held to have been executed, delivered and accepted subject to the covenants, restrictions, duties and obligations set forth herein, regardless of whether such covenants, restrictions, duties and obligations are set forth in such contract, deed, ground lease or other instrument. If any such contract, deed, ground lease or other instrument has been executed prior to the date hereof, the Property Owner hereby covenants to obtain and deliver to City an instrument in recordable form signed by the parties to such contract, deed, ground lease or other instrument pursuant to which such parties acknowledge and accept this Agreement and agree to be bound hereby.

13.2 Equitable Servitudes. Property Owner agrees for itself and for its successors that in the event that a court of competent jurisdiction determines that the covenants herein do not run with the land, such covenants shall be enforced as equitable servitudes against the Property and in favor of City.

13.3 Touches and Concerns. The Parties hereby declare that it is their understanding and intent that the burden of the covenants set forth herein touch and concern the land in that they restrict the use of the Property. The Parties further declare that it is their understanding that the benefit of such covenants touch and concern the land by guaranteeing the health, safety, and welfare of the citizens of the City. The covenants, conditions and restrictions hereof shall apply uniformly to the Property in order to establish and carry out a common plan for the use, development and improvement of the Property.

SECTION 14: SEVERABILITY

The provisions of this Agreement shall be severable and if any phrase, clause, section, subsection, paragraph, subdivision, sentence or provision is adjudged invalid or unconstitutional by a court of competent jurisdiction, or the applicability to any Property Owner is held invalid, this shall not affect or invalidate the remainder of any phrase, clause, section, subsection, paragraph, subdivision, sentence or provision of this Agreement.

SECTION 15: RECORDATION

This Agreement shall be recorded by the Property Owner, or by the City by mutual agreement, within days after the execution date of this Agreement as stated above among the deed records of the County Recorder’s Office of the County of Solano, California at the Property Owner’s expense.

SECTION 16: RELEASE OF AGREEMENT

In the event that the City determines that the stormwater treatment measures located on the Property are no longer required, then the City, at the request of the Property Owner shall execute a release of this Inspection and Maintenance Agreement, which the Property Owner, or the City by mutual agreement, shall record in the County Recorder’s Office at the Property Owner’s expense. The stormwater treatment measure(s) shall not be removed from the Property unless such a release is so executed and recorded.

O&M Agreement D-5


O&M Agreement D-6

SECTION 17: EFFECTIVE DATE AND MODIFICATION

This Agreement is effective upon the date of execution as stated at the beginning of this Agreement. This Agreement shall not be modified except by written instrument executed by the City and the Property -Owner at the time of modification. Such modifications shall be effective upon the date of execution and shall be recorded.

_____________________________________ ___________________ Signature for the City Date _____________________________________________________________ Type or print name and title _____________________________________ ___________________ Property Owner Signature Date _____________________________________________________________ Type or print Property Owner name and address

Treatment Measure Operation and Maintenance Inspection Report

Fairfield-Suisun Urban Runoff Management Program

Reporting Period: to Date: ____________ Time: This inspection report, with the attached completed inspection checklists, documents the inspection and maintenance of the identified storm water treatment measure(s).

I. PROJECT INFORMATION 1. ID # or Assessor Parcel Number: 2. Year of Installation

3. Project Type: Residential Commercial Industrial Multi-use Road Institutional Other

4. Facility Name: ___________________________________________________________________________

Site Address: ___________________________________________________________________________

Contact Name: Phone:

5. If the property owner is different than the contact name, fill out information below:

Owner Name: Title: ______________________________

Owner’s Address: Phone: ___________________

6. If the BMP operator is different than the contact name, fill out information below:

Name: Title: ______________________________

Address: Phone: ___________________

7 . Responsible for Documentation: Property owner BMP Operator Contractor Other: _____________

II. STORMWATER TREATMENT MEASURES (Provide total number of treatment measures inspected) 1. Biofiltration

Vegetated Swale _____________ Vegetated Buffer Strip _________ Bioretention _________________ Roof Gardens ________________ Planter Boxes ________________

Detention Extended Detention Basin ______ Wet Pond ___________________ Wetland ____________________

Structural Drain Insert Porous Pavement Media Filter Hydrodynamic Separator Vortex Separator Water Quality Inlet Underground Detention Systems Wet Vault

Infiltration Infiltration Basin __________ Infiltration Trench _________ Exfiltration Trench ________ Retention/Irrigation ________

Other (describe): ________________________________

__________________________

2. Comments/Notes:

III. SEDIMENT REMOVAL

1. Total amount of accumulated sediment removed: cubic yards or pounds (circle one).

2. The sediment was removed and disposed of as follows:

IV. STATEMENT OF TREATMENT MEASURE CONDITION 1. Based on the inspections documented in the attached checklists, is(are) the treatment measure(s) identified in this report present, functional and being maintained as required by the Maintenance Plan? Yes No

2. If “No”, describe problem, proposed corrective action, and schedule of correction: V. CERTIFICATION I hereby certify, under penalty of perjury, that the information presented in this report and attachments is true and complete:

Signature of Property Owner or Other Responsible Party Date

E-mail: Type or Print Name

F:\FS11\FS11.60\O&M\C.3.Reporting\inspection report_form-040706.doc 4/7/2006 Inspectors:

Fairfield-Suisun Urban Runoff Management Program Maintenance Inspection Verification Program Guidance

Appendix E Treatment Control Descriptions

Bioretention The bioretention best management practice (BMP) functions as a soil and plant-based filtration device that removes pollutants through a variety of physical, biological, and chemical treatment processes. These facilities normally consist of a grass buffer strip, sand bed, ponding area, organic layer or mulch layer, planting soil, and plants. The runoff’s velocity is reduced by passing over or through

the buffer strip and the runoff is subsequently distributed evenly along a ponding area. Exfiltration of the water stored in the bioretention area planting soil into the underlying native soils occurs over a period of days. Alternatively liners may be used in areas with high groundwater levels. (CASQA) Catch Basin Inserts Drain inserts are manufactured filters or fabric placed in a drop inlet to remove sediment and debris. There are a multitude of inserts of various shapes and configurations, typically falling into one of three different groups: socks, boxes, and trays. The sock types consists of a fabric, usually constructed of polypropylene. The fabric may be attached to a frame or the grate of the inlet may hold the sock. Socks are meant for vertical (drop) inlets. Boxes are constructed of plastic or wire mesh. Typically a polypropylene “bag” is placed in the wire mesh box. The bag takes the form of the box. Most box products are one box; that is, the setting area and the area for filtration through media occur in the same box. Some products consist of one or more trays or mesh grates. The trays may hold different types of media. Filtration media vary by manufacturer. Types include polypropylene, porous polymer, treated cellulose, and activated carbon. Due to the need for intensive inspection and maintenance of these devices, San Francisco Bay Regional Water Quality Control Board Staff (RWQCB) discourages their use. (Lichten, Keith (RWQCB), Letter to BASMAA, 2004; O’Hara, Jan (RWQCB), SCVURPPP C.3 Workshop communication, June 3, 2004)) Conveyance Systems (pipes & ditches) Pipe and open ditches are used to convey storm water. Culverts are enclosed conveyance structures that are typically installed along drainage ditches and streams to provide crossings at roadways, driveways, or other obstructions. They are most commonly pipes (e.g., circular, elliptical, or arch-shaped), but can also be rectangular concrete structures (i.e., box culverts). Improperly designed and constructed culverts can create barriers to fish passage and migration in natural stream channels. Also, culverts can cause serious erosion problems in adjacent stream channels in not appropriately designed and constructed. (Bellevue)

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Debris Barriers A debris barrier (e.g., trash rack) is a grill, grate or other device at the intake of a channel, pipe, drain or spillway. Their main purpose is to prevent trash and other oversized debris from entering the structure while not obstructing the flow of storm water. (Truckee Meadows Structural Controls Design Manual)

Detention Ponds Dry extended detention ponds (a.k.a. dry ponds, extended detention basins, detention ponds, extended detention ponds) are basins whose outlets have been designed to detain the storm water runoff from a water quality design storm for some minimum time (e.g., 48 hours) to allow particles and associated pollutants to settle. Unlike wet ponds, these facilities do not

have a large permanent pool. They can also be used to provide flood control by including additional flood detention storage. (CASQA)

Green Roofs/Roof Gardens Roof gardens, or green-roofs, are vegetated roof systems that retain and filter storm water and provide aesthetic, noise buffering, thermal and energy conservation benefits. A green roof consists of a special root repelling membrane, a drainage system, a lightweight growing medium and plants. (SCVURPPP)

Filter Strips Grassed buffer strips (vegetated filter strips, filter strips, and grassed filters) are vegetated surfaces that are designed to treat sheet flow from adjacent surfaces. Filter strips function by slowing runoff velocities and allowing sediment and other pollutants to settle, and by providing some infiltration into underlying soils. Filter strips were originally used as an agricultural treatment practice and have more recently evolved into an urban runoff control practice. With proper design and maintenance, filter strips can provide relatively high pollutant removal. In addition, the public views them as landscaped amenities and not as storm water infrastructure. Consequently, there is little resistance to their use. (CASQA) Media Filters

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Storm water media filters are usually two-chambered including a pretreatment settling basin and a filter bed filled with sand or other absorptive filtering media. As storm water flows into the first chamber, large particles settle out, and then finer particles and other pollutants are removed as storm water flows through the filtering media in the second chamber. There are a number of design variations including the Austin sand filter, Delaware sand filter and multi-chambered treatment train (MCTT). Two are similar in that they use cartridges of a standard size. The cartridges are placed in vaults; the number of cartridges required is a function of the design flow rate. The water flows laterally (horizontally) into the cartridge to a centerwell, then downward to an underdrain system. The third product is a flatbed filter, similar in appearance to sand filters. (CASQA) Oil/Water Separators

Oil/water separators are used to treat storm water runoff from high use developments that generate relatively large quantities of oil and grease (e.g., shopping centers, roadways, and parking lots). Included are two types of oil/water separators: the conventional gravity API (American Petroleum Institute) separator and coalescing plate separators (CPS). (Bellevue) The conventional gravity API separator consists of a large vault equipped with baffles to prevent oil and other floating debris from passing through the separator. The baffles extend down vertically from the top of the vault, trapping floatable material within the vault chambers. In addition, a baffle is usually installed on the bottom at the upstream end of the vault to trap suspended sediment. Oil absorbent pads or mechanical skimmers can also be installed in the main chamber to remove separated oil. (Bellevue) Coalescing plate separators are similar to API separators except that a bank of closely spaced, inclined, corrugated plates is inserted into the separator chamber to improve removal efficiency. Consequently, these systems are usually smaller in size than the conventional API separator. The plates are usually constructed of fiberglass, stainless steel, or polypropylene. Because of the closely spaced configuration of the plates, sediment and other debris can easily clog these systems. Therefore, to work effectively, the coalescing plates must be kept clean. (Bellevue) FSM separators are simple containment devices capable of trapping floatable materials. They consist of a vault or manhole structure that is equipped with a downturned elbow on the outlet. These devices are not as effective as CPS and API separators in separating oil; they function primarily for spill containment and as floating debris traps. (Bellevue) Porous Pavement Porous pavement is a permeable pavement surface that allows surface runoff to infiltrate into the subsoil. Stone reservoirs are often constructed below pavement to temporarily store surface runoff prior to infiltration; or are used to collect storm water in underlying drain pipes prior to discharge off-site. Pollutants are removed by absorption onto soil particles and by bacterial decomposition in the reservoir or in surface soils. There are many types of porous pavement including: turf blocks (grass planted through load-bearing plastic or concrete frames), modular blocks (stone or concrete blocks interspersed

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with pervious material such as gravel or sand), granular pavement (crushed aggregrate with wood mulch or cobbles), porous asphalt, and pervious concrete. (SCVURPPP) Sand Filters Sand can be used to filter suspended solids, phosphorus, and oils from storm water. A typical sand filtration system consists of a pre-settling basin, a flow spreader over the sand bed, and an underdrain system. After treatment in the filter, runoff is collected in the underdrain system and is discharged. Structures may be constructed either above ground in a basin or below ground in a vault. Sand filter vaults can either be rectangular or linear. (Bellevue) Filters require special care to prevent the filter surface from becoming clogged. Once the filter begins to clog, the hydraulic capacity drops dramatically, causing the filter to go into overflow stage much more frequently than usual. As a result, treatment performance is severely reduced. Therefore, pretreatment systems such as biofilters, wet ponds, or wet vaults are often installed immediately upstream of filtration systems to prolong the life of the filter media. (Bellevue) Vaults, Tanks, & Pipes Like ponds, vaults, tanks, and pipes are storage facilities that can be designed as detention, water quality, or combined systems, except that vaults are underground rather than above ground facilities. Underground facilities are generally used to manage storm water from smaller sites (e.g., less than 5 acres). Vaults are typically constructed of reinforced concrete, while tanks and pipes are usually made of corrugated metal or plastic pipe. (Bellevue)

Vegetated Swales Vegetated swales are open, shallow channels with vegetation covering the side slopes and bottom. The swales collect and slowly convey runoff flow to downstream discharge points. They are designed to treat runoff through filtering by the vegetation in the channel, filtering through a subsoil matrix, and/or infiltration into the underlying soils. Swales can

be natural or manmade. They trap particulate pollutants (suspended solids and trace metals), promote infiltration, and reduce the flow velocity of storm water runoff. Vegetated swales can serve as part of a storm water drainage system and can replace curbs, gutters and storm sewer systems. (CASQA) Vortex Separators Vortex separators (alternatively, swirl concentrators) are gravity separators, and in principle are essentially wet vaults. The difference from wet vaults, however, is that the vortex separator is round, rather than rectangular, and the water moves in a centrifugal fashion before exiting. By having the water move in a circular fashion, rather than a

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straight line as is the case with a standard wet vault, it is possible to obtain significant removal of suspended sediments and attached pollutants with less space. Vortex separators were originally developed for combined sewer overflows (CSOs), where they are used primarily to remove coarse inorganic solids. Vortex separation has been adapted to storm water treatment by several manufacturers. (CASQA)

Wet Ponds Wet ponds (a.k.a. storm water ponds, retention ponds, wet extended detention ponds) are constructed basins that have a permanent pool of water throughout the year (or at least throughout the wet season) and differ from constructed wetlands primarily in having a greater average depth. Ponds treat incoming storm water runoff by settling and biological uptake. The primary removal mechanism is

settling as storm water runoff resides in this pool, but pollutant uptake, particularly of nutrients, also occurs to some degree through biological activity in the pond. Wet ponds are among the most widely used storm water practices. While there are several different versions of the wet pond design, the most common modification is the extended detention wet pond, where storage is provided above the permanent pool in order to detain storm water runoff and promote settling. (CASQA) Wet Vaults A wet vault is an underground vault with a permanent water pool, generally 3 to 5 feet deep. Wet vaults are designed to store urban runoff, dissipate energy, and provide for settling of particulate matter. They are located on a storm water line or at the end of pipe and would most typically be used at commercial, industrial, or public road sites where space is and issue. The vault may also have a constricted outlet that causes a temporary rise of the water level (i.e., extended detention) during each storm. This live volume generally drains within 12 to 48 hours after the end of each storm. (CASQA, Metropolitan Council, Minnesota Urban Small Sites BMP Manual 3-281)

Inspection and Maintenance Checklist Bioretention

Property Address: Property Owner: Treatment Measure No: Date of Inspection: Type of Inspection: Pre-rainy season Monthly Quarterly Annual Re-inspection1 Inspector(s):

Defect Conditions When Maintenance Is Needed

Maintenance Needed? (Y/N)

Comments (Describe maintenance completed; and if any needed maintenance was not conducted, note what is needed and when it will be done)

Results Expected When Maintenance Is Performed

General

Trash & Debris

•

•

Trash and debris accumulated in basin Visual evidence of dumping

Trash and debris cleared from site.

Contaminants and Pollution

Any evidence of oil, gasoline, contaminants or other pollutants

No contaminants or pollutants present.

Vegetation • When the planted vegetation becomes excessively tall.

• When nuisance weeds and other vegetation start to take over.

Vegetation mowed per specifications or maintenance plan, or nuisance vegetation removed so that flow is not impeded. Vegetation should never be mowed lower than the design flow depth. Remove clippings from the area and dispose appropriately.

Tree/Brush Growth and Hazard Trees

•

•

• •

Growth does not allow maintenance access or interferes with maintenance activity Dead, diseased, or dying trees

Trees do not hinder maintenance activities. Remove hazard trees as approved by the City. (Use a certified Arborist to determine health of tree or removal requirements)

1 Re-inspection of a previously-noted maintenance issue.

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Bioretention Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Erosion Eroded over 2 in. deep where cause of damage is still present or where there is potential for continued erosion.

Cause of erosion is managed appropriately. Areas remulched to fill in void areas.

Sediment Accumulated sedimentaffects inletting or outletting condition of the facility.

Sediment removed and area reseeded if necessary to control erosion.

Damaged Pipes

Any part of the piping that is crushed or deformed more than 20% or any other failure to the piping.

Pipe repaired or replaced.

Rodent Holes If facility acts as a dam or berm, any evidence of rodent holes, or any evidence of water piping through dam or berm via rodent holes.

• The design specifications are not compromised by holes.

• Any rodent control activities are in accordance with applicable laws and do not affect any protected species.

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Inspection and Maintenance Checklist Vegetated Swale

Property Address: rty Owner: Prope Treatment Measure No.: Date of Inspection: Type of Inspection: Pre-rainy season Monthly Quarterly Annual Re-inspection1 Inspector(s):



Comments (Describe maintenance completed; and if any needed maintenance was not conducted, note when it will be done)


Sediment Accumulation on Vegetation

Sediment depth exceeds 2 inches. Sediment deposits on vegetated treatment area of the swale removed. When finished, swale should be level from side to side and drain freely toward outlet. There should be no areas of standing water once inflow has ceased.

Standing Water

When water stands in the swale between storms and does not drain freely.

There should be no areas of standing water once inflow has ceased. Any of the following may apply: sediment or trash blockages removed, improved grade from head to foot of swale, removed clogged check dams, added underdrains or converted to a wet swale.

Flow spreader (if any)

Flow spreader uneven or clogged so that flows are not uniformly distributed through entire swale width.

Spreader leveled and cleaned so that flows are spread evenly over entire swale width.

Constant Baseflow

When small quantities of water continually flow through the swale, even when it has been dry for weeks, and an eroded, muddy channel has formed in the swale bottom.

No eroded, muddy channel on the bottom. A low-flow pea-gravel drain may be added the length of the swale. Any broken or incorrect irrigation components repaired or replaced.

Poor Vegetation Coverage

When planted vegetation is sparse or bare or eroded patches occur in more than 10% of the swale bottom.

Vegetation coverage in more than 90% of the swale bottom. Reason why growth of planted vegetation is poor determined and condition corrected. Sparse areas re-planted with plugs of vegetation from the upper slope: plant in the swale bottom at 8-inch intervals, or re-seed into loosened, fertile soil.

1Re-inspection of a previously-noted maintenance issue.

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Vegetated Swale Inspection Checklist Inspection Date.: Property Address: Treatment Measure No.:

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Defect Conditions When MaintenanceIs Needed


Comments (Describe maintenance completed and if needed maintenance was not conducted, note what is needed and when it will be done)


Vegetation When the planted vegetation becomes excessively tall; when nuisance weeds and other vegetation start to take over.

Vegetation mowed per specifications or maintenance plan, or nuisance vegetation removed so that flow is not impeded. Vegetation should never be mowed lower than the design flow depth. Remove clippings from the swale and dispose appropriately.

Excessive Shading

Growth of planted vegetation is poor because sunlight does not reach swale.

Healthy growth of planted vegetation. If possible, trim back over-hanging limbs and remove brushy vegetation on adjacent slopes.

Inlet/Outlet Inlet/outlet areas clogged with sediment and/or debris.

Material removed so that there is no clogging or blockage in the inlet and outlet areas.

Trash and Debris Accumulation

Trash and debris accumulated in the swale.

Trash and debris removed from swale.

Mosquito Vector Breeding

Suitable habitats exist for mosquito production (e.g., standing water for more than 72 hours in areas accessible to mosquitoes).

Water drainage rates are restored to design standards. Standing water no longer exists or is inaccessible to mosquitoes.

Erosion/ Scouring

Eroded or scoured swale bottom due to flow channelization, or higher flows.

No erosion or scouring in swale bottom. For ruts or bare areas less than 12 inches wide, repair the damaged area by filling with crushed gravel. If bare areas are large, generally greater than 12 inches wide, the swale should be re-graded and re-seeded. For smaller bare areas, overseed when bare spots are evident, or take plugs of grass from the upper slope and plant in the swale bottom at 8-inch intervals.

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Inspection and Maintenance Checklist Vegetated Buffer Strips / Filter Strips






General

Sediment Accumulation on Grass

Sediment depth exceeds 2 inches.

Sediment deposits on grass removed. When finished, filter strip should be level from side to side and drain freely toward outlet. There should be no areas of standing water once inflow has ceased.


Vegetation mowed per specifications or maintenance plan, or nuisance vegetation removed so that flow is not impeded. Vegetation should never be mowed lower than the design flow depth. Remove clippings from the swale and dispose appropriately.

Trash & Debris Accumulation

Trash and debris accumulated on the filter strip.

Trash and debris removed from filter strip.

Erosion/ Scouring

Eroded or scoured areas due to flow channelization, or higher flows.

No erosion or scouring in filter strip bottom. For ruts or bare areas less than 12 inches wide, repair the damaged area by filling with crushed gravel. The grass will creep in over the rock in time. If bare areas are large, generally greater than 12 inches wide, the filter strip should be re-graded and re-seeded. For smaller bare areas, overseed when bare spots are evident.


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Buffer Strips/Filter Strips Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Flow spreader Flow spreader uneven or clogged so that flows are not entirely uniformly distributed through entire filter width.

Spreader leveled and cleaned so that flows are spread evenly over entire filter width.

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Inspection and Maintenance Checklist Baffle Oil/Water Separators (API Type)

Date of Inspection: Property Address: Property Owner: Treatment Measure No: Date of Inspection: Type of Inspection: Pre-rainy season Monthly Quarterly Annual Re-inspection1 Inspector(s):





General

Monitoring Inspection of discharge water for obvious signs of poor water quality.

Effluent discharge from vault should be clear without thick visible sheen.

Sediment Accumulation

Sediment depth in bottom of vault exceeds 6-inches in depth.

No sediment deposits on vault bottom that would impede flow though the vault and reduce separation efficiency.


Trash and debris accumulation in vault, or pipe inlet/outlet, floatables and non-floatables.

Trash and debris removed from vault and inlet/outlet piping.

Oil Accumulation

Oil accumulations that exceed 1-inch at the surface of the water.

Extract oil from vault by vactoring. Disposal in accordance with state and local rules and regulations.

Damaged Pipes

Inlet or outlet piping damaged or broken and in need of repair.

Pipe repaired and/or replaced.

Access Cover Damaged/Not Working

Cover cannot be opened, corrosion/deformation of cover.

Cover repaired to proper working specifications or replaced.

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Baffle Oil/Water Separators Inspection Checklist Inspection Date.: Property Address: Treatment Measure No.:

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Vault Structure Damage – Includes Cracks in Walls, Bottom, Damage to Frame and/or Top Slab

• Cracks wider than 1/2-inch or evidence of soil particles entering the structure through the cracks, or maintenance/inspection personnel determine that the vault is not structurally sound.

• Cracks wider than 1/2-inch at the joint of any inlet/outlet pipe or evidence of soil particles entering through the cracks.

• Vault replaced or repairs made so that vault meets design specifications and is structurally sound.

• Vault repaired so that no cracks exist wider than

1/4-inch at the joint of the inlet/outlet pipe.

Baffles Baffles or walls corroding, cracking, warping and/or showing signs of failure as determined by maintenance/inspection staff.

Baffles repaired or replaced to specifications.

Access Ladder Damage

Ladder is corroded or deteriorated, not functioning properly, not securely attached to structural wall, missing rungs, has cracks and/or is misaligned.

Ladder replaced or repaired to specifications, and is safe to use as determined by inspection personnel.


Suitable habitats exist for mosquito production (e.g., standing water in areas accessible to mosquitoes). Most likely through unsealed areas or openings.

Standing water no longer exists or openings are sealed to make water inaccessible to mosquitoes.

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Inspection and Maintenance Checklist Catch Basin Inserts






General


When sediment forms a cap over the insert media of the insert and/or unit.

Sediment cap is removed on the insert media and its unit.


Trash and debris accumulates on insert unit creating a blockage/restriction.

Trash and debris removed from insert unit. Runoff freely flows into catch basin.

Media Insert Not Removing Oil

Effluent water from media insert has a visible sheen.

Effluent water from media insert is free of oils and has no visible sheen.

Media Insert Water Saturated

Catch basin insert is saturated with water and no longer has the capacity to absorb.

Media insert replaced.

Media Insert Oil Saturated

Media oil saturated due to petroleum spill that drains into catch basin.

Media insert replaced.

1 Re-inspection of a previously-noted maintenance issue

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Catch Basin Inserts Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Media Insert Use Beyond Normal Product Life

Media has been used beyond the typical average life of media insert product.

Media insert replaced. Remove and replace media at regular intervals, depending on insert product.

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Inspection and Maintenance Checklist Coalescing Plate Oil/Water Separators






General

Monitoring Inspection of discharge water for obvious signs of poor water quality.

Effluent discharge from vault should be clear without thick visible sheen.


Sediment depth in bottom of vault exceeds 6-inches in depth and/or visible signs of sediment on plates.

No sediment deposits on vault bottom and plate media that would impede flow though the vault and reduce separation efficiency.


Trash and debris accumulation in vault, or pipe inlet/outlet, floatables and non-floatables.


Oil Accumulation


Oil is extracted from vault using vactoring methods. Coalescing plates are cleaned by thoroughly rinsing and flushing with water. There should be no visible oil depth on water.

Damaged Coalescing Plates

Plate media broken, deformed, cracked and/or showing signs of failure.

An entire portion of the media pack or the entire plate pack is replaced depending on severity of failure.

Damaged Pipes




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Coalescing Plate Oil/Water Separators Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Baffles Baffles or walls corroding, cracking, warping and/or showing signs of failure as determined by maintenance/inspection staff.




• Cracks wider than 1/2-inch at the joint of any inlet/outlet pipe or evidence of soil particles entering through the cracks.







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Inspection and Maintenance Checklist Conveyance Systems (Pipes & Ditches)






Pipes

Sediment and Debris

Accumulated sediment exceeds 20% of the diameter of the pipe.

All sediment and debris removed from the pipe.

Vegetation Vegetation that reduces free movement of water through pipes.

All vegetation removed so water flows freely through pipes.

Damaged Pipe • Protective coating is damaged; rust is causing more than 50% deterioration to any part of pipe.

• Any dent that decreases the cross section area of pipe by more than 20% or puncture that impacts performance.

Pipe is repaired or replaced.

Open Ditches

Trash and Debris

•

•

Trash and debris accumulated in basin. Visual evidence of dumping.

Trash and debris is cleared from ditches.


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Conveyance Systems Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Sediment Accumulated sediment that exceeds 20% of the design depth.

Sediment removed and discarded of properly. Ditch cleansed of all excessive standards sediment and debris so that it matches design.

Vegetation Excessive vegetation that reduces free movement of water through ditches.

Water flows freely through ditches.

Erosion Damage to Slopes and Channel Bottom

Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted berm embankment.

Slopes should be stabilized using appropriate erosion control measure(s); e.g., rock reinforcement, planting of grass, compaction.

Rock Lining Out of Place or Missing (If Applicable)

Maintenance person can see native soil beneath the rock lining.

Rock lining replaced to design standards.

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Inspection and Maintenance Checklist Debris Barrier (e.g., Trash Racks)






General

Trash & Debris

Trash or debris that is plugging more than 20% of the openings in the barrier.

Barrier cleared to design flow capacity.

Metal

Damaged/ Missing Bars

• Bars are bent out of shape more than 3 inches.

• Bars are missing or entire barrier missing.

• Bars are loose and rust is causing 50% deterioration to any part of barrier.

• Bars are in place with no bends more than ¾ inch.

• Bars are in place according to design.

• Barrier replaced or repaired to design standards.

Inlet/Outlet Pipe

Debris barrier missing or not attached to pipe.

Barrier firmly attached to pipe.


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Inspection and Maintenance Checklist Detention Basin






General

Trash & Debris

•

•



Poisonous Vegetation and Noxious Weeds

Poisonous or nuisance vegetation or noxious weeds, (e.g., morning glory, English ivy, reed canary grass, Japanese knotweed, purple loosestrife, blackberry, Scotch broom, poison oak, stinging nettles, star thistle, or devil’s club.)

Management of poisonous or noxious vegetation. Use Integrated Pest Management techniques to control noxious weeds or invasive species.


Any evidence of oil, gasoline, contaminants or other pollutants.



The design specifications are not compromised by holes. Any rodent control activities are in accordance with applicable laws and do not affect any protected species.


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Detention Basin Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:





Insects Insects such as wasps and hornets interfere with maintenance activities.

Insects do not interfere with maintenance activities. Use IPM techniques to control (e.g., traps, etc.)


Suitable habitats exist for mosquito production (e.g., standing water for more than 72 hours in areas accessible to mosquitoes; overgrowth of cattails).

Water drainage rates are restored to design standards. Standing water no longer exists or is inaccessible to mosquitoes. Cattails removed or shaded out by nearby trees.


•

•

• •

Growth does not allow maintenance access or interferes with maintenance activity. Dead, diseased, or dying trees.

Trees do not hinder maintenance activities. Remove hazard trees as approved by the City.

(Use a certified Arborist to determine health of tree or removal requirements)

Side Slopes

Erosion •

•

Eroded over 2 in. deep where cause of damage is still present or where there is potential for continued erosion. Any erosion on a compacted berm embankment.

Cause of erosion is managed appropriately. Side slopes or berm are restored to design specifications, as needed.

Storage Area

Sediment Accumulated sediment>10% of designed basin depth or affects inletting or outletting condition of the facility.

Sediment cleaned out to designed basin shape and depth; basin reseeded if necessary to control erosion.

Liner (If Applicable)

Liner is visible and has more than three 1/4-inch holes in it.

Liner repaired or replaced. Liner is fully covered.

Emergency Overflow/ Spillway and Berms


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Detention Basin Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:






Settlement Berm settlement 4 inches lower than the design elevation.

Dike is built back to the design elevation.

Tree Growth Tree growth on berms or emergency spillway >4 ft in height or covering more than 10% of spillway.

•

•

Trees should be removed. If root system is small (base less than 4 inches) the root system may be left in place. Otherwise the roots should be removed and the berm restored. A civil engineer should be consulted for proper berm/spillway restoration.

Emergency Overflow/ Spillway

Rock is missing and soil is exposed at top of spillway or outside slope.

Rocks and pad depth are restored to design standards.

Debris Barriers (e.g., Trash Racks)

Trash and Debris

Trash or debris is plugging openings in the barrier.

Trash or debris is removed.


Bars are missing, loose, bent out of shape, or deteriorating due to excessive rust.

Bars are repaired or replaced to allow proper functioning of trash rack.

Inlet/Outlet Pipe

Debris barrier is missing or not attached to pipe.

Debris barrier is repaired or replaced to allow proper functioning of trash rack.

Fencing and Gates

Missing or broken parts

Any defect in or damage to the fence or gate that permits easy entry to a facility.

Fencing and gate are restored to design specifications.

Deteriorating Paint or Protective Coating

Part or parts that have a rusting or scaling condition that has affected structural adequacy.

Paint or protective coating is sufficient to protect structural adequacy of fence or gate.

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Inspection and Maintenance Checklist Green Roofs (or Roof Gardens)






General


Vegetation mowed per specifications or maintenance plan, or nuisance vegetation removed so that flow is not impeded. Vegetation should never be mowed lower than the design flow depth.

Poor Vegetation Coverage

When planted vegetation is sparse or bare or eroded patches occur in more than 10% of the roof garden.

Vegetation coverage is more than 90% of the roof garden. The reason why growth of planted vegetation is poor has been determined and the condition corrected. Re-plant with plugs of vegetation or re-seed into loosened, fertile soil.

Membrane and Roof Structure

Membrane or roof structure is compromised by either roots and/or water damage.

Membrane and roof are repaired and/or replaced as needed. Many membrane companies now have warranties to guarantee the life of the membrane.

Drainage Inlets

Inlets to roof drainage system clogged with sediment and/or debris.

Material removed so that there is no clogging or blockage in the inlet and outlet areas. Repair or replace drain inlet pipe.

Automated Irrigation Systems

Irrigation system leaking or malfunctioning.

Irrigation system repaired or replaced partially or entirely if necessary. (Test automated systems to ensure proper operation).


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Green Roofs Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Standing Water

When water stands in the green roof between storms and does not drain freely.

There should be no areas of standing water once inflow has ceased. Any of the following may apply: sediment or trash blockages removed, improved grade of the roof, removed clogged check dams, added underdrains or converted to a blue roof.


Suitable habitats exist for mosquito production (e.g., standing water for more than 72 hours in areas accessible to mosquitoes)

Water drainage rates are restored to design standards. Standing water no longer exists or is inaccessible to mosquitoes.


Trash and debris accumulated on the roof.

Trash, debris and fallen leaves removed from surrounding roof area.

Erosion/ Scouring

Eroded or scoured areas due to wind or water.

No erosion or scouring on green roof. Supplement soil substrate/growth medium and control any existing erosion.

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Inspection and Maintenance Checklist Media Filter (e.g., Stormfilter, AquaFilter, Aqualogic)






Below Ground Vault

Sediment Accumulation on Media

Sediment depth exceeds 1/4-inch.

No sediment deposit which would impede permeability of the compost media.

Sediment Accumulation in Vault

Sediment depth exceeds 6-inches in first chamber.

No sediment deposits in vault bottom of first chamber.


Trash and debris accumulated on compost filter bed.

Trash and debris removed from compost filter bed.

Sediment in Drain Pipes/ Clean-Outs

When drain pipes and/or clean-outs become full with sediment and/or debris.

Sediment and debris removed.

Damaged Pipes

Any part of the pipes that are crushed or damaged due to corrosion and/or settlement.



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Media Filters Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:






Cover cannot be opened, corrosion/deformation of cover. Maintenance person cannot remove cover using normal lifting pressure.



• Cracks wider than ½-inch or evidence of soil particles entering the structure through the cracks, or maintenance/inspection personnel determine that the vault is not structurally sound.

• Cracks wider than ½-inch at the joint of any inlet/outlet pipe or evidence of soil particles entering though the cracks.



¼-inch at the joint of the inlet/outlet pipe.

Baffles Baffles corroding, cracking, warping and/or showing signs of failure as determined by maintenance/inspection staff.





Below Ground Cartridge Type

Filter Media Drawdown of water through the media takes longer than 1 hour and/overflow occurs frequently.

Media cartridges replaced.


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Media Filters Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:






Short Circuiting

Flows do not properly enter filter cartridges.

Filter cartridges replaced.

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Inspection and Maintenance Checklist Porous Pavement

(e.g., turf block, modular blocks, granular pavement, porous asphalt, pervious concrete) Property Address: Property Owner: Treatment Measure No: Date of Inspection: Type of Inspection: Pre-rainy season Monthly Quarterly Annual Re-inspection1 Inspector(s):





General


By visual inspection, little or no water flows through pavement during heavy rain storms, usually causing ponding.

The percolation rate of water through the porous spaces in the pavement and in the underlying base and soils is restored. Impacts from fine particulate matter reduced by using pretreatment BMPs in adjacent areas.

Erosion Soil from adjacent areas washed onto pavement.

Landscaped areas that are well maintained should prevent soil from eroding onto pavement.

Overflow Devices (Pipes)

Trash and debris accumulated on overflow devices.

Trash and debris removed from overflow devices.


Vegetation mowed per specifications or maintenance plan, or nuisance vegetation removed so that flow is not impeded. Clippings removed from the porous pavement and disposed of appropriately.

Porous Asphalt and Concrete

Debris, Organic Matter, and Sediment

Porous pavement clogging due to debris, organic matter and sediment.

Vacuum sweep porous asphalt or concrete systems (with proper disposal of removed materials), followed by high pressure hosing to free pores on the surface and result in no clogging.


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Porous Pavement Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Any evidence of oil, gasoline, contaminants or other pollutants

No contaminants or pollutants present, this will prevent soil or groundwater contamination from occurring. Spills must be vacuumed immediately and followed by jet washing.

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Inspection and Maintenance Checklist Sand Filter (Below Ground/Enclosed)






Below Ground Vault

Sediment Accumulation on Sand Media Section


No sediment deposits on sand filter section that would impede permeability of the filter section.

Sediment Accumulation in Pre-Setting Portion of Vault

Sediment accumulation in vault bottom exceeds the depth of the sediment zone plus 6-inches.

No sediment deposits in first chamber of vault.


Trash and debris accumulated in vault, or pipe inlet/outlet, floatables and non-floatables.


Sediment in Drain Pipes/ Clean-Outs

When drain pipes and/or clean-outs become full with sediment and/or debris.

Sediment and debris removed.

Short Circuiting

When seepage/flows occur along the vault walls and corners. Sand eroding near inflow area.

Sand filter media section re-laid and compacted along perimeter of vault to form a semi-seal. Erosion protection added to dissipate force of incoming flow and to curtail erosion.

Damaged Pipes




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Sand Filters (Below Ground/Enclosed) Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Cover cannot be opened, corrosion/deformation of cover. Maintenance person cannot remove cover using normal lifting pressure.


Ventilation Ventilation area blocked or plugged.

Blocking material removed or cleared from ventilation area. A specified % of the vault surface area must provide ventilation to the vault interior (see design specifications).



• Cracks wider than 1/2-inch at the joint of any inlet/outlet pipe or evidence of soil particles entering though the cracks.




Baffles/ Internal Walls

Baffles or walls corroding, cracking, warping and/or showing signs of failure as determined by maintenance/inspection staff.

Baffles or walls repaired or replaced to specifications.


Ladder is corroded or deteriorated, not functioning properly, not securely attached to structural wall, missing rungs, has cracks and/or misaligned.

Ladder replaced or repaired to specifications, and is safe to use as determined by inspection personnel

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Inspection and Maintenance Checklist Sand Filter (Above Ground/Open)






Above Ground (Open Sand Filter)

Sediment Accumulation on top layer


No sediment deposit on surface of sand filter that would impede permeability of the filter section.


Trash and debris accumulated on the sand filter bed.

Trash and debris removed from sand filter bed.

Sediment/ Debris in Clean-Outs

When the clean-outs become full or partially plugged with sediment and/or debris.

Sediment removed from clean-outs.

Sand Filter Media

Drawdown of water through the sand filter media takes longer than 24-hours, and/or flow through the overflow pipes occurs frequently.

Top several inches of sand are scraped. May require replacement of entire sand filter depth depending on extent of plugging (a sieve analysis is helpful to determine if the lower sand has too high a proportion of fine material).

Prolonged Flows

Sand is saturated for prolonged periods of time (several weeks) and does not dry out between storms due to continuous base flow or prolonged flows from detention facilities.

Low, continuous flows are limited to a small portion of the facility by using a low wooden divider or slightly depressed sand surface.


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Sand Filters (Above Ground/Open) Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Short Circuiting

When flows become concentrated over one section of the sand filter rather than dispersed.

Flow and percolation of water through the sand filter is uniform and dispersed across the entire filter area.

Erosion Damage to Slopes

Erosion over 2-inches deep where cause of damage is prevalent or potential for continued erosion is evident.

Slopes stabilized using proper erosion control measures.

Rock Pad Missing or Out of Place

Soil beneath the rock is visible.

Rock pad replaced or rebuilt to design specifications.

Flow spreader Flow spreader uneven or clogged so that flows are not uniformly distributed across sand filter.

Spreader leveled and cleaned so that flows are spread evenly over sand filter.

Damaged Pipes

Any part of the piping that is crushed or deformed more that 20% or any other failure to the piping.

Pipe repaired or replaced.

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Inspection and Maintenance Checklist Vaults, Tanks, and Pipes






Storage Area

Plugged Air Vents

One-half of the cross section of a vent is blocked at any point or the vent is damaged.

Vents open and functioning.

Debris and Sediment

Accumulated sediment depth exceeds 10% if the diameter of the storage area for ½ length of storage vault or any point depth exceeds 15% diameter. (Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than ½ length of tank.)

All sediment and debris removed from storage area.

Joints Between Tank/Pipe Section

Any openings or voids allowing material to be transported into facility. (Will require engineering analysis to determine structural stability).

All joints between tank/pipe sections are sealed.


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Vaults, Tanks and Pipes Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:





Tank Pipe Bent Out

Any part of tank/pipe is bent out of shape more than 10% of its design shape. (Review required by engineer to determine structural stability).

Tank/pipe repaired or replaced to design.

Vault Structure Includes Cracks in Wall, Bottom, Damage to Frame and/or Top Slab

Cracks wider than 1/2-inch and any evidence of soil particles entering the structure through the cracks, or maintenance/inspection personnel determines that the vault is not structurally sound. Cracks wider than 1/2-inch at the joint of any inlet/outlet pipe or any evidence of soil particles entering the vault through the walls.

Vault replaced or repaired to design specifications and is structurally sound. No cracks more than 1/2-inch wide at the joint of the inlet/outlet pipe.


Suitable habitats exist for mosquito production (e.g., standing water in areas accessible to mosquitoes)

Standing water no longer exists or is inaccessible to mosquitoes.

Manhole

Cover Not in Place

Cover is missing or only partially in place. Any open manhole requires maintenance.

Manhole is closed.

Locking Mechanism Not Working

Mechanism cannot be opened by one maintenance person with proper tools. Bolts into frame have less than 1/2 inch of thread (may not apply to self-locking lids).

Mechanism opens with proper tools.


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Vaults, Tanks and Pipes Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:






Cover Difficult to Remove

One maintenance person cannot remove lid after applying normal lifting pressure. Intent is to keep cover from sealing off access to maintenance.

Cover can be removed and reinstalled by one maintenance person.

Ladder Rungs Unsafe

Ladder is unsafe due to missing rungs, misalignment, not securely attached to structure wall, rust, or cracks.

Ladder meets design standards. Allows maintenance person safe access.

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Inspection and Maintenance Checklist Vortex Separators

(e.g., Vortechs Concentrators, Hydro International Downstream Defender, V2B1, Aqua Shield Aqua-Swirl Concentrator, and CDS units)






General


Trash and debris accumulated in vault, pipe or inlet/outlet (includes floatables and non-floatables).

Trash and debris removed from vault with an vactor truck. It may be necessary to remove and dispose of the floatables separately due to the presence of petroleum product.



Remove sediment from vault.

Oil Accumulation


Extract oil from vault by vactoring. Disposal in accordance with state and local rules and regulations.

Damaged Pipes

Inlet/outlet piping damage or broken and in need of repair.



Cover cannot be opened or removed, especially by one person.

Cover repaired or replaced to proper working specifications.


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Vortex Separators Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Blocking material removed or cleared from ventilation area. A specified % of the vault meets design specifications and is structurally sound.


• Maintenance/inspection personnel determine that the vault is not structurally sound.

• Cracks wider than 1/2-inch at the joint of any inlet/outlet pipe or evidence of soil particles entering though the cracks.







Ladder is corroded or deteriorated, not functioning properly, not securely attached to structural wall, missing rungs, has cracks and/or is misaligned. Confined space warning sign missing.

Ladder replaced or repaired to specifications, and is safe to use as determined by inspection personnel. Sign warning of confined space entry requirements is clearly visible. Ladder and entry notification complies with OSHA standards.


Suitable habitats exist for mosquito production (e.g., standing water in areas accessible to mosquitoes)

Standing water no longer exists or is inaccessible to mosquitoes.

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Inspection and Maintenance Checklist Wet Ponds






General Water level

First cell is empty, doesn't hold water.

Line the first cell to maintain at least 4 feet of water. Although the second cell may drain, the first cell must remain full to control turbulence of the incoming flow and reduce sediment resuspension.

Trash & Debris

Trash and debris accumulated in pond.

Trash and debris removed from pond.

Sediment Accumulation in the Pond Bottom

Sediment accumulations in pond bottom that exceeds the depth of sediment zone.

Sediment removed from pond bottom.

Oil Sheen on Water

Prevalent and visible oil sheen.

Oil removed from water using oil-absorbent pads or vactor truck. Source of oil located and corrected. If chronic low levels of oil persist, plant wetland plants such as Juncus effuses (soft rush) which can uptake small concentrations of oil.

Erosion Erosion of the pond’s side slopes and/or scouring of the pond’s bottom, that exceeds 6-inches, or where continued erosion is prevalent.

Slopes stabilized using proper erosion control measures and repair methods.


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Wet Ponds Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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Settlement of Pond Dike/Berm

Any part of these components that has settled 4-inches or lower than the design elevation, or inspector determines dike/berm is unsound.

Dike/berm is repaired to specifications.

Internal Berm Berm dividing cells should be level.

Berm surface is leveled so that water flows evenly over entire length of berm.

Overflow Spillway


Rocks replaced to specifications.


Suitable habitats exist for mosquito production (e.g., standing water for more than 72 hours in areas accessible to mosquitoes; presence of excessive cattails or other vegetation precluding access for vector control purposes.)

Standing water no longer exists or is inaccessible to mosquitoes. Vegetation controlled using IPM techniques.

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Inspection and Maintenance Checklist Wetland






General

Trash & Debris

•

•



Poisonous Vegetation and noxious weeds

Poisonous or nuisance vegetation or noxious weeds, e.g., morning glory, English ivy, reed canary grass, Japanese knotweed, purple loosestrife, blackberry, Scotch broom, poison oak, stinging nettles, star thistle, or devil’s club.

Management of poisonous or noxious vegetation. Use Integrated Pest Management techniques to control noxious weeds or invasive species.


Any evidence of oil, gasoline, contaminants or other pollutants.



The design specifications are not compromised by holes. Any rodent control activities are in accordance with applicable laws and do not affect any protected species.

1 Re-inspection of a previously noted-maintenance issue

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Wetland Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:






Insects do not interfere with maintenance activities.


Suitable habitats exist for mosquito production (e.g., standing water in areas accessible to mosquitoes).

Standing water no longer exists or is inaccessible to mosquitoes or mosquito fish are used to eliminate mosquito population.


•

•

• •

Growth does not allow maintenance access or interferes with maintenance activity. Dead, diseased, or dying trees.

Trees do not hinder maintenance activities. Remove hazard trees as approved by the City.

(Use a certified Arborist to determine health of tree or removal requirements)

Side Slopes

Erosion •

•

Eroded over 2 in. deep where cause of damage is still present or where there is potential for continued erosion. Any erosion on a compacted berm embankment.

Cause of erosion is managed appropriately. Side slopes or berm are restored to design specifications, as needed.

Storage Area

Sediment Accumulated sediment>10% of designed basin depth or affects inletting or outletting condition of the facility.

Sediment cleaned out to designed basin shape and depth; basin reseeded if necessary to control erosion.

Liner (If Applicable)

Liner is visible and has more than three 1/4-inch holes in it.

Liner repaired or replaced. Liner is fully covered.

Emergency Spillway and Embankment

Settlement Emmbankment settlement 4 inches lower than the design elevation.

Dike is built back to the design elevation.


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Wetland Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:






Tree Growth Tree growth on berms or emergency spillway >4 ft in height or covering more than 10% of spillway.

•

•

Trees should be removed. If root system is small (base less than 4 inches) the root system may be left in place. Otherwise the roots should be removed and the berm restored. A civil engineer should be consulted for proper berm/spillway restoration.

Emergency Overflow/ Spillway


Rocks and pad depth are restored to design standards.

Debris Barriers (e.g., Trash Racks)

Trash and Debris

Trash or debris is plugging openings in the barrier.

Trash or debris is removed.


Bars are missing, loose, bent out of shape, or deteriorating due to excessive rust.

Bars are repaired or replaced to allow proper functioning of trash rack.

Inlet/Outlet Pipe

Debris barrier is missing or not attached to pipe.

Debris barrier is repaired or replaced to allow proper functioning of trash rack.

Fencing and Gates

Missing or broken parts

Any defect in or damage to the fence or gate that permits easy entry to a facility.

Fencing and gate are restored to design specifications.

Deteriorating Paint or Protective Coating

Part or parts that have a rusting or scaling condition that has affected structural adequacy.

Paint or protective coating is sufficient to protect structural adequacy of fence or gate.

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Inspection and Maintenance Checklist Wet Vaults (e.g., Bay Saver, Stormvault, and Stormceptor)






General


Trash and debris accumulated in vault, pipe or inlet/outlet (includes floatables and non-floatables).

Trash and debris removed from vault.



Remove sediment from vault.

Damaged Pipes

Inlet/outlet piping damage or broken and in need of repair.



Insects do not interfere with maintenance activities.


Cover cannot be opened or removed, especially by one person.

Cover repaired or replaced to proper working specifications.


Blocking material removed or cleared from ventilation area. A specified % of the vault meets design specifications and is structurally sound.


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Wet Vaults Inspection Checklist Inspection Date: Property Address: Treatment Measure No.:

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• Maintenance/inspection personnel determine that the vault is not structurally sound.

• Cracks wider than1/2-inch at the joint of any inlet/outlet pipe or evidence of soil particles entering through the cracks.







Ladder is corroded or deteriorated, not functioning properly, not securely attached to structural wall, missing rungs, has cracks and/or is misaligned. Confined space warning sign missing.

Ladder replaced or repaired to specifications, and is safe to use as determined by inspection personnel. Replace sign warning of confined space entry requirements. Ladder and entry notification complies with OSHA standards.

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