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Resolution No. 7683
l RESOLUTION NO. 7683 2 A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF 3 VERNON APPROVING AND ADOPTING THE DEVELOPMENT PLANNING PORTION OF THE CITY OF VERNON'S STORM WATER 4 MANAGEMENT PROGRAM 5 WHEREAS, on December 7, 1993, the City Council of the City of 6 Vernon approved and adopted Resolution No. 6366, whereby it became a 7 co-permittee under the National Pollutant Discharge Elimination System 8 ("NPDES") Permit issued to the County of Los Angeles ("the Permit"); 9 and 10 WHEREAS, the City of Vernon, in cooperation with the County 11 of Los Angeles and 84 other co-permittees, participated in the 12 development of five Model Programs for Storm Water Management within 13 Los Angeles County; and 14 WHEREAS, as part of the City's participation in the 15 countywide NPDES Permit, the City is required to develop a Storm Water 16 Management Program that is consistent with the Model Programs that 17 have been developed by the County of Los Angeles; and 18 WHEREAS, the City's Storm Water Management Program consists 19 of the following elements: 20 • Public Education, which was approved by Resolution No. 21 7142 adopted by the City Council on June 23, 1998; 22 • Development Planning; 23 • Development Construction, which was approved by Resolution 24 No. 7465 adopted by the City Council on December 21, 1999; 25 • Public Agency Activities; 26 • Illicit Connections/Illicit Discharge Elimination, which 27 was approved by Resolution No. 7465 adopted by the City 21Council on December 21, 1999; and I WHEREAS, on March 8, 2000, the Executive Officer of the 2 California Regional Water Quality Control Board for the Los Angeles 3 Region issued a Final Approved Standard Urban Storm Water Mitigation 4 Plan for Los Angeles County and Cities in Los Angeles County (the 5 "SUSMP"), which was modified on October 5, 2000, setting forth the 6 requirements to be implemented by all jurisdictions discharging storm 7 water under the NPDES Permit for Municipal Storm Water and Urban 8 Runoff Management.Programs in Los Angeles County; and 9 WHEREAS, by adoption of Ordinance No. 1082, the City Council 10 of the City of Vernon intends to meet the requirement of the 'Regional 11 Board that all permittees under the Los Angeles County NPDES Permit 12 amend codes and promulgate ordinances by January 15, 2001, to give 13 legal effect to the SUSMP requirements; and 14 WHEREAS, the City of Vernon's SUSMP Ordinance No. 1082 will 15 take effect by February 15, 2001, thereby giving Vernon the legal 16 authority to implement the SUSMP; and 17 WHEREAS, the City has prepared a Development Planning Program 18 that satisfies the requirements of the Model Programs that have been 19 developed by the County of Los Angeles and desires to adopt the 20 Program. 21 NOW, THEREFORE, BE IT RESOLVED BY THE CITY COUNCIL OF THE 22 CITY OF VERNON AS FOLLOWS: 23 SECTION 1: The City Council of the City of Vernon hereby 24 finds and determines that the recitals contained hereinabove are true 25 and correct. 26 SECTION 2: The City Council of the City of Vernon hereby 27 approves and adopts the City of Vernon's "Development Planning For 28 Storm Water Management, a Manual for the Standard Urban Storm Water - 2 - V . T , 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25. 26 27 28 Mitigation Plans (SUSMPs)," a copy of which have been presented to the City Council concurrently with this resolution, and the City Council hereby orders the Program to be received and filed by the City Clerk. SECTION 3: The City Clerk of the City of Vernon shall certify to the passage of this resolution, and thereupon and thereafter the same shall be in full force and effect. APPROVED AND ADOPTED this 19th day of December, 2000. ATTEST• / y BRUCE V. MALKENHORST, City Clerk LEONIS C. MA BURG, M yor - 3 - 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 STATE OF CALIFORNIA COUNTY OF LOS ANGELES ss I, BRUCE V. MALKENHORST, City Clerk of the City of Vernon, do hereby certify that the foregoing Resolution, being Resolution No. 7683, was duly adopted by the City Council of the City of Vernon at a regular meeting of the City Council duly held on Tuesday, December 19. 2000, and thereafter was duly signed by the Mayor of the City of Vernon. BRUCE V. MALKENHORST, City Clerk . (SEAL) - 4 - SUPPORTING DOCUMENTS City of Venwn pq Devekpnent manning for dMAIM-4 " AMA %wn Kim A Manual for the Standard i Ud, tonnvvateir (SUSMPS) a Bagi S Mifigation Plans IF - i- Samuel "Kevin" Wilson, PE., L.S. Director d Community Services and Water October2000 Section 1 Introduction Page 1.1 Background........................................ ................... 1 Legal Framework ......... .........2 1.3 Standard Urban Stormwater Mitigation Plan ....................3 Section 2 Permitting and Inspection of SUSMP 2.1 General Description of Permitting & Inspection of SUSMP .................. ......4 Section 3 Standard Urban Storm Water Mitigation Plan r� 3.0 Standard Urban Storm Water Mitigation Plan for Los Angeles County and Cities in Los Angeles County ....7 Figures 2-1 Permitting & Inspection of SUSMP ............. Appendix A Source Control BMP Fact Sheets..................................A-1 Appendix B Treatment Control BMP fact Sheets A_2 Storm Water Program Urban and stormwater runoff is a serious concern, in both the dry and rainy season. Studies have shown that stormwater runoff from urban and industrial areas typically contain the same general types of pollutants that are often found in wastewater from industrial discharges. Pollutants commonly found in stormwater runoff include heavy metals, pesticides, herbicides, fertilizer, animal droppings, trash, food wastes, and synthetic organic compounds such as fuels, waste oils, solvents, lubricants, and grease. Waters that flow over streets, parking lots, construction sites and industrial facilities carry these pollutants through the storm drain network dimly to the lakes, streams and beaches of southern California. These compounds can have damaging effects on both human health and aquatic ecosystems. In addition to pollutants, the high volumes of stormwater discharged from the storm drain system in areas of rapid urbanization' have had significant impacts on aquatic ecosystems due to physical modifications such as bank erosion and widening of channels. Water Quality Assessments conducted by the Regional Water Quality Control Board (Regional Board) identified impairment of a number of water bodies in Los Angeles County. The beneficial uses of certainwater bodies specifically identified in these assessments are either impaired or threaten to be impaired. Pollutants found causing impairment include: heavy metals, coliform, enteric viruses, pesticides, nutrients, polycydic aromatic hydrocarbons, polychlorinated biphenyls, organic solvents, sediments, trash, debris, algae, scum, and odor. An epidemiological study conducted during the summer of 1995 for the Santa Monica Bay Restoration Project (SMBRP) demonstrated that there is an increased risk of acute illnesses caused by swimming near flowing storm drain outlets in Santa Monica Bay. The Regional Board therefore considers stormwater and urban runoff discharges to be significant sources of pollutants that may be causing, threatening to cause, or contributing to the impairment of the water quality and beneficial uses of the receiving water bodies in Los Angeles County. Urban runoff is considered to be one of the largest sources of pollution to the waterway and coastal areas of the United States. Locally, we see the impacts in increased health risks to swimmers near storm drains, high concentrations of toxic metals in harbor and ocean sediments, and toAcity to aquatic life. These impacts translate into losses to the County's annual tourism economy, loss of recreational resources, dramatic cost increases for cleaning up contaminated sediments and impaired function and vitality of our natural resources. in 1987, the Federal Water Pollution Control Act (also referred to as the Clean Water Act [CWA] ) was amended to provide that the discharge of pollutants to waters of the United States from stormwater is effectively prohibited, unless the discharge is in compliance with a National Pollutant Discharge Elimination System (NPDES) Permit The 1987 amendments to the CWA added Section ' 402(p) which established a framework for regulating municipal, industrial and construction stormwater discharges under the NPDES program. In California, these permits are issued through the State Water Resources Control Board (SWRCB) and the nine Regional Water Quality Control Boards. On July 15, 1996, the Regional Water Quality Control Board, Los Angeles Region (RWQCB), adopted OrderNo. 96-054. This Order is the NPDES Permit (NPDES No. CAS614001 ) for municipal stormwater and urban runoff discharges within the County of Los Angeles. As adopted :in July 1996, the requirements of Order No. 96- 054 (the "Permit") covers 85 cities and the unincorporated areas of Los Angeles County, with the exception of the portion of Los Angeles County in the Antelope Valley including the cities of Lancaster and Palmdale, and the City of Avalon. Under the Permit, the County of Los Angeles is designated as the Principal Permittee and the 85 incorporated cities as Permittees. The Principal Permittee coordinates and facilitates activities necessary to comply with the requirements of the Permit, but is not responsible for ensuring compliance of any of the Permittees. In compliance with the Permit, the Permittees, including the County, have embarked on a variety of stormwater management programs with the ultimate goal of accomplishing the requirements of the Permit and reducing the pollutants in stormwater and urban runoff. These programs are broken up into various categories of the Model Programs that were created as a requirement of the Permit. These categories are Illicit Connection/Illicit Discharge, Development Planning, Development Construction, Public Agency Activities, and Public Information and Participation_ Each Permittee is required by the Permit to have developed and implemented, by July 30,1999, programs equivalent to the Model Programs. PA One specific requirement from the Development Planning Model Program is the Standard Urban Stormwater Mitigation Plan (SUSMP). This manual serves as a guideline for compliance with this SUSMP. The SUSMP outlines the necessary Best Management Practices (BMPs) which must be incorporated into design plans for the following new developments which require discretionary approval: 1. Single-family Hillside Residences 2. 100,000 square -foot commercial development 3. Automotive repair shop 4. Retail gasoline outlet 5. Restaurants 6. Home Subdivisions with 10 to 99 housing units 7. Home Subdivisions with 100 or more housing units 8. Parking lots, 5,000 square feet or more or with 25 or more parking s spaces and potentially exposed to storm water runoff The developments projects having the following characteristics or activities may be required to address the applicable sections of the above -mentioned SUSMP when completing the project design; 1. automotive or equipment repair and/or maintenance 2. automotive or equipment washing or cleaning area(s) 3. gas station or fuel dispensing 4. outdoor material or waste handling or storage 5. chemical handling and/or storage of petroleum products, paints, solvents, concrete, or hazardous waste 6. outdoor equipment or product fabrication including welding;' cutting, sawing, metal fabrication, assembly, application of paints,, coatings, or finishes, pro -cast concrete fabrication, etc. 7. outdoor areas for equipment or machinery repair and/or maintenance 8. dry cleaning factory 9. food service 10. food processing plant 11. animal slaughtering 12. animal confinement, pet care facilities stables, kennels, etc. 13. 10 or more dwelling units 14. hillside location 3 ft Storm Water Pr --ram Permitting and Inspedon of SUSMP Any Project submitted to the City of Vernon for review and approval may be subjected to the requirements of the NPDES Permit. Development projects submitted for review and approval will be screened to determine if a SUSMP is required. All development projects which require discretionary approval and are listed in Table 2-1, will be required to submit a drainage concept and storm water quality Details of facilities and measures which mitigate impacts to water quality would then be shown down improvement plans and reviewed as part of those plans. To assist in the preparation of this plan, a SUSMP has been developed for the eight project types listed in Table 2-1. This SUSMP outlines the BMPs to be incorporated into the project design. Development projects having characteristics teristics or activities listed in Table 2-2 may be required to address the applicable sections of the above mentioned SUSMP when completing the project design. Table 2-1 Standard Urban Stormwater Mitigation Plan Y Pro'ect T Single-family Hillside Residences 100,000+ square -foot commercial development Automotive repair shop Retail gasNine outlet Restaurants Home Subdivisions with 10 to 99 housing units Home Subdivisions with 100 or more housing units Parking lots, 5,000 square feet or more or with 25 or more parking s s aces and. tentiall ex sed to storm water runoff 4 Table 2 2 Standard Urban Stormwater Mitigation Plan Characteristics & Activities Automotive or PWIpment repair and/or maintenance Automotive or equipment washing or cleaning area(s) s station or fuel dispensing outdoor material or waste handling or storacje chemical handling and/or storage of petroleum products, paints, solvents, concrete, or hazardous waste Outdoor equipment or product fabrication including welding, cutting, sawing, metal fabrication, assembly, application of paints, coatings, or finishes, pro -cast concrete fabrication, etc. outdoor areas for 2guipment or machine repair and/or maintenance dry cleaning factory food service food processi ant animal slaughtering animal confinement, Pet care facilities stables, kennels, etc. 10 or more dwelling units hiillside location Please refer to the following flow chart for your specific project permitting and inspection process. Y k FIGURE 2-1 PERMITTING AND INSPECTION OF SUSMP Submittal of Project Plans (Project amongst identified categories) Isthe Project from GEQA NO exempt En aonm al Document lNegative Declaration, MWOMed Negative Dsdamfion, or EIR Reviewed for Required Siam Water Standard BMPs DISCRETIONARY YES Review BMPs in Drainange and/or Grading Plans (site improvements) Storm Drain connection permits Regional Planning CEQA determination Discretionary or Ministerial Screen application. Check to determine if SUSMP applies YES Review Structural BMPs in Building and Site Plans (when included) Upon receiving all agency approvals permit is issued Community Services will inspect construction of BMPs MINISTERIAL NO No SUSMP Requirements Review BMPs for operating permits (when included) Ongoing inspecwn� of permitted BMPs I r, •I Ace • • - - r • a • 7 STANDARD URBAN STORM WATER MITIGATION PLAN FOR LOS ANGELES COUNTY AND CITIES IN LOS ANGELES COUNTY Find Approved — RegrorW Board Executive Officer March 8, 2000. LOS ANGELES COUNTY URBAN RUNOFF AND STORM WATER NPDES PERMIT STANDARD URBAN STORM WATER MITIGATION PLAN BACKGROUND The municipal storm water National Pollutant Dischatge Elimination System (NPDES) permit (Los Angeles County Permit) issued to Los Angeles County and 85 cities (Permittees) by the Los Angeles Regional Water Quality Control Board (Regional Board) on July 15, 1996, requires the development and implementation of a program addressing storm water Pollution issues in development planning for private projects. The same requirements are applicable to the City of Long Beach under its separate municipal storm water permit (City of Long Beach M.S4 Pen -nit), which was issued on June 30, 1999. The requirement to implement a program for development planning is based on, federal and State statutes including: Section 402 (p) of the Clean Water Act, Section 6217 of the Coastal Zone Act Reauthorization Amendments of 1990 ("CZARA"), and the California Water Code. The, Clean Water Act amendments of 1987 established a framework for regulating storm water discharges from municipal, industrial, and construction activities under the NPDES program. The primary objectives of the municipal storm water program requirements are to: 1. Effectively prohibit non -storm water discharges, and 2. Reduce the discharge of pollutants from storm water conveyance systems to the Maximum Extent Practicable (MEP statutory standard). The Standard Urban Storm Water Mitigation Plan (SUSMP) was developed as part of the municipal storm water Program to address storm water pollution from new Development and Redevelopment by the private sector. This SUSMP contains a list of the minimum required Best Management Practices (BMPs) that must be used for a designated project. Additional BMPs may be required by ordinance or code adopted by the Permittee and applied generally or on a case by case basis. The Permittees are required to adopt the requirements set herein in their own SUSMP. Developers must incorporate appropriate SUSMP requirements into their project plans. Each Permittee will approve the project plan as part of the development plan approval process and prior to issuing building and grading permits for the projects covered by the SUSMP requirements. Fmal Approved —Regional Board Executive OfficerPage 2 of 25 AA-1, a lnnn All discretionary development and redevelopment projects that fall into one of the following categories are subs to these SUSMPs. These categories are: - • Single -Family Hillside Residences 100.000 Square Foot Commercial Developments • Automotive Repair Shops • Retail Gasoline Outlets • Restaurants • Home Subdivision with 10 to 99 housing units 0 Home Subdivision with 100 or more housing units Parking lots 5,000 square feet or more or with 25.or more parking spaces and potentially exposed to storm water runoff The City of Long Beach permit requires SUSMP for the following categories only: (i) 10-99 home subdivisions; (0)100 or more subdivisions; (ii)100,000 or more square foot commercial devebpments; and (iv) Projects located adjacent to or discharging to environmentally sensitive areas. For the remaining five categories, equivalent requirements have been included directly in or are expected to be developed shortly under the City of Long Beady Stone Water Management Plan. Permittees shall amend codes and promulgate ordinances not later than January 15, 2001 to give legal effects to the SUSMP requirements. The SUSMP requirements for projects identified herein shall take effect not later than February 15, 2001. DEFINITIONS "100,000 Square Foot Commercial Development" means any commercial development that creates at least 100,000 of impermeable area, including parking areas. "Automotive Repair Shop" means a facility that is categorised in any one of the following Standard Industrial Classification (SIC) codes: 5013, 5014, 5541, 7532- 7534, or 7536-7539. Y "Best Management Practices (BMP)" means any program, technology, process, siting criteria, operational methods or measures, or engineered systems, which when implemented prevent, control, remove, or reduce pollution. "Commercial DevelopmenC—means any development on private land that is not heavy industrial or residential. The category includes, but is not limited to: hospitals, laboratories and other medical facilities, educational institutions,recreational facilities, plant nurseries, multi -apartment buildings, car wash facilities, mini -malls and other business complexes, shopping malls, hotels, office buildings, public warehouses and other light industrial complexes. Final PAGE 3 OF 25 AWv-d-Regional Board Executive OHae, Marc, 8, 2000 "Directly Connected Impervious Area (DCIA)" means the area covered by a building, impermeable pavement, and/or other impervious surfaces, which drain directly into the storm drain without first flowing across permeable land area (e.g. lawn). "Discretionary Project" means a project which requires the exercise of judgement,or deliberation when the public agency or public body decides to approve or disapprove a particular activity, as distinguished from situations where the public agency or body merely has to determine whether there has been conformity with applicable statues, ordinances, or regulations. "Greater than (>) 9 unit home subdivision" means any subdivision being developed for 10 or more 10 single-family or multi family dwellings units. "Hillside" means property located in an area with known erosive soil conditions, where the development contemplates grading on any natural slope that is twenty-five percent or greater. "Infiltration" --means the downward entry of water into the surface of the soil. "New Development" means land disturbing activities; structural development, including construction or installation of a building or structure, creation of impervious surfaces; and land subdivisions. "Parking Lot" means land area or fac city for the temporary parking or storage of motor vehicles used personally, for business or for commerce with a lot size of 5,000 square feet or more, or with 25 or more parking spaces. "Redevelopment' means on an already developed site; the creation or addition of at least 5,000 square feet of impervious surfaces. Redevelopment includes, but is not limited. to: the expansion of a building footprint or addition or replacement of a structure; structural development including an increase in gross floor area and/or exterior construction or remodeling; replacement of impervious surface that is not Part of a routine maintenance activity; and land disturbing activities related with structural or impervious surfaces. Where redevelopment in an increase of less than fifty percent of the impervious surfaces of a previously existing development, and the existing development was not subject to these SUSMPs, the Design Standards apply only to the addition, and not the entire development. Rid PAGE 4 OF 25 APPrmed-Regionai Board ExectAve OR,-, Mary h 8, 2000 "Restaurant" means a stand-alone facility that sells prepared foods and drinks for consumption, including stationary lunch counters and refreshment stands selling Prepared foods and drinks for immediate consumption. (SIC code 5812). "Retail Gasoline Outlet" means any facility engaged in selling gasoline and lubricating oils. "Source Control BMP" means any schedules of activities, prohibitions of practices, maintenance procedures, managerial practices or operational practices that aim to prevent storm.water pollution by reducing the potential for contamination at the source of pollution. "Storm Event" means a rainfall event that produces more than 0.1 inch of precipitation and that, which is separated from the previous storm event by at least 72 hours of dry weather. "Structural BMP" means any structural facility designed and constructed to mitigate the adverse impacts of storm water and urban runoff pollution. (e.g. canopy, structural enclosure). The category may include both Treatment Control BMPs and Source Control BMPs. "Treatment" means the application of engineered systems that use physical, chemical, or biological processes to remove pollutants. Such processes include, but are not lirri ted to, filtration, gravity settling, media adsorption, biodegradation, biological uptake, chemical oxidation and UV radiation. 'Treatment Control BMP" means 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. CONFLICTS WITH LOCAL PRACTICES Where provisions of the SUSMP requirements conflict with established local codes, (e.g., specific language of signage used on storm drain stenciling), the Perrnittee may continue the local practice and modify the SUSMP to be consistent with the code, except that to the extent that the standards in the SUSMP are more stringent than those under local codes, such more stringent standards shall apply. SUSMP PROVISIONS APPLICABLE TO ALL CATEGORIES FMW Approved — Regrond Board Executive Officer Page 5 of 25 Mamh 8, 2000 REQUIREMENTS Post -development peak storm water runoff discharge rates shall not exceed the estimated pre -development rate for developments where the increased peak storm water discharge rate will result in increased potential for downstream erosion. If applicable, the following items are required and must be implemented in the site layout during the subdivision design and approval process, consistent with applicable General Plan and Local Area Plan policies: • Concentrate or cluster Development on portions of a site while leaving the remaining land in a natural undisturbed condition. • Limit clearing and grading of native vegetation at a site to the minimum amount needed to build lots, allow access, and provide fire protection. • Ma)dmize trees and other vegetation at each site by planting additional vegetation, clustering tree areas, and promoting the use of native and/or drought tolerant plants. • Promote natural vegetation by using parking lot islands and other landscaped areas. • Preserve riparian areas and wetlands. Storm water runoff from a site has the potential to contribute oil and grease, suspended solids, metals, gasoline, pesticides, and pathogens to the storm water conveyance system. The development must be designed so as to minimize, to the maximum extent Practicable, the introduction of pollutants of concern that may result in significant impacts, generated from site runoff of directly .connected impervious areas (DCIA), to the storm water conveyance system as approved by the building official. Pollutants of concern, consist of any pollutants that exhibit one or more of the following characteristics: current loadings or historic deposits of the pollutant are impacting the beneficial uses of a receiving water, elevated levels of the pollutant are found in sediments of a receiving water and/or have the potential to bioaccumulate in organisms therein, or the detectable inputs of the pollutant are at a concentrations or loads considered potentially toxic to humans and/or flora and fauna. In meeting this specific requirement, "minimization of the pollutants of concern" will require the incorporation of a BMP or combination of BMPs best suited. to maximize the reduction of pollutant loadings in that runoff to the Maximum Extent Practicable. Those BMPs best suited for that purpose are those listed in the California Storm Water Best Management Practices Handbooks; Caltrans Storm Water Quality Handbook: Planning and Design Staff Guide; Manual for Storm Water Management in Washington State; rmat Approved - Regional Board Executive officer March 8, 2000 Page 6 of 25 The Maryland Stormwater Design Manual; Florida Development Manual., A Guide to Sound Land and Water Management, Denver Urban Storm Drainage Criteria Manual, Volume 3 — Best Management Practices and Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters , USEPA Report No. EPA-840-B-92-002, -as "likely to have significant impact" beneficial to water quality for targeted pollutants that are of concern at the site in question. However, it is possible that a combination of BMPs not so designated, may in a particular circumstance, be better suited to maximize the reduction of the pollutants. Examples of BMPs that can be used for minimizing the introduction of pollutants of concern generated from site runoff are identified in Table 2. Any BMP not specifically approved by the Regional Board in Resolution No. 99-03, "Approving Best Management Practices for Municipal Storm Water and Urban Runoff Programs in Los Angeles County", for development planning may be used if they have been recommended in one of the above references. Project plans must include BMPs consistent with local des and ordinances and the SUSMP to decrease the potential of slopes and/or channels from eroding and impacting storm water runoff. • Convey runoff safely from the tops of slopes and stabilize disturbed slopes. • Utilize natural drainage systems to the maximum extent practicable • Control or reduce or eliminate flow to natural drainage systems to the maximum extent practicable • Stabilize permanent channel crossings. • Vegetate slopes with native or drought tolerant vegetation. • Install energy dissipaters, such as riprap, at the outlets of new storm drains, culverts, conduits, or channels that enter unlined channels in accordance with applicable specifications to minimize erosion, with the approval of all agencies with jurisdiction, e.g., the U.S. Army Corps of Engineers and the California Department of Fish and Game Storm drain stencils are highly visible source controls that are typically placed directly adjacent to storm drain inlets. The stencil contains a brief statement that prohibits the dumping of improper materials into the storm water conveyance system. Graphical icons, either illustrating anti -dumping symbols or images .of receiving water fauna, are effective supplements to the anti -dumping message. • All storm drain inlets and catch basins within the project area must be Fmal APPOled — Regional Board Executive officer Page 7 of 25 Mom+, A wn S stenciled with prohibitive language (such as: "NO DUMPING -- DRAINS TO OCEAN") and/or graphical icons to discourage illegal dumping. • Signs and prohibitive language and/or graphical icons, which prohibit illegal dumping, must be posted at public access points along channels and creeks within the project area. • Legibility of stencils and signs must be maintained. Outdoor material storage areas refer to storage areas or storage facilities solely for the storage of materials. Improper storage of materials outdoors may provide an opportunity- for toxic compounds, oil and grease, heavy metals, nutrients, suspended solids, and other pollutants to enter the storm water conveyance system. Where proposed project plans include outdoor areas for storage of materials that may contribute pollutants to the storm water conveyance system, the following Structural or Treatment BMPs are required: . • Materials with the potential to contaminate storm water must be: (1) placed in an enclosure such as, but not limited to, a cabinet, shed, or similar structure that prevents contact_ with runoff or spillage to the storm water conveyance system; or (2) protected by secondary containment structures such as berms, dikes, or curbs. The storage area must be paved and sufficiently impervious to contain leaks and spills. The storage area must have a roof or awning to minimize collection of storm water within the secondary containment area. A trash storage area refers to an area where a trash receptacle or receptacles are located for use as a repository for solid wastes. Loose trash and debris can be easily transported by the forces of water or wind into nearby storm drain inlets, channels, and/or creeks. All trash container areas must meet the following Structural or Treatment Control BMP requirements (individual single family residences are exempt from these requirements): • Trash container areas must have drainage from adjoining roofs and pavement diverted around the area(s). • Trash container areas must be screened or walled to prevent off -site transport of trash. rmal APPrOved — Regional Board Executive ollim Page 8 of 25 Improper maintenance is one of the most common reasons why water quality controls will not function as designed or which may cause the system to fail entirely. it is important to consider who will be responsible for maintenance of a permanent BMP, and what equipment is required to perform the maintenance properly. As part of project review, if a project applicant has included or is required to include, Structural or Treatment Control BMPs in project plans, the Permittee shall require that the applicant provide verification of maintenance provisions through such means as may be appropriate, including, but not limited to legal agreements, covenants, CEQA mitigation requirements and/or Conditional Use Permits. For all properties, the verification will include the developer's signed statement, as part of the project application, accepting responsibility for all structural and treatment control BMP maintenance until the time the property is transferred and, where applicable, a signed agreement from the public entity assuming responsibility for Structural or Treatment Control BMP maintenance. The transfer of property to a private or public owner must have conditions requiring the recipient to assume responsibility for maintenance of any Structural or Treatment Control BMP to be included in the sales or lease agreement for that property, and will be the owner's responsibility. The condition of transfer shall include a provision that the property owners conduct maintenance inspection of all Structural or Treatment Control BMPs at least once a year and retain proof of inspection. For residential properties where the Structural or Treatment Control BMPs are located within a common area which will be maintained by a homeowner's association, language regarding the responsibility for maintenance must be included in the projects conditions, covenants and restrictions (CC&Rs). Printed educational materials will be required to accompany the first deed transfer to highlight the existence of the requirement and to provide information on what storm water management facilities are present, signs that maintenance is needed, how the necessary maintenance can be performed, and assistance that the"Permittee can provide. The transfer of this information shall also be required with any subsequent sale of the property. If Structural or Treatment Control BMPs are located within a public area proposed for transfer, they will be the responsibility of the developer until they are accepted for transfer by the County or other appropriate public agency. Structural or Treatment Control BMPs proposed for transfer must meet design standards adopted by the public entity for the BMP installed and should be approved by the County or other appropriate public agency prior to its installation. Structural or Treatment control BMPs selected for use at any project covered by this fii Approved — Regional Board Executive Officer Page 9 of 25 Myrrh R 9nnn SUSMP shall meet the design standards of this Section unless specifically exempted. Post -construction Structural or Treatment Control BMPs shall be designed to: A. mitigate (infiltrate or treat) storm water runoff from either: 1. the 85"' percentile 24hour runoff event determined as the maximized capture storm water volume for the area, from the formula recommended in Urban Runoff Quality Management, WEF Manual of Practice No. 231ASCE Manual of Practice No. 87, (1998), or 2. the volume of annual runoff based on unit basin storage water quality volume, to achieve 80 percent or more volume treatment by the method recommended in California Stormwater Best Management Practices Handbook — lndustriaU Commercial, (1993), or I thevolumeof runoff produced from a 0.75 inch storm event, prior to its discharge to a storm water conveyance system, or 4. the volume of runoff produced from a historical -record based reference 24-hour rainfall criterion for "treatment° (0.75 inch average for the Los Angeles County area) that achieves approximately the same reduction in pollutant loads achieved by the 8e percentile 24hour runoff event, AND fi. control peak flow discharge to provide stream channel and over bank flood Protection, based on flow design criteria selected by the local agency. %mited Exclusion Restaurants, where the land area for development or redevelopment is less than 5,000 square feet, are excluded from the numerical Structural or Treatment Control BMP design standard requirement only. Retail Gasoline Outlets REQUIREMENTS Fuld Page 10 of 25 Approved - Regional Board Executive Officer AA-4, 0 -)nnn A. 100,000 SQUARE FOOT COMMERCIAL DEVELOPMENTS Loading/unloading dock areas have the potential for material spills to be quickly transported to the storm water conveyance system. To minimize this potential, the following design criteria are required: • Cover loading dock areas or ,design drainage to minimize run-on and runoff of storm water. Direct connections to storm drains from depressed loading docks (truck wells) are prohibited. Oil and grease, solvents, car battery acid, coolant and gasoline from the repair/maintenance bays can negatively impact storm water if allowed to come into contact with storm water runoff. Therefore, design plans for repair bays must include the following: Repairimaintenance bays must be indoors or designed in such a way that doesn't allow storm water runon or contact with storm water runoff. Design a repair/maintenance bay drainage system to capture all washwater, leaks and spills. Connect drains to a sump for collection and disposal. Direct connection of the repair/maintenance bays to the storm drain system is prohibited. if required by local jurisdiction, obtain an Industrial Waste Discharge Permit. The activity of vehicle/equipment washing/steam cleaning- has the potential to contribute metals, oil and grease, solvents, phosphates, and suspended solids to the storm water conveyance system. Include in the project plans an area for washing/steam cleaning of vehicles and equipment. The area in the site design must be: • Self-contained and/ or covered, equipped with a clarifier, or other pretreatment facility, and properly connected to a sanitary sewer. B. RESTAURANTS The activity of outdoor equipmenttaccessory washing/steam cleaning has the potential to contribute metals, oil and grease, solvents, phosphates, and suspended solids to the storm water conveyance system. Include in the project plans an area for the FkW P Approved -Regional Board Executive Officer age 19 of 25 Marsh 8, 2000 washing/steam cleaning of equipment and accessories. This area must be: • Self-contained, equipped with a grease trap, and properly connected to a sanitary sewer. • If the wash area is to be located outdoors, it must be covered, paved, have secondary containment, and be connected to the sanitary sewer. C. RETAIL GASOLINE OUTLETS Fueling areas have the potential to contribute oil and grease, solvents, car battery acid, coolant and gasoline to the storm water conveyance system. The project plans must include the following BMPs: • The fuel dispensing area must be covered with an overhanging ref structure Or canopy. The canopy's minimum dimensions must be equal to or greater than the area within the grade break. The canopy must not drain onto the fuel dispensing area, and the canopy downspouts must be routed to prevent drainage across the fueling area. • The fuel dispensing area must be paved with Portland cement concrete (or equivalent smooth impervious surface), and the use of asphalt concrete shall be prohibited. • The fuel dispensing area must have a 2% to 4% slope to prevent ponding, and must be separated from the rest of the site by a grade break that prevents run-on of stone water to the extent practicable. • At a minimum,. the concrete fuel dispensing area must extend 6.5 feet (2.0 meters) from the comer of each fuel dispenses, or the length at which the tease and nozzle assembly may be operated plus 1 foot (0.3 meter), whichever is less. O. AUTOMOTIVE REPAIR SHOPS Fueling areas have the potential to contribute oil and grease, solvents, car battery acid, coolant and gasoline to the storm water conveyance system. Therefore, design plans, which include fueling areas, must contain the following: • The fuel dispensing area should be covered with an overhanging roof structure or canopy. The cover's minimum dimensions must be equal to or greater than the area within the grade break. The cover must not drain onto the fuel dispensing area and the downspouts must be routed to prevent drainage across the fueling area. • The fuel dispensing areas must be paved with Portland cement concrete (or equivalent smooth impervious surface), and the use of asphalt concrete shall be prohibited. • The fuel dispensing area must have a 2% to 4% slope to prevent ponding, and must be separated from the rest of the site by a grade break that prevents run-on of storm water. • At a minimum, the concrete fuel dispensing area must extend 6.5 feet (2.0 meters) from the corner of each fuel dispenser, or the length at which the hose and nozzle assembly may be operated plus 1 foot (0.3 meter), whichever is less. Firial App med _ Regional Board Executive Of m Page 12 of 25 March 9. Wn Olt and grease, solvents, car battery acid, coolant and gasoline from the repair/maintenance bays can negatively impact storm water if allowed to come into contact with storm water runoff. Therefore, design plans for repair bays must include the following: • Repair/maintenance bays must be indoors or designed in such a way that doesn't allow storm water run-on or contact with storm water runoff. • Design a repair/maintenance bay drainage system to capture all wash -water, leaks and spills. Connect drains to a sump for collection and disposal. Direct connection of the repair/maintenance bays to the storm drain system is prohibited. If required by local jurisdiction, obtain an Industrial Waste Discharge Permit - ii The .activity of vehicle/equipment washing/steam cleaning has the potential to contribute metals, oil and grease, solvents, phosphates, and suspended solids to the storm water conveyance system. Include in the project plans an area for washing/steam cleaning of vehicles and equipment. This area must be: • Self-contained and/or covered, equipped with a clarifier, or other pretreatment facility, and properly connected to a sanitary sewer or to a permitted disposal facility. Loading/unloading dock areas have the potential for material spills to be quickly transported to the storm water conveyance system. To minimize this potential, the following design criteria are required: y: Cover loading dock areas or design drainage to minimize run-on and runoff of storm water. • Direct connections to storm drains from depressed loading docks (truck wells) are prohibited. E. PARKING LOTS CAIMIlu rutz> uuruain pollutants such as heavy metals, oil and grease, and polycyclic aromatic hydrocarbons that are deposited on parking lot surfaces by motor -vehicles. These pollutants are directly transported to surface waters. To minimize the offsite transport of pollutants, the following design criteria are required: Final Approved — Regional Board Executive Officer SA-1.0 7nnn Page 13 of 25 • Reduce impervious land coverage of parking areas • Infiltrate runoff before it reaches storm drain system. • Treat runoff before it reaches storm drain system Parking lots may accumulate oil, grease, and water insoluble hydrocarbons from vehicle drippings and engine system leaks. Treat to remove oil and petroleum hydrocarbons at parking lots that are heavily used (e.g. fast food Outlets, lots with 25 or more parking spaces , sports event parking_ lots, shopping mails, grocery stores, discount warehouse stores) Ensure adequate operation and maintenance of treatmentsystems removal, and system foulingand particularly sludge and oil Plugging prevention control `'l a f 'e.' a 3" A Permittee may, through adoption of an ordinance or code incorporating the treatment requirements of the SUSMP, provide for a waiver from the requirement if impracticability for a specific property can be established. A waiver of impracticability shall be granted only when all other Structural or Treatment Control BMPs have been considered and rejected as infeasible. Recognized situations of impracticability include, (i) extreme limitations of space for treatment on a redevelopment - project, (H) unfavorable or unstable soil conditions at a site to attempt infiltration, and (ii) risk of ground water contamination because a known unconfined aquifer lies beneath the land surface or an existing or potential underground source of drinking water is fens than 10 feet from the soil surface. Any other justification for impracticability must be separately petitioned by the Permittee and submitted to the -Regional Board for consideration. The Regional Board may consider approval of the waiver justification or (pay delegate the authority to approve a class of waiver justifications to the Regional Board Executive Officer. The supplementary waiver justification becomes recognized and effective only after approval by the Regional Board or the Regional Board Executive Officer. A waiver granted by a Permittee to any development or redevelopment project may be revoked by the Regional Board Executive Officer for cause and with proper. notice upon petition. armed — Regional Board Exec„ ive oft, Page 14 of 25 March s, 2WO Three factors significantly influence the potential for storm water to contaminate ground water. They are (i) pollutant mobility, (ii) pollutant abundance in storm water, (iii) and soluble fraction of pollutant. The risk of contamination of groundwater may be reduced by pretreatment of storm water. A discussion of limitations and guidance for infiltration practices is contained in, Potential Groundwater Contamination frr�m, Intentional and Non -Intentional Stormwater Infiltration, Report No. EPA1600/R-941051, USEPA (1994). In addition, the distance of the groundwater table from the infiltration BMP may also be a factor determining the risk of contamination. A water table distance separation of ten feet depth in California presumptively poses negligible risk for storm water not associated with industrial activity or high vehicular traffic. Infiltration BMPs are not recommended for areas of industrial activity'or areas subject to high vehicular traffic (25,000 or greater average daily traffic (ADT) on main roadway or 15,000 or more ADT on any intersecting roadway) unless appropriate pretreatment is provided to ensure groundwater is protected and the infiltration .BMP is not rendered ineffective by overload. In lieu of conducting detailed BMP review to verify Structural or Treatment Control BMPs adequacy, a Permittee may elect to accept a signed certification from a Civil Engineer or a Licensed Architect registered in the State of California, that the plan meets the criteria established herein. The Permittee is encouraged to verify that certifying person(s) have been trained on BMP design for water quality; not more than two years prior to the signature date. Training conducted by an organization with storm water BMP design expertise (e.g., a University, American Society of Civil Engineers, American Society of Landscape Architects, American Public Works Association, or the California Water Environment Association) may be considered qualifying. SUGGESTED RESOURCES TABLE 1 HOW TO GET A COPY FkW Approved — Regional Board Executive Officer March 8, 2000 Page 15 of 25 Start at the Source (1999) by Bay Area Stormwater Bay Area Stormwater Management Agencies Management Agencies Association Association Detailed discussion of 2101 Webster Street permeable pavements and Suite 500 alternative driveway designs presented. Oakland, CA 510-286-1255 Design of Storrnwater Filtering. Systems (1996) by Center for Watershed Protection Richard A. Claytor and Thomas R. Schuler 8391 Main Street Presents detailed engineering Ellicott City, MD 21043 g ng guidance on ten 410-461-8323 different storm water -filtering systems. Better Site A Handbook for Changing Center #or Watershed Protection Development Rues in Your Community (1998) 8391 Main Street Ellicott City, MD 21043 Presents guidance for different model development 410-461-8323 alternatives. Design Manual for Use of Bioretention in Prince George's County Sformwater Management (1993) Watershed Protection' Branch Pla Presents guidance for designing bioretention Lando Per, Mpe p 0785 ce, Suite 600 facilities, ..r......,—, -allotarianoe ana management of Stonnwater Management (1997) Provides a thorough look at stormwater practices including, planning and design considerations, programmatic and regulatory aspects, maintenance considerations, and costs. California Storm Water Best Management Practices Handbooks (1993) for Construction Activity, Municipal, and Industrial/Commercial Presents a description of a large variety of Structural BMPs, Treatment Control, BMPs and Source Control BMPs SUGGESTED RESOURCES vvazersnea management Institute, Inc. 410 White Oak Drive . Crawfordville,-FL 32327 850-926-5310 Los Angeles County Department of Public Works Cashiers Office 900 S. Fremont Avenue Alhambra, CA 91803 - 626-458-6959 TABLE 1 (Continued) HOW TO GET A COPY r=mal AWO"d - Regional Board Executive offim Page 16 of 25 March 8, 2000 Secaond Nature: Adapting LA-s Landscape for Tree People Sustainable Living (1999) by Tree People 12601 Muilholland Drive Detailed discussion of BMP designs Beverly Hills, CA 90210 conserve water, improve water quality andt to 818-7534600 (?) achieve flood protection. '-""uu ueveropment Manual. A Guide to Sound Land and Water Management (1988) Presents detailed guidance for designing BMPs .murmwarer Management in Washington State (1999) Vols. 1-5 Presents detailed guidance on BMP design for new development and construction. Florida Department of the Environr Blairstone Road, Mail Station 3570 Tallahassee, FL 32399 850-921-9472 State of Washington Department of Ecology P.O. Box 798 Olympia, WA 98507-0798 360-407-7529 MarylandStonnwaterDesign Wanuar(1999) Mar yland Department of the Environment Hhw Presents guidance for designing storm water BMPs Bal�timore,MD 21224ay 410-631-3000 P VAUS n+vnparnt Source Book— Online Module (1998)wuvw.t a2;;book org Presents BMP design and guidance information on-line Urban Storm Drainage, Criteda Manua A Best Management Practices (1999) Presents guidance for designing BMPs Texas Statewide Storm Water Quality Task F North Central Texas Council of Governments 616 Six Flags Drive Arlington, TX 76005 817-695-9150 — Volume Urban Drainage and Flood Control Di 2480 West 26th Avenue, Suite 156-8 Denver, CO 80211 303-455-6277 "-.� •-aparwip'"g management Measures for Sams of Nonpoint Pollution in Coastal Waters (1993) Report No. EPA--840-8-g2-002. Provides an overview of, planning and design considerations, programmatic and regulatory aspects, maintenance considerations, and costs. National Technical Information Service U.S. Department of Commerce Springfield, VA 22161 800-553-6847 r National Stommwater Best Management Practices American Society of Civil Engineers (BMP) Database, Version 1.0 1801 Alexander Bell Drive Reston, VA Provides data on performance and evaluation of 703 296-6000191 storm water BMPs Final AWoved - Regional Board Ewuee off,,, Page 17 of 25 March a. 2000 SUGGESTED RESOURCES HOW TO GET A COPY Caltrafl Storm Water Quality Handbook Planning and Design Staff Guide (Best Management Practices Handbooks (1998) California Department of Transportation P.O. Box 942874 Sacramento, CA 94274-Ml alf"SZ3-2975 Presents guidance for design of storm water BMPs Fmal Approved — Regional Board Executive officer March 8. 2000 Page 18 of 25 TABLE 2 EXAMPLE BEST MANAGEMENT PRACTICES (BMPs) The following are examples of BMPs that can be used for minimizing the introduction of pollutants of concern that may result in significant impacts, generated from site runoff to the storm water conveyance system. (See Table 1: Suggested Resources for additional sources of information): • Provide reduced width sidewalks and incorporate landscaped buffer areas between sidewalks and streets. However, sidewalk widths must still comply with regulations for the Americans with Disabilities Act and other life safety. requirements. • Design residential streets for the minimum required pavement widths needed to comply with all zoning and applicable ordinances to support travel lanes; on -street parking; emergency, maintenance, and service vehicle access; sidewalks; and vegetated open channels. • Comply with all zoning and applicable, ordinances to minimize the number of residential street cul-de-sacs and incorporate landscaped areas to reduce their impervious cover. The radius of cul-de-sacs should be the minimum required to accommodate emergency and maintenance vehicles. Alternative turnarounds should be considered. • Use permeable materials for private sidewalks, driveways, parking lots, or interior roadway surfaces (examples: hybrid lots, parking groves, permeable overflow parking, etc.). • Use open space development that incorporates smaller lot sizes. • 'Reduce building density. • Comply with all -zoning and applicable ordinances to reduce overall lot imperviousness by promoting alternative driveway surfaces and shared driveways that connect two or more homes together. • Comply with all zoning and applicable ordinances to reduce the overall imperviousness associated with parking lots by providing compact car spaces, minimizing stall dimensions, incorporating efficient parking lanes, and using pervious materials in spillover parking areas. • Direct rooftop runoff to pervious areas such as yards, open channels, or vegetated areas, and avoid routing rooftop runoff to the roadway or the storm water conveyance system. • Vegetated swales and strips • Extended/dry detention basins • Infiltration basin • Infiltration trenches r • Wet ponds . • Constructed wetlands • Oil/Water separators • Catch basin inserts • Continuous flow deflection/ separation systems • Storm drain inserts • Media filtration • Bioretention facility • Dry -wells • Cisterns • Foundation planting • Catch basin screens • Normal flow storage/ separation systems • Clarifiers • Filtration systems • Primary waste water treatment systems FkW Awed- Region+ Board Executive officer Page 19 of 25 March 8. 20DO TABLE 3 HABITAT PROTECTION IN THE LOS ANGELES COUNTY AREA Agency: State Water Resources Control Board Designation: Areas of Significant Biological Significance (ASBS) finiti n: Areas designated by the State Water Resources Control Board as requiring protection of species or biological communities to the extent that alteration of natural water quality is undesirable. Affected Area: (See Table 1 & Figure 2) Agency: Los Angeles County Department of Regional Planning Designation: Significant Ecological Areas (SEA) Definitions: Significant Ecological Areas (SEAS) are areas that have been identified by the Los Angeles County General Plan as containing unique or unusual species assemblages, or areas of habitat that are rapidly declining in the Los Angeles County. The SEAS were established to protect a special or sometimes unique collection of habitats and species from loss due to encroachment and human disturbances. However, SEAS are not intended to function as isolated preservation areas. Affected Areas: (See Table A & Figure 1) Agency: California Department of Fish & Game Designation: Natural Communities Conservation Plan Region (NCCP) finition: Identifies and provides for the regional or area wide protection and perpetuation of natural wildlife diversity, while allowing compatible and appropriate development and growth. The goal of the program is to protect sufficient resources in regional preserves to assure the survival of the ecosystem and, at the same time, permit compatible uses of less sensitive land. Affected Area: (See Table 1 & Figure 3) t=mal Approved — Regional Board Executive Officer Page 20 of 25 March 8. 2000 TABLE 3 A HABITAT PROTECTION IN LOS ANGELES COUNTY AREA1 Figure 1 AFFECTED AREA DESIGNATION DESIGNATING AGENCY 1. Malibu Coastline SEA LACDRP 2. Point Dume SEA LACDRP 3. Zuma Canyon SEA LACDRP 4. Upper La Sierra Canyon SEA LACDRP 5. Malibu Canyon and Lagoon SEA LACDRP 5. Malibu Creek State Park Buffer Area SEA LACDRP 6. Las Virgenes SEA LACDRP 7. Hepatic Gulch SEA LACDRP 9. Cold Creek SEA LACDRP 10. Tuna Canyon SEA LACDRP 11. Temescal-Rustic-Sullivan Canyons SEA LACDRP 12. Palo Comado Canyon SEA LACDRP 13. Chatsworth Reservior SEA LACDRP 14. Simi Hills SEA LACDRP 15. Tonner Canyon/Chino Hills SEA LACDRP 16. Buzzard Peak/ San Jose Hills SEA LACDRP 17. Powder Canyon/Punte Hills SEA LACDRP 18. Way Hills SEA LACDRP 19. San Francisquito Canyon SEA LACDRP 20. Santa Susana Mountains SEA LACDRP 21. Santa Susana Pass SEA LACDRP 22. Santa Fe Dam Floodpiain SEA LACDRP 23. Santa Clara River SEA LACDRP 24. Tujunga Valley/HansenDam SEA LACDRP 25. San Dimas Canyon SEA LACDRP 26. San Antonio Canyon Mouth SEA LACDRP 27. Portuguese Bend Landslide SEA LACDRP 28. El Segundo Dunes SEA LACDRP 29. Baliona Creek SEA LACDRP 30. Alamitos Bay SEA LACDRP 31. Roiling Hills Canyons SEA LACDRP 32. Agua Amarga Canyon SEA LACDRP 33. Terminal Island SEA LACDRP 34. Palos Verdes Peninsula Coastline SEA LACDRP 35. Harbor Lake Regional Park SEA LACDRP 36. Madrona Marsh SEA LACDRP 37. Griffith Park SEA LACDRP 39. Encino Reservoir SEA LACDRP 40. Verdugo Mountains SEA LACDRP 1 This list is a compilation of data from the Department of Fish & Game, State Water Resources Control Board, and the Los Angeles County Department of Regional Planning as of February 29, 2000. Areas in this may changes, as area are added or deleted by the designating agencies. Final Approved - Regional Board Executive Officer Page 21 of 25 AFFECTED AREA 42. Whittier Narrows Dam County Recreation Area 43. Rio Hondo College Wildlife Santuary 44. Sycamore and Turnbull Canyons 45. Dudleya Densiflora Population 62. Galium Grande Population 63. Lyon Canyon 64. Valley Oaks Savannah, Newhall F119.2 Point Dume to Latigo Point Fig-3 Palos Verdes Peninsula DESIGNATION DESIGNATING AGENCY SEA LACDRP SEA LACDRP SEA LACDRP SEA LACDRP SEA LACDRP SEA LACDRP SEA LACDRP ASBS SWRCB NCCP DFG Fbial Approved - Regional Board Executive officer wash A )Ann Page 22 of 25 Find Approved - Regional Board Executive 0lfCer March s, 2000 Page 23 of 25 C) 1*1 FIGURE 2 t; I\ J 43 Final Approved — Regional Board Executive officer March 8, 2000 Page 24 of 25 I FIGURE 3 Rial Approved — Regional Board Executive officer March 8, 2000 Page 25 of 25 0 I CfItY 4* VEWMM - •I•A """I• L Source Control BMP Fact Sheet A-1 ACTIVITY; NO N-SMRM WATER DISCHARGES TO DRAINS _"•� -ice �' ... .... .._ �n ti^,.:�,: ,:ti`����: �<,: DESCRIPTION Eliminate non -storm water disc arges to the storm water collection system. Non -stoma water discharges may include: ',process wastewaters, coolie waters, wash w sanitary wastewater. g titers, and APPROACH The following approaches may be used to identify non -storm water discharges: Inspection f The easiest method is inspect each discharge point during dry weather. - Keep in mind that drainage from a storm event can continue for three days or more and groundwater slay infiltrate the underground storm water collection system. l Piling Schematic Review - The piping schematic is a map of pipes and drainage systems used to carry wastewater, cooling water. sanitary wastes, etc. - A review of the "as -built" piping schematic is a way to determine if there are any connections to the storm water collection system. Inspect the Path of floor drains in older buildings. • Smoke Testing Smoke testing of wastewater and storm water collection systems is used to detect connections between the two systems, - During dry weather the storm water collection system is filled with smoke and then traced to sources- The appearance of smoke at the base of a toilet indicates that there may be a connection between the sanitary and the storm water system. • Dye Testing AA dye test can be performed by simply releasing a dye into either your sanitary or Process wastewater system and examining the discharge points from the storm water collection system for discoloration. REQUIREMENTS Costs (Capital, O&M) • Can be difficult to locate illicit connections especially if there is infiltration. groundwater LIMITATIONS • hay facilities do not have acc uume, up -to -daze schematic drawings. TV and visual insPections can identify illicit connections to the storm sewer, but further testing is sometimes required (e.g. dye, smoke) to identify sources. Applications Menufactur/ng Material Handling Vehic% Ms/ntenence Construction Commerz/a/ Activ/ties Roadiweys Targeted Constituents O sediment Nutrients ! Heavy Metals ! Toxic Materiels Floatable Materials ! Oxygen Demand- ing Substances O// do Grease ! Bacteria & Vw=. s1:2ant Jmpad 0 PrvbaWo Low or Unknown lmpaet Implementation Requirements Q Capital Costs O OEM Costs 0 Maintenance Q Training ! High Q Low sci Best Manaaerrin Industrial Handbook 4-2 March, 1993 Additional Information— Non -Storm Water Discharges to Drains Facilities subject to storm water permit requirements must include a certification that the storm water collection system bas been listed or evaluated for the presence of non -storm water discharges. The State's General Industrial Storm Water Permit requires that non -storm water discharges be eliminated prior to implementation of the facility's SWPPP. Non -storm water discharges to the storm water collection system may include any water used directly in the manufactur- ing process (process wastewater), air conditioning condensate and coolant, non -contact cooling water, cooling equipment condensate. outdoor secondary containment water, vehicle and equipment wash water, sink and drinking fountain wastewater, sanitary wastes, or other wastewaters. Table 4.1 presents disposal option information for specific types of wastewaters. To ensure that the storm water system discharge contains only storm water, industry should: Locate discharges to the municinal storm sewer system or waters of the United Stares from the industrial storm sewer system from: - "as -built" pipeline schematics, and visual observation (walk boundary of plant site). ' Locate and evaluate all discharges to the indtistrial storm sewer system (including wet weather flows) from: - -as-built" pipeline schematics, - visual observation, - dye tests, - TV camera, - chemical field test kits, and - smoke tests. Develop plan to eliminate illicit connections: - replumb sewer lines, - isolate Problem areas, and Plug illicit discharge points. DevebP disposal options. ' Document that non -storm water discharges have been eliminated by recording tests performed, methods used. dates of testing, and any on -site drainage points observed. REFERENCES General Industrial Storm Water Permit, SWRCB,1992. NPDES General Permit for Discharges of Storm Water Associated with Industrial Activity in Santa Clara County to South San Francisco Bay or its Tributaries, SFBRWQCB, 1992. Storm Water Management for Industrial Activities: Developing Pollution Prevention Plans, and Best Manage- ment Practices, EPA 832-R-92-006, USEPA, 1992.. 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C E 1 r � � L 3 U L � 4 N 0 �y R N N a_ a t V G Q x Industrial Handbook . 4 - 10 March, 1993 ACTIVITY: VEHICLE AND EQUIPMENT FUELING DESCREMON Prevent fuel spills and leaks, and reduce their impacts to storm water. APPROACH Design the fueling area to prevent the ninon of storm water and the runoff of spills: Cover fueling area if possible. - Use a perimeter drain or slope pavement inward with drainage to sump. - Pave fueling area with concrete rather than asphalt. • Where covering' is infeasible and the fuel island is surrounded by pavement, apply a suitable sealant that protects the asphalt from spilled fuels. • If dead-end sump is not used to collect spills, install an oil/water separator. • Install vapor recovery nozzles to help control drips as well as air pollution. • Die "topping -off' of fuel tanks. • Use secondary containment when transferring fuel from the tank truck to the fuel tank. • Use adsorbent materials on small spills and general cleaning rather than hosing down the area. Remove the adsorbent materials promptly. • Catty out all Federal and State requirements regarding underground storage tanks, or install above ground tanks. • Do not use mobile fueling of mobile industrial equipment around the facility; rather, transport the equipment to designated fueling arm. • Keep your Spill Prevention Control and Countermeasure (SPCC) Plan up-to-date. • Train employees in proper fueling and cleanup procedures. • For a quick reference on disposal alternatives for spec wastes see Table 4.1, SC 1. REQUIREMENTS Costs (Capital, O&bo The retrofitting of existing fueling areas to minimize storm water exposure or spill runoff can be expensive. Good design must occur during the initial installa- tion. Extruded curb along the "upstttam" side of the fueling area to prevent storm water runon is of modest cost • Maintenance - Clean oil/water separators at the appropriate intervals. - Keep ample supplies of spill cleanup materials on -site. • Inspect fueling areas and storage tanks on a regular schedule. LIMITATIONS • Oillwater separators are only as effective as their maintenance program. Tnrinet.�..�i v.._��__• Applications Manufacturing �Mat'Handling_ Vehicle kla nt---enr�c�e� Roadways Waste Containment Targeted Constituents 0 Sediment 0 Nutrients Heavy Metals Toxic Materials 0 Flostable Materials 0 Oxygen Demand- ing Substances O11 A Grease 0 Bacteria & Viruses ukw to Ham S19WZ=ntkupact 0 Probable cow or Unknown Impact Implementation Requirements Q Capital Casts 0 O&M Costs Q Maintenance Q Training 1 0 High 0 Low i SC2 Best Management Practices - 4 - 11 March, 1993 Additional Information— Vehicle and Equipment Fueling Spills from fueling or from the transfer of fuels to the storage tank can be a significant source of pollution. Fuels carry contaminants of particular concern to humans and wildlife, such as heavy metals, toxic materials, and oil and grease, which are not easily removed by storm water treatment devices. Consequently, control at the source is particularly important. Adequate control can be achieved with careful design of the initial installation, retrofitting of existing installations, and proper spill, control and cleanup procedures, as described below. DeSion With new installations, design the fueling area to prevent the runon of storm water and the runoff of spills. This can be achieved by contouring the site in the appropriate fashion. Covering the site is the best approach but may not be feasible if very large mobile equipment is being fueled. Storm water runon can be diverted around the fueling area by an extruded curb or with a "speed bump-, if vehicle access is needed from this direction. Spills can be contained within the fueling area either by using a perimeter drain or by sloping the pavement inward with drainage to a sump. In both cases the drain can be connected to the storm drain with a valve that is only closed during fueling operations and left open at all Other times. Pave the fueling area with Portland cement concrete rather than asphalt, since the latter will gradually disintegrate and be washed from the site. Shill C'ontml The following spill control measures will reduce spilling or reduce the loss of spilled fuels from the site. - Install vapor recovery nozzles. • Do not "top off" tanks. Place secondary containment around the fuel truck when it is transferring fuel to the storage tank. The truck OMMr should remain with the truck while the transfer is in progress. • Place a stockpile of spill cleanup materials where it will be readily accessible. • Use dry methods to clean the fueling area wheneverYou Y possible. If Periodically clean by Pressure washing, place a temporary plug in the downstream drain and pump out the accumulated water. Properly dispose the water. • Train employees on proem fueling and cleanup procedures. Dmi;nate`d AA If Your facility has large numbers of mobile equipment working throughout the site and you currently fuel them with a mobile fuel truck, consider establishing a designated area for fueling. With the exception of tracked equipment such as bulldozers and perhaps small forklifts, most vehicles should be able to travel to a designated area with little lost time. Place temporary caps over nearby catch basins or manhole Covers so that if a spill occurs it is prevented from entering the storm drain. Examples of Effective Pmm ms • The Spill Prevention Control and Countermeasure (SPCC) Plan, which is required by law for some facilities, is an effective program to reduce the number of accidental spills. • The City of Palo Alto has an effective program for commercial vehicle service facilities. Many of theproggram's elements, including spec BMP guidance and lists of equipment suppliers, are also applicable to lIIs l facilities. REFERENCES Best Management Practices for Automotive -Related Industries, Santa Clara Valley Nonpoint Source Pollution Control Program,1992. Best Management Practices for Industrial Storm Water Pollution Control, Santa Clara Valley Nonpoint Source Pollution Control Program, 1992. Storm Water Management for Industrial Activities: Developing Pollution Prevention Plans, and Best Management Practices, EPA 832-R 92-006, USEPA,1992. SC2 Water Quality Best Management Practices Manual, City of Seattle, 1989. 1 Be" Industrial Handbook 4 - 12 March, 1993 • ACTIVITY: VEHICLE AND EQUIPMENT WASHING & STEAM CLEANING I Applications Manufacturing Material Handling epic% Mainierranc onstruction Commercial Activities Roadways Waste Containment DESCRIPTION Targeted Constituents Prevent or reduce the discharge of pollutants to storm water from vehicle and equipment Sediment washing and steam cleaning. � Nutrients APPROACH • Consider off -site commercial washing and steam cleaning businesses. Heavy Metals • Use designated wash areas, preferably covered to prevent contact with storm water Toxic Materials and termed to contain wash water. • Discharge wash water to sanitary sewer, after contacting local sewer authority to find O F/oatable Materials out if pretreatment is required. 9 Oxygen Demancsti Educate employees on pollution prevention measures. ing Substances • Consider filtering and recycling wash water. • Do not permit steam cleaning wash water to enter the storm drain. 9 Oil & Grease • Fora quick reference on disposal alternatives for specific wastes sea Table 4.1, SCI. O Bacteria & Viruses REQUIREMENTS tlksly to Haw • Capital costs vary depending on measures implemented. S/gnleanranpact - Low cost ($500-1,000) for berm construction. 0 Probabis Low or - Medium cost ($5,000-20,000) for plumbing modifications (including rye -routing unknown hnpact discharge to sanitary sewer and installing simple sump). Implementation High cost (S30,000-150,000) for on -site treatment and recycling. Requirements • O&M costs increase with increasing capital investment. • Maintenance Q Capital Costs - Berm repair and patching. - Inspection and maintenance of sumps, oil/water separators, and on -site treatment/ O O&M Costs recycling units. O Maintenance LIMITATIONS Q Training • Some municipalities may require pretreatment and monitoring of wash water dis- charges to the sanitary sewer. Steam cleaning can generate significant pollutant concentrations requiring permitting, monitoring, pretreatment, and inspections. The measures outlined in this fact sheet High woL are insufficient to address all the environmental impacts and compliance issues related to steam cleaning. S C3. Best Management Practices Industrial Handbook 4 - 13 March, 1993 L Additional Information Vehicle and Equipment Washing and Steam Cleaning Washing vehicles and equipment outdoors or in areas where wash water flows onto the ground can pollute storm water. If Your facility washes or steam cleans a largenumber of vehicles or pieces of equipment, consider contracting out this work to a commercial business. These businesses are better equipped to handle and dispose of the wash waters properly. Contracting out this work can also be economical by eliminating the need for a separate washing/cleaning operation at your facility. If washing/cleaning must occur on -site, consider washing vehicles inside the building to control the targeted constituents by directing them to the sanitary sewer where they can be pretreated or sent directly to the sanitary treatment facility. Washing eons outside should be conducted in a designated wash area having the following characteristics: • Paved with Portland cement concrete, • Covered or bermed to prevent contact with storm water, • Sloped for wash water collection, • Discharges wash water to the sanitary or process waste sewer, or to a dead-end sump. Discharge pipe should have a Positive control valve that allows switching between the storm drain and sanitary or process sewer, • Curly designated, and • Equipped with an oil/water separator (see Chapter 5, TC7, Oil/Water Separators and Water Quality Inlets). Examples of Effective Frog= The City of Palo Alto has an effective program for commercial vehicle service facilities. Many of the program's elements, including spec BMP guidance and lists of equipment suppliers, are applicable to industrial vehicle service facilities. The U.S_ Postal Service in West Sacramento has a new vehicle wash system that collects, filters, and recycles the wash water. REFERENCES BestManagement Practices for Automotive -Related Industries, Santa Clara Valley Nonpoint Source Pollution Control Program,1992. Best Management Practices for Industrial Storm Water Pollution Control. Santa Clara Valley Nonpoint Source Pollution Control Program,1992. Stoma Water Management for Industrial Activities: Developing Pollution Prevention Plans, and Best Management Practices, EPA 8320R-92-OK USEPA, 1992. Water Quality Best Management Practices Manual, City of Seattle, 1989. I SC3 I Industrial Handbook 4 - 14 March, 1993 ACTIVITY; VEHICLE AND EDUIPMENT MAINTENANCE AND REPAIR DIKE TO PREVE SPILLS .EAKS FROM ENTERIN STORM DRAIN DESCRIPTION Prevent or reduce the discharge of pollutants to storm water from vehicle and equipment maintenance and repair by running a dry shop. APPROACH • Keep equipment clean, don't allow excessive build-up of oil and grease. • Keep drip pans or containers under the areas that might drip. • Do not change motor oil or perform equipment maintenance in non -appropriate areas. Use a vehicle maintenance area designed to prevent storm water pollution. Inspect equipment for leaks on a regular basis. • Segregate wastes. • Make surge oil meters are completely drained and crushed before recycling or disposal.. • Make sure incoming vehicles are checked for leaking oil and fluids. • Clean yard storm drain mlets(s)segularly and especially after large storms. • Do not pour materials down drains or hose down work areas; use dry sweeping. • Stone idle equipment under cover. • Drain all fluids from wrecked vehicles. • Recycle greases, used oil or oil filters, antfreeze, cleaning solutions. automotive batteries, hydraulic, and transmission fluids. • Switch to non -toxic chemicals for maintenance when possible. • Clean small spills with rags, general clean-up with damp mops and larger spills with absorbent material. • Paint signs on storm drain inlets to indicate that they are not to receive liquid or solid wastes. • Train employees. , • Minimize use of solvents. • For a quick reference on disposal alternatives for specific wastes see Table 4.1, SCI_ REQUIREMENTS • Costs (Capital, O&M) Should be low, but will vary depending on the size of the facility. • Maintenance - Should be low if procedures for the approach are followed. LIMITATIONS • Space and time limitations may preclude all work being conducted indoors. • It may not be possible to contain and clean up spills from vehicles/equipment brought on -site after working hours. • DMia pans .(usually I ft. x 1 ft.) are generally toosmall to contain antifreeze, which may gush from some vehicles, so dria pans (3 ft. x 3 Q may have to be purchased or fabricated. • Dry floor cleaning methods may not be sufficient for some spills. Use three -step method instead. • Identification of engine leaks may require some use of solvents. Applications Manufacturing Aosdways Waste Containment Targeted Constituents 0 Sediment 0 Nutrients Heavy Metals a Toxic Materials O Flostable Materials 0 Oxygen Demarnd� ing Substances Oil & Gresse 0 Bacteria & Viruses Si to Pact O Probable Lowor Unknown Impact Implementation Requirements O Capital Costs Q O&M Costs Q Maintenance Q Training I High 0 tow +1 SC4 Best' Mana Industrial Handbook 4 - 15 March, 1993 Additional Information— Vehicle and Equipment Maintenance and Repair Vehicle or equipment maintenance is a potentially significant source of storm water pollution. Activities that can contaminate storm water include engine repair and service (parts cleaning, spilled fuel, oil, etc.), replacement of fluids, and outdoor. equipment storage and parking (dripping engines). For further information on vehicle or equipment servicing, see SC2, Vehicle and Equipment Fueling, and SC3, Vehicle and Equipment Washing and Steam Cleaning. Waste Reduction Parts are often cleaned using solvents such as tricbloroethylene, 1,1,1-trichloroethane or methylene chloride. Many of these cleaners are harmful and must be disposed of as a hazardous waste. Cleaning without using liquid cleaners (e.g. wire brush) whenever possible reduces waste, prevent spills and drips of solvents and cleansers to the shop floor. Do all liquid cleaning at a centralized station so the solvents and residues stay in one area. Locate drip pans, drain boards, and drying tacks to direct drips back into a solvent sink or fluid holding tank for re -use. Safer Altemnti -e If possible. eliminate or reduce the amount of hazardous materials and waste by substituting non -hazardous or less hazardous materials. For example: • Use non -caustic detergents instead of caustic cleaning agents for parts cleaning (ask your supplier about alternative cleaning agents). • Use detergent -based or water4med cleaning systems in place of organic solvent degreasers. Wash water may require treatment before it can be discharged to the sewer. Contact your local sewer authority for more information. • Replace chlorinated organic solvents (1,1.1-trichloroethane, methylene chloride, etc.) with non -chlorinated solvents. Non -chlorinated solvents like kerosene or mineral spirits are less toxic and less expensive to dispose of properly. Check list of active ingredients to see whether it contains chlorinated solvents. The "chlor" term indicates that the solvent is chlorinated. • . Choose cleaning agents that can be recycled. Contact your supplier or refer to trade journals for more waste minimization ideas. Reducing the number of solvents makes recycling easier and reduces hazardous waste management costs. Often, one solvent can perform a job as well as two different solvents. E=Iin. Separating wastes allows for easier recycling and may reduce. treatment costs. Keep hazardous and non -hazardous wastes separate, do not mix used oil and solvents. and keep chlorinated solvents (like 1,1,1-trichlocoethane) separate from non -chlorinated solvents (like kerosene and mineral spirits). Many Products made of recycled (Le., refined or purified) materials are available. Engine oil. transmission fluid, antifreeze. and hydraulic fluid are available in recycled form. Baying recycled products supports the market for recycled materials.11 Snip I . ak Clean 112 Clean leaks, drips, and other spills with as little water as possible. Use rags for small spills, a damp mop for general cleanup, and dry absorbent material for larger spills. Use the following three -step method for cleaning floors: 1. Clean spills with rags or other absorbent materials. 2. Sweep floor using dry absorbent materiaL 3. Mop floor' Mop water may be discharged to the sanitary sewer via a toilet or sink. 1 SC4 1 Industrial Handbook 4 - 16 March, 1993 0 Additional Information— Vehicle and Equipment Maintenance and Repair Good Ho sekeening Also consider the following measures: • Avoid hosing down your work areas. If work areas are washed, direct wash water to sanitary sewer. Collect leaking or dripping fluids in drip pans or containers. Fluids are easier to recycle if kept separate. • Keep a drip pan under the vehicle while you unclip hoses, unscrew filters, or remove other parts. Use a drip pan under any vehicle that might leak while you work on it to keep splatters or drips off the shop floor. • Promptly transfer used fluids to the proper waste or recycling drums. Don't leave full drip pans or other open containers lying around. Do not pour liquid waste to floor drains, sinks, outdoor storm drain inlets. or other storm drains or sewer connections. Used or leftover cleaning solutions, solvents, and automotive fluids and oil are toxic and should not be put in the sanitary sewer. Post signs at sinks to remind employees, and paint stencils at outdoor drains to tell customer and others not to pour wastes down drains. Oil filters disposed of in trash cans or dumpsters can leak oil and contaminate storm water. Most municipalities prohibit or discourage disposal of these items in solid waste facilities. Place the oil filter in a funnel over the waste oil recycling or disposal collection tank to drain excess oil before disposal. Oil filters can be crushed and recycled Ask your oil supplier or recycle about recycling oil filters. Put pans under leaks to collect fluids for proper recycling or disposal. Keeping leaks off the ground reduces the potential for storm water contamination and reduces cleanup time and costs. If the vehicle or equipment is to be stored outdoors, oil and other fluids should be drained first. Designate a special area to drain and replace motor oil, coolant, and other fluids, where there are no connections to the storm drain or the sanitary sewer and drips and spills can be easily cleaned up. Be especially careful with wrecked vehicleswhether you keep them indoors or out, as well as vehicles kept on -site for scrap or salvage. Wrecked or damaged vehicles often drip oil and other fluids for several days. • As the vehicles arrive, plate drip pans under them immediately, even if you believe that the fluids have leaked out before the car reaches your shop. • Build a shed or temporary roof over areas where you park cars awaiting repair or salvage, especially if you handle wrecked vehicles. Build a roof over vehicles you keep for parts. • Drain all fluids, including air conditioner coolant, from wrecked vehicles and "part" cars. Also drain engines, transmission, and other used parts. • Store cracked batteries in a non -leaking secondary container. Do this with all cracked batteries, even if you think all the acid has drained out. If you drop a battery, treat it as if it is cracked. Put it into the containment area until you are sure it is not leaking. Examples of Effective Programs The City of Palo Alto has an effective program for commercial vehicle service facilities. Many of the program's elements, including specific BMP guidance and lists of equipment suppliers. are also applicable to l vehicle service facilities. Pick N Pull Auto Dismantlers in Rancho Cordova drains all fluids from automobiles before they enter the yard. Ecology Auto Wrecking in Rialto is surrounded by a steel plate/concrete fence and has a completely paved lot that is graded to a central low point. Collected storm water is channeled through as underground drainage system of clarifiers 1 SC4 1 Industrial Handbook 4.- 17 March, 1"3 Additional Information— Vehicle and Equipment Maintenance and Repair and then stoned in a 60,000 gallon UST before being processed through a filter system. In addition, the work area is covered, ventilated and has an additional sump. Vehicle fluids are drained in this area and segregated for recycling. All Auto Parts, Fontana, has a complete water recycling system in a 10,000 square foot concrete slab surrounded by a curb that contains all the runoff and sends it to the recycling system. All receiving, dismantling, and shipping occurs on the slab. REFERENCES Best Management Practices for Automotive -Related Industries, Santa Clara Valley Nonpoint Source Pollution Control Program.1992. Best Management Practices for Controlling Oil and Grease in Urban Stone Water Runoff, G. S. Silverman, et. al, 1986 Environmental Professional, Vol. 8, pp 351-362 Best Management Practices for Industrial Storm Water Pollution Control. Santa Clara Valley Nonpowt Source Pollution Control Program,1992 Fact Sheet - WasteReduction for Automotive Repair Shops; DISC, 1989. Hazardous Waste Reduction Assessment Handbook - Automotive Repair Shops; DTSC,1988. Hazardous Waste Reduction Checklist - Automotive Repair Shops; DTSC,1988. Storm Water Management for industrial Activities: Developing Pollution Prevention Plans, and Best Management Practices, EPA 832-R 92-006, USEPA, 1992 SC4 Industrial Handbook 4 - 18 March, 1993 ACTIVITY: oUTDOOR LOADINGIUNLOADING OF MATERIALS DESCRUMON Prevent or reduce the discharge of pollutants to stoma water from outdoor loading/ unloading of materials, APPROACH Park lank trucks or delivery vehicles so that spills or leaks can be contained. • Cover the loadinglunloading docks to reduce exposure of materials to rain. • Seal or door skirt between trailer and building can also prevent exposure to rain. • Design loading/unloading area to prevent storm water runon: - gang or berming, and Position roof downspouts to direct storm water away from loading/unloading areas. • Contain leaks during transfer. • Use drip pans under hoses. • Make sure fork lift operators are properly trained. • Employee training for spill containment and cleanup. REQUIREMENTS • Costs (Capital, O&M) - Should be low except when covering a large loading/unload- ing area. • Maintenance Conduct regular inspections and make repairs as necessary. The frequency of repairs will depend on the age of the facility. Check loading and unloading equipment regularly for leaks: - valves, - PUMPS. - flanges, and - connections. LIMITATIONS • Space and time limitations may preclude all transfers from being performed indoors or under cover. It may not be possible to conduct transfers only during dry weather. Industrial Handbook 4 19 Applications Manufacturing Material Handling Vehicle Maintenance onstruction Commercial Activities Roadways Waste Containment Targeted Constituents 0 Sediment Nutrients Heavy Metals Toxic Materials Floatab/e Materials Oxygen Demand. ing Substances Oil & Grease 0 Bacteria & Viruses • Ukely to Have Siyruficannt bnpact 0 Probable tow or Unknown impact Implementation Requirements Q Capital Costs 0 O&M Costs 0 Maintenance Q Training High 0 Low SC, Best Managemen Practices March, 1993 • 0 Additional Information— Outdoor LoadingNnloading of Materials The loading/unloading of materials usually takes place outside. Loading or unloading of materials occurs in two ways: materials in containers or direct liquid transfer. Materials spilled, leaked or lost during loading/unloading may collect in the soil or on other surfaces and be carried away by runoff or when the area is cleaned Rainfall may wash pollutants from machinery used to unload or move materials. The loading or unloading may involve rail or truck transfer. The most important factors in preventing these constituents from entering storm water is: • Limit exposure of material to rainfall • Prevent storm water runon. • Check equipment regularly for leaks. • Contain spills during transfer operations. Loading or unloading of liquids should occur in the manufacturing building so that any spills that are not completely retained can be discharged to the sanitary sewer, treatment plant, or treated in a manner consistent with local sewer authorities and permit requirements. Best management practices include: Use overhangs or door skirts that enclose the trailer. • Park tank trucks during delivery so that spills or leaks can be contained. • Design loading/unloading area to prevent storm water runon which would include grading or terming the area, and Positioning roof downspouts so they direct storm water away from the loading/unloading areas. • Check loading and unloading equipment regularly for leaks, including valves, pumps, flanges and connections. • Look for dust or fumes during loading or unloading operations. • Use a written operations plan that describes procedures for loading and/or unloading.. • Have an emergency spill cleanup plan readily available. • Employees trained in spill containment and cleanup should be present during the loading/unloading. • Establish depots of cleanup materials next to or near each loading/unloading area, and train employees,in their use. • For loading and unloading tank trucks to above and below ground storage tanks, the following procedures should be used - The area where the transfer takes place should be paved. If the liquid is reactive with the asphalt, Portland cement should be used to pave the area. - Transfer area should be designed to prevent runon of storm water from adjacent areas. Sloping the pad and Ong a curb. like a speed bump, around the uphill side of the transfer area should reduce runon. Transfer area should be designed to prevent runoff of spilled liquids from the area. Sloping the area to a drain shouts prevent runoff. The drain should be connected to a dead-end sump or to the sanitary sewer. A positive control valve should be installed on the drain. • For transfer from rail cars to storage tanks that must occur outside, use the following procedures: Drip pans should be placed at locations where spillage may occur, such as hose connections, hose reels, and filler nozzles. Use drip pans when making and breaking connections. - Drip pan systems should be installed between the rails to collect spillage from tank cars. REFERENCES Best Management Practices for Industrial Storm Water Pollution Control, Santa Clara Valley Nonpoint Source Pollution Control Program, 1992 Storm Water Management for Industrial Activities: Developing Pollution Prevention Plans, and Best Management Practices, EPA 832-R-92-006, USEPA. 1992. Water Quality Best Management Practices Manual, City of Seattle, 1989. SC5 v, Industrial Handbook 4 - 20 March, 1993 ---------------- ACTIVITY: OUTDOOR CONTAINER STORAGE OF LIQUIDS Applications Manufacturing COVER TO MINIMIZE Material Handling STORM WATER Vehicle Maintenance 1•t'i"p-it Construction 1J! Comme�ial Activhies Roadways OSPDIKE TO I I.LSISTORMAWATER IN Waste Containment i a"n Prevent or reduce the discharge of pollutants to storm water from outdoor container storage Targeted Constituents areas by installing safeguards against accidental releases, installing secondary containment, 0 Sediment conducting regular inspections, and training employees in standard operating procedures O Nutrients and spill cleanup techniques. � Heavy Metals APPROACH • Protect materials from rainfall, runon, runoff. and wind dispersal: Toxic Materials - Store materials indoors. O Floatable Materials - .Cover the storage area with a roof. - Minize storm water runon by enclosing the area or buiding a berm around it Oxygen Demand- - Use "doghouse" for storage of liquid containers. ing Substances - Use covered dumpsters for waste product containers. Q Oil A Grease • Storage of oil and hazardous materials must meet specific Federal and State standards including. Q Bacteria & Viruses - Spill Prevention Control and Countermeasure Plan (SPCC) Plan, - secondary containment, L"w- to Ham t /mpact - integrity and leak detection, monitoring, and ProbableLow emergency P�� Pam. O � • Train operator on proper storage. Implementation • Safeguards against accidental releases: - overflow protection devices to warn operator or automatic shut down transfer Requirements PUMPS, - protection guards (bollards) around tanks and piping to prevent vehicle or forklift 0 Capital Costs damage, and clear tagging or labeling. and restricting access to valves to reduce human error. Q OAM Costs • Berm Or surround tank or container with secondary containment system: 0 Maintenance - dikes. liners, vaults, or double walled tanks. • Some municipalities require that secondary containment areas be connected to O Training the sanitary sewer, prohibiting any hard connections to the scorn drain. • Facilities with "spill ponds" designed to intercept, treat, and/or divert spills should Ict the appropriate regulatory agency regarding envirinmental compliance. g Q Low Q SC6• Cost (Capital, O& ) Will vary depending on the size of the facility and the necessary controls. • Maintenance: Conduct routine weekly inspections. LIMITATIONS Best • Storage sheds often must meet building and fire code requirements. Managem Practices) Industrial Handbook 4 - 21 March, 1993 Additional Information— Outdoor Container Storage of Liquids Accidental releases of materials from aboveground liquid storage tanks, drums, and dumpsters sent the poten- tial for contaminating storm waters with many different pollutants. Materials spilled. leaked or lost from storage containers and dumpsters may accumulate in soils or on the surfaces and be carried away by storm water runoff. These source controls apply to containers located outside of a building used to temporarily d materials. It should be noted that the storage of reactive, ignitable, or flammable liquids must comply � fire codes. Container M navemen To limit the possibility of storm water pollution, containers used to store dangerous waste or other liquids should be kept inside the building unless this is impractical due to site constraints. If the containers are placed outside, the following procedures should be employed: • Dumpsters used to store items awaiting transfer to a landfill should be placed in a lean-to structure or other- wise covered. dumpsters shall be kept in good condition without corrosion or leaky seams. Garbage dumpsters shall be replaced if they are deteriorating to the point where leakage is occurring. It Should be kept undercover to prevent the entry of storm water. Employees should be made aware of the importance of keeping the dumpsters covered and fire from leaks, ' A fillet should be placed on both sides of the curb to facilitate moving the dumpster. • Waste container drums should be kept in an area such as a service bay. If drums are kept outside, they must be stored in a lean-to type structure, shed or walk-in container to keep rainfall from reaching the drums. Storage of reactive, ignitible, or flammable liquids must comply with the fire codes of your area. Practices listed below should be employed to enhance the fire code requirements, • Containers should be placed in a designated area, • Designated areas should be paved, free of cracks and gaps, and impervious in order to contain leaks and spills. • Liquid waste should be surrounded by a curb or dike to provide the volume to contain 10 percent of the volume of all of the containers or 110 percent of the volume of the largest container, whichever is greater. • The area inside the curb should slope to a drain. - For used oil or dangerous waste, a dead-end sump should be installed in the drain. - All other liquids should be drained to the sanitary sewer if available. The drain must have a positive control such as a lock, valve, or plug to prevent release of contaminated liquids. • The designated storage area should be covered • Containers used for liquid removal by an employees must be placed in a containment area. A drip pan should be used at all times. • Drums stored in an area where unauthorized persons may gain access must be secured to prevent accidental spillage, Pilferage, or any unauthorized use. • Employees trained in emergency spill cleanup procedures should be present when dangerous waste, liquid chemicals, or other wastes are loaded or unloaded. The most common causes of unintentional releases: External corrosion and structural failure, • Installation problems, • Spills and overfills due to operator error, • Failure of piping systems (Pipes, pumps, flanges, couplings, hoses, and valves), and Leaks during pumping of liquids or gases from truck or railcar to a storage facility or vice versa. QiOr Trai .n:aaf -u rds Well -trained employees can reduce human errors that lead to accidental releases or spills. Employees should be familiar with the Spill Prevention Control and Countermeasure Plan. The employee should have the tools and knowledge to SC6 Industrial Handbook 4 22 March, 1993 • 0 Additional Information Outdoor Container Storage of Liquids immediately begin cleaning up a spill if one should occur. Operator errors can be prevented by using engineering safe guards and thus reducing accidental releases of pollutant. Safeguards include: • Overflow protection devices on tank systems to warn the operator to automatically shutdown transfer pumps when the tank teaches full capacity, • Protective guards (bollards) around tanks and piping to prevent vehicle or forklift damage. and Clearly tagging or labeling all valves to reduce human error. Tank systems should be inspected and tank integrity tested regularly. Problem areas can often be detected by visually inspecting the tanks frequently. Problems or potential problems should be corrected as soon as possible. Registered and specifically trained professional engineers can identify and correct potential problems such as loose fittings, poor welding, and improper or poorly fitted gaskets for newly installed tank systems. The tank foundations, connections, coatings, and tank walls and piping systems also should be inspected. Inspection for corrosion, leaks, cracks, scratches in protective coatings, or other physical damage that may weaken the tank system should be a part of regular integrity testing. cmndfwv Tanks should be bermed or surrounded by a secondary containment system. Leaks can be detected more easily and spills can be contained when a secondary containment systems are installed Berms, dikes, liners, vaults, and double -wall tanks are examples of secondary containment systems. One of the best protective measures against contamination of stone water is diking. Containment dikes are berms or retaining wails that are designed to hold spills. Diking is an effective pollution prevention measure for above ground storage tanks and railcar or tank truck loading and unloading areas. The dike surrounds the area of concern and holds tt spill, keeping spill materials separated from the storm water side of the dike area. Diking can be used in any industrial facility, but it is most commonly used for controlling large spills or releases from liquid storage areas and liquid transfer areas. For single-waA tanks, containment dikes should be large enough to hold the contents of the storage tank for the facility plus ram water For trucks, diked areas should be capable of holding an amount equal to the volume of the tank truck compartment Diked construction material should be strong enough to safely hold spilled materials. Dike materials can consist of earth, concrete, synthetic materials, metal, or other impervious materials. Strong acids or bases may react with metal containers, concrete, and some plastics. Where strong acids or bases or stored, alternative dike materials should be considered More active organic chemicals may need certain special liners for dikes. Dikes may also be designed with impermeable materials to increase containment capabilities. Dikes should be inspected during or after significant storms or spills to check for washouts or overflows. Regular checks of containment dikes to insure the dikes are capable of holding spills should be conducted. Inability of astructure to retain storm water, dike erosion, soggy areas, or changes in vegetation indicate problems with dike structures. Damaged areas should be patched and stabilized immediately. Earthen dikes may require special maintenance of vegetation such as mulching and irrigation. Curbing is a barrier that surrounds an area of concern. Curbing is similar to containment diking in the way that it preveiu: Spills and leaks from being released into the environment. The curbing is usually small scaled and does not Contain large Spills like diking. Curbing is Common at many facilities in small areas where handling and transfer liquid materials occur. Curbing can redirect contaminated storm water away from the storage area. It is useful in areas where liquid materials are transferred from one container to another. Asphalt is a common material used for curbing; however, curbing materials include earth, concrete, synthetic materials, metal, or other impenetrable materials. Spilled materials should be removed immediately from curbed areas to allow space for future spills. Curbs should have manually -controlled pump systems rather than common drainage systems for collection of spilled materials. The curbed area should be inspected regularly to clear clogging debris. Maintenance should also be conducted frequently to prevent overflow of any spilled materials as curbed areas are designed only for smaller spills. Curbing has the following advantages: • . Excellent runon control, SCS • Inexpensive, • Ease of installment, • Provides option to recycle materials spilled in curb areas, and Common industry practice. Industrial Handbook 4 - 23 March, 1993 i Additional Information— Outdoor Container Storage of Liquids • Weekly inspection should be considered and include. - Check for external corrosion and structural failure, - Check for spills and overfills due to operator error, - Check for failure of piping system (pipes. pumps, flanges, coupling, hoses, and valves), - Check for leaks or spills during pumping of liquids or gases from truck or rail car to a storage facility or vice versa, - Visually inspect new tank or container installation loose fittings, poor welding, and improper or poorly fitted gaskets, and - Inspect tank foundations, connections, coatings, and tank walls and piping system. Look for corrosion, leaks, cracks, scratches, and other physical damage that may weaken the tank or container system. The "doghouse" design has been used to store small liquid containers. The roof and flooring design prevent contact with direct rain runoff. The doghouse has two solid structural walls and two canvas covered walls. The flooring is wire mesh about secondary containment. The unit has been used successfully at Lock -heed Missile and Spate Company in Sunnyvale. REFERENCES Best Management Practices for Industrial Storm Water Pollution Control, Santa Clara Valley Nonpoint Source Pollution Control Program, 1992 Storm Water Management for Industrial Activities; Developing Pollution Prevention Plans, and Best Management Practices, EPA 832-R-92-006, USEPA, 1992 Water Quality Best Management Practices Manual, City of Seattle, 1989. Industrial Handbook 4 - 24 March, 1993 ACTIVITY: OUTDOOR PROCESS EQUIPMENT OPERATIONS AND MAINTENANCE 4#qL- .,y' STORM WATER Applications Manufacturing Material Handling, Vehicle Maintenance Construction ommemiel Activities Roadways Waste Containment DESCRIPTION Targeted Constituents Prevent or reduce the discharge of pollutants to storm water from outdoor process equip- 0 Sediment went operations and maintenance by reducing the amount of waste created, enclosing or covering all or some of the equipment, installing secondary containment, and training Nutrients employees. Heavy Metals APPROACH 0 Toxic Materials • Alter the activity to prevent exposure of pollutants to storm water. • Move activity indoors. 0 Floatable Materials • Cover the area with a permanent roof. - Oxygen Demand 0 • Minimize contact of storm water with outside manufacturing operations through ing Substances terming and drainage routing (run on prevention). • Connect process equipment area to pubic sewer or facility wastewater treatment 9 Oil & Grease system. • Clean regularly the storm drainage system. 0 Bacteria & wruses • Use catch basin filtration inserts (Chapter 5, TC6, Media Filtration) as a means to capture particulate pollutants. 0 Ukely to Haw Signi4cant hnpact ` Some municipalities require that secondary containment areas (regardless of size) be Q Probable Low or unimon" Impact connected to the sanitary sewer, prohibiting any hard connections to the storm drain. REQUUUME TS Implementation • Costs (Capital, O&M) Requirements Variable depending on the complexity of the operation and the amount of control Capital Costs necessary for storm water pollution control.. • Maintenance 0 O&M Costs - Routine preventive maintenance, including checking process equipment for leaks. 0 maintenance 0 Training LIMITATIONS • Providing cover may be expensive. • Space limitations may preclude enclosing some equipment. • Storage sheds often must meet building and fire code requirements. High 0 Low SC7 Best Managemen Practices Industrial Handbook 4 - 25 March, 1993 0 n Additional Information— Outdoor Process Equipment Operations and Maintenance 11 Outside process equipment operations can contaminate storm water runoff.. Activities, such as rock grinding or crush- ing, painting or coating, grinding or sanding, degreasing or parts cleaning, landfills, waste piles, wastewater and solid waste treatment and disposal, and land application are process operations that use hazardous materials and that can lead to contamination of storm water runoff. Pollutants from the wastewater and solid waste treatment and disposal areas result from waste pumping, additions of treatment chemicals, mixing, aeration, clarification, and solids dewatering. Possible storm water contaminants include heavy metals, toxic materials. and oil and grease. Waste spilled, leaked, or lost from outdoor process equipment operations may build up in soils or on other surfaces and be carried away by storm water runoff. There is also a potential for liquid waste from lagoons or surface impoundments, associated with outdoor equipment operations, to overflow to surface waters or soak the soil, which can be picked up by stout water runoff. The preferred (and possibly the most economical) action to reduce storm water pollution is to alter the nature of activity such that pollutants are not exposed to storm water. This may mean perfoming the activity during dry periods only or substituting benign materials for more toxic ones. Actions other than altering the activity include enclosing the activity in a building and connecting the floor drains to the sanitary sewer. The area used by the activitymay be so great -as to make enclosure prohibitively expensive. Building cost can be reduced by not covering the sides, and thus eliminating the need for ventilating and lighting systems. When certain parts of the activity are the worst source of pollutants, those Parts can be segregated and enclosed or covered. Curbs can be placed around the immediate boundaries of the process equipment. The storm drains from these interior areas can be connected to the facility's process wastewater system. Reducing the amount of waste that is created and consequently the amount that must be stored of treated is another way to reduce the potential for storm water contamination from outside manufacturing activities. Waste reduction BMPs are available for a wide range of industries and are designed to provide ideas and ways to reduce waste (see References). Hydraulic)Treatment Modifications If storm water becomes polluted, it should be captured and treated. If you do not have your own process wastewater treatment system, consider discharging to.the public sewer system. Use of the public sewer might be allowed under the following conditions: If the activity area is very small (less than a few hundred square feet), the local sewer authority may be willing to allow the area to remain uncovered with the drain connected to the public sewer. • It may be possible under unusual circumstances to connect a much larger area to the public sewer, as long as the rate Of storm water discharges do not exceed the capacity of the wastewater treatment plant. The storm water could be stoned during the storm and then transferred to the public sewer when the normal flow is Iow, such as at night. The majority of the pollutants in storm water are discharged over time by the small. high frequency storms. Less polluted runoff from the infrequent large storms can be bypassed to the storm drain. To implement this BMP, a hydrau- lic evaluation of the downstream sewer system should occur in consultation with the local sewer authority. Industries that generate large volumes of process wastewater typically have their own treatment system that discharges directly to the nearest receiving water. These industries have the discretion to use their wastewater treatment system to treat storm water within the constraints of their permit requirements for process treatment. It may also be possible for the industry to discharge the storm water directly to its effluent outfall without treatment as long as the total loading of the discharged process water and storm water does not exceed the loading bad a storm water treatment device been used. This could be achieved by reducing the loading from the process wastewater treatment system. Check with your Re- gional Water Quality Control Board, as this option would be subject to permit constraints and potentially regular monitoring. $C7 Industrial Handbook 4 - 26 March, 1993 March, 1"3 0 • i # ACTIVITY: OUTDOOR STORAGE OF RAW MATERIALS, PRODUCTS, AND BY PRODUCTS DESCRIPTION Prevent or reduce the discharge of pollutants to storm water from outdoor material and Product storage areas by enclosing or covering materials, installing secondary contain- ment, and preventing storm water nmon. APPROACH • Protect materials from rainfall, runon, runoff and wind dispersal: - Store material indoors, - Cover the storage area with a roof. - Cover the material with a temporary covering made of polyethylene, polypro- pylene, or hypalon. Mmumize storm water runon by enclosing the area or building a berm around the area. Use "doghouse" for storage of liquid containers. • Parking lots or other surfaces near bulk materials storage areas should be swept Periodically to remove debris blown or washed from storage area. • Install pellet taps at storm water discharge points where plastic pellets are loaded and unloaded. • Keep liquids in a desig containment. nated area on a paved impervious surface within a secondary • Keep outdoor storage containers in good condition. • Use berms and curbing. • Use catch basin filtration inserts (Chapter 5, TC6, Media Filtration) REQUIREMENTS • Costs (Capital, O&M) Costs should be low except where large areas may have to be covered. • Maintenance - Berm and curbing repair and patching. LIMITATIONS • Space limitations may preclude storing some materials indoors. • Some municipalities require that secondary containment areas (regardless of size) be connected to the sanitary sewer, prohibiting any hard connections to the storm drain. • Storage sheds often must meet building and fire code requirements. Industrial Handbook 4-28 Applications Manufacturing Material Handling. Vehicle Maintenance Construction Commercial Activities Roadways Waste Containment Targeted Constituents Sediment 0 Nutrients Heavy Metals Toxic Materials Ficatable Materials 0 Oxygen Demand. ing substances Oil & Grease 0 Bacteria & Viruses Ukely to Have Significant /mpact 0 Probable Low or Unknown impact Implementation Requirements Q Capital Costs 0 O&M Costs 0 Maintenance Q Training High 0 Low SC8 Best Management Practices March,.1993 IAdditional Information Outdoor Storage of Raw Materials, Products, and By -Products I Raw materials, by-products, finished products, containers, and material storage areas exposed to rain and/or runoff can pollute storm water. Stone water can become contaminated by a wide range of contaminants when materials wash off or dissolve into water or are added to runoff by spills and leaks. Paved areas should be sloped in a manner that minimize the pooling of water on the site. particularly with materials that tray leach pollutants into storm water and/or groundwater, such as compost, logs; and wood chips. A minimum slope of 1.5 percent is recommended. Curbing should be placed along the perimeter of the area to prevent the runon of uncontaminated storm water from adjacent areas as well as runoff of storm water from the stockpile areas. The storm drainage system should be designed to minimize the use of catch basins in the interior of the area as they tend to rapidly fill with manu- facturing mate. In these cases, consider the use of the catch basin insert filter described in Chapter 5, TC6 (Media Filtration). The area should be sloped to drain storm water to the perimeter where it can be collected or to internal drainage alleyways where material is not stockpiled. If the raw material, by-product, or product is a liquid, more information for outside storage of liquids can be found under SC6, Outdoor Container Storage of Liquids. Examples The 'doghouse" design has been used to store small liquid containers. The roof and flooring design prevent contact with direct rain or runoff. The doghouse has two solid structural walls and two canvas covered walls. The flooring is wire mesh about secondary containment. The unit has been used successively at Lockheed Missile and Space Company in Sunnyvale. REFERENCES Best Management Practices for Industrial Storm Water Pollution Control, Santa Clara Valley Nonpoint Source Pollution Control Program,, 1992. Stone Water Management for Industrial Activities: Developing Pollution Prevention Plans, and Best Management Practices, EPA 832-R-92-006, EPA,1992. Water Quality Best Management Practices Manual, City of Seattle, 1989. I SC8 1 Industrial Handbook 4 - 29 March, 1993 - II ACTIVITY; WASTE HANDLING AND DISPOSAL RECYCLABLE WASTE ONLY Applications Manufacturing Material Handling Vehicle Maintenance onstruction Commercial Activities Roadways Waste Containment DESCRIPTION Prevent or reduce the discharge of pollutants to storm water from waste handling and Targeted Constituents disposal by tracking waste generation, storage, and disposal; reducing waste generation and disposal through source reduction, re -use, 0 Sediment and recycling; and preventing runon and runoff from waste management areas. . 0 !Nutrients APPROACH Heavy Metals • Maintain usage inventory to limit waste generation. Toxic Materials- 0 Raw material substitution or elimination. 0 Floatab/e Materials • Proem or equipment modification. • Production planning and sequencing.' 0 Oxygen Demand SARA Title III, Section 313 re • quires reporting for over 3(X? listed chemicals and ing Substances chemical compounds. This requirement should be used to track these chemicals although this is not 9 Oil & Grease as accurate a means of tracking as other approaches. • Track waste generated. Bacteria & Viruses - Characterize waste Stream - Evaluate 0 ukek to Have the process generating the waste. S1Vdfi=nt hnpact - Prioritize waste streams using: manifests, biennial tal audits, SARA Title III �°� ��� environmen- r eports, 0 Probable Low or unknown Impact emission reports, NPDES monitoring reports. - Inventory reports. - Data on chemical spills. Implementation - Emissions. Requirements - Shelf life expiration. • Use design data and review: process flow diagram, 0 Capital Costs materials and applications diagram, piping and instructions, equipment list, plot plan. O O&M Costs • Use raw material and production data and review: composition sheets, materials safety data sheets (MSDS), batch sheets, product or 0 Maintenance raw material inventory records, produc- tion schedule, operator data log. O Training • Use economic data and review: - Waste treatment and disposal cost. - Product utility and economic cost. - Operation and 1 High0 Low maintenance labor cost • Recycle materials whenever possible. • Maintain list of and the amounts of materials disposed S C 9 • Waste segregation and separation. . • Check industrial waste management areas for spills and leaks. • Cover, enclose, or berm industrial wastewater management areas whenever possible to . . . . . . . . . . . . prevent contact with runon or runoff. Best • Equip waste transport vehicles with and -spill equipment. Managemen Practices Industrial Handbook. 4 " 30 .March, 1993 ACTIVITY: WASTE HANDLING AND DISPOSAL (Continue) �) • Minimize spills and fugitive losses such as dust or mist from loading systems. • Ensure that sediments or wastes are prevented from being tracked off -site. • Training and supervision. • Stencil storm drains on the facility's property with prohibitive message regarding waste disposal. • For a quick reference on disposal alternatives for specific wastes see Table 4.1. SC 1. • Consider ordering industry -specific or waste stream -specific guidance from PPIC (see Appendix G). REQUEREMENTS • Costs (Capital, O&M) Capital and O&M costs for these programs will vary substantially depending on the size of the facility and the types of waste handled. Costs should be low if there is an inventory program in place. • Maintenance None except for maintaining equipment for material tracking program. LEUrATIONS • Hazardous waste that cannot be re -used or recycled must be disposed of by a licensed hazardous waste hauler. Industrial Handbook 4 - 31 March, 1993 Additional Information — Waste Handling and Disposal Industrial waste management activities occur in areas that can contaminate storm water and include landfills, waste piles, wastewater and solid waste treatment and disposal, and land application. Typical operations which affect storm water ing. pollution may include waste pumping, treatment chemicals storage, mixing, aeration, clarification, and solids dewater- Waste Reduction Waste spilled, leaked, or lost fromwaste management areas or outside manufacturing activities may build up in soils or in other surfaces and be carried away by storm water runoff. There is also a potential for liquid waste from lagoons or surface impoundments to overflow to surface waters or soak the soil where pollutants may be picked up by storm water runoff. Waste reduction for manufacturing activities is the best way to reduce the potential of storm water contamination from I" management areas. Reduction in the amount of industrial waste generated can be accomplished using many different types of source controls such as: • Production planning and sequencing. • Process or equipment modification. • Raw material substitution or elimination. Lass prevention and housekeeping. . • Waste segregation and separation. • Close loop recycling. An approach to reduce storm water pollution from waste handling and disposal is to assess process activities at the facility and reduce waste genera[ion. The assessment is designed to find situations where waste can be eliminated or reduced and emissions and environmental damage can be minimized, The assessment involves collecting process specific information, setting pollution prevention targets, and developing, screening and selecting waste reduction Options for further study. Starting a waste reduction program is economically beneficial because of reduced raw material purchases and lower waste disposal fees. to addition, material tracking systems to increase awareness about material usage can reduce spills and minimize contamination, thus reducing the amount of waste produced. Snill/l.eak Control Waste can be prevented from contaminating storm water by checking waste management areas for leaking containers or spills. Corroded or damaged containers can begin to leak at any time. Transfer waste from these damaged into safe containers. Dumpsters should be covered to prevent rain from washing waste out of holes or cracks in the bottom of the dumpster. Leaking equipment including valves, lines, seals, or pumps should be repaired promptly. Vehicles transporting waste should have spill prevention equipment that can prevent spills durin prevention equipment includes: g transport. The spill • Vehicles equipped with baffles for liquid waste. • Trucks with sealed gates and spill guards for solid waste. Loading or unloading wastes can contaminate storm water when the wastes are lost from the transfer. Loading systems can also be used to minimize spills and fugitive emission losses such as dust or mist. Vacuum transfer systems can minimize waste loss. RunonM lno I Prevention Storm water :anon should be prevented from entering the waste in area. Storm water pollution from runon can be prevented by enclosing the area or building a berm around the area. Other alternatives for reducing storm water Pollution include: • Preventing the waste materials from directly contacting rain. Industrial Handbook 4 • 32 March, 1993 LJ Additional Information— Waste Handling and Disposal • Moving the activity indoor after ensuring that all safety concerns such as fire hazard and ventilation are addressed. • Covering the area with a permanent roof. • Covering waste piles with temporary covering material such as reinforced tarpaulin, polyethylene, polyurethane, polypropylene or hypalon. To avoid tracking materials off -site. the waste management area should be kept clean at all times by sweeping and cleaning up spills immediately. Vehicles should never drive through spills. If necessary, wash vehicles in designated areas before they leave the site, and control the wash water. Minimizing the runoff of polluted storm water from land application of industrial waste on -site can be accomplished by: • Choosing a site where. slopes are under 6 percent - the soil is permeable - there is a low water table - it is located away from wetlands or marshes - there is a closed drainage system • Avoiding applying waste to the site: - when it is raining - when the ground is frozen - when the ground is saturated with water • Growing vegetation on land disposal areas to stabilize soils and reduce the volume of surface water runoff from the site. • Maintaining adequate barriers between the land application site and the receiving waters. Planted strips are panicu- larly good- 0 using erosion control techniques - mulching and matting, - filter fences. - straw bales, - diversion terracing, - sediment basins. • Performing routine maintenance to ensure the erosion control or site stabilization measures are working. Exam_. of Effective Pros me The port of Long Beach has a state-of-the-art database for. identifying potential pollutant sources, documenting facility management practices, and tracking pollutants. REFERENCES Best Management Practices for Industrial Stone Water Pollution Control, Santa Clara Valley Nonpoint Source Pollution Control Program, 1992. Publications Than Can Work For you!; California Department of Tonic Substances Control, Sacramento, CA, 1991(A list and order form for waste minimization publications from the State). Storm Water Management for Industrial Activities: Developing Pollution Prevention Plans, and Best Management Practices, EPA 832-R-92-006, USEPA, 1992. Distribute List, Pollution Prevention Information Clearinghouse, USEPA 1992. 1 SC9 i Industrial Handbook 4 - 33 March, 1993 ACTIVITY: CONTAMINATED OR ERODIBLE SURFACE AREAS Applications -F --Cr RMManufacturing Material Handling • ;.,, Vehicle Maintenance WN x .tea. scs .x. -�� :r';'.&_=• Commercial Activities Waste Containment Housekeeping Practices DESCRIPTION Targeted Constituents Prevent or reduce the discharge of pollutants to storm water from contaminated or Sediment erodible surface areas by leaving as much vegetation on -site as possible, minimizing soil exposure time, stabilizing exposed soils, and preventing stormwater runon and runoff. � Nutrients APPROACH Heavy Metals This BMP addresses soils which are not so contaminated as to exceed criteria (see Title 22 Toxic Materials California Code of Regulations for Hazardous Waste Criteria), but the soil is eroding and Floatable carrying pollutants off in the storm water. Materials Contaminated or erodible surface areas can be controlled by: Oxygen Demand ing Substances • Preservation of natural vegetation, • Re -vegetation, Oil & Grease • Chemical stabilization, • Removal of contaminated soils, or Bacteria & trruses • Geosynthetics. • For a 0 Likely to Hav quick reference on disposal alternatives for spec wastes see Table 4.1. SC1. Sign/tkant Impact 0 Probable Low or REQUIREMENT$ Unknown Impact • Cost (Capital, O&M) - Except for preservation of natural vegetation. each of the above solutions can be Implementation Requirements quite expensive depending upon the size of the area. • Maintenance Q capital costs - Maintenance should be minimal, except possibly if irrigation of vegetation is necessary. Q O&M Costs LIMITATIONS O Maintenance Disadvantages of preserving natural vegetation or re -vegetating include: O Training • Requires substantial planning to preserve and maintain the existing vegetation. • May not be cost-effective with high land costs. • Lack of rainfall and/or poor soils may limit the success of re -vegetated areas. � High 0 Low Disadvantages of chemical stabilization include: • Creation of impervious surfaces. O • May cause harmful effects on water quality. sci • Is usually more expensive than vegetative cover. Best Managemen Practices Industrial Handbook 4 - 34 March, 1993 Additional Information— Contaminated or Erodible Surface Areas Of interest here are areas within the industrial site that are bare of vegetation and therefore subject to erosion. They may or may not be contaminated from past or current activities. Activity may or may not be occurring in the area of interest. According to the State's General Industrial Activity Storm Water Permit, the SWPPP must include BMPs that deal with these situations. If the area is temporarily bare because of construction, see SC12, Building Repair, Remodeling, and Construction. Contaminated or erodible surfaces can result from the human activities such as vegetation removal, compacting or disturbing soil, and changing natural drainage patterns. Industries must identify the areas of contaminated or erodible surfaces. The areas may include: • Heavy activity where plants cannot grow. • Soil stockpiles. • Steep slopes. • Construction areas. • Demolition areas. • Any area where soil is disturbed. 'lice most effective way to control erosion is to preserve existing vegetation. Preservation of natural vegetation provides a natural buffer zone and an opportunity for infiltration of storm water and capture of pollutants in the soil matrix. By Preserving stabilized areas, it minimizes erosion potential, protects water quality, and provides aesthetic benefits. This Practice is used as a permanent control measure. Vegetation preservation on -site should be planned before disturbing the site. Preservation requires good site management to minimize the impact of construction when construction is underway. Proper maintenance is important to ensure healthy vegetation that can control erosion. Different species, soil types, and climatic conditions will require different maintenance activities such. as mulching, fertilizing, liming, irrigation, pruning and weed and pest control. Maintenance should be performed regularly especially during construction phases. Advantages of preservation of natural vegetation are: • Can handle higher quantities of storm water runoff than newly seeded areas. • Increases the filtering capacity because vegetation and toot systems are usually dense in preserved natural vegetation. • Enhances aesthetics. • Provides areas for infiltration, thus reducing the quantity and velocity of storm water runoff. • Allows areas where wildlife can remain undisturbed. • Provides noise buffers and screens for on -site operation. • Usually requires less maintenance than planting new vegetation. The measure of choice is to leave as much native vegetation on -site as possible, thereby reducing or eliminating the problem. However, assuming the site already has contaminated or erodible surface areas, there are three possible courses of action: L Re -vegetate the area if it is not in use and therefore not subject to damage from site activities. In as much as the area is already devoid of vegetation, special measures are likely necessary. Lack of vegetation may be due to the lack of water and/or poor soils. The later can perhaps be solved with fertilization. Or the ground may simply be too compacted from prior use. Improving soil conditions may be sufficient to support vegetation. If available process wastewater can be used for irrigation, see Construction Best Management Practice Handbook for procedures to establish vegetation. Industrial Handbook 4 - 35 March, 1993 Additional Information— Contaminated or Erodible Surface Areas 2. Chemical stabilization (for example ligno sulfate) can be used as an alternate in areas where temporary seeding practices cannot be used because of season or climate. It can provide immediate, effective, and inexpensive erosion control. Application raies and procedures recommended by the manufacturer should be followed as closely as possible to prevent the product from forming ponds and creating large areas where moisture cannot penetrate the soil. The advantages of chemical stabilization include: • Easily applied to the surface. • Effective in stabilizing areas. • Provides immediate protection to soils that are in danger of erosion. 3. Removal of contaminated soils is a last resort and quite expensive. The level and extent of the contamination must be determined. This determination and removal must comply with State and Federal regulations, permits must be acquired, and fees paid. 4. Geosynthetics include those materials that are designed as an impermeable barrier to contain or control large amounts of liquid or solid matter. Geosynthetics have been developed primarily for use in landfills and surface impoundments, and the technology is well established. There are two general types of geosynthetics. geomembranes(impermeable) and geotextiles(permeable). • Geomembmnes are composed of one of three types of impermeable materials: elastomers(rubbers), thermoplasics(Plastics), or a combination of these two types of materials. The advantages of these materials include: 1) the variety of compounds available, 2) sheeting is produced in a factory environment, 3) polymeric membranes are flexible, and 4) simple installation. The disadvantages include: 1) chemical resistance must be determined for each application, 2) seaming systems may be a weak link in the system, and 3) many materials are subject to attack from biotic, mechanical, or environmental sources. • Geotextiles are uncoated synthetic textile products that are not water tight. They are composed of a variety of materials, most commonly Polypropylene and polyester. Geotextiles serve five basic functions: 1) filtration, 2) drainage, 3) separation, 4) reinforcement, and 5) armoring. For more information on geosynthetics, see the reference below. REFERENCES Covers for Uncontrolled Hazardous Waste Sites, USEPA, EPA/540/2-85100Z PB87-119483, 1985. 1 SCi0 t Industrial Handbook 4 36 March, 1993 ACTIVITY: BUILDING AND GROUNDS MAINTENANCE Graphic; North Central Texas COG, 19M DESCRIPTION Prevent or reduce the discharge of pollutants to storm water from buildings and grounds maintenance by washing and cleaning up with as little water as possible, preventing and cleaning up spills immediately, keeping debris from entering the storm drains, and maintaining the storm water collection system. APPROACH Leaving or planting native vegetation to reduce water, fertilizer, and pesticide needs. • Careful use of pesticides and fertilizers in landscaping. • Integrated pest management where appropriate. • Sweeping of paved surfaces. • Cleaning of the storm drainage system at appropriate intervals. • Proper disposal of wash water, sweepings, and sediments. • For a quick reference on disposal alternatives for specific wastes see Table 4.1, SC 1 REQUIRMENTS Costs (Capital, O&M) Cost will vary depending on the type and size of facility. - Overall costs should be low in comparison to other BMPs. • Maintenance - The BMPs themselves relate to maintenance and do not require maintenance as they do not involve structures. Applications Manufacturing Material Handling Vehicle Maintenance Construction Waste Containment Targeted Constituents Sediment Nutrients Heavy Metals Toxic Materials Floatable Materials f♦ Oxygen Demand- ing Substances Oil & Grease O Bacteria & viruses Likely to Have Significant kupact O Probable Low or Unknown Impact Implementation Requirements LIMITATIONS O Capital Costs • Alternative pest/weed controls may not be available, suitable, or effective in every Q O&M Costs case. Q Maintenance 0 Training I 0 High O Low SC11 Best Managemen Practices ,Lnuustnal Handbook 4 _ 37 March, 1993 Additional Information— Building and Grounds Maintenance Buildings and grounds maintenance includes taking cane of landscaped areas around the facility, cleaning of parking lots and pavement other than in the area of industrial activity, and the cleaning of the storm drainage system. Painting and other minor or major repairs of buildings is covered in SC12 (Building Repair, Remodeling, and Construction). Certain normal maintenance activities can generate materials that must be properly disposed. Other maintenance activities can enhance water quality if they are carried out more frequently and/or in a more deliberate fashion. Pesticid /F .rtili er Management Landscape maintenance involves the use of pesticides and fertilizers. Proper use of these materials will reduce the risk of loss to storm water. In particular, do not apply these materials during the wet season as they may be carried from the site by the next storm. When irrigating the landscaped areas, avoid over -watering not only to conserve water but to avoid the discharge of water which may have become contaminated with nutrients and pesticides. It is important to properly stone pesticides and application equipment, and to dispose the used containers in a responsible manner, consistent with state regulations. Personnel who use pesticides should be trained in their use. The California Department of Pesticide Regulation and county agricultural commissioners license pesticide dealers, certify pesticide applicators, and conduct on -site inspections. Written procedures for the use of pesticides and fertilizers relevant to your facility would help maintenance staff under- stand the "do's" and "don'ts". If you have large vegetated areas, consider the use of integrated pest management (IPhO techniques to reduce the use of pesticides. Parldna.lstorm Sewer Maintenance A parking area that drains to the same storm drainage system as the industrial activity that is to be permitted must also be evaluated for suitable BMP& Storm water from parking lots may contain undesirable concentrations of oil,'grease, suspended particulates, and metals such as copper, lead, cadmium, and zinc. as well as the petroleum byproducts of engine combustion Deposition of air particulates, generated by the facility or by adjacent industries, may contribute significant amounts of pollutants. The two most appropriate maintenance BMPs are periodic sweeping and cleaning catch basins if they are part of the drainage system. A vacuum sweeper is the best method of sweeping, rather than mechanical brush sweeping which is not as effective at removing the fine particulates. Catch basins in parking lots generally need to be cleaned every 6 to 12 months, or whenever the sump is half full. A sump that is more than half full is not effective at removing additional particulate pollutants from the storm water. If the storm drain lines have a low gradient, less than about 0.5 feet in elevation drop per 100 feet of line, it is likely that material is settling in the lines during the small, frequent storms. If you have not cleaned the storm drain system for some time, check the lines as well. If they are not cleaned, the catch basins will likely be filled during the next signifi- cant storm by material that is washed from the lines. Also, install "turn -down" elbows or similar devices on the outlets of the catch basins; they serve to retain floatables, oil and grease. Clearly mark the storm drain inlets, either with a color code (to distinguish from process water inlets if you have them) or with the painted stencil of "DO NOT DUMP WASTE". This will minimize inadvertent dumping of liquid wastes. Sweepings and sediments from these maintenance activities are generally low in metals and other pollutants and there- fore can be disposed on -site or to a construction debris landfill. Test the material if there is a reasonable doubt whether metals or other pollutants are present. If concentrations of contaminants are high, it indicates that other BMPs may be needed to eliminate or reduce emissions from the source. If a vactor truck is used to clean the storm drainage system. Sc11 Industrial Handbook 4 - 38 March, 1993 s Additional Information— Building and Grounds Maintenance dirty water will be generated. This water should not be discharged to the storm drainage system as it is silt laden and contains much of the pollutants that were removed by the catch basins. The water should be disposed to the process wastewater system, if you have one, or to the public sewer if permission is granted by the local sewer authority. Alterna- tively, the water can be placed somewhere on the site where it can evaporate. The cleaning of the paved surfaces and catch basins in the areas of industrial activity has been discussed previous! in SCS (Loading and Unloading of Materials), SC7 (Outdoor Process Equipment ui ment Operations and Maintenance), and SC8 (Outdoor Storage of Raw Materials, Products, and Byproducts). If some employees have cars that are lealong abnormal amounts of engine fluids, encourage them to have the problem corrected. . F-x=les of Fff .rrivr. pr"a Information on integrated pest management may be obtained from the Bio-Integral Resource Center, P.O. Box 7414, Berkeley, CA 94707, 510-524-2467. . REFERENCES Best Management Practices for Industrial Storm Water Pollution Control, Santa Clara Valley Nonpoint Source Pollution Control Program, 1992. SCi 1 Industrial handbook 4 - 39 March, 1993 0 0 ACTIVITY; BUILDING REPAIR, REMODELING AND CONSTRUCTION Applications Graphic: North Central Texas COG, 1993 Manufacturing Material Handling o Vehicle Maintenance onstruciion Commercial Activities `> Roadways Waste Containment DESCRIPTION Targeted Constituents Prevent or reduce the discharge of pollutants to storm water from building repair, remodel- • Sediment mg+ and construction by using soil erosion controls, enclosing or covering building material storage areas. using good housekeeping practices, using safer alternative prod- Nutrients acts, and training employees. Heavy Metals APPROACH 0Toxic Materials • Use soil erosion control techniques if bare ground is temporarily exposed. See the Construction Activity Best Management Practice Handbook. Floatable Materials • . Use permanent soil erosion control techniques if the remodeling clears buildings from 0 Oxygen Demand - an area that are not to be replaced. See SC 10 (Contaminted or Erodible Surface ing Substances Areas). • Enclose painting operations, consistent with local air quality regulations and OSHA. Oil & Grease • Properly store materials that are normally used in repair and remodeling such as 0 Bacteria & Viruses paints and solvents. • Properly store and dispose waste materials generated from the activity. See CA20, signs0 Likely to HaveJ ficant /mp� Solid Waste Management. Construction Handbook. 0 Probable Low or • Maintain good housekeeping practices while work is underway. Unknown Impact REQUIREMENTS Implementation • Costs (Capital. O&M) Requirements These BMPs are generally of low to modest in cost. 0 Capital Costs LIMITATIONS Q O&M Costs • This BMP is for minor construction only. The State's General Construction Activity Storm Water Permit has more requirements for larger Q Maintenance b projects. The companion "Construction Activity Best Management Practice Handbook" contains specific Training guidance and best management practices for larger -scale projects. Hazardous waste that cannot be re -used or recycled must be disposed of by a licensed hazardous waste hauler. Safer alternative products may not be available, suitable, or effective in every case. High 0 Low Be certain that actions to help storm water quality are consistent with Cal- and Fed - OSHA and air quality regulations. S C 1 Modifications are a common occurrence particularly at large industrial sites. The activity Best Managemen Practices Industrial Handbook 4 - 4d March, 1993 Additional Information— Building Repair, Remodeling, and Construction may vary from minor and normal building repair to major remodeling, or the installation of new facilities on currently Open space. These activities can generate pollutants that can reach storm water if proper care is not taken. The sources of these contaminants may be solvents, paints, paint and varnish removers, finishing residues. spent thinners, soap cleaners, kerosene, asphalt and concrete materials, adhesive residues, and old asbestos installation. Good Housekeeping Proper care involves a variety of mostly common sense, housekeeping actions such as: • Keep the work site clean and orderly. Removing debris in a timely fashion. Sweep the area. • Cover materials of particular concern that must be left out, particularly during the rainy season. • Educate employees who are doing the work. • Inform on -site contractors of company policy on these matters and include appropriate provisions in their contract to make certain proper housekeeping and disposal practices are implemented • Make sure that nearby storm drains are well marked to minimize the chance of inadvertent disposal of residual paints and other liquids. • Do not dump waste liquids down the start drain. • Advise concrete truck drivers to not wash their truck over the storm drain. Have a designated area that does not drain to the storm drain. • Clean the storm drain system in the immediate vicinity of the construction activity after it is completed. Proper education of off -site contractors is often overlooked The conscientious efforts of well trained employees can be lost by unknowing off -site contractors, so make sure they are well informed about what they are expected to do. Painting operations should be properly enclosed or covered to avoid drift. Use temporary scaffolding to hang drop cloths Or draperies to prevent drift Application equipment that minimizes overspray also helps. Local air pollution regulations may, in many arras of the state, specify painting procedures which if properly carried out are usually sufficient to protect way quality. If painting requires scraping or sand blasting of the existing surface, use a ground cloth to collect the chips. Dispose the residue property. If the paint contains lead or tributyl tin, it is considered a hazardous waste. Mix paint indoors before using so that any spill will not be exposed to rain. Do so even during dry weather because cleanup of a spill will never be 100% effective. Dried paint will erode from a surface and be washed away by storms. If using water based paints, clean the application equipment in a sink that is connected to the sanitary sewer. Properly store leftover paints if they are to be kept for the next job, or dispose properly. . When using sealants on wood, pavement, roofs, etc, quickly clean up spills. Remove excess liquid with absorbent material or tags. If when repairing roofs, small particles have accumulated in the gutter, either sweep out the gutter or wash the gutter and trap the particles at the outlet of the downspout. A sock or geofabric placed over the outlet may effectively trap the materials. If the downspout is tight lined, place a temporary plug at the fast convenient point in the storm drain and pump out the water with a vactor truck, and clean the catch basin sump where you placed the plug. Soil/Erosion Control If the work involves exposing large areas of soil employ the appropriate soil erosion and control techniques. See the Construction Best Management Practice Handbook If old buildings are being torn down and not replaced in the near future, stabilize the site using measures described in SC10, Contaminated or Erodible Surface Areas. If a building is to be placed over an open area with a storm drainage system, make sure the storm inlets within the I SC12 Industrial Handbook 4 - 41 March, 1993 Additional information Building Repair, Remodeling, and Construction [building are covered or removed, or the storm line is connected to the sanitary sewer. If because of the remodeling a new drainage system is to be installed or the existing system is to be modified, consider installing catch basins as they serve as effective "in -line" treatment devices. See TC2 (Wet Ponds) in Chapter 5 regarding design criteria. Includein the catch basin a "turn -down" elbow or similar device to trap floatables. Recycle residual paints, solvents, lumber, and other materials to the maximum extent practical. Buy recycled products to the maximum extent practicaL. REFERENCES Best Management Practices for Industrial Storm Water Pollution Control, Santa Clara Valley Nonpoint Source Pollution Control Program, 1992 SC12 i Industrial Handbook 4 - 42 March, 1993 0 ---------------------- r__ mmw� ACTIVITY: OVER -WATER ACTIVITIES +oRn►xscncsm u►ivna ttucs ♦ anon 0 Applications Manufacturing ater/a! Handfn Vehicle Maintenance Construction Commenc/a/ Activities Roadways DESCRIPTION Targeted Constituents Prevent or reduce the discharge of pollutants to storm water and receiving waters from 0 Sediment over -water activities by minimizing over -water maintenance, keeping wastes out of the water, cleaning up spills and wastes immediately, and educating tenants and employees. 0 Nutrients APPROACH Heavy Metals ' Properly dispose of domestic wastewater and ballast water. Toxic Materials • Limit over -water hull surface maintenance to sanding and minor painting. Floatable • Use phosphate -free and biodegradable detergents for bull washing. Materials • Use secondary containment on paint cans. Oxygen Demand- 0 Have available spill containment and cleanup materials. ing Substances • Use ground cloths when painting boats on land. 0 Di! &Grease • Use tarps, plastic sheeting, etc. to contain spray paint and blasting sand. ' Properly dispose of surface chips, used blasting sand, residual paints, and other Bacteria & Viruses materials. Use temporary storage containment that is not exposed to rain. • Immediately c!k to Ham clean up spills on docks or boats. sltiG,nrlmpsct ' Sweep drydocks before flooding. 0 Probable Low or ' Clean catch basins and the storm drains at regular intervals. Unknown impact implementation • Post signs to indicate proper use and disposal of residual paints, rags, used oil, and other engine fluids.` Requirements ' Educate tenants and employees on spill prevention and cleanup. 0 Capita/ • Include a ro PP priate language in tenant contracts indicating their responsibilities. Casts • Marinas should provide wastewater disposal facilities. Q O&M Costs REQUIREMENTS Q Maintenance • Cost (Capital, O&M) O Training - Most of the BMPs are of low and modest cost. Exceptions are stations for temporary storage of residual paints and engine fluids, and wastewater pumpout facilities. • Maintenance High 0 Low - Keep ample supply of spill cleanup materials. LIMITATIONS V C 13 Private tenants at marinas may resist restrictions on shipboard painting and maintenance. Existing contracts with tenants may not allow the owner to require that tenants abide by new rules that benefit water quality. Even biodegradable cleaning agents have been found to be toxic to fish. Best Industrial Handbook -- --- — 4 - 43 March, 1993 9 Additional Information — over -Water Activities Over -water activities occur at boat and ship repair yards, marinas and yacht clubs, although the. later are not required to obtain a permit. Activities of concern include chipping and painting of hulls, on board maintenance of engines, and the disposal of domestic wastewater and ballast water. With few exceptions. BMPs to protect water quality are common sense, low cost changes to normal day -today procedures. Over -water A tivily Minimi anon Work on boats in the water should be kept to a minimum. Major hull resurfacing should occur on land. Surface prepara- lion over water should be limited to sanding. Painting should be limited to spot work. In marinas. tenant maintenance over water should be such as to not require opening more than a pint size paint can. Paint mixing should not occur on the dock. Good Housekeeuino When conducting on board maintenance, used antifreeze should be stored in a separate, labeled drum and recycled. Fuel tank vents should have valves to prevent fuel overflows or spills. Boats with inboard engines should have oil absorption Pads in bilge areas and they should be changed when no longer useful or at least once a year. Marina owners should provide temporary storage stations for used engine fluids, paint cans, and other maintenance materials. Signs should be posted at the head of each dock indicating maintenance rules. Marina owners should install a wastewater disposal system, either dockside lines or a pumpout station. Tenant contracts should include language indicating their responsibilities. When painting on shore, place paint cans in a tray or comparable device that collects spills and drips. Use ground cloths when painting. Use spray guns that minimize overspray; also enclose the area with plastic tarps. Identify a designated area for washing boats. Vacuum sweep work areas frequently. When doing repairs or painting on a tidal grid or similar Open "dry dock". use ground cloths to retain chips and spilled paint The repair yard owner should install signs so that boat owners who are doing their own work know their responsibilities. Large boat repair yards can implement the above BMPs. Tbere are several additional measures. With regard to dry dock operations: sweep the accessible areas of the dry dock before flooding; and pidc up other debris that appears after the ship is floated. Remove iloatable debris such as wood Shipboard cooling and process water discharges should be directed to minimize contact with spent abrasives, paints, and other debris. Look for and repair leaking valves. pipes, hoses, or soil chutes carrying either water or wastewater. Plastic sheeting or other suitable materials should be installed when sandblasting and spray painting. Use drip pans or comparable devices when transferring oils, solvents, and paints. Regularly clean the shoreside work areas of debris, sandblasting material, etc, Clean catch basins or other parts of the storm drainage system that might accumulate these materials. Fish Waste Fish wastes must also be managed properly. Recycling fish wastes back to the water is encouraged when disposal will not result in water quality or public nuisance problems, such as wastes washing up onshore or causing odors or bacteria problems. Fish wastes should not be recycled in any dead end lagoons or other poorly flushed areas. Marina owners should provide fish cleaning stations where waste recycling can occur without adversely affecting water quality. Now San Francisco Bay Area boat repair and maintenance facilities. The San Francisco Bay Regional Water Quality Control Board has issued a General Storm Water NPDES Permit to boat yards which work primarily on pleasure vessels less than 65 feet in length. The General Permit requires maintenance of pressure wash containment and recycle or pretreatment system implementation of a Storm Water Pollution Control Plan (SPCP) and a Monitoring Program. 1 SC13 1 Industrial Handbook 4 - 44 March, 1993 0 _._ ........a.,.,.,�.,K 4 - 45 March, 1993 0 0 . ACTIVITY: EMPLOYEE TRAINING Applications Maintenance Construction �mmerc�ialAct�ivfti" Roadways j -------------------- DESCRIPTION Employee training, like equipment maintenance. is not so much a best management practice as it is a method by which to i=1ement BMPs. 'Ibis fact sheet highlights the importance of training and of integrating the elements of employee training from the individual source controls into a comprehensive training program as part of a facility's Storm Water Pollution Prevention Plan (SWPPP). The specific employee training aspects of each of the source controls are highlighted in the individual fact sheets. The focus of this fact sheet is more general, and includes the overall objectives and approach for assuring employee training in storm water pollution prevention. Accordingly, the organization of this fact sheet differs somewhat from the other fact sheets in this chapter. OBJECTIVES Employee training should be based on four objectives: • Promote a clear identification and understanding of the problem, including activities with the potential to pollute storm water, • Identify solutions (BMPs); • Promote employee ownership of the problems and the solutions; and • Integrate employee feedback into training and BMP implementation. APPROACH • Integrate training regarding storm water quality management with existing training programs that may be required for your business by other regulations such as: the Illness and Injury Prevention Program (IIPP) (SB 198) (California Code of Regulations Title 8, Section 3203), the Hazardous Waste Operations and Emergency Response (HAZWOPER) standard (29 CFR 1910.120). the Spill Prevention Control and Countermeasure (SPCC) Plan (40 CFR 112), and the Hazardous Materials Management Plan (Business Plan) (California Health and Safety Code, Section 6.95). Businesses, particularly smaller ones that are not regulated by Federal, State, or local regulations, may use the information in this Handbook to develop a training program to reduce their potential to pollute storm water. LISTING OF INDUSTRIAL ACTnW ES Employee training is a vital component of many of the individual source control BMPs included in this chapter. Follow- ing is a compilation of the training aspects of the source control fact sheets. SC14 Best Managemen Practices Industrial Handlxrok 4 - 46 March, 1993 ACTIVITY EMPLOYEE TRAINING (Continue) SCI Non -Storm Water Discharges to Drains • Use the quids reference on disposal alternatives (Table 4.1) to train employees in proper and consistent methods for disposal. • Consider posting the quick reference table near storm drains to reinforce training. . SC2 Vehicle and Equipment Fueling • Train employees in proper fueling and cleanup procedures. • The SPCC Plan may be an effective program to reduce the number of accidental spills from fueling. SC3 Vehicle and Equipment Washing and Steam Cleaning • Train employees in standard operating procedures and spill cleanup techniques described in the fact sheet. SC4 Vehicle and Equipment Maintenance and Repair • Train employees in standard operating procedures and spill cleanup techniques described in the fact sheet. • Paint stencils to remind employees not to pour waste down storm drains. SCS Outdoor Loading/Unloading of Materials • Use a written operations plan that describes procedures for loading and/ unloading. • Have an emergency spill cleanup plan readily available. • Employees twined in spill containment and cleanup should be present during loading/unloading. •� Make sure fork lift operators are also properly trained. SC6 Outdoor Container Storage of Liquids • Registered and specifically trained professional engineers can identify and correct potential problems such as loose fittings, poor welding, and improper or poorly fitted gaskets for newly installed tank systems. • Employees trained in emergency spill cleanup procedures should be present when dangerous waste, liquid chemicals, or other wastes are handled. SC7 Outdoor process Equipment Operations and Maintenance • The preferred and possibly most economical action to reduce storm water pollution is to alter the activity. This may mean training employees to perform the activity during dry periods only or substituting benign materials for more toxic ones.. SC8 Outdoor Storage of Raw Materials, Products, and By -Products • Train employees in standard operating procedures and spill cleanup techniques described in the fact sheet. SC9 Waste Handling and Disposal • Train employees in standard operating procedures and spill dean up techniques described in the fact sheet. • Paint stencils to remind employees not to pour waste down storm drains. SCIO Contaminated or Erodible Surface Areas • Training is not a significant element of this best management practice. 1 SC14 1 maustrrat Handbook 4 - 47 March, 1993 0 0 ACTIVITY- EMPLOYEE TRAINING (Continue) SC11 Building and Grounds Maintenance • Personnel who use pesticides should be trained in their use. The California Department of Pesticide Regulation and county agricultural commissioners license pesticide dealers, certify pesticide applicators, and conduct on - site inspections. Written procedures for the use of pesticides and fertilizers relevant to your facility would help maintenance staff understand the "do's" and "don'ts". If you have large vegetated areas, consider the use of integrated pest management (IPM) techniques to reduce the use of pesticides. SC12 Building Repair, Remodeling, and Construction • Proper education of off -site contractors is often overlooked. The conscientious efforts of well trained employees can be lost by unknowing off -site contractors, so make sure they are well informed about what they are ex- pected to do. SC13 Over -Water Activities • Post signs to indicate proper use and disposal of residual paints, rags. used oil. and other engine fluids. • Educate tenants and employees on spill prevention and cleanup. • Include appropriate language in tenant contracts indicating their responsibilities. SC14 I Industrial Handbook 4 - March,1"3 4t��Fcr triw� City of Vernon Appendix B Treatment Control BMP Fact Sheet A2 S. TREATMENT CONTROL BMPs <Y>:<;., a fi•{,S} • This chapter describes specific :itM4:{{•:•fi.Y.{{}:T?;:}::•........ i�:?:w:�•:•}:•. {.?ti;.;:t};';?.:•}i};}:.,.. >.aXv`:�i: treatment control Best Management Practices (BMPs) for removing pollutants in storm water from industrial facilities. Each fact sheet contains a cover sheet with: • A description of the BMP • Suitable Applications • Instailation/Application Criteria • Requirements - Costs, including capital costs, and operations and maintenance (O&M) - Maintenance (including administrative and staffing) • Limitations The side bar presents information on which BMP considerations, targeted constituents, and an indication of the level of effort and costs to impiemem The remainder of the fact sheet Provides further information on some of all of these topics, and provides references for additional guidelines. BMP fact sheets are provided for each of the following, controls: Treatment Control BMPs TO Infiltration TC2 wet Ponds TO Constructed Wetlands TC4 Bio6lters TC5 Extended Detention Basins TCS Media Filtration TO Oil/Water Separators and Water Quality Inlets TC8 Multiple Systems There are several general principles that are applicable to all treatment control BMPs. • Priority should be given to source control: Source control BMPs are generally (but not always) less expensive than treatment control BMPs. Also, treatment control BMPs will not remove all pollutants and their removal efficiency is difficult to predict given the limited understanding as to the relationship between facility design criteria and performance. • Recognize the unique California climate: With few exceptions most storm water treatment experience has been in "wet" states where vegetation can be maintained without irrigation. In contrast, California's climate is semi -arid with the exception of the north coast. The treatment control BMPs.that require vegetative cover may not be practical for many areas of California unless irrigation is provided. Also, design criteria have emerged from research of facilities located in climates where the rainfall season is coincident with the growth of vegetation. However, in California, the wet season does not occur during the primary growth season. Caution must be used in using design criteria that have been developed elsewhere in the nation. • Design Storm Size: It is commonly thought by those unfamiliar with urban runoff quality management that design storms for sizing water quality controls should be the same as those used for the design of drainage facilities. This is not true. The damage done to a receiving water by the pollutant wash -off of a 25 Year storm (commonly used to size a Industrial Handbook 5-1 March, 1"3 LJ drainage system) is inconsequential to the Potential hydraulic damage. Of concern to water quality control are the small frequent events, smaller than the- 1-year storm, that carry the vast majority of runoff and pollutants. There is little or no incremental benefit from sizing facilities to treat the extreme events. Bare and erosive soils may affect treatment control BMps: Protection of natural watercourses requires that sediment transport not be altered for the watercourse. Therefore, consideration must be given to transport loads. In addition, many residential developments in California have open space areas covered by native vegetation. Because of the semi -arid climate, the vegetation his thin allowing for erosion during severe storms. These higher than normal sediment loads may adversely impact the performance and maintenance requirements of treatment control BNtPs. Consider the characteristics of pollutants in storm, water. The presence and concentration of pollutants is highly variable, both within and between storms. Pollutants come in two forms, particulate and dissolved Some treatment control BMPs will only remove particulates. Various vegetated BMPs such, as wet Ponds are purported to remove dissolved Pollutants as well as particulates. Vegetated treatment control BMPs have mechanisms that theoretically should also remove both forms, however, the data confirming the theory are limited and sometimes contradictory. Incorporate multiple use objectives: Opportunities abound to integrate storm water treatment needs with other management objectives such as the use of wet ponds and constructed wetlands for Passive recreation, wildlife habitat, flood detention, and ground water recharge. Maintenance is very important: All of the treatment control BMPs described in Industrial Handbook Chapter 5 are passive systems, that is, they operate without the need for mechanical or chemical systems. Nonetheless, maintenance is very important for the facilities to operate effectively. Factors to Consider: Each fact sheet lists seven general factors that are the most common considerations in selecting a treatment control BMP. In every case, all treatment control BMPs must be compatible with existing flood control objectives. - Soil: Infiltration systems must be located on suitable'soils; vegetation requires good soils; wet pond bottoms require impermeable soils. - Area Required: Most BMPs require considerable area, although some can be placed underground. - Slope: Certain BMPs cannot be placed on or near steep slopes as the ponding of water or velocity of flow may cause instability or excessive erosion. - Water Availability: BMN using Vegetation for pollutant removal may require water during the dry season. Aesthetics and safety: Where visible or accessible to the public, aesthetics or safety can be a concern with some BMPs. - Hydraulic Head: A few BMPs require a drop in water elevation which site topography may not provide. - Environmental Side Effects: Considerations for mosquito breeding, ground water contamination, as well as opportunities for aquatic wildlife and passive recreation. 5-2 March, 1993 B M P: INFILTRATION . Runoff Ar-w ter Considerations Soils tea Required Pope Water Availability Aesthetics Hydraulic Head Environmental She Effects DESCRIPTION Targeted Constituents A family of systems in which the majority of the runoff from small storms is infiltrated into the ground rather than discharged to a surface water body. Infiltration systems include: Sediment ponds, vault% trenches,dry wells, porous pavement. and concrete grids. Nutrients EXPERIENCE IN CALIFORNIA Heavy Metals _ Infiltration ponds have been used by many local jurisdictions and Carrians in the Central Toxic Materials Valley for about three decades. Floatable Materials SELECTION CRITERIA • Need to achieve hi level of Po Oxygen LancDemes F high particulate and dissolved pollutant removal. !ng Substances • Suitable site soils and geologic conditions: low potential for long-term erosion in the watershed. fi OH & Grease • Multiple management objectives (e.g., ground water recharge or runoff volume control). Bacteria & viruses LIMITATIONS Like/y to Haw Signlllcant bnpoet • Loss of infiltrative capacity and high maintenance cost in fine soils. 0 Probable Low or • Low removal of dissolved pollutants m very curse soils. Unknown Impact • Not suitable on fill sites or steep slopes. • Risk of ground water contamination in very coarse soils, may require ground water Implementation monitoring. Requirements • Should not use until upstream drainage area is stabilized. 0 Capita! Costs Infiltration facilities could fall under Chapter 15, Title 23, of California Code of Regulations regarding waste disposal to land. Q O&M Costs DESIGN AND SIZING CONSIDERATIONS Maintenance • Volume sized to capture a particular fraction of annual runoff. 0 Training • Pretreatment in fine soils. • Emergency overflow or bypass for larger storms. • Observation well in trenches. High 0 Low CONSTRUCTION/INSPECTION CONSIDERATIONS • Protect infiltration surface during construction. �� • Vegetation of pond sides to prevent erosion. • Frequent inspection for clogging during constriction. Best Managernen Practices Industrial Handbook 5.3 March, 1"3 0 $MP: INFILTRATION (Continue) M DnINANCE REQUMEMENTS • Remove sediment at capacity. uen �l cy appropriate to avoid excessive concenaations of pollutants and loss of infiltrative • Frequent cleaning of porous pavements. • Maintenance is difficult and costly for underground trenches. COST CONSIDERATIONS • Potential for high maintenance costs due to clogging. TC1 Industrial Handbook vnet�o..�3 5-4 March, 1993 0 Additional Information— Infiltration Genern Information Where conditions are suitable infiltration systems may be the preferred choice because. storm water is placed into the ground thereby reducing excess runoff and providing groundwater recharge. Infiltration systems include: • Infiltration basin which is an open surface pond or underground vault (Figure IA) Infiltration trench which is an underground chamber filled with rock, also called a rock well (Figure 1B). Dry well or vertical infiltration trench (Figure 1C) • Porous pavement both asphalt and concrete (Figure 1D). • Concrete grid and modular pavement which are lattice grid structures i;). with morass openings (Fi ure 1 grassed, pervious material placed in the g Infiltration basins are generally used for areas less than five acres but can handle tributary areas up to 50 acres if the soil is very penmeable. The other systems are suitable only for small sites of a few acres. Porous pavement and concrete grids should only be used in low traffic areas like padang areas. Studies have shown that porous pavement is strong and will last as long as conventional pavement (Reid, et al, 1982; Gburek and Urban, 1980). Experience in Florida and Maryland indicates that concrete porous pavement performs better than porous asphalt. Porous pavements and under- ground facilities may be favored at industrial sites where land is already needed for business activities. Infiltration systems should be considered where dissolved pollutants are of concern. However, satisfactory removal efficiencies require soils that contain loam. Coarse soils are not effective at removing dissolved pollutants and fine Particulates before the storm water reaches the ground water aquifer. Local jurisdictions may not feel that infiltration systems are appropriate control on industrial sites where spills of hazardous chemicals can occur. However, Spin procedures may provide satisfactory control (Chapter 4). Care should be taken when considering the multiple objectives of using infiltration systems for water quality treatment, ground water recharge, and flood control. Infiltration basins, trenches, and porous pavement can meet storm water detention require- ments. Three concerns with infiltration systems are clogging, accumulation of me and ground Infiltration systems have been used successfully on sandy soils in the Central Valley of California and Long Island, New York for many years without operational problems. In both instances the primary objectives are ground water recharge and flood control, not water quality treatment Problems can be expected with infiltration systems placed in finer soils. The State of Maryland has emphasized these systems for about 10 years where they have been installed in soils with infiltration rates as low as 0 77 inches per hour. A recent survey (Lindsey, et al., 1991) found that a third of the facilities examined (177) were clogged and another 18% were experiencing slow infiltration. Dry wells that treat roof runoff had the fewest failures (4%) and porous pavement the most M%). Dry wells may have the lowest failure rate because they only handle roof runoff. The primary causes Of failure appear to be inadequate pretreatment and Lad: of soil stabilization in the tributary watershed, as well as poor construction practices (Shaver, pets. comm.). Erosion of the slopes of infiltration ponds was a significant problem in almost half the facilities surveyed Problems have occurred in the Central Valley with facilities placed on finer soils, as in the case of Modesto. (Tulloch, pens. comm.). Based on a review of several studies of infiltration facilities in sandy and loamy soils concluded that "monitoring— has not demonstrated significant contamination _. although highly soluble pollutants such as nitrate and chloride have been Shown to migrate to ground water" (USEPA, 1991). However, pollution has been found in ground water where infiltra- tion devices are in coarse gravels (Adophson, 1989; Miller, 1987). 1. TC1 Industrial Handbook 5-5` March, 1993 Additional Information — Infiltration Site Selection Considerations (infiltration basin) • Recommended minimum preconstruction infiltration rates have ranged from 0.25 to 4 inches per hour. • One state (Ecology, 1992) has specified a maximum clay content (30%) and a minimum cation exchange capacity (5 meq). • Not less than three feet separation from seasonal high ground water, much greater distance if soils are very coarse. • Avoid steep (25%) slopes or other geologic conditions that would be made unstable by the infiltrating water. • Not less than four feet separation from bedrock. • Impact on local groundwater including recharge potential, water quality, etc. Stahre and Urbonas (1988) have presented a site selection procedure, if the site first passes the above criteria. Presented in Table IA is a point system. If the site receives less than 20 points it is considered unsuitable; more than 30 points is considered excellent. This procedure is used to enhance infiltration performance and minimize clogging. �Sla� The degree of treatment achieved by infiltration is a function of the amount of storm water that is captured and infil- trated over time. This relationship for various areas in California is shown in Appendix D. The figures in Appendix D were developed using the hydrological model STORM. The procedure to determine the volume of infiltration basin is as follows: (1) select the appropriate figure in Appendix D; (2) determine for the catchment the percentage of impervious area directly connected to the storm drain system; (3) choose a capture goal, and read the required unit basin storage (acre-ft. per acre) required for the infiltration basin {to Provide performance similar to the other treatment control BMPs in Chapter 5, a reasonable capture goal for infiltration systems is 80%.); (4) multiply this unit figure times the total acreage of the catchment and convert to cubic feet. When using the above approach to size an infiltration trench, remember to increase the volume of the trench to account for the rock. To calculate the minimum surface area of the infiltration system obtain the infiltration rate at the site using appropriate techniques. This value is then used in the following equations: Am V/Dm (1) where: Am = minimum area required (0) V = volume of the infiltration basin (ft3) Din = maximum allowable basin depth (ft) The maximum allowable depth is determined from the equation: Din = 40U12S (2) where: I = site infiltration rate in inches per hour S = safety factor The safety factor accounts for the uncertainty of whether the infiltration test measures the real infiltration rate. Recom- mendations have ranged from 2 to 10 (consult your local Soil Conservation Service Office). The coefficient of 40 refers to the recommended drawdown time in hours. This is a reasonable drawdown time, given that the average time rs, between storms during the wet season in California is on the order of 200 houexcept in Northern California where it is about 80 hours. A longer drawdown time may cause anaerobic conditions in the underlying soil or the production of algae during the warmer months that would clog the soil. A shorter drawdown time reduces the volume of the facility, but increases the required surface area. Appendix D contains figures for two drawdown times: -24 and 40 hours. In most of the State, reducing the drawdown time does not significantly reduce the volume. TC1 Industrial Handbook 5-6 March, 1993 Additional Information — Infiltration I Suggested references on the design of porous pavement include Maryland (1984) and Florida (1988). Additional design considers loco • For basins and trenches, pretreat the storm water to remove the floatables and settleable solids, particularly when placing these systems in finer soils. Pretreatment can be accomplished with any of the other treatment control BMPs in this handbook. Communities and CaiTrans have used infiltration systems in the Central Valley for more than two decades without pretreatment. Clogging has not been a problem with well maintained systems discharging to sands and courser soils. suggesting that pretreatment is of limited value. Pretreatment when infiltrating to finer soils is suggested by the experience of Maryland described previously. An infiltration facility sized only for treatment is much smaller than one sized for flood control and therefore may be more susceptible to clogging. Communities in the Central Valley (Fresno, Modesto) require a retention volume that captures the 100 year event. or about 20.000 ft3 per'impervious tributary acre. In comparison, above Equation (1) will provide a volume in the range of 2,000 0 per impervious acre. For small systems treating less than a few acres of pavement, pretreatment can be accomplished with a Type 2 catch basin and a submerged outlet. The diameter and depth of the sump should be at least four times the diameter of the outlet pipe to the infiltration system (Lager, et al- 1977). See Figure 1C. The catch basin cover should be stenciled "dump no waste". Vegetated Northers can also be used although they will not likely be feasible in industrial sites which tend to be fully utilized. Additional design considerations for hMim include: • Do not locate on fill sites, or on or near steep slopes • Energy dissipation at inlet to minimize erosion • Vegetate the slopes for the same reason • Vegetate the bottom to reduce tendency to clog with fines • Freeboard of 1 foot • Side slopes of at least 3:1 for safety, and for ease of mowing (4:1 slopes are prefered) Incorporate bypass or overflow for large events Provide dedicated access to the basin bottom (minimum 4:1) for maintenance vehicles Vegetating the slopes and bottom will be difficult unless the facility can be irrigated during the summer. Drought tolerantground cover species may be more suitable. See TC4 Biofilters for recommended species. Additional design considerations for 1SIIthes include: • Do not locate on fill sites, or on or near steep slopes • A 4 inch or 6 inch diameter observation well with locking cap, to check for loss of infiltrative capacity 6 inch sand layer or geofatxic at the bottom • Geofabric around trench walls to prevent soils from migrating into the trench rock matrix • Geofabric 12 inches below ground surface with 3/4 rock placed on top, which serves as filter for coarse solids • Backfili and filter rock should be clean washed aggregate 1 inch to 3 inches diameter • Incorporate bypass or overflow for large events • Provide dedicated access for maintenance vehicles For porous pavement, experience in Maryland suggest that asphalt pavement has continuous plugging problems and a limited life. Frequent maintenance is required. For drywells where access for maintenance is difficult if not impossible Pretreatment of the storm water is highly recommended. Such pretreatment may include biofrlters, sumps, etc. Consul- tation with the local jurisdiction regarding the design of drywells is required TC1 Industrial Handbook 5-7 March,1993 Additional Information— infiltration - ConsMX ion It is very important to protect the natural infiltration rate b using light Y g �g equipment and construction procedures that minimize compaction. Storm water must not be allowed to enter the facility until all construction in the catchment is completed and the drainage area is stabilized. If this prohibition is not feasible in particular situations, do not excavate area the facility to final grade until after all construction is complete upstream. Leave one foot of native soil in the basin which can be removed in layers as it clogs. Disking the surface frequently during this period may be beneficial. After final grading the final surface should also be disked. With trenches, make sure the rock fill does not become dirty while temporarily stored at the site. The local jurisdiction tray also specify that the infiltration rate of the facility be within a certain percentage of the preconswction rate before the facility is approved or accepted. Main-- Lmaa= inspect the facility at least annually and after extreme events. If there is still water in the pond or trench 72 hours after a storm it is time to clean the facility. A concern is restrictions on the disposal of the sediment removed from an infiltra- tion basin due to contamination. Limited studies suggest that this is not a problem, particularly if sources -control BMPs are effective. The Fresno Metropolitan Flood Control District found noticeable accumulation of pollutants in the surface layer in infiltration basins that had not been cleaned for about 20 years although the levels were still below toxic thresh- olds- The basins are now cleaned at least once every three years. Limited studies of the bottom sediments in wet and extended detention ponds indicate that toxicity limits specified by final disposal regulations are not exceeded (see TC2 Wet Ponds). Pretreatment may reduce maintenance costs by capturing gross settleable solids and floatabies in a smaller space that can be more easily cleaned. Maintenance techniques for basins include rototilling, disking and deep ripping. Porous pavement should be cleaned at least quarterly by vacuum sweeping and high pressure washing. See Mazy (1984) and Florida (1988) for additional guidance on the design, construction, and maintenance of infiltration systems. REFERENCES Adolphson Associates.1991, "Subsurface Storm Water Disposal Facilities", Interim Report, for the Tacoma -Pierce County Health Department. Adoiphson Associates, 1989, "Storm Water Evaluation, Clover/Chambers Basin Ground Water Management Program" for the Tacoma -Pierre County Health Department. Feld, R. H. Masters, and M. Singer, 1982, -Status of Porus Pavement Research", Water Resources Research, 16, 849. Florida (State of), 1988, "The Florida Development Manual", Department of Environmental Regulation. Goforth• G.F., J-P- Heaney, and W.C. Huber, 1983, "Comparison of Basin Performance Modeling Techniques", Jour. EE. ASCE, 109(5), 1082. Gburek, W. J, and J.B. Urban, 1980, "Storm Water Detention and Ground water Recharge Using Porous Asphalt -Initial Results", in Proceedings of International Symposium on Urban Storm Water Runoff, Lexington, Kentucky. King County, 1990, "Surface Water Design Manual", King County Washington. TC1 e..K Industrial Handbook 5-8 March, 1993 0 Additional Information — Infiftration Lindsey, G., L. Roberts, and W. page, 1991, "Stormwater Management Infiltration Practices in Maryland; A Second Survey", Maryland Department of the Environment. Maryland (Stateof), 1984, "Standards and Specifications for Infiltration Practices" Department of Natural Resources. Metropolitan Washington Council of Governments (MWCOG), March, 199Z "A Current Assessment of Urban Best Management Practices: Techniques for Reducing Nonpoint Source Pollution in the Coastal Zane". Miller, S„ 1987, "Urban Runoff Quality and Management in Spokane' in proceedings of the Northwest Nonpoint Source Pollution Conference, March 24-25, Seattle. Portland Cement Pervious Pavement Manual. Florida Concrete Products Association, Inc., 649 Vassar Street, Orlando, Florida, 32804 (no date). Schueler, TR.,1987, "Controlling Urban Runoff: A Practical Manual for Planning and Designing Urban BMPs", Metro- politan Washington Council of Governments. Shaver, E., pers. comm„ State of Delaware Department of Natural Resot rcm Stahre, R and Urbonas, B,1989. "Swedish Approach to Infiltration and Percolation Design". Quality Control, Americans Society of Civil Engineers, in Design of Urban Ruff Tullocb, Alice, pens. comm. City of Modesto Public Works. United States Environmental Protection Agency (USEPA), 1991, "Detention and Retention Effects on Groundwater", Region V. Industrial Handbook 5-9 March, 1993 I Additional Information — infiltration TABLE 1A. POINT SYSTEM FOR EVALUATING INFILTRATION SITES 1. Ratio between tributary connected impervious area (AIMP) and the infiltration area (ARM: • AINF > 2 AIMP 20 points • AIMP < AINF < 2 AIMP 10 points • 0.5 AIMP < AINF < AIMP 5 points 2. Nature of surface soil layer. • Course soils with low ratio of organic material 7 points • Normal humus soil 5 points . • Fine grained soils with high ratio of organic material 0 points 3. Underlaying soils: • If the underlaying soils are courser than surface soil, assign the same number of points as for the surface soil layer assigned under item 2 above. • If the underlaying soils are finer grained than the surface soils, use the following points: • Gravel, sand of glacial till with gravel or sand 7 points • Silty sand or loam 5 points • Fine silt or clay 0 points 4. Slope (S) of the infiltration surface: • S < 0.07 ft/ft 5 points 0.07 < S < 0.20 fdit 3 points • S > 0.20 ft/ft 0 points 5. Vegetation cover. • Healthy natural vegetation cover 5 points • Lawn is well established 3 points • Lawn is new 0 points • No vegetation, bare ground -5 points 6. Degree of traffic on infiltration surface: • Little foot traffic 5 points • Average foot traffic (park, lawn) 3 points TC1 • Much foot traffic (Playing fields) 0 points Industrial Handbook S - 10 March, 1993 Top View Additional Information -- infwawn _Embankment r Flat Basin Floor with Oense Grass Turf •t • Inlet : . ;;6.= Riprap �Y • Settling �,:',•:"r. Basin and level Spreader Riprap Outfall \ • ; s r-- :„��:"•• J Protection Back-up Underdra#n Emergency Spillway i Side View . valve''i! ltlt=.tl�lltl //aTt111=!,fluff �i 111t=11�j11} %�i H11=%�it1=�i \ilTi2 N,1=(tlluil�i�,. Back-up Underdrain Pipe in Case at Standing Water Problems Souoe: Schueier (1987) NOTE: 1. Backup underdrain is not used in most applications because plugging occurs in soil above the drain. 2. An infiltration basin can also be excavated (typically 2 to 6 feet deep) as long as the bottom of the basin is 3 feet above high seasonal water table. FIGURE 1A. INFILTRATION BASIN TC1 Industrial Handbook 5 11 March, 1"3 0 Additional Information — mt=ion MEDIAN STRIP DESIGN Top View Side View Inflow 20* Grass Filter Strip Grass _F0 - - •Sides Lined with Permeable Filter Fabric Permeable Filter r Fabric One Foot Clean washed Stone or Gravel Below Surface. (1.5-3.0 Inch) Traps Debris ............... -12 Inch Sand Filter or Permeable Filter Screened Overflow Pipe Cloth Lines Bottom Outflow Source: Schueler (1987) BUILDING DRAIN DESIGN fRoof Drain ,Observation Well Splash Block Sheet Cover Mat'l. Pule Adapted from King County r4 .--,,Mesh Level Screen CB, Sump with Perforated Pipe sow Lid - Optional TC1 FIGURE 1B. INFILTRATION TRENCHES P,'-ee.. I 5-12 March, 1993 Additional Information 1- a' PVC seer pope .Z.— ,.. Concrete Mannole •:•y • 9•-93- Mannae to oe aertaratea +��C• 'n area of prljei OCM 48' Ip PreeOstulottnde ,ntn bottom 1 Prtoroted Montvale tiled as sno-n - 700 of prc m Racx 1 itn 1 1/2' to 3- -ashed brain Rawl j Manhole_ has open bottom Fill over-escovotod area with drain rack 4--0- 1 l/2' to 3- -0sned Drain Roc. 3' PVC c0d*ction pipe, drill y » +.:. • 3/4' holes a 2' ete, top of awe - Source: Adoiphson, 1991 WITH PRETREATMENT ` . 1 ROW 6eee.r Side view i 1 o•erno. Pro. 1 1 SWean floe. Call ,.-m III 11 i 1 •. • ::, f / � locnes :o 3rv+.ea 1 ory wee ..1 yQ .�i `:--p: C. aC ..%• .e .-_�i1 ..' 1 InNf Pw. •b'.o—%�.wr3en_%,::i. - 1. o•:A� • 0-ter FaunrnZ.r. • %� --� v •. Es saftem Sop Q tones toe^t1 r rjj 0�,..0 %-1 . O Sopas of pry • :� v`i.�:7 a vigil pouncanon / Stone FiN is ! s$� .r a-. o •.?. Tiltwgit Often a�'�' (^sir'' ;P • • �• M� of Pertorstea Q•• t L•«�° % -'' •' ..:• Pam-. 9I0e. a•CS�a oo.o; a ^ aa.000•0 Aecnoredw-m e •. av • •• Reasr e 0, • • l0ioat .•O:.r3;dd:�.Ae.. „ . .d.�r0: Z-�:e`'p� Source: Schueier, 1987 Note: See discussion on page 5-6 regarding design considerations. TC1 WMOUT PRETREATMENT FIGURE ICDRYWELL CONFIGURATIONS °"' Industrial Handbook 5 - 13 March, 1993 Additional Information — Infutrawn W y t N , o w C y n Q.q as L6 CM N •"' .. q i CJ wCM -` Cn on J X W y W W— 4II "� +• �N q VN CM Ql O N �O C ^ O O CZn r iti CO G'1 v O - C O V1 ti y •._� iW 1� S N _� ccN C. K f N W "� p O N C U ? i� ��J V2 7= O L O♦ N a ^4 q N JxrL. .-r N LLJ O- C •--� ? L � L ILL.. j W � C T ♦ v �► c q z Y ASWA O O 0 U 0 J p.y z h a Q a A rl W TC1 I Industrial Handbook 5 - 14 March, 1993• IF� Additional Information -wiftration ro"mWoos - L Poured -in -Place Slab Lattice Unit Source: State of Florida Castellated Unit noauiar unit FIGURE 1E. TYPES OF GRID AND MODULAR PAVEMENTS TC1 a..e Industrial Handbook 5 15 March, 1993 0 0 (� BMP: WET PONDS rA l S Considerations soils Hydraulic Head Environmental Side Effects DESCRIPTION A wet Pond has a Targeted Constituents Po permanent water pool to treat. incoming storm water. An enhanced wet Pond includes a pretreatment sediment forebay 0 Sediment ii CALIFORNIA EXPERIENCE ' Q Nutrients There are regional flood control basins in California that function like wet ponds or Q Heavy Metals constructed wetlands OM). Q Toxic Matedals SELECTION CRITERIA !♦ Floatable Malaria/s • Need to achieve high level of particulate and some dissolved contaminant removal • Ideal for large, regional tributary. areas. Q Oxygen Demand • Multiple benefits of passive recreation (e.g., bird watching, wildlife habitat). ing Substances LIMITATIONS Q Oil & Grease • Concern for mosquitoes and maintaining oxygen in ponds. • Cannot be placed on steep unstable slopes. • Need base flow or supplemental water if water level is to be maintained • Infeasible in very dense urban areas. • In California the wet season is coincident with minimal plant growth. Could be regulated as a wetlands or under Chapter 15, Title 23, California Code of • Regulations regarding waste disposal to lands. • Pending volume and depth, pond designs may require approval from State Division of Safety of Dams. Q Bacteria & Viruses iJkel to Haw swflCant Impact >e ice' or p act Implementation Requirements DESIGN AND SIZING CONSIDERATIONS • Wet pool volume determined by Figures ZB and C C. • Water depth of 3 to 9 feeL • Wetland vegetation, occupying 25-50% of water surface area. • Design to minimize short-circuiting. • Bypass storms greater than two year storm. Q Q Capital Costs O&M Costs Maintenance Training CONSTRUCTIONANSPECTION CONSIDERATIONS • Be careful when installing wetland vegetation. High Low MAINTENANCE REQUIREMENTS • Remove floatables and sediment build-up. • Correct erosion spots in banks. TC2 • Control mosquitoes. • May require permits from various regulatory agencies, e.g. Corps of Engineers. COST CONSIDERATIONS Best Costs for providing supplemental water may be prohibitive. • Y p Managemen Practices Industrial Handbook 5 -16 March, 1993 Additional Information — wet Ponds - rtt� The major features of a wet pond are shown in Figure 2A. It is essentially a small lake with rooted wetland vegetation along the perimeter. The permanent pool of water provides a quiescent volume for continued settling of particulate contaminants and uptake of dissolved contaminants by aquatic plants between storms. The wetland vegetation is present to improve the removal of dissolved contaminants and to reduce the formation of algal mats. However, given the need to minimize the impact on space, it maybe cost-effective to use vertical concrete retaining walls which would not allow for emergent vegetation. The average depth of the wet pool is generally 3 to 9 feet, although greater depths are pth possible with artificial mixing. The objective is to avoid thermal stratification that could result in odor problems. Gentle artificial mixing may be needed in . small ponds because they are effectively sheltered from the wind In industrial applications ground water or treated process water will have to be pumped into the facility to maintain the water leveL The wet pond could be allowed to dry during the summer months. Allowing the wet pond to dry has not been tried elsewhere but seems feasible since the pond need not operate during the summer months. The major problem with this concept will likely be aesthetics rather than performance. Wet ponds ace of interest where the removal of the dissolved constituent fraction is of concern, particularly nutrients and metals. Dissolved contaminants are removed by a combination of processes: physical adsorption to bottom sediments and suspended fine sediments, natural chemical flocculation, and uptake by aquatic plants. A wet pond with &nerete sides and floor would therefore not likely provide any advantage over the non -vegetative treatment control BMPL The > JWve importance of each mechanism is not well understood. Very limited data prevents a definitive conclusion as to the effectiveness of wet ponds in removing dissolved contaminants. Reduction in the dissolved fraction of phosphorus and some metals have been observed but this does not necessarily mean it is removed in the pond It may be incorpo- rated into algae or absorbed onto fine particulate matter which exits the facility in the effluent. If the primary removal mechanism is biological, wet ponds may not be particularly effective in removing dissolved contaminants in California because most storms occur during winter when plant growth is minimal, Another concept is the extended detention wet pond in which the outlet of the facility is restricted so as to retain a treatment design storm on top of the wet pool for a speed time. It is believed this added measure improves perfor- mance- The effect of restricting the outflow is to reduce the overflow rate during the storm increasing the capture of settleable solids. However, the majority of settling occurs between rather than during the storms. The extended deten- tion zone may therefore provide little incremental benefit. If vertical space is available the concept could be employed because the added cost may be nominal. See TO Extended Detention Basins on how to determine the extended deten- tion volume. Desien Two methods have been proposed for the sizing of wet ponds: one predicated on the removal of particulate contaminants only (USEPA,1986) and one predicated on the removal of phosphorus as well (Florida, 1988; Maryland,1986). The first method relates the removal efficiency of suspended solids to pond volume. The second method provides a detention time of 14 days based on the wettest month to allow sufficient time for the uptake of dissolved phosphorus by algae and the settling of fine solids where the particulate phosphorus tends to be concentrated. The criterion of 14 days comes from Kast et aL, 1983 who observed that in lakes at least 14 days is needed for significant algal growth during the growing season. In much of the United States including Maryland and Florida the growing season is coincident with significant rainfall. But this is not the situation in California where essentially all of the rainfall occurs from November through April. Consequently, the removal of phosphorus and fine solids will not be as high as the literature indicates. 1 TC2 1 Industrial Handbook S - 17 March, 1993 Additional Information— wet Ponds Sizing the Permanent pool Figure 2B shows the relationship between performance and the long-term removal efficiency for average conditions in California (USEPA (1986) as adapted in FHWA (1989)).. Vb/Vr is the ratio of the volume of the wet pond to the volume of the runoff of the mean storm event from the tributary watershed. The depth of the mean storm for various areas of California is shown in Figure 2C. The recommended performance goal is 80%. The volume of the pond is therefore calculated as follows: Vb = 3Sd Ai 43560/12 = 10890SdAi (1) where: Vb = pond volume (ft3) Sd = mean storm depth (inches) Ai = impervious acres in the tributary watershed For Ai the engineer may use directly connected impervious acres because it more correctly represents the area being treated and would allow a smaller facility. Although impervious area and directly connected impervious area are not the same, they are reasonable given the uncertainty of the methodology and expected pond performance. This volume should be compared with the 14 days detention time criterion and the more conservative volume (e., larger volume) should be used for sizing. Adding Detention Storage to •tip Permanent Pool Some investigators believe that detention volume added above the permanent pool enhances pool performance. The State of Florida, for example, requires one basin inch of detention storage be added to the permanent pool and be bled down over a 60 hour period. This requirement,. however, adds considerably to the size of the basin, and the literatm does not indicate that water quality performance is improved. Therefore detention storage should be added only if the pond is to be used for drainage control in addition to water quality control. As with extended detention, consideration Should be given to bypassing the facility for flows greater than the two year storm so that bed load is not trapped in the 1?ond- A perforated riser outlet recommended by the Denver Urban Drainage and Flood Control Districts is illustrated in Figures 2D and 2E. Other outlet concepts are illustrated in T C5, Extended Detention Basins, Figure 5B. Additional Considerations • Place wetland vegetation around the pond perimeter and near the outlet. Rooted vegetation around the pond perimeter serves several functions (Figure 2A). It enhances the removal of dissolved Pollutants (see 13, Constructed Wetlands); it may reduce the formation of floating algal mats: it reduces the risk of people falling into the deeper areas of the pond; and, it provides some habitat for insects, aquatic life, and wedand wikltife. The "shelf' for the vegetation should be about 10 feet wide with a water depth of 1 to 2 feet. The total area of the "shelf' should be 25-5D% of the water surface area. Vegetation near the exit will assist settling of solids. An alternative is a rock filter which is used in many wastewater oxidation ponds where loss of algae in the effluent is a common problem during the growth season (Rich, L.. 1988). If mesquites are of particular concern, it would be advisable to inhibit the growth of emergent wetland vegetation around the perimeter by using steep slopes, say, 2:1, and by minimizing the amount of pond area that has a depth less than IS". Gambusia (mosquito fish) can also be planted in larger ponds but the water level must be maintained to insure their survival during the dry season. TC2 I Industrial Handbook 5 - 18 March, 1993 Additional Information — Wet Ponds If placement of wetland vegetation along the perimeter is not feasible consider the use of devices that retain non -rooted wedand species (Limnion, undated; Zirschky, et al, 1980). Non -rooted vegetation is more effective than rooted vegeta- tion in removing dissolved nutrients and metals (see TC3 Constructed Wetlands). The vegetation grows within the device which is periodically removed and cleaned [hereby removing the contaminants from the facility. The system developed by Limnion is in use in several artificial lakes in California to control nutrients. ' Except for very small facilities, include a forebay to facilitate maintenance. • Use side sloes of at least 2:1 or flatter unless vertical retaining walls are used • Except for very small facilities, provide access to the forebay (slope of 4:1 or less), to the outlet, and around the Pond perimeter for cleaning. About 10 to 25% of the surface area determined in the above procedure should be devoted to the forebay. The forebay can be distinguished from the remainder of the pond by one of several means: a lateral sill with rooted wetland vegeta- tion, two ponds in series, differential pool depth, rock -filled gabions or retaining wall, or a horizontal rock filter placed laterally across the pond. • Use energy dissipation at the inlet to avoid erosion, to promote settling in the forebay and to minimize short- circuiting. • Use a length to width ratio of at least 3:1 to minimize short -circuiting - Short circuiting must be minimized. This can be accomplished by using a generally rectangular configuration with a length to width ratio of a least 3:1 and by placing the inlet and outlet at opposite ends. The inlet and owlet can be placed at the same end if baffling is installed to direct the water to the opposite end before returning to the outlet If topography or aesthetics requires the pond to have an irregular shape, the pond area and volume should be increased to compensate for the dead spaces. Inlet design may affect a facility's hydraulic efficiency. The traditional approach of deadheading the inlet pipe directly into the pond's not satisfactory. Experience with wastewater treatment indicates that it is best to have multiple inlets spaced equal to the depth of the pond, with a perforated baffle located in front of the inlets at a distance from one to two times the pond depth (Kleinschmidt, 1961). However, this concept is not practical with storm water treatment systems. A possible compromise that should significantly reduce short-circuiting in which the flow is split by a T or Y (Kleinschmidt. 1961) with the horizontal rode filter serving as perforated baffle. A lateral bench with wedand vegetation as shown in Figure 2A should also work The area between the inlet and the filter becomes the forebay. Placing large rocks at each inlet will dissipate the energy and spread the water more effectively across the forebay. • Minimize water loss by infiltration through the pond bottom. To maintain the wet pool to the maximum extent possible excessivelosses by infiltration through the bottom must be avoided. Depending on the soils, this can be accomplished by compaction, incorporating clay into the soil, or an artificial liner. • Freeboard of 1 foo. • With earthen walls, place an antiseep collar around the outlet pipe. ' The outlet should incorporate an antivortex device if the facility is large (A 100 year storm must safely pass through or around the device). The settleable solids concentration of storm water is relatively low, obviating the need for adding depth to the facility for sediment storage. TC2 Industrial Handbook 5 , 19 March, 1993. • A Additional Information — Wet Ponds The sides of an earthen wall should be vegetated to avoiderosion. Drought tolerant groundcover species should be used if irrigation can not occur during the summer. See TC4, Biofilteis regarding recommended plant species. Maintenance Check at least annually and after each extreme scorn event The facility should be cleaned of accumulated debris. The banks of surface ponds should be checked and areas of erosion repaired. Remove nuisance wetland species and take appropriate measures to control mosquitoes. Solids should be removed when 10 to 15% of the storage capacity has been lost. Limited studies (Dewberry and Davis, 1990; Meiorin, 199 1; Florida, 1991; Livingstone, pers. comm.) of the bottom sediments indicate that toxicity limits specified by final disposal regulations are not exceeded. Concentrations observed by Dewberry and Davis (1990) were less than 1/1000 of toxicity limits. If this problem is occurring it suggests that source control BMPs need to be improved If algal blooms are excessive consider alum treatment or the use of devices that retain non -rooted vegetation as dis- cussed above. REFERENCES Dewberry and Davis Inc, 1990, "Investigation of Potential Sediment Toxicity from BMP Ponds", Northern Virginia Planning District Commission. Florida (State of), 1988. "The Florida Development Manual", Department of Environmental Regulation. Florida (State of), 1991, "Maintenance Guidelines for Accumulated Sediments in Retention/Detention Ponds Receiving Highway Runoff", Department of Transportation. Kleinschmidt, S.R.,1961. "Hydraulic Design of Detention Tanks", J. Boston Society of Civil Engrs., 48. 4, 247. Limmon Corporation, undated, "Nutrient Removal Using a Submersed Macrophyte System~, and "Metals Removal Using a Submersed Mactophyte System". Maryland (State of), 1986, "Feasibility and Design of Wet Ponds to Achieve Water Quality Control", Water Resources Administration. Metropolitan Washington Council of Governments (MWCOG), March, 199Z "A Current Assessment of Urban Best Management Practices: Techniques for Reducing Nonpoint Source Pollution in the Coastal Zone". Rant, W., R. Anne Jones, G. Fred Lee,1983, "Predictive Capability of U.S. OECD Phosphorus Loading Eutrophication Response Models", J. Water Pollution Control Federation, 55, 7, 990. Rich, L, 1988, "A Critical Look at Rock Filters", J. of Envir. Engr, Amer. Society of Civil Engrs, 114, 219. Shepp, D., D. Cole, and F. Gaili, 1992. "A Feld Survey of the Performance of Oil/Grit Separators", Metropolitan Council of Governments. United States Environmental Protection Agency, 1986. "Methodology for Analysis of Detention Basins for Control of Urban Runoff Quality". TC2 Industrial Handbook 5 - 20 March, 1993 ----_ �.........,.,� 5 - 21 March, 1993 a Additional Information — wet Pods a LU uj Lei= 1 to !j i. I � 6 -I 0 .2 "'�i w o 0 Z C3 N � � m • O I 0 Z C n 0 Lt m o c 3 G s a a cv �� • Z i a O uj i E � �• = r Q � r Tm 0'0 1 .�.t N 3� o c Q.9� •q w o` m LU C �4 N LL C) a z �m m Q O O Z LU J V O- U � � uz A C m a e z c o J �N] coo 1 TC2 1 Industrial Handbook 5 - 22 March, 1993 im-5 rlas nana000K 5 - 23 Match, 1993 • Additional Information -wet Ponds 0.60 0.50 0.40 Del 0.50 FIGURE 2C. AVERAGE STORM EVENT TC2 DEPTH (INCHES) _ ; Industrial Handbook 5 24 March, 1993 Additional Information — wet Ponds Threaded Cac Reftxrvaolo & Locxacio Overflow Grate far` Larger Storms Detention Volume 0 Level cr Perforated !-Ides Above Permanent Pool *n Pwmla-ent Pool Level 2 feet Ll Perrnanerit Poof Trash es F SkkTwner See oew Stiff Steil Screen for Trasa Skimmer ver pCoen on Too Bottom Rs a 40 of Riser Pend Somorn Oran %4we Water Quality -1 \2L:-J- AmosPit— Outlet Pipe—. Riser Pipe (too 0Stan \I'-- -T- (min. 3 to . . . . . . . . . . . Notes-. t. AJUwr%We designs am a=eoxablo as long as the nyor 'u,,cs provides the required om" tirnwit. 2. Use Mesh Shimmer screens of so green U" m3tw'21 w ProtOot Pwtcw3wd riser. Size Must extend from the 100 of the riser M 2 IL below to Base to Prevent: OUTLET WORKS Hydrocatic Uplift perinanent pool jev*L NOT TO SCALE Nchm- 1. Wu*nuin nmbw of hoies- a 2. A4nwnwn hole diameter . iAr cia. -1 M* diameter Air era in Threaded Cao Water Cluafity Outlet Holes Ductile Iran or Steel Pipe ,-ER OUALITY RISER PIPE NOT TO SCALE (Used By Permission, UDFCD, 1992) Maximum Numcw Of Pwf=wd Cakonns Faw Hole Oiamoter. kx:tws Oiameter Ile tir w 0M) 4 6 12 12 9 is 16 12 to 20 20 1 14 1 10 12 24 I 24 1 IS 12 NC40 oiamebw j Area 2) 1/8 0.013 1/4 0449 341 (Lila 1/2 0.196 sla 0.307 314 0.442 718 0.601 I o.78s FIGURE 2D. WATER QUALITY OUTLET FOR. A WET POND I TC2 I ludustrW Handbook* 5-25 March, 1993 I 4 2 0.1( 0.01 0.0f .._ Additional Information — wet Ponds I FAA EPA �/JIIEIII�� '�I 0.011 4.0 6.0 8.0 10 20 40 60 Required Area per flow (u1.2 ) Sourm Douglas County Stoat Drainage and Technical CnireriL 1986. (Used By Perm ion. UDFM. INN FIGURE 2E. WATER QUALITY OUTLET SIZING: TC2 WET POND WITH A 12-HOUR DRAIN ITME OF THE CAPTURE VOLUME Industrial Handbook 5 - 26 March, 1993 • BMP: CONSTRUCTED WETLANDS FLOW AQUATIC PLANTS Considerations Soils Area Required Slope Water Availability Aesthetics Hydraulic Head Environmental Side Effects DESCRIPTION Constructed wetlands have a significant percentage of the facility covered by wetland vegetation. EXPERIENCE IN CALIFORNIA Research facility constructed in Fremont in 1983 by the Association of Bay Area Govern- ments. Several communities (Davis, Orange County) have regional detention ponds that are essentially constructed wetlands. SELECTION CRITERIA • Need to achieve high level of particulate and some dissolved contaminant removal. • Ideal for large, regional tributary areas. • Multiple benefits of passive recreation and wildlife. LROTATIONS • Concern for mosquitoes. • Cannot be placed on steep unstable slopes. •. Need base flow to maintain water level. • Not feasible in densely developed areas. • Wet season coincident with minimal plant growth. • Nutrient release may occur during winter. • Overgrowth can lead to reduced hydraulic capacity, • Regulatory agencies may limit water quality to constructed wetlands. • May be regulated under Chapter 15, Title 23, California Code of Regulations regard- ing waste disposal to lands. DESIGN AND SIZING CONSIDERATIONS • Suitable soils for wetland vegetation. • Surface area equal to at least 1% and preferably 2% of the tributary watershed. • Foamy. CONSTRUCTIONANSPECTION CONSIDERATIONS • involve qualified wetland ecologist to design and install wetland vegetation. • Establishing wetland vegetation may be difficult. MAINTENANCE REQUMEMENTS • Remove foreign debris and sediment build-up. • Areas of bank erosion should be repaired. • Remove nuisance species. • Control mosquitoes. Industrial Handbook 5.27 Targeted Constituents Sediment Nutrients Heavy Metals Toxic Materials Floatable Materials i♦ Oxygen Demand- ing Substances Oil & Grease Q Bacteria & Viruses Ukely to Have Slgmtleant Impact ! Probable Low or - Unknown Impact Implementation Requirements Capital Costs Q mm Costs Q Maintenance O Training High O Low TC3 Best Managemen Practices March, 1993 BMP: CONSTRUCTED WETLANDS (Continue) COST CONSIDERATIONS • Wedlands being shallower than wet ponds may result m larger area requirements. • Costs for providing supplemental wader may be prohibitive. TC3 Industrial Handbook 5 -28 March, 1"3 i 1 0 - Additional Information— Constructed wetlands General Information Although natural wetlands are being used to treat storm water, regulatory agencies do not favor this use. except as a final "Polishing" step after treatment by one or more of the treatment control BMPs presented in this chapter. Constructed Wetlands in contrast, are built specifically for treating storm water runoff. They are not wetlands created as mitigation for the loss of natural wetlands. Consequently, there is no intention to replicate the complete array of ecological func- tions of a wetland (e.g., the presence of wildlife), although it can be done. A constructed wetland is generally one of the more aesthetic than the treatment systems. It is likely that constructed wetlands will be used only in very large industrial sites, but small facilities with concrete retaining walls to conserve space will also likely be effective. The simplest form of a constructed wetland includes a rectangular basin with a forebay and wetland vegetation area. The deeper forebay (3 to 6 feet) traps floarables and the larger settleable solids, facilitating maintenance as well as protecting the wetland vegetation. Alternatively, a detention pond may be placed before the wetland, to remove settleable solids and to protect the wetland from extreme increases in water elevation. The wetland vegetation is placed in a shallow pool that extends laterally across the basin. Construction of low flow channels through emergent vegetation can cause storm water to short circuit through channels rather than through the wetland vegetation. Placing rooted wedand species through the majority of the facility adds to the cost, in comparison to a wet pond How- ever, it is believed by many practitioners that the vegetation improves performance. Placing the vegetation across the facility as illustrated in Figure 3A improves settling of particulates and uptake of dissolved contaminants. As the constructed wetland is shallower than a wet pond, there may be better contact between the water and soil which may be the primary remover of dissolved phosphorus and metals. The vegetation reduces the effect of wind which can cause significant short-circuiting in a wet pond. Water loss in a wetland may not be greater and possibly less than a wet pond. Evapotranspiration from the plants will be greater in a wedand but evaporation from the water surface may be less because the dense vegetation eliminates the effect of the wind. The net result may be a slower rate of water loss. Conceivably a constructed wetland could be made smaller than a wet pond, given the benefits of the vegetation. But experience is too limited to identify how the size might be altered from what is calculated for a wet pond. Relying on volunteer plants to cover the vegetated area will delay complete coverage for several years and may allow the invasion of undesirable species or dominance by one or two species such as cattails which tend to flourish in disturbed Conditions. Complexity is promoted by varying water depth through the vegetated area rather than keeping the depth tmiform. Preferred species to maximize the removal of dissolved metals are Salicornia Pacifica (cadmium, copper and lead). Justicia americana (copper), Potamogeton cnspus (cadmium), Phmgmites communis (zinc), Carex stricta (zinc), and Scirpus lacustris (zinc) (Silverman, 1982). ?hen is some question as to the incremental benefit of wetland vegetation in California, inasmuch as most of the wet season occurs when the vegetation is dormant. The minimum desirable temperature for cattails, sedges, and bulrushes is IOoC, 140C, and 160C, respectively (USEPA, 1988). For most of California, mean temperatures during the winter months are 5 to IOoC; along the south coast they range from IOoC to 150C. The primary removal mechanisms for dissolved phosphorus and metals are adsorption by the soil and use by non -rooted vegetation. Rooted vegetation obtains nutrients from the soils, not from the water, unless the vegetation is placed in gravel. In contrast non -rooted vegetation removes nutrients and metals from the water (Guntenspergen, et al, 1991). It can be expected that soil adsorption will continue during the winter to some extent Removal of metals and nutrients by non -rooted vegetation may not occur, or will at least be signifrcandy reduced because of the lack of growth. In contrast, loss will occur from vegetation die -off or dormancy. The net effect over a 12 month period may be that a constructed wetland is no more effective than a wet Pond, particularly with regard to the removal of dissolved phosphorus and metals. TO 1 Industrial Handbook 5 - 29 March, 1993 Additional Information — Constructed Wettands The above concern is partially confirmed by research at the experimental wedand/wet pond in Fremont (Meiorin, 1991). The author states that the "uptake of nutrients ... was low because most storms occurred in winter when plant growth was reduced by ambient temperatures, short day lengths and low light levels". Despite the use of the word "low", phospho- rus removal during the winter months was about 50% which is not noticeably better than removal in a wet pond. The removal of nitrogen was negative. Resuspension of plant material and detritus also occurred during the winter. Despite the concerns, the wetland bottom soils are possibly a more significant mechanism for removing phosphorus and metals. However, the experience with constructed wetlands treating wastewater seems to indicate phosphorus removal occurs in the first two to three years but then removal rates decrease dramatically and have become negative in some cases (Faulkner and Richardson, 1991). This result appears to be due to saturation of the soil and the plants reaching maximum density. However, metals removal may continue. Nitrogen removal does not degrade over time because it is a bacteriological process. This process is very temperature dependent and therefore would be expected to be lower in the winter. Using gravel as the substrate may be a suitable approach in small facilities. Because the gravel is lacking in nutrients certain emergent species will take their nutrients from the water ((but, 1988). See Reddy and Smith (1988). Harvesting may also be more practical with this approach. Of Particular concern in many areas of California will be mosquitoes. Thick stands of emergent vegetation provide an ideal breeding habitat. N Gambusia (mosquito fish) are introduced into the facility the design must include a deep pool area where the fish can reside during the dry season. The forebay can serve this function. Desiyn In the most comprehensive review to date of wetlands treating storm water, Stecker et al. (1992) found considerable variation in the performance of 26 facilities, both natural and constructed. All were located on large watersheds with mixed land uses, not industrial sites. There appeared to be no relationship between performance and the size (surface area) of the wetland. The surface area of the ten constructed wetlands varied from 03% to 12.6% of the tributary area. The removals of suspended solids and phosphorus ranged from 50 to 95% and 37 to 92%, respectively, for nine of the 10 facilities. The smallest facility removed 85% of the suspended solids and 37% of the phosphorus. The authors were unable to relate the variability of performance to any factor of design or operation. Constructed wetlands performed somewhat better than natural wetlands. The only conclusion that might be safely drawn from this study is that a surface area greater than about 1 or 2% of the tributary watershed is not justified, given the uncertainty of any improvement in performance with the increase in size. Lacking, however, are data on the percentage of each watershed that is impervi- ous. The facility can be sized using the same procedure outlined for Wet Ponds, TC2. However, inasmuch as a wetland is shallower than a wet pond, sizing the wetland for the same VbfVr as a wet pond requires considerably more surface area. Given the likely advantages of a constructed wetland over a wet pond, some may consider this to be an unreasonable Penalty-' It is therefore recommended that surface area of the constructed wetland not exceed that which would be determined for a wet pond. Additional design considerations include: • Have 25% to 50% (forebay and afterbay) 3 to 6 feet deep, and remaining area 6 in. to 24 in. deep or as appropriate for the wetland species selected. This geometry should provide satisfactory conditions for wetland wildlife (Adams et al.,1983). • Side slopes of at least 4:1 to a water depth of 2 feet except on very small facilities where retaining walls may be used to conserve space. If retaining walls are used, the area must be fenced for safety. • Access for maintenance vehicles to the forebay, the outlet, and around the perimeter. TC3 Industrial Handbook 5 - 30 March, 1993 i Additional Information — constructed wetlands • Freeboard of at least 1 foot. • With earthen contained facilities, install an antiseep collar on the outlet pipe. • The soils must be suitable for wetland vegetation. If necessary organic soils (18 to 24 in.) must be imported to the site. • The soil must have an of mity for phosphorus. Soils with aluminum and iron are best. Soils saturated with phos- • phorus or a metal specie may cause the concentrations of these contaminants to increase in the overlying water. Minimize short-circuiting by placing energy dissipators at the inlet, and by having a high length to width ratio. Short circuiting must be minimized by using a generally rectangular configuration with a length to width ratio of a least 3:1 and by placing the inlet and outlet at opposite ends. The inlet and outlet can be placed at the same end if baffling (islands) is installed to direct the water to the opposite end before returning to the outlet. if topography or aesthetics requires the wetland to have an irregular shape, the pond area and volume should be increased to compensate for the dead spaces. Energy dissipators and entrance baffles will spread the water laterally across the facility. • Minimize water loss by infiltration through the wetland bottom. • Supplemental water may be needed to avoid loss of rooted vegetation during the dry period. To maintain the wet pool to the maximum extent possible excessive louses by infiltration through the bottom must be avoided. Depending on the soils, this can be accomplished by compaction. incorporating clay into the soil, or an artificial liner. Wetland vegetation species have evolved to handle the stress of seasonal variations in water availability. However, during the dry season there must be sufficient water to avoid complete desiccation of plant roots. Conse- quently. constructed wetlands are infeasible in areas where there is a lack of either a baseflow or near -surface ground water during the dry season: Supplemental water such as pumped ground water and treated process wastewater may have to be used. A wetland ecologist should prepare the planting design and specifications, and oversee the planting. Constructed wetlands may not need antivanex and trash rack devices on their outlets like a wet pond because of the rooted vegetation. See TC2, Wet Ponds regarding inlet design. Design concepts for outlet devices are discussed in TC5 Extended Detention Ponds. See Josselyn (1982) regarding wetland plant considerations: Establishing wetland vegeta- tion initially may be difficult and require multiple plantings. Nlaiuz�laussi • Check at least annually and after each extreme storm event • Remove accumulated foreign debris. • Repair areas of sloe erosion. • Employ mosquito countermeasures as required by local authorities. • Clean deposits from the forebay when a loss of capacity is significant, probably every 3 to S years depending on the land use (see TC2, Wet Ponds), or when the concentrations of toxicants in the sediments are reaching a level of concern. There is some question as to whether annual harvesting of rooted vegetation is either practical or effective at reducing seasonal losses of nutrients and prolonging the life of the facility (USEPA,' 1988). The benefits of harvesting may depend upon the wetland specie (Suzuki, T. et al., 1991). Placing rooted vegetation in gravel beds rather than soil may make harvesting practical. If harvesting is to be done, it should occur twice per season, in the early summer when nutrient content in the plant material is at its peak, and in the fall before plant dormancy. Given the significant role of the bottom soil in removing metals and phosphorus its replacement may be required, although, probably not more frequently than once every few decades. Cleaning the forebay more frequently is important as noted above. r TC3 Indimtrial TTo..4v— t. a - 31 March,1993 Additional Information - constructed wetlands Another consideration is the regulatory implications of removing accumulated material from constructed wetlands. Do such actions require a 404 or other permit? At present, constructed wetlands are excluded from this requirement (Ritchie,1992). REFERENCES Adams, L.., Dove L.E. D.L. Leedy, and T. Franklin., 1983, "Urban Wetlands for Stormwater Control and Wildlife Enhancement- Analysis and Evaluation", Urban Wildlife Research Center, Columbia, Maryland. Faullmer, S. and C. Richardson, 1991. "physical and Chemical Characteristics of Freshwater Wetland Soils", in CgjL- saucted Wed for W ttrwa ear Treatment ed. D. Hammer, Lewis publishers, 831 pp. Guntenspergen, G.R., F. Steams, and JA Kadlec, 1991, "Wetland Vegetation", in Constructed Wetlands for Wastewater Treatment, ed. D,A- Hammer, Lewis Publishers, 831 pp. Josselyn, M.,198Z "Wetland Restoration and Enhancement in Califomia", Institute of Marine Resources, University of California. Ku lzM L,1990, 'Water Pollution Control Aspects of Aquatic Plants", Municipality of Metropolitan Seattle. Livingstone, E., pers. comm.. Florida Department of Environmental Conservation. Meiorin, E.C" 1991, Urban Runoff Treatment in a FreshBradrish Water Marsh in Fremont, California", in Constructed Wetlands for Wastewater Treatment, Ed. D. A. Hammer, Lewis Publishers. Metropolitan Washington Council of Governments (MWCOG), March, 199Z "A Current Assessment of Urban Best Management Practices: Techniques for Reducing Nonpoint Source Pollution in the Coastal Zone". Reddy, K, and W. Smith,1987, Aquatic Plants for Water Treatment and Resource Recovery, Magnolia Press. Ritchie, S,199Z letter to R.B. James, Chairman of the Management Committee of the Santa Clara Valley Nonpoint Source Pollution Control Program. Silverman, G, 198Z "Wetlands for Oil and Grease Control", Tech Memo. 87, Association of Bay Area Governments. Suz'K T., W.G.A. N-Wanka, and Y. Kurihara, 1991, "Amplification of Total Dry Matter, Nitrogen and Phosphorus Removal from Stands of phragmites australis by Harvesting", in Constructed Wetlands for Wastewater Treatment, Ed. D. A. Hammer, Lewis publishers. Strecker, E.W., J.M. Kersnar, and E.D. Driscoll, 1992, "The Use of Wetlands for Controlling Stormwater Pollution"for USEPA Region V. , Thut, R.. 1988, "Utilization of Artificial Marshes for Treatment of Pulp Mill Effluents", in Constructed Wetlands for Wastewater Treatment, Ed D. Hammer, Lewis Publishers. 11' United States Environmental prot6ction Agency (USEPA), 1988, "Constructed Wetlands and Aquatic Plant Systems for Municipal Wastewater Treatment", EPA 625/1-88-M 1 TO 1 Industrial Handbook 5 32 March, 1993 0 u BMP: B10FiLTERs considerations sa;�s ti CHECK CAN FLOW At ."►" ,,� Water Availability Aesthetics Hydraulic Head cnAss "` Environmental Side Effects DESCRIPTION Biofilters are of two types: Swale and strip. A Swale is a vegetated channel that treats Targeted Constituents concentrated flow. A strip treats sheet flow and is placed parallel to the contributing Sediment Surface. Q Nutrients EXPERIENCE IN CALIFORNIA Q Heavy Metals No biofilters specifically designed to treat storm water have been located. However, instances of "biofilter by happenstance" exist in northern communities (Davis, Sacramento, Toxic Materials Tmiock, Fresno) where storm water is discharged to a grassed area prior to an inlet or an Q Floatable Materials infiltration area. 0 Oxygen Demand - SELECTION CRITERIA ing Substances • Comparable Performance to wet ponds and constructed wetlands. Q Oil &Grease • Limited to treating a few acres. • Availability of water during dry season. 0 Bacteria & Yrruses LIMITATIONS a rev Ham • Poor performance has occurred but this appears to be due to poor design. �tTcant Impact • 0 Probable Low or May be limited to areas where Summer irrigation is feasible. unknown Impact • Can be difficult to maintain sheet flow in strips. • Can be difficult to avoid channerbation in swales. Implementation • Cannot be placed on steep slope. Requirements Area required may make infeasible on industrial sites. • Proper maintenance required to maintain health and density of vegetation. 0 capital casts DESIGN AND SIZING CONSIDERATIONS O&M costs 0 • The surface area is defined by Figure 4A Maintenance • The minimum width for a Swale is determined b Mannin s 0 Training Minimum length of a strip is 10 feet. y g Equation. The longitudinal slope must not exceed 5%. • Use a flow spreader and energy dissipater at the entrance of a Swale. • Good soils are important to achieve good vegetation cover. High O Low CONSTRUCTIONANSPECTION CONSIDERATIONS TC4 • Make sure soils are suitable for healthy vegetation. Level cross-section and even longitudinal slope for swales. • Achieve sheet flow with strips. Best Managemen Practices z-33 March, 1993 Additional Information— Blofiiters A biofilter Swale is a vegetated channel that looks similar to, but is wider than, a ditch that is sized only to transport flow. The biofilter Swale must be wider to maintain low flow velocities and to keep the depth of the water below the height of the vegetation up to a particular design event. A filter strip is placed along the edge of the pavement (its full length if possible). The pavement grade must be such as to achieve sheet flow to the maximum extent practical along the strip. Vegetated biofilters will likely see limited application in industrial settings. Strips are most suitable for parking lots which under this general permit do not require consideration unless they drain to a drainage system that also receives flows from the industrial activities of concern. Within the industrial site itself conditions are usually net suitable for locating a grassy area next to a paved area. Typically, the industrial area is paved to the property fine. If the store water passes through a ditch prior to leaving the site it may be possible to widen the ditch into a Swale. The performance of biofaters is probably somewhat less than wet ponds and constructed wetlands because the latter Provide treatment both during and between storms. Some researchers have observed poor performance, recommending their use only in combination with other treatment control BMPS. However, most field research on Swale performance has been conducted on gassed roadside ditches. A Swale must be wider than a traditional roadside ditch, to avoid excessive flow velocities which topples the grass and causes c an elization. The Swale bottom must be as level as possible; energy dissipation and a flow spreader should be placed at the entrance to minimize channelization. The pavement must be as level as possible along its boundary with a biofilter strip. The Pavement edge should be left clear, that is, no curbs. Parking stall blocks must be open to pass the flow as unhindered as possible. Use of curb arts in curbs is not a satisfactory approach. The cuts charnelize the water and can clog with debris. The performance of strips may be compromised by the failure to achieve sheet flow at the interface between the paved area and the strip. Turf grass is the preferred vegetation. Figure 4B shows recommendations for seven species of turf grass and one ground cover plant for various areas of California (Youngner, et al, 1962). More recent information in this regard is also shown in Figure 4C (CCAE,.1984). Turf grass will require summer irrigation to remain active. Although it has not been tried it may be possible to allow the grass to become dormant during the summer since the biofilter is only in service during the wet season. The biofilter could be irrigated beginning in Ocmber to bring it to a healthy condition prior to the first storms. Ground cover species suitable for a non -irrigation situation may work but, it also has not been tried. The Soil must be of a fertility and porosity that allows for healthy vegetation. A porous soil also promotes infiltration. See the references that follow for Agricultural Extensive publications on efficient water use by turf Brasses - If erosion of the swale is of concern because of the difficulty of maintaining a good grass cover, consider the use of concrete grids (see Infiltration Systems) or similar material. Another concept is to use check dams to divide the Swale into a series of terraces, reducing the longitudinal slope to perhaps 1%, thereby reducing flow velocities. Design Several methods have been proposed to size biofilters (Horner, 198S, FHWA, 1989; IEP, 1991. Tollner, et al.. 19.76). However, information on the relationship between biofilter area and performance is lacking for urban conditions. Figure 4A .uses the method of Horner (1988) with the 2-year storm as the design event, a slope of 3%, and a grass height of 4 inches. A biofilter is sized to treat all storms up to a particular design event The design event can be relatively small because the aggregate of all small events represents the majority of pollutant runoff. Research in western Washington (Metro, 1992) found that a biof iter sized according to this technique removed 80 percent of the suspended solids and attached pollutants and.50% of the soluble zinc. It was not able to remove dissolved phosphorus or copper. TC4 Industrial Handbook 5 - 34 March, 1993 Additional Information Bioftfters Figure 4A is meant for guidance only and should be used with caution in areas where precipitation varies greatly because of terrain. The design engineer must determine the width of a Swale using Manning's Equation and the 2-year rainfall intensity (California, 1976) appropriate to the site. An "n" of 0.20 is recommended (Metro, 1992). The design engineer must also calculate the peak flow of the 100-year event to determine the depth of a Swale. Since a width using an "n" of 020 is generally wider than what is required of a grass lined channel, channel stability should not be of concern. It is generally not necessary to have a bypass for the extreme events because the minimum width specification combined with the relatively gentle slope avoids excessive velocities. If erosion at extreme events is of concern, consider the above Concepts to minimize erosion. The design engineer can make the Swale wider than determined in the above step, with a corresponding shortening of the Swale length to obtain the same surface area. However, there is a practical limitation on how wide the Swale can be and still be able to spread the flow across the Swale width. Splitting the flow into multiple inlets and/or placing a flow Spreader new the storm inlet should be incorporated into the design. A concept that may work is to place a level 2"x 12" timber across the width of the Swale perhaps 10 feet from the pipe outlet Place gravel between the outlet and the timber, to within 2 inches or so of the top of the timber. Place large rock immediately near the outlet to dissipate the flow energy; the rock also may help distribute the flow. The timber will function like a weir. Flow spreaders have seen limited application and their effect on performance has not been evaluated. The problem of spreading the flow across the width of the Swale may limit its use to tributary catchments of only a few acres. The minimum width based on using Manning's Equation results in widths of 3 to 12 feet per acre of impervious tributary surface, depending on the location and longitudinal slope. A minimum length of 10 feet is recommended for biofilter strips. Length here is defined as the measurement in the direction of flow from the adjoining pavement Lengths of 20 to 50 feet have been recommended by most practitioners perhaps because of the Concern that sheet flow cannot be maintained. Wherever room permits a length greater than 10 feet should be used. The short length is recommended in this handbook because space is at a premium at most existing. industrial sites: 10 feet should work satisfactory if good sheet flow is maintained and no obstructions such as curbs are placed along the pavement edge. The type of strip discussed here is not to be confused with the natural vegetated buffer strip used in residential develop. meats to separate the housing from a stream or wetland. As the later type follows the natural contour flow cihannelhation is more likely and lengths of 75 to 150 feet are recommended. The length of pavement prior to the strip should not exceed a few hundred feet to avoid channelization of large aggre- gates of runoff along the pavement before it reaches the pavement edge. To avoid channelization, care must be taken ding construction to make sure that the cross-section of the biofilter is level and that its longitudinal slope is even. Channelization will reduce the effective area of the biofilter used for treatment and may erode the grass because of excessive velocities. L[ailltena� The facility Should be checked annually for signs of erosion, vegetation loss, and channelization of the flow. The grass should be mowed when it reaches a height of 6 inches. Allowing the grass to grow taller may cause it to thin and become less effective. The clippings should be removed 1 TC4 1 Industrial Handbook 5 - 35 March, 1993 Additional Information eiorinem California (State of), 1976, "Rainfall Analysis for Drainage Design, Volume 3, Intensity -Duration -Frequency Curves", Bulletin No.195, Department of Water Resources. California Cooperative Agricultural Extension (CCAE), 1984, "Selecting the Best Turf Grass", Leaflet 2589. CCAE, 1985, "Turfgrass Water Conservation", Bulletin 21405. CCAE, 1991, "Effluent Water for Turfgrass Irrigation", Bulletin 21500 Federal Highway Administration (FHWA), 1989, "Retention, Detention, and Overland Flow for Pollutant Removal of Highway Stormwater Runoff (Draft)", Report No. FHWA/RD-89203. Haver, RR.,1988, "Biofiltration Systems for Storm Runoff Water Quality Control", Washington State Department of Ecology. IEP,1991, "Vegetated Buffer Strip Designation Method Guidance Manual", Narragansett Bay Project Lager, J.A., W.G. Smith, and G. Tchobanoglous,1977, "Catchbasin Technology Overview and Assessment", USEPA 6002-77-051. Metropolitan Washington Council of Governments (MWCOG), March, 199Z "A Current Assessment of Urban Best Management Practices: Techniques for Reducing Nonpoint Source Pollution in the Coastal Zone". Municipality of Metropolitan Seattle, (Metro),1992, "Pollutant Removal Effectiveness of a Designed Grassy Swale in Mountlake Terrace, Washington (Draft)". Sacramento Catty Cooperative Agricultural Extension, "Water Efficient Landscape Plants" by Pamela S. Bone, Environmental Horticultural Notes. Tollner, E.W., and BJ. Barfield, 1976. "Suspended Sediment Filtration Capacity of Simulated Vegetation", Trams. American Society of Agricultural Engineers, 19, 678. Youngner, VB..I.H. Madison, M.H. Kimball, and W.B. Davis, 196Z "Climatic Zones for Turfgrass in California", California Agriculture, 16 (7), 2. TC4 a«� Industrial Handbook 5.36 . March, 1993 Additional Information - Biof ws FIGURE 4A. SIZING GUIDELINE FOR BIOFIL.TERS TC4 (SQ. FTJIWERVIOUS ACRE) Industrial Handbook 5.37 March, 1993 Additional Information— Biofiiters Weil adapted to area i Adaptable with signer main[enanr_ k4 Better adapted grass available j ! Not adaptable FIGURE 4B. STATE OF CALIFORNIA SHOWING TC4 MOST SUITABLE TURF GRASS SPECIES industrial Handbook 5.38 March, 1993 Additional information — Bwows COLD TOLERANCE {winter color persistaace) HEAT TOLERANCE High .Creeping tent grass Kentucky owe -grass Red fescue Cofcnial centgrass Higniand bentgrass Perennial r;egrass 'all fescue Weeping aikatigrass Oichcndr a Zoysiagrass C.ommcn bermudagrass Hybrid bermudagrass Kikuyugrass Seashore oaspatum Low St. Augustinegrass MOWING HEIGHT ADAPTATION High cut Tall fescue Red fescue Kentucky bluegrass Perennial rregrass Weeping alkafigrass SL Augustinegrass Common bermudagrass Oichondra Kikuyugrass Colonial bentgrass Highland bentgrass Zoysiagrass Seashore pasRalum Hybrid bermudagrass Low Cut Creeping bentgrass sign =ovsiagrass ► -•.zrc zermucagrass ze..jaacrsss :easncre :)asoai-:r- ' �.. Au,,usttnecrasi '::kuvugrass 3ti 4eSC::e tc:,yncra ^enr,rass 4entucxv awegrass - ignianc !)entgrass �erenria► rr--grass .-alonial oentgrass °weeoing aikaligrass Low Red fescue DROUGHT TOLERANCE High Low Hybrid bermudagrass Zoysiagrass Common bermudagrass Seashore paspaium St. Augustinegrass Kikuyugrass Tall fescue Red fescue Kentucky bluegrass Perennial ryegrass; Highland bentgrass Creeping bentgrass Colonial bentgrass Weeping alkaligrass Dichondra MAINTENANCE COST AND EFFORT High Creeping bentgrass oichondra Hybrid bermudagrass Kentucky bluegrass Colonial bentgrass Seashore paspafum Perennial ryegrass St. Augustinegrass Highland bentgrass Zoysiagrass Tall fescue Common bermudagrass Low Kikuyugrass TC4 FIGURE 4C: ADDITIONAL INFORMATION ON THE SUITABILITY OF TURF GRASS SPECIES Industrial Handbook 5 - 39 March, 1993 0 0 BMP: EXTENDED DETENTION BASINS F igh*=r .z V\ --Trcc�751xt Extended detention basins are dry between storms. During a storm the basin fills. A bot outlet releases the storm water slowly to provide time for sediments to settle. EXPERIENCE IN CALIFORNIA There are no known basins in California, Hydraulic detention basins may function like extended detention basins if the former has been sized to control the pre -development 2- year event. More liberal standards do not provide sufficient detention time. SELECTION CRITERIA • Objective is to remove only particulate pollutants. • Use where lack of water prevents the use of wet ponds, wetlands or biofilters. • Use where wet ponds or wetlands would cause unacceptable mosquito conditions. LEWrATIoNS • May be less reliable than other Wmanent control BMPs. • Inability to vegetate banks and bottom may result in erosion and resuspension. • Limitation of the orifice diameter may preclude use in small watersheds. • Requires differential elevation between inlet and outlet • Pending their volume and depth basin designs may require approval from State Division of Safety of Dams. DESIGN AND SIZING CONSIDERATIONS • Basin volume is sized to capture a particular fraction of the runoff. • Drawdown time of 24 to 40 hours. • Shallow basin with large surface area volume, performs better than deep basin with same • Place energy dissipators at the entrance tommimize bottom erosion and resuspension. • Vegetate side slopes and bottom to the maximum extent practical. • If side erosion is particularly severe, consider paving or soil stabilization. • If floatables are a problem, protect outlet with trash rack or other device. • Provide bypass or Pass through capabilities for 100 year storm. CONSTRUCTIONANSPECTION CONSIDERATIONS • Make sure the outlet is installed as designed. Industrial Handbook 5 - 40 Considerations Soils rea Required Slope Water Availability Aesthetics H drau/ic Head Environmental Side Effects Targeted Constituents Sediment Q /Nutrients Q Heavy Metals Q Toxic Materials Q F/oatab/e Materials Q Oxygen Demand- ing Substances Q OU A Grease 0 Bacteria & Viruses Uke* to H,ws Sim Ikant Impact O probable Low or Unknown impact Implementation Requirements Capital Costs Q O&M Costs Q Maintenance O Training 1 0 High O Low TC5 Best Managemen Practices March, 1993 --•.... ""n WjL""Uwwc 5.41 March, 1993 Additional Information— Extended Detention Basins Extended detention ponds and vaults may be particularly appropriate to California where dry weather base flow cannot be used to maintain water levels, as is required for wet and constructed wetlands. These systems are suitable for essentially any size tributary area from an individual commercial development to a are less expensive to construct, brit un °p'm large residential area.. Surface ponds concretee retain derground vaults may be app�riate in commercial developments. Use of g walls will reduce the space required by a pond. The basic elements of an extended detention basin are illustrated in Figure 5A. The configuration shown in Figure 5A is most appropriate for large sites. Extended detention provides a lower removal efficiency than wet ponds and constructed wetlands: the facilities are smaller thereby reducing their effectiveness with particulate pollutants, and they do not have the abilityto remove dissolved contaminants. Also, extended detention facilities may be less reliable than constructed wetlands or wet ponds because of the lack of a permanent water pool (See Figure 5A). But if desired, a shallow included in the design but this is more of an aesthetic consideration. If irripQOI of 1 to 3 feet could be the bottom of the facili may water is available, a thick grass turf on ty y provide some removal of dissolved contaminants, like a vegetated biofilter. See TC4 Biofikers for recommendations on turf grass and groundcover species. Where irrigation water is not available, there may be concerns about erosion and resuspension of particulate pollutants in surface ponds- This, however, has not been a significant problem in Austin, Texas where sand filters are preceded b dry settling ponds (Hartigan, pers. comm.). However, the designmust ' Y Potential for this � several features to minimize the Problem. Drought tolerant vegetation may work but has not been evaluated. Nonvegetative materials may help such as concrete or Plastic grids, small riprap, erosion matting, or paving. A paved forebay may facilitate maintenance thereby reducing the material available for resuspension. The recommended dmwdown time of 24 to 40 bouts for a full pond is based on extended detention ponds have been monitored and generally hauled laboratory data. A few drawdown time of about 24 hours. Y provide a removal efficiency of 60 to 8096 with a nia sediment that Forty hours t recommended in order to settle out the finer clay particles in Califor- typcally adsorb toxic pollutants. DoiE>1 Determine the volume of the basin using the appropriate figure from Appendix D. The select the appropriate figure for your area; (2) determine for the catchment the procedure is as follows: (i) connected to the storm drain Percentage of impervious area directly system: (3) choose a capture basin; and (4) multiply this unit goal, and read the required unit volume required for the volume linos the total acreage of the catchment and convert to cubic feet. This volume is also referred to as water quality capture volume shown in Figure 5A. Total impervious acres may be used in lieu of y connected impervious acres if it is easier to determine the former although result in a Although these variations are not equivalent, the are this will facility' Pad basin performancx. Y reasonable given the uncertainty of the methodology and ex - What should be the capture gam? To achieve an equivalent pollutant capture percentage as a wet pond, 85 to 95 Percent of the runoff must be captured and detained, But capture volumes over 85 percent are not cost effective as the determining cases a Appendix a show. Therefore it is recommended that a capaire volume of 85 percent be used for capturdetermmrng the detention basin size required, Because of the possibility of resuspension of materials during extreme storms consideration should be given to placing the basin off line, that is, it should have a bypass for the extreme events. Bypassing larger events will also allow the bedload carried by the storm and is necessary for beach replenish- ment to move downstream. A drawdown time of 40 hours is recommended in order to settle out the finer clay ve; however, 24 hours can be used if it can be demonstrated that this rate will remove 80% of the solids. The anatcles as stated � of n nctff ovei 1 TC5 Industrial Handbook 5 - 42 �.�..�. March, 1993 Additional Information — Extencw Detention Basins the hydrologic model STORM and California precipitation data found that increasing the drawdown time from 24 to 40 hours increased the size of the basin by only about 10% to 20% depending on the location (see Appendix D). Proper hydraulic design of the outlet is critical to achieving good performance of the detention basin. The two most common outlet problems that occur are: 1) the capacity of the outlet is too great resulting in partial filling of the basin and less than designed for drawdown time and 2) the outlet clogs because it is not adequately protected against trash and debris. To avoid these problems, two alternative outlet types are recommended for use: 1) V-notch Wier, and 2) perfo- rated riser. The V-notch wier will not clog, but it is also difficult to maintain small release rates at low heads. The Perforated riser if properly designed and gravel packed gives much better control and is recommended over the V-notch Wier. Two different approaches can be used to control the outflow. One is to use a single orifice outlet with or without the protection of a riser pipe. The other is to use the perforated riser itself for discharge control. Both approaches are presented below. Flow Control Using a Single Orifice The outlet control orifice should be sized using the following equation (GKY, 1989). a — 2A(H-Ho)0.5 _ (7x 10-5)A(H-Ho)0.5 36000T(2g)0_5 CT (1) where: a = area of orifice (ft2) A = average surface area of the pond (ft2) c = orifice -coefficient T = drawdown time of full pond (his.) g = gravity (32.2 ftJsec2) H = elevation when the pond is full (ft) Ho = final elevation when pond is empty (h) With a drawdown time of 40 hours the equation becomes: a = (1.75X10-6)A(H-Ho)0.5 C (2) Assuming an average release race at one half the pond depth, a common approach in several design manuals, leads to considerable error. If the pond has a significant variation of surface area with depth, do not use Equation (2); consult GKY (1989). Care must be taken in the selection of "c": 0.60 is most often recommended and used. However, based on actual tests GKY (1989) recommends the following: c = 0.66 for thin materials, that is, the thickness is equal to or less than orifice diameter c = 0.80 when the material is thicker than the orifice diameter Drilling the orifice into an outlet structure that is made of concrete can result in considerable impact on the coefficient, as does the beveling of the edge. The experiments by GKY (1989) were with sharp edged orifices. I TC5 Industrial Handbook 5 - 43 . March,1993 Additional Information— Extended Detention Basins Equation (1) defines the orificearea where a single orifice outlet is used to regulate the detention basin outflow. How- ever, a recent survey of extended detention facilities (Galli, pers. comm.) found the drawdown time of small storms that do not fill the facility to be too short to provide effective treatment. The facilities surveyed were designed for a draw - down time of 24 hours. A 40 hour drawdown may provide sufficient time for the smaller storms. But it may be prudent to take additional steps to be certain that the small storms, which represent the majority of pollution, are effectively treated. One approach would be to check the design analysis to determine if the facility takes at least 24 hours to drain when half full. If not, either modify the design to achieve this objective, or install a two orifice outlet. The lower outlet is sized to drain a half -full facility in 24 hours. The second orifice is placed at the mid -water elevation and is sized in combination with the lower orifice to drain the entire facility in 40 hours. Another approach is to install the outlet about one foot above the bottom of the pond (essentially enlarging the micropool area). This lower area will dry up between storms and will capture much of the volume of small storms and improving pollutant removal. Three alternative outlet structures are suggested (Figure 5B). The concrete block structure is appropriate for large ponds. The riser pipe is suggested for small to large ponds. Placing the outlet control in the berm or in a manhole located downstream of the facility is most suitable for small ponds. Recommendations regarding the design of a riser pipe are shown in Table 5A for Austin (1988). Table 5A provides guidance on the location of holes. To prevent clogging of this orifice and the bottom orifices of the riser pipe, wrap the bottom three rows of orifices with geotextile fabric and a cone of one to three inch rock. The holes in the riser pipe Should not be modified to achieve a 40 hour drawdown time. Rather, the control orifice should ,laced doa a=m. For small facilities, place the control orifice in a manhole between the pond and the filter as shown in Figure 5B. Use a "T-pipe" (Figure 5B) to submerge the orifice. TABLE 5A PERFORATED OUTLET RISER PIPE ORIFICES (Austin, 1988) VERTICAL SPACING RISER PIPE BETWEEN ROWS NUMBER OF PERFORATION DIAMETER (center to center) PERFORMATIONS DIAMETER 6 in. 8 in. 2.5 in.' 9 per row 1 in. 10 in, 2.5 in. 2.5 in. 12 1 in. 16 1 in. Clogging Of the bottom holes has been observed in riser pipes in the mid -Atlantic states (MWCOG, 1992) suggesting that the diameter of the riser holes should not be less than 3/4 to I' (MWCOG, 1992) although a minimum diameter of 2" is I being considered (Galli, pers comm.). However, most of the facilities surveyed had risers without the gravel coop and the outlet holes were modified to provide drawdown control. Modifying the holes in the riser to control the outlet rate reduces the diameter of the holes and increases the risk of clogging. However, gravel packing the riser pipe as shown in Figure 5B2 and 5C.1 will minimize this risk Submerging the control orifice as shown in Figure 5133 will allow the use of a smaller orifice diameter. One orifice with a diameter of in inch, or 1 inch to be conservative, allows the use of extended detention for very small catchments. Detention facilities in western Washington .use this concept and have not experienced clogging problems. Flow Control I Tsine the Perforated i p* For outlet control using the perforated riser as the outflow control, it is recommended that the procedure developed by the Denver Urban Drainage and Flood Control District be used (UDFCD, 1992) as illustrated in Figures 5C and 5D. Figure 5D uses a valve for C, of 0.65. This design incorporates flow control for the small storms in the perforated riser but also, provides an overflow outlet for large storms. if properly designed, the facility can be used for both water juality and TC5 March, 1993 Additional Information— Extended Detention Basins drainage control by: 1) sizing the perforated riser as indicated for water quality control; 2) sizing the outlet pipe to control peak outflow rate from the 2 year storm; and 3) using a spillway in the pond berm to control the discharge from larger storms up to the 100 year storm. • Do not locate on fill sites or on or near steep slopes if is expected that much of the water will exit through the bontom, or modify the bottom to prevent excessive infiltration. Energy dissipation at the inlet to minimize erosion • Vegetate the slopes and bottom for the same reason • Freeboard of i foot • Side slopes of at least 2:1 unless vertical retaining walls are used • Incorporate bypass or overflow for large events • Provide dedicated access to the basin bottom (minimum 4:1) for maintenance vehicles • With a riser structure, include an anti -vortex device and a debris barrier. xhnct inspections semiannually and after each significant storm. Remove floatables and correct erosion problems in Pond slopes and bottom. Pay particular attention to the outlet control orifice(s) for signs of clogging. If the orifice is need in a Type 2 catch basin, remove sediments if they are within 18 in. of the orifice plate. Often extended detention in serve multiple used, e.g. baseball field, resulting in higher maintenance costs. Austin (City of).1988, "Environmental Criteria Manual^. J- pers. Comm" Metropolitan Washington Council of Governments. GKY,1989. "Outlet Hydraulics of Extended Detention Facilities , for the Northern Virginia Planning District Commis- sion. P. Pers. comm., Washington Department of Ecology (formerly with the City of Austin). Washington Council of Governments (MWCOG), March, 199Z "A Current Assessment of Urban Best Practices: Techniques for Reducing Nonpoint Source Pollution in the Coastal Zone". Metropolitan Washington Council of Governments (MWCOG),1983, "Nationwide Urban Runoff Program Pollution Removal Capability of Urban Best Management Practices in the Washington Metropolitan Area , available from NTTS, PB84-245497. Virginia Planning District Commission (14VPDC), 1987, "BMP Handbook for the Occoquan Watershed- . Randall, C.W., et al, 198Z "Urban Runoff Pollutant Removal by Sedimentation^, in Proceedings of the Conference on Stormwater Detention Facilities, Henniker, NH, ASCE, pp 205-209. Urban Drainage & Flood Control District, Denver Colorado, "Urban Storm Drainage Criteria Manual - Volume 3 - Best Management Practices - Stormwater Quality", September, 1992. Whipple, W. and J. Hunter, 1981, "Seakability of Urban Runoff Pollution", J. Water Pollution Control Federation, 53 (12): 1726-1731. 1 TC5 1 Industrial Handbook 5 - 45 March, Additional �Informafion— ExtDeterwon Ewins N 3 LL .4 0 o� U D LIO C y = C n G N PMR ZE � Y y y � _ y C z E CL 1° CL cj m m •r'•i, m to tit Z CLNow Industrial Handbook 5-46 m 3 at 1 us.G C Coto March, 1993 Addiiid%l Information — ��a Deterwon Baisins FIGURE 58. i CONCRETE STRUCTURE mergency Spillway - `- - 10 or 25 Year Outlet (It Applicable) Flood Control Outlets 2 Year Outlet - i :aaended � a Detention Outlet ' Side View From View FIGURE 532 RISER •PIPE hi ,a Q= Design into Impoundment as Flood Control Spillway (Used By Permissi on, UDFCO, 1992) F 'a Envelope Grave! E?ti Control ' . Orifice Plate (recommended) L % Cua.c �e (See Table SA) T FIGURE 58.3 CONTROL MANHOLE Contrd Structure ` Flood Control Outlet Emergency Overflow W.S. 1 Pond Design W.S. - r,,_. Source: Douglas County, Colorado 1 Senn E_ mbanan kmeru u Debris Barrier I Orulce Place TC5 FIGURE 5B. OUTLET CONFIGURATIONS USING SINGLE ORIFICE FOR FLOW CONTROL Industrial Handbook 5 - 47 March,1"3 Additional Information =- aderxw Ddew= ewsim Threaded Cap te 1 Water Ouality Atxess Outlet Pins --.. Riser Pipe (See Oetaa) (Min. 3 R) Notes: 1. The owlet aloe shall be sized to control overflow, into 7. 4�3i : s' ,4;. ; t. , •,.• ; . .•: ar K:�:: 2. Attemate d*s5ni ckide nCete riser. 'Y.. ;Jr;{ ..:'�.;q: sit{�;:� ;a'' • :; Hydrobrake owlet {or onficea �g aborort. Size Base to Prevent OUTLET WORKS Hydrostatic Uplift NOTTO SCALE Not": I. number of odes . 8 2.11.6ni num hole diameter . mr da. TF'j*Ml*r of Fertorated Columns Hole Oiame ON 114* Ur Ur i-la* diamearAir Rows O Vent in Threaded Cap 6 12 ' 12 9 — 41 Water Owbty a t6 t6 t2 Outlet Holes a 41 O O O 10 20 , 20 to to Ductile Iron or 12 24 ' 24 1 t8 t2 4 • Q St" Pipe Hole Oiameter Area of Ho4 rn.) (in,2 ) its1/4 C 013 ° WATER OUALITY 318 OA49 RISER PIPE 112 o.tto . era 0.196 N O S 3/4 0.307 718 o.sa2 (Used By Permission, UDFCD. 1992) 1 0.6m O.M FIGURE 5C. OUTLET CONFIGURATION USING TC5 PERFORATED RISER FOR FLOW CONTROL rraeee..t lndmstrial Handbook 5 48 March, 1"3 Industrial Handbook 5 - 49 March, 1993 B M P: MEDIA FILTRATION E DESCRIPTION Consists of a sealing basin followed by a filter. The most common filter media is sand; some use peathand mixture. EXPERIENCE IN CALIFORNIA • A tenant at the Port of Long Beach recently installed a sand filter_ The City of Los Angeles will soon install several experimental filters. SELECTION CRrMRIA • Objective is 10 remove only sediment (particulate pollutants). • Use where unavailability of water prevents the use of wet ponds, wetlands, or biofiIters. • Can be placed underground. • Suitable for individual developments and small tribe tary arras up to about 100 acres. May require less space than other treatment control BMPs. LIMITATIONS • Filter may require more Bead loss. fregrtent maim than most of the other BMPs. Dissolved pollutants are. not captured by sand. • Severe clogging potential if exposed soil surfaces exist upstream. DESIGN AND SIZING CONSIDERATIONS • Settling basin smaller than wet or extended detention basin. • spread flow across filter • Place filter onne to Protect fi+ma extreme events. • Miruntize erosion in settling basin. CONSTRUCTIONANSPECTION CONSIDERATIONS • Be certain filter sand is clean and the outlet device hOm the basin to the filter is level. MAINTENANCE REQUIREMENTS ' Clean filter surface about twice annually, or more often if watershed is excessively erosive. COST CONSIDERATIONS • Filtration system may use less space than other systems. • Smaller media improves performance but increases maintenance costs. Considerations SO& Area Required Slope Water Availability Aesthetics H draulic Head Environmental Side Effects Targeted Constituents Sediment 0 Nutrients Q Heavy Metals Q Toxic Materials Floatable Materials 0 Oxygen Demend. ing Substances Q Oil A Grease Q Bacteria & Viruses LIkety to Ham ftnifiesat knpeat O Pmbab4 tow or Unknown Impact implementation Requirements Capital Costs Q O&M Costs 0 Maintenance O Training High O Cow TC6 Best Inanstral Handbook s - so --........ _ March, 1993 Additional Information — Media Filtration Sand filters may be particularly suitable for industrial sites because the settling basin can be located mod. A sand filter consists of two units: settling basin and the filter. Pretreatment is essential to avoid rapid clogging of the filter. Peattsand mixture has been used: peat having the ability to remove dissolved contaminants. However, there have been clogging problems (Tomasak, et al, 1987) but this may be due to using the wrong type of peat (Galli, 1990). Limited research indicates that compost made from leaves is very effective at removing dissolved phosphorus and metals, and oil and grease (Stewart, 1989). A new concept is placement of a filter device in a catch basin insert (McPherson,1992) which may be very well suited for industrial sites. Field research in the City of Austin, Texas (Austin. 1990) indicates the sand filter has a removal efficiency of suspended solids that is similar to wet ponds and extended detention: 70 to 90%. The observed removal of metals was 20 to 80%. d%mg on the mew, 20 to 30% for nitrogen, and 50 to 60% for phosphorus. These rates are also similar to wet Ponds, which is not expected as a filter does not remove dissolved contaminants. Sand with a diameter smaller than used in Austin would likely improve performance but has not been tried Tbe'sand filter should be an ideal system for the Central Valley and Southern California It does not rely on vegetation, and has proven itself in the City of Austin. The sand filter is suitable for tributary areas of a less than an acre to about 50 acres. Make certain that any soil erosion problems in the site have been corrected (Chapter 4). Experience in Austin indicates that exposed soils during construction "upstream" from the filter can result in pentration of fines into the filter media, resulting in a need to replace the entire filter bed The system should have a bypass for extreme events. The most experience to date is with surface facilities shown conceptually Fi ure 6A. It can be used on catchments �P Y � m 8 , up to perhaps 50 acres. Its origin is Austin, Texas where there are now several hundred facihum The "Austin" filter uses an extended detention basin with a drawdown time of 24 hours. Two other systems are most suitable for small catchments of a few acres. An underground "linear" filter (Figure 6B) is used in Delaware (Shaver,1991). The filter accepts sheet flow from adjacent pavement. It, therefore, may ideal for industrial applications. Another underground design (Figure 6C) developed in Washington D.C. (Throng, 1989) is also ideal for developments. It accepts coneen- stated flow. Both of these underground systems use a wet vault (or water quality inlet, see TC) as the pretreatment devux. The fourth concept is (Figure 6D) is an insert placed in existing catch basins. It should only be used where umintenanm staff are available to check the filter frequently and where local flooding will not occur if the filter clogs. Determining the volume of h O=rment unit To size the pretreatment basin refer to the sizing methods for extended detention (TC5). With the sand filter the pre- treatment basin need not be as efficient as a full size system. The pretreatment system, however, should be large enough to provide a removal efficiency that avoids rapid clogging of the filter. As yet there is no clear answer on this question. For now it is suggested that the volume of a wet vault be such as to achieve a removal efficiency of 50 to 60%. The volume of an pretreatment unit can be decreased by reducing the drawdown time, which results in a lower but acceptable removal efficiency. The facility volume can be determined from TC5 Extended Detention using a drawdown time of ?A hours. I TC6 i Industrial Handbook 5 - 51 March, 1993 Additional Information — Media Flitawn Determining the surface -area f ti flier "Ile following equation is derived from Austin 1988 for a maximum full hours: ( ) ( pretnent basin) filtration time of 24 Filter area W) = 3630SuAH/K(D.H) (1) where: Su = unit storage (inches -acre) from Appendix D A — area in acres draining to facility H = depth (ft) of the sand filter D = average water depth (ft) over the filter taken to be one-half the difference between the top of the filter and the maximum water surface elevation K = filter coefficient recommended as 3.5 (Austin) Equation (1) is appropriate for the filter media size recomm The filter area must be ' ended by the City of Austin, diameter of 0.02 to 0.04 inches. increased if a smaller media is used (see Austin, Texas (1988)). Configuring a surface sand filter (City of Austin concept) Additional design criteria for the settling basin (Austin.1988)• • For the outlet use a perforated riser Pipe. as described in TCS, Extended Detention Size the outlet orifice for a 24 hour dmwdown • Energy dissipaw at the inlet to the settling basin • Trash rack at outlets to the filter Vegetate slopes to the extent possible (sea Vegetated Biofilters) Access ramp (4:1 or less) for maintenance vehicles • One foot of fi teeboard • Length to width ratio of at least 3-.1 and Preferably 5:1 Sediment trap at inlet to reduce resin. One conceptis shown in Figure 6E. Additional design criteria for the filter. • Use a flow qxtader (Figure 6A). • Use either of two alternative sand bed designs (Figure 6F). • Use clean sand 0.02 to 0.04 inch diameter. • Some have Placed geofabric on sand surface to facilitate maintenance. • Underdrains (Figure 6A). - Schedule 40 PVC. - 4 inch diameter. 3/8 inch perforations Placed around the pipe, - maximum 10 foot Pe. with 6 inch space between each perforation cluster. spacing between lateral& minimum grade of 1/8" per foot. Con�ri„g the linear filter Take the volume for the Pretreatment unit and the filter area identified above and cow shown in Figure 6B. gore into a structure similar to that g The structural design in Figure 6B assumes traffic loads over the filter. The structure can be less robust if it is located along the edge of the pavement, away from traffic. Other recommendations (Shaver, 1991): TC Industrial Handbook 5 - 52 March, 1993 0 Additional Information— Media fittration • Depth of sand 18" • Diameter of the outlet pipe should be 6" or less; use multiple outlets if necessary The filter must be positioned relative to the pavement in a manner that evenly distributes the flow as it enters the sedimentation chamber. Pavement design and construction is therefore critical. Configuring the wet va rit filter Similarly the volume of the wet vault and filter area are configured into a rectangular unit similar to that shown in Figure 6C. Other considerations for the wet vault include: • A length to width ratio of at least 3:1 to minimize short-circuiting • Baffles to mdt= entrance velocities and to retain floatables • Access ports to facilitate maintenance • Depth of the wet pool of at least 3 feet but not more than 10 feet Catch basin insert The etch basin insert filter may be ideal for industrial sites as it can be placed in existing catch basins, and therefore may avoid the need for an "end -of -pipe" facility. The system is illustrated in Figure 6D. It consists of a series of trays. The top tray is a sediment trap. Filter material is placed in the lower trays. Of several materials examined, the most suitable appears to be household fiberglass insulation. Limited tests indicate over 90% removal of metals and oil (McPherson,1992). As the insert requires frequent attention it should only be used where a maintenance person is located on -site. The insert has a bypass along one side should the filter material clog and is hydraulically designed so as to not compromise the Primary purpose of a catch basin, to get storm water into the drain system. The concept shown in Figure 6D is proprietary (Enviro-drain, 1992). Maintenance Inspect semiannually, and after major storms. Sediment should be removed from the settling basin when 4 inches accumulates and from the filter when 1I2 inch accumulates, or when there is still wafer in the basin or over the'filler 40 hours afar the storm. Remove floatables. Experience in Austin indicates the filter surface must be cleaned about twice each year by taking off the dried sediment. Failure to clean the filter regularly may result in the need to replace the entire media because of penetration of fines into the filter. It is more cost effective over the long term to clean the filter regularly as recommended. If there are open space areas in the tributary that are erosive or if construction is occurring, more frequent cleaning will be necessary. It may be necessary to replace the filter media after construction activity has ceased and the soils are stabilized. Consult Austin (1988), Truong (1989). and Shaver (1991) for additional design and maintenance criteria. REFERENCES Austin (City of).1990, "Removal Efficiencies of Stormwater Control Structures". Austin (City of), 1988, "Environmental Criteria Manual". Enviro-drain Inc, 199Z Kirkland, Washington. Galli, J., 1990, "Peat -Sand Filters: A Proposed Stormwater Management Practice for Urbanized Arras", Metropolitan Washington Council of Governments. McPherson, J., 199Z "Water Quality BMPs: Catch Basin Infiltration", presented to the APWA Stormwater Managers Committee, Tacoma, Washington. TC6 Industrial Handbook 5-53 March, 1993 Additional Information — Media Filtration Metropolitan Washington Council of Governments (MWCOG), March,199Z "A Current Assessment of Urban Best Management Practices. Techniques for Reducing Nonpoint Source Pollution in the Coastal Zone". Shaver, E-, 1991, "Sand Filter Design for Water Quality Treatment", Delaware Department of Natural Resources. Stewart, W., 1989, "Evaluation and Full -Sole Testing of a Compost Biofilter for Stormwater Runoff Treatment", presented at the Annual Conference of the Pacific Northwest Pollution Control Association. Tomasak, MD„ G.E- Johnson, and PJ Mulloy, 1987, "Operational Problems with a Soil Filtration System for Treating Stormwater", Minnesota Pollution Control Agency. Truong, H. V ,1989, —rhe Sand Filter Quality Structt„,Distri« of Columbia Government. TC6 i Industrial Handbook 5-54 March, 1993 Additional Information — Mao Filtration E acc _= Q —Cn c) • • 1 lQ ! C Ca © -0400 �, L CD..<.:. ---_=' CO CO c _ cc u c "cc A L01 --- jor -- -a. . c`) z ii p Q C 0 _ frr���l V i ._ f L:a LL L.7 1 ..QJ Q 1 TC6 1 Industrial Handbook 5 - 55 March,1993 Additional Information - Media Fsarawn :Low I C� C� C✓ Q '" '—' �'S'ct7tvtc�T :-2Ae? SASO GRAMCOVE.R SOLLDCOVE2 FLOW —i I ENTRANCE—, GROUND PAV ;G W MEN r" WWII .. • _ SAND OUMALL sEcrtov A • A ' Source: Shaver (1991) GRATE(FA9RIC PPE I OVER M%- I l GRATE OPL-ST G FIGURE 6B. LINEAL SAND FILTER LAMER -ENTRANCE W--S-+EO I AGGREGATE CLEAN our PIPE ENTRANCE r-� 1 TC6 1 Source: District of Columbia FIGURE 6C. VAULT SAND FILTER- Industrial Handbook 5 - 56 March,1993 Additional Information— Media F>faaton Catch Basin Grate �l r••••'v vu a�w� Source: McPherson (1992) FIGURE 6D. CATCH BASIN FILTER Industrial Handbook 5-57 TC6 March, 1993 Additional Information Media Filtration Sediment Trap Dr aim Pips 10 - - - -`♦` Outlet Structure Bottom of TDrop inlet Sedimentation A A Basin Section A. --------- -- (Gravel Not Shown) '♦ Sediment Trap -----------' -* To Outlet Structure 2" Gravel Layer Perforated PVC Pipe B. Over Pipe Wrapped in Geotextile Fabric SEDIMENT TRAP. Source: City of Austin FIGURE 6E. EXAMPLE RISER PIPE AND SEDIMENT TRAP DET AILS TC6 Industrial Handbook 5 - 58 March, 1993 Additional Information - meaamrem Sand Bed op 18" Min. 2" Gravel -7 Layer Geotextile Fabric Perforated PVC Pipes A. SAND BED PROFILE (WITH GRAVEL LAYER) 4" Perforated PVC Pipe Covered with Geotextile Fabric 18" Min. T Max. Slope 4:1 1" To 2" Sand Bed Gravel Layer Geotextile Fabric 120 Min. Max. 10' - 0" O.C. — B. SAND BED PROFILE (TRENCH DESIGN) TC6 Adapted from City of Austin (19w) FIGURE 6F. SAND BED FILTRATION CONFIGURATIONS ..� w.ab.. Industrial Handbook 5 - 59 Match, 1993 0 • B M P: OIL/WATER. SEPARATORS AND WATER QUALITY INLETS ............. f t wwater separators are designed to remove one spec group of contaminants: petroleum compounds and grease. However, separators will also remove floatmble debris and settle- able solids. Two general types of oiUwater separators are used: conventionalgravity separator and the coalescing plate interceptor (CpI). EXPERIENCE IN CALIFORNIA O'Vwater separators are in use throughout California at industrial sites. Oil/water separa- tors are used at all bulk petroleum storage and refinery facilities. A few jurisdictions require new commercial developments to install separators under certain situations that are environmentally sensitive. SELECTION C Applicable to situations where the concentration of oil and grease related compounds will be abnormally high and source control cannot provide effective control. The general types of businesses where this -situation is likely are truck, car, and equipment maintenance and washing businesses, as well as a business that performs maintenance on its own equipment and vehicles. Public facilities where separators may be required include marine ports, airfields, fleet vehicle maintenance and washing, facilities, and mass transit park -and -ride lots. Conventional separators are capable of removing oil droplets with diameters equal to or greater than 150 microns. A CPI separator should be used if smaller droplets must be removed. LV IITATIONS • Little data on oil characteristics in storm water leads to considerable uncertainty about performance. • Air quality pit (conditional authorization) permit -by -rule from DTSC may be required. DESIGN AND SIZING CONSIDERATIONS • Sizing related to anticipated influent oil concentration, water temperature and velocity, and the effluent goal. To maintain reasonable separator size, it should be designed to bypass flows in excess of first flush. CONSTRUCTIONANSPECTION CONSIDERATIONS • None identified. MAINTENANCE REQUIREMENTS • Clean frequently of accumulated oil, grease, and floating debris. COST CONSIDERATIONS • Coalescing plate material is costly but requires less space than the conventional Considerations Soils Area Required Slope Water Availability Aesthetics Hydraulic Head Environmental Side Effects Targeted Constituents Q Sediment Q Nutrients Q Heavy Metals Q Toxic Materials Floatable Materials Q Oxygen Demand ing Substances Oit & Grease O Bacteria. & Viruses LOW* to Haw S1 Acsntlmpact O Probable Low or Unknown Impact Implementation Requirements 0 Capital Costs 0 O&M Costs Q Maintenance O Training I High O Low TC1 Best Managemen Practices Industrial Handbook 5 - 60 March, 1993 • Additional Information — omater Separators and Water Duautyiniets General Infcmation Oil/water separators will be needed for a few types of industrial sites where activities result in abnormal amounts of Petroleum products lost_w exposed pavement, either by accidental sm5111 spills or normal dripping from the vehicle undercarriage. This will most likely be related to vehicle and mobile equipment maintenance activities. Separators may also be advisable where an area is heavily used by mobile equipment such as loading wharfs at marine ports. Limited data indicates od/water separators can reduce the oil/grease concentration below 10 mg/l (Lettenmaier, et al. 1985). Wet ponds, constructed wetlands, and biofilters will remove petroleum products but their reliability is uncertain where high concentrations of petroleum products may occur frequently. Also, BMPs that rely on vegetation may be damaged or become unsightly if high concentrations of oil and grease occur frequently. The sizing of separators is based upon the rise rate velocity of oil droplet and rate of runoff. However, with the exception of storm water from oil refineries there are no data describing the characteristics of petroleum products in urban storm water that are relevant to design: either oil density and droplet size to calculate rise rate or direct measurement of rise rates. Further, it is known (Silvennan,1982) that a significant percentage of the petroleum products are attached to the fine suspended solids and therefore are removed by settling not flotation. Consequently, the performance of otYwater separators is uncertain. The basic configurations of the two types of separators are illustrated in Figure 7A. With small installations, a conven- tional gravity separator has the general appearance of a septic tank, but is much longer in relationship to its width: Larger facilities have the appearance of a municipal wastewater primary sedimentation tank. The CPI separator contains closely spaced plates which enhances the removal efficiency. In effect, to obtain the same effluent quality a CPI separator requires considerably less space than a conventional separator: The angle of the plates to the horizontal ranges from 00 (horizontal) to 600, although 450 to 600 is the most common. The perpendicular distance between the plates typically ranges from 0.75 'to 1 inch. The storm water will either flow across or down through the plates, depending on the plate configuration. A related system is the water quality inlet illustrated in Figure 7B. It is essentially a conventional gravity separator but without the appropriate geometric configuration (see Design discussion below). Another name for this systems is a wet vault Water quality inlets have been found to be generally ineff=tive (Shipp, et ai., 1992) because the recommended size (200 to 400 ft /acne of tributary) is too small. To be effective, a water quality inlet must have the surface area and volume that is similar to that of conventional separators. They may exhibit odor problems during the summer because of the lack of bacterial degradation of accumulated organic matter and the lack of reaeration of the wet pooh. Facilities in Washington D.C. have been observed to have odor but. it has been noticeable only when the system is opened for inspection. The sizing of a separator is based upon the calculation of the rise rate of the oil droplets using the following equation (modified from API, 1990): Vp = 1.79 (dp - dc)d2 x 10-8/n (h) where: Vp = rise rate (ft/second) n = absolute viscosity of the water (poises) dp = density of the oil (gm/cc) do = density of the water (gm/cc) d = diameter of the droplet to be removed (microns) Industrial Handbook 5 - 61 March, 1993 • Additional Information — OiUWater Separators and Water Quality Inlets A water temperature must be assumed to select the appropriate values for water density and viscosity from Table 7A. The engineer should use the expected temperature of the storm water during the December -January period There are no data on the density of petroleum products in urban storm water but it can be expected to He between 0.85 and 0.95. To select the droplet diameter the engineer must identify an efficiency goal based on an understanding of the distribution of droplet sizes in Storm water. However, there is no information on the size distribution of oil droplets in urban storm water. Figure 7C is a size and volume distribution for storm water from a petroleum products storage facility (Branion, undated). The engineer must also select a design influent concentration, which caries considerable' uncertainty because it will vary widely within and between storms. To illustrate Equation 1: if the effluent goal is 10 mg/l and the design influent concentration is 50 mg/l, a removal efficiency of 80°% is required. From Figure 7C: this efficiency can be achieved by removing all droplets with diameters 90 microns or larger. Using a water temperature of 100C gives a water density of 0.998. Using an oil density of 0.898, the rise rate for a 90 micron droplet is 0.0011 feet per second. It is generally believed that conventional separators are not effective at removing droplets smaller than of 150 microns (API, 1990). Theoretically, a conventional separator can be sized to remove a smaller droplet but the facility may be so large as to make the CPI separator more cost-effective. Sizing conventional separator (modified from API, 1990). D = (Q/2V)05 (2) where: D = depth, which should be between 3 and 8 feet Q = design flow rate (cfs) V = allowable horizontal velocity which is equal to 15 times the design oil rise rate but not greater than 0.05 feet per second If the depth exceeds 8 feet, design parallel units dividing the design flow rate by the number of units needed to reach the maximum recommended depth of 8 feet. Equation (2) is simplified from equations in API (1990) based on a recom- mended width to depth ratio of 2. The constant in Equation (2) can be changed accordingly if a different ratio is as- sumed- Some engineers may wish to increase the .facility size to account for flow turbulence. See API (1990) for the design procedure. Then: • Calculate length, L = VD/V • Compute width, W = Q/(VD). This should be 2 to 3 times the depth, but not to exceed 20 feet • Baffle height to depth ratio of 0.85 for top baffles and 0.15 for bottom baffles • Locate the distribution baffle at 0-10L from the entrance • Add one foot for freeboard • Install a bypass for flows in excess of the design flow Determining the design flow, Q, requires identification of the design storm: The separator is expected to operate effec- tively at all flow rates equal to or less than the peak runoff rate of the design storm. The design storm need not be an extreme event, as is typically used in the sizing of flood control facilities. If sized to handle a storm frequency between the 3-month to 1-year event, the facility will effectively treat the vast majority of storm water that occurs over time. All events equal to or less than the 5-month event represents about 90% of the precipitation over time; designing for a 2-year TC7 JI Industrial Handbook 5 - 62 - March, 1993 Additional Information— OiUWater Separators and Water Quality Inlets event only. increases the amount of nmoff treated by about 5% ('increase from 90% to 95% of rainfall treated). For the design storm selected, calculate the peak runoff rate using the rational method. A_rmlication of the Conventional OilfWater c oarator Assume that a conventional oillwater separator is to be used to treat runoff from a I2 acre parking lot. Assume further it is to be sized to treat nmoff from a rainfall rate of 0-50 inchesthr (which translates to a runoff rate of 0.50 cfs/acre when the area is 100 percent impervious. Using the example above, the computed VP is 0.0011 ft/sec. Using Equation 2, V =15 x 0.0011= 0.0165 ft/sec which is less than 0.05 ft/sec; thus, D = (Q12V)0-05 = (lf2 x 0.05/(2 x 0.0165)) x 0.05 D = 3.8 & L = VD/VP = 0.0165 x 3.8/0.0011 L=57ft.. W = QV(VD) = 0.2540.0165 x 3.8) W = 4.0 ft, since W is less than 2 x D, increase width to W = 3.8 x 2 = 7.6 ft. Thus, a conventional oil/water separator sized to capture runoff from a 0.5 in/hr rainfall on a 1/2 acre parking lot would be: D -3.8 ft W=7.6ft L =57ft Si7iny CPT.. Manufacturers can provide packaged separator units for flows up to several cubic feet per second. For larger flows, the engineer must size the plate pads and design the vau1L Given the great variability of separator technology among manufacturerswith respect to plate tee, spacing, and inclination, it is recommended that the design engineer consult vendors for a plate package that will meet the engineer's criteria. Manufacturer's typically identify the capacity of various standard units. However, the engineer's design criteria must be comparable to that used by the manufacturer in rating its units. The engineer can size the facility using the following procedure. First identify the expected plate angle, H (as degrees), and calculate the total plate area required, A(ft2). A = Q/VpCosineH (3) CPI separators are not 100% hydraulically efficient; ranging from 035 to 0.95 depending on the plate design (Aquatrend, undated). If the engineer wishes to incorporate this factor, divide the result fiom Equation 3 by the selected efficiency. • Select spacing, S. between the plates, usually 0.75 to 1.5 inch. • identify reasonable plate width. W, and length, L. • Number of plates, N = A/WL. • Calculate plate volume, pv(ft3). 1 TC7 1 Industrial Handbook 5- . 63 March, 1993 Additional Information - owater Separators and Water Cuaiity iniets Pv = QU+ LCosineH)(WLSineH) (4) 12 • Add a foot beneath the plates for sediment storage. • Add 6" to 12" above the plates for water clearance so that the oil accumulates above the plates. • Add one foot for freeboard. • Add a forebay for floatables and distribution of flow if more than one plate unit is needed • Add after bay for collection of the effluent from the plate pack area. • For larger units include device to remove and.store on from the water surface. Horizontal plates require the least plate volume to achieve a particular removal efficiency. However, settleable solids will accumulate on the plates complicating maintenance procedures. The plates may be damaged by the weight when removed for cleaning. The plates should be placed at an angle of 450 to 600 so that settleable solids slide to`the facility bottom. Experience shows that even with slanted plates some solids will "stick" to the plates because of the oil and grease. Placing the plates closer together reduces the plate volume. However, if debris is expected such as twigs, plastics, and paper, select a larger plate separation distance. Or install ahead of the plates a trash rack and/or screens with a diameter somewhat smaller than the plate spacing. Recognizing that an oil/water separator also removes settleable solids, it can also be considered a wet vault (TC2). The engineer can use Figure 2B (See TC2) to estimate the efficiency of both the conventional and CPI separators. As Figure 2B does not include the effect of plate technology, a CPI separator should perform considerably better than indicated in Figure 2B for the same Vb/Vr ratio. See API (1990) for further design concepts for both the conventional and CPI separators. Maintenance Check monthly during the wet season and clean several times a year. Always clean in October before the start of the wet season. Properly dispose the oil. REFERENCES American Petroleum Institute (API), 1990, "Design and Operation of Oil -Water Separators", Publication 421. Aquatrend, undated, "Design Manual: Innova Sep Particle Separation System", Shawnee Mission, Kansas. Branion, R., undated, "Principles for the Separation of Oil Drops from Water in Gravity Type Separators", Department of �� Chemical Engineering, University of British Columbia. L.eueumaier, D. and J. Richey, 1985- "Operational Assessment of a Coalescing Plate Oil/Water Separator", Municipality Of Metropolitan Seattle. . Metropolitan Washington Council of Governments (MWCOG), March, 1992, "A Current Assessment of Urban Best Management Practices: Techniques for Reducing Nonpoint Source Pollution in the Coastal Zone". Silverman, G. 1982, "Wetlands for Oil and Grease Control", Tech Memo. 87, Association of Bay Area Governments. TC7 I ow Industrial Handbook 5 - 64 March, 1993 Additional information owwater Separators and Water Quality Inlets TABLE 7A. WATER VISCOSITIES & DENSITIES Density of �C Temperature Absolute Viscosity Density pure water in air `F (Poises) (siugs/ft.sec.) (8n✓CC) (lbs/tt3) 0 32.0 0.017921 0.00120424 0.999 62351 1 33.8 0.017343 0.00116338. 0999 62355 2 35.6 0.016728 0.00112407 0999 62358 3 37.4 0.016191 0.00108799 0.999 623W 4 39.2 0.015674 0.00105324 1.000 62360 5 41.0 0.015188 0.00102059 0999 62360 6 42.8 0.014728 0.00098968 0.999 62359 7 44.6 0014284 0.00095984 0.999 62357 8 46.4 0.013860 0.00093135 0.999 62354 9 48.2 0.013462 0.000904W 0.999 62350 10 50.0 0.013077 0.00097873 0999 62345 11 51.8 0.012713 0.00085427 0999 62339 12 53.6 0012363 0.00084870 0999 62333 13 55.4 0.012028 0.00080824 0999 62326 14 57.2 0.011709 0.00078681 0.999 62317 15 59.0 0.011404 0.00076631 0.999 62-IW 16 60.8 0011111 0.00074662 0.999 62299 17 626 0.010828 0.00072761 0.999 62289 18 64.4 0.010559 0.00070953 0999 62278 19 662 0.010299 0.00069206 0999 62.266 20 68.0 0.010050 0.00067533 0.998 622.54 1 TC7 1 Industrial Handbook 5 - 65 March,1993 Additional Information - o wvatlr separators aw %to Qwd4 kd to Clear Oil retention on Oil separation Flow ution well baffle skimmer compartment baffle Water outlet t I Water inlet an 'Liu- ;c v . 7t... - {4• Inspection and Grit/sludge sampling tee removal baffle CONVENTIONAL SEPARATOR Adapted from Romano. 1990 ater let \(/ Flow Adapted from Romano. 1990 COALESCING PLATE SEPARATOR baffle FIGURE 7A. _ CONVENTIONAL AND COALESCING PLATE SEPARATORS Industrial Handbook 5 - 66 March, 1993 Additional Information --- ojuwater separators and water amity Weis Primary Inlet,,. ccess ' _... � j nnannoiesl Raised Secondary Inlet for Large Storms Reinforced Concrete Construction Adapted from Schueler. 19V NOTE: 1. Size as conventional separator. 2. Design outlet orifice in elbow to limit outflow to the design rate for the unit. FIGURE 7B. WATER QUALITY INLET TC7 Industrial Handbook 5 - 67 March, 1993 1 m _E N 0 Co o m m a 0 0 n 0o 0 m � m � m om >m m� v C m v � m p o. E Co Additional Information— oiuwateir Separators and wahw Quality inlets 0 20 40 60 80 - 100 120 140 160 .180 200 Drop DISMO (micron) SIZE VOLUME - Sourcm Branion (undated) FIGURE 7C. SIZE AND VOLUME DISTRIBUTION TC7 11 Industrial Handbook 5.68 March, 1993 �f 1 JLB M P MULTIPLE -SYSTEMS INFILTRATION s FLOW TRENCH SV#" I A C 5, - -- DETENTION Mai,BASIN FLOW DESCRIPTION A multiple treatment system uses two or multiple systems have alreadymore of the preceding BMPs in series. A few been described; settling basin combined with a sand filter; settling basin or biofilter combined with an infiltration basin or trench, extended detention zone on a wet pond. EXPERIENCE IN CALIFORNIA The research wetlands at Fremont, California are a combination of wet ponds, wetlands, and grass•biofilters. SELECTION CRITERIA Need,to Protect a downstream treatment system Enhanced reliability Opdmum use of the site LMTATIONS • Available space DESIGN AND SIZING CONSIDERATIONS • Refer to individual treatment control BMPs CONSTRUCTIONIINSPECTION CONSIDERATIONS • Refer to individual treatment control BMPs MAINTENANCE REQUIREMENTS • Refer to individual treatment control BMPs COST CONSIDERATIONS Industrial Handbook 5-69 Considerations Soils Area Required Slo Water Availability Aesthetics draulic Head Environmental Side Effects Targeted Constituents sediment Nutrients Heavy Metals Toxic Materials Fkatable Materials Q Oxygen Demand ing Substances Q Oil & Grease 0 Bacteria & W-rvaes tlkek to Have SlgniAmnt Impact O Probable Low or Unknown Impact ImPlementation Requirements Capital Casts O&M Costs Maintenance Q Training ' High O Low TC8 Best Managemen Practices March, M Additional Information - Mumple-Systems Multiple systems may occur in series or by stacking vertically. Multiple systems that have been tried or that appear to be feasible are presented below. Stacked Wterns • Extended detention above wet pond: used extensively in the mid -Atlantic states. Recommended by several pracdoners because of the uncertainty about the performance of wet ponds. • Wet pond above sand filter: has been tried in Florida and Massachusetts and found wanting due to the clogging of the sand filter by settleable solids. Series . . ems • Extended detention basin - sand filter. standard system in Austin, Texas. Settling basin is needed to avoid excessive maintenance on the sand filter. • Detention basin - sand filter - wedand: Large system operating in Florida. • Wet pond - wetland: where an unusually high loading of sediment is expected, a full size wet pond, rather than just a forebay in the wetland, may be desirable to minimize the amount of sediment reaching the wetland where it would be more costly to remove. • Biofrlter - wet pond: Used frequently in the Pacific Northwes4 again to enhance reliability. • Biofilter - infiltration tr-ench: treatment of the storm water before it enters an infiltration system. • Oil/water separator - welnand or biofilter. oillwater separator used to protect the vegetated treatment system where high concentrations of oil may frequently occur. I TC8 1 Industrial Handbook 5 - 70 March, 1993