Reducing Stormwater Runoff and Pollution through Low Impact Development

A Review of Strategies in California and the

West Coast

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1. Introduction The purpose of this report is to conduct a general literature review on the use of some Low Impact Development (LID) strategies in stormwater management in California and the West Coast. The report describes various LID strategies and presents several case studies which highlight the effective use of LID techniques in reducing stormwater runoff volume and pollution. A Resource Directory listing of industrial contacts with experience in LID installation, LID technical manuals, and other LID-related information is attached at the end of the report. Low Impact Development (LID) is a site design strategy aimed at maintaining or replicating the pre-development hydrologic regime through the use of design techniques to create a functionally equivalent hydrologic landscape (EPA, 2000). The main elements of a functional hydrologic landscape include storage, infiltration, groundwater recharge, and the volume and frequency of runoff. LID strategies for stormwater management comprise a variety of lot-level land development techniques based on the principles of conservation, impact minimization, strategic timing, integrated small-scale site management and pollution prevention (Coffman, 2002). According to Coffman (2002), these principles may be viewed as basic steps for development:

1. Conservation planning techniques can be applied in the land use zoning process to define the development envelope.

2. Impact minimization strategies such as the reduction of impervious surfaces and pipes, maintenance of recharge areas and limits on clearing and grading activities may be used where practical.

3. Pre-development hydrologic regimes may be maintained or replicated through strategic routing (and timing) of flows on the site.

4. An integrated system of small-scale site management practices distributed throughout the site may be used to retain, infiltrate and treat storm runoff.

5. Pollution prevention and maintenance of LID stormwater management systems may be encouraged through public education and socioeconomic incentives.

Unlike conventional stormwater management techniques, which typically convey and store runoff in large centralized facilities located at the base of drainage areas, LID design strategies control stormwater at the source, through the use of an integrated system of small-scale controls distributed around the site (EPA, 2000). These small-scale controls can be integrated into the existing landscape relatively easily, including vegetated or landscaped areas, parking lots, buildings, and streets (Coffman, 2002). Generally, LID stormwater management strategies provide greater benefits over conventional stormwater management systems (NRDC, 1999; EPA, 2000; Coffman, 2002) (Table 1).

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Table 1. Comparison of conventional and LID strategies for stormwater management Factor Conventional Strategies LID Strategies Cost

High construction cost for stormwater management ponds, pipes, inlet structures, curb and gutter infrastructure.

Typically more economical than conventional approaches due to fewer pipe and below-ground infrastructure requirements. LID has also been shown to reduce the cost of retrofitting urban drainage.

Drainage

High runoff conveyance capacity and efficiency, which reduces potential for flooding, but decreases groundwater recharge and changes the natural hydrologic regime of the site.

Retains stormwater runoff onsite and promotes infiltration (therefore reduced flooding) and groundwater recharge through reduction of impervious surfaces and natural drainage features.

Environmental

Impacts associated with conventional systems include water quality degradation, stream channel erosion and adverse effects on aquatic and riparian biota.

Minimal disturbance to the natural hydrologic regime. Natural infiltration systems are more effective in removing pollutants from stormwater runoff, which leads to the improvement of stream habitat health.

Ease of Implementation

Less obstacles with development or building regulations since this approach is well-established in many areas.

LID can be retrofitted in highly urbanized areas, as well as newly developing areas, accommodating various lot sizes. However, the implementation of LID is often limited by development or building regulations enforced in the community.

2. Low Impact Development Strategies

Bioretention Systems

Bioretention systems manage and treat stormwater runoff by using a conditioned planting soil bed and vegetation to filter runoff stored in a shallow depression (PGC, 1999). Bioretention systems are often a combination of different functional components that work together to attenuate stormwater runoff and filter pollutants from runoff (Figure 1). Typical components found in bioretention cells (Table 2) include grass buffer strips, sand beds, ponding

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areas, an organic layer, planting soil and vegetation (EPA, 2000). Figures 2 and 3 show examples of bioretention systems applied along roadways and in parking lots.

Figure 1. A typical bioretention system (not drawn to scale) Source: Prince George’s County Department of Environmental Resources (1999). Low-Impact Development Design Strategies – An Integrated Design Approach. Table 2. Typical components in bioretention cells and their associated functions Source: EPA, 2000.

Component Function(s) Grass Buffer Strip Reduces the velocity of runoff and filters particulates in

the runoff. Sand Bed Facilitates aeration and drainage of the planting soil, as

well as the flushing of pollutants from soil materials. Ponding Area Stores excess runoff and allows for the settling of

particulates and evaporation of excess water. Organic Layer Acts primarily as a medium for biological growth for

micro-organisms to degrade petroleum-based pollutants.

Planting Soil Serves as a stormwater and nutrient storage zone. Some clayey soils also possess pollution adsorption properties.

Vegetation Removes water from the soil layer through evapotranspiration and removes certain pollutants through nutrient cycling.

Bioretention systems may require minor to major modifications for use in semi-arid and

arid watersheds in order to be effective. Bioretention systems may be designed with xeriscape vegetation, requiring little or no irrigation. In addition, the mulch layer may be replaced by gravel to reduce the need for irrigation (Caraco, 2000).

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Figure 2. Bioretention Swale (Seattle Public Utilities SEA Street Project) Source: Puget Sound Action Team (2005). Low Impact Development: Technical Guidance Manual for Puget Sound

Figure 3. Bioretention swale in a landscaped parking lot island. Source: Puget Sound Action Team (2005). Low Impact Development: Technical Guidance Manual for Puget Sound

Rain Gardens

Rain gardens are small detention and infiltration areas that use native vegetation to reduce stormwater runoff onsite (American Rivers, 2004). Rain gardens are a small-scale

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version of bioretention systems and are therefore highly suitable for retrofits in commercial and residential sites (Figures 4 and 5).

Figure 4. A rain garden in Douglas Ranch, Granite Bay, CA. Source: Office of Environmental Health Hazard Assessment (OEHHA) and the California Water and Land Use Partnership (CA WALUP). Low Impact Development: A Sensible Approach to Land Development and Stormwater Management.

Figure 5. Rain garden in Buckman Terrace housing development, Portland, OR. Source: Lipton, T. and Murase, R.K. (2002) Watergardens as Stormwater Infrastructure in Portland, Oregon. In Handbook of Water Sensitive Planning and Design. R.L. France (ed). Lewis Publishers: Boca Raton. Chapter I.6.

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Grass Swales

Grass swales (Figures 6 and 7) are dry grassed channels or shallow vegetated depressions that are strategically located to receive stormwater flow from surrounding areas and to divert surface runoff away from roads (American Rivers, 2004). Grass swales facilitate the infiltration of surface runoff by slowing down runoff velocity, and may also filter some pollutants in the runoff. Grass swales may be adapted to various site conditions but are mostly applied along residential streets and highways (EPA, 2000).

Figure 6. An example of a dry swale design. Source: Prince George’s County Department of Environmental Resources (1999). Low-Impact Development Design Strategies – An Integrated Design Approach.

Figure 7. “Dry” Grass Swale Source: Contra Costa Clean Water Program (2006) Stormwater C.3 Guidebook. Third Edition. October 2006.

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Permeable Paving

Permeable pavements allow water to infiltrate into underlying soils, therefore reducing storm runoff and promoting pollutant treatment and groundwater recharge (EPA, 2000). There are several types of permeable pavement systems, offering different infiltration capacities and structural strengths. Permeable pavement materials can be used for parking lots, driveways, sidewalks, utility access and residential roads (Figures 8a-c).

Porous concrete (surface where the cars are parked)

- Designed to minimize subgrade

compaction and maintain the infiltration capacity of underlying soils.

- Service life similar to conventional concrete if properly installed and maintained.

Aggregate pavers

- Compaction of the subgrade is required to maintain structural support.

- Capable of carrying heavy vehicle weight at slow speeds.

Plastic grid systems (e.g. Gravelpave)

Figures 8a – 8c. Examples of Pervious Pavement. Source: Hinman, C. 2005. Low Impact Development: Technical Guidance Manual for Puget Sound. January 2005. Puget Sound Action Team, Olympia, WA & Washington State University, Tacoma, WA.

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Green Roofs

Green roofs are vegetated roof systems consisting of multi-layered constructed materials as indicated in Figure 9a. Green roofs help to reduce the amount of impervious surfaces in an urban landscape, and can replace conventional rooftop gutters and drains that feed into sewers. The soil in the green roof helps to retain rainwater and filter out contaminants in the rainwater while the vegetation removes water from the roof structure through evapotranspiration. The performance of a green roof is closely tied to the design rainfall event it was constructed for; therefore designs should be developed for the storm events that most significantly contribute to runoff volume and quality problems in the watershed (EPA, 2000). Examples of green roofs constructed in California are shown in Figures 9b and 9c.

Figure 9a. An example of a green roof structure Source: Prince George’s County Department of Environmental Resources (1999). Low-Impact Development Design Strategies – An Integrated Design Approach.

Figure 9b. Green roof of Gap, Inc. in San

Bruno, CA Figure 9c. Green roof of Premier Automotive

Group in Irvine, CA Source: City of Los Angeles Environmental Affairs Department (2006). Green Roofs – Cooling Los Angeles: A

Resource Guide.

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Examples of Low-Impact Development Stormwater Management Strategies in California and the West Coast

Contra Costa County Stormwater Provision C.3 Implementation

From 2004 to 2006, municipalities in Contra Costa County phased in new and more stringent requirements on their stormwater NPDES (National Pollution Discharge Elimination System) permits. The new requirements, collectively known as Provision C.3, included an additional component, Hydrograph Modification Management. This component imposed restrictions on the amount and rate of runoff, requiring new developments to implement treatment and source control measures, and runoff flow controls so post-project runoff does not exceed pre-project rates or durations (CCCWP, 2006). Table 3 provides a summary of the application of C.3 requirements in different property categories. Table 3. Summary of C.3 requirements for Group 1 and Group 2 developments

Threshold Requirements Group 1 Commercial, industrial, or residential developments that create one acre or more of impervious surface, and projects on previously developed sites that result in addition or replacement, which combined, total an acre or more of impervious surface.

Developments that were considered complete before October 14, 2006 are required to implement treatment and source control measures as specified in the NPDES permit. New developments that occur on or after October 14, 2006 are required to implement treatment and source control measures as well as runoff flow control so that post-project runoff does not exceed estimated pre-project rates and durations.

Group 2 Commercial, industrial or residential developments that contain 10,000 square feet or less of impervious area.

Developments in this category are required to implement treatment and source control measures as stated in the NPDES permit.

Developments to which the C.3 requirements apply need to submit a Stormwater

Control Plan in addition to a Storm Water Pollution Prevention Plan (SWPPP). The latter contains temporary measures to control runoff, sediment, and other pollutants during the construction phase in construction sites of one acre or larger, while the former specifies permanent stormwater controls that need to be implemented for the entire life of the project. Measures listed in the Stormwater Control Plan need to be integrated into the site planning, drainage and landscape design processes.

The Contra Costa Clean Water Program has created a Stormwater C.3 guidebook to facilitate the adoption of the new requirements. It provides developers and planners with guidelines on the preparation of a Stormwater Control Plan, ways to minimize imperviousness on the building site, the selection of treatment and flow-control facilities, and examples of Low Impact Development, termed as Integrated Management Practices (IMPs), that can be adapted and implemented onsite to meet stormwater control requirements.

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The Guidebook also includes a section on sizing IMPs, which provides detailed procedures and sizing factors for calculating the required minimum size of IMPs on individual sites to meet the C.3 requirements. The IMP sizing calculator may be downloaded free at CCCWP’s website: (http://www.cccleanwater.org/construction/nd.php). City of Santa Monica Urban Watershed Management Program

The City of Santa Monica passed an Urban Runoff Pollution Control ordinance (Santa Monica Municipal Code Section 7.10) requiring a 0.75” reduction in urban runoff from all impermeable surfaces of all newly developed or retrofitted parcels within the city. This means that the projected runoff from proposed projects is required to be reduced by at least a volume equivalent to the surface area of all impermeable surfaces multiplied by 0.75”. The Ordinance also requires that new or retrofit development projects submit an Urban Runoff Mitigation Plan to the City of Santa Monica’s Department of Environmental and Public Works Management, describing the post-construction runoff control practices that will be implemented on-site. One of the objectives of the Urban Runoff Mitigation Plan is to promote the use of Best Management Practices (BMPs) associated with Low Impact Development and Smart Growth design principles (City of Santa Monica 2001/2005). The Department of Environmental and Public Works Management provides examples of BMPs that can be incorporated into project sites to reduce runoff, and integrated BMP systems for single-family or multi-family residential development or commercial development. City of Santa Monica “Green Streets” Program The Green Streets program was implemented in 2004 as part of the City’s efforts to incorporate sustainability into its annual street and sidewalk repair projects. Pervious concrete or pavers have been used to construct or retrofit several sidewalk, roadway and parking lot projects in the City. Conventional curb-and-gutter systems along these streets have also been replaced with porous concrete. Pervious concrete gutters allow storm runoff to percolate through the gutter into biofilter swales (Figure 10) or to underground storage/treatment trenches. Figure 10. Design schematic of a “green street” on Bicknell Avenue, Santa Monica, CA. Source: City of Santa Monica (2006) Watershed Management Plan.

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Virginia Avenue Park (2200 Virginia Avenue), Santa Monica, CA The redevelopment of Virginia Avenue Park included installing pervious pavers on parking lots (Figure 11a), a NetLawn® plastic grid system in the overflow parking area (Figure 11b), and slotted drains on the road to direct runoff away from surface to underground infiltration zones (Figure 11c).

Fig. 11a Fig. 11b Fig. 11c

Source: City of Monica Urban Watershed Management Program LID Factsheets

The City of Santa Monica also produces a Stormwater Management User Fee Report

annually, which contains listings of all parcels in the city and the stormwater fee associated with each parcel. The fee is calculated based on the size of the parcel, amount of runoff, and Parcel Billing Units (PBU). The PBU is derived from the relationship between parcel size and land use, which results in a directly proportional amount of runoff generated. For 2006-2007, the stormwater fee was $36.00 per PBU. More information about the City of Santa Monica’s Urban Runoff Management Program may be obtained at the City’s website: (http://www.smgov.net/epd/residents/Urban_Runoff/urban.htm). Seattle’s Street Edge Alternatives (SEA) Project

This natural drainage system project by the Seattle Public Utilities is located in the City of Seattle on 2nd Avenue NW, between NW 117th and 120th Streets (Figures 12a-d). It was completed in 2001 and involved the complete reconstruction of the street and its drainage area to reduce imperviousness and installation of stormwater detention ponds. The overall goal of this project was to reduce channel erosion and stormwater pollutant loading to a nearby stream (Pipers Creek) through the use of natural drainage systems. The project resulted in an 11 percent decrease in impervious areas, and was shown to prevent the discharge of all dry season flow and 98 percent of the wet season runoff (Horner et al., 2002). When compared to a conventional street design system in the City of Seattle, the SEA Streets alternative design resulted in a reduction in wet season runoff to Pipers Creek by a factor of 4.7 relative to the conventional street (Horner et al., 2002).

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Figure 12a. Before (inset) and after construction of the project.

Figure 12b. Curvilinear street design and structural grass strips to move water away from the road surface.

Figure 12c. “Flat curbs” provide additional driving room when necessary.

Figure 12d. Bioretention swales with native Pacific Northwest species.

Source: Seattle Public Utilities, SEA Streets Virtual Tour More information on the Street Edge Alternatives (SEA) Project and other natural drainage projects in Seattle may be obtained at the Seattle Public Utilities website: (http://www.seattle.gov/util/About_SPU/Drainage_&_Sewer_System/Natural_Drainage_Systems/index.asp). San Diego County Low Impact Development Handbook

On January 24, 2007, the County of San Diego adopted a revised Municipal Stormwater Permit which required jurisdictions in San Diego to regulate new and existing development and re-developments that increased impervious cover by 5,000 square feet to comply with stormwater management requirements. In addition, jurisdictions are required to encourage developments to incorporate minimal LID techniques into Priority Development Projects by January 2008 (County of San Diego, 2007).

An LID Handbook was developed to introduce and guide the use of LID techniques in initial LID projects. Specific regional or local LID requirements will be developed after feasibility

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and applicability criteria is established. These specific LID requirements will be incorporated into local codes and ordinances, and each jurisdiction is anticipated to have their own stormwater program with a comprehensive list of BMPs.

The Handbook addresses the relationship between LID practices and existing policies within the County such as Stormwater Management Planning, Water Conservation in the Landscaping Act, and the Multiple Species Conservation Program. The Handbook also discusses site assessment and planning, and provides LID site design examples for various land uses, including residential, commercial and industrial. In addition, the Handbook identifies key physical factors that may affect the function, design and performance of LID measures in San Diego. The Handbook may be reviewed at the San Diego’s Department of Planning and Land Use (DPLU) website: http://www.sdcdplu.org/dplu/docs/LID/Handbook.pdf Reduction of Impervious Surfaces through Parking Standards and Land Development Policies

San Diego has also developed new parking lot standards for commercial zones, aimed at reducing impervious surfaces. For instance, smaller parking spaces and driveways are required in intensive commercial zones.

In addition, San Diego’s Standard Urban Storm Water Mitigation Plan for Land Development and Public Improvement Projects (SUSMP) requires priority projects including new residential development, commercial developments, restaurants, hillside development and parking lots (exceeding 15 parking lots or 5,000 square feet) to implement appropriate BMPs to ensure to the maximum extent practicable that development does not increase pollutant loads from a project site and/or exacerbate urban runoff flow rates and velocities (County of San Diego, SUSMP Manual, 2003). The Manual is available through the County of San Diego’s Department of Public Works website: http://www.sdcounty.ca.gov/dpw/watersheds/land_dev/susmp.html. Los Angeles T.R.E.E.S Project

The T.R.E.E.S (Trans-Agency Resources for Environmental and Economic Sustainability) Project was initiated in 1997. Agencies and organizations participating in this effort include: TreePeople, USDA Forest Service/National Urban and Community Forestry Advisory Council, the Cities of Los Angeles and Santa Monica, EPA, Metropolitan Water District (MWD) of Southern California, the Los Angeles Urban Resources Partnership, the Southern California Association of Governments, Environment Now, ARCO Foundation, Angelica Foundation, Global Environmental Project Institute, CALFED-Bay Delta Authority, and the Los Angeles Unified School District (LAUSD).

The project involved a design charrette that brought together city planners, landscape architects, engineers, urban foresters and public agency staff members to design the retrofit of

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Los Angeles as a living watershed (http://www.treepeople.org/trees/default.htm). The design charrette developed a series of BMPs for industrial sites, commercial buildings, schools, apartments and single-family homes, which was published in a planbook (http://www.treepeople.org/trees/PBpreface.htm). In addition, a demonstration site was also constructed in South Los Angeles to highlight several of the BMPs that were recommended for a single-family home to function as a “miniature urban watershed” (http://www.treepeople.org/trees/default.htm), including vegetated swales and retention grading (Figures 13 and 14).

Figure 13. Swale in rear yard of demonstration

house. Figure 14. Retention grading in front yard of

demonstration house. Source: http://www.treepeople.org/trees/demo.htm

More information about the T.R.E.E.S Project may be obtained at this link: http://www.treepeople.org/trees/default.htm

3. Conclusions and Recommendations

This report provided a general overview of some low-impact development strategies utilized for stormwater management, including bioretention systems such as rain gardens, swales, permeable pavement and green roofs. The strategies listed in this report are some of the many available LID strategies that may be integrated into site design, or combined with other drainage area-based treatment controls to effectively reduce stormwater runoff and pollution. The second section of this report highlighted existing examples of stormwater management projects in California and the West Coast that made use of LID principles, as well as potential developments incorporating LID strategies. The examples provided are not exhaustive and it is recommended that further effort be directed toward examining the use of LID practices in stormwater management in California, and regional factors that determine the effectiveness of such practices.

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4. References

American Rivers. 2004. Catching the Rain: A Great Lakes Resource Guide for Natural Stormwater Management .

Caraco, D. 2000. Stormwater Strategies for Arid and Semi-Arid Watersheds. In The Practice of

Watershed Protection. T.R. Schueler and H.K. Holland (eds). The Center for Watershed Protection, Ellicott City, MD.

City of Los Angeles Environmental Affairs Department. 2006. Green Roofs – Cooling Los Angeles: A

Resource Guide. City of Santa Monica. 2001/2005. Working for a Cleaner Bay: Design Regulations, Construction

Practices, and Good Housekeeping Requirements for new building projects and existing properties to reduce urban runoff water pollution. Department of Environmental and Public Works Management, Environmental Programs Division.

City of Santa Monica. 2006. Watershed Management Plan. April 2006. City of Monica Urban Watershed Management Program LID Factsheets Coffman, L.S. 2002. Low-impact development: An alternative stormwater management technology.

In Handbook of Water Sensitive Planning and Design. R.L. France (ed). Lewis Publishers: Boca Raton. Chapter I.5.

Contra Costa Clean Water Program. 2006. Stormwater C.3 Guidebook. Third Edition. October

2006. EPA. 2000. Low Impact Development: A Literature Review. EPA-841-B-00-005. October 2000.

Office of Water, Washington, DC 20460. Horner, R., Lim, H., Burges, S. 2002. Hydrologic Monitoring of the Seattle Ultra-Urban

Stormwater Management Projects. Water Resources Series. Technical Report No. 170. November 2002.

Lipton, T. and Murase, R.K. 2002. Watergardens as Stormwater Infrastructure in Portland,

Oregon. In Handbook of Water Sensitive Planning and Design. R.L. France (ed). Lewis Publishers: Boca Raton. Chapter I.6.

Natural Resources Defense Council (NRDC). 1999. Stormwater Strategies: Community

Responses to Runoff Pollution. Chapter 12 – Low Impact Development.

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Office of Environmental Health Hazard Assessment (OEHHA) and the California Water and Land Use Partnership (CA WALUP). Low Impact Development: A Sensible Approach to Land Development and Stormwater Management

Prince George’s County (PGC). 1999. Low-Impact Development Design Strategies: An Integrated

Design Approach. Department of Environmental Resources, Programs and Planning Division.

Puget Sound Action Team. 2003. Natural Approaches to Stormwater Management: Low Impact

Development in Puget Sound. Olympia, WA. Puget Sound Action Team. 2005. Low Impact Development: Technical Guidance Manual for

Puget Sound Hinman, C. 2005. Low Impact Development: Technical Guidance Manual for Puget Sound.

January 2005. Puget Sound Action Team, Olympia, WA & Washington State University, Tacoma, WA.

Seattle Public Utilities, SEA Streets Virtual Tour: (http://www.seattle.gov/util/About_SPU/Drainage_&_Sewer_System/Natural_Drainage_Syste

ms/index.asp).

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COMPENDIUM OF LOW-IMPACT DEVELOPMENT RESOURCES

This is a non-exhaustive compendium of resources that provide information on Low-Impact Development, including green building businesses possessing expertise in LID design and construction. General Resources

Low Impact Development Center http://www.lowimpactdevelopment.org U.S. Environmental Protection Agency http://www.epa.gov/owow/nps/urban.html Stormwater Manager’s Resource Center http://www.stormwatercenter.net National NEMO Network http://www.nemonet.uconn.edu LID Urban Design Tools http://www.lid-stormwater.net National Association of Home Builders http://www.toolbase.org/index-toolbase.asp Regional Resources

California Stormwater Quality Association http://www.cabmphandbooks.com Caltrans Stormwater Management Program http://www.dot.ca.gov/hq/env/stormwater/index.htm Los Angeles County Department of Public Works http://ladpw.org/WMD/npdes/SUSMP_MANUAL.pdf City of Portland, Bureau of Environmental Services http://www.enviro.ci.portland.or.us/ City of Seattle http://www.ci.seattle.wa.us/util/surfacewater/bmp/default.htm County of San Diego Green Building Program http://www.sdcounty.ca.gov/dplu/greenbuildings.html Green Building in Alameda County, CA http://www.stopwaste.org/home/index.asp?page=7

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King County, Department of Natural Resources http://dnr.metrokc.gov/wlr Prince George's County, Maryland, Department of Environmental Resources http://www.goprincegeorgescounty.com/Government/ DER/PPD/pgcounty/index.htm Puget Sound Action Team http://www.psat.wa.gov Local (Santa Barbara) Resources

Green Building Alliance http://www.gballiance.com/intro.htm Firm Expertise

DesignARC Architect John Kelly/AIA Architect Kent Mixon Architect Poirer + David Architects Architect R.P.M Architects Architect Thompson Naylor Architects Architect Mike Gones Civil Engineer Allen Associates General Contractor Thomas P. Bortolazzo Construction, Inc. General Contractor Campanelli & Associates, Ltd. General Contractor Dexter’s Solar Radiant Energy Services Solar Contractor Renewable Energy Concepts Solar Contractor R&M Technologies Solar Contractor Isabelle Greene Landscape Architect NWA Landscape Architect Van Atta Associates Landscape Architect County Landscape & Design Landscape Architect Wilson Environmental Landscape Design Landscape Architect Grace Design Associates, Inc. Landscape Contractor

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