Santa Monica Airport Watershed Management Project City of Santa Monica

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2 City of Santa Monica Project No. 1CSM Prepared for: City of Santa Monica th St. Suite 300 Santa Monica, CA Prepared by: 555 S. Flower Street, Suite 4400 Los Angeles, CA Catherine Tyrrell with GeoSyntec Consultants 2566 Overland Avenue, Suite 670 Los Angeles, CA Ken Susilo

3 TABLE OF CONTENTS TABLE OF CONTENTS... i TABLES... i FIGURES... i APPENDICES...iii 1.0 Introduction and Summary Approach City of Santa Monica Airport Watershed Project Site Description Drainage Areas and Land Use Opportunities and Constraints Key BMPs and Treatment Trains Pollutants of Concern Pollutants and Beneficial Uses in Receiving Waters Land Uses and Associated Pollutants Airport Watershed Description Physical Description of Watershed Drainage Sub-Areas Land Uses, Pollutants, and BMP Opportunities and Constraints BMPs Evaluated Stakeholder Workshop BMP List for Further Analysis Worksheets and Photos Feasibility at a Planning Scale AIRPORT PROPERTY RESIDENTIAL AREA BUSINESS PARK OTHER Amounts and values of Avoided Potable Water Use Next Steps Capital Improvement Plan Conclusion TABLES Table 2-1 Land Uses and Associated Pollutants Table 2-2 BMPs and Targeted Pollutants Table 3-1 Sub-Drainage Description and Tributary Areas Table 3-2 LAND USE BMP ASSESSMENT: ISSUES AND OPPORTUNITIES Table 4-1 Water Quality Calculations Summary FIGURES Figure Figure Figure Figure i

4 Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure ii

5 Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure APPENDICES Appendix A Technical Memorandum Appendix B Penmar Water Quality Improvement and Runoff Reuse Project Appendix C County Department of Health and Services and City Building and Safety Division Health Standards Appendix D Recommended BMPs Design Performance Appendix E Workshop Presentation 6/20/2007 iii

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7 1.0 Introduction and Summary This report builds upon the City of Santa Monica s citywide Watershed Management Plan focusing on a priority watershed, the Santa Monica Airport Watershed, creating a more detailed Airport Watershed Management Plan with the following goals: Recommend implementable BMPs consistent with the City s Hierarchy of BMPs: Harvest, treat and reuse Harvest and infiltrate Treat and release Support the restoration of a healthier balance between the urban environment and the natural ecosystem, including the Santa Monica Bay; Be consistent with the City s guiding principles for sustainability. Specifically the report is based on the following tasks: Evaluate and develop alternative solutions for runoff management and present and discuss these alternatives in a workshop coordinated by city staff; opportunities for reuse will be included. Based on feedback from the workshop, provide an analysis of up to 10 BMPs in terms of construction constraints and costs, pollutants targeted, site feasibility based on information available (planning level). At least one of the BMPs will include down stream reuse opportunities. For the pertinent BMPs, provide information on treatment design and performance. Present information on the volume of water that can be reused and the avoided cost of potable water that it is replacing. 1.1 Approach To initiate the project, background information was provided by the City of Santa Monica, including the 1998 Hydrology Study, 1985 Master Plan of Drainage for the Santa Monica Municipal Airport, the 2005 Draft Santa Monica Airport Watershed Management Plan, and the Airport SWPPP and Monitoring Program. Information on soil type and porosity was provided in the Santa Monica Municipal Airport Master Plan of Drainage. FAA rules and regulations were considered in assessing potential best management practices BMPs for the airport drainage area. Specifically, the 1984 Santa Monica Airport Agreement with the Federal Aviation Administration (FAA) was reviewed for regulations on the types of improvements that may take place on the airport runway area. Restrictions include the runway/taxiway configuration, aircraft parking and tie-down space, and fixed base operator space, among others. 1-1

8 1.2 City of Santa Monica Airport Watershed Project Site Description The Airport Watershed is located in the southeastern corner of Santa Monica. It includes the Santa Monica Airport and surrounding both single family and multi-family residential land use, with a small amount of commercial areas and parks. The Airport Watershed, including the airport itself, totals about acres. The watershed flows to the Rose Ave. Drain in the City of Los Angeles and from there to Santa Monica Bay. Figure 1-1 shows the Santa Monica Airport Watershed. Figure 1-1 Santa Monica Airport Watershed Site Map 1-2

9 As shown in Figure 1-2, the Santa Monica Airport Watershed is part of a larger watershed all of which drains to the Rose Ave. storm drain adjacent to Penmar Park and Golf Course and exits to Santa Monica Bay. It is joined by the 16 th Ave. storm drain from within the city of Santa Monica and other city of Los Angeles Mar Vista hillside and Penmar adjacent drainage. Figure 1-2 Rose Ave Drainage Area Including the Santa Monica Airport Watershed Within the Santa Monica Airport Watershed, land uses can be seen in Figure

10 Figure 1-3 Land Uses Within the Santa Monica Airport Watershed 1.3 Drainage Areas and Land Use Opportunities and Constraints The Santa Monica Airport Watershed is composed of four drainage areas within the City. These are described in section 3.2. Section 3.3 provides the analysis of BMP opportunities and constraints. The watershed has been analyzed to determine locations for storm water reuse, retention, detention, and treatment. 1-4

11 1.4 Key BMPs and Treatment Trains Based on a stakeholder workshop held on June 20, 2007, 10 BMPs were chosen for more detailed analysis. They are: Airport Property: 1. Airport Avenue Landscaping 2. SMC Parking Lot Underground Retention 3. Zinc Hangar Runoff Management Residential Area: 4. Traffic Calming Landscape Modification 5. Pearl Street Rain Gardens 6. Grant Elementary School Underground Retention 7. Clover Park Underground Retention 8. Pico Boulevard Porous Pavement Business Park: 9. Business Park Bioretention Retrofit Other: 10. Penmar Water Quality Improvement and Runoff Reuse 2.0 Pollutants of Concern 2.1 Pollutants and Beneficial Uses in Receiving Waters The Santa Monica Airport Watershed is part of the greater Rose Ave. Watershed which, in turn, is part of the 414 square-mile Santa Monica Bay Watershed. The Santa Monica Bay Watershed reaches from the crest of the Santa Monica Mountains on the north from the Ventura-Los Angeles County line to downtown Los Angeles. From there it extends south and west across the Los Angeles plain to include the area east of Ballona Creek and north of Baldwin Hills. South of Ballona Creek, the natural drainage area is a narrow strip between Playa del Rey and Palos Verdes. The Santa Monica Bay has many beneficial uses, including fishing, swimming, surfing, diving and other REC-1 classified activities. Santa Monica Bay Beaches also have separate beneficial uses. The Los Angeles Regional Water Quality Control Board s 2002 Clean Water Act Section 303(d) List includes the Santa Monica Bay Offshore/Nearshore. The pollutants listed for this area include: Chlordane (sediment) 2-5

12 DDT (tissue & sediment) Debris Fish Consumption Advisory PAHs (Sediment) PCBs Polychlorinated biphenyls (tissue & sediment) Sediment Toxicity All are listed as low TMDL priority, with the exception of Chlordane which is listed as medium. The Santa Monica Bay Offshore/Nearshore pollutants listed on the (d) list includes a shorter list of the following pollutants: DDT (tissue and sediment), Debris, Fish Consumption Advisory, PCBs (Polychlorinated biphenyls) (tissue and sediment), and Sediment Toxicity. The beaches of Santa Monica Bay are listed separately from the receiving waters. The key pollutant listed is coliform (bacteria).the Santa Monica Bay Beaches Bacteria Total Maximum Daily Load (TMDL) was adopted on December 12, 2002 by the Regional Board (Resolution No ). As a result of these listings, the pollutant of greatest concern is bacteria. 2.2 Land Uses and Associated Pollutants Typical pollutants are associated with types of development (land use) that contribute to urban runoff. Table 2-1 below provides an overview of various land use classifications and the degree to which specified pollutants may be expected as a result of each land use. Type of Development (Land Use) Detached Residential Development Attached Residential Development Commercial/ Industrial Automotive Repair Shops Sediment/ Turbidity Table 2-1 Land Uses and Associated Pollutants Nutrients Organic Compounds Trash & Debris Oxygen Demanding Substances Bacteria & Viruses Oil & Grease Pesticides E E N E E E E E N E E N E P (1) P P (2) E N P (1) P (1) P(5) E P (1) P(3) E P (1) P N N E(4,5) E N N E N P Restaurants N N N E E E E N N Metals Hillside Development E E N E E E E E N 2-6

13 Parking Lots P(1) P(1) E(4) E P(1) P(6) E P(1) E Streets, Highways & Freeways Parks and Open Space E P(1) E(4) E P(1) P(6) E P(1) E E E N N E N N E N Source: Riverside County Flood Control and Conservation District, Riverside County Water Quality Management Plan for Urban Runoff (September 17, 2004). Abbreviations: E = Expected P = Potential N=Not expected Notes: (1) A potential pollutant if landscaping or an open area exists. (2) A potential pollutant if area includes uncovered parking areas. (3) A potential pollutant is land use involves animal waste. (4) Specifically, petroleum hydrocarbons. (5) Specifically, solvents. (6) Bacterial indicators are routinely detected in pavement runoff. The following descriptions are provided for each pollutant identified in Table 2-1 above: Sediments Sediments are soils or other surficial materials eroded and then transported or deposited by the action of wind, water, ice, or gravity. Sediments can increase turbidity, clog fish gills, reduce spawning habitat, lower young aquatic organisms survival rates, smother bottom dwelling organisms, and suppress aquatic vegetation growth. Nutrients Nutrients are inorganic substances, such as nitrogen and phosphorus. They commonly exist in the form of mineral salts that are either dissolved or suspended in water. Primary sources of nutrients in urban runoff are fertilizers and eroded soils. Excessive discharge of nutrients to water bodies and streams can cause excessive aquatic algae and plant growth. Such excessive production, referred to as cultural eutrophication, may lead to excessive decay of organic matter in the water body, loss of oxygen in the water, release of toxins in sediment, and the eventual death of aquatic organisms. Organic Compounds Organic compounds are carbon-based. Commercially available or naturally occurring organic compounds are found in pesticides, solvents, and hydrocarbons. Organic compounds can, at certain concentrations, indirectly or directly constitute a hazard to life or health. When rinsing off objects, toxic levels of solvents and cleaning compounds can be discharged to the MS4. Dirt, grease, and grime retained in the cleaning fluid or rinse water may also adsorb levels of organic compounds that are harmful or hazardous to aquatic life. Pesticides (including herbicides) are chemical compounds commonly used to control nuisance growth or prevalence of organisms. Excessive or improper application of a pesticide may result in runoff containing toxic levels of its active ingredient. Trash and Debris Trash (such as paper, plastic, polystyrene packing foam, and aluminum materials) and biodegradable organic matter (such as leaves, grass cuttings, and food waste) are general waste products on the landscape. The presence of trash and debris may have a significant impact on the recreational value of a water body and aquatic habitat. Excess organic matter can create a high biochemical oxygen demand in a stream and thereby lower its water quality. In addition, in areas where stagnant water exists, the presence of excess 2-7

14 organic matter can promote septic conditions resulting in the growth of undesirable organisms and the release of odorous and hazardous compounds such as hydrogen sulfide. Oxygen-Demanding Substances This category includes biodegradable organic material as well as chemicals that react with dissolved oxygen in water to form other compounds. Proteins, carbohydrates, and fats are examples of biodegradable organic compounds. Compounds such as ammonia and hydrogen sulfide are examples of oxygen-demanding compounds. The oxygen demand of a substance can lead to depletion of dissolved oxygen in a water body and possibly the development of septic conditions. Pathogens Pathogens and viruses ( measured by bacteria indicators) are ubiquitous microorganisms that thrive under certain environmental conditions. Their proliferation is typically caused by the transport of animal or human fecal wastes from the watershed. Water, containing excessive bacteria and viruses can alter the aquatic habitat and create a harmful environment for humans and aquatic life. Also, the decomposition of excess organic waste causes increased growth of undesirable organisms in the water. Metals The primary source of metal pollution in urban runoff is typically commercially available metals and metal products. Metals of concern include cadmium, chromium, copper, lead, mercury, and zinc. Lead and chromium have been used as corrosion inhibitors in primer coatings and cooling tower systems. Metals are also raw material components in non-metal products such as fuels, adhesives, paints, and other coatings. At low concentrations naturally occurring in soil, metals may not be toxic. However, at higher concentrations, certain metals can be toxic to aquatic life. Humans can be impacted from contaminated groundwater resources, and bioaccumulation of metals in fish and shellfish. Environmental concerns, regarding the potential for release of metals to the environment, have already led to restricted metal usage in certain applications. A comparison of the pollutants existing in the Santa Monica Watershed and receiving waters of the Santa Monica Bay with pollutants associated with land use activity in the Santa Monica Airport Watershed shows an overlap of common pollutants. Because of the wide range of land uses in the Santa Monica Airport Watershed, all of the pollutants listed can be considered of concern in the Watershed. However as BMPs are identified by location, one or another of the land uses and their specific pollutants of concern will dominate. In general the strategy is as follows: 1) where reuse is possible, treat to remove all pollutants to a Title 24 equivalency; 2) otherwise provide filtration or infiltration to remove bacteria and other pollutants in storm water. Table 2-2 provides a list of treatment control BMP categories identifying their effectiveness in treating various pollutants of concern. 2-8

15 Pollutant of Concern Table 2-2 BMPs and Targeted Pollutants Treatment Control BMP Categories (9) Veg. Swale /Veg. Filter Strips Detention Basins (2) Infiltration Basins & Trenches/Porous Pavement (3)(10) Wet Ponds or Wetlands Sand Filter or Filtration Water Quality Inlets Hydrodynamic Separator Systems (4) Sediment/Turbidity H/M M H/M H/M H/M L H/M (L for turbidity) Yes/No? Nutrients L M H/M H/M L/M L L U Yes/No? Organic Compounds U U U U H/M L L U Yes/No? Trash & Debris L M U U H/M M H/M U Yes/No? Oxygen Demanding Substances L M H/M H/M H/M L L U Yes/No? Bacteria & Viruses U U H/M U H/M L L U Yes/No? YES Oils & Grease H/M M U U H/M M L/M U Yes/No? Pesticides (non-soil bound) U U U U U L L U Yes/No? Metals H/M M H H H L L U Yes/No? Manufactured/ Proprietary Devices U 2-9

16 Abbreviations: L: Low removal efficiency M: Medium removal efficiency H: High removal efficiency U: Unknown removal efficiency Notes: (1) Periodic performance assessment and updating of the guidance provided by this table may be necessary. (2) Includes grass swales, grass strips, wetland vegetation swales, and bioretention. (3) Includes extended/dry detention basins with grass lining and extended/dry detention basins with impervious lining. Effectiveness based upon minimum hour drawdown time. (4) Includes infiltration basins, infiltration trenches, and porous pavements. (5) Includes permanent pool wet ponds and constructed wetlands. (6) Includes sand filters and media filters. (7) Also known as hydrodynamic devices, baffle boxes, swirl concentrators, or cyclone separators. (8) Includes proprietary stormwater treatment devices as listed in the CASQA Stormwater Best Management Practices Handbooks, other stormwater treatment BMPs not specifically listed in this report or newly developed/emerging stormwater treatment technologies. (9) Project proponents should base BMP designs on the Los Angeles County Stormwater Quality Best Management Practice Design Handbook. However, project proponents may also wish to reference the California Stormwater BMP Handbook New Development and Redevelopment ( The Handbook contains additional information on BMP operation and maintenance. (10) Note: Projects that will utilize infiltration-based Treatment Control BMPs (e.g., Infiltration Basins, Infiltration Trenches, Porous Pavement) without an underdrain will need to demonstrate with a property/project specific soils report that the soils are of the appropriate porousity. The selection of a Treatment Control BMP (or BMPs) for the project must specifically consider the effectiveness of the Treatment Control BMP for pollutants identified as causing an impairment of Receiving Waters to which the project will discharge Urban Runoff. 2-10

17 3.0 Airport Watershed Description 3.1 Physical Description of Watershed The Airport Basin Watershed is located in the southeastern corner of Santa Monica. It includes the Santa Monica Airport and both single-family and multi-family residential land use with a small amount of commercial areas and parks. The watershed flows to the Rose Avenue Drain in the City of Los Angeles and from there to Santa Monica Bay. Figure 3-1 shows the Santa Monica Airport Watershed Project Site. Figure 3-1 Santa Monica Airport Watershed Site Map 3-11

18 As shown in Figure 3-2, the Santa Monica Airport Watershed drains to the Rose Avenue storm drain adjacent to Penmar Park and Golf Course and exits to Santa Monica Bay. It is joined by the 16 th Avenue storm drain from within the city of Santa. Figure 3-2 Rose Avenue Drainage Area Including the Santa Monica Airport Watershed The Santa Monica Municipal Airport Master Plan of Drainage (May 1985) states that the soils in the drainage area are classified as 013 and 014, according to the Los Angeles County Flood Control District s classification of soil types. Soil type 013 has a low infiltration capacity and produces a maximum amount of runoff. Soil type 014 also produces a relatively high rate of runoff. These soil types were a factor in determining the feasibility of infiltration best management practices, as discussed in section

19 3.2 Drainage Sub-Areas The Santa Monica Airport Watershed is composed of four drainage areas. Table 3-1 Sub-Drainage Description and Tributary Areas Sub-Area Description Area [ac] DA 1-25th-S Airport DA 2-25th-N Northern Residential and Business Park DA 3 23 rd Cloverfield / 23 rd Street Residential DA 4 21 st Western Reidential 40.2 Total

20 Figure 3-3 Santa Monica Airport Watershed Drainage Areas 3-14

21 3.3 Land Uses, Pollutants, and BMP Opportunities and Constraints Figure 3-4 shows the Airport Watershed land uses. Figure 3-4 Santa Monica Airport Watershed Land Uses 3-15

22 Table 3-2 LAND USE BMP ASSESSMENT: ISSUES AND OPPORTUNITIES (Figures referred to follow the table) LAND USE ISSUE/CONSTRAINTS OPPORTUNITY Airport General Drainage Area 1 (DA1) - Airport Asphalt / Runways Parking Lots Majority of existing airport is impervious (Figure 3-5, 3-6, 3-7, 3-42, 3-43) Storm flows currently flood Airport Rd. Most of the Airport runs into the City of LA. Slurry Seal performed annually on taxiways. Impervious parking lots contribute pollutants into Per 1984 FAA agreement, can not remove asphalt on runway area (including taxiways and infill areas). Runoff from plane washing areas needs to be captured/treated. (Figure 3-6) Airplane tie-downs/airplane parking areas are on leased land to the owners until (Figure 3-11, 3-12 Pollutants include heavy metals, trash and debris, oil and grease, with potential for nutrients and pesticides, sediments, and oxygen demanding substances. Remove gunite area and create terracing to allow runoff to percolate in vegetation. (Figure 3-7) Culvert at end drainage point has potential to provide infiltration as treatment. (Figure 3-34, 3-35, 3-36, 3-37) Slot drains with underground treatment vault (vortex-type, separation screening units) near culvert at end drainage point. (Figure 3-38, 3-39, 3-41) Grass-crete near fire station Porous pavement, grass-crete, or underground retention at Santa Monica City College parking area (Figure 3-71, 3-72, 3-73). 3-16

23 LAND USE ISSUE/CONSTRAINTS OPPORTUNITY Hangers runoff. Metal roofs are source of pollution. Metal building/zinc roofs are a source of metals pollution. (Figure 3-28, 3-31) Insert landscaping/vegetation in parking lot medians to treat pollutants (Examples: Figure 3-15, 3-16, 3-17) Metal surfaces painted and maintained Possible use of planter boxes to capture and infiltrate roof runoff. (Figure 3-77) Outdoor Plane Parking Areas (Tie-down areas) Restaurants Fueling, Fuel storage, oil recycling Areas Airport Park The area is mostly impervious. Grease and oil from cooking, and leftover food may contribute bacterial pollutants. Oil recycling areas are provided onsite near the plane washing areas. Newly completed park provides Impervious plane parking areas contribute oil and grease pollutants. (Figure 3-10, 3-13, 3-40) Pollutants include pathogens, trash and debris, oil and grease, and oil demanding substances. Pollutants include heavy metals, organic compounds, trash and debris, and oil and grease. Adequacy of berming near oil recycling areas needs to be evaluated. (Figure 3-29, 3-30, 3-32). Plane washing areas (Figure 3-14) and gas station need to be reviewed for adequate capture. New Airport Park includes 4 infiltration basins, permeable asphalt is included in parking areas, and synthetic turf on soccer Direct runoff to slot drains with underground treatment vault (vortex-type, separation screening units). Direct runoff to slot drain to underground treatment vault. Review berming procedures for runoff. New park will serve as new infiltration site for a portion of the Airport watershed (Figure 3-74, 3-75, 3-76). 3-17

24 LAND USE ISSUE/CONSTRAINTS OPPORTUNITY Education (College building) treatment for runoff. fields. All runoff on new park site will be infiltrated, therefore this amount of treated runoff will reduce the total volume of water needed to be treated by future BMPs. Pollutants include heavy metals, trash and debris, oil and grease, with potential for nutrients and pesticides, sediments, and oxygen demanding substances. Water reuse for landscape irrigation. Landscape surrounding education buildings. 3-18

25 LAND USE ISSUE/CONSTRAINTS OPPORTUNITY Residential/ Commercial General Drainage Area 2 (DA2) Northern Residential Open Space (Clover Park) Clover Park parking lot drains to infiltration pit under park for treatment. Potential to store northern residential watershed in Clover Park (Figure 3-49, 3-50, 3-51). Education (Elementary School property) Often difficult to enter into agreement with school districts to treat offsite stormwater. Potential to store portion of northern residential watershed runoff (Figure 3-60, 3-61, 3-62, 3-63) Open Space (Recreational Fields) Currently, the field closest to the airport serves as a retention basin (Figure 3-49) during large storms when capacity in the 39 line exceeds the downstream 24 line capacity and water overflows into field. Ball fields can be used to treat, store, and reuse runoff from neighborhoods and commercial buildings (airport business park). (Figure 3-50) Major Streets (Ocean Park Blvd.) Smaller Residential Streets Residential runoff from household pollutants. Residential runoff from household pollutants. Residential runoff, including pathogens, nutrients, pesticides, sediments, trash & debris, oxygen demanding substances. (Figure 3-52, 3-53, 3-54, 3-55, 3-66, 3-67, 3-68, 3-69, 3-70) Residential runoff, including pathogens, nutrients, pesticides, sediments, trash & debris, oxygen demanding substances. (Figure 3-18, 3-24, 3-25, 3-56, 3-57, 3-58, 3-59, 3-64, 3-65) Combine traffic calming vegetation with infiltration/bioretention areas (Figure 3-21, 3-22, 3-78) Curb extensions throughout neighborhood streets. (Example: Figure 3-19, 3-20) Landscaping augmented with bioretention cells for infiltration and storm water treatment along streets and on residential properties. (Figure 3-23, 3-26) Combine traffic calming vegetation with infiltration/bioretention areas (Figure 3-21, 3-22, 3-78) Curb extensions throughout neighborhood streets. 3-19

26 LAND USE ISSUE/CONSTRAINTS OPPORTUNITY (Example: Figure 3-19, 3-20) Single-family residential Multi-family Neighborhoods adjacent to Ocean Park Blvd Education (School building) Residential runoff from household pollutants. Residential runoff from household pollutants. Pollutants include pathogens, nutrients, pesticides, sediments, trash & debris, oxygen demanding substances. Pollutants include nutrients, pesticides, sediments, trash & debris, with potential for pathogens, oxygen demanding substances, oil & grease. There may be limitations to diverting stormwater runoff to school areas due to human health concerns for students. Landscaping augmented with bioretention cells for infiltration and storm water treatment along streets and on residential properties. (Figure 3-23, 3-26) Curb extensions throughout neighborhood streets. (Example: Figure 3-19, 3-20) Landscaping augmented with bioretention cells for infiltration and storm water treatment along streets and on residential properties. (Figure 3-23, 3-26) Combine traffic calming vegetation with infiltration/bioretention areas (Figure 3-21, 3-22) Curb extensions throughout neighborhood streets. (Example: Figure 3-19, 3-20) Potential to use school fields to store and treat water from watershed. (Figure 3-60, 3-61, 3-62, 3-63) Commercial (Airport Business Park) Pollutants include heavy metals, trash and debris, oil and grease, with potential for nutrients and pesticides, sediments, and oxygen demanding substances. Connect roof runoff to landscaping and planter boxes. Residential General Drainage Area 3 and 4 (DA3/4) Southern and Western Residential Single-family residential Residential Lots in Single-family Areas Pollutants include pathogens, nutrients, pesticides, sediments, trash & debris, oxygen demanding substances. Area is hilly and may not be conducive to Landscaping augmented with bioretention cells for infiltration and storm water treatment along streets and on residential properties. (Figure 3-23, 3-26) Combine traffic calming vegetation with 3-20

27 LAND USE ISSUE/CONSTRAINTS OPPORTUNITY Multi-family Residential Multi-family Neighborhoods adjacent to Ocean Park Blvd treatment approaches infiltration/bioretention areas (Figure 3-21, 3-22, 3-78) Pollutants include nutrients, pesticides, Landscaping augmented with bioretention cells for sediments, trash & debris, with potential infiltration and storm water treatment along streets for pathogens, oxygen demanding and on residential properties. (Figure 3-23, 3-26) substances, oil & grease. Combine traffic calming vegetation with infiltration/bioretention areas (Figure 3-21, 3-22, 3-78) 3-21

28 LAND USE ISSUE/CONSTRAINTS OPPORTUNITY Other General Other Open Space Future Enhancements/ Alternatives Penmar Park and Golf Course Golf Course is owned by the City of Los Angeles so would need to coordinate potential BMPs included in the City of LA Penmar Water Quality Improvement and Runoff Reuse Project Concept Report. (Figure 3-33, 3-46, 3-47) Funding is a constraint. Health standards and water quality requirements for urban runoff treatment and reuse are currently at Title 22 standards, however alternative requirements may be proposed in the future. The City of Los Angeles has completed a concept report for Penmar Golf Course that includes a project that involves infiltration basins in Golf Course and the adjacent ball fields. The project may also include an impermeable pond for retention on Golf Course and water reuse. Runoff from the Airport watershed may be directed to the Golf Course for treatment (Figure 3-45, 3-47, 3-48). Coat roofs and downspouts instead of using zinc/copper for new development/redevelopment. Recycled Water used for toilets/urinals may be implemented if meets Title 22 regulations. Proposed underground storage of storm water may be used by fire department for fire fighting. 3-22

29 Figure 3-5 Figure

30 Figure 3-7 Figure

31 Figure 3-9 Figure

32 Figure 3-11 Figure

33 Figure 3-13 Figure

34 Figure 3-15 Possible location for biotention in The Business Park Figure 3-16 Possible location for biotention in The Business Park 3-28

35 Figure 3-17 Possible location for biotention in The Business Park Figure

36 Figure 3-19 Figure

37 Figure

38 Figure

39 Figure 3-23 Figure

40 Figure 3-25 Figure

41 Figure 3-27 Figure

42 Figure 3-29 Figure

43 Figure 3-31 Figure

44 Figure 3-33 Figure

45 Figure 3-35 Figure

46 Figure 3-37 Figure

47 Figure 3-39 Figure 3-40 Airport Avenue landscaping 3-41

48 Figure 3-41 Figure

49 Figure 3-43 Figure

50 Figure 3-45 Figure

51 Figure 3-47 Figure

52 Figure 3-49 Figure

53 Figure 3-51 Figure

54 Figure 3-53 Figure

55 Figure 3-55 Grant Elementary School on Pearl Street Figure rd and Pearl Street catch basin, facing west on 23 rd Street 3-49

56 Figure 3-57 Pearl at 31 st Street Figure 3-58 Pearl at 31 st Street 3-50

57 Figure 3-59 Figure

58 Figure 3-61 Figure

59 Figure 3-63 Figure

60 Figure 3-65 Figure

61 Figure 3-67 Santa Monica College Parking Lot Figure 3-68 Santa Monica College Parking Lot facing southwest. 3-55

62 Figure 3-69 Figure

63 Figure

64 Figure 3-72 Proposed locations for traffic calming landscaping 3-58

65 4.0 BMPs Evaluated 4.1 Stakeholder Workshop A workshop was held on June 20, 2007 convened by the City. At the workshop, the information included in Appendix E was presented. Based on feedback from the workshop a shortlist of BMPs was chosen for further analysis. These are described in section 4.2 below. 4.2 BMP List for Further Analysis A total of 10 BMPs was identified in this process that can be categorized into the following areas: Airport Property: 1. Airport Avenue Landscaping 2. SMC Parking Lot Underground Retention 3. Zinc Hangar Runoff Management Residential Area: 4. Traffic Calming Landscape Modification 5. Pearl Street Rain Gardens 6. Grant Elementary School Underground Retention 7. Clover Park Underground Retention 8. Pico Boulevard Porous Pavement Business Park: 9. Business Park Bioretention Retrofit Other: 10. Penmar Water Quality Improvement and Runoff Reuse Water quality calculations were performed based on the City of Los Angeles SUSMP (Standard Urban Stormwater Management Plan) methodology to provide design guidance on BMPs. This method determines the peak flow (Q PM ) or stormwater volume (V PM ) that should be mitigated as a result of ¾ of rainfall. Water quality calculations are summarized in Table 4-1 below. 4-59

66 Table 4-1 Water Quality Calculations Summary Sub-area Q PM [cfs] V PM [cf] WASE [cf] TMDL [cf] Drains to 21st ,694 36,565 23,847 Penmar Pk 23rd , ,225 96,016 Penmar Pk 25th-N , , ,589 Clover Pk to Rose 25th-S , , ,292 Airport Ave to Rose TOTAL 935, , ,745 Penmar Park ,403 22,542 14,702 To Rose See Appendix for Water Quality Calculations. 4-60

67 4.3 Worksheets and Photos Feasibility at a Planning Scale AIRPORT PROPERTY Airport Avenue Landscaping This proposed BMP will remove gunite along Airport Avenue and replace it with landscaping and trees. Due to the long length of the street, vegetated swales may be utilized within landscaping. Airport Avenue drains from east to west and there is an existing storm drain on Dewey Street. Targeted pollutants are sediment, oil and grease, and metals. There are no major construction constraints other than demolition, possible utility relocation, earthwork, landscaping, and drainage piping. The cost of this BMP is estimated to be roughly $440,000. Figure 4-1 Airport Avenue Landscaping 4-61

68 SMC Parking Lot Underground Retention As shown in Figure 4-2, this proposed BMP will build an underground extended retention basin (ERB) with pretreatment (for proprietary trash, suspended solids, oils, and etc.) underneath an existing Santa Monica College parking lot adjacent to the Airport Avenue. If soil conditions allow, this EDB would have a pervious membrane to allow infiltration. This BMP would collect drainage from other parking lots to the east and possibly from Airport Avenue. Low-flow runoff should be treated via infiltration, and high-flow runoff should be bypassed to a nearby storm drain system on Dewey Street or to an airport runway storm drain system which eventually drains to the Dewey Street storm drain. Targeted pollutants are nutrients, trash and debris, oxygen demanding substances, oils and grease, bacteria and viruses, and metals. There are no major construction constraints other than demolition, installation of BMPs, earthwork, paving, and drainage piping. The cost of this BMP is estimated to be roughly $1,380,000. Figure 4-2 SMC Parking Lot Underground Retention 4-62

69 Zinc Hangar Management As shown in Figure 4-3, this proposed BMP will build planter boxes along the sides of airport hangars to treat its roof runoff. The planter boxes should be designed to treat the low-flow runoff. High-flow runoff should overflow onto the adjacent areas as in the existing condition. Targeted pollutants are metals. There are no major construction constraints other than earthwork, landscaping, and if necessary, drainage piping. The cost of this BMP is estimated to be roughly $75,000. Figure 4-3 Zinc Hangar Runoff Management 4-63

70 4.3.2 RESIDENTIAL AREA Traffic Calming Landscape Modification As shown in Figure 4-4, this proposed BMP will modify existing traffic calming devices into street rain gardens. The existing landscape will be sunken into the ground to provide storage for water quality treatment. Curb cuts should be made so that the street surface flow would be directed into the rain gardens. The depth of depression for each rain garden should be determined by the water quality mitigation volume (V PM ) of its tributary area. There are total of nine possible locations identified in Figure 4-4. Targeted pollutants are sediment, oil and grease, and metals. There are no major construction constraints other than earthwork, landscaping, and if necessary, drainage piping and relocation of existing utilities. The cost of this BMP (for all nine locations) is estimated to be roughly $450,

71 Figure 4-4 Traffic Calming Landscape Modification (Yellow Highlighted Areas = Possible BMP Locations) Pearl Street Rain Gardens This proposed BMP will build two new street rain gardens along Pearl Street. Pearl Street is one of the major residential streets that carry relatively large amounts of surface runoff due to the lack of storm drain systems within the street. Possible BMP locations should 4-65

72 be identified so that the proposed location is strategic from a drainage point of view (i.e. downstream portion of street where surface flow is most concentrated) and is acceptable in terms of traffic and safety. Targeted pollutants are sediment, oil and grease, and metals. There are no major construction constraints other than earthwork, possible utility relocation, landscaping, and if necessary, drainage piping. The cost of this BMP is estimated to be roughly $200, Grant Elementary School Underground Retention As shown in Figure 4-5, this proposed BMP will build an underground retention basin with pretreatment (for proprietary trash, suspended solids, oils, and etc.) underneath an existing playing field at Grant Elementary School. The school is located near the upstream end of the Airport Watershed. Also, there is an existing storm drain system that drains south along the eastern property of the school site. Drainage from this storm drain should be diverted to a pretreatment device before discharging into the proposed underground retention basin. Low-flow runoff should be treated via infiltration; highflow runoff should be bypassed to the storm drain on 25 th Street. Targeted pollutants are nutrients, trash and debris, oxygen demanding substances, oils and grease, bacteria and viruses, and metals. There are no major construction constraints other than demolition, earthwork, repaving, and drainage piping. School buildings may cause some site constraints when diverting drainage from the adjacent existing storm drain system. The cost of this BMP is estimated to be roughly $795,000. Figure 4-5 Grant Elementary School Underground Retention 4-66

73 Clover Park Underground Retention As shown in Figure 4-6, this proposed BMP will build an underground retention basin (ERB) with pretreatment (for proprietary trash, suspended solids, oils, and etc.) underneath existing baseball fields at Clover Park. There is an existing storm drain system adjacent to the park on 25 th Street draining from north to south. Its drainage areas include the park itself, drainage on 25 th Street, and portions of The Business Park to the northeast and airport runway to the east. The existing storm drain on the 25 th Street should be diverted to a pretreatment device before discharging into the proposed underground retention basin. A soils analysis is recommended to determine the soil condition and infiltration capacity of Clover Park. Additionally, storm water stored in the underground retention basin may be reused to complement the park s irrigation demands. Targeted pollutants are nutrients, trash and debris, oxygen demanding substances, oils and grease, bacteria and viruses, and metals. There are no major construction constraints other than installation of BMPs, earthwork, possible utility relocation, storm drain connection, and drainage piping. The cost of this BMP is estimated to be roughly $2,155,000. Figure 4-6 Clover Park Underground Retention 4-67

74 Pico Boulevard Porous Pavement This proposed BMP will repave pedestrian crossings at one or more of the intersections along Pico Boulevard with porous pavement. Along Pico Boulevard, stormwater runoff flows from east to west at the sides of the street via gutter usually. Thus, porous pavements at the pedestrian crossings would be ineffective since it would have minimal contact area with the runoff. Targeted pollutants are sediment, oils and grease, and metals. There are no major construction constraints other than paving. The cost of this BMP is estimated to be roughly $180,

75 4.3.3 BUSINESS PARK Business Park Bioretention Retrofit As shown in Figure 4-7, this proposed BMP will retrofit the existing landscaping within The Business Park with bio-swales and rain gardens. These BMPs should be designed to treat the low-flow volumes based on its tributary areas. High-flow runoff can overflow onto the parking lots as in the existing condition. Targeted pollutants are sediment, oil and grease, and metals. There are no construction constraints other than demolition, earthwork, landscaping, and if necessary, drainage piping. The cost of this BMP is estimated to be roughly $1,250,000. Figure 4-7 Business Park Bioretention Retrofit 4-69

76 4.3.4 OTHER Penmar Park Water Quality Improvement & Runoff Reuse As shown in Figure 4-8, this proposed project will implement underground retention, infiltration, and possible reuse of storm water to address sub-regional water quality issues. This sub-regional BMP is expected to treat runoff from both the cities of Los Angeles and Santa Monica. Refer to the Penmar Water Quality Improvement and Runoff Reuse Project prepared by the City of Los Angeles and the City of Santa Monica, dated March 2007, for detailed project information and cost estimate. Figure 4-8 Penmar Park Water Quality Improvement & Runoff Reuse 4-70

77 4.4 Amounts and values of Avoided Potable Water Use In the scenarios above, avoided potable water use as a result of reuse occurs within the City of Los Angeles at Penmar Golf Course. As a result, no savings in dollars to the City of Santa Monica will occur. 5.0 Next Steps 5.1 Capital Improvement Plan Based on costs of BMPs, work with City staff to allocate costs by fiscal year. 6.0 Conclusion The intent of this report is to identify possible BMPs that will help improve the overall storm water quality of the Airport Watershed in the City of Santa Monica. Total of ten BMPs were identified and analyzed in terms of construction constraints and costs, pollutants targeted, and site feasibility at a planning level. A detailed engineering analysis is recommended for prospective BMPs to determine design-specific information. A cost-benefit analysis should be conducted for the proposed BMPs to help determine priority for each of the BMPs. The cost-benefit analysis should take into consideration, at the least, the drainage area, capacity, and cost of the BMPs. The prioritizing of BMPs should consider, at the least, the results of the cost-benefit analysis, existing BMPs, financial and timing logistics, and the City s needs. It is important to note that the entire Airport Watershed is one of the tributary areas of the Penmar Water Quality Improvement and Runoff Reuse Project, which is a sub-regional storm water quality improvement project. Thus, the Penmar Project is designed to mitigate much of the Airport Watershed s storm water runoff (V PM ). However, implementation of the recommended BMPs would improve the storm water quality closer to the pollutant source. Moreover, implementation of the recommended BMPs would likely reduce the design capacity and construction cost of the Penmar Project. Therefore, additional study is recommended to analyze the impacts of proposed BMPs on the design and cost of the Penmar Project. 6-71

78 APPENDIX A Technical Memorandum 6-1

79 APPENDIX B Penmar Water Quality Improvement and Runoff Project

80 APPENDIX C County Department of Health Services Health Standards

81 APPENDIX D Recommended BMPs Design Performance

82 APPENDIX E Workshop Presentation June 20, 2007

83