The Elmer Avenue Neighborhood Retrofit transformed a typical residential street into a model "green street" by incorporating stormwater best management practices (BMPs) that capture and filter runoff from a 40-acre area. Before this project, the Sun Valley neighborhood had no pedestrian or stormwater infrastructure and was subject to frequent flooding. Now vegetated bioswales and a subsurface infiltration gallery that runs the length of the street allow up to 16 acre-feet of water to recharge groundwater supplies annually. These BMPs, along with rain barrels, trench drains, and permeable pavers on private property, improve the street's performance and aesthetic qualities, and serve as a demonstration project for both residents and policy makers.
7700 Block of Elmer Avenue
Los Angeles, California 91352
Stivers & Associates, Inc.
Council of Watershed Health
Stormwater management facility
4 acres (street and residential lots along one city block)
Captures stormwater from a 40-acre area
- ~$2.7 million - Total
- ~$1.8 million - Total construction
- $200,000 - Landscape construction on private property
- $200,000 - Construction of landscape elements in public right-of-way
Landscape Performance Benefits
- Infiltrates up to 5.4 million gallons of stormwater annually.
- Improves water quality by reducing concentrations of lead, copper and total suspended solids by 60%, 33%, and 18% respectively, by passing water through a catch basin sump before it enters the infiltration gallery.
- Reduces potable water use by 30% for homeowners with enhanced front yards and 10% for others, saving homeowners $120-$360 annually.
- Increased soil sequestration potential by approximately 6 times, resulting in 7.25 tons of carbon sequestered annually by soil and plant tissue.
- Educates at least 300 visitors annually on water issues and best management practices for stormwater.
- Increased resident satisfaction with their block's walkability from less than 2% of survey respondents in 2006 to 92% in 2011.
- Increased resident understanding that rain falling on local homes can be captured and used to supply the community with water.
- Only 60% of survey respondents agreed with this statement in 2006 compared to 100% in 2011.
- The underground infiltration gallery below Elmer Avenue is capable of capturing 750,000 gallons of runoff.
- Modified curbs and gutters direct runoff to 24 bioswales that collectively are capable of capturing and treating 115,000 gallons of runoff and add 1,728 sf of planted areas to the neighborhood. While the majority of infiltration occurs through the underground infiltration gallery, the bioswales provide an important visual demonstration of stormwater capture in an arid environment. They dramatically fill during rain events, after appearing dry the majority of the year.
- Bioswales are planted with drought tolerant native and Mediterranean plants, which require minimal irrigation once established, and a mulch layer to reduce evaporation.
- Adjacent to the sidewalks, 23 native trees were planted, along with southern California native and climate appropriate plants.
- 13 of the street's 24 homeowners opted to replace their traditional front yards with new "California-friendly" landscapes.
- Smart meters, 13 rain barrels (each with a 55-gallon capacity to capture roof run-off for reuse), and 6,000 feet of high-efficiency drip irrigation were installed at the participating private residences.
- Permeable paving surfaces, including 63 sf of permeable concrete and 1,560 sf of permeable pavers, were installed.
- Five solar-powered LED street lights collectively save 1,730 kW of power annually.
Concerns and the Community
Los Angeles faces considerable water supply challenges, relying heavily on imported water and having significantly reduced many of its local groundwater aquifers. To explore the safety and viability of using decentralized stormwater management and infiltration strategies to recharge groundwater supplies, Elmer Avenue Neighborhood was selected as the demonstration site for a Basin Water Augmentation Study (WAS) in 2000 by the Council for Watershed Health. Elmer Avenue was selected for the demonstration project because it fit various criteria: infrastructure improvements were needed, the soil type was conducive for infiltration, and there was political interest and support from the community for the project in this area. The design team spent considerable time understanding the existing landscape uses, maintenance regime, vegetation, and themes, so that the final design would meet community needs and create a sense of place. The community was encouraged to participate and have project ownership by being involved in design decisions and receiving training on maintenance practices.