Elmer Avenue Neighborhood Retrofit Demonstration Project


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Year: 2009

Type: Infiltration Trench and Bio swale

Scale: Neighborhood Scale

BMPs: Catch Basin, Infiltration Trench, Rain garden, Bioswales, Rain Barrel

Annual Rainfall: 14.93 in

Storm water Capacity: The system has the capacity to capture runoff of a 2-year storm.

Capacity of Bioswale: 115,000 gallons (15373 cb ft)

Capacity of Infiltration: 750,000 gallons ( 100260 cb ft)

Cost: $1,000,000-$5,000,000

Location: Sunny Valley, Los Angeles, USA

Client: City of Los Angeles and Residents of Elmer Avenue

Stakeholders Involved:

Residents of Elmer Avenue,

Guy Stivers & associates,

City of Los Angeles Bureau of Street Services,

Los Angeles and San Gabriel Rivers Watershed Control,

Landscape Architect – Edward Belden

Case Study Background:

The Elmer Avenue Neighborhood Retrofit Demonstration Project is a part of the Los Angeles Basin Water Augmentation Study and supported by multiple partners and is intended to improve local water supply and water quality. The project is unique in the region because it addresses storm water runoff at its source with seamless integration of private property and public right-of-way improvements. This integration was also the result of engaging the homeowners as critical partners throughout the project.

Type of System:

There are a variety of measures taken on Elmer Avenue to mitigate the problem of Flooding.

The project includes 4 acres containing 24 homes to manage storm water for approximately 40 acres which comes in from the catchment area north of the street and floods the whole neighborhood.


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The systems in place for storm water management includes:

Rain barrels, Rain gardens, Bioswales, Infiltration Trenches and Catch Basins.


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Infiltration trenches: There are 2 infiltration trenches installed on Elmer Avenue; the north gallery is 250 ft long and south gallery is 100 ft long.


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The storm water flowing to Elmer Avenue (run-on) from the 40- acre neighborhood to the north now enters catch basins that convey water into two infiltration galleries underneath the street. The bottomless catch basins allow particulates to settle out of the water before it enters the infiltration galleries. The two basins work in series, with water filling one before entering the next, which must also then fill before flow is conveyed to the gallery. The catch basins have no concrete bottoms, so some infiltration occurs there as well. The infiltration galleries below the street each consist of two 18-inch-diameter perforated pipes in a gravel bed five feet deep (Figure 5). Each gallery runs the 36-foot width of the street; the north gallery is 250 feet long, and the south gallery is 100 feet long

The infiltration trenches manage 87% of the storm water which is about 750,000 gallons.section1

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Bioswales: The bioswales guide the side walk and help infiltrate the water running down from the houses through driveways and overflow from rain gardens. 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. The bioswales provide an important visual demonstration of stormwater capture in an arid environment.


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Plant Palette:


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Sustainable Features and Measures:

The underground infiltration gallery below is capable of capturing 750,000 gallons of runoff.

13 of the street’s 24 homeowners opted to replace their traditional front yards with new “California-friendly” landscapes.

13 rain barrels (each with a 55-gallon capacity to capture roof runoff for reuse), and 6,000 feet of high-efficiency drip irrigation were installed at the participating private residences.

Permeable paving surfaces, including 63 sq ft of permeable concrete and 1,560 sq ft of permeable pavers, were installed.


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% survey respondents in 2006 to 92% in 2011.

Increased resident understanding that rain falling on local gomes can be captured and used to supply the community with water. Only 605 of survey respondents agreed with this statement in 2006 compared to 100% in 2011.

Full Presentation Link: Elmer Avenue water case study


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