Piru Stormwater Capture Project

 Piru Stormwater Capture for Groundwater Recharge Project

The Piru Stormwater Capture for Groundwater Recharge Project combines water supply, water quality, and community outreach goals by modifying existing infrastructure to serve a new purpose. Urban stormwater runoff captured by the storm drain system diverts to a hydrodynamic separator that provides water quality pre-treatment before the water discharges to an adjacent infiltration basin. Water infiltrated in the basin is expected to reduce pollutant loads (as compared to untreated urban stormwater runoff) and will replenish the Piru Groundwater Basin. The Piru Groundwater Basin is the only water source available in the area; therefore, the project enhances regional self-reliance, a key component of climate change resiliency.


The Piru Stormwater Capture for Groundwater Recharge project captures stormwater runoff and nuisance flows from 35.8 acres of residential area in Piru community. All street flows from the project area (within yellow boundary) are conveyed via the storm drains (blue lines) to a hydrodynamic separator for treatment and cleaning. From the separator, clean water discharges into the Piru Spreading Grounds for infiltration and groundwater recharge.

The hydrodynamic separator, also known as continuous deflective separation (CDS) device, removes trash, sediment, oils and other stormwater pollutants before discharge onto Piru Spreading Grounds for infiltration and groundwater recharge. As the street discharge water swirls inside the CDS device, light and floatable pollutants like styrofoam, paper and oil, are captured at the top and heavy pollutants, like sediment, at the bottom of the separator.


What Causes Urban Stormwater Runoff Pollution?

Stormwater and urban runoff from impervious surfaces are primary sources of water pollution to creeks, rivers, and the ocean. Such runoff contains nutrients (nitrogen and phosphorus), bacteria, hydrocarbons, fine sediments, metals, trash, and other pollutants that are toxic to aquatic organisms and potentially harmful to human health. Storm drain conveyance systems carry stormwater and urban runoff from urbanized areas without allowing for natural treatment of the flow. Heavy loads of pollutants entering natural waterbodies can also increase bank erosion and downstream sedimentation with a significant negative impact on aquatic ecosystems. In addition, stormwater conveyance systems do not allow for natural infiltration into the soil to replenish groundwater.


vcpublicworks united water calwaterboards prop 1

Funding for this project has been provided in part through an agreement with the State Water Resources Control Board.