Infiltration of Urban Stormwater Runoff to Recharge Groundwater used for Drinking Water; A Study of the San Fernando Valley, California

Bren School of Environemental Science and Management, University of California at Santa Barbara


 

ABSTRACT

Our study explored the use of infiltration basins that capture urban stormwater runoff as a means of increasing the reliability of local groundwater resources used for drinking water in the San Fernando Valley of Los Angeles County. We first determined the volume of runoff that could be captured by infiltration basins using a calculation based on empirical studies. Model-based predictions were then used to evaluate the depth of soil necessary to sufficiently reduce stormwater contaminants in three different soil types. Finally, we analyzed  the cost-effectiveness of this management option by comparing costs of infiltration basins with the value of recharged groundwater, equivalent to the value of the marginal source of drinking water.

 

We found that infiltration basins with a surface area of 0.1 acre or 0.5 acre with a depth of two feet or three feet, located in a five-acre drainage area, could capture a volume of stormwater runoff ranging from 0.90 to 1.87 acre-feet per year. Our results indicated that smaller basins are more efficient at capturing runoff than larger basins. Given depths to groundwater ranging between 66 feet and 361 feet, depending on soil type, there was no contamination of groundwater from infiltrated stormwater containing the contaminants that we considered.

However, we determined that infiltration basins are not a cost-effective method of increasing drinking water supplies, as the costs of constructing and maintaining an infiltration basin far exceed the value of the drinking water that it provides. Our cost-effectiveness analysis focused on the value of stormwater infiltration solely as a method of augmenting drinking water supplies. The inclusion of benefits of infiltration as a stormwater management strategy may make this method cost-effective.

 

 

 

Have a question? e-mail Tessa Goff 

Donna Chralowicz, Alvaro Dominguez, Tessa Goff, Melissa Mascali, Emily Taylor

 

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if this link doesn't work try this link:Bren Master's Research page

Storm drain in downtown LA

infiltration basin at a Cal Trans BMP test site in LA