Connie Nelson, CFM, presented a presentation entitled ”Stormwater Infiltration using Dry Wells as a Low Impact Development (LID) Tool” at the Association of State Floodplain Managers (ASFPM) 2014 Conference in Seattle, Washington, on June 4, 2014.

Watershed urbanization can result in degraded water quality and increased flood risk due to hydromodification (larger peak runoff volume and shorter watershed residence time). Low Impact Development (LID) techniques can help reduce these impacts.  However, in many areas throughout California, the use of LID practices is challenging due to poor infiltrative capabilities associated with clay soils.   One solution to bypass these low-permeability clay zones is to use dry wells with associated pre-treatment designed to trap sediment and other pollutants.   This approach can recharge the groundwater and provide biofiltration to store and treat runoff and release it at a controlled rate to reduce the adverse impacts of hydromodification on waterways. This conjunctive use to capture stormwater and recharge the aquifer can also potentially reduce localized flooding and could meet numerous water resource management needs.

The City of Elk Grove, Cal/EPA’s Office of Environmental Health Hazard Assessment (OEHHA), Willdan Engineering, and consulting hydrologists have teamed together to study the potential environmental benefits and/or risks associated with the use of dry wells as a LID tool. The purpose of the project is to determine whether dry wells, in concert with other LID practices, are a cost-effective way to infiltrate stormwater, alleviate localized flooding, and recharge the aquifer without adversely affecting groundwater quality.  The project is located in Elk Grove, California and is funded by the California State Water Resources Control Board’s Proposition 84 Stormwater Grant.