Tracer Test Planning For Groundwater Replenishment With Recycled Water In The San Fernando Basin For The City Of Los Angeles

This project focuses on developing a regulatory-compliant tracer test plan for the Hansen Spreading Grounds in the San Fernando Basin to support groundwater replenishment with purified recycled water. Led in partnership with the Los Angeles Department of Water and Power (LADWP), the study aims to confirm underground retention time and groundwater travel paths from the spreading facility to nearby production wells, in alignment with California’s Indirect Potable Reuse (IPR) requirements. The project builds upon foundational work from WRF project 5016 and incorporates updated hydrogeologic modeling and tracer selection strategies tailored to current site conditions. Although earlier versions of the project included the Tujunga site, the scope has been refined to focus exclusively on Hansen. The final tracer test execution at Hansen is expected to be conducted under a future phase. This study will provide critical inputs to LADWP’s IPR permitting process and contribute broadly to industry knowledge on tracer test planning for recharge operations.