The City of Los Angeles Department of Water and Power, in partnership with the Department of Public Works Bureau of Sanitation, recently developed the Groundwater Replenishment Master Planning Report (MPR) that identifies projects that can significantly increase the City’s recycled water use providing a local water supply and reducing the need for imported water.
A major component of the MPR is the recharge of up to 30,000 acre-feet per year of recycled water to be treated using an advanced water purification process that includes microfiltration, reverse osmosis, and an advanced oxidation process into the San Fernando Groundwater Basin. Multiple analyses were conducted to evaluate the impacts of the proposed project on the groundwater basin and demonstrate how the project will meet key criteria to gain approval from the California Department of Public Health (CDPH) to be permitted for recharge by the Los Angeles Regional Water Quality Control Board. The analyses conducted included:
- Evaluation of the capacity of the existing spreading basins to infiltrate the purified recycled water in coordination with Los Angeles County which owns and maintains the basins for capture and recharge local stormwater runoff;
- Modeling of the groundwater basin response to the additional recharge and extraction to establish the project can be configured and operated to (1) avoid unacceptably high mounding near the spreading basins, (2) avoid unacceptable drawdown near existing wells fields, and (3) demonstrate that the project can meet or exceed the minimum retention time specified in the draft CDPH regulations;
- Evaluation of long term runoff hydrology and modeling of the groundwater basin to demonstrate CDPH’s maximum Recycled Water Contribution requirement can be met; and
- Demonstration that the recycled water would be of higher quality than needed to assure that recharge of the basin would not degrade the water quality in the basin.