Groundwater Test Well Project
The District currently purchases and imports 100 percent of its potable water supply from the San Francisco Public Utilities Commission (SFPUC) Regional Water System (RWS). The District is investigating options to reduce reliance on the RWS and improve the reliability of its water supplies. Options being evaluated include developing groundwater as a supplemental or emergency supply.
On March 23, 2022 the District was notified by the California Department of Water Resources that the District’s “Potable Groundwater Supply Well Project” was awarded $6,623,100 for the Urban and Multibenefit Drought Relief Grant Program (Groundwater Project). The Groundwater Project, as described in the grant application, consists of a test well program followed by design, permitting, and construction of a potable groundwater production system including three wells, a treatment system, and connection to the District’s existing distribution system.
The District has done significant work related to assessing the availability of groundwater,
• A preliminary groundwater assessment study based on analysis of available information that concluded that a multi-well groundwater supply system tapping into aquifers of the underlying Basin could yield approximately 72 acre-feet per year (AFY) of groundwater when operated during the six-month dry season.
• A field assessment of existing well suitability for potential aquifer pumping tests that found no suitable wells; and
• A groundwater siting assessment that identified two potential locations for the new wells.
Based on the findings of the work it has completed to date, the District is pursuing the construction of tests wells and, depending on results from the test well program, new water supply wells.
The District’s Groundwater Test Well Project includes drilling, construction, development, and hydraulic testing of two groundwater test wells at two unpaved locations (sites) in Pacifica within the San Pedro Valley Groundwater Basin, which is in the Linda Mar Valley. The District completed an evaluation of various locations within the basin to assess their suitability for the test well project. The top two test well sites were at the Pacific Bay Christian School and the Sanchez Art Center, both located on Linda Mar Boulevard. Construction work for the Groundwater Test Well Project began in mid-May.
The Project consists of siting one groundwater test well at each of the sites. The two groundwater test wells are anticipated to be 5-inch nominal diameter PVC-cased wells with total depths of approximately 150 to 200 feet below ground surface (ft bgs), depending on site stratigraphy, groundwater quality, and drilling conditions.
Work will proceed first at the Pacific Bay Christian School site, followed by the Sanchez Art Center site.