Regional Groundwater Facilities Improvement Project – Phase I: Test Wells (Project 308-24)

Regional Groundwater Facilities Improvement Project – Phase I: Test Wells (Project 308-24)

As part of Zone 7 Water Agency’s (Zone 7) continuing effort to supply the Livermore-Amador Valley with safe, reliable water, Zone 7 and the City of Pleasanton (City) are working together to evaluate the feasibility of installing up to three additional municipal supply wells in the Bernal Subbasin of the Livermore Valley Groundwater Basin, in Pleasanton. Phase 1 of the project explores the feasibility of groundwater development in Pleasanton, at locations outside of the known footprint of PFAS concentrations. Specifically, individual test wells will be drilled and constructed at up to three different locations within the City of Pleasanton; these locations have been already developed for public use such as parking lot and landscaped areas. Each completed well will be tested for water production capacity and water quality in order to assess the feasibility of the construction of future production wells which would occur in a future phase of the project. A staging site near the City of Pleasanton’s S-6 booster pump station will be used to stage materials and equipment. See Figure 1 for locations. Construction at each test well location involves the following: (1) drill an exploratory boring to 800 feet below ground surface (bgs), (2) run a geophysical log to assess the lithology, and (3) construct an 8-inch diameter mild steel casing wells within the exploratory boring at depths based on the lithology encountered. The work will be completed by a C-57 licensed driller using mud rotary drilling techniques. A support truck, mud shaker, and watertight roll-off bin to contain spoils will also be used during construction at each site. Each test well project site will be approximately 120 feet by 100 feet. After the wells are constructed, they will be developed to ensure communication with the aquifer. Following well construction and development, the wells will be pumped and tested for several days to evaluate aquifer characteristics and collect waterquality samples which will be analyzed. Each well will be secured with a locking cap. The final well completion will consist of an approximately 18-inch diameter cover that will be installed flush with the surrounding area to secure the well. The well at Site A will be constructed in a parking lot and will be secured with a traffic-rated cover. The wells at Site B and Site C will be constructed within grass fields in the parks and will be secured using a standard cover. The staging location consisting of an area approximately 100’ x 40’ will be located off West Las Positas Boulevard near the City’s S-6 Booster Station and will be used to stage materials and equipment throughout the duration of the project. The work sites are located within City of Pleasanton owned public parks adjacent to residential neighborhoods. Zone 7 is coordinating with the City of Pleasanton parks department staff to minimize any inconvenience for public use of the park facilities. Traffic and pedestrian control plans will be approved by the city, and implemented, if necessary, at each site. Each work site will be enclosed and secured. The project will abide by the local noise ordinance and strict work start and stop times will be enforced. Implementation of noise attenuation structures, such as sound walls, may be used to meet noise ordinance requirements. Sound levels will be actively monitored on-site to ensure project noise does not exceed the local noise ordnances. The work is expected to start in late October 2024 and take 7 months. Each test well site is expected to take approximately 6 weeks to complete with intermittent breaks between sites and breaks between the construction and well testing phase. Once completed, the finished test wells will be situated in 3 feet by 3 feet utility vaults flushed with the surface and areas will be restored to the original conditions.

Pleasanton

Alameda

Citywide

Alameda