Evaluation of Groundwater Supply Alternatives Within Bernal Subbasin

REGIONAL GROUNDWATER FACILITIES PROJECT FEASIBILITY STUDY ES-1 Zone 7 Water Agency December, 2025 EXECUTIVE SUMMARY Luhdorff & Scalmanini Consulting Engineers (LSCE) has prepared this Regional Groundwater Facilities Project Feasibility Study (Study) on behalf of Zone 7 Water Agency (Zone 7), and in coordination with the City of Pleasanton (City), to evaluate the potential for new groundwater production facilities to provide groundwater supplies to the City and provide drought reliability for Zone 7. The Study addresses the City’s and Zone 7’s combination of overlapping and separate project objectives including providing customers with safe water, addressing long-term water supply reliability challenges, capturing cost savings through economies of scale, continuing management of per- and polyfluoroalkyl substances (PFAS) and total dissolved solids (TDS), and protection of the Livermore Valley Groundwater Basin (Basin) given proximity to known PFAS footprints, and enhancing local drought resilience through additional regional groundwater production capacity. The City originally advanced its own Water Supply Alternatives Study (Brown and Caldwell, 2023) and was preparing to design and construct a two-well groundwater project identified through that process. From the City’s perspective, a primary objective of pursuing local groundwater development was a means of improving long-term water supply reliability, reducing reliance on purchased wholesale water and achieving long-term cost savings relative to Zone 7 wholesale supply rates. In parallel, Zone 7 and the City identified broader complementary regional and local objectives, including improving long-term water supply reliability, enhancing drought resilience, managing basin-wide PFAS and TDS risks, and maximizing the value of new groundwater infrastructure through coordinated planning. Based on these shared interests, the City and Zone 7 jointly evaluated whether a coordinated regional groundwater project could better advance both agencies’ objectives compared to planning and implementation of separate water supply projects. This joint evaluation led to the issuance of Request for Proposals (RFP) #2025-12, selection of LSCE as the lead consultant with technical support from Carollo Engineers, and development of this Feasibility Study. Since project initiation, Zone 7, the City, and the consultant team have conducted multiple workshops and technical meetings with the Zone 7 Board of Directors and City leadership to review hydrogeologic findings, define evaluation criteria, and advance alternatives to a feasibility-level assessment. A central technical driver of the Study remains the presence of PFAS within the Basin, requiring careful siting and design of new production capacity to expand local supplies while avoiding PFAS-impacted zones and protecting long-term basin sustainability. The Study applied a structured evaluation and ranking process that began with an initial screening of potential alternatives and advanced four representative project configurations for detailed evaluation as follows:  Project Alternative #1 – Tennis Park  Project Alternative #2 – Tennis and Hansen Park  Project Alternative #3 – Tennis and Del Prado Park  Project Alternative #4 – Tennis, Hansen, and Del Prado Park