Evaluation of Groundwater Supply Alternatives Within Bernal Subbasin

REGIONAL GROUNDWATER FACILITIES PROJECT FEASIBILITY STUDY 3 Zone 7 Water Agency December, 2025 1.2. Purpose The purpose of this Study is to:  Identify and evaluate feasible groundwater development project alternatives capable of producing a minimum of 7,000 AFY (including the City’s GPQ) under drought conditions as desired by Zone 7.  Assess the scope, costs, and pros/cons of wellfield configurations in terms of yield, water quality, operational resilience, project capital and O&M costs, and community impacts across dry, average, and wet years.  Provide Zone 7 and the City with a technically and financially sound basis for selecting a preferred alternative for consideration to advance to design, permitting, and construction (Phase II). 1.3. Approach to Study The Study was structured to follow the framework outlined in Zone 7’s Regional Groundwater Facilities Project RFP. Work began with exploratory drilling and aquifer testing at three candidate sites: Tennis Park, Hansen Park, and Del Prado Park, to principally establish baseline production capacity and water quality characterization. These results were supplemented by LSCE’s review of existing production and water quality records from existing production wells in the basin, as well as groundwater modeling efforts performed by Zone 7. Together, these efforts informed the development of a common set of project evaluation criteria shared by Zone 7 and City leadership, and LSCE to guide comparison of project alternatives. Two project evaluation criteria, groundwater production capacity and groundwater basin sustainability, were treated as pass/fail requirements given target project production values and to ensure compliance with Zone 7’s Alternative Groundwater Sustainability Plan (Alt GSP). Six additional criteria, including capital cost, O&M costs, community and environmental impacts, water quality and treatment impacts, implementation schedule, and operational flexibility, were weighted and scored to provide a transparent framework for evaluation of the project alternatives. Using this framework, four alternatives were advanced for detailed analysis, each representing different combinations of wells across the three candidate sites. Feasibility-level capital and O&M cost estimates were developed by LSCE with support from Carollo Engineers, providing the basis for comparative evaluation of alternatives and identification of a preferred configuration. 1.4. Zone 7 / City of Pleasanton Coordination Development of this Study has relied on the active support and direction of both Zone 7 and the City. Coordination was carried out through online workshops, technical meetings, and project communications in which Zone 7 staff, City staff, and the consultant team reviewed Phase I project data/findings, and established the framework for evaluating project alternatives. Following completion of the three project test wells, Zone 7 and LSCE presented the initial water-quality and production-rate results at the June 18, 2025 Zone 7 Board meeting. If an agreement to proceed with the regional groundwater project is reached, between the Zone 7 Board and City Council, subsequent Phase II design and construction activities will be initiated. Refer to Figure 2, which depicts the project communication milestones to date.