Evaluation of Groundwater Supply Alternatives Within Bernal Subbasin

Zone 7 Water Agency – Tennis Park Test Well Summary and Production Well Design Recommendations 1 Zone 7 Water Agency December 2025 1. INTRODUCTION Luhdorff and Scalmanini, Consulting Engineers (LSCE) have prepared this summary report documenting the hydrogeologic site investigation of the Pleasanton Tennis and Community Park (Tennis Park) and the construction and testing of the Tennis Park test well. The Tennis Park investigation was one of three site investigations conducted as part of the Regional Groundwater Facilities Project Feasibility Study, a joint project between Zone 7 Water Agency and the City of Pleasanton. Investigations and test well construction were also conducted at Del Prado Park and Hansen Park in the City of Pleasanton. The investigation of the Tennis Park site included drilling of an exploratory borehole to a depth of 820 feet below ground surface (bgs), construction of an eight-inch diameter test well completed to 770 feet bgs with eight screen sections between 195 feet and 760 feet bgs, pump testing, flow profiling, and water quality sampling and analysis. This report also includes production well design recommendations and flow rate estimates. 2. SITE SPECIFIC INVESTIGATION The primary purposes of the investigation of the Tennis Park site were to characterize subsurface lithology, characterize zonal water quality and flow characteristics, and collect the information necessary to design a sand-free and efficient well that could yield water in sufficient quantity and quality to meet project objectives. The Tennis Park test well site is located in the east area of the park along Valley Avenue in Pleasanton, CA (Figures 1 and 2). The Tennis Park test well was drilled and constructed by Nor Cal Pump and Well Drilling (Nor Cal) of Yuba City, California (CA C-57 License #908591). A copy of the permit for the drilling of the test hole and test well construction obtained from Zone 7 Water Agency is attached in Appendix A. A copy of the encroachment permit issued by the City of Pleasanton to work in the park is also included in Appendix A. Pump test development and pump testing was performed by North State Electric and Pump (North State) of Chico, California (CA C57 License #812678). A copy of the encroachment permit issued to North State by the City of Pleasanton is attached in Appendix A. Drilling commenced on February 5, 2025, and final well testing was completed on April 9, 2025. All work was conducted per project specifications and permitting requirements including traffic control, sound attenuation, and working hours unless variances were specifically granted by the City of Pleasanton. 2.1. Test Hole Drilling and Well Construction Nor-Cal drilled the test hole from ground surface to 820 feet bgs at a diameter of 8.75 inches using the direct rotary drilling method. Drill cuttings from the boring were collected at 10-foot intervals and described by LSCE. Representative samples were collected in one-gallon resealable plastic bags and “chip trays”. On February 7, 2025, after reaching the target depth, a suite of geophysical surveys were conducted in the borehole (Appendix A) by Pacific Surveys of Claremont, California. Using the descriptions of the drill cuttings and the geophysical surveys, LSCE developed a lithologic log of the materials