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500 First Street, Woodland, CA 95695 • Tel. 530.661.0109 • Fax. 530.661.6806 • lsce.com <br />Well Capacity Estimates for Zone 7/Pleasanton Test Well Sites <br />An 8-inch diameter test well was constructed at Del Prado Park, Tennis Park, and Hansen Park. Each well <br />was developed, had step-drawdown pumping tests conducted, and had constant rate pumping tests <br />conducted for 8 hours. The data derived from the constant rate pumping tests, combined with data <br />regarding the range of expected regional groundwater levels, were reviewed for the development of full- <br />scale production well pumping capacity estimates at each location. <br />It should be noted that while well capacity estimates described below are based on some very specific <br />input values (e.g., for specific capacity, assumed static groundwater levels), the final production capacity <br />for each well cannot be precisely known until the large-diameter production wells are drilled and tested. <br />This is due in large part to considerable uncertainty in the well efficiency input parameter, which is as <br />much a function of the well efficiency and quality of work done by the drilling subcontractor as it is a <br />function of the engineering oversight and design specifications (e.g., filter pack gradation, screen slot size). <br />Thus, while the well capacity estimates described below may represent a best estimate at this time, they <br />could vary by several hundred gpm more or less than the values described below. <br />Background and Considerations in Low-End Well Capacity Estimates <br />The basis for the low-end production rate well capacity analysis is the occurrence of worst-case (critical <br />years with maximum municipal groundwater pumping) groundwater basin conditions. Groundwater <br />elevation contour maps were reviewed for recent critical drought years, including Fall 2015, Fall 2021, and <br />Fall 2022. In addition, total municipal well pumping and City of Pleasanton groundwater pumping were <br />reviewed for these three critical dry years, along with the last ten years overall (Table 1). Overall, the <br />lowest groundwater elevations occurred in the Fall of 2021 and Fall 2022, consistent with the highest rates <br />of total municipal groundwater pumping (over the past 10 years), ranging from 21,500 to 23,600 AFY, and <br />relatively high City of Pleasanton groundwater pumping between about 2,600 and 3,800 AFY.