Evaluation of Groundwater Supply Alternatives Within Bernal Subbasin

REGIONAL GROUNDWATER FACILITIES PROJECT FEASIBILITY STUDY 19 Zone 7 Water Agency December, 2025 3.4. Cost Estimates Each of the four project alternatives involves construction of either one, two, or three new production wells along with associated pipelines, pump stations, and the HCF upgrades. Capital and operating costs were estimated at a feasibility-level to allow comparison of the relative cost-effectiveness of each alternative. The following subsections summarize capital costs, annual O&M costs, and combined annualized costs, with detailed breakdowns provided in Appendices H and I. As Project Alternative #2 (Tennis and Hansen) is recommended as the most feasible option in this Study, specific refined capital cost estimates and operational costs are provided with the BODR and 10% design prepared by Carollo Engineers in Appendix J. Should agreement be reached between Zone 7 and the City to proceed with Project Alternative #2, the capital operational cost estimates will be further refined and accuracy improved as the project advances to Phase II design. 3.4.1. Capital Costs Carollo Engineers prepared feasibility-level capital cost estimates for each alternative in accordance with the Association for the Advancement of Cost Engineering (AACE) Class 5 standards. Class 5 estimates are appropriate for early-stage planning and carry an expected accuracy range of −30 percent to +50 percent. The Class 5 defined project costs shown in Figure 8 (single data points) include both direct construction costs and a 30 percent allowance for project soft costs (e.g., engineering, permitting, administration, and contingencies). The error bars represent the Class 5 uncertainty range applied to the underlying construction cost component only. Detailed assumptions and breakdowns are provided in Appendix H. The total capital cost estimates include well drilling and construction, pump equipment and pipelines, electrical and instrumentation, sitework, HCF facility upgrades, transmission pipelines between the new well facilities and the HCF, mobilization, contingency, and project soft costs. Off-site distribution system improvements downstream of the HCF that may be triggered by the increased capacity resulting from this Project were not included in this Study but are being evaluated separately by the City. Figure 8. Project Alternative Capital Cost Estimates and Ranges (Class 5) $16.6 $33.9 $33.2 $51.1 $0 $10 $20 $30 $40 $50 $60 Ca p i t a l C o s t E s t i m a t e s ($ M ) Alternative 1 (Tennis Park Well) Alternative 2 (Tennis and Hansen Park Wells) Alternative 3 (Tennis and Del Prado Park Wells) Alternative 4 (Tennis, Hansen, and Del Prado Park Wells)