Evaluation of Groundwater Supply Alternatives Within Bernal Subbasin

REGIONAL GROUNDWATER FACILITIES PROJECT FEASIBILITY STUDY 20 Zone 7 Water Agency December, 2025 a Point estimates (dots) represent construction costs plus 30% soft costs, which include engineering, permitting, administration, and contingency. b Error bars represent the AACE Class 5 accuracy range (−30% to +50%) applied to construcƟon costs only. c Costs are presented in 2025 dollars. d Refined capital cost estimates for Project Alternative 2 are provided with the BODR in Appendix J and will be further refined as the project advances to Phase II design if agreement is reached between Zone 7 and the City. d Costs for Alternatives 1 and 3 are presented for informational purposes only, as these alternatives cannot meet Zone 7’s drought year production target under the agency’s maximum allowable 75% runtime and have accordingly been eliminated from consideration. As shown in Figure 8, capital costs generally scale with the number of wells, ranging from approximately $16.5 million for Alternative 1 (one well) to about $51.0 million for Alternative 4 (three wells). Alternatives 2 and 3, each involving two wells, fall in the $33 million range. The error bars reflect the Class 5 cost uncertainty. 3.4.2. Annual Costs Annual O&M costs were estimated for each alternative based on a target production of 7,000 AFY, or the maximum annual production that the alternative is able to produce during drought years as shown in Table 4. Major categories include staffing, power, chemicals, well rehabilitation, pump repair and/or replacement, and electrical/instrumentation maintenance. Detailed assumptions are presented in Appendix I. As previously discussed in this Study, although Alternatives 1 and 3 are not capable of producing 7,000 AFY during drought years, the evaluation for these alternatives have been carried forward for informational and comparison purposes. In addition to direct O&M costs, capital costs were annualized using an Equivalent Uniform Annual Cost (EUAC) approach in which one-time project capital cost are converted into an equivalent stream of constant annual payments over the assumed facility life, enabling direct comparison with annual O&M costs. The calculation applies a Capital Recovery Factor (CRF), which is based on a 50-year project life and a 3 percent discount rate. The resulting annualized capital recovery values are then combined with O&M to develop total annual project costs on a $/AF basis. Figure 9. Project Alternative $/AF Annual Cost Estimates $403 $418 $416 $440 $559 $607 $643 $724 $0 $100 $200 $300 $400 $500 $600 $700 $800 An n u a l O & M C o s t E s t i m a t e s ($ / A F ) 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)