Evaluation of Groundwater Supply Alternatives Within Bernal Subbasin

REGIONAL GROUNDWATER FACILITIES PROJECT FEASIBILITY STUDY 33 Zone 7 Water Agency December, 2025 6. BASIS OF DESIGN AND FUTURE TREATMENT CONSIDERATIONS As part of this Feasibility Study, a Basis of Design Report (BODR) and associated 10 percent design drawings were prepared by Carollo Engineers for the recommended project alternative. The Final BODR (December 2025), included as Appendix J, establishes the technical basis, planning-level layouts, and implementation approach required to advance the Regional Groundwater Facilities Project into Phase II design and construction. The BODR confirms the overall project configuration evaluated in this Study, including development of new municipal supply wells at the Tennis Park and Hansen Park sites, associated well pump stations, raw water transmission pipelines, and key modifications required at the existing HCF to integrate the new groundwater supply. The BODR provides planning-level design criteria and preliminary layouts sufficient to support refinement of project costs and implementation strategy. Key findings and outcomes include:  Conceptual siting options and facility layouts for the Tennis Park and Hansen Park well pump stations, with recognition that final siting will be determined during subsequent design phases in coordination with City Planning, Parks, and Recreation staff and subject to City Council approval;  Preliminary production well design parameters, anticipated production capacities, and pump sizing based on test well data and planning-level assumptions, with acknowledgment that final production well performance and equipment sizing will be confirmed following full-scale well installation and testing;  Raw water transmission pipeline routing and sizing concepts that integrate new well production with the HCF, including provisions for phased implementation;  Conceptual reconfiguration of the HCF to accommodate expanded flow ranges, improve operational flexibility and redundancy, and integrate new process, electrical, and control systems;  Electrical, instrumentation, and control concepts adequate to support phased construction and future expansion; and  Planning-level opinions of probable capital and operation and maintenance costs for Project Alternative #2, refined from the Feasibility Study evaluation and suitable for use in Phase II budgeting and funding planning. The Class 4 cost information presented in the BODR reflects feasibility-level estimates intended to support alternative selection, funding evaluation, and project sequencing. These estimates will be further refined during Phase II design as final facility siting, production well performance, and detailed equipment selections are confirmed. Decisions Deferred to Phase II Consistent with a feasibility-level analysis, several key decisions are intentionally deferred and will be addressed during Phase II design and permitting, including:  Final siting of well pump stations within Tennis Park and Hansen Park;