Evaluation of Groundwater Supply Alternatives Within Bernal Subbasin

EVALUATION OF GROUNDWATER SUPPLY ALTERNATIVES WITHIN BERNAL SUBBASIN APRIL 2026 / FINAL / CAROLLO CITY OF PLEASANTON 20 Table 8 Alternative Evaluation with Weighting Alternative Water Supply Reliability Water Quality Reliability Ease of Expansion for Treatment Community and Environmental Impacts Implementation Schedule Total Score Ability to deliver the City's annual GPQ (3,500 AFY) and assist in meeting max day demands by providing max day supply of 4,400 gpm for both existing and future conditions. Provide reliable water supply delivery during drought conditions, redundancy for short- term facility outages (planned and unplanned), ability to mitigate impacts of emergency outages occurring at the regional supply level, and reduce risk of low supply pressures at turnouts Ability to deliver water quality at or below current regulatory requirements Flexibility in source blending and locational delivery to aid in the City's management of water quality within the distribution season based on seasonal changes. Feasibility to expand new groundwater facilities for the purposes of additional treatment if required to meet future groundwater regulations Availability of space, ease to permit, ability to operate, and cost risk. Short-term impacts from construction activities. Impact categories include aesthetics, air quality, hazard materials, noise, traffic, and recreational use. Long-term impacts from new facilities park users, nearby residents, and the environment. Impact categories include aesthetics, air quality, hazard materials, noise, traffic, and recreational use. The anticipated time from project approval to water production. This includes pre-design, design, construction and corresponding permitting where applicable to each alternative. Potential for delays in implementation schedule and impacts to City. Criteria Weighting 5 5 3 4 3 Score Rationale Score Rationale Score Rationale Score Rationale Score Rationale Score Rationale Score Rationale Score Rationale Score Rationale Score Rationale Alternative 1 - Continue Purchase Water from Zone 7 2 Zone 7 has only committed to offset City GPQ via the delivery request process for the next 5 years. They have indicated they cannot commit to these deliveries for future conditions. 1 Does not improve any of the four reliability criteria. 5 Can meet current water quality regulations. 2 Maintains current status where City has no contractual control over source blends and Zone 7’s ability to adjust source blends are impacted by regional considerations. 5 Treatment expansion under this alternative occurs at the regional level. 5 Provides lowest risk since Zone 7 has multiple regional facilities and options to expand treatment to meet future regulatory requirements. 4 Project requires no construction of groundwater supply improvements at parks. It does require construction of City distribution improvements primarily in public right of way with moderate impacts requiring mitigation measures. 4 Project requires no new permanent facilities in parks. Project does require new turnout facility building (with chemical storage) on City owned parcel with moderate impacts. 3 Implementation schedule for City distribution improvements is approximately 3 years. 4 City distribution improvements represent moderate potential for delay (i.e. traditional right- of-way construction risks and turnout permitting with Zone 7 that is partially out of City’s control). Impacts of delay to City are low as delay does not change cost of supply from Zone 7 and distribution improvements are primarily needed for future conditions so there is schedule float. 66.5