17 - Laserfiche WebLink

Section 4: Preferred Alternative and Implementation Plan Water Supply Alternatives Study 4-7 DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document. Water Supply Alternatives Study-Draft Report.docx 4.4 Contingency Plan The City needs a contingency plan for how to proceed if the outcome of predesign activities indicate that implementation of Alternative 3 (Two New Wells) is less favorable than anticipated or not feasible due to groundwater quality issues and/or production limitations. For example, the City’s exploratory wells and/or Zone 7’s modeling may identify challenges related to siting new wells capable of meeting the City’s required production rates and water quality standards and preclude the implementation of Alternative 3. In that event, the City may pivot to its efforts to the next lowest cost option, which is completing the remaining design for PFAS treatment under Alternative 2 (Reduced Baseline). Previous work progressed the design to a 50% level. Thus, this shift, if necessary, can occur without impacting the overall schedule to getting an additional water supply into service as quickly as possible. Figure 4-2 summarizes the preliminary schedule for the contingency plan to shift from Alternative 3 implementation to Alternative 2 in terms of major project elements and milestones. The four major project elements identified in the figure include: 1.Predesign. Predesign activities are same as those for implementing Alternative 3 and involve: Siting of two well locations, including the City’s planned exploratory wells to test groundwater production rates and water quality and Zone 7’s planned update of its regional groundwater model and Well Siting Master Plan Seeking/securing external funding through grants and/or low-interest loans. 2.Design and Construction of the PFAS Treatment Facility and Well 8 Rehab. DBB is the assumed delivery method for design and construction of the treatment facility and Well 8 rehab. Activities related to this element include: Permitting, including NEPA/CEQA and the same permits as those required for Alternative 3, including permits through Bay Area Air Quality Monitoring District (air quality permits for generators), Pacific Gas & Electricity (new/modified service applications), Zone 7 (well drilling and abandonment permits), and the State Water Resources Control Board (construction stormwater). In addition, Alternative 2 requires agreements with DSRSD for PFAS treatment backwash disposal and Pleasant Unified School District (PUSD) for use as a construction staging area. Field investigations/special design coordination PFAS media prequalification PFAS vessel prepurchase PFAS treatment facility and Well 8 site design completion (i.e., remaining 50 percent of design) and construction 3.Design and Construction of Pipelines and Connecting Infrastructure. DBB is the assumed delivery method for design and construction of the new pipelines and connecting infrastructure required to tie the new wells into the City’s existing potable water distribution system. Activities related to this element include: Engineer procurement for design of pipelines and connecting infrastructure Permitting, including NEPA/CEQA Utility investigations, including potholing and geotechnical borings Design of pipelines and connecting infrastructure