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Exhibit A <br />WELLS 5A AND 8 PFAS TREATMENT AND <br />REHABILITATION PROJECT <br />BASIS OF DESIGN <br />SCOPE OF WORK <br />PROJECT OVERVIEW <br />BACKGROUND <br />The City of Pleasanton (City) hired Carollo Engineers Inc. (CONSULTANT) to perform the Water Quality <br />Evaluation Project in March 2019. The purpose of the project was to evaluate nitrification within the City's <br />potable water distribution system, perform a condition assessment of Wells 5, 6 and 8, and make <br />recommendations for improvements. <br />During the project, it was discovered through testing required by the State Water Resource Control Board <br />(SWRCB) Division of Drinking Water (DDW) that the City's groundwater supply at Wells 5, 6, and 8 <br />contained per- and polyfluoroalkyl substances (PFAS), which are currently being evaluated by the United <br />States Environmental Protection Agency (EPA) and DDW for possible regulation. As a result, the City <br />amended Carollo's contract for the Water Quality Evaluation to include a feasibility review of PFAS <br />treatment at the well sites. <br />In July 2020, the CONSULTANT finalized the Water Quality Evaluation Project, including PFAS treatment <br />feasibility. The results of the evaluation determined that: <br />1) PFAS treatment is technically feasible for the City wells. Further analysis is required to determine the <br />preferred siting of treatment (i.e. dedicated treatment at Well 5/6 and Well 8 sites or centralized <br />treatment at Well 8). <br />2) Significant rehabilitation to all three well facilities is required to extend their useful life. <br />3) Rehabilitation of well facilities and PFAS treatment should be implemented in a common project to <br />improve coordination and reduce cost. <br />4) The recommended improvements to address nitrification within the potable water distribution system <br />primarily consist of installing chloramine residual control systems at the City's two lower zone storage <br />tanks. The residual control systems are being implemented in a separate project. <br />pw://Carollo/Documents/Client/CA/Pleasanton/_Proposals/Well 5, 6 and 8 PFAS Treatment and Well Improvements 30DR/Exhibit A_Well 5, 6 and 8 PFAS Treatment and Rehabilitation Scope.dou <br />PAGE 1 of 10 <br />