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December 19, 2022 <br /> Ms.Vera Fischer,P.G. <br /> Central Valley Regional Water Quality Control Board (Region 5S) <br /> 11020 Sun Center Drive#200 <br /> Rancho Cordova, California 95670 <br /> Re: Addendum to the Work Plan for Additional Off-Site Assessment <br /> California Tank Lines <br /> 3105 South El Dorado Street <br /> Stockton California 95206 <br /> Central Valley RWQCB Case#: 390541 <br /> Dear Ms. Fischer: <br /> On behalf of California Tank Lines and at the request of the Central Valley Regional Water Quality <br /> Control Board (CVRWQCB), Innovative Environmental Solutions (IES) has prepared this Addendum to <br /> the IES Work Plan for Additional Off-Site Assessment (Work Plan), dated September 9, 2022, to revise <br /> the scope of work described in the Work Plan. This addendum was prepared in response to the <br /> CVRWQCB Staff Letter dated October 11,2022. <br /> Historical assessment activities at the Site have defined two potentially separate water bearing zones, <br /> defined as A zone and B zone. The A zone describes the shallow groundwater interval that occurs <br /> approximately between 17 and 30 feet below ground surface (bgs). The B zone describes the next water <br /> bearing interval that occurs approximately between 40 and 60 feet bgs. The Work Plan proposed the <br /> installation of three groundwater monitoring wells, located off-site to the south and southeast, in an <br /> attempt to provide lateral delineation of petroleum impacts to groundwater in the B zone. In the October <br /> 11, 2022, CVRWQCB states that "staff observes a down-ward migration of petroleum hydrocarbons as <br /> the plume migrates away from the source. Collection of groundwater data from below 60 ft bgs is needed <br /> for vertical delineation." <br /> In the Work Plan, IES proposed a scope of work that included the installation of three off-site <br /> groundwater monitoring wells MW-1513, MW-16B and MW-1713. Due to the observed down-ward <br /> migration discussed above, the revised scope of work presented in this Addendum to the Work Plan <br /> includes three additional wells with deeper screened intervals co-located with the originally proposed <br /> wells MW-15B through MW-17B. Additional details follow below. <br /> 5.0 REVISED PROPOSED SCOPE OF WORK <br /> In preparing the Work Plan and this Addendum IES reviewed information available on the GeotrackerTM <br /> website regarding RWQCB Case #391024, California Global Id. T0607700844, Pacific Pride South El <br /> Dorado (Pacific Pride). Pacific Pride is a leaking underground storage tank case adjacent to the subject <br /> California Tank Lines Innovative Environmental Solutions <br /> Addendum to Work Plan - 1 - Encinitas,California <br />