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r7.74 n1•0/ <br />Water Boards <br />EDMUND G. Snow. JF. <br />GOVERNOR <br />iviRTTNEW RoDRIOUEZ <br />SECRETARY FOP <br />ENVIRONMENTAL PROTECTION <br />Central Valley Regional Water Quality Control Board <br />22 February 2017 <br />Linda Wilson <br />2606 Sheridan Way <br />Stockton, CA 95207 <br />TOYOTA TOWN INC., 610 NORTH HUNTER STREET, STOCKTON, SAN JOAQUIN <br />COUNTY, CASE# 390213 <br />California Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br />Board) staff have reviewed the Revised Work Plan for Additional Site Investigation (Revised <br />Work Plan) dated 6 January 2017, prepared and submitted on your behalf by ATC Group <br />Services, Inc. (ATC), for the Toyota Town, Inc. property at 610 North Hunter Street in Stockton <br />(Site). <br />On 17 September 2015, ATC submitted the Work Plan for Soil Gas Investigation which <br />proposed the collection of soil gas samples from temporary soil gas sampling points. In <br />response, Central Valley Water Board staff issued a letter dated 13 October 2015, requesting a <br />Work Plan Addendum to include a proposal for the installation and sampling of permanent soil <br />gas wells. As no Work Plan Addendum had been received, I issued a letter dated 18 November <br />2016 again requesting submittal of a Work Plan Addendum. The submitted Revised Work Plan <br />is in response to my November 2016 letter. <br />The Revised Work Plan proposes the following: <br />Installation and sampling of four (4) permanent soil gas wells. <br />Advancement of nine (9) borings (six [6] hydropunch and three [3] CPT) to delineate <br />groundwater between 40-60 feet bgs. <br />Advancement of four (4) borings to collect shallow soil for evaluation against Direct <br />Contact and Outdoor Air Exposure screening criteria outlined in the State Water <br />Resources Control Board's (State Water Board's) Low Threat Closure Policy (LCTP) <br />Advancement of one (1) boring in the vicinity of the former waste oil UST to collect soil <br />samples for analysis for required waste oil constituents. <br />Collection of soil to establish naturally occurring background metals concentrations. <br />I concur with the scope of work presented in the Revised Work Plan, provided the following <br />comments are incorporated: <br />1. In the Revised Work Plan, ATC proposes to advance six (6) hydropunch and three (3) <br />CPT borings (total of 9 borings) to a total depth of 60 feet bgs. Two (2) groundwater <br />samples are proposed to be collected between 40-60 feet bgs. The spacing and depth <br />of the proposed borings appears to be adequate to assess hydrocarbon impacts to <br />groundwater between 40-60 feet bgs, as requested. By 5 May 2017, please submit an <br />Assessment Report detailing the results of the proposed assessment activities. <br />KARL E. LONOLEY ScD, RE., CHAIR I PAMELA C. CREEDON P.C., BCEE, EXECUTIVE OFFICER <br />11020 Sun Center Drive i1200, Rancho Cordova, CA 95670 J www.waterboards.ca.govicentralvallay <br />RECYCLED PAPER