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9EDMUND G. BROWN JR. <br /> GOVERNOR <br /> COLIFON NI• <br /> Water Boards <br /> Central Valley Regional Water Quality Control Board <br /> 20 September 2018 <br /> Jeffrey D. Wingfield <br /> Port of Stockton California <br /> P.O. Box 2089 <br /> Stockton, California 95201 <br /> CENTRAL VALLEY WATER BOARD RESPONSE TO: DRAFT UST DATA GAP <br /> INVESTIGATION WORK PLAN, ROUGH AND READY ISLAND PORT OF STOCKTON, SAN <br /> JOAQUIN COUNTY, CALIFORNIA <br /> Dear Mr. Wingfield, <br /> California Central Valley Regional Water Quality Control Board (Central Valley Water Board) <br /> staff have reviewed the 30 July 2018 Draft UST Data Gap Investigation Work Plan (Draft Work <br /> Plan), prepared by Geosyntec Consultants on behalf of the Port of Stockton (Port). The Draft <br /> Work Plan was prepared in response to Central Valley Water Board letters dated 26 September <br /> 2017 and 16 February 2018 that addressed data gaps in the characterization of potential soil <br /> contamination at four former underground storage tank (UST) sites located at Rough and Ready <br /> Island (RRI) in Stockton, California (Site). <br /> The Draft Work Plan describes procedures for the collection and analysis of additional <br /> subsurface soil data to address data gaps at four former UST sites: (1) UST Site 517, (2) UST <br /> Site 605, (3) UST Site 8178, and (4) UST Site 9168. Subsurface soil data will be evaluated <br /> against the State Water Resources Control Board's Low-Threat Underground Storage Tank <br /> Case Closure Policy (LTCP). The results from the Work Plan will thus be used to determine <br /> whether the UST sites are eligible for `no further action' or require additional investigations or <br /> remedial actions. <br /> Central Valley Water Board staff have the following comments on the Draft Work Plan. <br /> Comments: <br /> Comment 1: UST Site 817B <br /> Issues: The Port proposes to collect soil samples at UST Site 817B from two soil borings <br /> adjacent to the previous highest areas of benzene detections (samples 817-D5 and 817-D7) <br /> that exceeded LTCP media-specific criteria in 2008. Soil samples from these two borings will be <br /> analyzed for benzene and total petroleum hydrocarbons (TPH) in the gasoline (TPH-g) and <br /> diesel (TPH-d) range and evaluated against LTCP media-specific criteria for petroleum vapor <br /> intrusion to indoor air and direct contact and outdoor air exposure. However, a review of <br /> historical data highlights additional issues the Port will need to consider in their evaluation for <br /> 1 <br /> 11020 Sun Center Drive#200,Rancho Cordova,CA 95670 1 www.waterboards.ca.gov/centralvalley <br />