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EDMUND C. BROWN JR. <br />GO VE ANSE <br />NY 2 0 2011 CALIr0N:41411111114111111011.111r <br />Water Boards <br />"ae M ATTHEW RODRIQUEZ <br />SECRETARY ,OR <br />ChAWONVISAHAS PACHEC110E1 <br />Central Valley Regional Water Quality Control Board <br />17 May 2017 <br />Mr. Floyd Barnes <br />9744 Fountain Valley Drive <br />Stockton, CA 95209 <br />FORMER BARNES TRUCKING FACILITY, 1817 SOUTH FRESNO AVENUE, STOCKTON, <br />SAN JOAQUIN COUNTY <br />Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff <br />reviewed the Work Plan for Additional Site Assessment (Work Plan) dated 24 April 2017, <br />submitted on your behalf by Stratus Environmental, Inc. (Stratus). Staff also reviewed first <br />quarter 2017 groundwater monitoring data, submitted by Stratus via email dated 5 April 2017. <br />The former Barnes Trucking facility is located at 1817 South Fresno Avenue in Stockton (Site). <br />In the Work Plan, Stratus proposed the following tasks: <br />to install two (2) cone penetrometer test (CPT) borings (CPT-1 and CPT-2) to <br />approximately 90 feet below ground surface (ft bgs) for soil lithologic profiling <br />to collect between 3 and 5 depth discrete groundwater samples from separate borings <br />immediately adjacent to each of the CPT profile boreholes <br />to install two (2) off-site groundwater monitoring wells (MW-12 and MW-13) to <br />approximately 30 to 35 ft bgs with 15 feet of screen <br />to install and sample three (3) soil gas wells (SG-1 through SG-3), installed to a total <br />depth of approximately 5 ft bgs. <br />Central Valley Water Board staff has the following comments: <br />1. Existing Site monitoring wells are screened between 5 and 25 ft bgs, and between 15 <br />and 35 ft bgs. Collection of 3 to 5 depth discrete grab groundwater samples per CPT <br />boring to 90 ft bgs for vertical delineation is excessive. Collection of a single depth <br />discrete grab groundwater sample from each of the two (2) proposed deeper borings, <br />from depths approximately 10 feet deeper than existing shallow screened wells, based <br />on professional judgment, seems appropriate for this phase of vertical assessment. Use <br />of a CPT rig to collect a depth discrete grab groundwater sample from approximately 45 <br />ft bgs does not appear to be cost effective. Staff does not concur the use of a CPT rig, <br />nor does staff concur with collection of 3 to 5 depth discrete grab samples per boring. <br />Staff concurs with collection of one grab groundwater sample approximately 10 feet <br />below the deepest depth of existing Site well screens, approximately 45 ft bgs. <br />Professional judgment based on encountered lithology and field observations should be <br />used when selecting the final depth for collection of the deep depth discrete samples. <br />Staff are concerned about the proposed location of CPT-1 within the maximum <br />concentration area of the contaminant plume due to potential for vertical mobilization of <br />KARL E. LONGLEY SCE), P.E., CHAIR PAMELA C. CF1ECDON P.E., IBCEE, EXECUTIVE OFFICER <br />1/020 Sun Center Dove #200. Rancho Cordova, CA 95670 www.W2110,40ardS.Ca.90v/Centralvalley <br />C,3!. RFC YDS ED PA OEN