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ATC <br />ENVIRONMENTAL • GEOTECHNICAL <br />BUILDING SCIENCES • MATERIALS TESTING <br />1117 Lone Palm Avenue, Suite 201B <br />Modesto, CA 95351 <br />Telephone 209-579-2221 <br />Fax 209-579-2225 <br />www.atcgroupservices.com <br />August 4,2017 <br />Z054000033 <br />Mr. Alan Buehler <br />Central Valley Regional Water Quality Control Board <br />11020 Sun Valley Drive, Suite 200 <br />Rancho Cordova, California 95370 <br />Subject: Workplan for Additional Groundwater Delineation, Farmer Property/Former Toyota <br />Town Inc., 610 North Hunter Street, Stockton, California <br />Dear Mr. Buehler: <br />ATC Group Services LLC has prepared this workplan, on behalf of Ms. Linda Wilson, to perform <br />additional groundwater investigation activities at the subject site. The purpose of the additional <br />groundwater delineation is to determine if elevated concentrations of petroleum hydrocarbons detected in <br />the groundwater along the northern property boundary originate from the former USTs at the site. <br />The scope of work described by this workplan includes advancing three hydropunch borings and <br />collecting groundwater samples for analysis. <br />SCOPE OF WORK <br />Planning and Permits <br />ATC will obtain permits from SJCEHD for the advancement and installation of three soil vapor probes. <br />ATC will schedule field personnel and equipment, notify Underground Services Alert to locate <br />underground utilities as required, and perform other necessary field preparation and job start-up activities. <br />Boring Advancement <br />ATC will contract with a C-57 licensed drilling company to advance three hydropunch borings to <br />approximately 65 feet bgs to collect groundwater samples between 45 and 65 feet bgs. The borings will <br />be advanced at three locations between the former USTs and borings HP-5 and HP-6. Proposed boring <br />locations are shown on Figure 2. <br />Groundwater samples will be collected from the boreholes using a modified HydroPunche sampler. Prior <br />to groundwater sampling, a water level meter will be used to confirm that the drive rods do not contain <br />water. The sampler will then be driven to approximately three feet below the desired sampling depth, and <br />retracted three feet to expose the disposable schedule 20 polyvinyl chloride (PVC) screen and allow for <br />groundwater to enter the HydroPunch® sampler. The water sample will be collected by lowering a 3/4 <br />inch diameter stainless steel bailer through the drive rods to groundwater. The groundwater will be bailed <br />1