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THA003 — Thatcher Company/1010 Industrial Rd, Stockton, CA/Work Plan for Groundwater Samples 2 <br />site constraints and professional judgement. The proposed ESA activities are described below. <br /> <br />3.1 Pre-Field Activities <br />Prior to commencing with field activities, the boring locations will be demarcated, Underground <br />Service Alert (USA call-before-you-dig) will be notified and a private utility location service will be <br />contracted to assess for the presence of underground utilities in the area where drilling is expected to <br />be conducted. An access agreement will be obtained from the current property owner and appropriate <br />permits will be acquired from the SJCEHD. <br /> <br />3.2 Boring Advancement <br />One boring will be advanced by EnProbe of Oroville, CA using direct push (GeoprobeTM) technology <br />to assess site lithology and determine the actual depth to water onsite. A continuous soil core will be <br />collected by placing a polyethylene sleeve inside the down-hole rod. The rod will be advanced to <br />approximately two feet below the groundwater surface which is estimated to be around 30 feet below <br />ground surface (bgs). A groundwater sample will be collected from this boring using polyethylene <br />tubing with a check valve. Tubing will be disposed of following sampling activities. The boring will <br />be backfilled with hydrated bentonite and/or cement slurry upon completion of soil and groundwater <br />sampling activities. GPS coordinates will be collected for each boring location. Cuttings shall be <br />containerized in 55-gallon drums pending offsite disposal. <br /> <br />3.3 Groundwater Sample Collection <br />Groundwater samples will be collected using direct-drive Hydropunchml equipment at four additional <br />locations. At each sampling location the HydropunchTm drive pipe, will be advanced approximately <br />three to eight feet into the groundwater table as determined by the direct push soil boring. Once the <br />HydropunchTm is advanced to the desired depth, the drive pipe will be withdrawn several feet allowing <br />groundwater to flow into the screen located within the drive pipe (the screen is not withdrawn with the <br />drive pipe). Following adequate time for groundwater to flow into the screen a groundwater sample <br />will be collected using a disposable polyethylene bailer or polyethylene tubing with a check valve. A <br />new bailer or tubing will be used at each sample location. The groundwater samples will be placed in <br />laboratory-provided containers, preserved as necessary, and placed on ice in a cooler pending delivery <br />to the laboratory for analysis. <br />Down hole equipment will be decontaminated with a distilled water/Alconox solution prior to use at <br />each well. Following completion of groundwater sampling, all boreholes will be abandoned using <br />cement slurry. <br /> <br />3.4 Analytical Testing <br />The groundwater samples will be delivered under chain-of-custody protocol to a California-certified <br />laboratory for analytical testing and analyzed for volatile organic compounds (VOCs) by Method SW <br />8260, nitrate as NO3 and chloride by EPA Method 300.0 and dissolved CAM 17 metals by EPA Method <br />200.8. <br /> <br />3.5 Report Preparation <br />Following completion of ESA activities analytical results for groundwater samples and chain-of- <br />custody records and laboratory reports will be submitted to the SJCEHD. <br />R:lProjectsITHA1003 - Stockton Phase ll ESAIReports1180202 - Work Plan for Hyrdopunch docx McGinley and Associates, Inc.