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San Joaquin County Public Health Services <br /> July 23, 1992 <br /> Page 2 <br /> locations are determined to better represent any hypothetical leak plumes. Assuming <br /> the bottom of the tank is 10 feet or less below the ground surface (BGS), the borings <br /> will be 15 feet deep. A map showing the proposed locations of the soil borings is <br /> attached. <br /> Task 3: Utility Clearance <br /> Prior to the start of drilling activities, a utility clearance will be performed to <br /> determine the presence or absence of underground obstructions. The utility <br /> clearance will consist of identifying the locations of the soil borings, contacting <br /> Underground Service Alert (USA) to mark utilities in any public right-of-ways, and <br /> field clearance by qualified McLaren/Hart field personnel. <br /> Task 4: Soil Sampling and Analyses <br /> Borings will be drilled by a qualified subcontractor using a hollow-stem auger under <br /> the supervision of a registered geologist from McLaren/Hart. Drilling locations will <br /> be confirmed following completion of the utility clearance. Soil samples will be <br /> collected and submitted for laboratory analysis. Samples will be taken at 10 feet and <br /> 15 feet BGS for each boring, for a total of 4 soil samples per site. Lithologic logging <br /> and field screening by organic vapor analyzer (OVA) will be completed by the <br /> geologist using sampled intervals and soil cuttings. Soil cuttings will be stored onsite <br /> in 55-gallon drums for future disposal. Borings will be grouted with neat cement <br /> slurry (containing less than 5% by weight bentonite powder) upon completion of <br /> drilling activities. The final report will include recommendations for disposal of the <br /> cuttings. <br /> The samples will be screened in the field by the OVA to determine which of the four <br /> samples is to be analyzed. The four samples will then be submitted to Envirotest <br /> (formerly McLaren Analytical Laboratory) under chain-of-custody protocols. The <br /> sample selected in the field will be analyzed specifying a one-week turnaround time, <br /> and the other three will be placed in storage in anticipation of any future analyses. <br /> The selected sample will be analyzed for TPH using EPA Method 8015 (California <br /> Modified). <br /> jw noc'aren <br /> Ht <br /> .. recycled Paper <br />