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4.3 Drilling <br /> LThe soil boring program.was implemented on February 3, 1995. SJPHS officials were <br /> notified in advance of the scheduled investigation activities to coordinate appropriate <br /> Linspections. Photo-documentation of the drilling program is presented in Appendix A. <br /> LThe soil borings were completed using a truck-mounted drill rig with eight inch diameter <br /> hollow-stem augers. Undisturbed soil samples were collected by driving a split spoon sampler <br /> L past the bottom of the augers that had been advanced to the sampling depth. Following <br /> completion of each borehole, a bentonite or concrete slurry was used as backfill. All drill <br /> cuttings and non-retained samples were placed in 55-gallon drums. Decontamination and <br /> Lsteam-cleaning water was also stored in 55-gallon drums. The drums were stored on site <br /> pending characterization for proper disposal. <br /> L <br /> 4.4 Borehole Soil Sampling <br /> LOne soil sample was collected from each boring at the 9-foot depth interval for <br /> geological <br /> observation, on-site screening and laboratory analyses. The soil samples were collected from <br /> LM� beneath the former UST to determine if petroleum hydrocarbons had discharged from the tank. <br /> L4.4.1 Soil Sampling Methodology <br /> LAll soil samples were collected using a modified California split spoon sampler fitted with <br /> stainless steel liners. The sampler was driven into the soil in front of the drill bit to collect <br /> } reasonably undisturbed samples. Two samples from each interval were retained; one for <br /> j� laboratory analysis and one for soil description and on-site screening. Preparation of samples <br /> for laboratory analysis involved first covering both ends of the filled sleeve with aluminum <br /> L foil, and then sealing the sleeves with plastic caps. The samples were then appropriately <br /> labelled and placed in a cooler on blue ice pending shipment to the laboratory. Sample <br /> Lidentification numbers were recorded on Chain-of- Custody forms. <br /> L4.4.2 Field Monitoring for Volatile Org nicomnoun s, <br /> One soil sample was collected from each boring for on-site field screening for volatile organic <br /> compounds. The field monitoring of the samples was conducted using a Microtip <br /> Liw photoionization detector (PID). Prior to field use, the PID was calibrated and bench-tested. <br /> LTETRA TECH:Castle Rock Forest Fire Station,Preliminary Site Assessment Repoli Page 10 <br />