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Boring Clearance <br /> Multiple subsurface utility pipelines may intersect the project area. Plant drawings will be <br /> reviewed to identify the approximate locations of the underground.services and the nearby <br /> UST's. In addition, a geophysical .survey will be conducted to trace the utility locations and <br /> estimate burial depths. Outlines of utilities will be marked using electro-magnetic detectors <br /> C (EM) and ground-penetrating radar(GPR). Information derived from the geophysical survey can <br /> then be used to mark boring locations. <br /> Drilling <br /> The soil borings will be completed using a truck-mounted drill rig with hollow-stem augers. <br /> Undisturbed soil samples are collected by driving a split spoon sampler past the bottom of the <br /> augers. Following completion of each borehole, a bentonite or concrete slurry will be used as <br /> backfill. All drill cuttings - <br /> and non retained samples will be placed in 55-gallon drums. The <br /> decontamination and steam-cleaning water will also be stored in 55-gallon drums. The drums <br /> will be stored on site pending characterization for proper disposal. <br /> Soil Sampling <br /> During the completion of each boring, soil samples for laboratory analysis will be collected at 5- <br /> foot depth intervals beginning at 5 feet bgs to the maximum depth of the boring. Each sample <br /> will be collected using a.California split spoon sampler fitted with stainless steel liners. The <br /> sampler will be driven into the .soil in front of the drill bit t collect p o o ect undisturbed samples. <br /> Generally, four samples from each depth interval .will be collected; one for laboratory analysis, <br /> one for on-site field screening (headspace analysis) and two for geological observation and <br /> potential archiving. Headspace analysis will be performed using a Flame Ionization Detector or.a <br /> Photo Ionization Detector. <br /> Preparation of samples for analysis will involve first covering both ends of the filled stainless <br /> steel liner with teflon sheets, and then sealing with plastic end caps. The samples will then <br /> appropriately be labelled and placed in a cooler with "Blue Ice". Sample identification numbers <br /> will be recorded on a Chain-of-Custody form. <br /> L <br /> TETRA TECH:Stockton Developmental Center,Revised Site Investigation Work Plan Page 8 <br /> i..i' <br />