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using geophysical techniques. Instruments employed during the geophysical clearance included a magnetometer, active/passive electromagnetic receivers, and a sonic locator. All identified utilities were marked with pink paint, to signify a temporary survey, and coded with abbreviations to indicate the type of utility. If a buried utility was found within five feet of a proposed boring location, the boring was relocated to a more suitable position. Underground Service Alert (USA) was notified of the subsurface investigation at least 48 hours prior to initiation of intrusive field activities. USA contacted all utility owners of record within the Site vicinity and notified them of Parsons' intention to conduct subsurface investigations in proximity to buried utilities. As a final precaution, each boring was hand augered to five feet bgs. Since the diameter of the hand auger is greater than the diameter of the drilling equipment and utilities are typically buried in the upper two to three feet bgs, hand augering provided an increased level of security. 3.2.2 Soil Sampling Procedures Soil samples were obtained using either truck-mounted PowerProbeTM system or a hand auger. The PowerProbeTM system, provided and operated by Woodward Drilling (C57# 710079), is a push-probe system driven by a hydraulic hammer, which advances a drive sampler lined with clear polyvinyl chloride (PVC) sleeves within steel rods. Upon removal from the subsurface, a four-foot length soil-filled liner was removed from the steel rod and cut open to expose the soil for logging and sample collection. For samples collected with a hand auger, the soil was collected from the bucket of the hand auger for logging and sampling. Hand auger samples were collected in the upper five feet bgs of each boring as the boring was being cleared for underground utilities. For borings that only extended to five feet bgs, hand augering was the only sampling technique used. For those borings that extended past five feet bgs, the PowerProbeTM system was used. Soil samples were collected and placed in pre-cleaned eight ounce glass jars with Teflon-lined lids. The jars were labeled, sealed in plastic bags, and immediately placed in an ice-cooled chest for delivery to a state-certified laboratory. Discrete soil samples were collected from depths of approximately one, three, five, and eight feet bgs, which is the approximate location of groundwater at this Site. Additional samples were collected at depth intervals that displayed potential MGP-related impacts, areas where previous investigations identified MGP related impacts at depth, and/or where the installation of a groundwater monitoring well was required. Soil samples for VOC analysis were obtained from PVC liners or from the bottom of the hand auger bucket immediately after extraction from the boring. In accordance with the Cal/EPA soil sampling guidance document, field coring devices such as disposable Encore 5-gram samplers (Encore"), were used in triplicate to collect each sample. Each filled Encore was placed in individual, resealable plastic bags and placed on ice immediately after collection. Soil from each boring location was classified in accordance with the Unified Soils Classification System and for the presence of staining and/or odor. Remaining soil from sample depths was placed in a sealable bag for headspace gas measurements. The headspace gas for each sample was measured for VOCs using a photoionization detector (PID). Soil classifications and headspace gas measurements are indicated on boring logs provided in Appendix E. The field forms generated during this investigation are provided in Appendix F. PARSONS 20 FINAL RI REPORT-FORMER TRACY MGP APRIL 2010