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7 � . FIELD INVESTIGATION To investigate the extent of residual soil contamination at the site, a total of five soil bonngs were advanced to depths ranging from approximately 6 feet to 46 feet below ground surface (bgs) All field activities were performed in accordance with Smith Technology's Workplan for Subsurface Investigation at 2804E Fremont Street, Stockton, California, dated July 1, 1997 This workplan was approved by PHS/EHD on July 21, 1997 with slight modifications Soil Borings, Soil Sample Collection On July 23, 1997, a Snuth Technology geologist supervised the advancement of five soil borings ranging in depth from 6 to 46 feet bgs A site plan showing soil boring locations is included as Figure 2 Fisch Environmental, California Licensee C57 683865, advanced the borings using a truck mounted Geoprobe® narrow diameter rig employing direct push technology Soil samples were described according to the Unified Soil Classification System Descriptions of soil types encountered and sample collection intervals are presented on boring logs in Attachment 1 Soil samples were collected at five-foot intervals in acetate sampling tubes beginning at four feet below the ground surface Each soil sample was field screened with a Photoionization Detector (PID) for the presence of volatile organic compounds Sample tubes were immediately sealed at each end using Teflon tape and plastic end caps, labeled, and placed on ice pending laboratory analysis Subsequent to sample collection, the soil borings were grouted to the surface with a . neat cement grout Selected soil samples were kept on ice and delivered under chain-of-custody documentation to a State-certified NEUGTEL Environmental Laboratories, Inc for chemical analysis Based on field observations (i a soil types and conditions, odor, discoloration) and discussions with personnel on site at the time of drilling, soil bonngs SBI, SB4 and SB5 were placed in close proximity to the former underground storage tank (UST) pit location Additionally, SB2 was positioned at the suspected location of the former UST dispenser piping adjacent to ballards which once protected the former fuel dispenser Boring S133 was placed in what is believed to be inside the excavated area of the former tank No obvious petroleum hydrocarbons were observed during field activities in the perimeter borings SBI, S132, S134 and SBS PID readings of collected soil samples did not exceed background levels of approximately 0 to 2 parts per million (ppm) However, obvious petroleum odor and elevated PID measurements were noted in soil samples collected from SB3 at depths ranging from 14 to 21 feet bgs and at 44 to 46 feet bgs No obvious petroleum odor or elevated PID readings above 2 ppm were noted in S133 from 24 to 31 feet bgs An attempt was made to advance the Geoprobe unit to approximately 55 feet in order to collect a groundwater grab sample, however probe refusal was encountered at 46 feet bgs, the maximum depth explored during this w investigation i w\97735tireportslsum doe 2 • SMTH