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C,.,VAT A S S O C I A T E S I N C k• x 2.1 Drillin-a Activities From November 28 to November 30, 2001, an ATC geologist supervised the advancement of eight soil borings, SBI through SB8. Due to delays in obtaining access agreements, soil boring SB9 was advanced on January 14, 2002. A site plan with soil borings locations is shown on .Figure 2. Soil borings.SB 1 and SB2 were advanced near Vaults 7 and 8 on the north site of the processing plant. Soil boring SB3 was advanced near Vault 5 on the east site of the site. Soil borings SB4 and SB6 were advanced on either side of Vault 1, located on the southeast part of the site. Soil boring SB5 was advanced near Vault 6 near the southeast corner of the processing plant. Soil F borings SB7 and SB8 were advanced near the City of Stockton municipal well and water tower at the northeast portion of the site. Soil boring SB9 was advanced off site on the north side of East Worth Street, approximately 200 feet north of Vaults 7 and 8. FSoil borings SB 1 through SB9 were advanced to depths of approximately 56 to 60 feet bgs to the first encountered groundwater. The depth to water ranged from approximately 51 to 57 feet bgs. Due to the high density of the soil encountered at the site the number of samples collected was less than originally estimated. Soil samples were collected at five-foot intervals to depths of 21 to 25 feet bgs and then at 40 feet bgs. The soil probing unit was further advanced to depths of 56 to 60 feet bgs in order to collect a groundwater sample. Descriptions of soil types encountered, field observations, and sample collection intervals are Fpresented on the soil boring logs contained in Appendix B. E 2_2 Soil Matrix Sample Anal s Sample tubes were capped at each end using Teflon tape and plastic end caps, and labeled, and 4 stored in a cooler with ice. Selected soil samples from the borings were delivered under chain- of-custody protocol to State-certified Argon Laboratories (ELAP Cert. No. 2359) for chemical analysis. kF Soil matrix samples from borings SBI through SB9 were analyzed for chromium VI by EPA Method 7199. FCopies of the analytical reports and chain of custody documentation are included in Appendix C. F223 Groundwater Matrix Sam le Analysis One groundwater sample each was collected from borings SBI through SB9 at the depth groundwater was first encountered, approximately 51 to 57 feet bgs. A Geoprobe® Screen Point r 15 Groundwater Sampler was threaded onto the leading end of the Geoprobe after groundwater had been encountered. When the sampler was advanced, O-ring seals and an expendable drive point provided a watertight system to ensure sample integrity. I Fw:lwordpro162583\reports\Subsurf report.duo 3