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1 <br />' 11 November 1999 <br /> • AGE-NC Project No 97-0230 <br />' Page 3 of 7 <br />' 2 4 GROUND WATER DEPTH AND GRADIENT <br /> Based on review of the Lines of Equal Depth to Groundwater Fall 1997 map published by the San <br />' Joaquin County Flood Control District and Water Conservation District(FCD&WCD),the estimated <br /> depth to ground water at the site is approximately 50 feet below surface grade (bsg) Review of the <br /> map Lines of Equal Elevation of Groundwater Fall 1997(FCD&WCD) depicts the regional ground <br />' water flow direction towards the northeast <br />' 3.0. PROCEDURES <br /> On 31 August 1999, six soil probe borings (P-1 through P-6) were advanced at the site as part of <br /> assessment activities related to the three former USTs The field work was conducted as outlined in <br /> the PHS-EHD-approved work plan dated 06 August 1999 <br /> 3 1 DRILLING ACTIVITIES <br /> lie Soil probe borings P-1 through P-6 were advanced utilizing a van-mounted Geoprobe 5400 equipped <br /> with 1 125-inch diameter probe rods with an attached 2 15-inch diameter soil sampler, using "direct <br />' push"technology Soil probe boring P-3 was advanced vertically to a depth of 35 feet bsg, P-1, P-2, <br /> P-4, P-5 and P-6 were advanced to 30 feet bsg (See Figure 2) <br />' <br /> 3 1 1 Soil Sample Collection <br />' Discrete soil samples were collected at 5-foot intervals,beginning at 5 foot bsg,to total depth of each <br /> boring Soil samples were collected using a Geoprobe soil sampling assembly loaded with four pre- <br /> cleaned 1 125-inch by 6-inch brass sleeves Soil samples were preserved by covering both ends of <br /> the brass sleeve with Teflon sheets, capping, and sealing with tape Each sample sleeve was labeled <br /> with soil probe boring location, depth, time, date and sampler's initials <br />' Each preserved sample was logged on a chain-of-custody form, placed in a chilled container and <br /> transported to a California Department of Health Services (DHS)-certified laboratory under chain <br /> Lof custody, selected samples were analyzed for <br />' • TPH-g, TPH-d, TPH-mo by EPA Method 3540/5030/8015M, <br /> . • BTEX and MTBE by EPA Method 8020, and <br /> • Tertiary butanol (TBA), di-isopropyl ether (DIPS), ethyl tert butyl ether (ETBE) and tert <br /> Advanced GeoEnvironmental,Inc <br />