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i 17 June 1996 u AGE-NC Protect No 95-0121 Page 2 of 6 - excavation procedures were described by Kleinfelder in reports dated 22 September 1988 and 14 June 1989 23 SITE ASSESSMENT A total of ten soil borings and nine monitoring wells were installed at the site between May 1989 and December 1994 Nine soil borings (B-1 through B-9) were drilled and sampled in May 1989 by Kleinfelder Hydrocarbons were detected in soil samples from seven of the nine borings In February 1991, Klemfelder drilled and installed monitoring wells MW-I through MW-3 at the site Total petroleum hydrocarbons quantified as gasoline (TPH-g) were detected in ground water samples collected from each well-during the initial sampling event In June 1991, 15 feet of free product was - measured in MW-1 ' In May 1992, three additional ground water monitoring wells were installed at the site (MW-4 through MW-6) by Artesian Environmental Consultants TPH-g was detected in MW-4 and MW-6 at concentrations up to 15,000 parts per billion(ppb) Hydrocarbons were not detected in the sample from MW-5 In December 1994, three monitoring wells (MW-7 to MW-9) and one soil boring were installed as part of the on-going investigation Two wells were installed off-site and one well was installed on- site (see Figure 2) by Geological Audit Services, Inc Petroleum hydrocarbons were detected in 4 of 1 I soil samples analyzed from MW-7 and the boring Petroleum hydrocarbons were not detected in either soil or ground water samples from MW-8 or MW-9 2 4 GROUND WATER DEPTH AND FLOW DIRECTION Depth to the water-table surface beneath the site has fluctuated from approximately 21 feet bsg to approximately 33 feet bsg between 1991 and 1996 -The uppermost ground water flows in an unconfined aquifer Lines of Equal Depth of Water Wells Fall 1993p ublished by the San Joaquin County Flood Control and Water Conservation District indicates that regional ground water flow is towards the northeast i t J t +