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1 3.0 PROCEDURES 3.1 Purge Procedures ' Monitoring was conducted on January 3, 1994 A Solznst water level meter was used to measure the depth to water in the three monitoring wells The standing water was ' purged using a three-stage purge pump Water samples were collected after 18 to 24 gallons (approximately three well volumes) of water had been removed and temperature, pH and conductivity of the groundwater had stabilized (Table 3) These parameters were tmeasured at two-gallon intervals using a Hydac water analyzer The water was stored on- site in DOT approved drums ' 3.2 Sample Collection ' Water samples were collected using a disposable plastic bailer Three 40-m1 EPA vials and one 1-liter amber bottle of water were collected from each well and transported in a chilled container to WEST Laboratories in Davis ' 3.3 Drilling and Sampling Drilling of the additional assessment borings was performed on January 21, 1994 The truck-mounted drill ng equipped with 8-inch-diameter hollow-stein augers was provided by V&W Drilling of Rio Vista, California A 140-pound hammer was used to advance ' the split-spoon sampler loaded with three brass sleeves, and the number of blows required to advance the sampler 18 inches was recorded on the boring log (see Appendix A) To avoid cross contamination, the sampling equipment was washed in a tri-sodium ' phosphate (TSP) solution and rinsed twice with water prior to each sampling run Boring 134 was located 5 feet north of monitoring well MW-2, on a small promontory in ' the south wall of the previously excavated tank cavity (Figure 3) In accordance with the PHS/EHD directive dated November 12, 1993 and GeoAudit's interim work plan dated January 3, 1994, B4 was drilled to a depth of 20 feet and samples were collected at 12 5, 15, 17 5, and 20 feet Boring B5 was located 10 feet southeast of MW-2, and sampled at the same depths The purpose of both borings was to define the extent of soil contamination previously encountered between 15 and 20 feet below surface grade Although no evidence of soil contamination was noted in samples collected at these depths, hydrocarbon odors and oil-staining were observed in soil cuttings from B4 between approximately 4 and b feet Therefore, Ms Mary Meays of PHS/EHD recommended that two additional borings be drilled so that samples could be collected above 10 feet Upon approval from Mr John Uruttia of the Bank of Stockton, borings B4A and BSA were drilled in close proximity to B4 and B5, and samples were collected at 5, 7-1/2, and 10 feet in B4A and at 3-1/2 and 5 feet in BSA 7 I