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Z M1 S + i 05 April 1996 AGE-NC Project No 95-0111 Page 2 of 6 Prior to March 1996, ground water samples had been collected on three occasions from each well at the site The depth to ground water at the site is approximately 6 feet, with-a prevailing flow ' direction toward the north to northeast ' 3.0. PROCEDURES 3 1 DRILLING AND SAMPLING ' On 26 February 1996, two borings were drilled at the site to a depth of 15 feet below surface grade (bsg) and completed as ground water monitoring wells MW-5 and MW-6 Well MW-4 was over- drilled, then the casing, filter, pack, bentornte`plug and grout seal were replaced All drilling was performed using a truck-mounted CME 75-HT drill rig equipped with 8 25-inch ' diameter hollow-stem augers The drill rig and two-man crew were supplied by Soil Exploration Services (SES) of Benicia, California The locations of the borings are shown on Figure 2 Samples were collected at five-foot intervals in each boring using a split tube sampler loaded with three clean, 2 by 6-inch brass sleeves A 140-pound hammer was used to advance the sampler 18 inches, the number of blows required to advance the sampler in 6-inch increments was recorded on ' the boring logs All sampling equipment was washed in an Alconox solufion and rinsed twice with water prior to each sampling run ' For each sample, both ends of the leading sleeve were covered with Teflon sheets, capped and sealed with tape The samples were stored in a chilled container and transported under chain-of-custody to ' McCampbell Analytical, Inc (MAI) in Pacheco, California Each sample was analyzed for total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d) and volatile aromatics (benzene, toluene, ethyl benzene and xylenes BTE&X) in accordance with EPA methods ' 5030/8015m and 602, respectively During drilling, auger returns were monitored for the presence of organic vapors using a photo- ionization detector (FID Thermo Environmental 580A, 10 0 eV, calibrated to isobutylene) Auger returns were then placed on plastic sheeting and stored on-site pending laboratory analysis I3 2 LOGGING Soil was extruded from the second brass sleeve and screened for the presence of organic vapors, using a PID, and the readings were recorded on the boring logs The soil was then described in accordance with the Unified Soil Classification System (see Boring Logs, Appendix A)