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_ gas), total lead, EDB and volatile aromatics (BTE&X). TPH as gasoline, benzene, toluene, ethylbenzene and xylene was detected in the water sample collected beneath the 12,000- gallon tank at concentrations of 24 mg/1 (parts per million, ppm), 0.186 ppm, 0.462 ppm, _ 0.101 ppm and 2.754 ppm, respectively. No EDB or lead was detected in this sample. In a letter dated August 30, 1994, the PHS/EHD stated that "due to the shallow depth to groundwater at the site" further investigation would be required. 3.0 PROCEDURES 3.1 Drilling and Sampling On October 21, 1994, one soil boring was drilled at the site. The boring was drilled near the center of the former USTs, and advanced to a depth of 25 feet. The boring was completed as a groundwater monitoring well MW-1 (see Section 3.3). The location of the boring is shown on Figure 2. The boring was drilled using a truck-mounted CME 75-HT drill rig. The drill rig and two- man crew were supplied by Soils Environmental Services (SES) of Benecia, California. Soil samples were collected at five-foot intervals using a split tube sampler loaded with three clean, 2-inch 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 solution and rinsed twice with water prior to each sampling run. For each sample, both ends of the lead tube were covered with aluminum sheets, capped and sealed with tape. The samples were then stored on ice and transported under chain-of- custody to Western Environmental Science & Technology (WEST) in Davis, CA. During drilling, auger returns were monitored for the presence of organic vapors using a photo-ionization detector (PID: Thermo Environmental 580A, 10.0 eV, calibrated to isobutylene). Auger returns were then placed on plastic sheeting and stored on-site. 3.2 Logging Soil was extruded from the second brass tube 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 Log, Appendix A). 6-61.1 Audit Sn rv�o Inc. 4 Pd. M- A—PIERAZI -1994