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I Mr. Kyle Christie Project 20805-146.006 August 5, 1996 Page 5 1 Native soil exposed along the excavation sidewalis was stained in the vicinity of the ' product piping in the northwest and southwest corners of the UST excavation and along the southern and eastern sidewalls'adjacent to the former location.of the 10,000-gallon UST. A continuous stained soil horizon was observed at approximately 10 feet bgs adjacent to the former 10,000-gallon UST location. The native soil underlying the former UST complex was stained gray to-a total depth of approximately 15 feet bgs. SOIL SAMPLING On February 8, 1996, EMCON collected sail samples from the UST excavation and piping trenches in accordance with the "Tri-Regional Board Staff Recommendations for Preliminary Evaluation and Investigation of Underground Tank Sites" (August 1992). Soil sample locations are shown on Figure 3. The SJCPHS observed the soil sampling activities. in order to define the 1vertical 1.'extent of petroleum hydrocarbon-impacted soil, ACES excavated a total of six "potholes" to depths of 19 to 23 feet bgs in the former UST complex. These depths correspond to depths of 7 to I 1 feet below the native soil and.fill material contact. Visual evidence of impact in the form of staining was observed to depths I of approximately 15 feet bgs. EMCON personnel field screened the excavated soil using a portable photoionization detector (PID) to monitor impacts. Moderate to strong petroleum hydrocarbon odors were present-in the soil extending to the total depth excavated. A total of six soil samples (TS-1 through TS-6), one soil sample from the base of each pothole, were collected (see Figure 3). EMCON personnel collected soil from the excavator bucket by removing 3 to 6 inches of soil and driving a brass sample tube into the remaining soil. The sample tube was sealed with Teflon" tape and plastic end caps, labeled, and placed,in a cooler for transport to a state-certified analytical laboratory with chain-of- custody documentation. Soil underlying and adjacent to the.former product line trenches and dispensers consisted of dark grayish brown silt to depths of approximately 3 to 4-feet bgs and brown silt to the total depth explored. Moderate to strong- petroleum hydrocarbon odors were present. Local petroleum hydrocarbon seepage was observed along the base of pea gravel filled piping trenches. Three soil samples (P-1 through P-3) were collected from native soil underlying the piping I trenches at 20 linear foot spacing and at depths of 6 to 9 feet below grade (see Figure 3). Sampling procedures were consistent with those described above. SACNN:\PJM805\08051450.61)S-15�cjb:3