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14 August 1991 GeoAudit CV 43C5-1.3 Page 2 of 4 ionization detector (PID) was used to monitor contamination levels during excavation. The excavated soil was stockpiled adjacent to the tank cavity and coverel with plastic. One soil sample (GOT1-9) from a depth of approximai.ely 9 feet was preserved in a brass sleeve and relinquished to a state-certified laboratory for analysis of aquatic toxicity. An excavator was used to deepen the excavation to 21 feet on 27 June and a backhoe was used to enlarge it slightly on 16 July. Soil samples were collected on both days. Sample MCT-1 was collected from the bottom of the excavation. Sidewall samples MCSW-1, MCSW-2, MCSW-3, and MCSW-4 were collected from the excavation wails at a depth of approximately 15 ft below grade (Figure 2) . The backhoe was used to excavate soil from the sidewalls, and a slide hammer w loaded with two 2-inch brass tubes was used to collect samples from the backhoe bucket. Stockpile samples MCSP-1A and B and MCSP-2A, B, C, and D were collected by slide hammer from the soil piles. Samples were covered with aluminum foil, capped, sealed with duct l tape, and placed on ice until transport to WEST, Inc. for laboratory analysis. Samples were analyzed for gasoline, diesel, motor oil, and BTE&X (EPA methods 8015 and 8020) , chlorinated hydrocarbons (EPA method 8410) , PCB's (EPA method 8270) , and five metals (Cr, Cd, Pb, Zn, and Ni) . f + The northwest corner of the excavation was enlarged on 2 August 1991 because residual contamination was detected in sample MCSW-1- from that portion of the cavity. After reexcavation, sample MCSW-5 was taken by excavator from a depth of approximately 22 feet (Figure 2) . ?INDXNGG Copies of laboratory results and chains of custody for all samples are attached. The results are discussed briefly below. A dark gray gravelly clay layer, containing bits of pipe and other man-made material, was present in the upper three feet of the excavation. This layer is backfill material. A layer of yellow silty fine-to-very-fine-grained sand extends from 3 feet to 13.5 feet. PID readings of soil samples betweeen 8 ft and 14 ft below grade ranged between 250 and 500 ppm. The top of a relatively dense, hard clay bed was encountered at 13 .5 feet. The base of this layer was difficult to identify, but r appeared to be approximately 20 feet. ll Laboratory analyses confirm the field observations that contamination was present in the tank cavity. Sidewall samples