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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 covered with plastic. One soil sample (GOTI-9) from d depth of approximately 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. Snll samples were coll-cted on both days. Sample MCT-1 was collected from the bottom of the excavation. SYdewall samples MCSW-1, MCSW--2, MCSW-3, and MCSW-4 were collected from the excavation walls 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 loaded with two 2-inch brass tubes was used to collect samples from the backhoe bucket. Stockp?le samples MCSP--_A and B and MCSP-2A, B, C, and D were collected by slide hammer from the soil piles. Samples were covered with aluminum foil, tape, and capped, sealed With duct placed on .ice until transport to WEST, Inc. for laboratory analysis. Samples were analyzed for gasoline, diesel, motor 011, and BTE&X (EPA methods 8015 and 8020) ,., hydrocarbons (EPA method 8010) , PCB's ,EPA method 8270) , and five metals (Cr, Cd, Pb, Zn, and Ni) . and five t The northwest corner of the ex^avation 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) . FXNDINGS Copies of laboratory results and chains of custody for all samples are attached. The results are discussed briefly below. x� 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 SO11 samples betweeen 8 ft and 14 f below �W grade ranged between 250 and 500 ppm. The top of a relatively dense, hard clay bed was encountered at OL 13 . 5 feet. The base of this layer was difficult to identify, but appeared to be approximately 20 feet. Laboratory analyses confirm the field observations that contamination was present in the tank cavity. Szdewall samples