SITE INFORMATION AND CORRESPONDENCE

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Mr. Harlin Knoll, RENS 2 December 13, 1991 Closure Activities I a On September 30, 1991 Canonie field personnel re-excavated the two "hot spots" identified from tank removal activities. A backhoe was used to excavate the clean backfill to the approximate original excavation limits at the southern end of the former pump island and former tank locations. The native clay soils were then screened with a Photoionization Detector (PID)' for the presence of petroleum hydrocarbons during excavation. The southern end of the former pump island location was then over-excavated to a depth of approximately 14.5 feet below ground surface. Once a field determination was made that the excavation was complete, the backhoe was used to collect a bottom sample i (designated 05S-P-14.5') and a sidewall sample (designated 05S-P-11.5') from the excavation for closure verification. The sample locations and approximate limits of the final excavation are shown on. Figure 1. Ground water was not encountered in either } excavation. ' The former 12,000-gallon tank location was over-excavated in a similar manner to a depth of approximately 16.5 feet. During excavation activities at this location no significant Pp Y 9 � 9 contamination was observed during PID screening or by visual inspection of-the soil removed at the former tank location. A sample was collected from the excavation bottom (designated 05S-T-B16') and from the excavation sidewall (designated 05S-T-W10.5'). Sample locations and approximate excavation limits are again shown on Figure 1. Approximately 50 cubic yards of soil containing petroleum hydrocarbons was excavated and stockpiled at the site. The stockpile was placed on an elevated area of the site to prevent run-on and was covered with plastic sheeting. Two discrete stockpile samples were collected (designated 05S-SP-1 and 05S-SP-2). All soil samples were collected in brass tubes and placed immediately in iced coolers. Samples were picked up at the site by Western Environmental Science and Technology's laboratory personnel. The soil samples were analyzed for TPH-G, and BTEX. Findinas A summary of analytical results for closure is given in Table 2. As shown in the table, the excavation bottom sample from the former tank location indicated the presence of toluene { F at a concentration of 0.055 ppm and xylene at 0.011 ppm and the wall sample indicated �! TPH-G at 0.5 ppm and toluene at 0.056 ppm. At the southern end of the former pump island, the excavation bottom sample and wall sample indicated the presence of toluene �j only at concentrations of 0.0094 ppm and 0.035 ppm, respectively. Certified analytical L reports are included in Attachment A. i CanonteE nv i ronmental a