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Working To Restore Nature 11 Subsequent to excavation activities, the pit was backfilled with imported fill material in accordance with local agency requirements Analytical Results No analytes were detected in confirmation samples from the excavation pit with the exception of sample EX -WWI -9' which contained 0 0098 ppm xylenes, sample EXEW 1-9' which contained 3 2 ppm TPHd, and sample EXEW2-9' which was reported to contain benzene (0 070 ppm), toluene (0 043 ppm), ethylbenzene (0 085 ppm), xylenes (0 33 ppm), TPHg (35 ppm) and TPHd (430 ppm) Analytical results are summarized in Table 2 The water sample collected from the pit by bailer was reported to contain 410 ppb TPHd, 140 ppb TPHg, 0 70 ppb toluene, 3 1 ppb ethylbenzene, and 1 i ppb xylenes These results are summarized in Table 4 Analytical results of composite soil samples collected from the stockpiled soil detected low to moderate levels of petroleum hydrocarbons Laboratory data sheets and chain -of -custody documentation are presented in Attachment 2 . CONCLUSIONS/RECOMMENDATIONS Soils Field observations and analytical data indicate that vertical migration of contamination has not occurred beyond 14 feet below surface grade and that lateral migration was not extensive Previously collected analytical data indicated that the main area of concern was the soil in the vicinity of the former diesel fuel tank pit Analytical results of excavation confirmation samples indicate that all impacted soil has been removed, with the exception of a zone that was observed between approximately 6 and 11 feet below grade directly beneath the budding on the east wall of the pit and continuing to the east for an unknown distance The location of sample EXWW1-9', which was reported to contain 0 0098 ppm xylenes, may have been removed during subsequent excavation of a thin zone of discoloration along the west wail Figure 4 shows the estimated extent of contaminated soil that remains beneath the building Assuming that this zone is uniformly 4 feet thick, approximately 75 cubic yards of impacted soil remain Of this total, only 5 to 10 cubic yards contain petroleum hydrocarbons between 100 and 430 ppm, 15 to 20 cubic yards contain between 10 and 100 ppm hydrocarbons, and 50 cubic yards contain less than 10 ppm petroleum hydrocarbons The volume of diesel in the soil was calculated by determining the value of TPHd concentrations for each interval shown in Figure 4 and assuming an average TPHd concentration for each interval Approximately 7 5 pounds (1 1 gallons) of diesel is estimated to remain in the soil ,0 SXR1293 URF 4