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I 1 3.4.5 Purge Water Disposition Purge water from monitoring wells at the Site was stored in 55-gallon DOT drums Purge water from the March and June 1993 monitoring events was disposed on-site The water was placed on the stockpiled soil. This soil was then disposed at a licensed landfill facility (see Section 3 5 4) Since purge water from all subsequent monitoring events was uncontaminated, the containerized water was discharged on-site 3.5 Excavation Activities The contaminated soil was excavated from the UST site in two phases because of space limitations and equipment capabilities The first phase of excavation was performed on August 30 and 31, 1993 The second phase of excavation was performed on September 21, 1993 After each phase of digging, soil samples were collected from the floor and sidewalls of the excavation The excavator and operator were provided by Ned Pepper, Inc of Folsom Full documentation of the excavation activities is presented in the Preliminary Investigation and Evaluation Report (PIER), dated April 5, 1993, prepared by GeoAudit During both phases of excavation, a total of 15 samples were collected from the sidewalls and floor of the excavation All samples were collected at the direction of Ms Mary Meays of the PHS/EHD As the excavation proceeded, the soil was screened for the presence of organic vapors using a photo-minzation detector (PID Thermo Environmental 580A, 10 0 , eV, calibrated to isobutylene) and segregated into contaminated and clean stockpiles Analytical results of soil samples collected during excavation activities are presented in Table 6 3.5.1 Phase I Excavation August 30 - 31 1993 g � Soil was excavated to a depth of 30 feet, removing approximately 1,000 cubic yards of soil from the former UST site Most of the soil samples collected were uncontaminated, however, one sample from the floor (sample BI-32) and two samples from the west wall (samples W-26 and W-29)contained trace concentrations of petroleum hydrocarbons (Table 3) 3.5.2 Phase II Excavation, September 21, 1993 During the second phase, the excavation was deepened to a total depth of 39 feet No petroleum hydrocarbons were detected in soil samples collected from the west wall of the excavation during this phase Only sample 135-39, collected from the floor of the excavation at a depth of 39 feet, had any detectable hydrocarbons Benzene and toluene were detected at 0 006 ppm and 0 007 ppm, respectively The detected levels of benzene and toluene are slightly above the 0 005 ppm detection limits for these compounds 9 w aiQnnsv4+