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ASSH ,9 O C I ATE S I N C . detected in the groundwater sample collected from soil boring SB 1. The January 1998 subsurface investigation results are detailed in ATC's Summary Report for Subsurface Investigation, dated February 4, 1998. In September 1998, ATC supervised the excavation of approximately 70 tons of impacted soil. The soil was transported and disposed of at an appropriate landfill on the same day it was excavated. The excavation was limited on two sides by buildings and overhead lines. Confirmation samples collected from the excavation indicated there was residual contamination remaining. Also in September 1998, ATC supervised the advancement of four soil borings around the former excavation area. Three of the borings were completed as groundwater monitoring wells. Analytical data indicated the soil and groundwater at the site is impacted with total petroleum hydrocarbons as stoddard solvents (TPHss). The September 1998 subsurface investigation results are detailed in ATC's Summary Report of Soil Excavation and Additional Subsurface Investigation, dated December 3, 1998. SAMPLING ACTIVITIES On March 29, 1999, groundwater samples were collected by ATC Associates personnel from monitoring wells MW1 through MW3. The locations of the monitoring wells are shown on Figure 2. Prior to collection of groundwater samples, the depth to water, pH, electrical • conductivity, and temperature were measured in the monitoring wells and recorded. A minimum of three well casing volumes were purged from each well prior to sampling. The wells were allowed to recover and samples were collected from each well using dedicated disposable bailers. The groundwater samples collected from each well were submitted to State-certified Sequoia Analytical (ELAP Cert. No. 12 10) for chemical analysis of total petroleum hydrocarbons as gasoline (TPHg), total petroleum hydrocarbons as diesel (TPHd), and (TPHss) utilizing EPA methods 8015 ]modified, and benzene, toluene, ethylbenzene, and xylenes (BTEX) utilizing EPA methods 8020. Groundwater well purge and sample logs are contained in Attachment 1. ANALYTICAL RESULTS The groundwater sample collected from well MW1 contained TPHd and TPHss at 95 micrograms per liter (ppb) and 52 ppb, respectively. The groundwater sample collected from well MW2 contained TPHd at 77 ppb. The groundwater samples collected from wells MW1 and MW2 contained no detectable concentrations of TPHg or BTEX. The groundwater sample collected from well MW3 contained TPHg and TPHd at concentrations of 6,840 ppb and 9,000 ppb, respectively. The groundwater sample from well MW3 also contained TPHss at a concentration of 16,000 ppb and detectable concentrations of ethylbenzene and xylenes. The detection levels for benzene and toluene were elevated due to dilution factors. The groundwater samples from wells MW1 through MW3 contained detectable concentrations of TPHd, but the chromatogram pattern did not match the pattern for diesel. Analytical results of groundwater w:1172951quan1yl4gr-i998.doc 2