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ASSOCIATEC Vq V TC S INC contained detectable concentrations of MTBE, and soil samples from S133 also contained detectable concentrations of benzene, ethylbenzene, and xylenes Groundwater samples collected from SB3 and SB4 contained detectable concentrations of TPHg, total petroleum hydrocarbons as diesel (TPHd) and MTBE The groundwater sample from boring S133 also contained detectable concentrations of benzene, ethylbenzene, and xylenes In January 2004, ATC personnel supervised the advancement of soil borings MW1, MW2, and MW3 at the site to depths of approximately 65 feet bgs to evaluate groundwater for the presence of petroleum hydrocarbons and to determine the gradient direction and magnitude The borings were completed as monitoring wells Petroleum hydrocarbons were not detected in the groundwater samples collected from wells MW1, MW2, or MW3 Field activities and analytical results are detailed in ATC's Summary Report of Subsurface .Investigation, dated June 24, 2004 GROUNDWATER ELEVATION r Water level measurements were collected from wells MWI through MW3 on April 12, 2004 Water elevations ranged from a high of —33 70 to a low of —33 92 representing an average increase in water table elevation of 0 65 feet since January 2004 The water level data were used to develop a groundwater elevation contour map (figure 3) Review of the groundwater elevation contour map (Figure 3) indicates that the hydraulic gradient beneath the site on April 12, 2004 was 0 001 feet per foot (or approximately 5 4 feet per mile) and the gradient direction was to the southwest A summary of groundwater monitoring data 1s presented in Table 1 SAMPLING ACTIVITIES On April 12, 2004, groundwater samples were collected by ATC personnel from monitoring wells MW1 through MW3 The locations of the monitoring wells are shown on Figure 2 Prior to collection of the groundwater samples, the depth to water was measured and pH, electrical conductivity, and temperature were recorded for groundwater purged from each monitoring well A minimum of three well casing volumes was purged from each well prior to sampling The wells were allowed to recover and a sample was collected from each well using a disposable bailer Groundwater well purge and sample logs are contained in Attachment I The groundwater samples collected from the wells were submitted to State certified Argon Laboratories (ELAP Cert No 2359) for chemical analyses of TPHg and TPHd utilizing EPA Method 801513, BTEX utilizing EPA Method 8021B, and oxygenate fuel additives including methyl tert-butyl ether (MTBE) utilizing EPA Method 8260B i,2..D GR w-o s r o� ,-,C-L L ANALYTICAL RESULTS 4�or Groundwater samples collected from wells MW1, MW2, and MW3 did not contain concentrations of TPHg, TPHd, BTEX constituents, or fuel oxygenates at or above the laboratory • reporting limits Analytical results for groundwater samples are summarized in Table 2 Laboratory data sheets and chain-of-custody documentation are contained in Attachment 2 w 12687412QR-2404 doe