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C- vvAT c A s s o c i n r e s i ru c on September 28, 1998 the well was developed and sampled Analytical data indicated that soil and groundwater samples contained detectable concentrations of petroleum hydrocarbons Field activities and analytical results were detailed in ATC's Summary Report of Additional Subsurface Investigation, dated January 8, 1999 In December 1999, ATC personnel supervised the advancement of soil borings MM2, MW3, and MW4 at the site to depths of approximately 65 feet bgs to evaluate groundwater for the presence of petroleum hydrocarbons and determine the gradient direction and magnitude The borings were completed as groundwater momtonng wells Analytical data indicated that soil samples from boring MW2 contained detectable concentrations of petroleum hydrocarbons Petroleum hydrocarbons were also detected in the groundwater from well MW2 Well MW3 contained very low concentrations of only a few constituents and well MW4 was nondetect Field activities and analytical results were detailed in ATC's Summary Report of Additional Subsurface Investigation, dated February 24, 2000 GROUNDWATER ELEVATION Water level measurements were collected from wells MW 1 through MM4 on June 22, 2000 Water levels ranged from 45 14 to 45 45 feet below the tops of the well casing elevations . representing an average increase m the water table elevation of approximately 0 50 feet since April 2000 The water level data were used to develop the groundwater elevation contour map (Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed generally towards the southwest with a northwest component The average hydraulic gradient on June 22, 2000 was calculated to be 0 001 ft/ft or approximately 7 ft/mile A summary of groundwater monitoring data is presented in Table 1 SAMPLING ACTIVITIES On June 22, 2000, groundwater samples were collected by ATC personnel from monitoring wells MWl through MW4 The locations of the monitoring wells are shown on Figure 2 Prior to collection of the groundwater samples, the depth to water, pH, electrical conductivity, and temperature were measured in each monitoring well and recorded A mimmum 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 dedicated disposable bailer Groundwater well purge and sample logs are contained in Attachment 1 The groundwater samples collected from the wells were submitted to State-certified Sequoia Analytical (FLAP Cert No 1624) for chemical analysis of total petroleum hydrocarbons as gasoline (TPHg), total petroleum hydrocarbons as diesel (TPHd), total petroleum hydrocarbons as kerosene (TPHk), benzene, toluene, ethylbenzene, and xylenes (BTEX)utilizing EPA 8015 and 5020 methodologies, and oxygenate fuel additives mcludmg methyl tertiary butyl ether (MTBE) • utilizing EPA 8260 methodology w\62577VgxvU\2n&20W dw 2