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CvvATc A S S O C L A T E S E !V C 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 boirngs MW2, 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 monitoring 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 Groundwater from 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 In December 2001, soil-boring VEW1 was advanced to approximately 35 feet bgs, and borings VEW2 and VEW3 were advanced to approximately 45 feet bgs Borings MW5, MW6, and MW7 were advanced to approximately 65 feet bgs Soil borings VEWI, VEW2, and VEW3 were completed as 2-inch diameter vapor extraction wells and soil borings MW5, MW6, and MW7 were completed as 2-:rich diameter groundwater monitoring wells Boring CPTI was advanced to approximately 100 feet bgs utilizing a truck-mounted CPT rig A soil vapor extraction pilot test was conducted which yielded a radius of influence (ROI) of approximately 30 feet Approximately 2 64 pounds of total petroleum hydrocarbons as gasoline (TPHg), • benzene, toluene, ethylbenzene, and xylenes (BTEX) were removed during the vapor extraction pilot test Soil vapor extraction appeared to be a viable method for remediating TPHg and BTEX impacted soil at the site Field activities and analytical results were detailed m ATC's Remedial Investigation/Feasibility Study, dated October 21, 2002 GROUNDWATER ELEVATION Water level measurements were collected from wells MW I through MW7 on January 23, 2003 Water elevations ranged from a high of —30 96 to a low of —3104 representing an average increase in water table elevation of 0 98 feet since October 2002 The water level data were used to develop the groundwater elevation contour map (Figure 3) Review of the groundwater elevation contour map (Figure 3) indicates that the hydraulic gradient beneath the site on January 23, 2003 is relatively flat and the gradient varies across the site A summary of groundwater monitoring data is presented in Table I SAMPLING ACTIVITIES On January 23, 2003, groundwater samples were collected by ATC personnel from monitoring wells MWI through MW7 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 minimum of three well casing volumes was purged from each well prior to sampling The wells were allowed to recover w lwordpro162577UQR-2003 doc 2