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� v A S S O C I A T E S I N C hydrocarbons remaining in soil is approximately 2,606 kilograms or 5,733 pounds Mass balance calculations are contained in Appendix C and Figures used to calculate areas of impacted soil are ' also contained in Appendix C ' 42 Groundwater Conditions 4 2 1 Site Hydrogeology From January 1994 to November 2003, static water levels have fluctuated from approximately 8 85 to 22 9 feet bgs in groundwater monitoring wells MW1 through MW7 and vapor extraction ' wells VE1 and VE6 Depth to water levels has been observed to fluctuate, however, there has been an overall decrease in depth of water of approximately 12 feet from January 1994 to November 2003 The most recent quarterly monitoring was performed by AGE in November ' 2003 During this period, groundwater was measured at depths ranging from 13 65 to 17 19 feet bgs Since 1994, groundwater flow direction has been calculated to be predominantly towards the northeast and southeast Groundwater flow directions towards the northwest and' southwest have also been calculated However, laboratory analytical data from soil and groundwater samples indicate that petroleum hydrocarbons have been transported from the former UST location towards a southwest direction Hydrologic gradients of 0 003 to 0 0125 ft/ft have been calculated at the site Figure 3 shows a groundwater contour map generated from the November 2003 data, ' groundwater elevation measurements are presented in Table 5 4 2 2 Petroleum Hydrocarbons in Groundwater Groundwater monitoring well MWI has been sampled since December 1990 wells MW2 , MW3, and MW4 have been sampled since January 1994, well MW5 has been sampled since ' March 1996, well MW6 has been sampled since April 1997, and well MW7 has been sampled since April 1998 Groundwater analytical data is included in Table 2 Historically, petroleum hydrocarbons have been consistently detected"Wells MW1, MW3, MW4, MW5, VE1, VE3, and ' VE6 Petroleum hydrocarbons have only been detected sporadically at very low concentrations in wells MW2, MW6, MW7, and VW7 Detectable concentrations of TPHg and BTEX ' compounds were detected in wells MW1, MW3, MW4 and MW5 until November 2003 However, concentrations of petroleum hydrocarbons in all of these wells have generally decreased since monitoring was initiated at the site ' The following is a summary of groundwater impact based on laboratory analytical data from previous subsurface reports and quarterly groundwater monitoring reports ' • Groundwater samples have been collected from well MW 1 and analyzed since December 1990 Well MW 1 was the first groundwater monitoring well installed at the site and is located directly adjacent to the former UST locations and is therefore, the closest well to w 1271421repoM\closure doc 13 1 �