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I 30 December 1999 AGE-NC Project No 95-0104 Page 6 of 7 • Groundwater flow direction in the area of MW-1 through MW-6 was generally toward the northeast at a gradient of 0 002 ft/ft, or approximately 11 feet per mile (Figure 3) • Dissolved TPH-g and BTEX compounds do not appear to be significant in the area bound by wells MW-1, MW-5, MW-6 and VW-1 • Prior to initiation of the SVE pilot test, dissolved petroleum hydrocarbons detected in water samples collected from VW-1 indicated this well was within the dissolved petroleum hydrocarbon "core area"of the plume However, it appears that operation of the SVE pilot test has reduced dissolved petroleum hydrocarbons in the area of VW-1 to nearly non- detectable concentrations Based on data collected between 27 August 1999 and 14 December 1999 SVE pilot test, AGE concludes • A general trend of declining PID field measurements between the August-December PID field measurements �. • A general trend of declining TPH-g and BTEX compound vapor concentrations between the August-December SVE pilot test • The volume of hydrocarbons extracted from VW-1 between 27 August 1999 and 14 ' December 1999 was calculated to be approximately 59 15 gallons of petroleum hydrocarbons (Appendix E) • Based on mass/volume calculations of total impacted petroleum hydrocarbon soil to place at the site (Revised Corr ective Action Plan -January 1997, dated 18 February 1997), it was estimated that a hydrocarbon mass equivalent to approximately 300 gallons of gasoline was I present in the soil at the site AGE estimated that operation of the SVE system had previously removed 99 36 gallons of petroleum hydrocarbons (Quay terly Repos t-July 1999, dated 07 September 1999), The additional removal of 59 56 gallons of petroleum h drocarbons totals Iremoval of approximately 158 92 gallons to date, or approximate 53 percent f petroleum hydrocarbons formerly impacting sol at t e site • As noted in the Revised Corrective Action Plan -January 1997, dated 18 February 1997, the theoretical SVE radius of influence of VW-1 is approximately 20 feet, and all the known impacted soil hes within 15 feet of VW-1, VW-1 is adequately screened and placed to address all known impacted soil • PID field measurements, TPH-g concentrations and BTEX concentrations were plotted vs Itime for the March 1999 through December 1999 SVE pilot test (Appendix F) Generally, • the plots depict a steep curve during the March-Apnl 1999 portion of the SVE pilot test, the steep curve demonstrates that the majority of petroleum hydrocarbon vapor extraction ' occurred during this time The plots depicts a shallow curve with some rebound peaks during Advanced GeoEmironmenlal, Inc