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18 January 2004 AGE-NC Project No 95-0141 ' Page 4 of 5 likely did not yield samples fully representative of ground water conditions near the top of the saturated zone,where fuel hydrocarbons would be expected to have the greatest impact • During the third quarter 2003, TPH-g was detected In ground water samples collected from ' five of the fifteen wells at the site at concentrations as high as 130,000 ug/l TPH-g-impacted shallow ground water has been defined(Figure 5),however,the TPH-g-impact to the deeper ground water zone has not been defined toward the south, east and north (Figure 6) ' 0 During the third quarter 2003, BTEX constituent was detected In four of the fifteen wells ground water wells The benzene concentrations In all four wells exceeds the DHS's Maximum Contaminant Level(MCL) for benzene in drinking water The concentrations of ' toluene, ethylbenzene and total xylenes in well EX-1 were significantly above their respective MCLS ' During the third quarter 2003, 1,2-DCA was detected in ground water samples collected from ten of the fifteen wells at the site at concentrations as high as 190 µg/1 (EX-1) The detected concentrations of 1,2-DCA were above the MCL 1,2-DCA-impacted shallow ground water ' has not been defined toward the east, and 1,2-DCA-impacted deeper ground water zone has not been defined toward the south,east and north A map illustrating the approximate extent of 1,2-DCA In shallow and deep ground water Is presented in Figures 7 and 8 ' 5.0. RECOMMENDATIONS Based on the results of this and previous investigations, AGE recommends tContinued quarterly monitoring of the ground water monitoring network, • 0 Completion of the ground water extraction feasibility pilot test proposed in the AGE- prepared Work Plan Addendum, dated 09 April 2002, • Preparation of a work plan for vertical assessment and monitoring ofthe dissolved petroleum hydrocarbon-impacted and additive-impacted ground water at the site and ' a Preparation of a work plan for remediation ofpetroleum hydrocarbon-impacted ground water at the site ' 6.0. LIMITATIONS Our professional services were performed using that degree of care and skill ordinarily exercised by ' environmental consultants practicing in this or similar localities The findings were based mainly upon analytical results provided by an independent laboratory Evaluations of the hydrogeologic conditions at the site have been made from a limited number of available data points(i a monitoring Advanced CeoEnvironmental,Inc