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15 March 2002 <br /> AGE-NC Project No 97-0249 <br /> Page 9 of 10 <br /> • 1,2-DCA was detected in 3 of 8 water samples from HU-5, in one water sample from HU-1 <br /> and in one water sample from HU-4, the 1,2-DCA occurrences may be related <br /> • Based on grab ground water samples collected at borings P-15 and P-17, fuel-impact at the <br /> site appears to extend to more than 120 feet bsg, variable concentrations were observed with <br /> depth <br /> • The vertical extent of petroleum-impacted ground water has not been fully delineated on- or <br /> off-site <br /> 4.0. RECOMMENDATIONS <br /> Based upon the CPT investigation results during the fourth quarter 2001, AGE recommends <br /> 1 Continued quarterly ground water monitoring, the next quarterly ground water monitoring <br /> event is tentatively scheduled for March 2002 <br /> 2 Installation of multi-level deep screened ground water monitoring wells at the site, the screen <br /> intervals for the deep-screened monitoring wells should be placed to define and monitor the <br /> lateral extent of the ground water plume in selected informal hydrologic units <br /> 3 Conduct ground water remediation feasibility studies at the site in shallow and deeper <br /> hydrologic zones Ground water pump testing should be performed at the site to evaluate a <br /> general radius of influence and capture zone during ground water extraction The proposed <br /> aquifer pump tests will be designed to obtain general aquifer characteristics such as hydraulic <br /> conductivity, storativity, transmissivity and draw-down at a constant pumping rate <br /> 4 Preparation of a feasibility study work plan for an in-situ air sparge pilot test <br /> 5 Install and continuously operate a ground water extraction system (interim remediation) in <br /> the area of MW-3, P-1, P-2, P-3, P-15 and P-17 to inhibit further off-site migration of the <br /> fuel-impacted ground water plume and to protect beneficial water usages of the on-site <br /> domestic water well and the municipal water well (CSA-2) located approximately 1,000 feet <br /> southeast of the site <br /> 5 0. LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily exercised by <br /> environmental consultants practicing in this or similar localities The findings were based mainly <br /> upon analytical results provided by an independent laboratory Evaluations of the geologic/hydro- <br /> Advanced GeoEnvi ron mental,Inc <br />