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07 February 2001 <br /> AGE-NC Project No 95-0130 <br /> ' Page 7 of 8 <br /> ' MW-2, BTEX compounds were only detected in P-8 and decreased with depth to 137 feet <br /> bsg All four BTEX compounds were detected in First Water Zone, Second Water Zone and <br /> Third Water Zone, only benzene and toluene were detected in Primary Aquifer Zone <br /> • The greatest PCE-impact was reported from the Third Water Zone sample collected from P-7 <br /> at a depth of 101 to 104 feet bsg,First Water Zone, Second Water Zone and Primary Aquifer <br /> ' Zone PCE-impacts were reported from from P-8 at depths of 112 to 115 feet bsg and 134 to <br /> 137 feet bsg, from P-9 at a depth of 83 to 86 feet bsg and from P-10 at a depth of 82 to 85 <br /> feet bsg, the PCE-impact appears to extend to depths greater than 137 feet bsg <br /> • Low concentrations of TCE and 1,2-DCE were encountered at depths between 43 and 76 feet <br /> bsg, within the First Water Zone and Second Water Zone (Figures 5 and 6) Shallow ground <br /> water samples from wells MW-1 through MW-5 have not been analyzed for TCE or PCE <br /> ' 40. RECOMMENDATIONS <br /> . Based upon the CPT investigation results during the fourth quarter 2000, AGE recommends <br /> • C'onl,niied quarterly ground NNatcr monito,itis, Lite next quarterly ground water monitoring <br /> event is tentatively scheduled for March 2001 <br /> Quarterly ground water monitoring well samples should include a full analysis by LPA � <br /> Method 8260 for constituents of concern <br /> • Conduct a ground water pump testing to obtain general aquifer characteristics such as <br /> hydraulic conductivity, transmissivity, storativity and drawdown at various pumping rates <br /> ' Results of the pump test would be utilized to estimate a radius of influence for the zone of <br /> capture of dissolved petroleum hydrocarbons <br /> • Install and continuously operate a ground water extraction system (interim remediation) in ! <br /> the area of MW-1 and MW-2 to inhibit further off-site migration of the fuel-impacted ground <br /> water plume <br /> ' • Additional vertical ground water assessment is warranted to characterize the vertical extent <br /> of hydrocarbon and solvent-impacted ground water at the site <br /> • Installation of additional shallow and deep-screened ground water monitoring wells based <br /> ' on the findings of the existing shallow ground water monitoring wells and CPT soil borings, <br /> the screen intervals for the deep-screened monitonng wells will be placed to define and <br /> ' monitor the vertical extent of the ground water plume in each informal hydrologic unit <br /> • Review of historic records which should include records on file with the local fire <br /> department building department or planning division and cross-referenced telehone <br /> t� p <br /> 4dvanced(,eoEnvironmcntal JUL <br />; � 111 <br />