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' 15 October 2002 <br /> • AGE-NC Project No 96-0232 <br />' Page 2 of 19 <br />' 2.0 GROUND WATER PUMP AND TREAT REMEDIATION SYSTEM <br /> Between 13 June through 25 September 2002(third quarter),a ground water pump-and-treat system <br />' was in continuous operation at the site, however, the pump-and-treat system was suspended at the <br /> site on 25 September 2002 due to a detection of hexavalent chromium in the effluent grab water <br /> sample at a concentration of 0 30 gg/l The pump-and-treat system effluent was resampled on 25 <br /> t September 2002, and the laboratory reported non-detectable levels of hexavalent chromium (less <br /> than 0 5 gg/1) Ground water pump-and-treat operation and maintenance procedures for the site were <br /> outlined in AGE's Final Remediation Plan <br /> 1 <br /> 2 1 GROUND WATER PUMP AND TREAT OPERATION <br />' The Flag City Chevron ground water um -and-treats stem was designed tooperate at a maximum <br />' flow rate of 25 gallons per minute(GPM) On-site extraction wells EW-4,EW-5,EW-9 and EW-10 <br /> were adjusted at each well-head to continuously extract ground water during the third quarter at a <br /> flow rate of approximately 5 to 6 GPM, extraction well EW-8 was substituted for well EW-9 on 08 <br /> August 2002 due to a pump malfunction <br /> During the third quarter, all extracted ground water was routed through a ground water treatment <br /> system consisting of granular activated carbon(GAC) and Sunsolve® Following treatment, water <br /> was discharged to the Coldam ditch(located approximately 450 feet south of the site) at a flow rate <br /> of approximately 24 GPM Field notes of ground water pump and treat operation and maintenance <br />' activities are in Appendix A <br /> Based on effluent flow meter readings (Appendix A, Table 8), approximately 1,485,238 gallons of <br /> treated water were extracted and discharged to the Coldam ditch during the third quarter under <br /> RWQCB General Order 5-00-119 for discharge to surface waters of ground water from cleanup of <br /> petroleum fuel pollution Since initiation of the ground water pump and treat remediation system on <br />' 20 November 2000, a total volume of approximately 15,45 8,051 gallons of MTBE-impacted water <br /> has been treated and discharged to the Coldani ditch under RWQCB waste water discharge permit <br /> no CAG915001 [National Pollutant Discharge Elimination System (NPDES)] <br /> 1 <br />' 2 2 GROUND WATER PUMP AND TREAT SAMPLING PROCEDURES <br /> Samples of ground water pump-and-treat influent and effluent water were collected from valved <br />' sampling ports located upstream (influent) and downstream (effluent) of the treatment unit In <br /> addition,water samples were collected from receiving water sampling stations located in the Coldam <br /> ditch approximately 50 feet upstream(R-1)and 80 feet downstream(R-2)of the point of discharge, <br /> I <br /> Advanced GeoEnviranmental,lnc <br />