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t ' <br /> 28 November 2005 <br /> AGE-NC Project No 96-0232 <br /> Page 7 of 8 <br /> evident between March and June 2004 from wells EW-5,EW-7, EW-8 and EW-10(northerntrench <br /> line) and from well EW-9 (fuel dispenser island area) The March-June 2004 `spikes' may be <br /> attributed to the above referenced third MTBE-impacted ground water plume being drawn towards <br /> `� <br /> the Flag City Chevron extraction wells ` - _ - _ - _ - I---- <br /> Based <br /> --ryBased on generally low MTBE detections (below 20 µg/l) in influent samples since March 2004, <br /> ground water pump-anal-treat operations were fully suspended at the site on 17 August 2004 <br /> Between November 2000 and August 2004, a total volume of approximately 27,086,201 gallons of <br /> MTBE-impacted water was treated at the site <br /> A significant detection of MTBE was observed from Flag City Chevron well MW-2 during <br /> December 2004, March 2005 and Jude 2005, AGE has modeled the increase as related to the - <br /> suspension of the ground water pump-and-treat activities(17 August 2004),in effect causing MTBE- <br /> impacted ground water located near the Flag City Chevron UST/fuel dispenser area to migrate east- <br /> southeast relative to the natural ground water flow direction <br /> 5.0 RECOMMENDATIONS <br /> (� Based on the findings and conclusions of this investigation, AGE recommends <br /> C No further subsurface investigation at this time Flag City Chevron has adequately assessed <br /> MTBE-impacted soil and ground water associated with the Flag City Chevron UAR <br /> Y Recision of Cleanup and Abatement Order (C&A) 5-00-700 <br /> 0 Consideration of the facility for closure as a low risk ground water site <br /> o In accordance with applicable regulations and as part of the site closure preparations,all Flag <br /> City Chevron ground water monitoring wells and/or ground water extraction wells that <br /> cannot be utilized by the adjoining Three B's Truck Plaza-New West Petroleum <br /> investigations should be properly abandoned, AGE has contacted the consultants for New <br /> West Petroleum and the San Joaquin County Environmental Health Department to discuss <br /> the possibility of transferring responsibility of certain monitoring that could still be utilized <br /> for their investigation <br /> 6.0. 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 hydrogeologic <br /> Advanced GeoEnvironmental,Inc <br />