SITE INFORMATION AND CORRESPONDENCE

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City of Tracy - PW • 209-eai-4472 10/12/01.47P P.002 City of Tracy and Georgia Pacific Corporation Indemnity Agreement Page 2 be S micrograms per liter(µg/,)chloroform. Groundwater will be extracted from existing wells RW-1 and RW-2,located immediately north of the Basin,and pumped through an aeration system consisting of a series of manifolds and spray heads. Treatment of the extracted groundwater will occur through volatilization of chloroform as the water droplets fall into the Basin. Effluent will be returned to the Basin for infiltration to the shallow water-bearing unit. Pilot test results obtained in July 1998 (Groundwater Extraction/Aeration Pilot Test and Semi-Annual Monitoring Report, Former Georgic-Pacific Corporation Chemical Packaging Plant, 75 W Valpico Road, Tracy, California, September 11, 1998) indicated that the percolation tate of the Basin is less than the projected flow rate of the remediation system. Therefore, a portion of the treated effluent will be pumped to the irrigation canal, a facility owned by the West Side Irrigation District(WS1D)to maintain a static water level within the Basin. Recirculation of treated water via percolation is expected to enhance remediation of subsurface materials by washing chloroform from the unsaturated zone into shallow groundwater, where it will be transported to the extraction wells and removed. The groundwater mounding expected to occur immediately beneath the Basin will be hydraulically controlled by the two extraction wells G-P shall ensure that the groundwater remediation facilities aro operated in a manner that does not interfere with City facilities or City use of the Basin. Use of the Basin by G-P shall be monitored by the Public Works Director or his designee. G-P shall ensure that the groundwater remediation facilities are operated to meet all RWQCB discharge requirements in compliance with the NPDES and the WDR. G-P shall be responsible for all of the operations and maintenance of the groundwater remediation system. GP shall be responsible for the maintenance of the Basin, including weed control. G-P shall be responsible for controlling the discharge from the groundwater remediation facilities and the Basin to meet the operating requirements of WSID and the G-P NPDES permit. G-P shall be responsible for any damages to the City Basin or City facilities, such as the basin fencing,and well-site property arising from G-P's use of the City Basin. - c.Tim in¢ The estimated time for the completion of this remediation project is December 31, 2005 and the timing shall be strictly adhered to unless otherwise modified in writing.