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t <br /> California Regi,)nal Water Quality C trol Board <br /> Central Valley Region <br /> Robert Schneider,Chair <br /> Terry Tamminen Arnold Schwarzenegger <br /> Secretary for Sacramento Main Office Governor <br /> Environmental Internet Address: http://www.swrcb.ca.gov/rwgcb5 i <br /> Protection 11020 Sun Center Drive#f200 Rancho Cordova,CA 95670-6114 pcv C[�M �UPhone(916)464-3291 <br /> pUG p 3 2004 <br /> 30 July 2004 <br /> kNV�R MITISER�CES <br /> Mr. Ken Price pER <br /> Miller Springs Remediation Management, Inc. <br /> 2480 Fortune Drive, Suite 300 <br /> Lexington, KY 40509 <br /> REMEDIAL PUMPING OPTIMIZATION WORKPLAN, FORMER OCCIDENTAL CHEMICAL <br /> CORPORATION FACILITY, 16777 SOUTH HOWLAND ROAD, LATHROP, SAN JOAQUIN <br /> COUNTY <br /> The Regional Water Quality Control Board(Regional Board) staff has reviewed the <br /> Remedial Pumping Optimization Workplan (Workplan) dated 30 July 2003 prepared and submitted by <br /> The Source Group on behalf Miller Springs Remediation Management, Inc. The purpose of the <br /> Remedial Pumping Optimization Program is to provide a more cost effective remedial solution while <br /> continuing to maintain hydraulic control of groundwater impacted by pesticides and fumigants, mainly <br /> dibromochloropropane (DBCP), ethylene dibromide (EDB), and sulfolane. The remedial system <br /> operation started in 1992 and consists of an extraction well network, a 500 gallons per minute (gpm) <br /> capacity treatment consisting of granular activated carbon (GAC), and an injection well network for <br /> disposal of treated water. <br /> The proposed Workplan includes: <br /> • Operation of the groundwater remedial system on a six-month cycled pumping schedule (i.e. six <br /> months on and six months off) for a two-year period following one year of suspension of active <br /> pumping for collection of additional hydrogeologic and water quality data to quantify regional <br /> groundwater gradients especially as related to the increased pumping associated with the City of <br /> Lathrop supply wells (LDW-22 and LDW-21) to the southwest of the Site; <br /> • Installation of three additional groundwater monitoring wells as part of the contingency monitoring <br /> well network; <br /> • Continuation of groundwater and remedial system monitoring and reporting in accordance with the <br /> Monitoring and Reporting Program (MRP) and Waste Discharge Requirements (ADRs) established <br /> for the Site. Additionally, semi-annual sampling of 31 wells as part of the contingency monitoring <br /> well network will be conducted; <br /> • Maintenance of the remedial system to ensure the system is in operational condition for contingency <br /> purposes; <br /> California Environmental Protection Agency <br /> �a Recycled Paper <br />