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0 <br /> [�D <br /> 5 2008 <br /> shaW' Shaw Environmental, Inc. E PEq, ,.T POFSERVICES HEALTH <br /> January 18, 2008 A World of Solutions" <br /> Mr. James L.L. Barton, P.G. <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> 11020 Sun Center Drive, #200 <br /> Rancho Cordova, CA 95670-6114 <br /> Subject: Response to Comments dated December 27,2007 Concerning the November 2007 Work <br /> Plan and Feasibility Study for the Transmission Shop Site at 515 W. Charter Way, <br /> Stockton,California <br /> Dear Mr. Barton: <br /> This letter addresses two main comments presented in your letter to Mr. Don Rodgers dated December 27, 2007. <br /> In response to Comment#1, estimated rough-order-of magnitude(ROM)costs for the four remedial alternatives, <br /> discussed in the November 2007 Feasibility Study for Onsite Petroleum Hydrocarbon Remediation,are provided <br /> in the updated Table 5-1 (see attached). The estimated ROM costs are provided solely for alternative comparison <br /> purposes and shall not be interpreted as the actual costs for the alternatives. <br /> With regards to Comment#2, after further research and review of existing well data from the site as well as <br /> adjacent facilities, Shaw concurs with the Regional Board's recommendation for installing an additional deep well <br /> for the purpose of determining the deep zone hydraulic gradient and direction. Additional lithologic research <br /> from adjacent properties,440,441,and 508 West Charter Way, illustrates a potential zone of reduced <br /> permeability from approximately 95 to 105 feet below ground surface(bgs). The screen interval for the currently <br /> proposed deep well(MW-I 1D) is 80 to 90 feet bgs, whereas the screen intervals for deep wells at adjacent sites <br /> 440 and 441 West Charter Way range from 105 to 122 feet bgs. h is therefore unlikely that hydrogeologic <br /> communication exists between(1)MW4RD and MW-I ID at 515 West Charter Way and(2)deep wells MW-8C <br /> and MW-1C at 441 West Charter Way and MW-3C, MW-IOC, MW-I IC, MW-18C, and MW-19C at 440 West <br /> Charter Way. As such, an additional deep well will be installed and screened from 80 to 90 feet bgs to <br /> supplement the hydrogeologic information required. The location of this new well,MW-12D, is shown in the <br /> attached Figure 9a. This figure shall replace Figure 9 of the November 2007 Work Plan for Further Delineation <br /> of Groundwater Petroleum Hydrocarbon Plume(Work Plan). This additional well will be installed in two steps <br /> as described in the Work Plan. <br /> As for the 3`d quarter groundwater monitoring report referenced in the Work Plan, Shaw issued a hard copy of the <br /> report to Regional Board on January 7, 2008. The electronic versions of the report, the Work Plan,and the <br /> Feasibility Study were also uploaded onto GeoTracker on January 9, 2008. Shaw believes the Geotracker record <br /> for this site should be up-to-date. <br /> 1326 NORTH MARKET BLVD., SACRAMENTO, CA 95834 • 916.565.4358 • FAX 916.565.4356 <br />