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FE C'EE� W E 0 <br /> JAN 14 2008 <br /> ENVIRONMENT HEALTH <br /> January 11, 2008 PERMIT/SERVICES <br /> San Joaquin County Environmental Health Department <br /> LOP/Site Mitigation Unit IV <br /> 600 East Main Street <br /> Stockton, California 95202 <br /> Attention: Mr. Frank Girardi <br /> Re: Addendum to <br /> Revised Draft Work Plan and <br /> Preliminary Site Hydrogeologic Conceptual Model <br /> Additional 1,2-DCA Investigation <br /> RWQCB Case No. SLT5S033 <br /> Local Agency Case No. 1882 t <br /> Former American Forest Products Facility <br /> 2801 West Lane <br /> Stockton, California <br /> URS Project No. 17322736 <br /> i <br /> Dear Mr. Girardi: <br /> i <br /> Introduction <br /> On behalf of Mr. William Bergvall, consultant for erican Forest Products Company LP, URS <br /> Corporation Americas (URS) is submitting this work plan addendum to the above-referenced work plan <br /> previously submitted October 22, 2007. This addendum has been prepared in response to comments on <br /> the work plan received from the San Joaquin County Environmental Health Department (SJCEHD) in <br /> your letter dated December 3, 2007. <br /> i <br /> Summary of Octoher 2007 Work Plan <br /> This work plan summarized data gaps in the definition of a plume of 1,2-DCA emanating from a former <br /> waste oil underground storage tank (UST) at the east end of a former maintenance shop. Data gaps in the <br /> lateral definition of the plume were found to exist downgradient to the north,land laterally to the east and <br /> southwest. This plume was identified by groundwater sa Itriple data from wells screened generally in the <br /> range of 60 to 70 feet below ground surface (bgs). The wrk plan asserted that data from monitoring well <br /> DMW-8, with a screen interval of 80 to 90 feet bgs, idicated that the distribution of 1,2-DCA was <br /> limited to the shallower groundwater at the site. This was based on the fact that this well is located in the <br /> area of the highest shallow concentrations of 1,2-DCA(see Figure 1). <br /> To address the data gaps in lateral distribution of 1,2-DC A, the work plan proposed installation of four <br /> groundwater monitoring wells to be completed with 10-foot screens within the 45 to 70 foot bgs interval, <br /> URS Corporation <br /> 2870 Gateway Oaks Drive,Suite 300 <br /> Sacramento,CA 95833 <br /> Tel:996.679.2200 <br /> Fax:916.679.2900 <br />