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y <br /> Raymond Investment Corporation Page 2 <br /> 730 Channel Street <br /> July 25s 2008 <br /> Stockton, California 95202 <br /> • Cross sections showing subsurface geological.features, depth to groundwater, man-made i <br /> conduits, monitoring well construction and the interpreted vertical extent of soil and <br /> groundwater contamination; <br /> • Cross-plots of key chemical concentrations verses time for representative wells that <br /> demonstrate significant contaminant concentration trends; <br /> • Summary tables of contaminant concentrations in the different media; <br /> • Rose diagram showing directions of dominant groundwater flow; <br /> • Well and boring logs (including con struction/screening); and <br /> • Narrative description of the SCM that describes controls on contaminant distribution; <br /> contaminant migration mechanisms, pathways and rates; plume disposition over time; and <br /> sorbed and dissolved contaminant masses. <br /> While not necessarily showing all data in diagrams and drawings, an adequate SCM can be utilized to <br /> account for most of the known data, and as previously noted, to evaluate whether additional investigation i <br /> is needed; and to. evaluate the fate of impacted groundwater with an estimate of when background <br /> conditions will be restored. All analytical data should be included in tables. Methods and calculations of <br /> contaminant masses should be included in the SCM, and may be submitted as an appendix. <br /> The SCM should be updated as new data are acquired that cause a change of interpretation or expands the <br /> model until model modifications are not needed to explain subsequently acquired data. As the SCM <br /> becomes complete, it can be utilized to reasonably predict additional investigation results and plume <br /> response to various remedial technologies or to changes in groundwater flow regime. The model should <br /> be submitted to the EHD by September 25, 2008, and adequately demonstrate all interpretations and I <br /> opinions. <br /> The EHD is not being informed of scheduled quarterly groundwater monitoring events. Notify the EHD <br /> of the time and date at least forty-eight hours prior to the sampling event so an inspector can be present. <br /> i <br /> If you have any questions regarding this letter please contact Vicki McCartney, Senior Registered <br /> Environmental Health Specialist, at(209)468-9852,or by email at vmccartney@sjcehd.com. <br /> i <br /> Sincerely, <br /> Victoria L. McCartney, REHS Nuel C. enderson,Jr., PG <br /> Senior Registered Environmental Health Specialist Engineering Geologist <br /> c: Mr. Bill A. Cook III, PG, Condor Earth Technologies, Incorporated, 188 Frank West Circle, Suite 1, <br /> Stockton, California 95206 <br /> Mr. James L.L. Barton, PG, California Regional Water Quality Control Board Central Valley Region, <br /> 11020 Sun Center Drive, Suite 200, Rancho Cordova,California 95670 <br />