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Mr. William Aravanis • - 2 - . January 12, 2007 <br /> Vertical evaluation of soil vapor to groundwater was not completed, as refusal was <br /> encountered in the four deep borings between 26 and 29 feet bgs. Therefore, a sample was <br /> collected at the deepest depth reached in each deeper boring. The highest concentrations of <br /> several different chlorinated VOCs were detected at 29 feet in SV-7 located in Area B, and the <br /> detected constituents in this boring showed a clear increasing trend with depth. However, <br /> VOC concentration trends with depth were not consistent site-wide. <br /> Geomatrix has proposed that additional soil vapor investigation be conducted. The work will <br /> include (1) completion of the vertical evaluation of soil vapor to groundwater; and (2) collection <br /> of additional shallow soil vapor samples (while drilling deeper borings). The shallow data will <br /> be used to develop site-specific human health risk data, and to evaluate the potential for vapor <br /> intrusion. All new soil vapor data will be used to further evaluate the need for the installation <br /> of an SVE system to remediate VOC impacted soils. <br /> Staff concurs with the recommendations presented, as additional investigation needs to be <br /> conducted. We recommend a detailed work plan be prepared and submitted for our review, <br /> comment, and concurrence. Within 30 days of receipt of this letter, please provide an update <br /> on your progress in developing the additional investigation work plan, and your tentative <br /> schedule for implementation. <br /> If you have any questions or comments, please contact Marie McCrink at 916-464-4816, or by <br /> email at mtmccrink(a)waterboards.ca.gov. <br /> J <br /> �. /6, � <br /> Marie McCrink, P.G., C.H. <br /> Associate Engineering Geologist <br /> Private Sites Cleanup Unit <br /> cc: Mr. R Morgan Gilhuly, Esq., Barg Coffin Lewis & Trapp, LLP, San Francisco <br /> Mr. Joe Hohenrieder, Lustre-Cal Nameplate Corp, Lodi <br /> Mr. Stephen Schwabauer, Esq., Attorney, City of Lodi <br /> Mr. Richard C. Prima, Jr., Public Works Director, City of Lodi <br /> Mr. Harlan Knoll, San Joaquin County Environmental Health Department, Stockt <br />