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h <br /> ' Page 2,8200 N. Hwy. 99 <br /> 3 M <br /> evaluation of the analytical results from groundwater samples collected since GWE <br /> began indicate the treatment has been effective in reducing contaminant concentrations <br /> by one to two orders of magnitude in all shallow wells except in MW-12. GZA states in <br /> the work plan that the current mass of dissolved methyl tertiary butyl ether in the shallow <br /> groundwater is only 15-20 pounds, though they did not provide the calculation or data <br /> that they used to make that determination. Please submit the calculation and data to <br /> SJCIEHD no later than August 10, 2007. <br /> A feasibility study of remediation methods to enhance the cleanup of the groundwater- <br /> contamination was due with this work plan, but was not provided. Instead, GZA <br /> proposes to prepare an ozone injection pilot study work plan if the results-of the <br /> confirmation soil boring indicate residual saturated soil contamination, which could be a <br /> continuing source of contamination to the groundwater, is still present in the former UST <br /> area. While source area removal does need to be addressed, it does not seem likely it <br /> will enhance the remediation of the groundwater contamination remaining in and near <br /> MW-12, which is some distance removed from the onsite source area. <br /> Please proceed with.submittal of the now overdue feasibility study for enhancement of <br /> the remediation of the remaining groundwater contamination. The study should <br /> compare at least two cleanup alternatives for both cost and potential remedial <br /> effectiveness. SJCIEHD cannot approve the installation of additional remediation wells <br /> without the study.. The.feasibility study is due no later than August 10, 2007. <br /> Please proceed.with submittal of a San Joaquin County well permit application, required. <br /> $89.00 permit fee.and $285.00 permit inspection fee for installation of the approved soil ; <br /> boring.and groundwater monitoring wells. The approved work must be completed.no <br /> later than September 28, 2007; a report of findings must be submitted within 60 days <br /> following completion of the fieldwork. <br /> If you have any questions please call. Lori.Duncan at (209) 468-0337. <br /> Donna Heran, REHS, Director <br /> Environmental Health Department <br /> Lori Duncan,.Senior REHS Nuel C. Henderson, Jr., PG <br /> LOP/Site Mitigation Unit IV LOP/Site Mitigation, Unit IV. <br /> cc: James Barton, PG, CVRWQCB <br /> Greg Stahl, PG, Ground Zero Analysis <br />