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Page 2,4075 Main Street 0 <br /> SJC/EHD approves the installation of two shallow ozone infusion points, one near MW-2 <br /> and one near MW-3. Sufficient justification has not been provided for injecting into the <br /> predominately fine-grained interval at 85-92.5 feet below surface grade (bsg), or at the <br /> 111.5 feet bsg depth. Onsite monitoring well MW-8, which is built to 105 feet bsg, is not <br /> impacted. The existing ozone infusion points were proposed with targeted depths of 72 <br /> and 110 feet bsg, based on apparent water bearing units logged in soil borings CPT-1 and <br /> SB-1. In correspondence dated November 7, 2003, SJC/EHD recommended that before <br /> ozone infusion points were installed to 110 feet bsg the proposed deep groundwater <br /> monitoring well, MW-8, be installed and sampled to determine if contamination existed at <br /> this depth. This recommendation was not heeded; the infusion points were installed a <br /> month before MW-8 was installed. <br /> Ozone infusion was approved for use at this site as an interim remediation of the onsite <br /> groundwater contamination. It was also noted in the November 7, 2003 SJC/EHD <br /> correspondence that remediation of the onsite soil contamination is of concern. Please <br /> submit a feasibility study for addressing the onsite vadose zone contamination. The <br /> feasibility study is due no later than November 30, 2007. <br /> The submitted Work Plan does not address investigation of the offsite contamination. <br /> Please proceed with submittal of an addendum to investigate the lateral and vertical <br /> extent of the offsite contamination in the down-gradient direction. The addendum is due <br /> for submittal no later than November 16, 2007. <br /> To summarize; SJC/EHD approves the installation of two shallow ozone infusion points, <br /> one near MW-2 and one near MW-3, and one shallow groundwater monitoring well near <br /> MW-2. Please proceed with submittal of a San Joaquin County Well Permit Application, <br /> required $89.00 permit fee and $294.00 permit inspection fee and with scheduling the <br /> approved work. The onsite ozone infusion system has been non-operational since <br /> December 2006. You were directed in the July 23, 2007 letter to resume the onsite <br /> groundwater remediation no later than October 26, 2007; the new wells need to be <br /> installed, and remediation of the groundwater needs to resume, as soon as possible. <br /> If you have any questions please call Lori Duncan at (209) 468-0337 or Nuel Henderson <br /> at (209)468-3436. <br /> Donna Heran, REHS, Director <br /> Environmental Health Department <br /> coirLori Duncan,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 /> Lorraine Sawyer, PG, ATC <br />