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Messrs Trommer and Lon 16 June 2008 <br /> Preliminary Five-Year Review Letters Page 3 of 7 <br /> Various Sites <br /> UST #1 area has not been delineated; nor has the cross-gradient extent of the <br /> impacted groundwater centered on the former UST#2 area. <br /> 2132 Mariposa Road, E <br /> • CUF recommended evaluation of remedial technologies and potential for vapor <br /> intrusion; the EHD agrees with this recommendation and has directed.evaluation <br /> of remedial technologies. The consultant has requested delay in the evaluation <br /> pending the results?of additional site investigation, a work plan for which is in <br /> preparation. <br /> 3430 El Dorado Street, S. <br /> • The CUF has recommended•continued operation of the SVE/IAS systems with <br /> periodic reevaluation; the EHD agrees with this recommendation. <br /> 1301 Kettleman Road, W. <br /> • The CUF has recommended evaluation of air or ozone sparging to achieve water <br /> quality objectives. more. quickly; the EHD,agrees that remediation is appropriate <br /> for this site and has approved a pump and treat system. The consultant has <br /> installed two extraction wells and recently.obtained the discharge permit; the <br /> system is expected to be.in operation in August of this year. <br /> 4444 Pershing Avenue,. N. <br /> • The CUF has recommended assessment of the current remediation. technology <br /> effectiveness and amending as necessary; however there has been no recent <br /> active remediation on this site. Contaminants on the site have been difficult to <br /> address as the bulk of the sorbed mass`is in fine-grained soil in the saturated. <br /> zone. A work plan has been.approved to install a deep monitoring well, screened. <br /> between 50 and 55 feet bsg, and additional soil borings. The site has been <br /> i evaluated for vapor,intrusion potential and has been reported as having a low <br /> potential. <br /> 4004 EI Dorado Street, S. <br /> • The CUF has recommended reevaluation of the treatment system and evaluation <br /> of the potential for. IAS near MW-1 to accelerate the remediation process. The. <br /> EHD agrees and will issue a directive letter to address the MW-1 area as <br /> recommended. <br /> 1766 Monte-Diablo Avenue. <br /> • The CUF has recommended reassessment of the efficacy of the current <br /> groundwater remediation system and implementation of additional technologies <br /> as appropriate- The EHD agrees with the recommendation and has recently <br /> approved a proposal'to evaluate DPE.and has directed submittal of a work plan <br /> to conduct the pilot test. <br /> i <br /> 5-Year Review Comment Letter 061608.doc <br />