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Messrs Trommer and L, eon 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 EI 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 /> 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 /> l <br /> 5-Year Review Comment Letter 061608.doc <br />