SITE INFORMATION AND CORRESPONDENCE

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Messrs Trommer and L.4 _ Preliminary Five-Year Review Letters Various Sites 21 July 2008 Page 3 of 3 issued a directive to prepare a feasibility study over a year ago; the EHD believes the site would be amenable to excavation with removal of impacted groundwater seeping into the excavation. 2420 Turner Road The CUF agreed with the EHD that active remediation should begin as soon as feasible to achieve WQ0s in a timely manner. The EHD agrees with this recommendation. Eleven monitoring wells (two deep, nine shallow) have been installed on the site; recently five vapor extraction wells and seven IAS wells have been installed and plumbed to an enclosure; a permit has been issued by the air board; at this point a remediation unit must be installed and a power connection established to initiate remediation. 466 Moffat Boulevard The CUF has recommended that the site be considered for closure. The EHD believes the plume is delineated vertically and laterally, but covers an area approximately 100 feet by 100 feet and the plume has total petroleum hydrocarbons quantified as gasoline (TPHg) at concentrations that varies into the low tens of thousands of parts per billion. The EHD believes the TPHg concentrations are too high to obtain a concurrence on a site closure recommendation; therefore the EHD believes some remediation of impacted groundwater is required. To that end, the EHD has directed preparation of a remedial action plan; the RP has proposed dual-phase extraction, which the EHD is evaluating. Questions or comments should be directed to the appropriate caseworker. Sincerely, JJ 1<bAc-c( Harlin Knoll, REHS Senior Registered Environmental Health Specialist Nuel Henderson, PG Engineering Geologist 5-Year Review Comment Letter 072108.doc 6r14 Lori Duncan, REHS Senior Registered Environmental Health Specialist Margaret tgorio, REH Program Coordinator AL:se