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• l Messrs Trommer and Larsoi4April 29 2009 7 March 2010 Draft Five-Year Review Recommendation Page 2 of 3 Various Sites 248 E. Park Street, Stockton, CA, Claim Number 1695: You concurred with the EHD directive to conduct a dual phase extraction (DPE) pilot test; a work plan for such is due June 7, 2010. 517 E. Fremont Street, Stockton, CA, Claim Number 14349: You concurred with the EHD directive to submit a work plan to conduct a soil vapor extraction (SVE) pilot test. The results from a recent DPE pilot test were interpreted to show DPE would not be effective. By letter dated March 9, 2010, the EHD approved an SVE/IAS pilot test. The sparge wells are scheduled for installation in May 2010. 15615 Seventh Street, Lathrup, CA, Claim Number 367: You concur with an EHD approval by letter dated January 8, 2010, conducting an oxygen injection pilot test. The EHD approved collecting groundwater parameters needed to show that low oxygen concentrations are a limiting factor controlling natural attenuation and that injection of oxygen may be effective for enhancing natural attenuation. A feasibility study is pending. 11530 Eight Mile Road, Stockton, CA, Claim Number 3668: You concurred with the EHD directive to conduct ozone sparging pilot test. At this time there is an access problem for installing the sparge wells at the proposed locations are on a levee and the Reclamation District has not yet granted access. 814 Charter Way, Stockton, CA, Claim Number 6793: You recommend that the EHD consider site closure; at the time of preparation of this letter the monitoring wells on the site are being destroyed. As soon as proper disposal of investigation-derived wastes has been received, a closure letter will be issued. 5491 F Street, Banta, CA, Claim Number 889: You recommend that the EHD consider site closure. A monitoring well installed to further investigate high concentrations of total petroleum hydrocarbons quantified as motor oil (TPHmo) in a sand unit potentially contributing to a nearby domestic well has been installed and monitored twice; the results of the second monitoring event are still pending. The SVE system and ozone injection system have been offline for several months and rebound testing is in progress. Assuming favorable results from the groundwater monitoring and rebound monitoring, the EHD will most likely start the closure process. 620 W. Charter Way, Stockton, CA, Claim Number 4954: In 2008 and 2009, you recommended implementation or enhancement of groundwater remediation in the deeper zones on the site, generally deeper than 50 feet below surface grade (bsg); to date remediation of deeper groundwater has not been implemented. This year you recommend consideration of the site for closure. In response to free product encountered in shallow monitoring well MW15-50 in January 2009 and high concentrations of total petroleum hydrocarbons quantified as gasoline 5-Year Reviews for March 2010 Comment Letter 0410.doc