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ENVIRONMENTAL HEALTAEPARTMENT <br /> SAN JOAQUIN COUNTY <br /> Q Donna K.Heran,R.E.H.S. Unit Supervisors <br /> X Director 304 East Weber Avenue, Third Floor Carl Bergman,R.E.H.S. <br /> - <br /> At Olsen,R.E.H.S. Stockton, California 95202-2708 Mike Huggins,R.E.H.S.,R.D.I. <br /> =- Douglas W.Wilson,R.E.H.S. <br /> CqC/FOR�`P • Program Manager Telephone: (209)468-3420 Margaret Lagorio,R.E.H.S. <br /> Laurie A.Co R.E.H.S. Fax: (209) 464-0138 Robert McClellon,R.E.H.S. <br /> Program Manager Mark Barcellos,R.E.H.S. <br /> GEORGE AND MEI TERANISHI MAY 2 4 2005 <br /> 1600 DURHAM FERRY RD <br /> TRACY CA 95376 <br /> RE: GEORGES SERVICE Site Code: 1550 <br /> 1600 DURHAM FERRY RD <br /> TRACY CA 95376 <br /> San Joaquin County Environmental Health Department (EHD) has received and <br /> reviewed Interim Remediation Action Plan, In Situ Remediation Pilot Test (Plan), dated <br /> 21 March 2005, prepared on your behalf by your consultant Geological Technics, Inc. <br /> (GTI). The Plan proposes: 1) Installation and operation of an ozone/oxygen (03/02) <br /> injection system to remediate groundwater impacted by contaminants introduced to the <br /> subsurface through an unauthorized release of fuel hydrocarbons from an underground <br /> storage tank (UST) system formerly located on your site; and 2) Installation of a soil <br /> vapor extraction (SVE) system, utilizing vapor wells previously emplaced in the <br /> excavation backfill, to remove hydrocarbon vapor stripped from impacted groundwater <br /> that migrates into the backfill as a result of the 03/02 system operation. <br /> Although EHD agrees that ozone injection may be an effective remedial alternative for <br /> impacted groundwater at this site, EHD cannot approve the work plan as presented for <br /> the following reasons: <br /> • GTI proposes installation of eight 03/02 sparge points, only three of which are in <br /> the more intensely impacted groundwater. The four proposed points along <br /> Highway 33 are on the up-gradient side of shallow impacted groundwater and <br /> three of the four may not even be in the plume. <br /> • There are no observation wells currently located or proposed for immediately <br /> down-gradient of the proposed 03/02 injection points, especially for the three <br /> points proposed for the more intensely impacted groundwater, from which to <br /> monitor the effects of injection to evaluate effectiveness for reducing contaminant <br /> mass or to monitor for detrimental effects of concern to the Central Valley <br /> Regional Water Quality Control Board (CVRWQCB). <br /> • The necessity for installation of an SVE system to remove vapor from clean <br /> backfill has not been presented in a manner that would serve as a justification for <br /> its installation and operation. In other words, the need and efficacy for the SVE <br /> system has not been shown. The proposed 03/02 injection wells will utilize gas <br /> diffusers, which typically are used at low injection pressures and rates, such that <br /> groundwater mounding and hydrocarbon stripping are minimal effects due to <br />