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ENVIRONMENTAL HEAL <br /> TtI DEPARTMENT <br /> Pp.U l fy <br /> SAN JOAQUIN COUNTY <br /> a: ?� Donna K Heran,R.E.H.S. Unit Supervisors <br /> 304 East Weber Avenue, Third Floor Carl Borgman,R.E.H.S. <br /> aTF Director <br /> Al Olsen,R.E.H.S. Stockton, California 95202-2708 Mike Huggins,R.E.H.S.,R.D.I. <br /> F60*14 Program Manager Telephone:hone: (209) 468-3420 Douglas W.Wilson,R.E.H.S. <br /> Laurie A.Cotulla,R.E.H.S. Margaret Lagorio,R.E.H.S. <br /> Program Manager Fax: (209) 464-0138 Robert McClellon,R.E.H.S. <br /> Mark Barcellos,R.E.H.S. <br /> JERRY MOORE DEC 3 n 2003 <br /> MOORE PETROLEUM <br /> PO Box 67 <br /> BANTA CA 95304 <br /> RE: Work Plan for Ozone Sparging Site Code: 1502 <br /> 5491 F Street <br /> Banta CA 95304 <br /> San Joaquin County Environmental Health Department (EHD) has received and <br /> reviewed Work Plan for Ozone Sparging (WP), dated 26 September 2003, <br /> prepared by Apex Envirotech, Inc. (AEI). The site has been under soil vapor <br /> extraction (SVE) remediation off and on since 1995. To date, approximately <br /> 4,369 pounds of hydrocarbons have been removed from the vadose zone with <br /> the current remediation system. Contaminant concentrations in ground water.has <br /> not responded as well as was expected, therefore AEI proposes to enhance the <br /> SVE system by adding an ozone sparging system to breakdown dissolved <br /> hydrocarbons and other fuel components. <br /> To better evaluate this WP, EHD reviewed various quarterly reports, boring logs, <br /> and previous directives to characterize the site status. The subsurface of the site <br /> appears to consist predominantly of silt and minor clay at 5 feet bsg; primarily of <br /> sand at 10, 15 and 20 feet bsg; and more commonly silt and/or clay, and less <br /> commonly sand at 25 feet bsg. Limited data suggest that sand occurs between <br /> 30 and 40 feet bsg. The thick sand sequences are suggestive of deposition in or <br /> near a former stream channel. The fine grained soil at 25 feet below surface <br /> grade (bsg) does not appear to be an effective barrier to vertical migration of <br /> dissolved contaminants as sand occurs locally at that depth. <br /> The vertical extent of impacted soil appears to be reasonably delineated. Data <br /> reviewed by EHD is too limited to determine if the lateral extent of impacted soil <br /> has been delineated, but most of the impacted soil appears to occur at 10 feet <br /> bsg in the data reviewed, suggesting smear zone contamination on the capillary <br /> fringe. <br /> Ground water occurs at approximately 11 feet bsg and the depth to water has <br /> varied by only a few feet since monitoring began on the site (circa 1988). Ground <br /> water flows predominantly toward the northeast, on occasion varying toward the <br />