SITE INFORMATION AND CORRESPONDENCE_FILE 1

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s ENVIRONMENTAL HEALTH DEPARTMENT SAN JOAQUIN COUNTY ' r-tea--u •G Unit Supervisors c :? Donna K.Heran,R.E.H.S. P : < �� Director 304 East Weber Avenue, Third Floor Carl Borgman,R.E.H.S. U): Mike Huggins,R.E.H.S.,R.D.I.• Al Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. • �q .. .......��P Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. <<FoLaurie A.Cotulla,R.E.H.S. Program Manager Fax: (209) 464-0138 Robert McClellon,R.E.H.S. Mark Barcellos,R.E.H.S. JERRY MOORE MOORE PETROLEUM MAY '. 42 2004 976 W MARIPOSA AVE STOCKTON CA 95204 RE: Work Plan for Ozone Sparging And Workplan for a Limited Subsurface Site Investigation 5491 F Street Banta CA 95304 San Joaquin County Environmental Health Department (EHD) has received and reviewed Addendum to Workplan for Ozone Sparging (AWP) and Workplan for a Limited Subsurface Site Investigation (WPSSI), both dated 14 January 2004 and prepared by Apex Envirotech, Inc. (AEI). Both documents were prepared in response to EHD directives issued by letter dated 10 November 2003. The site has been under soil vapor extraction (SVE) remediation off and on since 1995. To date, an estimated 4,369 pounds of hydrocarbons have been removed from the vadose zone with the current remediation system. Dissolved contaminant concentrations have not responded as well as was expected, therefore AEI prepared a work plan dated 26 September 2003 to enhance the SVE system by adding an ozone sparging system to breakdown dissolved hydrocarbons and other fuel components. EHD requested justification of the proposed locations and depths of the ozone sparge wells. The AWP provides a model of a 25-foot radius of influence for the sparge points set at a depth of 10 feet below ground water level at an air pressure of approximately 27 pounds per square inch. Therefore the sparge points are to be set at approximately 25 feet bsg, which is approximately 10 to 12 feet below the ground water. The model is based on a uniform coarse sand as the soil media. The site-specific general lithology in the shallow zone is commonly sand from 10 to 20 feet bsg, with silt more commonly at the target depth. The number and spacing of the ozone sparge points are situated to address impacted ground water and capillary fringe zone in the areas of highest impact and along the down-gradient margin of the site. EHD approves the ozone sparging work plan as modified by the addendum. Please submit an application for a drilling permit and the $89.00 fee for each parcel to be investigated and access agreements and/or encroachment permits as appropriate.