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r <br /> r <br /> f - <br /> PUBLIC TiEALTH SERVICES <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION y ;{ <br /> Ernest M. Fujimoto, M?D., M.P.H., Acting Health Officer = <br /> 304 E. Weber Ave., Third Floor :+ P. O. Box 388 • Stockton, CA <br /> 21091468-3420 ED <br /> BOB DENINNO SEP12 <br /> 19% <br /> SOUTHLAND CORPORATION ' <br /> 19033 WEST VALLEY HWY St D-104 <br /> KENT WA 98032 l <br /> RE: 7-Eleven Store #20304 A, SITE CODE: 1409 <br /> 455 West Grant Line Road <br /> Tracy CA 95376 <br /> i <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has <br /> completed review of the Fluor-Daniel GTI "Work Plan for Groundwater Extraction Well <br /> Installation" dated April 12, 1996, "Addendum to Work Plan for Groundwater Extraction <br /> Well Installation" dated July 5, 1996 and the "GWE & SVE Well and Line Installation" <br /> figures dated August 12, 1996. PHS/EHD has prepared the following comments for your <br /> consideration. „d <br /> 1 r <br /> PHS/EHD requested in correspondence dated March 27, 1996 that the selected <br /> remediation methodology (pump and treaty be re-evaluated based on the then current <br /> recovery rates of less than 1 gallon per minute and the effectiveness to dewater so that an <br /> evaluation of soil vapor extraction could be initiated. The March correspondence was <br /> prepared following discussion with GTI regarding various remedial alternatives. <br /> The work plan dated April 12, 1996, included a proposal to install one 6 inch groundwater <br /> extraction well to be screened from 4 to 15 feet below ground surface (bgs) in the former <br /> location of the underground storage tanks. The well will be drilled to a total depth of 20 <br /> feet, so that the extraction pump'`can be seated at the bottom of the well. The work plan <br /> stated that two soil samples would be submitted for laboratory analysis. A north-south <br /> trench would also be installed to connect the new groundwater extraction piping to the <br /> already existing piping system. `1 <br /> 4 <br /> In May and June discussions were continued and PHS/EHD stressed that work plans <br /> should be submitted that address comments raised in discussion. It was PHS/EHD's hope <br /> that any remedial investigation necessary to evaluate remedial alternatives could be <br /> accomplished during the next field mobilization. <br /> The addendum dated July 5, 1996, included a proposal to install two 6 inch groundwater i <br /> extraction wells, constructed as proposed earlier with the second well to be installed ; <br /> approximately 10 feet west of MW10. The addendum also proposed the installation of five <br /> vaults, two of which to contain the proposed groundwater extraction wells. The three <br /> remaining vaults would be installed for potential future use. Two trenches will be <br /> constructed so that a soil vapor extraction line and screened horizontal piping can be <br /> installed for potential future use.' <br /> ;6 <br /> A Division of San Joaquin County Health Care Sen ices <br />