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PUBLICS HEALTH SERVICES <br /> SAN JOAQUIN COUN'T'Y <br /> ENVIRONMENTAL HEALTH DIVISION J. <br /> .< <br /> Karen Furst, M.D., M.P.H., Health Officer <br /> �/FORa <br /> 304 East Weber Avenue,Third Floor • Stockton, CA 95202 <br /> 209/468-3420 <br /> HAROLD & DENA KNOWLES <br /> C/O PATRICK RIDDLE <br /> 7574 SHORELINE DRIVE <br /> STOCKTON CA 95219 <br /> RE: 102 S.Wilson Way <br /> Stockton CA <br /> WORKPLAN: Work Plan for Additional Site Activities DATED: 10/31/01 <br /> PREPARED BY: Ground Zero Analysis Inc <br /> APPROVED <br /> DISAPPROVED X <br /> ADDENDUM X Submit by: February 15 2002 <br /> COMMENTS and REASONS FOR DISAPPROVAL OF THE WORKPLAN (H&S 25299.37,subd.(C)(3).): <br /> 1. The work plan proposes destroying NIW13 by filling the well casing with cement grout and applying <br /> pressure. NfW-13 is in an area of known contamination. Pursuant to SanJoaquin County Well <br /> Standards,it must be destroyed by over drilling and removing all material within the original borehole <br /> (casing and filter pack) and filled with a cement slurry. <br /> 2. The work plan recommends removal of the vapor extraction system from this site. San Joaquin <br /> County Environmental Health Department(EHD)discussed this with the Central Valley Regional <br /> Water Quality Control Board (CVRWQCB). Although a large amount of hydrocarbons have been <br /> removed by the soil vapor extraction system,in order to show the system is no longer of any use it <br /> should be pulsed a few times over the next quarter. <br /> I. The work plan only proposed installation of one nested well,with well casings screened at 35 to 55 <br /> feet below surface grade(bsg) and 70 to 90 feet bsg. Destruction of nested wells has been <br /> problematic in this county so EHD required well clusters or use of a multi-level monitoring well <br /> casing. Water samples collected from CPT-5 had high concentration of BTEX and TPH as gasoline <br /> at 74 and 88 feet bsg. Lower concentrations of these contaminants were detected in the water at 112 <br /> feet bsg. EHD and CrRWQCB discussed that a cluster of wells or use of a multi-level monitoring <br /> well should be installed west of the proposed PbfW 15S/151)location by the tire storage area. Screen <br /> intervals for the wells should be placed at 35 to 55 feet to intersect current water levels,and at 70 to <br /> 80 feet and 105 to 115 feet to intersect silty sand zones indicated on the boring log of CPT-5 and <br /> investigate those water zones where contaminants were evidenced in the water samples from CPT-5. <br /> In addition,deep screened wells(screen intervals of 105 to 115 feet) should be installed in the area of <br /> NfWl3 and bfW12. <br /> 4. The work plan proposed installation of Oxygen Release Compound(ORC) filter socks. ORC has not <br /> shown to be effective in San Joaquin County. Since your consultant does not recommend evaluating <br /> air sparging or ground water extraction,EHD directs you to evaluate ozone injection,which has been <br /> effective in this county. <br /> 5. Please be advised that multi-level wells have been installed at 101 S.Wilson Way and duster wells <br /> have been installed at 130 S.Wilson Way. These sites are being directed to continue their <br /> investigation of contamination and remedial alternatives. EHD encourages you to work with the <br /> responsible parties and consultants for these sites in the investigation and remediation of the <br /> contamination at the sites. - <br /> DATED 1/4/02 BY Rebecca E.Sediff EHS <br /> cc: CVRWQCB—Marty Harrell <br /> GROUND ZERO ANALYSIS-Gregory P.Stahl <br /> A Division of San Joaquin County Health Care Services <br />