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i <br /> Mr. Frank Ryan Page 2 <br /> j <br /> In order to complete the corrective action plan you need to perform a feasibility study. The feasibility study shall <br /> evaluate two alternative treatment methodologies for removing the existing contamination from the soil and <br /> groundwater beneath this site. PHSIEHD recommends that the feasibility study test in situ methods such as vapor <br /> extraction/air sparging, biosparging or bioventing. <br /> The feasibility study should compile data which will enable a comparison of the cost of implementing each system. 4 <br /> The study should evaluate technological parameters of the treatment technologies and the subsurface environment. <br /> Data that should be collected for evaluation for each treatment technology should include; radius of influence and <br /> flow rates of injection and extraction wells, ability of the technology to reach cleanup levels, the rate of removal <br /> of contaminants, soil permeability, contaminant vapor pressure and Henry's law constant, monitoring and testing i <br /> regimens, soil pH, moisture content, carbon:nitrogen:phosphorous ratio, is groundwater depression necessary for <br /> effective treatment, dissolved oxygen levels, heterotrophic bacteria count CFU/gram of dry soil, and any other. <br /> applicable parameter. <br /> PHSIEHD does not recommend installation of pump and treat systems as a remediation technology. It has been <br /> well documented that these systems are effective in removing a great volume of water, but only a small and <br /> insignificant mass of hydrocarbons. This alternative treatment technology is also very expensive to install and <br /> operate. These statements are based on results of remedial effectiveness of pump and treat at underground storage <br /> tank sites within San Joaquin County and other locations in the state of California. The use of this technology is <br /> limited to obtaining hydraulic control over migrating plumes, or to depress the water table to facilitate other <br /> remedial options. In order to use this technology as the primary treatment of soil and groundwater contamination <br /> at this site, it must be evaluated as part of the feasibility study, and demonstrated to be the best available treatment <br /> technology. <br /> PHSIEHD requires you to submit,a work plan for installation of pilot test systems, to evaluate the two treatment <br /> technologies selected for the feasibility study, by December 30, 1995. <br /> For further information, please contact Steven Sasson at (209) 468-3459. <br /> Donna Heran, RENS, Director <br /> Environmental Health Division <br /> Steven Sasson, Senior REHS Diane M_ Hinson, REHS <br /> Site Mitigation Unit Supervisor <br /> SS <br /> cc: Elizabeth Thayer, CVRWQCB <br /> Annabelle Mackey, SWRCB <br /> Lee Delano, WHF, Inc. <br /> F <br /> i <br /> t <br /> �i: i <br />