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f <br /> CLEARWATER <br /> G R Q U P, I N C <br /> Environme» 9) services <br /> June 5, 1996 <br /> Ms. Mary Meays <br /> San Joaquin County Public Health Services <br /> Environmental Health Department <br /> P. O. Box 388 <br /> Stockton, CA 95201-0388 <br /> Re: Ruiz Grocery., 4491 Durham Ferry Road, Tracy <br /> Dear Ms. Meays, . <br /> This letter responds to the points noted in,your letter dated May 23, 1996. Your letter <br /> was written with regard to the Problem.Assessment Report, Feasibility Study, and <br /> Remedial Action Plan submitted to you ron February 21,1996. The responses in this <br /> transmittal are provided in order of relative pertinence for purposes of clarity and to <br /> help involved parties move this project forward as efficiently as possible. <br /> Remedial Action Plan <br /> The PHS/EHD concurs with the concept "to use air spargingwith vapor extraction". <br /> Several other .issues were identified in the May .23 letter regarding the feasibility t <br /> study and conceptual plan for remedial action. 'These issues are listed as follows: <br /> • "PHS/EHD does not agree that a two recovery well extraction system is necessary <br /> to remove the relatively small volumes of free product which are observed in <br /> MW-1." <br /> • "The only method evaluated for free. product removal from MW71 - was <br /> groundwater extraction, with another recovery well required. Passive.skimmers <br /> have been very successful to remove the volumes of free product which have <br /> k been typically observed, i.e. .03.feet." . <br /> • "Groundwater extraction may improve the [soil. vapor extraction] radius that <br /> may be achieved; however, the added costs may not justify its application over <br /> additional soil vapor extraction wells. '_-, <br /> 1. S <br /> PHS/EHD has requested the submittal of an "alternate conceptualized design plan". <br /> While ahe PHS/EHD comments do not directly indicate the preferred alternative, it <br /> appears as if a system including a single groundwater extraction well with additional <br /> soil vapor extraction wells and air sparging is considered a more suitable application <br /> for this site. The PHS/EHD states that passive product skimmers would be useful <br />+ for the recovery of floating product from MW-1, however they do not indicate how <br />{ such a product recovery device could be effectively incorporated into the alternate <br /> design plan. <br />