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w San Joaquin County DIRECTOR <br /> our N Donna Heran, REHS <br /> O, .P " ' • r0 Environmental Health Department ASSISTANT DIRECTOR <br /> 600 East Main Street Laurie Cotulla, REHS <br /> U): Stockton , California 95202-3029 <br /> PROGRAM COORDINATORS <br /> Carl Borgman, REHS <br /> • •C4� .���P Website: wwwsjgov. org/ehd Mike Huggins, REHS, RDI <br /> FOR Margaret Lagorio, REHS <br /> Phone: 209 <br /> ( ) 468-3420 Robert McClellon, REHS <br /> Fax: (209) 464-0138 Jeff Carruesco, REHS, RDI <br /> Kasey Foley, REHS <br /> RAYMOND FARMER SEP 2 5 2007 <br /> BESS FARMER <br /> 3810 FOURTEEN MILE DRIVE <br /> STOCKTON, CA 95219 <br /> RE: TOYOTA TOWN SITE CODE: 1151 <br /> 610 HUNTER ST <br /> STOCKTON CA 95202 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed the <br /> Recommendation for Remediation System Modification dated April 6, 2006 prepared by your <br /> consultant ATC Associates Inc . (ATC). ATC recommends the use of ozone sparging as the <br /> technology of choice for site remediation. EHD directs that a feasibility study for ozone treatment <br /> be submitted. ATC should determine that site and contaminant characteristics are favorable to <br /> ozonation. If ozonation is found to be feasible, a workplan for a bench-scale test or other method <br /> for acquiring sufficient data for the Central Valley Regional Water Quality Control Board <br /> (CVRWQCB) to evaluate Waste Discharge Requirements (WDRs) should be submitted. <br /> CVRWQCB will determine whether or not issuing WDRs is appropriate. The bench-scale test <br /> should conform to Interstate Technology & Regulatory Council (ITRC) guidance. <br /> Please note that the EHD does not concur with the implied 70 % contaminant mass reduction as <br /> the clean up goal for your site. Site closure, or a "no further action" (NFA) status is given after <br /> the contaminant release has been shown to pose minimal risk to human health, the environment <br /> and ground water, the contaminant plume has been well defined, shown to be contracting, and the <br /> projected time-frame for a return to background conditions has been well demonstrated. Also note <br /> that the calculations demonstrating a 70 % reduction of contaminant mass through ozonation in 3 <br /> years is an optimistic scenario, it assumes that every molecule of ozone generated will react with <br /> the target contaminants. This is highly unlikely as it is quite probable that there will .be many <br /> other competing reactions that well take place in the subsurface. <br /> EHD directs you to evaluate the existing SVE system operation for addressing impacted soil and <br /> submit a recommendation for reinitiation, modification, or cessation of its operation. Your <br /> consultant should also make a recommendation concerning confirmation borings if SVE appears <br /> to have reached its practical limit. <br /> Please feel free to contact Frank Girardi at (209) 953,0 if you have any questions. <br /> Donna Heran, REHS, Director <br /> Environmental ly Department <br /> Frank Girardi, Senior REHS Nuel C. Henderson, Jr., PG <br /> LOP/Site Mitigation Unit IV LOP/Site Mitigation Unit IV <br /> cc: Jcanne Homsey - ATC <br /> cc: RWQCB, Central Valley Region — James L. L. Barton, PG <br />