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T - <br /> %./ �../ <br /> San Joaquin County DIRECTOR <br /> Adu�N Donna Heran, REHS <br /> Environmental Health Department <br /> ASSISTANT DIRECTOR <br /> r' k 600 East Main Street Laurie Cotulla,REHS <br /> Stockton1 California 95202-3029 <br /> { PROGRAM COORDINATORS <br /> T - <br /> Carl Bergman,RENS <br /> C P Website: WWW.S OV.Or /ehd Margaret Lagorio,REHS <br /> Mike Huggins, REHS, RDE <br /> Q<<FORN` Phone: (209)468-3 20 Robert McCellon,REHS <br /> Fax: (209)464-0138 .left Carruesco, REHS, RDI <br /> Kasey Foley,REHS <br /> CARL NAVARRA AUG 0 2 2607 <br /> 475 BLEWETT ROAD <br /> TRACY CA 95376 <br /> RE: Navarra Property Site Code: 1392 <br /> 7500 Eleventh Street <br /> Tracy CA 95376 <br /> The San Joaquin County Environmental Health Department (EHD) has received and reviewed <br /> Corrective Action Plan for Former Fueling Station, 7500 West Eleventh Street, Tracy, California <br /> (CAP), dated 25 July 2007, prepared by The San Joaquin Company, Inc. (TSJCI). <br /> In the CAP, TSJCI presented the current hydrogeoiogical model and characterization for the site <br /> and compared three remedial alternatives for addressing impacted groundwater and soil on the <br /> site north of Eleventh Street (7501 W. Eleventh Street), where the highest contaminant <br /> concentrations and light, non-aqueous phase liquid (LNAPL) hydrocarbons have been <br /> encountered. The three remedial alternatives compared included: <br /> • Skimming LNAPL from three extraction wells; <br /> Pumping LNAPL from three extraction wells into a vacuum truck; and <br /> • Utilizing an extraction trench with high-volume pumping of LNAPL into a vacuum truck. <br /> TSJCI compared the potential technical effectiveness and relative costs of the three potential <br /> remedial methods and recommended use of the extraction trench alternative as the most <br /> technologically feasible and cost effective method. The EHD requires a bit more information to <br /> demonstrate the adequacy of the recommended remedial method prior to approving or <br /> disapproving it. Submit a CAP addendum to the EHD by 17 September 2007 that addresses the <br /> following issues: <br /> • An updated LNAPL volume or mass estimate and the estimated portion that will be <br /> addressed by the proposed extraction trench; <br /> • The mass of dissolved and sorbed contaminants and the portion that will be addressed <br /> by the extraction trench; <br /> • The optimal contaminant mass to be removed to enable natural attenuation to complete <br /> the remedial action in an acceptable time period. <br /> Previously, TSJCI had estimated that between 1,000 and 8,000 gallons of LNAPL were <br /> impacting the soil and groundwater in the area of concern; this estimate has not been updated <br /> since installation of the free product monitoring wells. An important justification for the proposed <br /> method would be to effectively address the remaining LNAPL in the area, hence the question - <br /> how much is there and how much can be recovered? <br />