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San Joaquin County <br /> Environmental Health Department DIRECTOR <br /> 1868 East Hazelton Avenue Donna Heran, REFS <br /> PROGRAM COORDINATORS <br /> I�pplt Stockton, California 95205-6232 Robert McClellon, REHS <br /> Jeff Carruesco, REFS, RDI <br /> CgCr ,��P Website: www.sjgov.org/ehd Linda <br /> Foley, RENS <br /> Foa EHS <br /> Phone: 209 468-3420 Linda y Estradkatte, , RE <br /> ( ) Rodney Estrada, REHS <br /> Fax: (209) 464-0138 Adrienne Ellsaesser, REHS <br /> September 17, 2014 <br /> Ken Gillies <br /> Gillies Trucking <br /> P O Box 8303 <br /> Stockton, CA 95208 <br /> Subject: Closure Request Response <br /> Gillies Trucking LOP Site Code: 1703 <br /> 3931 Newton Road <br /> Stockton, CA 95205 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Case Closure <br /> Summary and No Further Action Request (CCS&NFAR), dated August 2014, prepared and <br /> submitted by Stephen G. Muir Consulting Geologist & Geophysicist (Muir) on your behalf. In <br /> CCS&NFAR, Muir presented a history of the site investigation and corrective actions, a conceptual <br /> site model (CSM), an evaluation of the site for case closure under the Low-threat Underground <br /> Storage Tank Closure Policy (LTCP) recently adopted by the California State Water Resources <br /> Control Board (SWRCB), an evaluation for case closure under the antecedent Appendix A — <br /> Reports Tri-Regional Board Staff Recommendations for Preliminary Investigation and Evaluation of <br /> Underground Tank Sites, published by the Central Valley Regional Water Quality Control Board <br /> (CVRWQCB), and a work plan for the proper destruction of the monitoring and remediation wells <br /> installed as part of the corrective action for your site. <br /> Muir concluded that the residual contaminant mass sorbed to soil, with no allowance made for mass <br /> loss through natural attenuation, is on the order of 43,500 pounds of total petroleum hydrocarbons <br /> quantified as diesel (TPHd); the dissolved contaminant mass is estimated to consist of 1 to 2 <br /> pounds of volatile hydrocarbons and 4 to 10 pounds of TPHd. Impacted soil extends to a depth of <br /> 80 feet below surface grade (bsg) and horizontally approximately 75 feet from the source area, <br /> locally as much as 150 feet; most of the impacted soil occurs between 45 and 65 feet bsg. <br /> Impacted groundwater locally extends vertically downward as much as 125 feet bsg and is <br /> estimated to extend on the order of 250 feet horizontally in the downgradient direction and may go <br /> off-site a short distance under the public right-of-way of Newton Road. Muir has determined though <br /> analysis of dissolved plume areal extent and concentration trends through time that the plume is <br /> contracting and decreasing in concentration and is unlikely to impact the nearest downgradient <br /> water supply well, reportedly utilized for irrigation. <br /> Your site cannot pass the LTCP criteria due to dissolved plume length and proximity of water supply <br /> wells, but does pass other general criteria and site-specific criteria for vapor intrusion hazard and <br /> human exposure to impacted soil and outdoor air. Your site generally passes the Appendix A <br /> criteria as it applies to your site. <br /> Closure Request Response Letter 0914 <br />