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q San Joaquin County DIRECTOR <br /> v N „ Donna Horan, REHS <br /> oP. . . . . , . . . Environmental Health Department <br /> �. • '_ - ' .O M ASSISTANT DIRECTOR <br /> Q. r•. '2� 600 East Main Street Laurie Corolla, REHS <br /> �i (•}gjl( - ' - � Stockton , California 95202-3029 PROGRAM COORDINATORS <br /> Carl Borgman, REHS <br /> Mike Huggins, <br /> Cq�IFo.R NSF Website: www.sjgov.org/ehd MargaretLagorioE REHSDI <br /> Phone: (209) 468-3420 Robert McClellon, REHS <br /> Fax: (209) 464-0138 Jeff Carruesco, REHS, RDI <br /> Kasey Foley, REHS <br /> FLOYD BARNES AUG 15 2DD7 <br /> 9477 FOUNTAIN VALLEY <br /> STOCKTON CA 95209 <br /> RE : Barnes Trucking SITE CODE : 2506 <br /> 1817 Fresno Avenue <br /> Stockton CA 95206 <br /> San Joaquin County Environmental Health Department (SJC/EHD) has reviewed First <br /> Quarter 2007 Groundwater Monitoring and iSOC Remediation Activity Report (Report) <br /> dated April 23, 2007 submitted on your behalf by Clearwater Group (Clearwater) and has <br /> the following comments. <br /> The Report documents groundwater monitoring and sampling and remediation system <br /> maintenance activities that were conducted_ at your site during first quarter 2007. The <br /> iSOC remediation system began operation in August 2004. In October 2006 a <br /> construction project on the east side of Fresno Avenue dewatered the subsurface directly <br /> across the street from your site in order to install underground utilities . In the two <br /> groundwater monitoring and sampling events following the dewatering project, there were <br /> no reported detections of petroleum hydrocarbon contamination in groundwater <br /> monitoring well MW-5B , which previously had been the well with the highest reported <br /> concentrations-of--contaminants- on-your-site. - <br /> SJC/EHD has reviewed 2nd quarter 2007 analytical data submitted to Geotracker. For the <br /> first time in three quarters well MW-513 reported detections of all constituents analyze <br /> except for methyl tertiary butyl ether, though at much reduced concentrations from prior to <br /> the subsurface dewatering. Total petroleum hydrocarbons as gasoline (TPHg) was <br /> reported at 290 micrograms per liter (pg/I), compared with 17, 000 µg/I before the event. <br /> In the Report Clearwater recommends preparation of a work plan to conduct further <br /> subsurface investigation east of your site to determine if the dewatering project has <br /> moved the core of your plume offsite. The dewatering project, which lasted for a couple of <br /> weeks , extracted a large volume of groundwater to surface ponds. The water was then <br /> pumped from the ponds into spray trucks and sprayed over the surface of the construction <br /> project for dust control. If contaminated water was pulled from the Barnes Trucking site <br /> by the dewatering pumps, it may have been removed from the subsurface. Monitoring <br /> wells MW-7 and MW-8 , which were located to be down gradient from MW-5B, but are <br /> somewhat oblique to the possible flow path between MW-513 and the groundwater <br /> extraction trench , have not shown an increase in contaminant concentrations since the <br /> inadvertent "remediation" by groundwater extraction occurred . SJC/EHD would approve a <br /> work plan for collection of a grab groundwater sample directly east of the Barnes Trucking <br /> facility to assess for the remnant plume. SJC/EHD recommends utilizing direct push <br /> technology for such an investigation . <br />