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ll ] <br /> V <br /> Ms. Vicki McCartney Project No.: 880:040.1A.0110 <br /> May 23, 2003 <br /> Page 3 <br /> The gradient has ranged between 0.001 and 0.002. Appendix B includes a rose diagram <br /> i <br /> showing flow directions and gradients. <br /> WELL SURVEY <br /> A search for domestic, municipal,agricultural and industrial wells within a 2,000-foot <br /> radius of the site was conducted by IT in May 2002. The Department of Water <br /> Resources was contacted as well as other municipal water suppliers. The well search <br /> indicated that there was one Caltrans irrigation well located within a 2,000-foot radius of <br /> the site. The California Department of Transportation (Caltrans) irrigation well was <br /> located at the 1-5 overpass. Based on conversations with Ms. Carol Oz from the <br /> San Joaquin County Public Health Services,Environmental Health Department the well <br /> was abandoned as part of the construction of the new I-5 on and off ramps, and is no <br /> longer a potential receptor or a vertical conduit. <br /> REMEDIAL ACTIVITIES <br /> Excavation <br /> During product line and dispenser upgrades performed in June 2000 by IT, <br /> approximately 262 tons of petroleum-impacted soil was excavated from below the fuel <br /> dispensers and product lines. The impacted soil was transported to the Forward Landfill <br /> in Manteca, California, for disposal. The majority of petroleum-impacted soil was <br /> removed due to the over-excavation of the impacted locations. <br /> Dual Phase Extraction Test <br /> From June 10 through 15, 2002, Shaw contracted TRC Alton Geoscience, Inc. to <br /> conduct a five day pilot dual-phase extraction (DPE) test. The DPE test was conducted <br /> by simultaneously extracting soil vapor and groundwater from well MW-1. During-the.- <br /> test <br /> uring the.test a total of 19,700 gallons of groundwater were pumped from well MW-1 at an <br /> average rate of 2.74 gallons/minute. Depth to water was monitored in wells MW-2 <br /> through MW-5 throughout the test. The average drawdown ranged between 0.13 and <br /> 0.22 feet. Prior to the DPE test, TPHg, benzene, and MtBE concentrations in well <br /> MW-1 were 4,900, 1,000, and 17,000 micrograms per liter (µg/L), respectively. i <br /> SHAW ENVIRONMENTAL,INC. <br /> NAsacDP\2003\Prj\880\8800401 A.3 ac.doc " <br />