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DRAFT Geosyntec <br /> consultants <br /> mentioned constituents. Soil sampling locations and analytical results are summarized in Section <br /> 3.1.5 and discussed in detail in ERS's UST 817B and UST 916E Site Characterization Report <br /> (ERS, 2008). <br /> 3.1.3 1999- 2000 Investigation <br /> In September 1999, the Navy advanced 11 additional borings at the UST 817B Site to depths of <br /> approximately 21 to 36 feet bgs. In addition, the Navy installed eight additional monitoring wells <br /> (917-7 through 917-14) in October 1998. Thirteen soil and 14 grab ground water samples were <br /> collected and analyzed for BTEX, TPHg TPHd, TPHmo, MTBE, oil and grease, and soluble and <br /> total lead. In addition, the Navy also continued to conduct groundwater monitoring to evaluate <br /> the concentrations of the constituents in groundwater. Soil sampling locations and analytical <br /> results are summarized in Section 3.1.5 and discussed in detail in Tetra Tech's Building 817-B <br /> Underground Storage Tank Site Investigation Report dated August 14, 2001 (Tetra Tech, 2001). <br /> The Navy concluded that the soil and groundwater contamination had been delineated and <br /> recommended several corrective action options to address the contamination including <br /> monitoring natural attenuation (MNA), enhanced MNA, and dual-phase extraction (Tetra Tech, <br /> 2001). The CVRWQCB reviewed Tetra Tech's report and indicated that the contaminant <br /> concentrations in groundwater were stable; however, the CVRWQCB did not believe that MNA <br /> was viable and suggested proceeding with enhanced MNA (CVRWQCB, 2002). <br /> 3.1.4 2008 Soil Investigation <br /> Building 817B was demolished in 2007. On March 24, 2008 and April 8, 2008, ERS conducted a <br /> series of direct-push soil borings to determine the extent of vadose zone soil contamination. A <br /> total of 24 soil borings were advanced to a depth of 8 to 12 feet. Soil samples were screened <br /> using a photoionization detector(PID) and visually observed for petroleum contamination. <br /> Readings were taken both above and below the saturated zone. All of the highest readings were <br /> from the saturated zone or immediately above it. Following the results of the PID screening, soil <br /> samples were collected from seven locations, including beneath the former fuel dispenser <br /> islands, the former vehicle wash rack, and near locations where PID results in the unsaturated <br /> zone were highest(locations 817-C3, 817-05, and 817-C9). The soil samples were analyzed for <br /> TPHg, BTEX, and MTBE. Sampling locations and analytical results are presented and discussed <br /> in ERS's UST 817E and UST 916B Site Characterization Report(ERS, 2008). Soil analytical <br /> results from locations 817-D2, 817-D3, 817-D4, 817-D5, and 817-D7 sampled during the 2008 <br /> investigation are presented in Figure 2. <br /> ERS concluded that the petroleum hydrocarbon concentrations in soil have decreased since the <br /> USTs were removed and do not pose a risk to groundwater quality and the environment, and that <br /> the institution controls set forth in the Consent Agreement require that RRI, including UST <br /> 81713, be used solely for industrial and Port related activities (ERS, 2008). The CVRWQCB <br /> reviewed ERS's report and concluded that additional characterization of the groundwater was <br /> necessary and that it would be necessary for the Port to evaluate for the potential for vapor <br /> migration to indoor air(CVRWQCB, 2010a). <br /> Draft Soil and Soil Vapor Investigation 5 August 30,2019 <br />