ARCHIVED REPORTS_SEPARATE PHASE HYDROCARBON INVESTIGATION UNOCAL EXTRACTION WELL PILOT STUDY 2011

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Stantec Report of Findings for the Waterfront Towers Separate Phase Hydrocarbon Investigation and Unocal Extraction Well Pilot Study Waterfront Towers Parking Lot March 4, 2011 were not calculated individually because those laboratory results were all non-detect and are also assumed to be incorporated within the TPHg results as part of the applicable carbon range. During TPE on GWE-1, approximately 3.96 lbs of TPHg were removed by SVE. The removal rate was approximately 4.03 lbs/day. Calculations of mass removal by SVE are presented in Table 6. During TPE on GWE-1, the removal of chemical constituents is not directly calculated because groundwater analytical samples were not collected during TPE and also due to low groundwater production and flow rates. During the majority of the TPE test on GWE-1, the stinger tube orifice was lowered into the well casing approximately 13 feet bgs, which was approximately the level of the air/water interface inside the well. On November 19, 2010, during a short period of additional runtime, the stinger tube orifice was lowered to the bottom of the well casing which could have the effect of increasing groundwater production. Lowering the stinger tube orifice farther for the majority of the test was not possible because of the high soil vapor flow rates at very low applied casing vacuum and stinger tube vacuum. The low applied vacuum was not sufficient to simultaneously entrain substantial quantities of groundwater along with the soil vapors. Raising vapor flow rates in an attempt to increase casing vacuum and entrain more groundwater corresponded to increased chemical mass in the soil vapors, based on FID results. . The rich fuel/air mixture caused a corresponding increase in oxidizer temperatures approaching unsafe and/or inadequate % destruction levels which are evident in the oxidizer temperatures presented in Table 2. The fact that the burner temperature was maintained higher than the stack temperature indicates that % destruction maintained was adequate and that fuels had fully combusted prior to discharge. Presentation of groundwater chemical constituent total removal and removal rates are reserved for the GWE test data and results sections below, where the information collected is more viable and meaningful for such an analysis. 4.10 GWE-2 TWO-PHASE EXTRACTION TESTS DATA AND RESULTS GWE-2 was operated in the TPE mode continuously for approximately 23 hours from November 18 through 19, 2010. Field notes are included in Appendix H. The following is a summary of the data collected during the test. FID soil vapor concentration readings ranged from 1,206.0 ppmv near the start of the test to 295.0 ppmv at the end of the test (Table 2). Laboratory analysis indicated influent soil vapor concentrations of TPHg ranging from 52 to 86 ppmv. Field and laboratory analytical results are included in Table 2 and Table 4. Laboratory analytical reports and chain of custody documentation are included in Appendix I. Well field flow from monitoring GWE-2 ranged from 78 scfm at 15.7 in. H2O applied casing vacuum gauge pressure to 148.9 scfm at 16.2 in. H2O applied casing vacuum gauge pressure. Well field flow rates and applied casing vacuum data are shown on Table 2. 4.12