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 • Hour meter readings from the vacuum blower and/or the time for each measurement/sample interval • Depth of the stinger tube orifice • Applied wellhead vacuum levels in the sealed GWE well casings • Stinger tube vacuum at the point of entry to the TPE wellheads • Manifold vacuum • Blower vacuum • Soil vapor oxidizer combustion chamber and discharge stack temperatures • Extracted vapor flow rates • Total groundwater flow rate • Influent vapor samples were collected and analyzed for soil vapor concentrations with a flame ionization detector (FID) meter • Groundwater elevations (measured after the equipment was shutdown at the end of each test) 4.9 GWE-1 TPE TESTS DATA AND RESULTS GWE-1 was operated in the TPE mode continuously for approximately 22.5 hours from November 17 through 18, 2010. GWE-1 was operated again for approximately 15 minutes on November 19, 2010 to lower the stinger tube to the bottom of the well and fully dewater it. The following is a summary of the data collected during the test. FID soil vapor concentration readings ranged from 50,000 parts per million by volume (ppmv) near the start of the test to 333.1 ppmv at the end of the test (Table 2). Laboratory analysis indicated influent soil vapor concentrations of TPHg ranging from 58 to 130 ppmv. Field and laboratory analytical results are included in Table 4 and Table 6. Laboratory analytical reports and chain of custody documentation are included in Appendix I. Well field flow from GWE-1 ranged from 98.7 standard cubic feet per minute (scfm) at 0.8 inches of water (in. H2O) applied casing vacuum gauge pressure to 174.0 scfm at 1.2 in. H2O applied casing vacuum gauge pressure. The value of the casing vacuum gauge pressure of 0.8 in. H2O was assumed from the next lowest flow rate (107.1 scfm) due to the inadvertent omission of the casing vacuum measurement at the 98.7 scfm measurement. Well field flow rates and applied casing vacuum data are shown on Table 2. The average GWE rate for GWE-1 was negligible as only 22.5 gallons of groundwater were recorded as removed from the well during TPE testing which would be <0.02 gpm. Groundwater extraction data can be viewed in Table 2. The total mass of TPHg removed during the pilot test from soil vapor was estimated using analytical results for TPHg as hexane, mass flow rates, and system runtime. Similar calculations based on FID readings as hexane were not completed because of the scale of the difference between laboratory results and FID measurements. Other chemical constituents such as BTEX 4.11