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 from GWE-2 may have temporarily inhibited full recovery of groundwater levels in GWE-1 following its respective pump test. On November 16, 2010 at 5:20 pm, following 4.83 hours of GWE to 1,564 gallons total production, the submersible pump was shut down for adjustments due to diminished groundwater yield. Recharge was measured within 15.2 hours and groundwater levels had rebounded from 14.97 to 14.01 feet bgs. Restart on November 17 at 8:53 am was followed by 1.42 hours of GWE to 2,041 gallons total production (additional 477 gallons). The submersible pump was then shut down due to low groundwater production. Recharge was measured within just over 14 minutes and groundwater levels had rebounded from 15.10 to 14.47 feet bgs. GWE-2 was never restarted again. During GWE on GWE-2, the following selected chemical constituent mass was removed: • Approximately 1.2E-3 lbs of TBA was removed at a removal rate of 9.7E-3 lbs/day. At <4.0 gpm that is a projected removal rate of less than 3.5E-3 lbs/day. GWE analytical data are presented in Table 5 and calculations of mass removal by GWE are presented in Table 7. Laboratory analytical reports and chain-of-custody documentation are • included in Appendix I. 4.8 TWO-PHASE EXTRACTION TESTS PROCEDURE An existing TPE system was employed to extract groundwater and soil vapors from the GWE wells independently. The test equipment configuration consisted of: • Vapor treatment system (thermal oxidizer) • 25-hp liquid ring vacuum blower capable of approximately 400 cubic feet per minute flow and 25 in-Hg applied gauge vacuum • Air/water separator tanks • Vapor/water extraction manifolds • Flow totalizer installed on the discharge side of the air/water separator tanks • 18,000-gallon plus storage tank with secondary containment • Miscellaneous fittings, meters, and equipment In order to extract groundwater and soil vapors from the recovery wells, a 1-1/2" diameter stinger tube was lowered into each well casing, the well casing was sealed, and groundwater/soil vapors were recovered simultaneously via applied vacuum pressure from the vacuum blower through the stinger tube. The TPE wellhead, manifold, and headers were outfitted with appropriate fittings for vapor sampling and water/soil vapor flow measurement. The following data were recorded for each GWE well at appropriate intervals: • Groundwater elevations (measured and recorded prior to initiation) 4.10