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 GCT towards GWE-1 and then down to GWE-2 and eventually south toward the Mormon Slough. The GWE test results show higher sustained groundwater recovery from GWE-2 than GWE-1, which is likely because GWE-2 is located near the bottom of the GCT. Groundwater recovery rates observed in GWE-1 and GWE-2 are similar and not higher than groundwater flow rates observed in other four-inch diameter nearby wells historically tested on the L&M OU site. The projected design groundwater flow rates and pressures are as follows: • Design of pumping groundwater from GWE-1 should anticipate peak flows of at least 7.0 gpm and sustained flows of around <2.0 gpm. Head pressure against any pump installed in GWE-1 would be approximately 15 feet of water plus additional head losses from pipe and pipe components. • Design of pumping groundwater from GWE-2 should anticipate peak flows of at least 6.3 gpm and sustained flows of around <4.0 gpm. Head pressure against any pump installed in GWE-2 would be approximately 15 feet of water plus additional head losses from pipe and pipe components. • Combined groundwater recovery system and treatment system should anticipate peak groundwater flows of approximately 13.32 gpm with sustained flows of less than six gpm from GWE-1 and GWE-2 combined. Note that TPE testing (which followed pump testing) indicates that groundwater production was substantially reduced following the pump test portion of these tests. This indicates that higher flows during the pump test portion may have consisted of storage in the UOU excavation and GCT and is not representative of long term groundwater production, which may be substantially reduced. Combined groundwater treatment system should take into account total hydrocarbon loadings. Soil vapor extraction from GWE-1 and GWE-2 should be initiated because those activities may help to recover chemical mass from the UOU and maintain the cleanliness of fill material placed there by the SRDA following excavation activities. The projected design SVE flow rates and pressures are as follows: • Design of SVE from GWE-1 should anticipate peak vapor flows of around 174 scfm. Applied casing vacuum would have to be at least 1.3 in. H2O gauge vacuum pressure plus additional head losses from pipe and pipe components. • Design of SVE from GWE-2 should anticipate peak vapor flows of around 148.9 scfm. Applied casing vacuum would have to be at least 16.2 in. H2O gauge vacuum pressure plus additional head losses from pipe and pipe components. Combined SVE recovery and vapor abatement systems for GWE-1 and GWE-2 should anticipate peak flows of approximately 400 scfm and be capable of generating the 400 scfm at a minimum of 16.2 in H2O gauge vacuum pressure 4.14