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Stantec <br /> Report of Findings for the Waterfront Towers Separate Phase Hydrocarbon Investigation <br /> and Unocal Extraction Well Pilot Study <br /> Waterfront Towers Parking Lot <br /> March 4, 2011 <br /> 5.0 Recommendations <br /> Based on the findings of this investigation, residual hydrocarbon impacts remain in deeper <br /> groundwater zones beneath the Waterfront Towers parking facility. These data are consistent <br /> with groundwater data collected as part of the quarterly monitoring and sampling program for <br /> the site. Currently, Stantec is conducting routine SPH removal events by overpurging select <br /> wells at the Waterfront Towers parking facility. These removal events should continue and <br /> other technologies should be identified to address the residual impacts, specifically SPH found <br /> at multiple depths beneath the site. <br /> While it is understood that the SRDA has assumed responsibility for the remediation of the <br /> UOU, Stantec was directed by the L&M OU Group to conduct a pump test and feasibility study <br /> at the groundwater extraction trench previously installed by T&R for the SRDA, in response to a <br /> request by CRWQCB-CVR staff. Based on data from the pump test and feasibility study, tie-in <br /> of extraction wells GWE-1 and GWE-2 to the existing L&M OU remediation system in a DPE <br /> configuration is feasible with modifications to the existing treatment system. In addition, if the <br /> SRDA plans to treat groundwater beneath the UOU through a separate treatment system, <br /> Stantec can provide additional detailed recommendations for system design. In either case, <br /> prior to tie-in or construction of such system, a work plan to perform bench and/or pilot tests to <br /> analyze options for TBA treatment in greater depth should be implemented in order to <br /> demonstrate feasibility. Once the proper TBA treatment system has been tested and approved; <br /> Stantec will move forward with the proper permitting and system installation components to <br /> properly mitigate TBA concurrently with VOCs leaching into the GCT. <br /> 5.15 <br />