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DEER <br /> GWETS expansion. The model will also be used to further optimize operations of the existing <br /> Phase I IRA system and the combined Phase I and Phase III system. <br /> SPECIFIC COMMENTS <br /> COMMENT 3 <br /> LPL acknowledges the importance of aquifer testing the B-zone as proposed in the Phase III Plan, but also recommends that <br /> additional aquifer testing be conducted to assess the spatial variability in aquifer and aquitard properties between the Pacific <br /> Avenue and Inglewood Avenue areas. Data already exist on the A-zone aquifer in the vicinity of Pacific Avenue due to the <br /> previous aquifer test and the drawdown response data associated with the Phase I IRA system operations, but no A-zone <br /> aquifer test has been conducted in the Inglewood Avenue area. If significant spatial variations in aquifer-aquitard properties <br /> exist over the approximately 1000-ft distance separating Pacific Avenue and Inglewood Avenue, design decisions for the <br /> proposed Phase BI IRA might be affected. Likewise for the B-zone,the aquifer test proposed in the Phase III Plan would <br /> provide adequate information about aquifer properties in the vicinity of Inglewood Avenue, but aquifer properties might well <br /> vary significantly in space, with different properties along Pacific Avenue. <br /> RESPONSE <br /> Although LFR acknowledges the potential for spatial variability in A and B-zone aquifer properties <br /> between the Pacific and Inglewood Avenue areas, an evaluation of existing data indicates complete <br /> hydraulic capture of the A-zone groundwater with limited variability in groundwater extraction <br /> rates (from 6 to 9 gallons per minute [gpm]) in existing A-zone groundwater extraction wells along <br /> Pacific Avenue, despite lithologic variation. Based on our experience, this degree of variation is <br /> not uncommon and can be accounted for in groundwater remediation design. However, since <br /> adequate aquifer data does not exist for the B-zone, LFR proposes to perform one additional <br /> B-zone aquifer pumping test in the Inglewood Avenue area. <br /> In the proposed groundwater modeling simulations, LFR will use existing A-zone data and the <br /> newly collected data from the proposed B-zone test to evaluate optimum groundwater extraction <br /> scenarios for the combined Phase I/Phase III system. A sensitivity analysis will be performed <br /> within the modeling analysis to accommodate for potential variations in aquifer/aquitard properties <br /> in the Pacific and Inglewood Avenue areas. The proposed Phase III IRA will then be designed to <br /> accommodate these potential variations in aquifer/aquitard properties. As such, the system will be <br /> designed to compensate for potential uncertainties in groundwater extraction rates and will <br /> automatically adjust these rates in each individual well to maintain the optimal drawdown required <br /> to effectively capture groundwater affected with hazardous substances. <br /> COMMENT 4 <br /> It is unclear from the brief description in Section A4.0 whether the proposed three-dimensional groundwater flow modeling <br /> will explicitly represent the A/B aquitard. LPL believes it is important that the storage effects of the A/B aquitard be explicitly <br /> accounted for in the updated groundwater flow model to adequately simulate the processes relevant to control of groundwater <br /> flow within the contaminant plume. <br /> MAA REVISIONS-rsp-Phasalll-IRA-06752:DEH 4 <br />