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437 Miner Avenue <br /> Page 3 <br /> EHD has discussed the proposal for conducting slug test to assess permeability and using the <br /> data for assessment of plume fate and transport, natural attenuation, and remedial system <br /> design with the CVRWQCB. It was discussed that pump tests may provide better information <br /> for assessing permeability for these purposes. <br /> In an EHD letter dated April 29, 2005, EHD required that analysis for oxygenates continue on <br /> the water samples from U-17, U-20, U21, U-18, U26 and NP2-22. Analysis for oxygenates has <br /> continued on the water samples from all the monitoring wells. In the Conceptual Site Model <br /> ENSR recommended that analysis for MTBE and MTBE metabolites be discontinued. EHD <br /> agrees with this recommendation but noted that analysis for 1,2 DCA and EDB has not been <br /> completed. Analysis for 1,2 DCA and EDB should be performed for two quarters of sampling, if <br /> these contaminants are not detected within those two quarters, then analysis for them can also <br /> be discontinued. <br /> A work plan to install additional monitoring wells and perform permeability tests should be <br /> submitted by June 1, 2006. An evaluation of the source area soil contamination as a further <br /> groundwater contaminant source and as a potential vapor intrusion source for future buildings <br /> should be included in the work plan. If more data is required to address these issues, a <br /> proposal for obtaining the data should be included in the work plan. <br /> If you have any questions contact me at (209) 468-3449. <br /> Donna Heran, REHS, Director <br /> Environmental Health Department <br /> - C,V�lz� . a <br /> Margaret Lagorio, Supervising REHS <br /> Unit IV <br /> c: Jim Barton — CVRWQCB <br /> David Irey—SJCADA <br /> William Glenn - ENSR <br />