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<br />Ms. Lori Potter <br />October 10, 1999 <br />Page 2 <br />Inc <br />the injection point to the first nest. Two additional wells should be installed at a distance equivalent to <br />the first nest, but offset from the line formed by the injection and nested wells. <br />RMC believes that the monitoring wells need to be installed prior to the initiation of tha? Pilot Tests. Early <br />installation of wells would: (1) provide solids materials to characterize the Pink Gneissibackfill material <br />and allow performance of additional laboratory column testing; and (2) establish baseline water quality <br />for these wells, including the documentation of spatial-temporal water quality variations within the Pink <br />Gneiss Pit. <br />MONITORING PLAN <br />Paze 8. Comment No. 2.1. <br />Review of the electronic groundwater and surface water database submitted to the CDIPHE by BMRI <br />indicates that gross alpha activity is high in several monitoring wells completed in the Fink Gneiss and <br />West Pits. In addition, four samples reported for the "seep" contained gross alpha acti~lity ranging from <br />39 to 58 pCi/L. Review of the historic gross alpha data for the downstream surface watler monitoring <br />station RS-5 indicates an upward trend during 1997 and 1998 similar to that exhibited by sulfate and <br />manganese. BMRI should include radiological tests (i.e., gross alpha, gross beta) in thelir monitoring <br />program, and perform additional testing to determine the specific radionuclides responsible for the <br />elevated activity. <br />BMRI proposes to include copper in the monitor program. Aquatic standards for copp@r are hardness <br />based. Hardness is calculated using calcium and magnesium concentrations. Calciumi is included in the <br />program, but magnesium is not. RMC recommends including magnesium in the monitoring program. <br />RMC disagrees with the DMG's proposal to go from bi-weekly to monthly sampling of surface water <br />station RS-5. If anything, the frequency of surface water monitoring should be increased. <br />Paee 9. Comment No. 2.1. and Response <br />The groundwater monitoring network, as modified by the DMG and readily agreed to !by BMRI, would <br />not include any wells in the "window." RMC believes that it is necessary to include w@Ils in the window <br />area to verify that the West Pit dewatering system is performing its designed function. <br />