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1. Diversion of the creek in a temporary pipeline to ensure that all potential sources are <br />prevented from impacting the creek while long -term remedial measures are identified and <br />implemented. The upper and lower groundwater cutoff walls, along with continued <br />pumping and treating of any residual alluvial groundwater, will prevent any offsite <br />excursions of contaminated groundwater during this period. <br />2. In -situ treatment of the mine pool to rapidly reduce concentrations and thus reduce <br />potential consequences of any potential migration of mine pool water. <br />3. Once alluvial groundwater is largely dewatered from pipeline diversion of the creek, all <br />three potential sources of impacts to water quality in Ralston Creek can be addressed as <br />follows: <br />This strategy is logical, scientifically supported, and is expected to ensure effective long -term <br />protection of water quality in Ralston Creek sooner than any other possible alternate strategy or <br />remedial sequence. It will allow all three potential sources of water quality impacts identified by <br />DRMS to be addressed simultaneously, will minimize overall health risks and environmental <br />impacts, and will facilitate realization of an effective, sustainable overall long -term solution in <br />the shortest time frame possible. <br />References <br />• The alluvial fill will be excavated and disposed <br />• Appropriate mitigation measures for the waste rock piles will be identified and <br />implemented <br />• Any core holes or seeps from the mine pool will be identified and sealed. <br />Ames, L. L., McGarrah, J. E., Walker, B. A. & Salter, P. F. 1983. Uranium and radium sorption <br />on amorphous ferric oxyhydroxide. Chemical Geology 40, 135 -148. <br />Banks, D., Royset, 0., Strand, T. & Skarphagen, H. 1995. Radioelement (U, Th, Rn) <br />concentrations in Norwegian bedrock groundwaters. Environmental Geology (Historical <br />Archive) 25(3), 165. <br />Bolivar, S.L., Broxton, D.E., and Olsen, C.E., 1978, Uranium hydrogeochemical and stream <br />sediment reconnaissance of the Denver and Greeley NTMS quadrangles, Colorado: Los Alamos <br />Scientific Laboratory informal report LA- 7177 -MS, Los Alamos, N.M., U.S. Department of <br />Energy, Grand Junction, Colo., GJBX- 60(78), 138 p. <br />Caine, J.S.; Johnson, R.H.; Wild, E.C. 2011. Review and interpretation of previous work and <br />new data on the hydrogeology of the Schwartzwalder Uranium Mine and vicinity, Jefferson <br />County, Colorado: U.S. Geological Survey Open -File Report 2011 -1092, 55 p. <br />Clear Creek Watershed Foundation (CCWF). 2011. Clear Creek Watershed Foundation <br />website: http: / /www.clearcrcekwater .ore /organization.html <br />12 <br />