This report is a summary of a parent report DOE/UMT--0108. These reports have become necessary as a result of changes that have occurred since 1977 which pertain to the Rifle sites and vicinity, as well as changes in remedial action criteria. The new data reflecting these changes are summarized in this report.

Ford, Bacon and Davis Utah Inc. has performed an engineering assessment of the problems resulting from the existence of radioactive uranium mill tailings at Rifle, Colorado. The Phase II--Title I services include the preparation of topographic maps, the performance of core drillings and radiometric measurements sufficient to determine areas and volumes of tailings and other radium-contaminated materials, the evaluation of resulting radiation exposures of individuals and nearby populations, the investigation of site hydrology and meteorology and the evaluation and costing of alternative corrective actions. Radon gas release from the 3.1 million tons of tailings at the two Rifle sites, constitutes the most significant environmental impact. Windblown tailings, external gamma radiation and localized contamination of surface waters are other environmental effects. The 15 alternative remedial action options presented range from millsite decontamination and off-site remedial action (Options I and IV), to adding various depths of stabilization cover material (Options II, V, VI and VII), to removal of the tailings to long-term storage sites and decontamination of the present sites (Options III and VIII through XV). Cost estimates for the first 14 options range from $224,000 to $20,300,000. Option XV, estimated at $32,200,000, includes the cost for moving both Rifle tailings piles and the Grand Junction tailings pile to DeBeque for long-term storage and site decontamination after removal of the piles. Reprocessing of the tailings for uranium appears to be economically attractive at present.