Phase Ii Title I Engineering Assessment Of Inactive Uranium Mill Tailings Monument Valley Site Monument Valley Arizona Environmental Effects Health Hazards And Options For Stabilization Of Tailings Or Fencing Of Site

An engineering assessment was made of the problems resulting from the existence of radioactive uranium mill tailings at the Monument Valley millsite in Arizona. 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 residing nearby, the investigation of site hydrology and meteorology and the evaluation and costing of alternative corrective actions. Radon gas release from the tailings on the site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation are also factors. The sparse population and relatively low radiation levels yield minimal immediate environmental impact; hence, the two alternative actions presented are directed towards restricting access to the site and returning the windblown tailings to the pile and stabilizing the pile. Both options include remedial action costs for offsite locations where tailings have been placed. Cost estimates for the two options are $585,000 and $1,165,000.