Design construction of an evaporation pond at a historic uranium mining facility

摘要

In September, 2007, Denison Mines (USA) Corp. received permits from the Utah Division of Oil, Gas, and Mining to begin mining operations at the Tony M Mine, an underground uranium mine that was originally developed by Plateau Resources in the 1980's. Previous reclamation included breaching the dam that had been constructed to retain water pumped from the mine. Following geotechnical investigation by Tetra Tech during 2006, the dam and appurtenant facilities were re-designed, and construction occurred during 2007. The pond subgrade provided a cost effective, low permeability native barrier between the mine water and the underlying sediments. The liner consisted of reconditioned and densely compacted native clay overlying Brushy Basin Clay. Seepage through the pond liner and at the toe of the embankment was analyzed for steady-state and transient seepage conditions using a finite element computer model.rnConstruction of the evaporation pond involved some interesting challenges, including processing and compacting the clay soils, which had liquid limits in excess of 100. Laboratory permeability test results did not initially correlate well with field infiltration test results, however when alternative processing and testing methods were adopted the regulatory specifications were achieved. The native liner design and construction permitted a high quality, low permeability barrier to be constructed at a reasonable cost compared to the improbable and infeasible cost of a synthetic liner system in this remote area. Work is currently underway to investigate if similar techniques can be used to develop a larger evaporation facility for phase 2 of the mining operation at Tony M.