Slime dewatering at the Homestake's Grants Project

Dewatering the uranium tailings at Homestake’s Grants uranium mill site is very important to the long term impacts on the ground-water system and was initiated in 1995. Vertical dewatering wells are used to remove the drainable water in the slimes. Average pumping rates are slightly less than 1 gallon per minute (gpm)/well. Collection rates are being enhanced by the use of vacuum in wells, which have a sufficiently small air flow rate. The volume of drainable water is estimated using water levels in wells and neutron logs from the tailings wells. The specific yield of the tailings is very important with respect to the volume of drainable water and, therefore, the life of the dewatering program. A dewatering plan, operational through the year 2004, is anticipated to remove the drainable water in the tailings. Total production from the dewatering program and production from individual slime wells is expected to gradually decline with time. Approximately 90 dewatering wells are currently being used and an additional 60 wells will likely be required to complete the dewatering program.