1999-12-22_REVISION - M1988112 - Laserfiche WebLink

Home Browse Search

FINANCIAL WARRANTY REQUIIZEMENT RE-EVALUATION SAN LUIS PROJECT M-88-1 l2 January 5, 2000 TASKS AND COST ESTIMATES FOR REMAINING RECLAMATION OBLIGATIONS WEST PIT WATER MANAGEMENT PROGRAM ASSUMPTIONS In order to clean up the West pit backfill, the operator needs to withdraw, and process, 10 pore volumes of water from the aquifer. 1 pore volume equals 180,700,000 gallons 10 pore volumes equal 1,807,000,000 gallons 2 processes and l alternative have been evaluated since they are the only approved operations. A) Nano-filtration process -Cost equals $9.43/1000 gallons treated. 7 month ~~peration. B) Evaporation system - $10,810.00/month for 5 months The West pit water level will be pumped down IS feet (to a msl of 8580feet) at 400 gpm for 70 days. Thereafter, the aquifer will be pumped at the steady state rate which is estimated at 180 gpm. Since the water level has already been lowered 3 feet (to 8592 ms]), it should only take 56 days, and 32,256,000 gallons, to lower the water level another 12 feet (at 400 gpm). 32,256,000 gallons of water will be pumped during the first 56 days. 259,200 gallons/day will be pumped thereafter. The operator has already removed 44,201,933 gallons of water from the backfill aquifer up to December 1, 1999 (this does not include the volume of water that has exited the West pit into the alluvial aquifer). It will take approximately 18.5 years to pump and treat 10 pore volumes of water. This is based on 1,807,000,000 minus what has already been pumped, minus 32,256,000 gallons which will be pumped during the first 56 days; divided by 259,200 gallons (daily pump rate). WATER MANAGEMENT TREATMENT AND ESTIMATED COSTS First year's treatment starting February 1, 2000 1) 56 days at 400 gpm equals 32,256,000 gallons at $9.43/1000 gallons = $30x,174 2) 126 days at 180 gpm equals 32,659,200 gallons at $9.43/1000 gallons = $307,976 3) 5 months evaporation system at $10,810.00/month = $54,050 4) Total = $666,200