2000-03-10_REVISION - M1988112 - Laserfiche WebLink

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FINANCIAL WARRANTY REQUIREMENT RE-EVALUATION SAN LUIS PROJECT M-88-112 Mazch 10, 2000 TASKS AND COST ESTIMATES FOR REMAINING RECLAMATION OBLIGATIONS• WEST PIT WATER MANAGEMENT PROGRAM ASSUMPTIONS In order to clean up the Wes[ pit backfill, the operator needs to withdraw, and process, 4.91 pore volumes of water from [he lower pit area and 5.24 pore volumes of water from the pink gneiss area (see attached "flush cycle calculations"). 1 pore volume equals 106,831,591 gallons in the lower pit and 11,408,470 gallon., in the pink gneiss. 4.91 pore volumes in the lower pit equal 524,543,112 gallons. 5.24 pore volumes in the pink gneiss equal 59.780,383 gallons. Total for both areas equal 584,323,495 gallons. 2 processes and 1 alternative have been evaluated since they are the only approved operations. A) Nano-filtration process -Cost equals $6.90/1000 gallons treated (per ERI Technical Operations' January 29, 2000 bid for the water treatment system). 12 month operation. B) Evaporation system - $10,810.00/month (estimated labor and electricity costs for the backup system). The West pit water level will be pumped down to a msl of 8580 feet (for the lower pit. The pink gneiss water level should equalize at approximately 8604 feet msl) at 400 - 700 glom. Thereafter, the aquifer will be pumped a[ the steady-state rate which is estimated at 1 10 gpm plus 70 gpm which BMRI anticipates pumping from the alluvial aquifer and re-injecting into the lower pit area. So, the total pump rate from the West pit is anticipated to be 180 gpm. It will take approximately 7.0 years to pump and treat the above-noted pore volumes of water. WATER MANAGEMENT TREATMENT AND ESTIMATED COSTS 584,323,495 gallons x $6.90/1000 gallons = $4,031,832 Monitor 8 wells at ]sample/month at $100.00/sample = $9,600/year $9,600/yeaz times 7.0 years = $67,200 CDPS discharge monitoring - 12 months times 4 samples/month times $200.00/sample = $9,600/year $9,600/year times 7.0 years = $67,200