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• II! I H111111I IIl1 III • <br /> 999 <br /> FINANCIAL WARRANTY REQUIREMENT RE-EVALUATION <br /> SAN LUIS PROJECT M-88-112 <br /> March 10, 2000 <br /> TASKS AND COST ESTIMATES FOR REMAINING RECLAMATION OBLIGATIONS; <br /> WEST PIT WATER MANAGEMENT PROGRAM <br /> ASSUMPTIONS <br /> In order to clean up the West pit backfill, the operator needs to withdraw, and process, 4.91 pore <br /> volumes of water from the lower pit area and 5.24 pore volumes of water from the pink gneiss <br /> area(see attached "flush cycle calculations"). <br /> 1 pore volume equals 106,831,591 gallons in the lower pit and 11,408,470 gallons in the pink <br /> gneiss. <br /> 4.91 pore volumes in the lower pit equal 524,543,112 gallons. 5.24 pore volumes in the pink <br /> gneiss equal 59,780,383 gallons. Total for both areas equal 584,323,495 gallons. <br /> 2 processes and 1 alternative have been evaluated since they are the only approved operations. <br /> A) Nano-filtration process - Cost equals$6.90/1000 gallons treated (per ERI Technical <br /> Operations' January 29, 2000 bid for the water treatment system). 12 month operation. <br /> B) Evaporation system - $10,810.00/month (estimated labor and electricity costs for the <br /> backup system). <br /> The West pit water level will be pumped down to a msl of 8580 feet (for the lower pit. The pink <br /> gneiss water level should equalize at approximately 8604 feet msl) at 400 - 700 gpm. Thereafter, <br /> the aquifer will be pumped at the steady-state rate which is estimated at 110 gpm plus 70 gpm <br /> which BMRI anticipates pumping from the alluvial aquifer and re-injecting into the lower pit <br /> area. So, the total pump rate from the West pit is anticipated to be 180 gpm. <br /> It will take approximately 7.0 years to pump and treat the above-noted pore volumes of water. <br /> WATER MANAGEMENT TREATMENT AND ESTIMATED COSTS <br /> 584,323,495 gallons x $6.90/1000 gallons= $4,031,832 <br /> Monitor 8 wells at 1 sample/month at $100.00/sample = $9,600/year <br /> $9,600/year times 7.0 years =$67,200 <br /> CDPS discharge monitoring - 12 months times 4 samples/month times $200.00/sL:mple = <br /> $9,600/year <br /> $9,600/year times 7.0 years =$67,200 <br />