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File No. M-77-378 <br /> Page Two <br /> 3) The leakage around the bulkheads is expected to be 1 gallon <br /> per minute or less (total for all four bulkheads) . Under <br /> worst case conditions (ie maximum conceivable head, maximum <br /> permeability and maximum fracture pattern) , total leakage <br /> would be 70 gallons per minute. This is a very unlikely <br /> scenario. <br /> 4) The impounded water is expected to be mostly nonreactive (ie <br /> saturated with respect to exposed minerals within the mine) . <br /> If precipitation occurs as equilibrium conditions predict, the <br /> quality of the impounded water will be of better quality than <br /> the existing discharges from the Sunnyside Mine before <br /> treatment (Table A-11. March 12 , 1993 study) . <br /> 5) The flow through the Sunnyside Mine is expected to be less <br /> than the existing average combined flow (American Tunnel and <br /> Terry Tunnel) of 1150 GPM from the Sunnyside Mine property. <br /> This flow under most likely conditions is modeled to be a <br /> total of 74 GPM. It is estimated that it will take 160 years <br /> for 70 GPM of this total to reach surface but 4 GPM will <br /> discharge via the Mogul Mine in approximately 16 years. Under <br /> worst case conditions, which is considered unlikely, the total <br /> flow through the Sunnyside Mine will be 360 GPM (still much <br /> less than existing conditions) . Under these conditions it <br /> will still take approximately 10 years for 200 GPM to reach <br /> surface but only 4 months for the remaining 160 GPM to exit <br /> via the Mogul Mine. <br /> 6) Cement Creek water quality above the minesite will not <br /> significantly change after bulkhead placement in comparison to <br /> water quality that presently exists. A table for comparison <br /> of metals loading that would be allowed by the American Tunnel <br /> CDPS permit and metals loading from the anticipated 74 GPM <br /> flow after bulkhead placement is presented below. The table <br /> uses 30 day average allowable numerical limits in the CDPS <br /> permit converted to lb. per day loading at a 1150 GPM flow <br /> rate. <br /> Metal Loading (lb/day) <br /> CDPS (30 day avg. limit) Projected Metal Loading 4 : 1 mix <br /> Metal 16 years 160 years <br /> 1150 GPM 4 GPM 74 GPM <br /> Fe No limit - 0 <br /> Mn No limit - 0 <br /> Zn 10. 4 1 .4 8 . 0 <br /> Cd 0. 7 0. 0005 0. 01 <br /> Pb 4. 1 0. 01 0. 2 <br /> Cu 2 . 1 0. 01 0. 2 <br />