1996-02-06_REVISION - M1977493 (11)

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Mr. Allen Sorenson Division of Minerals and Geology February 1, 1996 Page 3 CMC feels that any discussion of aquatic biological data referenced in the 1977 Climax Reclamation Permit and the 1989 Amendment is outside the scope of the EPP. The data were referenced in the Climax Reclamation Permit for informational purposes, the results for which are not considered to be subject to discussions of permit conditions. At this time, without further justification, Climax Molybdenum Company will not submit either additional water quality information or a surface water monitoring plan. 5. Please correct the reference in Section 5.3.2 of the EPP stating that NaCN solution concentrations at Climax are 5 %. The actual mixed solution concentration of NaCN solution stored in the 3300 and 240 gallon tanks ranges from 5 to 10 %. While CMC holds actual concentrations of NaCN and other reagents in the milling circuit as Confidential Business Information, DMG should assume that concentrations all reagents range from 0 to storage concentration (2.4 M for NaCN) at any point of the milling process. Sodium hydroxide is stored in solid form and in solutions from 50% and 73% concentrations. The actual concentration of the P2S5 in solutions used at Climax ranges from 0 to 0.3 M dependent upon whether or not pre -mixed reagent is utilized or mixing takes place on site. Sulfuric acid is undiluted 12 M solution in storage. This information is'being submitted for informational purposes only. These numbers can change with changes in processing of molybdenite and are therefore are not binding as permit conditions. 6. The NaCN strength in the storage tank can range as high as ten percent. The addition rate of NaCN solution to the regrind circuit is approximately 0.2 to 0.6 gallons per minute. The process water flow out of the tail box and down the tail line is on the order of 10,000 to 15,000 gallons per minute under average conditions. Peak flow in the tailing line may approach as much as 50,000 gallons per minute. Of course the cyanide solution goes through several stages of processing before reaching the tail line resulting in consumption and chemical oxidation of this constituent. The solution strength is even lower than the one calculated by the ratio of the flows mentioned above. Please note a correction to the SPCC Plan Table 1. The concentration of cyanide used at Climax is not 0.49 lbs/ton as the units for this number are in gpm. The correct value is 0.02 Ibs /ton. In the event that the entire storage would be discharged to the tailing impoundment, the solution would be contained in the East Tailing Delivery Line for approximately 2.5 miles and discharged into the Tenmile Tailing Impoundment. The delivery of the 3540 gallons would be associated with 10,000 to 15,000 gallons per minute of tailing line flow. Assuming a minimum flow in the tailing line of 10,000 gallons and a spill event lasting a conservative 10 minutes, the resulting solution concentration discharged into the Tenmile Tailing Pond would be less than 2.7 g /I. The storage capacity of the Tenmile Tailing Pond is, at low storage, in excess of 650 acre feet. The resulting solution once discharged to Tenmile Tailing Pond would be 0.22 mg /I. This concentration is less than the maximum daily discharge limit of the Climax CPDS Permit. Please note that the containment is controlled by a valve.