1995-08-11_REVISION - M1977493 (9)

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. Water treated by the alkaline hydroxide process in the Mayflower tailing impoundment water pool is decanted from the pool at approximately pH:10.5-11.5. The Climax discharge permit stipulates that discharged water be within the range pH 6.5-9. Therefore, as discussed previously, pH is adjusted to pH 7.8 by dripping sulfuric acid into the water stream as it leaves the pipe. Interceptor Canal System: An extensive clear water interceptor system has been established by Climax around the affected areas of the upper Ten Mile Creek watershed. The primary interceptor canals (Figure 1) total 13 miles and are labeled as the west interceptor canal and the east interceptor canal. These canals were constructed in the 1970s during construction of the Mayflower tailing impoundment to intercept and convey snow-melt and stormwater around the three tailing impoundments in the Ten Mile Creek watershed. The west interceptor canal begins at the Robinson impoundment and drains directly into Ten Mile Creek within the Climax property line downstream of the Mayflower impoundment. The top portion of this canal has a capacity of 15 cfs while the the lower portion between Searle Gulch and Ten Mile Creek has a capacity of 75 cfs. The east interceptor canal begins at the edge of the McNulty dump and terminates at the Clinton Gulch Reservoir. Its capacity ranges from 30 cfs at the top to 78 cfs at the terminal point. The total interceptor system handles approximately 14,500 acre feet of water annually. Additional information regarding the interceptor system is found in Appendix E. The interceptor canals stem is considered an EPF because its function of conveying P Y Y g stormwaters around the process facility and tailing impoundments. This function serves to help preserve the stability and integrity of the impoundments and their features and to limit the amount of excess water which must be treated and discharged. The Climax interceptor system also collects and conveys non-point source run-off from historic mine sites located above the interceptors. A number of these sites are located on lands administered by the U.S. Forest Service. Dust Suppression: Fugitive dust from the beach area on the Ten Mile tailing impoundment and No. 3 Dam can be generated during periods of high winds following periods of no or very little precipitation in the summer and fall. Consequently, an interim method of suppressing wind- blown tailing dust has been employed at Climax. Upon final closure, capping and revegetation of these areas will eliminate dust releases. In the late 1980s, airborne fugitive dust was a continuing problem from all three tailing impoundments and their respective dams. In 1986, Climax was cited by the MLRB and the Colorado APCD for excessive blowing tailing dust. As a result of this situation and the high annual cost of applying a chemical dust suppressant (which was done since the mid-1970s), Climax initiated capping and reclamation of the beach areas and dam at the Mayflower tailing impoundment; a project which eliminated the release of fugitive tailing dust. This project was 28