1995-08-11_REVISION - M1977493 (10)

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01/11/1995 08:36 2168648136 MVTECHNOLOGIES, INC. PAGE 05 2 P1 LX= CATION Statement of Problem The major problem at the McNulty rock dump is the acidification of surface water and groundwater by contact with acid-generating waste rock. The acid mine drainage (AMD) emerges at the toe of the waste rock dump and is collected in a holding pn*ic1. Site Description The McNulty waste rock dump is a part of the Climax Molybdenum Company mine located in Climax, Colorado. The dump covers approximately 450 acres. Overburden rock from the operation of the surface pit is transported by truck to the dump and is end dumped. Bulldozers then place and compact the rock. The dump has been constructed in a series of benches with relatively steep outslopes ranging from 1.5:1 to 2:1. There are approximately five distinct rock types in the dump. The molybdenite occurs disseminated in quartz veins transversing granite. Upon oxidation, the material acquires an orange-red cast indicating that ferric oxides predominate. The rock deposited at the dump ranges in size from large boulders to fines. As a result the majority of the large rock is found at the base of each lift and this creates large void areas within the dump for the passage of infiltrating ground and surface water. There are no surface water diversion channels to keep the water from contacting the waste rock. All precipitation and snowmelt from the upgradient watershed passes over and through the- rock dump. There are some perched water tables that discharge groundwater into the dump. All of the infiltrating ground and surface water eventually emerges as AMD at the toe of the waste rock dump. This AMID is collected in a holding pond where it is allowed to evaporate. If the pond should overflow, the water can either be diverted to the water processing system or to the Robinson tailings pond. The McNulty rock dump is still available for further rock disposal when the Climax Mine is reactivated. Presently, the mine is inactive due to economic conditions. Site Visit and Sampling Water samples (Table 1) , waste rock samples (Table 2), and photographic records of the site were obtained. A visual inspection of the site was conducted. Semple Preparation and Laboratory Analyses. All waste rock samples were air- dried, mixed., pulverized and riffle split into representative subsomples for chemical analysis.