Truck Loading Waste-rock loading is carried out using two 1900 AL P&H 11-cu.-yd electric shovels, power being supplied from one of two 3000-KVA sub-stations, located in the pit, depending on shovel location. Power transmission from the main diesel power plant, located 6 miles (9.6 km) away, is by 24-kv pole line. Power to the shovel is carried by No. 2 A.W.G.S.H.G. 5-kv trailing cable at 4160 volts. The cable is lifted off the ground at all pot head connectors to ensure that it is visible during winter snow as well as to keep the pot heads dry during the spring snow melting period. Shovel maintenance, which is scheduled at 8-12 hours per week during daylight hours, coupled with pre- planning major overhauls, has ensured good mechan- ical availability for a northern location; it is currently running at 81% since the inception of the shovels. Major spare items have been purchased recently to ensure that components can be sent for overhaul with- out reducing the mechanical availability of the ma- chine. Hoist cables with socketed ends, and also a bail pin unit without sheaves, have been installed to reduce the time required to change broken hoist ropes. Shovels and other major equipment units are equipped with radios to ensure contact with the mine shift foreman or the mine garage in the event that re pairs are required. The high standard of radio main- tenance has assisted in ensuring excellent control of operations and minimizing downtime on equipment. A Caterpillar 824 rubber-tired tractor is used for cleaning up rock spillage around the shovels, moving cables during blasting operations and generally assist- ing in material movement. To maintain an acceptable grade elevation, Caterpillar D9G tractors are equipped with single-shank rippers. The digging limits with reference to the toe or crest positions are marked by stakes in the field and a daily reference survey is carried out by the surveyors to ensure that strict adherence to the line and level is maintained. To supplement the waste rock production units, a Caterpillar 992 10-cu.-yd front-end loader is used dur- ing the periods when the shovels are not available. Special emphasis is also placed on keeping the catch- ments clean, using the 992 front-end loaders (Fig. 5), to ensure that equipment or personnel working below the waste-rock excavation levels can work with safety. The 992 front-end loader was selected on the basis that it can load 50-ton, 75-ton and 85-ton trucks with ease, thus complementing the shovels. When using the Caterpillar 992 front-end loader, a dramatic increase in production has been achieved when a D8 or D9 tractor is deployed in pushing rock to the loader. The additional cost of using the tractor is more than compensated for by the increased produc- tion. A tractor is always used with the loader during catchment cleaning operations. Shovel production is running at 400 cu. yds per hour. However, when mining the less-competent serpentine rock associated with the orebody, production of 540 cu. yds per hour is not uncommon. All support equipment is Caterpillar supplied and maintained on a contract basis by Finning Tractor and Equipment Co. Ltd., Vancouver. A spare parts depot is located at the plant complex and a repair facility has been built in the pit. Haulage The haulage fleet employed on waste rock consists of eight R85 Euclids of 85-ton capacity, powered by Detroit Diesel 16V 92T 820-hp series engines with FIGURE 5— Caterpillar 922 front-end loader cleaning catch- FIGURE 4—A.N. prill storage silos—total capacity 210 tons. ments to avoid rock spills onto the ore faces below. DP8961 Allison transmissions, as well as six Wabco 75-ton-capacity trucks powered by VTA 1710-12V 700-hp Cummins engines with Allison DP8961 trans- missions. The 14 trucks are assigned to hanging-wall waste production. Normally, nine trucks are required to service the two 1900 AL P&H shovels and the Cater- pillar 992 front-end loader. Trucks are double-side loaded by the shovels whenever possible. Studies car- ried out indicated that a 40% increase in production can be obtained as compared to single-side loading. The shovel or drill trailing cables are protected at truck crossing points by inserting the cable in an Irathene elastomeric crossover pad containing a slot for the cable. A strip insert is placed in the slot to protect the cable, and the pad is covered by fine rock to protect the pad from damage during cold weather (Fig. 6). Haul ramps are designed 70 ft (21 m) wide at an 8-10% grade and are graded by a Caterpillar 16G grader, using serrated ice blades in winter. Grading on the dumps is maintained by D8 tractors with the assistance of the grader. A dump person is employed when trucks are dumping over the edge. All dump areas are lighted at night by portable light units; the SOT