Deep overburden shaft collar - Musselwhite project case history

"Placer Dome Inc. is the operator of the Musselwhite project located 100km north of Pickle Lake, Ontario. J.S. Redpath Limited was contracted to conduct an underground exploration program using shaft access.During the winter of1988, the shaft collar was established in 16 metres of water bearing sand and till overburden. This paper will illustrates the engineering techniques used to overcome the obstacles to installing a shaft collar in deep overburden. Specialized dewatering and piling procedures were employed.INTRODUCTIONHarold and Allan Musselwhite discovered gold in the Opapimiskan Lake area, north of Pickle Lake, in 1962. The prospectors were grubstaked by ten companies in 1973.A diamond drill program was initiated shortly thereafter.In 1983an underground ramp exploration program was carried out on the West Anticline portion of the property. The program was unsuccessful in establishing an ore reserve so surface exploration continued. In 1986the ""T"" zone was discovered. Further surface drilling was done and an over-all drill-indicated reserve of 6 million tonnes at 7 grams per tonne was outlined. The gold mineralization occurs in several vertical tabular deposits within the iron formation. In late 1987the joint venture partnership, now consisting of Placer Dome Inc., Inco Gold Co., Corona Corporation and Esso Minerals Canada, contracted J.S. Redpath Limited to conduct an underground exploration program on the ""T"" Zone.The scope of work for the project was to: 1. establish a 45 km winter road in 1988 and 1989;"