Case 11-2 SA Gold Mine: Earned Value After a Scope Change29 The team at SA gold mine was tasked to sink a 2,000 meter deep ventilation shaft, and then to excavate room for a station at the bottom of the shaft. The approved plan was to sink the shaft within 20 months at a cost of R65,000 (approxi mately US $10,000) per meter of shaft depth. For the station at the bottom, 30,000 cubic meter of rock would have to be excavated within 3 months