The Storm copper project on Somerset Island in Nunavut has its first mineral reserve. Aston Bay Holdings, which holds a 20 percent free-carried interest, and operator American West Metals, which holds 80 percent, published a prefeasibility study on November 10 prepared by Sacre-Davey Engineering. The probable reserve is 12.58 million tonnes grading 1.20 percent copper and 3.7 grams per tonne silver, containing about 151,400 tonnes, or 334 million pounds, of copper and 1.50 million ounces of silver, effective November 1, 2026.
Total capital is C$164.69 million including C$23.66 million of contingency, split into C$37.90 million of pre-development capital, C$112.58 million of initial capital and C$14.21 million of expansion capital, plus a C$9.70 million closure allowance. The headline after-tax net present value of C$165.1 million at a 7 percent discount rate and internal rate of return of 32.8 percent are calculated at an assumed investment decision date of September 30, 2029 and exclude that pre-development capital; including all capital the figures are C$117.1 million and 21.5 percent. At spot prices of US$6.53 a pound for copper on November 2, the after-tax NPV rises to C$323.8 million with a 55.1 percent IRR. The base case uses US$5.30 a pound copper and US$50 an ounce silver.
The plan is a contractor-operated open pit across the Cyclone, Chinook, Corona and Thunder deposits, mining 83.28 million tonnes in total for a strip ratio of 5.6 to 1, with mining over about 8.6 years from January 2030 and processing to April 2040. Output is 688,290 dry tonnes of concentrate containing 103,035 tonnes of copper, at a C1 cash cost of US$3.45 a pound and all-in sustaining cost of US$3.73 a pound of payable copper after silver credits. Ocean Partners holds a binding offtake over all base production and has agreed to provide debt of up to 80 percent of initial capital, subject to a bankable feasibility study and formal documentation, which the release states is not committed funding.
The study is a prefeasibility study, not a feasibility study, its cost estimates carry an accuracy range of minus 30 percent to plus 50 percent, and the companies state plainly that no decision to develop the project has been made.