All components of Gunnison are now ready to be energised, including the transmission line to the production wellfield, after being linked over the local Interstate 10 freeway to the newly relocated and upgraded substation located at Johnson Camp mine.

"At the new substation, power will be transformed for distribution throughout the processing plant," Excelsior said of the 69,000-volt line. "[We have] also completed new power transmission lines with pole transformers for the hydraulic control wells and to the evaporation pond."

President and CEO Stephen Twyerould confirmed the project was completed on time and on budget per its schedule.

Gunnison, which the miner wholly owns, is south-east of Tucson and is situated on 9,560 acres (3.9 hectares) within the North Star deposit of the copper porphyry belt. It has a 24-year mine life. Excelsior is planning an environmentally friendly extraction programme, with low water consumption, no groundwater contamination and no acid mine drainage, as well as an "excellent" plan for the mine's closure.