Huge gaps remain in the largest Mount Milligan Mine buildings but not for long. They are quickly being filled in by sheet metal cladding, climbing the massive steel ribs around the primary ore crusher, the various grinding mills and the other parts of the production network for the gold-copper operation northwest of Prince George.
Getting these walls to lockup stage is more than a symbolic milestone. It means a better shot at obtaining even more construction workers.
It isn't easy, by typical building standards. The layout and exotic machinery of the processing plant looks like the villain's lair at the end of a classic James Bond movie. It is so tall and hollow inside you could easily bungee-jump from the rafters. The walls have the height of a small skyscraper but without the different floors to stage the work from, and the building is so cavernous it could hold an estimated six Costco warehouses.
"We are putting a lot of effort into getting the steel cladding on, because when that happens, all the construction and assembly work switches to indoors," said mill manager Pat Gannon. "As all kinds of construction projects slow down or stop for the winter, we will be ready to take those idle workers in from those projects and put them to work here."
There are already more than 1,100 workers on the mine's site each day, lately. More than 4.5 million person-hours of work have already gone into the construction of the project during the first 18 months of the building phase. They are on schedule to start processing gold and copper in the third quarter of next year.
"Most of our major contracts are starting to wind down," said Jocelyn Fraser, manager of corporate responsibility for ownership company Thompson Creek Metals. "In the coming months, as we complete the steps in the construction phase, those numbers will drop off and our permanent operational workforce (about 400 people) will begin their work."
"We are about 70 per cent complete," said Bert Jeffries, construction manager for the Mount Milligan site. The last 30 per cent includes finishing the truck maintenance shop, the massive processing plant, the 400-metre conveyer line, and a lake. Rather than discharging the massive amounts of liquid waste from the gold mining process (tailings) into an existing pond, Mount Milligan is building an earthen dam around the low-end of the mine to hold all that watery material. The fish-bearing lakes around the gold deposit, such as the nearby Alpine Lake, will not be affected. A few lakes without fish have been plugged into the fail-safe drainage field within the dam walls to collect any seepage, if any, of the tailings water.
"It's a bit unusual but this mine has no waste-rock storage. We are using all of the rock, and the materials we are taking off the surface to get down to the ore, as building material for the dam," said Jeffries. "What we have here is a landscape covered in impenetrable clay, and that is lining the dam walls. We are a zero-discharge operation."
The dam walls are founded at an elevation level of about 1,030 metres and will climb, dumptruck load by dumptruck load to a level of about 1,115 metres. It must be built up to 1,055 metres before tailings water can begin flowing into the manmade lake. "To get it ready for startup we have to move 5 million cubic metres of earth," said Jeffries.
To do that, a fleet of giant trucks is hauling the clay and rock from the two pit locations. Each of these mechanical beasts (Cat 793s, each so big they had to arrive in pieces and be assembled at the mine) can haul a 240-tonne load. An on-board scale gives a digital readout on the side of each truck so the shovel operator knows when it's full and the dirt accountants can keep an accurate file on two simultaneous jobs - cleaning the surface material off the gold, and shipping dam material to the levy walls.
Their dumpboxes are being filled by two shovels (Cat 7495s) that began full operation on Thursday. Each shovel is five stories tall and each one can fill one of the monolithic dumptrucks in two-and-a-half scoops.
Each of these shovels is so big, an adult can stand on the bottom of the caterpillar track and barely touch the top track; an entire hockey team could assemble in the shovel's scoop; and instead of a seat with a steering wheel the operator has a cockpit with a giant picture window, joysticks for each hand, a set of observation screens and a kitchen for break times. A long cable snakes like an orange python from the back of the machine, over the terrain, up some scaffold towers, and off to the power plant. Epic as they are, these machines run on electricity.
To set up a mine means setting up a small town at the same time. One of the major sideshows to the main act of gold mining was bringing in power lines over about 90 kilometres of wilderness from Mackenzie. That required modifications to that sending substation, and setting up a receiving building at Mount Milligan. Then, more than 20 kilometres of hydro line, plus fibreoptic cable, had to be strung strategically across the mine site to power the buildings and activities all over the sprawling facility.
Another alternative activity was the reclamation plan that is already underway in anticipation of the mine's end of life about 20 years from now. Fish stocks are being grown to populate the lakes without fish in the area, plus a native plant nursery is being developed, and the topsoil stockpiled for one day spreading back down.
"We have all these ancillary things to do, on top of the mine itself," said Jeffries. "We had to build a 110-foot wall for a ramp so the trucks could drive up and pour their loads onto the conveyer. We had to build a fuel farm - we have a lot of vehicles to fuel up."
"Fire, water, ambulance, food, sewer, all those capabilities of a city we have to have here," said Gannon.
"I'm like the mayor of one of the villages in northern B.C.," said Jeffries.
Like any major municipality, this town of Mount Milligan will have a gross domestic product, one day soon. By next fall the wheels of the conveyer belt will be reeling, the crushing mills will be pulverizing the big rocks into fine gold and copper ore, and the flotation vats will be percolating the precious elements into pure layers. Thompson Creek Metals estimates the Mount Milligan site will dig up about 100,000 tonnes of ore per day, process 60,000 of it per day (creating a large stockpile for down times in the digging), and draw out about 200,000 ounces of gold per year.
All from a space four kilometres wide by three kilometres long on a knobby mountain halfway between Fort St. James and Mackenzie.
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