The Mount Milligan Project is a copper-gold deposit located in Northern BC. Ledcor and Duz Cho Construction LP (owned and operated by the MacLeod Lake Indian Band) teamed up to provide earthworks construction services for the $85M project.
Initially, 26 kilometres of forest service road was upgraded to provide access to the future mine site. Work included subgrade construction with a scraper fleet, placement of a gravel road cap, and installation of three bridges and three large diameter culverts. Subsequently, the construction camp pad and mine road infrastructure was built for a 700-man construction camp.
The initial tailings storage facility was constructed, along with the rough earthworks for the plant site and truck shop. Over 2,000,000 m3 of earthworks was required for these facilities and this work was carried out in the winter of 2010/11. A 20 metre deep cut-off trench was excavated in the King Richard Creek Valley to provide a seepage barrier for the future tailings dam, and a dozen deep dewatering wells were installed to control the seepage inflow during construction. An initial 15 metre high embankment was built alongside the cut-off trench and this embankment was raised by 10 metres in the summer of 2011. Critical areas of the tailings basin were covered in a low permeable blanket to prevent potential seepage.
Ledcor-Duz Cho had up to 200 personnel on site to work a continuous, 24-hour shift to complete the work prior to the 2011 spring run-off.