Dikes serve to isolate portions of lake beds from the main lake body providing accessibility for open pit mining. NUNA continues to provide efficient and cost-effective dam and dike construction services to the majority of resource companies operating in Nunavut and the Northwest Territories.
A154 Dike, A418 Dike, North Inlet Dike
Diavik Diamond Mines Inc., Diavik Diamond Mine, Northwest Territories, Canada
A154 is the 1st dike of its kind constructed in Canada - Located 20 m below water off an island in Lac de Gras lake, the A154 kimberlite pipe required construction of a 3.8 km long, up to 25 m high dike to enclose an area of 1.5 km2. During 2001 season 5,000,000 m3 of rock was excavated and 6,000,000 tonnes of crushed granular aggregates was produced and placed to complete the dike. Excavation along the central core of the dike allowed the installation of a bentonite cut-off wall of 51,000 m2.
A418 Kimberlite Pipe Dike Construction, De-watering & Prestripping - A418 dike is 1.2 km long, required approximately 1.1 m3 of rockfill and is built in water up to 32 m deep. A418 dike joins the existing A154 dike with construction methods being similar as those used in A154 dike - various sizes of rockfill, a central plastic concrete cut-off-wall, jet and curtain grouting and installation of instrumentation. Using rock from A154 open pit, a significant crushing facility prepared much of the rock before placement. The rockfill portion of the A418 dike was completed in 2005, and the cutoff wall completed in 2006.
North Inlet Dike was constructed prior to the A154 dike and provided a test platform to confirm the cut-off wall constructability criteria. This project consisted of backfilling the core with granular material, vibrodensification and jet grouting columns.