Klohn Crippen designed and performed construction management for the Shikano North pervious rockfill tailings dam at the Quintette coal mine in North-Eastern British Columbia. The dam was built to create the Shikano North In-Pit Tailings Impoundment. This facility provided storage for fine coal tailings produced by Quintette’s coal washing plant and had an operating life of 5 to 7 years. Tailings deposition commenced in February of 1997 and ceased in 2000 following mine closure.
The Shikano North Pit comprises a 1200 m long trench cut across the outcropping coal seams in the Shikano deposit. The depth of the trench is 25 m at the northwest end and increases to 200 m at the southeast end. The Shikano North Tailings Impoundment was formed by the tailings dam constructed across the outlet of the trench at the northwest end. Tailings were discharged over the face of the pitwall at the southeast end of the pit. The deposited tailings solids formed a flat beach sloping at 0.5% towards the tailings dam. The tailings slurry water which ran off the beach surface pooled in a shallow pond against the upstream face of the dam. Because of the continuous flow of water across the narrow tailings beach, problems of wind erosion and dusting on exposed tailings beach surfaces were minimized.
The tailings dam was designed as a pervious structure to continuously decant the tailings pond by seepage through the dam. This eliminated the need for a $2M reclaim water pumping system to transfer the tailings water from the impoundment. The tailings dam itself was a compacted rockfill embankment with a pervious upstream filter zone to control the rate of seepage and prevent the tailings from migrating through the rockfill. The filter zone consisted of processed coarse and fine filter material covered by a geotextile filter fabric on the upstream side.
- Site Investigation
- Construction Management