Since 1982, Klohn Crippen has provided engineering services for the design and construction of the tailings dam at the Bullmoose Mine which is located about 30 km northwest of Tumbler Ridge in northeastern British Columbia. The mine operated from 1983 to 2003, and produced annually about 1.7 million tonnes of clean metallurgical coal and 600,000 tonnes of clean thermal coal.
The tailings facility consists of a side hill impoundment to store fine coal tailings. The tailings embankment is constructed of coarse coal refuse on a foundation of principally alluvial sand and gravel and is designed to be semi-impervious. Permeability zonation in the embankment is achieved by varying compaction effort of the material with the upstream sloping core more densely packed than the remaining embankment shell. The design calls for a 2.5H:1V downstream slope to a final height of about 40 m. Sufficient storage is maintained in the facility for flood storage with freeboard.
To date, seepage has been large enough such that discharge from the facility has not been required. The seepage passes through the base of the embankment into the alluvial foundation soil and then seeps into the downstream environment. No downstream seepage collection is performed or is required. In 2002, Klohn Crippen prepared the water management plan and a spillway design for the closure of the tailings facility in 2003.
- Site Investigation
- Performance Review
- Design of Tailings Dam
- Water Management Plan