Composite Cutoff Wall Construction for the Diavik Diamond Mine in Northern Territories Canada

The Diavik mine is operated by Diavik Diamond Mines Inc., a member of the Rio Tinto Group, and is located approximately 220 kilometers south of the Arctic Circle and 300 kilometers by air from Yellowknife, the territorial capital. A deep cut-off wall was required for the 2.2 km perimeter dike so that the fourth kimberlite pipe, designated A21 and located under the waters of Lac de Gras, could be open-pit mined.
A combination of different foundation engineering techniques were utilized to execute the proposed cutoff wall including vibro-densification, curtain grouting, Cutter Soil Mixing (CSM) and jet grouting. The location of the mine presented special weather challenges, enabling works only between May and October. Logistics was another major challenge, as large transports are only possible during an eight week window during the winter when the ice road to the mine is open.
The paper will present the design of the cutoff wall through the use of the various techniques, the execution of the work under harsh conditions and the quality control and as built program used to verify the quality and integrity of the wall.