The mine is located approximately 220km south of the Arctic Circle and 300km by air from Yellowknife, the territorial capital.
A 26m-deep cut-off wall is required for the 2.2km dike so that an area located under the waters of Lac de Gras can be open-pit mined. Bauer offered the cutter-soil-mixing method (CSM), which combines cutter diaphragm walling technologies and the mixed-in-place method. The CSM technique is implemented through the use of trench cutters that are specially modified for this process. By using the in-situ soils, the CSM technique provides substantial logistic advantages and cost savings compared to more traditional methods, said Bauer.
The location of the mine presents special challenges: work can only be done between May and October because temperatures are too low during the winter months. Logistics is another major challenge, as large transports are only possible during an eight-week period in the winter when the ice road to the mine is open.
As a result, the project will be completed in two stages in 2016 and 2017. In 2016, the company will use two Bauer BG 30 rotary drilling rigs, three universal drilling rigs from Klemm Bohrtechnik and cranes to complete soil improvement, perform trials, carry out curtain grouting work in the underlying rock and some other essential preliminary works for the cut-off wall.
In 2017, the cut-off wall will be completed using the CSM method and jet grouting. Five BG 30 rigs will be used for this final stage of the project. These BG 30s will be specially configured to carry out three activities on this project: pre-drilling, CSM work and jet grouting.
The project marks a return to the subarctic site for the Bauer Group. From 2000 to 2002, Bauer Maschinen – in partnership with other companies and using a range of equipment – was involved in the construction of the water retention dikes that enabled open-pit mining of diamonds.
"It's a great story that our company is returning to Diavik almost 15 years later to take an active part in the further progression of the mine,” said Professor Thomas Bauer, chairman of the management board of Bauer AG. “It shows that the client has great confidence in our services.”