Diavik Diamond Mine
Processed Kimberlite Containment & North Country Rock Pile Labour Support (2019-Present)
Completed: In Progress
Client: Diavik Diamond Mines Inc. (Rio Tinto PLC)
In early 2019 Nuna Logistics was awarded a 3-year contract to complete two distinct scopes of work. The first is a continuation of ongoing work to re-slope the mine waste rock pile for eventual mine closure. Once the pile is sloped, layers of till and rock will be placed to ensure the reclaimed structure isn’t affected by weathering and erosion and will create habitat for local wildlife.
The larger portion of the work is in the Processed Kimberlite Containment area where Nuna will construct a zoned rockfill dam raise in the existing facility. This includes the loading, haulage, and placement of coarse processed kimberlite in thin lifts, trimming of side slopes, installation of a liner, and extension of roads and pipe access points. All this work will take place in an active deposition area, requiring coordination of activities with numerous groups. Nuna crews will also be installing geotechnical instrumentation in both work areas to allow ongoing monitoring of structural integrity and settling.
A21 Dike Support (2015-2018)
Diavik Diamond Mines Inc. (DDMI) has leveraged Nuna’s experience on heavy civil projects, capability to budget and schedule, and ability to supply qualified personnel to make the A21 project grow in scope from a simple manpower provider to a vital part of the DDMI construction team.
Nuna’s 2016-2018 scope included:
- Supply of labour, large mine equipment operators, and equipment to support DDMI and Bauer construction of the A21 dike cut-off wall including raising dike elevation, pipe benches, and roads.
- Supply of embedded personnel: 2 site services operators; 8 Cat D10 dozer operators; 4 underground operators; and numerous management and administrative positions including Superintendent, Senior Advisor, Field Coordinators, and Travel Coordinator.
- Support and liaise between DDMI and the contractors of various cultures (multi-language) on the project performing functions including: cut-off wall foundation; marine and barge; engineers of record; electrical; site services; scaffolding and carpentry; survey; dike thermosiphons; mobile plant maintenance; and janitorial and logistics.
- Provision of backfilling services during vibrodensification to produce dike columns (vibro tool vibrates into the ground and consolidates the existing material; once the tool has reached the desired elevation, the hole is backfilled with 2” material and vibrated again so the result is a complete hard column).
- Operation of water buggies and grout plant for dike curtain grouting.
- Provision of labour, concrete mixer trucks, and excavators; and development of trenches and installation of concrete templates for pre-drill rigs (BG30 and BG40).
- Provision of crane services and excavator support to clear the spoils generated from dike cutter soil mixing wall construction.
Processed Kimberlite Containment (PKC) Dam
Initial Construction & Subsequent Raises (2007-2009)
Work comprised the initial construction of 5.5 linear km of containment and subsequent raising of the PKC dam (5 m to 15 m lifts) which entailed blasting and excavation of the key trench to bedrock and/or permafrost, leveling with till material, and placement of HDPE liner locked in with a till plug. Structure comprised rock fill, liner bedding, liner, and placement of rock fill for thermal protection.
A418 Dike Construction, Dewatering & Pre-Stripping (2005-2006)
Kimberlite pipe A418 required construction of a water retaining dike and cut-off wall. A418 dike is 1.2 km long, located in water up to 32 m deep, and required approximately 1.1 million m3 of rockfill.
A418 dike joins existing A154 dike, and construction methods similar to those used in A154 dike were utilized – various sizes of rockfill, a central plastic concrete cut-off wall, jet and curtain grouting, and installation of instrumentation. A significant crushing facility prepared much of the rock before placement using rock from the A154 open pit. The rockfill portion of the A418 dike was completed in 2005, and the cut-off wall completed in 2006.
A154 Dike Construction, Dewatering & Pre-Stripping (2001-2002)
Located 20 m below water off an island in Lac de Gras, the A154 kimberlite pipe required construction of a 3.8 km long, up to 25 m high dike to enclose an area 1.5 km2. Lac de Gras Constructors, a partnership between Nuna and Peter Kiewit Sons Ltd., was awarded the construction contract in 2000.
During the 2001 season, 5,000,000 m3 of rock was excavated and 6,000,000 tonnes of crushed granular aggregate 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.
Work included: installation of turbidity curtains; foundation preparation (dredging); placement of filter material on lake bed floor; placement of embankment (3 types of materials); vibrodensification of materials; excavation through central core to facilitate cut-off wall; trenching on land and in shallow waters for cut-off wall in some areas; placement of abutment insulations, which included thermosiphons, drainage, and toe berms; and relief wells and installation of geotechnical instrumentation. Jet grouting was required along the entire length of the dike between the cut-off/bedrock interface and curtain grouting below the cut-off in the bedrock. Civil infrastructure work included pads, tank farm containments, airstrip construction, installation of Hilfiker wall, and supply and placement of structural concrete.
North Inlet Dike (2001)
The 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.
Early Works (seasonal between 1998 & 2000)
- Preparation of the exploration site and placement of site facilities.
- Installation of a remote development site comprising camps, shops, fuel storage, and mining supplies sufficient for a 10-month underground bulk sample program. The program included drill/blast and muck of a decline adit.
- Annual winter road access construction and maintenance.
- Reverse circulation drill support for an extensive drilling program which included establishing drill pads on the Lac de Gras ice for the annual drill program.
- Preparation and transportation of a 3,000-tonne bulk sample from the A154 site to the pilot plant in Yellowknife.
- Constructability review for the Diavik feasibility study prepared by Nishi-Khon/SNC¨Lavalin Limited.