Lorado Uranium Mill Remediation
Located approximately 8 kilometres southwest of Uranium City, Saskatchewan
Tailings Cover and Peripheral Area Remediation
Client: Saskatchewan Research Council
Project Scope Performed Under: PBN Nuna/Milestone Joint Venture (PBNM JV), a partnership of PBN Nuna Contracting Joint Venture (managing partner) and Milestone Environmental Contractors Inc.
The Saskatchewan Research Council (SRC) manages Project CLEANS, a multi-year, multimillion-dollar project to assess and reclaim abandoned uranium mines and mill sites comprising the Lorado Uranium Mill site, the Gunnar Uranium Mine & Mill site, and 35 satellite mine sites in northern Saskatchewan. The projects are funded by the governments of Saskatchewan and Canada.
The Lorado Uranium Mill site, being one of the more complex reclamations, is located approximately 8 kilometres southwest of Uranium City, SK. The mill was constructed in 1957 and operated until 1960. Between 305,000 and 545,000 tonnes of low-grade uranium ore was processed through the mill, and approximately 227,000 cubic metres of tailings material was produced during the mine’s operational lifetime. The Lorado contract was performed under the PBN Nuna/Milestone Joint Venture (PBNM JV), a partnership of PBN Nuna Contracting Joint Venture (managing partner) and Milestone Environmental Contractors Inc.
PBNM JV’s scope included the construction of all civil works. Milestone Environmental’s scope included water treatment on the highly acidic Nero Lake. PBNM JV’s specific role was to remediate the roughly 18-hectare tailings area by covering the tailings with sand and till per strict design parameters. Prior to the placement of the cover layer, two permanent drainage channels were built to remove surface water from the area, and the tailings footprint was fully graded to exacting tolerances to maintain a positive surface flow towards Nero Lake and prohibit ponding.
The design required the placement of a 1.0-metre-thick sand layer and 0.25-metre till layer on the upland tailings cover, representing the entire land area above the water. The beach sand cover placement scope required only sand placement into Nero Lake to a depth of 1.8 metres. PBNM JV’s scope also entailed the remediation of 10 contaminated satellite sites in the vicinity, which called for debris management and land cover by till.
The treatment of Nero Lake to bring it up to a near neutral pH condition was completed in the 2014 summer season with the addition of 400 tonnes of lime by Milestone Environmental. PBN Nuna set up the water treatment facility and piping to add the lime and circulate the water. At the end of September 2015, the tailings cover was completed and included load, haul, and placement of 193,000 cubic metres of upland sand, 61,000 cubic metres of beach sand, and 93,000 cubic metres of upland till.
In addition to the volume of material placed on the tailings cover system, 20,000 cubic metres of till were placed on the peripheral areas. For protection, and to prevent sand from washing away, a geotextile layer was laid along the shoreline and covered with a layer of rip rap to prevent erosion. PBNM JV also developed 6 borrow pits to ensure adequate supply of material to meet narrow specifications relating to future percolation of water, restored borrow sites, and constructed and maintained site roads.
The contract contained success criteria that included measurement of contractor engagement with Athabasca Basin personnel and businesses. The 3 primary KPIs included the following.
- Local hiring
- Local equipment utilization
- Local spend
PBNM JV successfully surpassed these targets and completed the project on time (October 2015).
In July 2016, the SRC was presented with the Project Management Institute (North Saskatchewan Chapter) 2016 Project of the Year Award. PBN Nuna/Milestone Joint Venture were acknowledged by SRC for their significant contributions (earthworks and consultation) to the project’s success and award achievement.