Uranium City Permanent Mine Covers

Kova was selected to provide engineering and quality control services for design, fabrication, and installation of permanent mine opening covers for the Beaverlodge area near Uranium City, Saskatchewan. The Beaverlodge area includes a large decommissioned uranium mining and milling site as well as a number of satellite mining sites. Each of these sites contains several mine related openings created to provide access to the underground workings via production shafts or ventilation raises.

The Beaverlodge mine operated as a federal government crown corporation from 1952 to 1982. Once the mine was shut down in 1982, decommissioning was conducted over a period from 1983 to 1985. Part of the original decommissioning activities involved sealing historic mine openings by capping them with concrete. While an outline of the remediation plans were provided in the decommissioning reports, no records of “as-built drawings” detailing exactly how each opening was decommissioned are available. As the province of Saskatchewan will require engineer stamped documentation regarding the final closure method, a decision was made to replace or cover all existing concrete caps with stainless steel covers to maximize useful lifespan.

Kova designs covers for an industry-leading useful lifespan between replacement, which is typically estimated to be well in excess of 1000 years. The useful lifespan is estimated based on extrapolated corrosion rates for stainless steel materials and designing a corrosion allowance into the cover materials

Kova’s on-site engineering staff examine each opening location with local contractors and regulators to mutually agree on the ideal placement for rock anchors and size of each cover. Field information for fabrication drawings is gathered using conventional methods complimented with laser scanning using a Leica ScanStation P40 and proprietary scanning tools to better inform office-based drafting and engineering personnel.

Engineering design is completed using a combination of traditional calculation methods complimented with computer-aided design methods including finite element analysis (FEA). Drafting work considers the organic shapes of the rock formation captured during scanning, and the detailed FEA work. The resulting work product is a fabrication drawing set for the most material and labour efficient, safe and long-lasting cover that is commercially available today.

Kova’s scope for the project included shop inspections during fabrication using visual and liquid penetrant inspection techniques. In addition field inspections following installation and pickling operations are conducted. Kova’s final work product includes a formal report certifying the cover is ready for service.

The typical work schedule includes gathering information during the summer, completing design work and receiving regulatory approval during the fall, fabricating shop components and transporting during the winter, and installing and completing field review in the summer. With submission of a final report and as-constructed drawings in the fall.

This project was started in 2015 and is currently ongoing with 18 covers either installed and field reviewed or slated for installation during the 2018 summer construction season.