During the summer of 2016 Cameco plans to do further remediation work on an area of unstable ground at the site of the former Ace underground mine.
Ground slumping was first noticed in October 2013 by a Cameco consultant. At that time, warning flyers were circulated in the mailboxes of Uranium City residents. Ever since, the area has been cordoned off with fencing and warning signs placed to prevent people from inadvertently travelling over the area.
The Ace mine was a relatively shallow underground mine. The ground between the underground mine workings and the surface is called the crown pillar. Since the slumping was discovered, a geo-technical assessment has been conducted on the crown pillar and a remediation plan has been proposed. The assessment work included use of ground penetrating radar (GPR) and drilling through the existing crown pillar. The GPR was used to map the Ace Mine crown pillar along with other underground mining areas associated with the Beaverlodge site. Drilling was completed to help determine the type of rock and the thickness of the crown pillar to help gauge the strength of the rock and the need for additional remediation in this area. The assessment work did not find similar areas of weakened ground outside of the Ace area.
The remediation plan is currently being discussed with the regulatory agencies. The work will be supervised by Cameco geo-technical consultants and the area will be monitored in subsequent year to ensure the ground is now stable.
Warning signs and fencing remain in place to ensure access is limited. Residents and seasonal visitors to Uranium City are reminded to avoid the area and obey all warning signs.