South LRT Tunnel and Portal

Client: Stantec Consulting Ltd. / City of Edmonton

UMA was retained by Stantec Consulting Ltd., program managers for the City of Edmonton, to provide conceptual, preliminary and detailed design for this $30 million tunnel and portal. 

The project included two six-metre diameter, 300-metre long tunnels, an 80-metre-long cut-and-cover arch tunnel section and a 110-metre-long retaining wall transition to the surface.  The tunnels passed under a major utility corridor, the Education Car Park and St. Joseph’s College.

Some of the challenges UMA overcame on this project included:

• Difficult geotechnical conditions including outwash sand with layers of silt and glacial till with zones of saturated intra-till sands.
• Complex geometry with a 6% vertical grade and 250 metre radius horizontal curve.
• Protection of existing buildings and utilities against excessive settlements during tunnelling.
• The need to attract national/international tunnelling expertise to compete for a relatively small project.