Wing Wall Rehabilitation at Suncor Plant 85
The mechanically stabilized earth walls at Suncor’s oil sands facility were well beyond their designed 10-year life and were showing signs of deterioration. The company evaluated the possibility of extending the life of the walls by stabilizing them with soil nails, engaging a Tetra Tech geotechnical design team to review the soil nail design scheme.
Our geotechnical leads visited the site to evaluate three in-place mechanically stabilized earth walls and discuss with Suncor and a contractor group the potential remedial actions necessary to prolong the life of the walls. Tetra Tech then reviewed documentation and data available from Suncor and prepared a preliminary design review document that incorporated comments from all stakeholders. Suncor reviewed and accepted the design; Tetra Tech continued to provide design support and field construction monitoring services for the duration of construction.
Survey data were lacking, so Tetra Tech used a field-fit design for the wall rehabilitation. Because of the geotechnical complexity of the project and the requirement for our engineers to sign off on construction of the rehabilitation measures, Tetra Tech proposed putting full-time on-site inspectors in place to observe the soil nail testing and installation, as well as the shotcreteing of the wall surfaces.
During construction, Tetra Tech was highly interactive in observing the construction and discussing with the client and contractors site issues regarding changes and field-fit areas. Many of these changes had beneficial effects on the construction program, and therefore they often resulted in time or cost savings. Because variable soil was observed in back of the wall, various drilling methods were incorporated to effectively install the soil nails. Verification nails were designed throughout the wall to ensure the design loads were achieved. Tetra Tech confirmed that the construction materials used met the specified properties by performing laboratory testing. Tetra Tech documented the installation methods and reported all applicable information.