The West Fort McMurray (WFMAC) 500 kV Transmission Line Project includes over 310 miles of high voltage transmission line, expansion of the existing Livock substation, and construction of the new Thickwood Hills substation, all located in Northcentral Alberta. The project is expected to be in-service by mid-2019.
Substation Foundation VE
Bid level foundation designs completed by outside parties included over 1,600 driven piles between the two substations, totaling approximately 1,800 tons of steel. The majority were grouped together to support concrete containment structures. Preliminary slab designs included a deep perimeter beam supported on piles anchored with welded studs at the pile head for concrete anchorage, and an 8-inch-thick concrete slab on a metal deck infill.
Valard requested QS complete value engineering to determine if efficiencies were possible. QS collaborated with the project team to refine designs, creating both cost and schedule savings. This was completed utilizing a self-performed geotechnical study of the substations along with a desktop study done as part of QS’s transmission line work on the project. Soil profiles were developed and applied to structures within the substations.
The containment structure support system was redesigned as a monolithic concrete slab with typical 12-inch thickness and isolated areas of thickened drop-slab construction. Pile sizes and layouts were optimized based on pile axial resistance, and slab reinforcing was tailored to accommodate the layout.
The slab uniformity enabled construction in a single phase, and the revised pile layout allowed for fewer piles and a reduced total tonnage. Ultimately, just under 1,000 piles totaling 1,575 tons were installed, equating to an approximate 40% reduction in piles and 20% reduction in steel.
During construction, QS was responsible for onsite quality assurance of the contractor’s quality control program. Additionally, QS developed and submitted a compliance report that documented the installation logs and any testing and inspection requirements.