Downtown Edmonton Supply and Substation (DESS) Project

Client

EPCOR Distribution & Transmission

Overview

EPCOR Technologies helped reinforce the energy supply to North Edmonton with the installation of a 10.5 km duct and 240 kV underground cable through the heart of the City.

Challenges

With the decommissioning of Edmonton's Rossdale Power Plant, the local utility was looking to provide additional security for the stable supply of electricity to Edmonton's downtown. A 240 kV connection between the Castle Downs Substation in North Edmonton to the Victoria Substation in downtown Edmonton was deemed to be needed.

The plan posed significant challenges in performing greenfield construction along a 10.5 km stretch through established neighborhoods, roadways and utility crossings. Such an undertaking would require significant planning and traffic accommodation, as well as effective field coordination with multiple subcontractors in numerous areas to be competed safely and efficiently.

To complicate matters further, newly constructed duct would have to be constructed abnormally deep underground to bypass many existing utilities. In some instances up to six metres in depth would be required.

Solution

EPCOR Technologies rose to the challenge, securing the Prime Contract for the project. Utilizing an integrated team of construction workers, equipment operators and safety personnel, our field team performed:

• Trenching
• Directional drilling
• Pipe laying
• Construction of the duct line
• Assembly of 17 large vaults in a confined, sub-ground space
• Cable installation
• Integration support for entry into each substation

In one neighborhood, a 500 metre directional drilling operation was completed to run the cable under the CN Rail switchyards and Yellowhead Trail freeway.

To mitigate the challenge of the required duct depth, crews pulled in 30 inches of steel casing, acting as a race way for the conduct. The conduct consisted of special designed spacers with built in rollers to handle the heavy weights of the bundle of pipes as it was pulled in though the steel casing and then later filled in with a special designed concrete. This concrete was designed to flow around the conduct filling the voids to create strength and dissipate the heat generated by the cables once in operation.

Ultimately safety was treated as the most important aspect of this challenging job, which required working in confined spaces, along crowded city streets and across intersections. EPCOR Technologies' rigorous safety program offered the necessary foundation for safe execution and ensuring sub-contractors conformed to City of Edmonton and EPCOR standards.