The Chilliwack Cable Replacement Project has involved:
- Excavating along Cheam Ave. between the manholes located at the north side of the Safeway Parking lot, and the alley into the substation behind Dairy Queen, to remove one set of old cables. Excavation is taking place in the sidewalk on the north side of Cheam Ave in order to remove the cables from the other old circuit.
- Forming and installing duct banks in the same locations
- Repaving Cheam Ave and installing a new sidewalk along the north side
- Undertaking similar work up the alley leading to the substation
This work is now completed. In early 2010 the final part of the project involves:
- Pulling the new cables into place. Each circuit comprises three cables.
- Splicing the new cables in the manholes and connecting them at the substation
- Testing each cable
- Removing temporary overhead circuits
Protecting Chilliwack’s electricity supply
Chilliwack depends on Chilliwack Substation and on the cables that feed the substation for its electricity supply. In planning this project, we looked for ways to minimize any risk to Chilliwack’s electricity supply during project construction.
The decision was made to supply Chilliwack substation during project construction by installing a short overhead 69 kilovolt (kV) double circuit. This is a temporary installation. The overhead circuits will be removed as soon as the new cables are fully tested and put into service.
The advantages of this system are:
- Risk of an outage is minimized. If an overhead circuit had not been used, then repeated planned outages would have had to be taken on the existing cable circuits throughout the project, in order for the work to be undertaken safely. During each outage, the electricity supply to Chilliwack Substation would be completely dependent on one circuit. Should there be a malfunction or accidental damage to the remaining circuit, Chilliwack would experience a complete power outage.
With the overhead circuits in place, no planned outages are required.
- Excavation of Cheam Ave. is minimized. If an overhead circuit had not been used, then excavation of Cheam Ave. would have to take place first to install the new duct banks and then, many months later, Cheam Ave. would need to be excavated again to remove the old cables.
With the overhead circuits in place, Cheam Ave. was excavated only once, as the old cables were removed as the new duct banks were installed.