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​Project overview

An underground electrical transmission line that runs along Calgary Trail from the Rossdale Substation (9469 Rossdale Road) to the Strathcona Substation (5140 - 99 Street) has reached the end of its useful life and needs to be removed. This transmission line was taken out of service in November 2020 after a new transmission line was built in southeast Edmonton.

The transmission line is made up of a single, three-phase cable. Once the cable is removed, the steel pipe will be cleaned so that it can be used for other electrical utilities.

Decommissioning process

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Construction impacts

How you're impacted

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Schedule and map

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Regulatory requirements

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  Decommissioning process

There are several steps in decommissioning an underground transmission line. These steps are outlined below:

Step 1 – Drain the insulating fluid

Some underground transmission cables are contained in oil. The oil acts as an insulator, which does not conduct electricity and helps transfer heat away from the cables to keep them from overheating. Before the transmission cables can be removed, the oil must be drained.  The majority of the oil will be drained at the Rossdale Substation. The remaining oil will be drained from the utility access point just south of the Rossdale Substation, which is the lowest access point along the line.

Step 2 – Pull out the cable

Once the insulating fluid has been drained, the cable will be removed. This will involve going into utility access points along the route and pulling out the cable using a winch. Once the cable is pulled out, the steel pipe that the cable is contained in will be cleaned.  Lined containers will collect any oil that comes out during the removal of the cable.

Step 3 – Clean the pipe

Underground electrical utilities are sometimes contained in a steel pipe. Steel pipes protect the cables from being damaged. Once the cable has been removed, the pipe will be cleaned so it can be re-used for other EPCOR electrical utilities. Part of this pipe will be re-used for a fibre optic line. Find out more information on our Fibre Optic Cable Project.

  Construction impacts

You may notice localized traffic and sidewalk impacts as crews set up at various utility access points along the route to remove the old cable that makes up the underground transmission line. Signs will be used to detour traffic and pedestrians around the worksites.

  Schedule and map

Fall 2021 – Drain the insulating fluid (step one).

Winter/Spring 2022 – Remove the transmission cables and clean the pipe (step 3) at each utility access point. Locations of the utility access points are shown on the map.

Project map

 

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  Regulatory requirements

Alberta's electrical system is regulated by the AUC. The AUC is an independent, quasi-judicial agency that ensures the delivery of Alberta's utility services takes place in a manner that is fair, responsible and in the public interest. For more information about the AUC, please visit the AUC's website.

 

Definitions

Transmission lines (cables) carry high-voltage electricity to different EPCOR substations throughout Edmonton. Substations then convert the electricity from the higher voltage transmission lines to lower voltages, so it can be used by homes and businesses using distribution lines.

EPCOR's transmission fibre optic lines provide a communications link between neighboring substations and EPCOR's control center. This enables EPCOR to monitor and remotely control its transmission equipment, communicate with other transmission operators, and ensure the safety and reliability of EPCOR's transmission system.