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ENMAX Power Corporation Southeast Substation Safety Enhancement Project, AUC Decision 27193-D01-2022

Link to Decision Summarized

Flood Mitigation – Electricity Substation Construction Work – The City of Calgary Land Use Bylaws New Buildings in Floodway


ENMAX Power Corporation (“EPC”) identified an arc-flash hazard from existing outdoor switchgear at its No. 32 Substation that presents a safety concern to employees working at the substation. EPC filed an application with the AUC proposing two options to address the hazard and to mitigate flood risks at the substation.


The AUC found that EPC’s preferred option, to replace the existing outdoor medium voltage switchgear with indoor arc-resistant switchgear inside a new building at the No. 32 Substation site, is in the public interest. The alternative option, to relocate equipment away from the substation, would result in inefficiencies and additional costs.

The AUC approved EPC’s proposed flood mitigation measures by [INSERT – see comment below, I do not know which option the AUC approved]

Applicable Legislation

Alberta Utilities Commission Act, SA 2007, c A-37.2 – s 17.

AUC Rule 007: Applications for Power Plants, Substations, Transmission Lines, Industrial System Designations, Hydro Developments and Gas Utility Pipelines

The City of Calgary Land Use Bylaw

Hydro and Electric Energy Act, RSA 2000, c H-16 – ss 14, 15, 19, and 21.

Municipal Government Act, RSA 2000, c M-26 – Part 17.

Planning Exemption Regulation, Alta Reg 223/2000.

Pertinent Issues

EPC presented two flood mitigation options for both 100- and 350-year levels of flood mitigation. ENMAX’s preferred flood mitigation option was to construct a steel sheet pile wall. The alternate flood mitigation option was to install bank armouring with a self-launching apron design.

The AUC accepted that flood risks exist at the substation. The AUC was satisfied that the Planning Exemption Regulation exempts the facilities proposed as EPC’s preferred option from the city’s bylaw that restricts new buildings in a floodway.

In support of its preferred option, EPC stated that the steel sheet pile wall can be constructed from the riverbank, while the bank armouring option must be constructed in the Bow River. The steel sheet pile wall could thus be permitted and constructed faster than the alternate option. The preferred option also has the least impact on fish habitat.

The AUC approved the alternate option. The AUC determined that the lower cost of the bank armouring and self-launching apron option was a deciding factor, as other factors of the measures were not significantly different. EPC submitted that construction of the sheet pile wall would cost $8.8 million. Costs of the bank armouring and self-launching apron were estimated to be $4.8 million including potential, but not yet identified, fish habitat offsetting requirements.

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