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ENMAX Power Corporation – Highway 8 Transmission Line 138-7.82L Relocation Project, AUC Decision 24831-D01-2020

Link to Decision Summarized

Facilities – Transmission Line

In this decision, the AUC considered an application from ENMAX Power Corporation (“ENMAX”) to alter and operate Transmission Line 138-7.82L near Highway 8 in the southwest quadrant of the City of Calgary. The AUC found that approval of ENMAX’s preferred route was in the public interest, having regard to the social and economic effects of the project and its effect on the environment, in accordance with Section 17 of the Alberta Utilities Commission Act (“AUCA”).

Introduction and Background

ENMAX is the owner of Transmission Line 138-7.82L, which is located in the Calgary transportation and utility corridor (“TUC”) and its current location conflicts with the construction and planned infrastructure of the West Calgary Ring Road (“WCRR”). Alberta Transportation directed ENMAX to relocate certain portions of the line to accommodate the WCRR construction.

ENMAX applied to the AUC for approval under sections 14, 15, and 21 of the Hydro and Electric Energy Act (“HEEA”) to alter, remove and relocate a portion of Transmission Line 138-7.82L near Highway 8 in the City of Calgary. ENMAX applied for approval of one of its two proposed routes, the south-central route (in yellow) and the north route (in pink), as shown in the figure below, as the proposed preferred and alternate routes, respectively.



ENMAX designated the south-central route as its preferred route based on its assessment of impacts on stakeholders and the environment. For the south-central route, ENMAX requested approval to remove 16 existing wood poles, to construct approximately 1.8 kilometres of overhead single-circuit 138-kV line, and to install 13 new steel structures.

ENMAX designated the north route as its alternate route. For the north route, ENMAX requested approval to remove 34 structures of the existing line, to construct approximately 2.9 kilometres of overhead single-circuit 138-kV line, and to install 25 new single-circuit self-supporting steel monopoles.

The proposed structures on both routes would range in height from 18 to 33 metres, resulting in an increase in height from the existing wood poles, which are between 19 and 26 metres tall.

ENMAX estimated the cost of the south-central route at $3.91 million, and the estimated cost of the north route at $6.24 million.

Interventions and Standing

The AUC received statements of intent to participate from local residents and landowners, and from the Slopes Community Association (“SCA”), the Springbank Hill Community Association (“SBHCA”), the Discovery Ridge Community Association (“DRCA”) and the Pinebrook Estates Homeowners Association (that later joined with an individual to become the Mortimer / Pinebrook Group). The SCA/SBHCA retained Trevor Cline to provide evidence on their behalf.

The issues raised in the statements of intent to participate mainly focused on the routing of the relocated line and residential impacts. The AUC granted standing to the above-captioned groups and several individuals.


ENMAX retained Maskwa Environmental Consulting Ltd. (“Maskwa”) to conduct the routing assessment for the project and identify potential routes with the lowest impact. Maskwa determined the south-central route to be the preferred route based on its lower overall impacts when compared to the north route. The north route was identified as the alternate route.

ENMAX concluded that both the preferred and alternate routes were viable and comparable, avoid or minimize potential negative impacts, and are located within the TUC.

Temporary Options to Retain the Existing Line

Mr. Cline prepared a report that concluded that ENMAX could retain the existing line route by either: (a) constructing a temporary line for use during WCRR construction, or (b) constructing a temporary alternate connection to supply customers during WCRR construction.

The AUC rejected these alternatives, noting that the temporary supply alternative would require the AESO to submit a needs identification document application. Both alternatives would require portions of the permanent line route, including structures, to be located in the exclusion zone within which Alberta Transportation specifically stated transmission structures are not permitted.

All-dielectric Self-supporting Proposal

Mr. Cline proposed a modification to the south-central route to address stakeholder concerns about visual impacts related to the larger and taller poles. He stated that the height of the poles is governed by the all-dielectric self-supporting (“ADSS”) fibre-optic cable because it is the lowest cable on the structures. He suggested that removing the ADSS cable from the poles and burying it underground would result in the lowest transmission conductor governing pole height, which would allow for an approximately 1.5-metre reduction in the height of the structures.

The AUC rejected this suggestion, accepting ENMAX’s evidence that burying the ADSS cable would increase the risk to customer reliability, given the additional transition points that would be required in the system.

Need for Future Substation 45

The Mortimer Pinebrook Group retained Pablo Argenal of Nican International Consulting Ltd. to prepare a report that included a historical review of publicly available transmission and distribution planning information relating to Transmission Line 138-7.82L. Mr. Argenal concluded that since approximately 1993, ENMAX has been aware of the need for a future substation, referred to as Substation 45, to be located in proximity to the proposed project.

Mr. Argenal submitted that Substation 45 would be required to provide sufficient backup through the distribution system if there is an N-1 or N-2 outage at an existing substation. He submitted that the north route aligns well with the previously identified Substation 45 location and that this is a relevant factor in favour of approval of the north route.

The AUC considered Mr. Argenal’s assertion that there will be a need for a future substation in the TUC to serve increasing load levels in the west Calgary area and that this need should favour the north route for the relocation of Transmission Line 138-7.82L. However, the AUC was satisfied that ENMAX has a plan to reliably serve area load for the next ten years, including by undertaking the recent upgrades to Substation No. 7. It was also satisfied that ENMAX has reasonably considered other options for serving load growth beyond the 10-year period that do not require a new substation within the TUC.

Historical Approval of the Line Route

The DRCA referred to policy documents that indicated that the ring road would require the positioning of the relocated line on the north side of Highway 8. The AUC rejected the assertion that the decision had already been made by authorities that Transmission Line 138-7.82L must be routed north of Highway 8 when its relocation was required for WCRR construction.

Residential Impacts

The AUC accepted ENMAX’s conclusion that both routes have comparable but not identical residential impacts, and in particular, that no residence would be within 50 metres of a newly built portion of the line on either route.

The AUC accepted that the south-central route uses more of the existing transmission line alignment than the north route and considered this to be one of the two factors that favours approval of the south-central route. The other factor is the lower cost to construct the south-central route.

Participant Involvement Program

The AUC found that ENMAX satisfied the notice and consultation requirements of Rule 007. The AUC was satisfied that residents along both routes were sufficiently engaged by ENMAX in project development and accepted that ENMAX incorporated stakeholder feedback wherever feasible.


The AUC found that both routes would have minimal potential negative impacts on the environment. Both routes would be located entirely within the TUC, which is land designated by the Government of Alberta for major linear facilities such as roads and transmission lines.

Project Cost

The AUC accepted ENMAX’s cost estimates and observed that the estimate for the south-central route is approximately 38 percent less than the estimate for the north route. The AUC further understood that the shorter length of new build or rebuild on the south-central route is the most significant factor in the difference in cost estimates between the two routes, and was satisfied that relocating the line to the south-central route would be less costly than relocating it to the north route.


The AUC found that relocating Transmission Line 138-7.82L to the south-central route, including salvaging portions of the existing line, is in the public interest pursuant to Section 17 of the AUCA.

Pursuant to sections 14, 15, 19, and 21 of HEEA, the AUC approved the application. The AUC noted that the facilities in this application would all be located within the TUC. Under the Calgary Restricted Development Area Regulations, the AUC cannot issue a permit and licence for the construction and operation of facilities within the TUC without the written consent of the Minister of Infrastructure. The permit and licence for the project will, therefore, be issued once the written consent of the Minister of Infrastructure has been filed with the AUC.

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