Midtown Electricity Infrastructure Renewal (Midtown Project)

Project Description and Need
Hydro One Networks Inc. (Hydro One) and Toronto Hydro-Electric System Limited (Toronto Hydro) have jointly identified a need to refurbish the existing 115 kilovolt (kV) transmission infrastructure which serves midtown and areas to the west. The midtown power corridor which runs from Leaside Transformer Station (TS) via Birch Junction (Jct) to Bridgman TS was originally built in the 1920s and the first underground cable laid in the 1950s. The midtown area has experienced steady load growth as the result of land use intensification and redevelopment. An underground transmission cable located on the transmission corridor is nearing its end of life and the added growth in the area is putting a strain on this important infrastructure and on the reliable supply of power.

The need for the Midtown Project has also been confirmed by the Independent Electricity System Operator and recognized by the Ontario Power Authority as an urgent need to precede the Integrated Power System Plan. In addition, the Ontario Energy Board (OEB) also approved the need in its Decision regarding Hydro One's 2007/2008 Transmission Revenue Requirement and Rate Application.

Maintaining a reliable electricity supply for Midtown Toronto 
In order to ensure that Toronto Hydro customers continue to receive an adequate and reliable supply of electricity, the following needs must be addressed:

• Replace an aging underground cable located between Bayview Junction (Jct) and Birch Jct installed in 1956 which is nearing its end of life.
• Install an additional 115 kV circuit between Leaside Transformer Station (TS) and Birch Jct to relieve loading on the existing circuits which are currently operating above their capacity; and
• Install new equipment at Leaside TS, and Bayview, Birch and Bridgman Junctions.
• Using existing 115 kV overhead circuit between Birch and Bridgman Junctions to supply additional electricial capacity.

These transmission infrastructure refurbishments are intended to reduce the risk of power outages and improve reliability for Toronto Hydro customers.