Project Background & Need
Hydro One's Wilson TS, Thornton TS, Whitby TS and Cherrywood TS have reached their capacity to reliably supply customers in the growing Region of Durham. The need for additional transmission capacity was recently identified in a joint planning study between Hydro One Networks and the Local Distribution Utilities serving Durham Region. The new electrical transmission facilities will accommodate the anticipated electricity load growth in Oshawa and Clarington and improve reliability of electricity supply to customers in these areas.
Hydro One's objective will be to design and construct this project under the guidelines of the Ontario Environmental Assessment Act.
Preferred Site
Following a consultation process with members of the public, public interest groups, municipal governments and elected officials, an initial preferred site 1a (previously designated as Site A) was selected on Hydro One property — north of Concession Road 7 between Langmaid Road and Grandview Street North in the Municipality of Clarington.
Site gradient was an important factor for the selection of Site 1a. A subsequent geotechnical survey of Site 2 (previously designated as Site B) determined that the water table is about 4 m below grade, whereas the proposed cut is 10 m. As a result, Site 2 was technically unacceptable as a location for the proposed TS.
A number of issues/concerns were raised by some local residents about the Site 1a location including access road location (from Langmaid Road), potential construction effects on groundwater, noise, visual aesthetics, property value effects, among others. These issues/concerns were subsequently communicated to Hydro One at a local community meeting on December 14, 2006.
As a result, two additional alternative sites, i.e., Sites 1b and 1c, were identified on the Hydro One property. Each of the three sites was assessed on the basis of a set of evaluation criteria (environmental, technical, cost) and Site 1c was identified as the preferred site location.
Assessment of Alternatives
Site selection was based on:
- Availability of property
- Proximity to residences
- Effects on natural features
- Effects on social environment
- Potential land use designation restrictions
- Technical and maintenance considerations
- Cost.
The Recommended Site 1c
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Disadvantages |
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Proximity to existing transmission line |
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Highest cost |
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Further distance from residential areas compared to Site 1a |
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Fewer land use restrictions |
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Shortest access road |
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Least agricultural land displacement |
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No access road watercourse crossing |
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Less visual aesthetics effects |
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Better technical/constructability/ maintenance features than Site 1b |
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Proposed Transmission Facilities
The new TS project involves the construction of a 230 kV TS in the vicinity of Harmony Road North and Enfield Road, adjacent to the existing 230 kV transmission corridor. The TS will convert the 230 kV transmission voltage to 44 kV for distribution to homes and businesses in Oshawa and Clarington. The major equipment needed will be:
- Two 230/44 kV transformers
- 44 kV switching facilities
- Associated buswork
- Eight 44 kV distribution feeders.
Next Steps
The planning and analysis supporting the preferred site has been documented in Hydro One's Draft Environmental Study Report (ESR). The ESR is available for a 60-day public review starting on June 17, 2008. Copies are available for download below, or can be obtained from your local public library or municipal office.
