BC Hydro update #12: Proposed Restoration Plans for Fraser River Transmission Towers
12 p.m. – Wednesday, Aug. 10
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VANCOUVER – BC Hydro today released proposed restoration plans for the two transmission crossings over the Fraser River near the Port Mann Bridge. BC Hydro has been working for several weeks to stabilize the affected towers and transmission lines. The restoration work will allow the lines to be re-energized to provide a safe and reliable supply of electricity for storm season and the winter peak; and provide for a stronger and more reliable solution in the long-term.
Restoration plans – 230-kilovolt line (fallen tower)
BC Hydro proposes to install a high-tension, low-sag composite transmission line across the river that will be carried from the tower on the north side of the river to a tower further south and inland from the fallen tower. By using these specialized lines and stronger towers, the fallen tower would not require replacement as the new lines can be suspended over a longer span. BC Hydro crews will begin this work in mid-September and expect its completion by November.
Restoration plans – 500-kilovolt line (leaning tower)
After stabilizing the 500-kilovolt tower on the south side of the Fraser River, BC Hydro will safely energize the 500-kilovolt lines in time for the winter season. Efforts to stabilize the leaning tower over the past weeks have included:
- placing 40,000 tonnes of riprap at the base of the tower on the river bed to reinforce the foundation using cranes on barges;
- attaching guy wires from the ground to the waist of the tower;
- installing guy wires between the leaning tower and the next closest inland tower (1,743 feet away) using a low-flying helicopter; and
- driving eight 100-foot-high steel piles 36-feet into the river bed to support the footings of the tower.
Next spring after the winter peak season, BC Hydro plans to replace the existing lines on the 500-kilovolt tower using the same high-tension, low sag lines used for the 230-kilovolt system to eliminate the need for this tower completely. The tower would then be dismantled because it would no longer be required to support the new lines.
Background
Two separate transmission lines cross the Fraser River near the Port Mann Bridge: a 230-kilovolt line and a 500-kilovolt line. Both sets of lines are currently de-energized.
- 230-kilovolt line: a transmission tower on the south side of the river carrying the 230-kilovolt line fell into the river on July 4 after its foundation was compromised, likely due to accelerated erosion caused by high river levels.
- 500-kilovolt line: BC Hydro has been monitoring and stabilizing a tower carrying the 500-kilovolt line, also on the south side of the river, since mid-June after the tower was damaged and further destabilized by high water flows.
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For more information
BC Hydro Media Relations
p. 604.928.6468