News Release

1:15 p.m. PDT – Wednesday, July 13

VANCOUVER – With water levels expected to rise and crest today and tomorrow on the south Fraser River, BC Hydro is continuing to stabilize a 500-kilovolt transmission tower and the surrounding area on the south side of the river that has been impacted by apparent erosion caused by high river flows.

Immediate priorities

• Stabilizing the de-energized 500-kilovolt on the south side by placing riprap (loose rocks and boulders)  in the most vulnerable areas;
• Taking measures to prevent continued sloughing on CN's dike and road adjacent to the 500-kilovolt tower by burying the fallen 230-kilovolt tower – which is submerged in the water alongside the dyke and road – with riprap rather than salvaging the fallen tower from the river;
• In addition to safety measures already in place, continuing to develop precautionary measures to enhance the safety of the 500-kilovolt system on and adjacent to the river, which could include the removal of select spans of the de-energized 500-kilovolt conductors (power lines);
• Continued around-the-clock monitoring and assessment.

Stabilizing the 500-kilovolt tower on the south side and mitigating against further erosion of the CN dyke/road using the fallen 230-kilovolt tower

• BC Hydro and CN have recorded additional sloughing along CN's dike and road located downstream from the 500-kV tower. This is likely due to erosion caused by high river flows.
• The 500-kV tower has not moved since Friday, July 8 and the most recent geotechnical assessments taken late Tuesday afternoon indicate no further risk to the tower.
• However, to ensure maximum safety and to prevent further erosion to the dike and road, BC Hydro has decided not to salvage the 230-kilovolt tower that fell into the river on July 4th. Instead the tower will temporarily remain in the river, covered with riprap in order to help stabilize the river bank. BC Hydro and CN will determine with authorities, at a later date, whether the tower can be removed.
• To do this, riprap will first be piled on the river side (north) of the fallen tower, then further riprap will be placed on and between the lattice (structural criss-crossed framework) of the tower, covering a significant amount of the 200,000 pound, 20-story tower.
• Over the past two days, BC Hydro has placed 900 cubic metres of riprap around the foundation of the 500-kV tower. With that work complete, today, BC Hydro will continue to add additional riprap to the most vulnerable areas. In total, three barges full of riprap will have been placed on the site to date. BC hydro and CN engineers will continually assess the vulnerable areas and adjust riprap placement as necessary.
• This week, BC Hydro continues to assess the feasibility of additional precautionary safety measures, which could include the removal of select spans of the de-energized 500-kilovolt conductors (power lines).
• Last week, BC Hydro successfully installed additional guy wiring (support wiring) on the 500-kilovolt tower on the south side of the river, as a precautionary measure, and repositioned existing wiring to enhance stability. Crews also installed guy wiring as a precautionary measure to the 500-kilovolt tower on the north side of the river. This was done to further enhance safety and prevent potential disruption to the public should the tower on the south side fall.

River levels, monitoring and assessments

• BC Hydro continues to monitor the stability of the 500-kilovolt and 230-kilovolt towers around-the-clock.
• River flow estimates forecast an increase in Fraser River water levels over the next 24 hours due to heavy rains and flooding in the Peace region of B.C.
• While forecasts suggest that the river will have reached its peak at approximately 12 noon today, river currents and their velocity have the most impact on erosion.
• In addition to the bathymetric equipment used to observe the foundation of the river bed, specialists are also using surveying equipment with laser technology to detect any movement of the tower above ground and to determine the tension on the supporting wires of the tower.

For further background, please visit www.bchydro.com/mediabulletins.

For more information

BC Hydro Media Relations
Phone: 604 928 6468