Emergency Response to multiple tower damage on A1B/A2B Transmission Line

Emergency Response to multiple tower damage on A1B/A2B Transmission Line

Client: SaskPower

Owner: SaskPower

Project Status: Complete

Location: Wakaw, Saskatchewan

Voltage: 230Kv Double Circuit

Category: Emergency restoration

The project

In December of 2014, heavy ice loading caused broken Shield Wire and damaged the OHSW tower wings requiring wing replacements and replacement of 7.5km of double shield wire. SaskPower called Allteck during the Christmas Holiday for emergency repairs to the 230kV double circuit steel towers damaged due to ice.

This circuit is one of the main feeds in the Province and limited outages were available. All the wing replacements and conductor installation were completed with 1 circuit energized, while working on the opposite sides of the towers. Allteck removed and replaced 35 shield wire wings on these towers, and re-installed 7.5km of 2 X 5/16” shield wire.

In April of 2015, a tower on the same circuit was having foundation work completed by another contractor when the tower footings collapsed and the tower fell over. At 2 am SaskPower called Allteck and within hours crews arrived to find the tower leaning at a 45 degree angle with the conductors energized and 10’ from the ground. Circuits were de-energized and the tower was stabilized. Allteck set a temporary pole mid-span to prevent damage to the adjacent structures and prepare one circuit for re-energization so as to prepare for other possible circuit failures in the Province.

Allteck worked with a screw pile contractor who installed new screw pile foundations adjacent to the existing location and a new tower base was assembled and installed on the screw piles. A 400 ton crane was brought in, the leaning tower was cut off, the undamaged tower was straightened and swung over to the new base with all conductors in travellers and still attached to the tower.

The Challenges

Winter conditions led to many logistical challenges including bad road conditions, equipment issues and freezing rain had towers covered in ice.

SaskPower assigned Allteck’s Project Manager as the Operations Field Commander who led the repair and replacement of the damaged components. The Allteck Project Manager was imbedded in the Saskpower Incident Command Team.

Specialized Work Procedures

Because of security issues and the possibility of additional tower failures, Allteck established a 24 hour monitoring program and a safety perimeter to protect SaskPower’s assets and to maintain public safety.

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