McVittie Generating Station Roof Replacement

McVittie Generating Station Roof Replacement

‍

In 2019, TESC was approved as a Vendor of Record for civil, mechanical, and electrical construction services for the Northeast Region for Ontario Power Generation. TESC was awarded the replacement of the Powerhouse roofs and associated work at McVittie Generating Station, located 32km southeast of Sudbury, Ontario in July 2020.

‍

TESC was responsible for the following:

‍

• Mobilize and erect temporary barriers/signage to define the Site
• Provide roof drainage during construction to prevent ponding water and hoarding to protect water from entering the building during the replacement of the roof.
• Protection and temporary support of existing adjacent structures/properties, services, and utilities.
• Relocate or temporarily remove existing services and utilities;
• Remove and dispose of the existing ceiling lights in the Powerhouse;
• Remove and dispose of the asbestos containing panels on the ceiling of the Powerhouse.
• Remove loose paint in the southwest corner of the mezzanine to prepare surfaces for new paint.
• Powerhouse Roof Replacement:

• Removal and disposal of existing built-up asphalt roofing membrane system down to existing wood deck. Remove existing metal cap flashings.
• Removal and disposal of the existing wood decking and wood framed ceiling structure down to the existing steel beams.
• Supply and install new structural steel roof beams and supports.
• Supply and install new metal roof deck.
• Supply and install a new fully adhered EPDM roofing membrane system.
• Remove the existing roof drain and associated piping and supply and install two new roof drains and associated piping.
• Provide installation review of roofing by roofing manufacturer.
• Supply and install new overflow roof scuppers.
• Supply and install new prefinished metal cap flashings.
• Supply and install new rubber walkway pads.
• Test all roof drains to ensure they drain as intended.

‍

• Three Downstream Roof Replacements

• Removal and disposal of existing built-up asphalt roofing membrane system down to existing concrete deck. Remove existing metal cap flashings.
• Supply and install a new fully adhered EPDM roofing membrane system.
• Supply and install new drain inserts.
• Provide installation review of roofing by roofing manufacturer.
• Supply and install new prefinished metal cap flashings.
• Supply and install new rubber walkway pads.
• Test all roof drains to ensure they drain as intended.

‍

• Miscellaneous Components Related to Roof:

• Removal and disposal of existing exterior metal roof access ladder and platform from ground to Powerhouse roof.
• Supply and install new metal exterior roof access ladder and platform from the ground to the Powerhouse roof.
• Supply and install exterior access ladders from the Powerhouse roof to each of the three smaller downstream roofs.
• Supply and install ballasted perimeter guardrails on the Powerhouse roof and two of the smaller roofs.
• Supply and install fall arrest anchors on one of the smaller roofs.
• Supply and install a davit rescue system on the Powerhouse roof.
• Supply and install an Electrical Non Conductive Fence on a portion of the Powerhouse Roof and the centre small roof.

‍

• Electrical Grounding of Roofing Components: Provide grounding for guardrail, access ladders and cap flashing and tie into structural steel at 100’ maximum intervals.
• Lighting: Supply and install new ceiling LED lighting in the Powerhouse and associated work.
• Interior Painting:

• Powerhouse ceiling: Prepare the existing roof beams to accept new paint. Primer and paint existing roof beams, new roof beams and supports and the new metal roof deck.
• Paint the walls and ceiling in the southwest corner of mezzanine.

• Emergency Generator Exhaust: Modify the exterior exhaust pipe on the exterior downstream wall.

‍

During the project, it was discovered that the structural Integrity of the walls was inadequate at the point where the beams were going to be connected as the concrete was scaling and falling apart. To maintain schedule, the TESC team ordered the beams longer than required to give the engineers time to determine the detail and then the team cut the beams on site as per the new details provided by the engineers. Despite this challenge, the project was successfully completed on time and on budget, without injuries.