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The 157-year-old Point Clark Lighthouse on the shores of Lake Huron at Huron-Kinloss Township is finally getting the makeover it was promised years ago.
Limen Group Const. Ltd. will complete the year-long restoration of the 110-foot tall limestone tower this summer.
This restoration will please locals and tourists because the landmark lighthouse — designated a national heritage site in 1966 — and its museum have been closed for some years. The light, however, has remained in service over that time and continues to serve maritime traffic throughout the restoration project.
While there has been previous work to the lighthouse, Limen’s scope of work will conserve and bolster the structure for years to come. Parks Canada is the actual owner and the project is being managed by Public Works and Government Services Canada.
The most unusual element of Limen’s restoration contract is pressure grouting the inner core of the tower to consolidate the walls, which are in “an advanced state of deterioration,” explains Arran Brannigan, vice-president of operations.
The process entails an injection of hydraulic lime grout through port holes at masonry joints. The holes were drilled in each course and plastic tubes inserted to transport mortar to fill voids in the inner wythe rubble core walls, he says. The low pressure injection (10-15 psi) ensures that the weakened walls don’t sustain further damage.
The injection process was performed starting from the base of the lighthouse and working up, with two crews operating from scaffolding on opposite sides of the tower and working in a counterclockwise direction.
“It is a fairly unique way to do the consolidation process,” says Brannigan, whose firm has plenty of heritage restoration experience.
At the lantern courses near the top of the tower, the exterior walls had to be strapped to pull the pressure “into the building,” while inside the lighthouse shoring and bracing helped “to push it out.” The idea was to “stiffen” the structure prior to grout injection to prevent the walls from “bulging out or pushing in,” he points out.
Installing the scaffolding in itself was tricky because of the round shape of the tower. “We had to assemble it square and then build off pie-shaped inner corners.”
Other responsibilities for the masonry contractor include: replacement of about 400 units of limestone stones; Dutchmen repairs to damaged limestone; crack repairs; and repointing the entire structure with soft lime mortar.
“As conservation best practices were applied, we had to try and conserve or salvage materials where possible.” But to replace limestone units beyond repair, Limen had some help. “The existing limestone was tested and its properties were provided in the contract specifications.”
Limen sourced a compatible replacement stone called Eramosa limestone from a quarry in nearby Wiarton, Ont.
“Quite a few Dutchmen repairs” were required, says Brannigan. The repairs involved cutting out damaged sections of individual limestone pieces and anchoring in new pieces with stainless steel spiral dowels, says Brannigan. Large cracks were filled with hydraulic lime mortar; small cracks with epoxy.
John G. Cooke & Associates Ltd., of Ottawa, was retained for the structural design and engineering of the specialized masonry shoring and bracing required for the project.
The 110-foot tower, one of the taller lighthouses in Ontario, is being completely repointed with a hydraulic lime mortar, he adds.
The lighthouse’s location typically faces harsh weather so the complete structure is enclosed in tarps which allows the team to work in all types of weather.
Constructed over two years, the lighthouse was completed in 1859. It was the first lighthouse in Ontario to achieve a national heritage designation.
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