Canada’s Parliament Buildings in Ottawa, built in a soaring Gothic Revival style, form one of the most recognizable sights in the country. The seemingly solid, load-bearing masonry walls are surprisingly fragile so when it came time to renovate buildings dating back to the 1860s, it was important to work in a way that would safeguard this key part of the country’s heritage.
One of the keys to success came through the sound understanding of geotechnical engineering and rock mechanics provided by WSP*. This knowledge was vital in one of the most recent projects in the multi-decade renovation of the Parliament Hill complex – the refurbishment of the West Block. The work was necessary partly to provide a temporary home for the 308-seat House of Commons, Canada’s main elected legislative body, over the next decade, while the nearby Centre Block, containing the Commons’ usual chamber, is being renovated.
To provide interim space for the Commons to meet, the open-air courtyard in the middle of the West Block was excavated down two and a half stories below grade. Various tunnels and other underground structures were built, a floor for the chamber was constructed, and the courtyard provided with a glass roof. For that work to happen in a way that did not damage the 150-year-old building, WSP* undertook the geotechnical investigation and design for the excavation of the courtyard. The team had to contend with highly faulted limestone rock under the building, and devise ways for the excavation to be done while guarding against any shifting of the rock that might cause fractures or collapses in the masonry walls overhead.
Proof of WSP*’s success in excavation and design can be seen in the fact that construction of the new chamber proceeded smoothly, without the issues that are all too frequent in underground projects. The work called upon a wide range of expertise within WSP*, including geotechnical engineering, rock mechanics, geophysics and environmental science.
WSP* also brought knowledgeable archaeologists to the team to ensure that the work was done in a way that protected and documented any archaeological resources on site. This was doubly important because prior to European contact, Indigenous Peoples had utilized the Ottawa River and its many tributaries for ease of movement on the landscape. Evidence of an Indigenous settlement was previously uncovered on this high, windswept hill overlooking the Ottawa River. Later, the hill was the site of a British military fortification called Barracks Hill, traces of which remain around the modern-day Parliament Hill. WSP*’s role included watching for and documenting evidence of these previous uses of the site as well as checking for artifacts from the West Block’s own history, including water piping and heating and cooling systems from the 1800s and early 1900s.
The West Block project is not WSP*’s first venture under the stone buildings of Parliament Hill. WSP* received an Award of Excellence in 2004 for supporting the underground expansion of the Library of Parliament building beside the Centre Block. From 1996 to 1998, WSP* helped expand the basement underneath the Centre Block itself. WSP*’s role was to design the excavation for the underground space to accommodate the required equipment and services, and to engineer the rock excavation procedures and controls.
The refurbishment of the West Block is now nearly complete, providing a new home for Canada’s legislators.
For more coverage of this important project, read Canadian Architect’s article “House Leader: West Block Rehabilitation Project, Parliament Hill, Ottawa, Ontario” and check out these time lapse videos that show 7 years of restoration and modernization work at the West Block. Short version | Long version
* This work was performed by Golder professionals who joined WSP in an acquisition completed in 2021.