Located adjacent to the iconic, and first-ever Tim Horton’s store in Hamilton’s east end, construction continues for YWCA’s new 6-storey affordable housing project on Ottawa Street North. Utilizing passive house design, this building aims to achieve an overall energy savings of 75% also to reduce greenhouse gas emissions by more than 25%. An ambitious target for sure. This innovative new building will provide safe and affordable housing for 50 women and women-led families and includes 15 unique units geared toward women with a range of developmental disabilities.
This important project was designed by Kearns Mancini Architects and RJC Engineers and was built by Schilthuis Construction, who are considered leaders in Passive House design and construction. All units and common areas of the building will be fully accessible with 10 units being barrier-free. The building will also incorporate a multifunctional seniors centre with a dedicated kitchen on the ground floor and a treed exterior and community garden.
As is the case with most projects, and especially with affordable housing projects, finding the most cost-effective foundation solution was critical to making this structure a reality. The low capacity of the native silt/clay soils was driving the foundation design towards a large raft or deep foundation system that would add major cost to this largely government-funded project and create complications in terms of the Passive House utility requirements. Utilities would have had to be buried within the raft, which is not something designers are keen to do as access to utilities for future repairs is an important consideration. As such, the granular layer and false slab that would have had to be designed to house the utilities above the raft would have pushed the raft elevation far deeper than sensible. Construction was further hampered by constrained site conditions and access in a very busy urban area.
By working closely with RJC Engineers and Schilthuis Construction, GeoSolv’s ground improvement experts designed a Geopier Rammed Aggregate Pier® system (GP3) to reinforce the silt/clay soils, providing an improved ultimate bearing capacity of up to 450 kPa. The full-scale load test, conducted on a test pier in the poorest borehole location possible on site, using the highest pier stress at any location, resulted in <12mm of settlement at 100% design load.
The Geopier system significantly reduced the footing sizes while facilitating engineered settlement control for the structure. High capacity strip/spread footings allowed for greater clearance in between footings for the below structure utilities and helped to reduce excavation costs.
Aside from the many benefits offered using Geopier and footings vs the massive raft design, a key aspect of this project was the close involvement of GeoSolv with the project design team to help overcome their technical challenges as the designed progressed to 100%. GeoSolv further coordinated closely with the General Contractor, Schilthuis, to ensure that construction went smoothly, both during and after our work.
Ultimately, the Geopier system was successfully installed from multiple working elevations and was thoroughly tested to meet and exceed the requirements of the project. The Geopier system, as a ground improvement method, did not require any foundation permits prior to installation, which offered significant schedule savings and helped to deliver this much-needed project to the community. Check out this short clip of us on-site and in action!
We are honoured for the opportunity to play a role in supporting the Hamilton community.