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Description: Built in 1933, the Glenmore Dam is a 30 m high, 300 m long concrete gravity dam on the Elbow River in Calgary, Alberta, that impounds the Glenmore Reservoir. The reservoir is Calgary’s source of drinking water and, together with the dam, prevents flooding of homes and businesses downstream. The structures are also public amenities, providing recreational boating opportunities as well as a pedestrian and cycling pathway over the dam bridge deck. KCB was retained by the City to rehabilitate the dam and replace the bridge deck as part of the larger Glenmore Dam Infrastructure Improvement Program. The goals were to increase the storage capacity of the reservoir for a more resilient, year-round supply of drinking water; to lower the flood risk downstream of the dam; and to enhance the features of the bridge deck, which forms part of the City’s 27-km cycling and pedestrian pathway around the reservoir and along the Elbow River. The project's consulting firm took an innovative and cost-saving refurbishment approach, which focused on repairing the existing concrete dam and minimized demolition. The design replaced the wooden stop-logs on the dam with computer-controlled steel gates, increasing the height and strength of the system and allowing the storage of an extra 10 billion litres of water. This doubles the volume of water available to the City’s water treatment plant in the low-flow winter months, as well as lowering the flood risk during high-flow periods. The Glenmore Dam is unique because it forms part of the City’s public pathway
Submitted By: Michael Grisdale
City: Calgary
Region: Alberta
Lifespan of the Dam
The rehabilitation of the dam extends its lifespan by 50 or more years.
Dam Strength and Stability
To store higher levels of water and to consider modern day seismic and ice loading, post tensioned (PT) steel rock anchors were added to the weir crest and spillway of the dam.
Water Supply Resiliency
The steel gates can withstand loading from ice and allow operation at full-supply level during the winter months. The gates also have a low leakage rate, meaning less unintentional water loss from the reservoir.
“This project is the first major milestone in providing the protection Calgarians expect. By adding 10 billion additional litres of capacity, we have doubled the protection offered by the Glenmore reservoir, and that is reason for celebration” Mayor Naheed Nenshi said in a September 2020 press release.
Flood Protection
The higher steel gates with independent hoists allow for better management of extreme events. The previous stop-logs could only be operated one at a time, so the system was slow to react to incoming weather patterns. The new gates can be adjusted quickly and remotely during a flood scenario.
The Alberta Minister of Environment and Parks, said in a September 2020 press release: “The upgrades at Glenmore Dam will bring peace of mind to those living and working downstream and help avoid disruption to lives and livelihoods during severe weather events.”
Recreational Experience
A new and wider bridge deck, improved lighting, and aesthetic details improve the experience of cyclists and pedestrians.
The Glenmore Dam Rehabilitation project was completed on time and was operational by the summer of 2020, as required by the City. The project, completed over three years, presented many challenges with scheduling. Work on the dam and bridge deck had to be coordinated with high and low river flows, changing reservoir levels, and environmentally sensitive periods on the Elbow River. The consultants helped the City balance the need for dam rehabilitation with the risk of flood or drought occurring while the dam was non-operational. They also provided guidance to the contractors regarding the timing of various portions of the work. The project was completed for the agreed budget, which was a portion of the overall $81 million budget of the larger Glenmore Dam Infrastructure Improvement Program.
Glenmore Dam is classified as an Extreme Consequence dam in accordance with the Canadian Dam Association Dam Safety Guidelines (CDA 2007); therefore, ensuring the safe operability and stability of the dam provides a safeguard to possible extreme economic, environmental, and human life losses.
There was little as-built information available for the almost 100-year-old Glenmore Dam; this challenge was overcome through a good working relationship between the City, the engineers, and the project’s prime contractor.
The consulting firm used a 3D finite element dynamic analysis for seismic modelling of the dam, an advanced modeling technique more commonly used in high-seismic areas and not usually applied to dams in the region.
The project involved the design and provision of the following manufactured parts:
• 21 steel spillway gates, including embedded parts.
• 21 electric-powered, wire rope hoists for operating the spillway gates.
• Architectural precast concrete balustrades and railings along the bridge deck and elevated spillway hoist platform, respectively.
• Lighting for the elevated spillway hoist platform and platform access house, the bridge deck, and along the arches supporting the bridge deck.
• Post-tensioned rock and pier anchors along the spillway section of the dam and load testing of existing rock anchors in the spillway stilling basin.
The project required new construction as follows:
• Replaced bridge deck, including rehabilitation of the supporting concrete piers and spandrel walls.
• Modification and extension of the concrete weir crest, main piers, and the addition of 14 intermediate piers.
• Raise of the screen house by adding a precast concrete parapet and roof and adding a precast concrete hoist platform access house.
• Replacement of deteriorated and damaged concrete along the upstream face of the dam and at other locations along the dam, including the spillway stilling basin.
The Glenmore dam began operations in 1933 as a means to supply drinking water to the citizens of Calgary. For almost 90 years, the dam and reservoir have provided a source of drinking water to a rapidly growing city. The dam and reservoir are also the only method to mitigate high inflow events within the Elbow River and prevent flooding downstream. In addition to their utilitarian functions, the dam and reservoir are sources of recreation, including boating — the replica paddle wheeler S.S. Moyie operates on the reservoir from a dock at Heritage Park — walking and running, as the bridge deck on top of the dam links the city’s 27 km pathway system around the reservoir and along the scenic Elbow River. The dam site was first surveyed in 1930 and was the largest public works project ever undertaken in Calgary. The same year, a City committee named the project Glenmore, a Gaelic word meaning big valley. During the Great Depression, the project was an important source of local employment. In 1931, the City started construction of the water purification plant (the Glenmore Water Treatment Plant), an Art Deco-style building of brick, stone, and marble. By 1933, the dam was fully operational, and the system dubbed one of the most modern waterworks systems on the continent. In 1992, the plant was named an American Waterworks Association landmark. Glenmore Dam is classified as an Extreme Consequence dam in accordance with the Canadian Dam Association Dam Safety Guidelines (CDA 2007).
