Replacement of raw water intakes
Replacement of raw water intakes
2023
gbi was mandated to provide engineering services for the replacement of two raw water pipelines, which were partially nested inside one another at the bottom of Lake Memphremagog, for the municipality of Canton de Potton and the Owl’s Head ski resort, a project far from ordinary.
The ski resort and the municipality each wanted their own separate water intake: an opportunity to revitalize the city’s water supply infrastructure while planning for increased flow capacity in the future.
Additionally, it was necessary to consider that the ski resort had pre-purchased European-model snowmaking equipment. gbi’s engineers integrated this equipment into the system. The ski resort aimed to increase flow and have colder water to produce snow more efficiently and for a longer duration.
An Environmental Complexity
Environmental protection was considered from start to finish throughout the entire project implementation.
During the project, we mapped the lakebed to position our anchors precisely and avoid surprises during excavation phases. Environmental aspects were respected by the teams during sensitive works in Lake Memphremagog, and mitigation measures were planned in advance and detailed in the plans and specifications.
These mitigation measures were implemented by our teams to minimize the noise and vibration impacts caused by blasting and hammering. Indeed, an air curtain (a perforated flexible hose with an air compressor placed at the bottom of the lake that reduces the speed of sound wave dispersion and shockwave impact) was also installed during hammering work to avoid disturbing fish and marine wildlife.
An Unusual Anchoring
Given the depth of the lake and the very steep slope, the anchoring of the Mont Owl’s Head pipeline had to be secured to the underwater rock face rather than being laid on the lakebed, as is the standard practice. The project required considering factors such as depth, rock and cliff types, and screw lengths to ensure the anchors’ solidity.
To drill into the rock, several techniques were used, including underwater blasting and long hammer drilling on the stone jetty in the lake. Additionally, since the pumping station is located at a depth of 9 meters, the intake anchoring had to be designed for over 18 meters of water depth.
A Solution for Collective Needs
For the residents and all water users of the Canton of Potton, this new connection will provide better raw water quality and secure the water source. The proposed solution was designed with future needs in mind. The municipality will be able to increase its capacity if desired.
Durability of Installations
Finally, regarding infrastructure maintenance, durable materials were selected. An access point for equipment cleaning was also incorporated. The new pumping station at the ski resort is equipped with a ceiling hatch allowing pumps to be removed for inspection and cleaning. This feature also enables monitoring of the possible invasion of an invasive species in the lake: the zebra mussel. Thanks to this new design, this dangerous mollusk will now be under close watch.
A Standout Project
The raw water intake replacement project was a finalist at the 2023 Quebec Consulting Engineering Grand Prizes in the Urban Infrastructure category, awarded by the Association of Quebec Consulting Engineering Firms.
