Hydro Station Modifications
Dominion Divers Ltd. performed demanding underwater work for the installation of a new generating unit at Winnipeg Hydro’s Pointe du Bois generating station, the oldest hydroelectric station in Manitoba.
Downstream piers with stop log gains were added to the powerhouse structure at Unit #1 to allow the draft tube to be de-watered.
The project required precision surveying, form placement, placing explosive charges, airlifting rock blast debris together with placement and reinforcement of underwater concrete.
More than 100 cubic metres of bedrock was blasted and removed, in the wet, from the downstream area of the station’s draft tubes.
Special challenges included the proximity of the work to the station’s powerhouse. In addition, there was a concern that fish kills should be kept to a minimum.
The Dominion crew constructed a level, 7 by 10 metre structural concrete slab, 0.1 to 0.5 metres thick. This was accomplished by using an anti-wash admixture to facilitate placing and levelling underwater.
The forms for the new piers were subsequently positioned,anchored, and tremied.