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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.
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