Keeping the worksite open (c) Dominion Divers

It was a beautiful January in Brandon, MB. Clear blue skies, –35°Celsius in the morning, warming up to –22° Celsius by mid afternoon. Dominion Divers cut and jack hammered their way through seventy-five cm of clear blue ice on the Assiniboine river. An area ten meters by twenty-four meters (that’s 180 cubic meters!) had to be opened and kept open for the duration of the project. The area had to be large enough to float their 6,800-kg capacity mobile lifting structure, and manoeuvre all the screen structure / fish exclusion system components.

Dominion Divers started by giving the forty-six-year-old existing structure a new home - in the local landfill. Next, they craned the 41 cubic meter concrete form over the pump house and into the river, and used a lifting structure to place it with pinpoint accuracy. An ice barricade was bolted to the form, and to provide a stable base for the new intake structure / fish exclusion system, it was tremied with concrete.

Dominion Divers then craned the new 5,900-kg screen structure / fish exclusion system into the river and placee it without damaging any of the mounting hardware. Finally all the in-water piping was installed and covered it with dry mix concrete in geo-textile bags and added a layer of granite riprap for added protection.

Dominion Divers took only six weeks to complete the $350,000 project for Manitoba Hydro, accumulating a total bottom time of one hundred and fifty hours, with only ten hours of lost generation. Do it fast – but do it right!