By Jane Mosgrove
A tunnel is being designed to run under Somerset Street that will reduce overflow from sewers into the Ottawa and Rideau rivers by 90 per cent.
Sewers in the downtown core are combined, meaning both storm water and sanitation goes through the same system. The spring thaw or heavy storms can add considerably more water to the system causing it to overflow into the rivers. The tunnel, which is being funded by the region and the city, would serve as a temporary holding area for the excess sewage.
The problem of sewage overflow is fairly common says Stephanie MacFadyen of the Canadian Water and Wastewater Association.
“There’s still a number of older cities that have combined sewer systems and have to deal with overflow when the wet seasons arrive,” she says.
Somerset Regional Coun. Diane Holmes says she is pleased with the tunnel proposal because overflow has been a problem since sewers were put in.
“Finally we’re taking our responsibility (to the environment) seriously,” Holmes says.
But she says people have typically asked for money for parks and sidewalks.
“Cities haven’t been spending money where it hasn’t been asked for,” Holmes says, “and sewers just aren’t very sexy.”
Holmes adds the lack of money from the federal government, and no strong local environmental group as reasons why the storage tunnel is just now being designed.
The tunnel being planned for Ottawa will allow excess sewage and storm run-off to be directed into it. The sewage in the tunnel will continue through the system and on to the water treatment plant.
The wastewater storage tunnel will be about 4.5 kilometres long and about 50 to 60 metres below Somerset Street, from Strathcona Park in Sandy Hill to the railway tracks west of Preston Street. The tunnel is estimated to cost $45 million, with the city paying $29 million and the region funding the rest.
One of the main aspects of the design phase will include examining the rocky area the tunnel will go through. To do this, the city will bore into the rock around April after informing Somerset residents, says Noel Finn, the city’s senior project engineer. Residents along Somerset Street shouldn’t experience much disruption from the test drilling, he adds.
The design phase of the wastewater tunnel is expected to take until the summer of 2002 when construction is expected to begin. Creating the tunnel is slated to take three to four years.
“We want to make sure we do the job right so we’re going to take a long hard look at what we’re doing,” says Finn.