Councillors tout tanks to stop Glen Cairn f looding
See holding tanks similar to those installed in Alta Vista as way to shut off sewer spills
Building huge underground holding tanks to handle stormwater or sewage in emergencies may be one solution to flooding in the Kanata area, according to some councillors.
They say the tanks, which are used in other parts of the city to prevent flooding, could be placed in neighbourhoods such as Glen Cairn, the hardest hit community in the flood of July 24-25 this year.
The storm brought so much rain that it got into the sanitary sewer system and sent sewage into basements, especially in certain low-lying neighbourhoods that flooded for the third time since 1996. One of the city’s biggest wastewater pumping stations, Acres Road, also overflowed during the July deluge.
The need for storage is especially pressing in Glen Cairn, where the problem of low-lying basements was raised to the former Ottawa regional government 10 years ago in a report on the Hazeldean pumping station.
That report found there were basements in Glen Cairn as low as 94.5 metres above sea level. But the Hazeldean station, which serves Glen Cairn, has an emergency overflow at 95.2 metres. Therefore, basements could flood before the emergency overflow at the pumping station kicks in.
As well, the Glen Cairn basements are too low to drain by gravity to the Carp River during a big storm.
Kanata South Councillor Peggy Feltmate, whose ward was hardest hit by July’s storm, says storage under a park in Glen Cairn may be a big part of the flood remedy.
She visited a completed storage facility in Sandy Hill on Friday and said she found it “impressive.”
Sandy Hill was one of a number of Ottawa neighbourhoods hit by repeated incidents of flooding. The city built a storage tank under Sandy Hill Park to handle stormwater and sewage. The park elevation was also lowered so it can act as a stormwater pond during big storms.
Feltmate said she isn’t certain that the park in Glen Cairn is at the right elevation to be holding stormwater, but she wants to pursue it.
Peter Hume, chairman of the planning and environment committee, noted that a sewage storage tank was placed in his Alta Vista ward in 1999 to help prevent sewage backup. Hume said flood-prevention projects in the west end should be under way next year. Minor measures to improve water flow at culverts and ditches dur- ing storms have already begun.
The city spent $22 million in 2006 to reduce basement flooding, then something similar over the following two years. Hume says councillors are highly sympathetic to the need for flood-remediation measures and “the decision-making process will be quick.” He says the city will shift spending if necessary to get the work going.
Stittsville-Kanata West Councillor Shad Qadri said it makes sense to use underground storage tanks in communities that are already built. And he said it makes more sense in new communities to make sure at-grade stormwater ponds have the capacity to handle the precipitation from big storms.
Qadri said Ottawa’s wastewater treatment system all drains to a single plant and it’s wise to build some storage capacity to give that system some breathing room.