Community Information Session in Bowness reveals new details

January 19, 2018 by CRC Action Group in News

On Tuesday evening, the City hosted a Community Information Session in Bowness so that residents could learn about flood mitigation plans slated for the community, namely a local berm planned for Bow Crescent. We were in attendance and it was a packed house.

Information about the proposed berm was distributed via a six-page handout in resident mailboxes in December, however, we wanted to update you on information gathered at the info session on what’s proposed:

The average height of the berm will be 1 meter, which includes 0.5 meters extra safety factor. Ranges from less than 0.5 meters to 2.2 meters in heightdepending on the property.
For some properties, given the varied topography, a wall as opposed to berm may be built to required height specifications.
The berm will be at the correct height to mitigate an approx. 1230 cms* flood (being a 1 in 20 year event). The 2013 flood on the Bow was approx. 1840 cms and Bowness will see some overland flooding at 850 cms (12% chance each year).
The five-year deal with TransAlta to modify operations of the Ghost Reservoir will add additional mitigation to reduce (with the berm) the risk of flooding.
The City will pursue large upstream reservoir mitigation built by the Province in order to achieve at a minimum a 1:100 target of 2020 cms attenuation. The goal is to reduce flood risk to less than 0.5% a year.
The specific design and location of the berms is TBD. Typical berms are 4:1 (i.e. 4m wide for each 1 meter high), but it is unclear if these specs will apply to this project.
Requires 1 meter width of clay to make it impervious.
Lots of consultation to come.
Construction in 2020. Full timeline pictured below.

*Cubic Meters per Second