The Drumheller Resiliency and Flood Mitigation Program began a series of community engagements to discuss community-focused proposed flood protection measures in the Drumheller Valley, beginning with the Midland area on Thursday, November 18.
Each engagement has two components, a virtual Zoom meeting and an in-person meeting at the Badlands Community Facility (BCF) to give residents ample opportunity to participate in the events.
“The 100-year flood we’re designing (flood protection) to has seen a 30 per cent increase in the last 30 years,” Flood Project Director Deighen Blakely shared during the virtual meeting on Thursday. “The target has been going upwards and we need a resilient design for the future.”
Joining Ms. Blakely at the Zoom engagement were Drumheller Chief Administrative Officer (CAO) Darryl Drohomerski, Kathryn Kolaczek with Alchemy Communications, geotechnical engineer Mark Brotherton with Parkland Geo, professional engineer Robert Cheetum with Klohn Crippen Berger, landscape architect Ernie Webster with IBI Group, and Community Advisory Committee representative Irv Gerling.
Some 35 members of the public were in attendance at the Zoom meeting on Thursday, and an additional 45 people were registered for the in-person meeting that same evening.
Ms. Blakely shared there will be over 14 kilometres of dikes to be built over the next several years, and the tendering process for some of these projects is expected to begin over the winter; construction is anticipated to begin in spring 2022.
During the presentation, Mr. Brotherton explained the proposed berm designs will protect flood areas from overland flooding during flood events; however, they will not be designed to protect against seepage.
“Typical seepage protection is a physical cutoff,” Brotherton explained.
He noted these barriers would need to “circle the entire floodway area” and, to protect an area like Nacmine or Midland, would require approximately one kilometre of protection; at some $10,000 per linear metre, this would be a hefty price tag which would use a significant portion of the $55 million in provincial, federal, and municipal funding.
A barrier would also pose another problem by preventing draining of groundwater due to seasonal fluctuations, and pose additional flooding concerns. Mr. Brotherton stated the best protection against seepage is to use proper yard grading, weeping tiles, and other preventative measures at the home level.
Mr. Cheetum showed slides of how the proposed system will tie in to the existing flood wall in Midland along North River Drive, and how the proposed system will protect the area in the event of two different flood events; in a flood event with a flow rate of 1,850 cubic metres per second (cm/s), the flow rate approved by the province for the project, approximately 190 homes in the area will be protected by the proposed dike system.
In an unprecedented flood event with flow rates of 3,000 cm/s, the system would provide protection to an additional 35 homes and one multi-unit building.
Another topic which has been of interest to the community is trees and trails along proposed flood pathways. Landscape architect Ernie Webster explained a proposed landscape masterplan is being developed, including a tree strategy plan.
Each tree in the area has been assessed for health, condition, and species, and Mr. Webster explained through this inventory they will have a better understanding of any potential impacts on wildlife and bird nesting. Although some trees will need to be removed, Mr. Webster stated this is often for the better as many of the trees planned for removal are in poor condition and will be replaced by trees in better condition in the future.
Trees will not necessarily be replanted in the same location they were removed to avoid potentially compromising the dike system, and they are being mindful of future carbon sequestration.
Mr. Webster shared, when it comes to planning trails they are “trying to be mindful” of not to impact residents’ privacy and will tie new trails in with the existing network throughout the community.
The floor was opened for a question-and-answer period following the presentation. Questions were received both ahead of the engagement and live from attendees.
CAO Drohomerski was available to answer questions pertaining to the Town of Drumheller’s Land Use Bylaw and Municipal Development Plan.
Further engagement events are planned for Newcastle on Wednesday, December 1, and Dike D on Thursday, December 9 and will follow the same virtual and in-person format as the Midland meeting.
Those interested in attending the in-person meeting will need to provide proof of vaccination, medical exemption, or a private negative COVID-19 test result.
Masking is mandatory.