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Dike Questions

Who owns the dikes throughout the Valley?

Different dike infrastructure in the Town of Drumheller is owned by the Town and the Provincial Government. There are currently over 30 km of diking or infrastructure acting as a dike in the Valley.

The dikes will be maintained by the Town, as directed by the Province. 

What are these dike condition inspections that are happening, and why are they important?

In September 2020, engineering consultants and field crews began clearing and mowing vegetation on the top and sides of dikes along the valley. The crews inspected a total of 6.5 km of Provincial dikes in various locations.

This inspection program looked at Provincially-owned dikes to assess the health and condition that they’re in. The Drumheller Resiliency and Flood Mitigation Office has been working with local contractors and engineering consultants to plan and execute inspection work during the project.

A condition inspection of Provincial dikes is being conducted to determine if maintenance and repairs are required. This also allows us to evaluate the condition and assists in determining what our new design will include.

Where are the dike condition inspections taking place?

Work is scheduled for the following areas:

  • Dike B (River Grove Campground and Cabins)
  • Dike C (Drumheller North by Travelodge Hotel)
  • Dike D (Badlands Community Facility to Riverside Drive East)
  • Newcastle Dike
  • Midland Dike
  • East Coulee Dike

How long will the dike condition inspections take place?

Inspections began on September 17th, and work is expected to be completed by the end of October. Crews are planning to be working weekdays 8 AM-6 PM to minimize disturbance and disruption.

Will the dikes change?

Current diking will be wider and higher. There will be new diking in some neighbourhoods that currently have no protection, where structural measures are viable. The land on top of the dikes and in the river's conveyance area will largely become public spaces and haul routes during emergency response to floods.

What will be the elevation of the dikes?

The dikes will be 6m wide and, on average, are 1.5m high. The elevation will differ throughout the valley because of the slope of the river. They need to be wide enough to become haul routes and allow equipment to drive on top should the dike need to be elevated beyond this height during a flood event. The dikes will be built to withstand a minimum flow of 1850 cubic metres per second (m3/s) plus 0.75m freeboard. Two of the most significant floods in the valley were the 1915 flood with a flow of 2000 m3/s and the 2005 flood with a flow of 1450 m3/s.

What will the width of the footprint area need to be to obtain a 6m top?

The footprint area will vary based on the location and ground elevation where the berms will be constructed. One of the purposes for gaining entry permission to private properties is to further define these designs.

When does construction of the dikes start?

Final engineering designs are still being developed for berms. Spring 2022 is the new target for construction as we must include new provincial maps in our designs.

How will the rain water get to the river if there is a dike?

The existing stormwater channels will have pipes with backflow devices installed where they intersect the new dikes and enter the river. This is a common practice and typical back flow devices can be seen at 12th St West in Newcastle and 25th St NW in Midland. All new dikes will be designed with stormwater systems that allow rainfall to flow back into the river to mitigate ponding on the dry/land side of the dike.

When will the dike alignments be released?

Engineering consultants have developed draft dike alignments that identified several properties that the dike will directly impact. The flood office has asked the engineers to review their plans to find solutions that will minimize the impact on private property compared to their first draft. Once these have been revised, Scott Land & Lease will be meeting directly with impacted landowners to review the dike alignments.  It is important we respect directly impacted landowners and inform them personally of the impacts to their property before the alignments are made public.

As the current dikes in Drumheller do not meet the design flood elevation of 1850 m3/s plus 0.75 m freeboard, if someone intends to take out a development permit do they have to build the main floor to 1850 m3/s plus 0.75 m freeboard?

Residents located within the flood hazard overlay in the Land Use Bylaw must construct the first floor of their houses to the flood construction level which is the water elevation of an 1850 m3/s flow rate on the Red Deer River. Residents are not required to include a freeboard, however, building above the flood construction level increases their resilience to future flood events. The flood construction level for protected areas will be re-evaluated in the Land Use Bylaws once the dikes are built.  

If the Town runs out of dollars building to 1850 m3/s plus 0.75 m freeboard and there are remaining dikes yet to construct, how will the Town be protected from possible high-water events?

There is no expectation that we will run out of money for the dikes that have been funded. The province of Alberta has recommended that the Drumheller Valley build flood mitigation up to the 1850 m3/s Red Deer River flow rate. If Drumheller only built the dikes to the 1640 m3/s level, we would not be in accordance with that requirement and could impact future provincial funding.

Can the Town address the conflicting information in the Municipal Development Plan with regards to building dikes to 1640 m3/s plus 0.75 freeboard and 1850 m3/s plus 0.75 m freeboard?

The current Municipal Development Plan, issued in December 2020, refers to the new Provincial 100-year regulatory design flow rate of 1850m3/s. Of the 23 times the design flow rate is mentioned, there are 2 occurrences where the old, outdated flow rate inadvertently did not get updated.  The Town is aware of this and plans to update the MDP for this and a few other typographical errors in spring 2022.

Click here to view the current Municipal Development Plan 

For detailed information on the MDP and LUB, contact Drumheller’s Development Office at development@Drumheller.ca

Where is the dike material coming from if hill dirt is not being used? Is it true the Town is using bedrock to construct the dikes as conveyed by the previous flood mitigation officer, Mark Steffler?

ParklandGEO Geotechnical Engineering is currently assessing source material.

When the dikes are built in various neighborhoods, is it the Town's intention to have a drainage ditch between the properties and dikes so that there is system in place for heavy rains and protection of the houses?

Yes. The dike designs will include design of overland conveyance route along the inside toe of the dikes.

When the dikes are being constructed and heavy compaction is carried out, who will be covering the damages to house foundations and cracked wallboard that may occur?

There will be provisions in the contract documents requiring contractors to undertake the work in a manner to mitigate impacts to adjacent structures in their use of heavy equipment.

Will there be new pathways constructed on the dikes?

The current strategy is to maintain pathways on dikes where they are existing (i.e. – Downtown Dike, Midland and the existing portion of East Coulee), but there are not plans to build new pathways with the dike construction work. 

Will the new dikes planned for downstream of my community increase my flood risk?

Typically the expected water level increase upstream of a dike is in the range of 1 – 5 cm for the design flood event, and this water level change will taper to zero impact a couple of hundred meters upstream of the dike, so we do not anticipate changes to the level of flood risk for upstream communities.  The water level change specific to each project area will be verified by the Flood Office’s hydraulic modelling specialist team, and any impacts noted to be significant will be mitigated.  This information will also be shared with Alberta Environment as part of the Water Act regulatory review process.