This page provides some information to assist you with information to help you protect your Home or Cottage. Before reading, remember we’re volunteers here, and not experts(see Disclaimer section of website):

NOTE: Sandbag Dikes were ineffective against the May 31st storm. Other alternatives such as stone walls might be more appropriate for future storms.

How do I build a Sandbag Dike:

Click on this link below to find out how to build a Sandbag Dike:
http://www.gov.mb.ca/emo/home/prepare/sandbag.html

 

How do I build a stone wall?

Stone wall construction requires heavy equipment and engineering. It is recommended that the services of a contractor be engaged to construct a stone wall.

How High Do I need to be?
That is the million dollar question. There seem to be four factors to consider:

1. Estimated Water Flood Level;
2. Estimated Wind Set-up(often called Wind Tide);
3. Estimated Wave Height;
4. Some type of a safety factor.

This website is not an authority on these items, however, the following links may help you in determining your own idea on what height you need to be at:

• Estimated Water Flood Level – Manitoba Water Stewardship’s June 30th Flood report states 817.8 is the current worst case forecast. For the most current report go to: http://www.gov.mb.ca/waterstewardship/floodinfo/forecasts_reports.html#daily_flood_reports
• Estimated Wind Set-up(often called Wind Tide) – Manitoba Water Stewardship has provided an estimate of Wind Set-up for what a sustained North Wind of 60 km/h would do to Lake level including Wind Set-upthe South Basin(Note: This is basically what we at the beach often call Wind Tide). Basically a 3 foot Wind Set-up(Wind Tide).Here is where this information is located: http://www.gov.mb.ca/waterstewardship/floodinfo/forecast_centre/maps/inundation_maps/rm_portagelaprairie.pdf
• Estimated Wave Height – In the May 18th Flood report, Manitoba Water Stewardship reported:During high winds, individual properties and dikes will be impacted by wave action differently. There are a number of factors that will change the way wind and the resulting wave action impacts properties and dikes, including: the slope of the shore, the distance from the water, obstructions that may buffer waves (roads, vegetation, etc.), the slope and height of flood protection dikes, and the depth of standing water against the dike.
  • Waves will generally be higher and have more energy if the beach is shorter and has a greater slope. Waves will generally be lower and have less energy if homes are located far from the normal lake edge, have a gently sloping beach or are travelling over flooded vegetation or other obstructions. Homes with a gently sloping beach could experience waves as high as 3 ft.
  • The impact of waves on dikes is dependent on the depth of standing water against the dike and the slope of the dike. With a sustained 60 km/hr offshore wind:
  o Sandbag dikes close to the water’s edge may experience waves as high as 3 ft
  o Sandbag dikes with water reaching the base of dike may experience waves as high as 4 ft
  o Sandbag dikes with water reaching part way up the dike are likely to experience waves as high as 7 ft.
  o Clay dikes are generally built with a gentler (5:1) slope when compared to the slope of sandbag dikes (1:2), dissipating the energy of the wave and reducing wave height.
  • Wave action is not illustrated on the inundation maps due to the site-specific circumstances of each property.
  
• Some type of a safety factor. Manitoba’s Sandbag Dike brochure suggests a 2 foot of freeboard.

So an example of how all this works, assuming:

• Lake Level of 817.5 feet
• Wind Set-up of 3 feet
• Wave height of 3 feet
• Freeboard of 2 feet
  817.8 + 3 + 3 + 2 = 825.8 feet is height sought

Now, for this example, if you’re elevation is:

• Above  825.8, you would be OK
• Below 825.8, you might want to consider increasing “height” through a Dike. For example, if I am at 820, I would build a Dike of 5.8 feet, and I would then be at 825.8

Elevations
Owners are encouraged to post any Elevations they might know below as “comments” so others may have an idea. PLEASE NOTE TO ALL: This information is being provided without any guarantee or warranty.