FARGO, N.D. -- If river levels rise as predicted this spring, some people likely will be building dikes.
“However, a dike will fail if not built correctly, so knowing the proper procedures for placing sandbags is very important,” North Dakota State University Extension Service agricultural engineer Ken Hellevang says. “Put a high priority on planning and organization and identify a supervisor for the project.”
Bags are made from different materials. Woven polypropylene bags are the most commonly used type in this area.
The bags usually are about 14 inches wide and 24 to 26 inches long. Other sizes also are available, but the bag is easier to handle if it’s limited to 35 or 40 pounds with filling material in it.
Sand is the easiest material for filling and shaping sandbags. Silt and clay in bags will form a good dike, but working with those materials is more difficult.
Hellevang has this advice for building a sandbag dike:
? Fill sandbags about one-half full.
? Do not tie bags closed. Untied bags form into the dike better.
? Lift bags using your legs to limit the strain on your back.
? Build the dike at least 1 foot higher than the projected crest level to allow for fluctuations in the water level.
? When selecting the dike’s location, take advantage of natural land features that keep the dike as short and low as possible. Avoid obstructions that would weaken the dike.
? Do not build the dike against a building wall because of the forces the dike may place on the building. Leave at least 8 feet to maneuver between the dike and buildings.
? Remove ice and snow from the ground before starting to build a dike or the dike will leak when the snow and ice melt.
? Since friction holds a dike from sliding, create a good bond between the ground and the dike. Remove anything that is slippery from the dike site. Do not put plastic sheeting under the bags since it will increase the potential for the dike to slide. If the dike is to be more than about 3 feet high, dig a bonding trench where the dike will be placed. The trench should be at least 4 to 6 inches deep and 18 to 24 inches wide.
? Use a sump or skimmer pump to remove water that permeates through the dike. Use ground fault circuit interrupters on circuits or extension cords to reduce the risk of electrocution.
For more details about dike building or other flood preparations, visit NDSU’s flood information Web site at www.ag.ndsu.edu/disaster/flood.html.
After the flood, do not use sand from bags exposed to floodwater for children’s sand boxes because floodwater generally is considered to be polluted, Hellevang says.
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http://www.ag.ndsu.edu/news/newsreleases/2009/march-12-2009/ndsu-offers-sandbagging-expertise
Contacts:
Ken Hellevang, (701) 231-7243, kenneth.hellevang@ndsu,edu
Ellen Crawford, (701) 231-5391, ellen.crawford@ndsu.edu
