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AE-626 (Revised) 0 Sandbag i for Flood Protection ig, Extension Engineer sandbag dike must be built properly to prevent or reduce flood damage. Managing Volunteers Since a dike will fail if not built correctly, training peo- ple on proper procedures for placing sandbags is very important. In the rush, volunteers will do something, but the result frequently is a dike that performs poorly or fails. Put a high priority on planning and organization. Identifying a supervisor for the project is recommended. W', Sandbags Bags are made from various materials, but the most common is woven polypropylene. They usually measure about 14 inches wide and 24 to 26 inches long. Other sizes of bags also are available, but bags are easier to handle if their weight with filling in them is limited to 35 to 40 pounds. 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. Fill sandbags slightly more than one-half full. Contact your county emergency management office for information on where to obtain sandbags. Site Selection When selecting the location for the dike, 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 due to the forces the dike may place on the building. Leave at least 8 feet to maneuver between the dike and buildings for observation, pumping seepage water and other activities. Since friction holds a dike from sliding, create a good bond between the ground and the dike. Remove ice and snow since it will melt permitting water to flow under the dike. Remove anything else that is "slippery." If the dike is to be more than about 3 feet high, dig a bonding trench where the dike will be placed if possible. The trench should be about 4 to 6 inches deep and 18 to 24 inches wide. Estimate Sandbags Needed Build the dike at least 1 foot higher than the projected crest level to allow for fluctuations in the water level. Local experience will assist in determining the amount of freeboard to provide. The U.S. Army Corps of Engineers recommends building a dike with a width at the base that is three times the dike height. For example, a 4-foot-high dike would have a base width of 12 feet. The corps indicates that each foot of finished dike length requires one bag, each foot of height requires three bags, and each 2.5 feet of width requires three bags. This results in each bag having placed dimensions of about 4 inches high by 10 inches wide by 14 inches long. 5ft 4ft NDSU aft 2ft Extension Service 1 ft North Dakota State University 7�� Fargo, North Dakota 58105 2' MARCH 2O10 _ _ _ - r Dimensions of a dike that is twice as wide as it is tall 4' - 6' - 8` - 1 0'