Train volunteers from your community so that they know proper procedures regarding how to place the sandbags and assign specific positions to each volunteer. This can help ease the process should your town be threatened by river flooding.
Monitor precipitation for a city closely, taking into consideration the amount of rain, snow accumulation and potential blockages in the river. If a river becomes blocked by ice, the accumulation of water can be too much for the river to move downstream.
Prepare sandbags, which normally consist of polypropylene and measure 14 inches wide and 24 to 26 inches long. Fill the bags with sand, silt, clay or dirt so that they are a half to three-quarters full.
Select a site for the levee and take advantage of natural features. Make sure that you leave about 8 feet to maneuver between the building of the dike and buildings to pump seepage or reinforce the dike as needed.
Estimate the number of sandbags that you need based on the linear feet of the levee. For instance, if the height of a levee must be 1 foot, you will need about 600 bags to complete a 100-foot-long section. If you have 2 feet, you will need 2,100 bags. Keep in mind that the pyramid-shaped levee should be at least 1 foot higher than the projected crest level of the river so that you account for fluctuations in water level.
Remove debris where the levee will be built.
Build a levee using the placement that would best benefit your situation. Place the sandbags lengthwise so they remain parallel to the direction of the flow and overlap the bag with the previous bag to create a tight seal. Walk on top of the bags to make sure that they are compact.