Sandbags can be useful in many applications, but they are a particularly good option for creating a barrier to hold back flowing water. Sand, silt and clay are all filler options, but sand is the easiest to work with. When stacked properly, a sandbag barrier can prevent expensive damage to your land and important structures. Though the installation is labor-intensive, with several helpers and a large supply of sandbags you can construct a temporary barrier fairly quickly that can later be easily dismantled.
Things You'll Need
- Sand, silt or clay fill
- 6-mil polyethelene plastic sheeting
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Calculate the height for your barrier; it should be at least 1 foot taller than the expected final water height.
Calculate the width for your barrier; it should be at least twice as wide as it is tall.
Choose a location for the barrier which provides a good bond between the barrier and the ground. Remove anything, such as branches and rocks, that interferes with this bond before beginning construction.
Position the bottom layer of sandbags lengthwise and parallel to the flow of water. Overlap the filled portion of each new sandbag onto the unfilled end of the previous sandbag. Position the tied end of each sandbag facing downstream. Position subsequent rows so that the joints of the previous rows are aligned with the centers of the bags in the next row.
Walk over each layer of sandbags to compact the fill, strengthening and stabilizing the barrier while creating tight seals between the joints and layers.
Stack the sandbags in a pyramid shape if the barrier is more than 1 foot high to help stabilize the barrier against the force of flowing water.
Position clusters of sandbags every 5 feet along the length of the barrier to aid in stabilizing it against the force of flowing water.
Spread a 1-inch-deep, 1-foot-wide layer of fill along the bottom layer of the barrier on the water side, using a shovel.
Lay plastic sheeting loosely over the top of the barrier, extending it down over the side facing the water and 1 foot beyond the bottom edge onto the layer of fill. Overlap additional plastic sheets by at least 3 feet, working downstream, with overlaps facing upstream to prevent water from flowing under the plastic and causing damage.
Place a row of sandbags on the end of the sheeting to hold it down where it lies on the fill along the water side of the barrier. Place a horizontal row of sandbags on the sheeting along the top of the barrier to hold it in place.