Fill bags approximately ½ full. Bags do not need to be tied. Lay flat with the flap folded under the bag. Overfilling the bags leaves gaps.
Using a shovel with a pointed end makes filling the bags easier.
For stability, sandbag dikes should be kept as short and low as possible.
A sandbag dike width should be 3 times the height.
Tamp down the bags after placing them to make them as flat as possible.
Overlap the bags lengthwise and parallel to the water flow. Stagger and stair-step the filled sandbags to eliminate gaps. (Similar to bricklaying)
A completed dike can be sealed with 6 ply poly (plastic) sheeting. Place poly a few feet from the bottom of the dike and go up and over the filled bags on the water side. Anchor the plastic on the bottom and top with a row of overlapped filled sandbags.
When the water has receded, bags and plastic should be removed. Sunlight will disintegrate the bags over time.
Any bags that have come in contact with flood waters are considered contaminated. The sand cannot be used in sandboxes, playgrounds or any place where it will come in contact with humans.
Contaminated sand can be returned to where you got it, used as fill for driveways and roadways. Check with your local landfill on the possibility of disposing of the filled, used bags there.