Stack of sandbags
Sandbags can make defensive barriers in various situations. In combat, sandbags protect equipment and personnel from bullets and shrapnel. In civilian use, people frequently use sandbags to protect buildings, even whole towns, from floodwater. They fill bags made from canvas or synthetic material with sand and stack them to form a wall to keep the water at bay. Using the right technique to fill a sandbag is important, especially when you are in a race against time.
Filling a sandbag on your own can be awkward and time consuming. One hand must hold the bag open while the other shovels sand into the bag. Use a special funnel that has a wider tube than a regular oil or water funnel. Place it in the bag and shovel sand into the funnel. Lift the funnel upwards after each shovel of sand in readiness for the next. Leave enough material to tie the bag in a secure knot when it is filled.
The job is much easier with two people. One person needs to hold the bag open ready for the sand which the second person shovels. The open end of the bag should be rolled down by 2 inches to allow for tying. Take turns at doing each task. This helps to keep the filling rate high as one person does not become exhausted from doing all the shoveling.
In areas where flooding is a regular occurrence, the local authority may have access to a sandbagging machine. The filler holds the bag open, with the bottom of the bag on the floor, while sand automatically funnels into it from the machine. To speed up the process, drag the bag away once it is filled and then tie or staple it shut. This allows the next person to begin filling another sandbag immediately.
For a simple one-line barrier, lay bags end to end. Stagger the next layer to offset the vertical seams; this adds strength to the sandbag wall. For large scale deployment to protect against flooding, lay the bags in a pyramid shape. For a 1-foot high barrier, the base of the pyramid should be 2 1/2 feet wide with the bags laid side by side. A 4-foot high barrier with bags laid side by side will be 10 feet wide. To make a 100-foot long, 4-foot high sandbag defense wall, you will need 7,800 sandbags.