How Does a Sandbag Control Flooding?

Worth the Effort

Sand and small plastic bags have saved many homes, businesses and towns from disastrous flood waters. These small bags filled with sand by many volunteers are a critical tool when river waters start to rise. People in flood zones are very aware of the long, tedious hours necessary to fill the bags, tie them shut and stack them to ward off the water's devastation.

Filling the Bags

To construct a sandbag flood wall, you must have tons of sand, plastic bags to put the sand in and the cooperation of many volunteers. These bags are filled by hand using a small shovel or scoop. Some people or communities that have serious flood problems have devised bag-filling systems to make the task easier and to cut down on the manpower necessary to fill the bags.
Once the bags are filled and tied shut, the volunteers start the process of building the sandbag wall to hold back the floodwater. Some sandbagged flood walls are built on large sheets of PVC plastic, if there is enough time to construct them this way. The plastic also helps to hold back the water and keep it from seeping through the sandbags.

Constructing the Wall

The bags are laid down in alternating courses, just like laying a brick wall. Several rows are laid down for the base, or bottom layer, and then volunteers continue stacking the bags to raise the height of the wall. The bags are packed tightly to each other to avoid seepage.
This wall will divert the rushing water in another direction, or at least contain it within the newly constructed sandbag flood wall. The sand is very heavy, so it can withstand the amount of pressure that the rising water puts on it.
Even when the wall has been built, volunteers continue to keep an eye on the flood wall. Sudden onslaughts of rushing water can move and damage portions of the wall. Minor leaks and seepage can be patched with more sandbags in an attempt to save the wall, if they are noticed in time.

Keeping a Watchful Eye on the Wall

Many times, a large section of the sandbagged flood wall will breach, leaving the volunteers no choice but to evacuate the area and let the floodwater overtake whatever they had been trying to save. This can be a heartbreaking decision, especially after you have worked so long and hard to try to save the area.
When a call for sandbagging goes out, volunteers will come from miles away in an effort to help a struggling community. They will work around the clock, through rain or cold to build the wall. Success is met with cheering and relief. Those whose homes and businesses have been saved by sandbagging are usually the first to rush to another community to help.
Volunteering to help with a sandbagging operation means long hours and tedious work; it can also mean pride in holding back the raging floodwater and helping those in need.