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Revisiting Cofferdams versus Sandbags

A sandbag flood wallSandbags as Water Barriers

Sandbags were once the go-to for flood protection and water barriers, but in recent years, more and more studies have found this method to be a dangerous and out-dated one. We’ve noted this in a previous article but below is a more exhaustive in-depth list of the various concerns that come along with the use of sandbags for preventing floodwaters from reaching your home.

It takes 2 people to properly fill a sandbag for use. On average, one hour of work yields only a dozen or so bags. It is recommended that you have multiple changes of sandbags for any emergency situation, as they have to be rotated out regularly. Each sandbag weighs approximately 30lbs when filled. This makes using sandbags both highly labor intensive and time consuming.

The material used for the bag itself is either treated burlap or a woven polypropylene. Burlap has been known to begin to rot with time, particularly after absorption of moisture, and once the bag has begun to deteriorate, the integrity of the sands ability to absorb will be compromised. When using a polypropylene bag, a sturdier and more dependable material, UV ray exposure can weaken and break down the material, again compromising the integrity of the sandbags overall function. As far as the fill goes, it requires dry sandy soil with no gravel-fill that absorbs well. More often than not, it’s nowhere to be found on-site. For these reasons, the material comprising the sandbag is unsound.

Now let’s talk about the sandbags limits while in-use. Sandbags are ideally used for low-flow protection only, meaning under two-feet of water. Anything above that indicates requirement for the use of another form of protection/prevention. In addition, the bags must be stacked in a particular way, requiring the creation of a trench, in order to provide the best possible results.

After the threat of flooding has passed, the arduous task of dismounting the bags begins, requiring additional heavy labor. During the deconstruction of the bags formation, clay from inside the bags has been known to leak out, along with the water. The water absorbed during the flooding process has been found to carry traces of sewage, waste, bacteria, and hazardous contaminants and pollutants that cause illness in humans and animals if we come into contact with it. For this reason, it is required that the bags and their contents be disposed of in a safe way by a hazmat team trained to handle bio-hazardous materials. Sticker value says “cheap alternative” but this route is ultimately extremely costly once all things are factored in.

The Environmental Agency has gone on record to state that sandbags are “relatively ineffective for flood protection when compared to purpose-made designs of flood protection” and that they “do not properly seal out water” and they continue by saying that they “strongly encourage people to use purpose-made flood protection measures” like the water inflated dams offered here at Dam-It Dams.

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