3 Ways To Defend Your Property From Rising Waters

In our last post, we discussed how it will take a fortress mentality to make properties more durable and resilient to extreme climate events. In this post, we’d like to explore the different options available to fortress a property from extreme flooding.

High Up & Far Away

Society discusses a property’s flood risk by whether that property sits in a flood zone or if it’s outside a flood zone. We think about this in a different way:

?? Every property is in a flood zone. The question is, which one? Some properties are highly prone to flooding, others less so. You can be on the top of the mountain, and still be vulnerable to flood if the soil around you is saturated enough.

With that said, distance is your friend. Distance from a flood source, the height distance of the ground elevation at your property, and the height at which your property is elevated off the ground. When you maximize all three, you can truly limit your exposure to flood damage.

Of course, once a property is built, you can no longer go back in time to adjust the distance. Properties are fixed at a location and for most properties, there is no physical way to elevate it. Because of that, we focus this article on flood defense. What are the prevention and mitigation options that can keep water away? We explore three main types of flood defense, Bags, Bladders and Walls.

Sandbags

Sandbags are usually the de facto tool to prevent flood waters from advancing. Fill burlap bags with sand, stack the bags on top of each other and you now have a sand wall that should be impenetrable to water. While relatively straightforward in theory, sandbags come with all sorts of issues complicate their effectiveness:

• You need to find an adequate amount of sand. Though we are surrounded by sand or dirt, you may have to dig a hole the size of a pond in order to get enough sand to stack.
• It is labor-intensive and time-consuming. It takes many, many shovels full of sand to perhaps complete the task. After that exhaustion, you then have to go stack them up and the typical sandbag is around 40 pounds!
• Once the flood waters recede, you must unstack them…more time and labor.
• And if you think you can just return the sand or dirt back where you found it, think again. Flood waters stir up a lot of much, debris and toxins. Sandbags are generally considered toxic post-event. They should not be re-used and they should be discarded in a locally approved sites.

Chemical Bags

An alternative to sandbags is chemical bags, which contain a water-absorbent material that swells when in contact with water, up to some maximum saturation, and then becomes a water membrane.

An example would be Quick Dam. Quick Dam can swell up to 12 inches in width, 24 inches long, and 3.5 inches in height. Here is an image:

The benefits of this technology are that:

• The bags are almost paper-thin and light. So it is easy to store vast quantities and have them mobile.
• After an event, the water within the sacks will evaporate and the sack will somewhat shrink to a lighter and smaller version of itself.
• They are relatively inexpensive.

The drawbacks to chemical bags are:

• Like sandbags, you may need hundreds or thousands to wrap a perimeter.
• As bags stack higher, they become less stable, so the height of your single-column wall is limited to 1-3 feet at max.
• Like sandbags, it is probably not prudent to reuse the sacks because of the toxicity of flood waters.

Other vendors in this space include

FloodAvert

Garrison Flood Control

Bladders

Bladder Flood Protection use water-filled vinyl/rubber tubes to block flood waters from advancing. Water at volume is dense and heavy. A water-filled rubber tube is heavy enough to prevent both, water from permeating beneath the tube and prevent water from bowling over the tube as well. They are often used in industrial use-cases, but can also be applied to residential. Here is an image of a flood bladder:

The advantages of flood bladders are that:

• They are reusable.
• They can be assembled in place pretty quickly.

The disadvantages are:

• They need to be filled with water. It could take many, many hours for the bladders to be flood ready.
• Since they are reusable they need to be stored. Depending on the length of tubing needed, a permanent storage area may be required, increasing the overall cost.
• Because of the density of water, the tubes want to flatten, thus limiting its height and the depth of water it can defend against.

Bladder solution providers include:

Aqua Barrier

Aqua Dam

US Flood (Tiger Dam)

Mobile Erected Walls

When the depth of water is expected to exceed 3 feet, the only other alternative is to erect a strong enough wall to hold the water back. There are now several manufacturers using various technologies to stop floods up to several feet in depth.

Muscle Wall - Muscle Walls are polyethelyne sections where pieces slide and lock into one another. Muscle Wall has several different options and do provide one option that can reach 8ft in height.

Muscle Wall example (4ft height)

Aqua Fence - Aqua Fence is the flip phone of flood defense. Their solutions come as a flip-style collapsible table. Once opened and assembled, the Aqua Fence capitalizes on the weight of water to lock the pieces in place and steel cable to prevent the open fence from hyperextending. The tallest solution stands at 9 feet.

PortaDam - Portadam manufactures steel A-frame walls for flood protection The company has an expertise in coffer dams, so they are well aware of how to keep deep flowing water away from life and property. They use the same technology for their flood solution.

The advantages of an erected wall are:

• Height. These solutions can provide protection to almost 10 feet.
• Strength. Erected walls are expected to withstand massive force loads from moving water.

The disadvantages of erected walls are:

• Cost. They are the most expensive option for obvious reasons.
• Storage. These solutions can not be neatly folded up and put away. A storage facility will be needed.
• Weight. They are heavy, because they need to be.

Which solution you use will depend on your own unique property situation. We recommend that you conduct a full flood risk analysis to understand the various depths of water you are likely to see, how frequently you may be exposed to flooding, and the budget available to execute a defense plan. If you’d like to explore the frequency and severity of flood events for your property, reach out to us at: [email protected]