Use of Sandbags
Q: What is a sandbag, and what are they used for?
A: Sandbags are sand or soil-filled sack made of burlap or polypropylene. These are used for purposes like flood control and military fortification. They can be used in building levees, berms, dikes and barricades for erosion control, floodwalls and traffic control as levees or dikes.
Q: When can they be used?
A: These sandbags are placed to divert the ways of floodwater. They are also used in preventing overtopping of streams with levees, and in training current flows to specific areas.
Sandbags alone cannot be used to keep all the water outside. With sandbags, you have to use baffle boards (plywood sheeting) or sheets of plastic tarp. In building a sandbag wall, you can place one another tightly together, forming the first layer of defence. Resembling the pattern of brick walls, second and subsequent layers can be placed.
Q: What are the different types of sandbags?
A: Burlap (untreated burlap sacks) is the most commonly used type of temporary sandbags, and they are available at feed or hardware stores. They tend to rot when exposed to the elements but can be used for many years when properly stored.
Woven polypropylene or commercial plastic is used when treated for UV exposure. They provide the most durable material for all temporary and permanent barriers and in flood control, levee, trench and berm construction. They aren’t biodegradable and will last for more extended periods when covered from the exposure of UV rays.
Q: What is the size that works best?
A: You can use bags about 14-18” wide and 30-36” deep. They should be half-filled for easy stacking and will weigh approximately 30 pounds. Thirty sandbags will weigh around half a ton and are the legal load limit for a half-ton truck.
Q: How many sandbags do I need?
A: It requires about 600 sandbags to cover a 100-foot section of 1 foot high.
Q: How much sand should be there inside?
A: Bags should be filled 1/3 to ½ of their capacity. This assures that the bag doesn’t get too heavy and that it seals well.
Q: What should I fill the sandbags with?
A: A heavy-bodied or sandy soil is more suitable for the task, but any useful material near the site can also be used. Coarse sand has the probability of leaking out through the weaves. Double bagging the material will prevent leaking. Gravel or soil is too porous, thus unsuitable for the filling process. Sandbags filled with earthly material will deteriorate soon.
Q: How many people do you require for the process?
A: Most people are capable of carrying a weight of around 30 pounds, but it will take mostly two persons to build a sandbag barrier.
Q: What is the best method?
A: It takes two people for the task. Both must be wearing gloves to protect their hands. One member must place the bag between the slightly set apart feet with hands extended. The throat of the bag must be folded to form a collar, enabling the other member to insert material with a shovel.
The person that holds the bag must stand with his legs slightly flexed, keeping the head and face far from the shovel. And the shoveler must insert the rounded shovel into the bag through the open throat. Any rush in this process will cause spillage and additional work.
Q: Tied or untied?
A: Untied sandbags are used in most cases. Tied sandbags are used in exceptional circumstances such as pre-filling and stockpiling, or filling holes and holding objects in position, or in forming barriers backed by supportive planks. They are generally easy to handle and store.
Q: What is the height limit in stacking sandbags?
A: This should be limited to three layers unless it is used as a backing or if they are placed in a pyramid.
Q: How do you stack sandbags?
A: Fold top of the sandbag and lay the filled part on top of the folded part.
- It is important to keep the folded part in the upstream or uphill direction to prevent them from opening.
- Fill each sandbag into place, completing each layer before starting the next layer.
Clear a path for debris to flow.
- Lay a plastic sheet in between the building and the bags.
Q: How do you discard the sandbags after use?
A: Homeowners first must remove the ingredients and then throw the bags away.
Sandbags exposed to contaminated floodwater require special handling.
- Sandbags should never be used to build a fortress around one’s property. This will cause additional damage if a flood comes.
- Garbage bags must not be used because they are too slick to stack and too large.