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National Guard Engineering Education. General Levee Information Levees are the most widely used method of flood control The most extensive levee systems.

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Presentation on theme: "National Guard Engineering Education. General Levee Information Levees are the most widely used method of flood control The most extensive levee systems."— Presentation transcript:

1 National Guard Engineering Education

2 General Levee Information Levees are the most widely used method of flood control The most extensive levee systems in the US are along the Mississippi and Sacramento rivers and their tributaries. The first levees were about 3 ft high but now they average 24 feet with some areas as high as 50 feet

3 Types of Primary Levees Earthen Levee: – Built out of soil or other natural material – Least expensive to build – Base must be large to provide the support required to withstand a heavy water surge – Not ideal in the absence of large amounts of land

4 I Wall Levee A vertical wall partially embedded in the levee crown, or the tapered top Not recommended when the soil is soft because the stability is reliant on the resistance from the soil For stability reasons, I walls rarely exceed 7 feet above the ground’s surface

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6 T wall levee Has a horizontal base that reinforces the soil underneath the levee, making it one of the stronger types of levees Requires piles be driven deeply into the ground This makes T walls expensive to build Typically used when walls higher than 7 feet are required

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8 Double Wall Levee Relatively new Consists of 2 metal sheet pilings and filler made with sand and concrete Most effective if there is a direct hit by a large item such as a barge because the filler will absorb some of the hit, preventing the levee from breaking

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10 Secondary Levees: Sandbags Made of burlap or other material that are filled with sand, soil or clay] Inexpensive, can be transported empty and filled with local sand In large flooding, water will seep through the bags and finer materials, such as clay, can leak out Only dry sandbags can be stored for future use – wet sandbags become contaminated Requires a lot of labor

11 Secondary Levees: Aqua Fences Plywood panels are unfolded and secured with aluminum poles and connected to one another with PVC Can be quickly and easily installed and dismantled and stored for future use Large initial purchase is required; cannot be used in an unexpected emergency situation unless already acquired Best for long-term emergency for areas of repeated flooding

12 Secondary Levees: HESCO barriers Collapsible wire mesh linked open top containers with a heavy-duty fabric liner, filled with sand, dirt or gravel Can be quickly and easily set up, harder for water to seep through because of thickness Must have room for the equipment required to fill the barriers; once in place, it cannot moved or stored for future use Fabric has a lifespan of 3-4 years

13 Secondary Levees: DefenCell Similar to HESCO barrier, but does not require the wire mesh Can be quickly and easily set up, easily transportable, can be carried by a person or pushed off vehicle with no risk of damage Harder for water to seep through because of thickness Once in place, it cannot be moved DefenCell

14 How many sandbags and tons of sand? Height RequiredNumber of Sandbags 1 foot8 2 Feet20 3 feet34

15 On average, sandbags are required to protect a single home that is being threatened by rising waters. To answer the following questions, use 425 as the number of sandbags required to protect a single home from rising waters. There are 65 homes in a threatened area. How many sandbags are required to protect these homes from rising waters? 65 homes x 425 bags per home = 27,625 bags

16 There are a group of buildings alongside a levee that is 15,840 ft. In order to protect these buildings from rising waters, determine the number of sandbags required to build a 2 ft. high secondary levee. 156,840 x 20 = 316,800

17 If 1 ton of sand can fill 50 sandbags, how many tons of sand are required to protect the single family homes and groups of buildings above from rising waters? 27,625(homes) + 316,800(buildings) = 344,425 bags 344,425/50 = tons of sand

18 Fargo flooding 2009


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