Frequently Asked Questions
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     AquaDam® cofferdams are a simple, effective, and environmentally-friendly water retention system. AquaDams® are ideal for:

  • Cofferdams

  • Stream Diversion

  • Flood Control

  • Bridge and Dam Construction or Removal

  • Lake and Pond Cleaning

  • Fish Habitat Protection and Restoration

  • Boat Ramp Construction

  • Pipe Line Crossing

  • Aquatic Pollution Containment

  • Erosion Control

  • Temporary Reservoirs

  • Portable Dam or Boat Dock

  • Dewatering Work Sites

In selecting a water retention system, several questions and concerns arise because of the many variables that must be considered. The following list contains many of the most common questions and concerns about dewatering work sites with AquaDams®.

What is the maximum length of an AquaDam®?

The longest continuous AquaDam® is 1,000 ft.

What is a closed-ended AquaDam®?

A closed-end AquaDam® with collar means one end is open which would have to be elevated, and the other end is closed with an attachment collar. Using the collar, a second AquaDam® can be attached making a watertight connection.

What is a double closed-ended AquaDam®?

Double closed-ended means that both ends are closed and fill hoses have been inserted into the fill tubes prior to closing off the ends. The fill tubes on one end extend up towards the top of the AquaDam®. Attachment collars can be put on one or both ends. This is a free standing unit that can be filled up on flat ground and does not require the elevation of either end.

What is a open-ended AquaDam® with baffles?

Open-ended with baffles means a baffle or skirt is sewed from top to bottom on the inside of the outside tube that forms the AquaDam®. A water tight tube is then inserted in each side of the baffle. A 3 ft. high AquaDam would have a baffle 3 ft. high separating the inside tubes. This will give the AquaDam® additional support.

When are open-ended AquaDams® used?

An open ended AquaDam® can be used crossing a canal or stream when the banks of the canal or stream are in an elevated position. The stream bank is what keeps the water from running out the ends of the AquaDam®. Open ended AquaDams® go bank to bank. AquaDams® with one end open and the other end closed with attachment collar go from open end elevated upon the bank to the closed end, determining where the AquaDam® will stop, such as half way across a river. Then a connection can be made.

What is a double closed-ended AquaDam® with hoses?

A double closed-ended AquaDam® with hoses means a combination of those above. Both ends closed, baffle down the middle, fill hoses already inserted to fill the AquaDam. It may or may not have attachment collars on one or both ends.

Do AquaDams® meet current laws and regulations as they apply to water retention systems?

AquaDams® are designed to meet EPA guidelines under Section 404 (40 CFR §230.1) as well as the Clean Water Act. The Clean Water Act and Section 404 guidelines prohibit discharges of dredge and fill material when a practicable alternative exists. AquaDams® provide a practicable alternative because they do not use any fill material and have no adverse effects on the aquatic ecosystem. The US Food and Drug Administration, after thoroughly testing the plastics that our product consists of, stated that it "is a material suitable to place in contact with food".

Are AquaDams® available for rental?

AquaDams® are available for rental at very reasonable rates. Our team of experts will install your AquaDams® and will remove them when the job is done.

How long can AquaDams® remain in place as a water retention system?

The outer woven geo-textile plastic tube standard to all AquaDams® contains UV inhibitors to prevent damage due to sunlight exposure. A properly maintained AquaDam® can remain in place for well over a year in direct sunlight. Stored properly, the shelf life of an AquaDam® is indefinite.

Limitations related to the flow periods

As long as the maximum water depth during the life of the project is accounted for, the AquaDam® will remain stable for the duration of the project. In the event of unexpected increases in water levels, most AquaDams® can be removed in one day without any damage to the environment and then reinstalled after the water levels return to normal. A second option would be to increase the height of the installed AquaDam® by pumping more water into the dam and temporarily over inflating it. For example, a 4 foot high AquaDam® could be over inflated to almost 8 feet in height under the right conditions.

Maximum depth of containment for dewatered work sites

The maximum recommended depths of containment for filled AquaDams® are as follows:

Standard Size (feet) Inflated Height
(inches)
Inflated Width
(inches)
Maximum Controlled Water Depth
(inches)
1 12 12 9
1.5 18 32 14
2 24 44 18
3 36 66 28
4 48 96 36
5 60 156 42
6 72 204 54
8 96 228 68
10 120 300 72

The maximum controlled water depth for any particular AquaDam® can be increased by backing it with a second AquaDam® or gravel, dirt, or sandbags. In most work sites, excavation of some kind will be taking place. The excavated material can be placed as backing for the AquaDams®, enabling them to handle greater water depths. The figures for maximum controlled water depth in the table above are based on free-standing AquaDams® with one side dewatered. By backing the AquaDams®  up with fill material or another AquaDam®, a greater water depth can be controlled than would be possible if the AquaDams®  were freestanding.

How does flow velocity affect the stability of an AquaDam®?

Flow velocity is a significant factor during the installation of the AquaDam®. As the flow is pinched off by the AquaDam®, the water velocity around the end will increase, and possibly erode the stream bed or bank. Stream bed erosion causes undercutting in the path of the AquaDam®, and the actual retained water depth may be greater than anticipated. Undercutting should be accounted for when selecting a particular AquaDam® size. Stream bank erosion could increase the width of the stream at the installation site and require a longer AquaDam® to span the stream. Since AquaDams® can be deployed quite quickly, any changes in retained water depth or stream width due to erosion are minimized.

Once an AquaDam® is installed in flowing water, the water will begin to pool in front of it and the flow near the AquaDam® will be minimal.

Are there any limitations on the bed width of the containment?

AquaDams® come in lengths of 50, 100, and 200 feet. Several standard AquaDams® can be joined with patented coupling collars to achieve virtually any length. Custom AquaDams® of any length can be made with sufficient notice. A small service charge may be applied to custom-length units.

Are there any limitations related to the slope of the stream bank or stream bed gradient?

If the slope is parallel to the length of the AquaDam®, it does not have an affect on the stability of the structure as long as the depth of the containment does not exceed the recommended values along that length.

The ideal installation site for an AquaDam® would be a smooth flat surface, but it will also provide a stable retention system on mild stream bed gradients. If the stream bed gradient becomes more extreme, backing the AquaDam® with gravel, dirt, or an additional AquaDam® will prevent sliding or rolling. If the only available installation site has a significant bed gradient, the best solution is to use a larger AquaDam® to provide additional head above the contained water.

How does erosion around the AquaDam® affect its usefulness?

An AquaDam® is flexible and conforms to the ground and surrounding area to provide an effective seal. Even if the ground is eroded away after installation, the AquaDam® will fill the gaps to maintain the seal.

The AquaDam® itself is not susceptible to erosion and does not use fill materials that can be washed out. By eliminating the use of fill materials, AquaDams® also meet the demands of EPA guidelines and Clean Water Act laws that prohibit fill discharge.

If an AquaDam® is placed on a soft base which allows water to permeate its substrate and undercut the dam, it will have a tendency to sink as the base is washed out. This problem would present itself with any water retention system. If this problem is a possibility with any given site, it should be considered as a factor in selecting a particular AquaDam® size. A larger AquaDam® provides a larger footprint to resist undercutting and sinking and ensures that the retention depth will stay within recommended values if sinking should occur. Any leakage through the ground or subsurface would be directed to a small pump in order to keep the dewatered areas dry.

Installation time and effort

The US Army Corps of Engineers performed an installation time study comparing sandbag dams with AquaDams®. A group of trained people could install a 4' x 100' sandbag dam in a little over four hours:  Two Corps personnel could install a 4' x 100' AquaDam® in 30 minutes.

The exact number of laborers and time required to install AquaDams® is related to the size of the AquaDam® in question, the worksite terrain, water depths, and water flows. The following chart illustrates manpower required in a typical installation in flowing water:

AquaDam® Size Rope-Assisted Installation Number of Laborers in Water Number of Laborers on Pumps Number of Laborers on Ropes
1-3 feet no 1-3 0-1 0
4 feet no 3-6 1 0
6 feet yes 2-4 1 2
8 feet yes 2-4 1 3-4
10 feet yes 2-4 1 4-5

Are there limitations to the size of the work area within the AquaDams'® retention basin?

It is important that adequate clearance between the work area and the AquaDam® be provided when the retention basin is established. Adequate clearance will reduce the potential threat of puncturing the dam if heavy equipment is used in the work area next to the AquaDam®. Do not crowd your work area, if possible.

Is any additional area outside of the work area required for placement of pumps or other equipment?

No additional area is required outside of the work area since AquaDams® form a platform-like surface when deployed. Pumps, if needed, can be placed on the AquaDams® themselves. Other than water and pumps, AquaDams® do not require any equipment or fill material for maintenance. As long as they remain filled with water they will continue to perform effectively.

Does use in the middle of a stream as opposed to the edges or sides preclude the use of AquaDams®?

AquaDams® have been used successfully in the middle of streams and lakes, as well around their edges. When used in the middle of a body of water, the first AquaDam® serves as a stable platform and work area after it is deployed. Any subsequent AquaDams® required by the project can be deployed with pumps and equipment placed on the first AquaDam®,   thereby eliminating the need for boats to convey the equipment to and from the shores or banks. The fact that the AquaDams® act as a walkway and work platform becomes especially important when work activities are in deep mud.

Cold Weather

AquaDams® will perform in any temperature environment encountered so far, which has ranged from -40F to 120F. At very low temperatures the water inside the AquaDams® will freeze. If attempts are made to remove the AquaDams® under these conditions, the ice inside the AquaDams® will crack and break, exposing sharp edges or points that may puncture or otherwise damage the inner tubes.

Are AquaDams® reusable?

Under most conditions AquaDams® can be reused. Even a punctured AquaDam® can easily be patched. As long as the AquaDam® is not irreparably damaged during the deflation, it can be pulled from the water and stored for another project.