Frequently Asked Questions
(Click on any of the topics below)
AquaDam® cofferdams are a simple, effective, and environmentally-friendly water
retention system. AquaDams® are
ideal for:
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 temperatures as low as -200F and
can operate at -600F
with a cold weather vinyl option. 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.
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