Cofferdams for temporary works in rivers | Water-Gate© dams 2016-10-16T10:14:33+00:00

Is the Water-Gate© cofferdam for your project?

Water Works – river – channel – pond

On concrete, we recommend using the WL© range with ballast integrated rather than the WA© range of cofferdams.
Sandy bottom, it is imperative to bury the leading edge of the water barrier to limit the hydraulic piping erosion effect.

Seepage under the cofferdam depend on soil type and height of retained water. The seal can be improved by slightly burying the leading edge of the dam.

The filling operation of the cofferdam in water depends on the current strength.
The stronger the current, the more people are required to coordinate the impoundment of the dam.

The strengths of the flexible Water-Gate© cofferdam

Cofferdam Installation Perpendicular to the Water Courses

Landfill work in river – Excavation – Block a river arm – Total river dam – Canal dredging work – Culverts dewatering – Renovation and locks maintenance

This is the fastest and most spectacular setup. Cofferdam pressurization is instantaneous.

Water-Gate© fits all river beds: thanks to its exceptional flexibility, the cofferdam follows the banks and the stream bottom no matter its relief.
Water-Gate© offers an excellent sealing due to the pressure that the water exerts on the bottom canvas.
In low slope, it is recommended to set up two cofferdams upstream and downstream of the dry zone.

In water maneuver

Unroll cofferdams, unfold them, tie them together.
If the length of a single cofferdam is sufficient, place it directly across the river and unfold.
Otherwise, pull the pre-attached cofferdams across the river by keeping the leading edge out of the water.
Center the cofferdam in the middle of the river, ensuring that the ends back on the banks.
Dip the leading edge to the river bottom.
Standing on the leading edge until the cofferdam is pressurized by water.
Ballast the leading edge of the cofferdam with sand bags or stones taken from the river.
If the river banks are vertical tie the ends of the cofferdam so they do not fall into the water.

U Cofferdam | Installation Parallel to the Water Courses

Repair or renaturation of river banks – Piping – River diversion – Dry work on bridges, culverts, dams, mills, fish passes, other hydraulic structures

This is the installation that should be used for water works that use only a section of the river and can not be completely blocked.

The Water-Gate© cofferdam can be bent in all ways and all directions : ideal for the rehabilitation of banks! Water-Gate© is effective no matter the length. It can be extended at will.

In water maneuver

Unroll cofferdams, unfold them, tie them together.
Pull the cofferdam on water to the desired location while maintaining the leading edge out of the water. Position the cofferdam as desired (L or U).
Dip the leading edge to the river bottom.
Standing on the leading edge then ballast.
Moor the metal rings of the leading edge with stakes to prevent slippage until cofferdam is fully on pressure.
Start pumping space to dry.

Cofferdam Free Installation in Sleeping Waters

Dredging ponds – low water velocity channels – Port works – Swamps

The Water-Gate© cofferdam can be bent in all ways and all directions: ideal for draining a pond in the desired path.

Sleeping water maneuver

If the bottom is covered with a thick layer of mud, we strongly recommend te remove the mud / vase before installing the cofferdam.
Unroll cofferdams, unfold them, tie them together.
Pull the cofferdam on water to the desired location. The cofferdam then floats to the surface.
Dip the leading edge to the bottom of the pond / canal.
Put pickets (12 mm rebar) in the metal rings attached to the leading edge.
Plant pickets in the bottom (minimum 50 cm) to secure the cofferdam.
This operation may require the use of divers beyond 1.20 meter water height.
Position a ballast all along the cofferdam.
In order to limit the risk of leakage under the cofferdam we recommend to bury the leading edge by digging a small ditch of 15cm depth.
Start pumping the space to dry.
The water will be pumped beyond the cofferdam if high enough.

Water diversion – Evacuation – Downstream Piping

Thanks to the flexibility of the Water-Gate© cofferdam, it is possible to integrate without leakage any type of pipe directly over the dam.

Megasecur™ has also developed a dedicated spillway for small evacuations (90 liters per second), ecological, without pump, with a hose to drain water downstream. Several spillways can be positioned side by side if necessary.

Spillway installation maneuver
The spillway or Le déversoir or transition pipe is in two parts: the spillway itself and the main flexible tube. Very easy to handle. Set by one person in few minutes.

Plan to bring the tube beyond the area to be dried to prevent backflow (provide additional hose 15m). The slope and current strength will help you determine the extension length if necessary.
The spillway has a funnel shape to siphon and evacuate as much water as possible.
The main tube adapts to the output of the spillway.
The main tube has got straps for better handling and to direct the water to the desired location.
This 22.7 meters flexible tube molds perfectly to the terrain and sinuous shape of rivers.
The tube is made of polyethylene abrasion resistant.
If necessary add tube extensions.
The float inside the spillway has a stabilizing effect.
We recommend adding few boulders found locally or sand bags on top of the spillway in order to maximize the suction effect and further improve stability.

WA : A Complete Range Of Flexible Cofferdams for Professionals

Unlimited lengths and anti flood protection heights of up to 1.5 meters !

scheme of the watergate cofferdam for aquatic works in river
*       Cofferdam designed without ballast: the flexible leading edge fits perfectly uneven ground
**     Exclusively for implementation in backwaters
***   A deep ground sheet that facilitates pedestrian passage and pumping without risk to the hoppers
**** Limit the risk of erosion especially on sandy bottom in case of overflow
WA 211553 cm4,6 m12 Kg
WA 213053 cm9,1 m23 Kg
WA 215053 cm15,2 m38 Kg
WA 281571 cm4,6 m18 Kg
WA 282571 cm7,6 m30 Kg
WA 283571 cm10,1 m41 Kg
WA 285071 cm15,2 m57 Kg
WA 3930100 cm9,1 m75 Kg
WA 3950100 cm15,2 m124 Kg
WA 5050130 cm15,2 m158 Kg
WA 6030150 cm9,1 m114 Kg
WA 6050150 cm15,2 m182 Kg

scheme of the spillway for water-gate cofferdams - channel a river
*   unbreakable polyethylene
Dimensions38 cm x 61 cm x 100 cm
Weight14,5 Kg
Diameter45 cm
Main tube
Length22,7 m
Weight11,4 Kg
Diameter45 cm