Note: The scour apron beneath the ENVIROTUBE for foundation support and erosion protection.
Filling Tubes with Sand
When filling an ENVIROTUBE with sand, one fill port is left open to allow the water out of the top of the tube (usually at the opposite end from the fill point). The elevation of this port can be extended to help shape the ENVIROTUBE. The sand entering the tube will form a delta, eventually filling the entire tube. The tube only has to be filled or pumped once. When the tube dewaters there will be very little or no further settling. Special care has to be taken at the filling port to insure a level top with no void at the fill point.
For best results, filling of each ENVIROTUBE should be non-stop. A good slurry mix to pump into the tube is 10% - 15% sand and 85% - 90% water. The water is needed to disperse the sand and carry it down the tube. Fill ports should be spaced every 25-50 feet.
The pressure in the tube is measured by the elevation or height of the tube. Water must be allowed to exit the tube through one or more fill ports while the tube is being filled with sand to control the elevation and the internal pressure. All of the water will not pass through the fabric to exit the tube.
The tube can be filled by a dredge, a pump suspended in a borrow pit, or from a flooded hopper being loaded with an excavator or bucket loader.
A normal fill rate would be 60 - 150 CY per hour. A normal slurry flow rate would be from 1500 - 2500 US gallons per minute.
ENVIROTUBES must be butted against each other for a continuous installation. The tube to be placed is tucked against the filled tube and enough slack is pulled to allow the new tube to form to the shape of the filled tube. This will make a very tight joint. ENVIROTUBES are sewn with handles so the tube can be tied in place to insure proper slack for making the joint.
One tube should never be filled over the end of the next tube to be filled. THe second tube will lift the first tube hydraulically, making a very uneven, ugly, leaking joint.
ENVIROTUBES can be stacked in a pyramid fashion: two on the bottom, and one on top or three on the bottom and two on top, etc. Care must be taken when placing tubes.
Tubes placed parallel to the shoreline provide lasting protection against coastal erosion problems.
If the tube will be exposed to moving water or water pressure of any kind, an apron will be needed to prevent scouring under the tube. If the exposure is only on one side, the apron only has to be on one side.
The scour apron will have an anchor tube sewn into the outer edge. This will be filled like the tube and must extend out past the edge of the tube at least half the width of the tube. Moving water will scour under this anchor tube. It will fall on the hole and protect the large tube from scour.
There are many ways of covering the tubes, depending on what the top has to be. For a dune, the cover can be sand and vegetation. If a road is needed on top, multiple tubes must make up the top and be covered with earth or a concrete mat.
Proper site preparation is a must. There are two major things to address. The tubes love to roll. They must be restrained and level. When installed out of the water, the decant water must be controlled to prevent erosion. You do not have to worry about the water coming out of the bottom of the tube because the bottom fabric plugs right away and the water comes out of the top, upper sides and the open fill port.