Top 5 Things You Must Know About Geo Tubes

Geotextile tubes (geotubes) are large tubular containers sewn from high-strength geotextile. They are used in many sludge dewatering projects because they are simple to run and cost little. They are the big cousins of geobags, which are smaller sand-filled bags placed by hand or crane. A geotube is filled hydraulically with a slurry, such as sand and water or sludge. The pumping pressure carries the solids along the inside of the tube, the water drains out through the permeable fabric, and the solids settle and stay inside the tube.

Applications for geotextile tube systems include shoreline protection, land reclamation, island building, wetland creation, construction platforms, revetments, dykes, groynes and offshore structures.

The system has no belts, gears or moving machinery. Geotubes come in a range of sizes to suit the volume and the space available, and for smaller jobs dewatering bags can be fitted inside roll-off containers that are moved around the site as needed.

Why Do You Need Geotubes?

To dewater sludge at pulp and paper mills, treatment plants and similar facilities, conventional dewatering equipment such as belt presses or centrifuges has to be brought to site, run and maintained, which takes labour and time. A geotube needs only a pump, a dosing system for flocculant and a small crew. Tubes can be stacked in layers to save space, within the limits of the stacking design. Because there is no machinery to run, geotube dewatering can cost less to operate than mechanical methods.

In dredging work, geotubes are laid out near the dredging area, on land or in shallow water, and the dredged material is pumped into them. The tube holds the material in place and stops it washing away. Capacity depends on the tube’s circumference and length; a single large tube can hold several hundred cubic metres.

On beaches, geotubes filled with local sand are placed to resist erosion. Used as low breakwaters or groynes, they reduce wave energy reaching the shore, which slows the loss of beach. Geotubes can also create new land: a perimeter of tubes encloses an area, which is then filled with dredged material.

What Are The Uses Of Geotubes?

Sludge dewatering is used at sewage plants, pulp and paper mills, industrial plants, and anywhere else solids and liquids need to be separated.

Geotubes are made from a high-strength geotextile that can handle large volumes and be stacked if needed. The fabric’s opening size can be matched to the particle size of the solids so that as much as possible is retained. If the suspended solids are too fine for the fabric to hold, a flocculant is dosed into the slurry during pumping to bind them into larger flocs.

Dredging work that uses geotubes includes shipping channels, water intakes, and berths for vessels with deeper keels. Geotube units can also form shoreline revetments, containment dykes, groynes, jetties and breakwaters. They are quick to deploy and are filled on site with local sand or dredged material, which costs less than importing rock or fill.

Key Features Of Geo Textile Tubes

• The polypropylene or polyester fabric resists biological degradation and most naturally occurring chemicals.
• Compared to rock or concrete structures, they are flexible and usually cost less.
• The fabric’s high flow rate allows fast dewatering.
• Solids are contained, and the filtrate can be collected and treated or returned to the plant.
• Geotextile tube dewatering is used worldwide by small and large organisations.
• Strong seams let the tubes withstand pumping pressure.
• Geotube fabrics are UV-stabilised, though tubes left exposed for long periods are usually covered or protected.

What Is The Process Of Installing Geotubes Technology?

Geotube dewatering runs in three stages: filling, dewatering and consolidation.

Step 1: Filling

The geotube is pumped full of dredged material or sludge. For fine sludges, a polymer flocculant is dosed into the slurry on the way in, so the solids clump together and separate from the water.

Step 2: Dewatering

Clear water drains out through the small pores of the engineered fabric, leaving the solids inside, so the contents lose water and shrink in volume.

As the volume drops, the tube can be filled again, and the fill-and-drain cycle is repeated until the tube is full of solids. A well-matched fabric and flocculant capture most of the solids, and the clear filtrate can be collected and recirculated through the system.

Step 3: Consolidation

After the last fill-and-drain cycle, the solids stay in the tube and keep densifying as remaining water drains and evaporates. The reduction in volume can be large, depending on the sludge. The full tube can then go to a landfill or stay on site, or the dewatered solids can be removed and, where suitable, applied to land.

Advantages Of Geo Textile Tubes

The main advantages of geotextile tubes are:

• They are designed for pumped filling, with seams that withstand the pressure.
• The fabric’s high flow rate lets water drain out quickly, leaving the solids behind.
• Size and fabric can be designed and made to the project’s specification.
• The same system can build revetments, breakwaters, dykes and groynes.

Why Choose Ocean Geo Synthetics As Your Geo Tubes Suppliers?

Ocean Geo Synthetics supplies geotubes in India for dewatering and for coastal and river work. For costs and how the tubes work, see how a geotube works and what geotubes cost.

Our geotube dewatering containers have no mechanical parts. They are made from a geotextile woven from polypropylene multifilament and monofilament yarns. Smaller units can be fitted in mobile roll-off containers and moved where they are needed. For a coastal example of Ocean’s work, see the beach protection project in the Maldives.

Geotubes are one of several ways to hold a coastline. For how they compare with seawalls, groynes, geobags and beach nourishment, see our guide to shoreline protection and stabilisation.

Frequently Asked Questions (FAQs)