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The Dewatering Dilemma

Dewatering is one of the biggest obstacles facing dredge contractors around the globe. A standard dredge discharge area is constructed by hauling in dirt and constructing a 4 earthen wall containment cell to decant the dredge spoils. The silt, sand, or sediment settles to the bottom of the pool and the clear water is decanted at the appropriate time through a weir box release system or decanting pipe. This is a time consuming and expensive process, but it is how the majority of spoils are dewatered globally.

In the past two decades the use of geotextile containers, commonly known as geotextile bags, has grown significantly. Geotextile containers are synthetic woven fabric that is formed into a tube and then a dredge discharge pipe/hose is connected to the ports on top and the bag is filled with the slurry. The material settles in the bag and the water filters through the fabric and usually comes out clear if the proper fabric is selected. This process usually requires dozens of bags to be filled in parallel using a manifold that diverts the flow of the slurry through a series of knife valves. Geotexile containers are a popular method for dewatering, but they are expensive and not reusable.

A growing trend in the industry is mechanical dewatering devices that are road transportable and contain a series of de-sanders, de-silters, and hydro-cyclones. These systems can match the slurry feed of a hydraulic dredging system and is scalable meaning you can connect multiple units in tandem.   These systems will dewater slurries down to 25 micron, but then they require additional clarifying technologies to remove the smaller particles (usually fine organics under 25 micron) from the effluent discharge. Polymers, heaters, or other systems are using with clarifying tanks and other devices. These systems are successful, but the price tag starts at $500,000 to $4,000,000 USD for a complete system that can dewater to clear water. GeoPools have solved the dewatering dilemma.