GEOTEXTILE TUBES
Product Description
Geotextile tubes have been used in a variety of environmental dredging applications. By using these tubes, dredged material can be more rapidly de-watered decreasing costs and reducing transportation to the disposal facility.
High strength polypropylene and polyester fabric is sewn into tubes. Each tube has a series of ports on the top allowing liquids to be pumped into them. The tubes are designed to filter out solids and allow the clear water to flow out. Tubes are made in a variety of sizes to accommodate a range of flows and solids volumes. The fabric is a high strength woven polypropylene fabric with machine and cross machine direction wide width tensile strengths of 400 and 600 ppi correspondingly.
Applications
Geotextile tubes are used to dewater dredged materials. Dredged materials are pumped directly into the tubes from the dredge. The fine grained materials are contained in the tube as the water passes through. Flow into the tubes may be alternated to allow the sediment time to settle. Tubes can also be pumped full of non-contaminated sediment or sand to create a dike. Tubes may be stacked within the dewatering area to induce further consolidation and decrease area required for dewatering.
Size Selection
Tubes are selected based on the in-situ volume of dewatered material that must be contained. The size of the area available for the dewatering process and the desired duration may also be taken into account when selecting tube sizes. Fill Port Spacing: If the dredged material is greater than 85% sand fill ports should be spaces at 25’. If the dredge material is less than 85% sand (15% fines) then fill ports may be spaced a greater distance up to 50’.
Dewatering Rates
Generally as the rate of pumping into the tubes increases effluent quality decreases. Dredge material is pumped into the tubes at a rate which optimizes the performance of the tubes. This is often determined by trial, based on job specific conditions. Alternately hanging bag tests may be conducted to determine an allowable range for total suspended solids. To improve the rates of dewatering polymer flocculants may be added while the dredged material is pumped into the tube.
Filling
Hydraulic pumps or dredges should have a maximum 10” diameter discharge hose with a maximum pressure of 5 psi. Typically pumps should not be rated higher than 200hp.
Tie Downs
Tying down the tubes during the operation is recommended. Tubes are supplied with tie-downs built in.
ASSOCIATED DOCUMENTS
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