Removing Fine-Grained Sediments from Urban Waterways

Fine-grained sediment accumulation in urban waterways, including lakes, rivers and detention basins is a common concern in urban areas. It is a common cause of waterway impairment in the United States as noted by the U.S. Environmental Protection Agency (USEPA). As more stormwater regulations are adopted across the nations that control both the quantity of water runoff and the quality of water runoff, man-made stormwater lakes have also accumulated large quantities of sediments that need to be removed. However, removing the sediment is often very difficult as the surrounding urban uses can make typical mechanical or hydraulic dredging operations very difficult or impossible to stage. With the widespread use of polymers, some techniques are emerging to remove fine-grained sediment hydraulically without the use of the large multiple acre confined disposal facilities commonly used for dewatering the dredge slurry. This paper describes some techniques that has been effectively used for rapidly dewatering dredge slurry in urban areas, for large sediment volumes, resulting in reusable or truckable solids.