What Does a Hopper Dredger Do?
Dredging a lake, dredging a river, or canal dredging requires a set of specialist equipment like drag heads and suction pipes. These are used to remove organic sediment from lakes and ponds or other bodies of water that require dredging work. Litter and other debris is removed in the same process. Dredging projects improve water quality and prevent buildups of toxic gases that can occur on the bottom of ponds, canals and rivers.
Dredging is not only important for maintaining waterways, lakes and ponds, but it also has eco-friendly benefits. As silt and sediment wash downstream, they can build up to levels unsafe for fish and other animals. Plants can find it difficult to thrive in water that has too high levels of sediment. The problem is made even worse if dredging has been neglected for several years, or if the sediment is contaminated or filled with pollutants.
Without regular maintenance, including dredging, ecosystems can struggle. The quality of water is reduced and bacteria can spread making the area unsafe and unpleasant. Dredging is a necessary task to be carried out regularly to ensure that all who use the water can enjoy doing so with fewer risks.
When deposits build up, it can become a flood hazard as well. Enough of a buildup can grow into an obstruction that will cause water to spill over its banks. During periods of heavy rainfall, this can lead to flooding which can be extremely dangerous and cause extensive property damage that is costly to repair.
The action of dredging is similar to scooping. Unlike a trailing suction hopper dredger (TSHD) which works like a vacuum cleaner, most mechanical dredging involves physically scooping material deposits. Water is allowed to run off so excess fluid is not needlessly transported to the discharge site.
A hopper is a container for loose material. In the case of hopper dredgers, the hopper contains the silt, litter, and plant matter removed when dredging a pond. Once the dredging is complete, the hopper is transported to an appropriate location for emptying.
There might be special safety or environmental considerations to take into account when emptying a hopper. This depends on what has been dredged up during the project.
Hoppers are emptied at discharge sites. Assuming the silt is uncontaminated, it can be dried and transported via lorries to farms. It can then be reused as a healthy natural fertiliser.
The Canal & River Trust and other environment agencies work with contractors like The Rothen Group (TRG) to carry out dredging activities. This may include hydraulic dredging, mechanical dredging, or even land reclamation. A hopper dredger is most often used in maintenance dredging.
Dredging a canal is not as simple as dragging up deposited material and placing it in a hopper to be removed. Canals are lined with a special clay called puddling clay. This is a vital part of a canal’s ability to function as it prevents leaks into the surrounding earth.
If a dredger, digger, or long reach excavator were to break the puddling clay, it could cause a very expensive leak. Because of this, it is important that dredgers are operated by highly trained experts.
Depending on the site, dredging equipment may be able to be placed on the river or lake bank. At other times, where access to the site is more difficult, TRG uses its fleet of workboats to transport machinery. Cities that have canals running through often need to be accessed via the water, as walkways and towpaths are not suited to transporting heavy machinery. Once in the right place, hydraulic powerpacks extend four stability legs into the riverbed or lakebed, keeping the equipment level and safe to work with.
From waterways maintenance to towpath construction, it is vital to consult with experts on every type of marine engineering, including hopper dredging. TRG, for example, can provide expert guidance on equipment rental and give specialist advice on bespoke marine projects.