Dredges are often used to clean contaminated areas to restore the areas to non-contaminated levels. Hydraulic transfer of contaminated sediments has become known as the most cost effective and efficient way to restore contaminated areas.
Dredging rivers helps prevent flooding by providing a place for water to drain; this is particularly true in areas like Asia where monsoon rains can wipe out whole areas. Dredging reduces plant biomass and algae as seeds on the bottom will not get enough sunlight to grow. This also benefits fish as the plants will not take all the oxygen out of the water.
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Dredges used in mining processes may include the largest variety of applications, but they are rarely considered a major part of the dredging industry. The layman does not think or even know about these dredges because they are seldom seen. For example, aggregate dredging operations exist all over the USA; however, the high walls, levees, or berms that protect them also hide the dredges from view of a passerby.
The mining of sand and gravel is critical for a country’s infrastructure. Roads, highways, buildings, and residences are all affected by the production and processing of sand and gravel.
Dredges are also heavily used in the minerals mining process. This includes well-known minerals such as gold, diamonds, and other commodities. Other less commonly known mining dredge applications include Titanium Dioxide (TiO2), Phosphates, etc.
Think of where we would be with without these commodities. We would still be riding on dirt roads and our highways and interstates wouldn’t even exist. And titanium dioxide, although not well-known, is actually an ingredient in many of the cosmetic products we use daily, such as sunscreen. It is also used as the white pigment in paint.
Waterway navigation encompasses port development, port maintenance, waterway creation, and waterway maintenance. This not only applies to rivers or sea ports, but also to lakes, streams, and marinas. While smaller lakes and streams are generally referenced as recreational dredging, they still play a major role in dredging, and have an effect on local economies. Typically, the general population sees a dredge as an underwater vacuum cleaner and most commonly associates them with port or waterway maintenance.
Ironically, the main reason the global economy has grown is due to the development of port systems around the world. In fact, no other single factor has prompted continual growth of the world’s nations; both in their economies and in their nations’ overall well-being. Without port systems, the only form of trade would be the barter system. Without proper funding, port systems would decline, along with the region’s overall economy.
A simple definition of dredging is the subaqueous or underwater excavation of soils and rock. The process consists of four phases:
- vertical transport
- horizontal transport
- placement or use of the material dredged.
From the beginning of civilization, people, equipment, materials, and commodities have been transported by water. To do this, the channel depths of many waterways needed to be increased to provide access to ports and harbors. Most major ports in the world require dredging at some time to enlarge and deepen access channels, waterways, and turning basins, and to provide appropriate water depths along waterside facilities. These channels often require frequent and regular maintenance dredging. In the case of fluvial navigation, dredging is also required to construct and maintain vital links to inland ports and facilities.
As population density along the coastlines and riverbanks increases, dredging is also used for to protect against flooding and erosion, as well as to create recreational facilities like beaches through sand nourishment.
Dredging is also used for the installation of energy facilities such as offshore drilling platforms and oil and gas pipelines and the construction of wind farms in the water. Dredging can also be used to recover minerals, gems, precious metals, and fertilizers, or the removal of overlying material to reach such deposits.
Dredging can also provide construction materials such as sand, gravel, shell and clay, or provide landfills, including the construction of industrial and residential areas, highways, dams, airports, causeways and habitats for birds and other forms of wildlife.
Another more recent use of dredging is to remove or remediate subaqueous pollutants and improve water quality and sediment habitats. This type of dredging operation is used as a means to clean-up contaminated waterways. Environmental dredging is the removal of contaminated sediments from a water body for purposes of sediment remediation.
contributed by: Craig Vogt