Over time bodies of water will develop sedimentation at various locations. Typically, this sedimentation comes in the form of sand and silt that is washed in from rivers. To provide enough clearance for boats and vessels and allow access to and from marinas or docks it may be necessary to dredge these areas. Horizontal dredges are the preferred machine for small marinas and boat slips, while cutter suction dredges are usually reserved for larger scale applications with deeper bodies of water or limited ability for a cable drive system.
When rivers and canals become impassable due to sedimentation, dredging is used to facilitate boat and barge traffic or aid in flood control. In this application the cutter suction dredges are the machine of choice as they are capable of high pumping volumes and the spud drive mechanism provides much needed stability in faster moving currents. Horizontal dredges are typically utilized in canals or rivers when the space is too limited for the larger cutter suction dredges, or to create a suitable space where a cutter suction dredge may be put into service for the largest portion of the work.
Horizontal dredges are used exclusively in municipal waste applications. Most lagoons are lined in some fashion (typically HDPE or Clay) making the cutter suction dredge virtually useless. Due to the organic nature of lagoons, there is potential for gases to be released during the dredging process. The horizontal dredges can handle higher amounts of entrained gas without creating cavitation issues.
Industrial ponds typically contain hazardous and/or corrosive chemicals (very high or low pH) that are harmful to both the machine and operator. Mechanical dredging is messy and may result in reportable incidents without a containment area, while hydraulic dredging contains these hazardous chemicals in a pipeline limiting potential contact with operators. Placement of mechanical options near a body of water can pose safety issues that may violate federal, state, or site polices. However, using dredges allows the operator to work safely on the water or the pond bank when using remote options, further limiting personnel exposure to mobile equipment. Dredge equipment can be customized to better handle these harsh environments.
The process of recovering materials we use in our everyday lives creates a large amount of slurry and tailings. Retention ponds are constructed to house these byproduct and cool process waters. These ponds are engineered either in size, shape or both to allow for settling of suspended solids, as pond capacity diminishes, the most cost-effective solution to regain capacity and cooling effect is to dredge this material. Due to the strict EPA guidelines governing product containment on mines these ponds are typically lined with a durable HDPE liner, this in turn makes mechanical dredging near impossible without damaging this liner. Horizontal dredges are extremely effective at removing material from lined ponds without damaging liners when utilizing depth gauges along with gauge wheels to avoid cutterhead contact with the liners.
Both horizontal and cutter suction dredges are used to facilitate operations in power plants. Dredging is used to remove sedimentation in nuclear power plant water intake structures. Coal fired plants create waste in the form of ash. Dredging is used to remove ash from storage ponds for disposal.
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