As NOAA’s National Ocean Service so adequately phrases it: “Dredging is the removal of sediments and debris from the bottom of lakes, rivers, harbors, and other water bodies. It is a routine necessity in waterways around the world because sedimentation—the natural process of sand and silt washing downstream—gradually fills channels and harbors.” https://oceanservice.noaa.gov/facts/dredging.html
In addition to sand and silt washing downstream, sediment can also build up following a storm (due to strong winds and wave action) and will eventually find their way into harbours and channels, the term is also known as infilling. The act of dredging material in a marine setting (i.e.: marine dredging, a.k.a. coastal dredging) is a critical service for our economy and for countless livelihoods as it ensures the minimum depth required for vessels to enter harbours safely can be maintained, allowing for commercial activities such as shipping of goods, commercial fisheries and docking of cruise ships to carry-on (among others). Dredging is also used to “mine” sand and aggregate, which can then be used for land-based applications, or for beach nourishment, coastline rebuilding and land reclamation for new infrastructure.
The same can be said of pleasure craft enthusiasts. If maintenance dredging is not performed regularly, a sailboat may not be able to access a safe harbour as a storm approaches because there is insufficient draft (and the keel may be severely damaged if the docking is attempted).
So – what is the objective of dredging? Any dredging operation, regardless of methodology, typically calls for the excavation of a target area to a specified grade (depth) below a recognized vertical benchmark, such as a geodetic landmark.
Conventional dredging in a nutshell:
As opposed to hydraulic dredging (which we will explore in another post), conventional dredging is the most common dredging method. It refers to dredging that is executed using various types of conventional equipment such as excavators and/or cranes equipped with a mechanical bucket (e.g.: conventional bucket, clamshell, etc.). Conventional dredging projects can be land-based (i.e.: equipment operates from land or from off the wharf wall), they can be barge-mounted (in which case the equipment operates from a floating barge) or even executed from temporary roads built into the waterbody in certain jurisdictions.
Conventional dredging is usually the preferred methodology when dealing with coarse material such as gravel, cobbles, hardpan and bedrock removal (bedrock can sometimes require the use of explosives prior to excavating). Since coarse material is not well-suited for pumping applications, the most efficient means of extraction is to excavate and dump into barges, scows or directly into trucks for disposal in a pre-approved location. The same method can apply with regards to contaminated material, as in the project presented in the video below.
What does ECO Technologies bring to this market?
Our fleet of amphibious excavators are barge-mounted and self-propelled dredges that can execute a variety of aquatic interventions in a wide array of conditions, including conventional excavation in very shallow areas that cannot (should not) be accessed using land-based equipment or typical barge-mounted equipment.
Take for example the video presented below where some very shallow dredging is taking place in a navigation channel that was completely infilled during a storm. This specific technique is called side-casting, as the material is being “cast aside” in order to open a channel quickly for fishermen to go out (and come back) safely.
When it comes to conventional dredging, our teams have executed numerous projects in a variety of harsh, challenging and sensitive settings, whether natural habitats or industrial properties.
Do you have a conventional dredging project in shallow waters? How can we help?
Note: The above content is only meant as a high-level summary and is in no way intended to represent an in-depth or scientific review of the subject matter.
ECO Technologies Ltd. is a dredging and environmental services provider located in New Brunswick (Canada), with project management and development offices in Belo Horizonte (MG – Brazil) and Santiago (Chile). Learn more about ECO Technologies on our website: www.ecotec.ca
Original post on Linkedin: https://www.linkedin.com/pulse/marine-dredging-conventional-wayne-powers/