Which Sediment or Muck Removal Option Is Best for My Waterbody?
Virtually all explanations of dredging include the physical scooping up of underwater sand and clay sediments to enhance a merchant ship’s access to a port or waterway. If these waterways become inaccessible, the economic consequences are far-reaching.
Today, however, massive algal blooms, animal fatalities from toxic byproducts of algae, and the spread of invasive plants and animals are sharing the front-page news with national economic interests. For those of us living on a waterbody, it’s clear that our personal economic interests are rewarded via higher property values if the nearby water is both navigable and healthy. As a waterbody ages and becomes “silted-in,” organic nutrients fuel invasive plant and algae growth, and property owners suffer the consequences of bright green water, fish kills, and dangerous swimming conditions. Unfortunately, the solution to these rampant biological problems involves more than just scooping up the muck. Hence, we need to look at dredging options and aquatic management in a unified perspective.
Choosing the Dredging Tool for Your Waterbody
Fortunately, there are many proactive aquatic management solutions that can be implemented to help slow or prevent the aging of waterbodies, such as proper land use management, maintenance of beneficial vegetative buffers and sediment traps, installation of aeration systems, and utilization of nutrient absorbing products. However, when sediment buildup is too much to dock a boat or when aquatic plants and algae are perpetually out of control, you’ll need to call in a professional waterbody manager accompanied by a portfolio of dredging techniques.
There are several methods of sediment or muck removal: hydraulic dredging, clamshell or backhoe dredging, dry dredging, and hydro-raking. The chosen method will depend on a number of factors, including sediment composition, environmental sensitivity, the volume of materials removed, budget, and disposal considerations.
Mechanical Dredging
Mechanical dredges (clamshell or backhoe dredgers) use buckets to scoop out bottom sediment and transfer it to trucks or barges for transport to disposal sites. Truck transportable mechanical dredges such as Aquamogs can remove small volumes of sediments such as shoals that prevent boater access to a lake, while large oceangoing dredgers are capable of digging to great depths to facilitate the new era of ultra–large container ships. In the case of the drawdown and excavation method (dry dredging), the whole waterbody is drained and sufficient shoreline access is needed for the trucking and hauling involved. However, most lakes cannot be emptied due to environmental concerns or high water tables.
Hydraulic Dredging
Hydraulic dredges are the workhorse of the dredging industry and are effective in moving large volumes of organic and inorganic sediment. They work by sucking slurry (a mixture of sediment and water) from the bottom and then pumping it to an offshore location through a pipeline. Hydraulic dredges have almost continuous operating cycles, allowing the removal of large volumes of material in a short time while minimizing the resuspension of material into the water column due to their closed-cycle system of operation. Typically, this method is better suited for sediments with little debris mixed in, as large objects and rocks can damage the cutter and clog the pipeline. A large disposal area is also required.
Hydro-raking
Unlike the mechanical and hydraulic dredge, the hydro-rake cannot be used to remove sediment, however, it is an effective tool for accumulated muck removal. Hydro-raking is frequently chosen as a method to remove nuisance aquatic vegetation, root structures, debris, and organic muck on a smaller scale waterbody. The hydro-rake can best be described as a floating barge upon which is mounted a backhoe with a digging bucket or rake capable of removing accumulated muck in water as shallow as 18 inches. Hydro-raking can effectively target organic muck accumulations and debris in coves, stormwater ponds, and other shallow areas. If a pond is periodically maintained through hydro-raking, the need to perform a large-scale dredging project may be eliminated, saving financial resources and minimizing ecological disruptions.
How to Maintain Balanced Water Quality
Dredging is generally thought of as an expensive activity, but both your waterbody can benefit significantly from just a few days of budget-friendly spot dredging at pump intakes, swimming areas, or around boat docks. However, the ultimate cost-savings approach is proactive management. By taking preventative steps to reduce erosion, limit weed and algae growth, and maintain balanced water quality, it’s possible to prolong the need for both dredging and hydro-raking. The best way to accomplish this is through an annual management program that leans on sustainable strategies like aeration, nutrient remediation, shoreline maintenance, and many other custom solutions to maintain a healthy, functional waterbody.
To learn more or navigate through a wide variety of sediment, aquatic plant, or algae removal options for your waterbody, we encourage you to speak with your lake or pond management professional.
