Written by Industry Expert Lance Dohman, Regional Manager
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.
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 with a portfolio of dredging techniques.
There are several methods of sediment removal: hydraulic dredging, clam shell/ backhoe dredging, dry dredging and hydro-raking. The chosen method will depend on a number of factors including sediment composition, environmental sensitivity, volumes of materials removed, budget and disposal considerations.
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 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.
Mechanical dredges (clam shell or backhoe dredgers) use buckets to scoop out bottom sediment and transfer it to trucks or barges to be transported 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.
Hydro-raking is frequently chosen as a method to remove nuisance aquatic vegetation, root structures, debris and soft organic sediment 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 sediment accumulations in coves and other shallow areas that provide nursery sites for aquatic plants and algae. If a pond is periodically maintained through hydro-raking, the need to perform a large-scale dredge project may be eliminated, saving financial resources and minimizing ecological disruptions.
While dredging is generally thought of as an expensive activity, both your waterbody and your real estate portfolio benefit significantly from just a few days of budget-friendly spot dredging at pump intakes, swimming areas or around boat docks. To 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.
Contact the experts at 888-480-LAKE (5253) for all of your lake, pond, wetland and fisheries management needs.
Lance Dohman is the Regional Manager of SOLitude’s California market. He is responsible for the management of operations in the region, focusing largely on proposal development and cultivating lasting relationships with clients. His expertise includes flood prevention strategies, mosquito management, new lake and water feature construction, renovation of historic decorative fountains, invasive species management, and wetland restoration. Prior to joining SOLitude, Lance served as the President of Aquatic Environments, Inc for 14 years.
SOLitude Lake Management is a nationwide environmental firm committed to providing sustainable solutions that improve water quality, enhance beauty, preserve natural resources and reduce our environmental footprint. SOLitude’s team of aquatic resource management professionals specializes in the development and execution of customized lake, pond, wetland and fisheries management programs that include water quality testing and restoration, nutrient remediation, algae and aquatic weed control, installation and maintenance of fountains and aeration systems, bathymetry, shoreline erosion restoration, mechanical harvesting and hydro-raking, lake vegetation studies, biological assessments, habitat evaluations, and invasive species management. Services and educational resources are available to clients nationwide, including homeowners associations, multi-family and apartment communities, golf courses, commercial developments, ranches, private landowners, reservoirs, recreational and public lakes, municipalities, drinking water authorities, parks, and state and federal agencies. SOLitude Lake Management is a proud member of the Rentokil Steritech family of companies in North America.