Types of Dredging

Most dredging performed on inland lakes throughout the midwest falls under the following two categories:

MECHANICAL DREDGING: While often more appropriate and preferred for smaller jobs, mechanical dredging can be quite destructive. Ideal for pier cleanout and stormwater ponds. It may also be a necessity if substrate is heavily consistent of sand or gravels which my exist from stream loading. The tough realization is that you are paying to haul off a high percentage of water and the continual access with construction equipment; particularly dump trucks can be difficult with access limitations and furthermore weight limitations. Safety can also be a concern.

HYDRAULIC DREDGING: There becomes a price point where the inefficiencies of mechanical dredging become exposed and hydraulic sediment removal becomes the more appropriate method. The trick to obtaining the efficiency however comes with the added cost of permitting to sites, typically one for the in-lake activity and the other for the dewatering/disposal area. If you cannot or are unable to dispose of at or near the dewatering area, you have the potential complication of working on three fronts. The permitting and planning become essential but at a certain job site the efficiency is quickly realized because the moved sediment volume is greatly reduced saving on contractor costs.

Either one of the above requires planning.



Regardless of the eventual method of sediment removal or recovery, there are some very simple, up front strategical logistics that need to be performed in order to make informed decisions regarding the project:

1. Estimate sediment depth
2. Determine sediment constituency
> Is the material clear of toxins of concern?
> What is the makeup of the material?
3. Under 1,000 CY?
> Candidate for mechanical sediment removal
> Candidate for diver assisted small hydraulics removal
4. Over 1,000 CY?
> Start considering mechanical means
> Where can sediment be dewatered?