Aquamog Midwest
The dedicated dredging site of
All Things Water
1) Dredging of the Water Body Basin- This technique involves the draining of the entire water body, waiting for the basin to dry, then the employing of traditional heavy equipment (excavators, dozers, etc). Once all dredging is complete, then the water body is refilled.
Advantages
· A quantifiable amount of sediment is removed.
· A visual inspection of the basin can verify that the target areas were dredged properly.
Disadvantages
· Undetermined start time for dredging, depending on how fast the basin dries, and the amount of rainfall it receives (remember it must be able to support heavy equipment)
· Undetermined amount of time to refill the water basin (depending on rain fall or drought)
· Loss of Lake Use- During times of dredging the water body is utterly useless for recreation purposes.
· Loss of fish and habitat- Additional costs will incur when the entire fish population has to be replenished.
· In most cases when a water basin is drained the sediment from the center of lake is moved to build out the shore, thus reducing total acreage or square footage of lake.
________________________________________________________________
2.) Dredging from Shoreline- This technique involves the use of long reach excavators or drag line cranes to reach out into the water basin and pull sediment onto shore. Once at shore the sediment is placed in trucks and moved to disposal site.
Advantages
· A quantifiable amount of sediment is removed
· The Water Body does not have to be drained
· Other areas of the lake can still be used
Disadvantages
· Total access to the entire perimeter of the water basin must be established (trees, fences and other obstacles will have to be removed
· The maximum area that can be dredged is based on the length of the arm of the equipment being used
· The entire shoreline area will have to be restored (sometimes taking years to grow back.)
________________________________________________________________
3) Hydraulic Dredging- This technique uses a barge that pumps a combination of sediment and water to a discharge site. The water then effectively drains from the discharge area (spoils pit or sediment bags) and then returns back to the body of water.
Advantages
· There is only one needed access point for the water body (limited shoreline repair)
· Can move large amounts of sediment quickly
· No complete loss of habitat
Disadvantages
· A spoils discharge site must be in close proximity of the water basin.
· In most cases the spoils retention area is not the final disposal site for the sediment, time must be allocated for the sediment to dry, worked, and then removed once again to its final dumping site.
· An adequate water supply from water basin is needed to hydraulic dredge (water is used as a transporter for the sediment at rate of approximately 80%- 90% Water to 10%- 20% sediment). Low marshy areas often do not have enough water in them to transport the sediment.
· Little quantifiable data to conclude if contracted sediment amount was actually removed.
· There is limited mobility in standard dredging equipment. In tight areas these dredges are not efficient because they move on a cable/ winch system (straight lines only)
· Lake access can be limited due to discharge pipe crossing the waters to discharge site.
