If an active pond, lake or lagoon is not practical to effectively agitate or suspend the silt, sand or solids, then dredging is the answer. Due to the amount of equipment and complexity of dredging, this is a more expensive option.
Dredging is the method used for small lakes, ponds and lagoons in the following situations:
• Shallow ponds or lagoons such as municipal lagoons where make-up or return water is available
• Dense sludge or sediment on pond or lagoon bottom such as old lagoons that have not been cleaned
* Lagoons, ponds or lakes with bottoms of sand or heavy sediment that drops out of solution quickly
• Very large lagoons where agitation alone will not suspend solids and sludge long enough for pumping
The process includes a dredging barge with a tiller on a long arm that is lowered to the lagoon or lake floor that loosens the substrate enough for a low pressure high volume centrifigal pump to vacuum up and discharges the water silt, sand sludge mix through a 8" firehose hose that is floated to closest shore line. Then a high pressure centrifigal pump increases the pressure and volume of effluent so it can be pumped to a spot to deposit or store the tailings. This site can be close or even several miles away.
With dredging a barge with a cutter head is put into the lagoon and it traverses the pond or lagoon on a cable that follows a swath or path every 8 feet apart. This dredge is then moved systematically across the lagoon in swaths eating or cutting through a 24" layer of silt, sludge or sediment per pass. This is mixed with water and pumped into the fields through the same hose and drag line injection system as with pumping. Multiple passes are often required on the same swath to reach the desired depth.
Approximately 2 cubic yards of silt or sludge is removed every minute of dredging. This is heavily dependent on how hard packed the silt or sludge is. The dredge is driven into sludge as fast as the tiller tines can break up the sludge and the centrifugal pump can suck up the loosened silt laden water. The drege pumps at 2000 gallons per minute. Ususal forward speed is 5 to 9 feet per minute. Due to unproductive back-ups and uneven silt bottoms the dredge tiller head is only engaged into the sludge about 60% of the time.
Dredging takes a minimum water level of 3 feet above the lake, pond or lagoon floor in order for the dredge to float. This requires make-up water to return water to the pond, lake or lagoon being dredged. This make-up water is often the same water that is used to deliver the sludge or sediment to the final location. In such cases a silt fence or holding basin is constucted to slow down the water sufficiently to allow the sludge or sand to drop out of solution. Then a return pump, drain or line is set up to return the water back to its source. In the case of sanitary waste-water, sanitary sludge or animal waste is land applied, then the make-up water needs to come from a well, another lagoon or another ready source of silt free water.
Lagoon Pumping & Dredging, Inc.
Call the Representative for your Area:
NE, SD, IA, MO, East KS: (402) 270-1366 (Brian Jakub)
TX, NM, OK, CO, WY, MT, West KS: (763) 355-4099 or (806) 683-5553 (Steve Larson)
Main Office: (402) 563-3464
Lagoon Pumping &
4015 S 9th St
Columbus, NE 68601
NE, SD, IA, MO, E-KS
TX, NM, OK, CO, MT, WY, W-KS
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