How to Dredge Dirt From a River Bottom

Instructions

• 1

  Apply for a dredge permit in accordance with the Federal Clean Water Act of 1976, which requires a permit for "any body of water more than 10 acres in size including contiguous wetlands and any flowing stream." Call the nearest office of the United States Army Corps of Engineers to find out who handles applications in your area.

• 2

  Make sketches of your work plan and obtain an engineering survey to depicting how deep you plan to dredge. These will accompany your permit application.

• 3

  Choose a dredging contractor based on the company's experience, references, equipment, ability to provide a bond and its project and safety record.

• 4

  Transfer the dredge--a large flat-bottomed boat--to the river. Use a GPS system, in conjunction with the survey work done earlier, to calculate the location of the dredge in the river in relation to the channel and the shoal to be removed. Display this information on a computer monitor on the dredge to help you navigate.

• 5

  Anchor the dredge in place using two spuds, or poles, at the stern of the dredge. Drop the spuds alternately; they function as pivots, allowing slow forward movement as dredging progresses.

• 6

  Lower the ladder to the river bottom so the rotating cutter head, or auger, sits in the sediment to be removed.

• 7

  Turn on the diesel motor for the auger. The auger then rotates and agitates the sediment, similar to an egg beater. The motor also activates a centrifugal pump that sucks up the sediment and water (called spoil) through a pipe behind the auger, and forces it to the discharge pipe at the rear of the dredge.

• 8

  Direct the spoil to the discharge site by means of the discharge pipe. Have a crew there use earthmoving equipment to spread the spoil, which is ideally about 85 percent water.

• 9

  Construct a drainage channel with a spillway to allow the water to return to the river as it filters out of the spoil.