Shoaling Prevention Systems

Shoaling Prevention Systems An innovative alternative to maintenance dredging

Natural Equilibrium

Dock Owners’ Concerns With Dredging `

High & rising cost

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Limited number of disposal area options

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Time Investment

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Environmental Concerns

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Scheduling conflicts

Standard Dredging Techniques `Mechanical `Clam

Dredging

Shell/Bucket Dredge

`Consolidated `Higher

Materials

Impact on Water

Quality `Hydraulic

Dredging

`Cutterhead/Hopper `Unconsolidated

Dredge

Materials

Shoaling Prevention Approach Suspended Sediment Turbo Unit

Ambient Current

Jet Discharge Mud Bottom

System Operation Ebb Tidal Current

Turbo Units (4 Total)

Flood Tidal Current

Dock Control House

Shoreline

Operation is synchronized with the tides

Environmental Concerns `

`

`

Adjacent shoaling impacts `

Near-Field

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Far-Field

Water quality impacts `

Turbidity

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Dissolved Oxygen

Marine organism impacts `

Fish Entrainment

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Benthic Impacts

Near-Field Shoaling Monitoring

Wilmington, NC installation

Far-Field Shoaling Monitoring

11

1 10

Grays Harbor, WA Installation

9

8

7

6

5

4

3

2

NTU

Turbidity

Dissolved Oxygen Dissolved Oxygen (mg/l) 0.00

1.00

2.00

3.00

4.00

5.00

6.00

0.0

2.0

Water Depth (m)

4.0

6.0

8.0

10.0

12.0

14.0

16.0 Savannah, GA installation

Jetting No Jetting

Dissolved Oxygen `

Dredging decreases D.O. levels up to 83%

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Slower currents result in less vertical mixing

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Water is more oxygen rich closer to the surface

`

Oxygen injection option

Marine Organism Impacts - Fish `Hydraulic `Adverse

Dredging

Impact on Water Quality

`Entrainment

Rate of up to 0.594 Fish per Cubic yard (