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<br />deflected into the main channel. This technique Is useful If the stream has a heavy <br />debris load and the designer desires to keep the banks clear. Conversely, the fence can <br />be constructed so that it is oriented upstream at an oblique angle to the current flow. <br />Debris is then trapped behtnd the fence. This construction method is effective for <br />clearing the main channel of debris and serves to encourage sediment deposition. <br /> <br />ADVANTAGES: <br /> <br />1) Directs energy of river from bank to open channel. <br /> <br />2) Collects debris to slow current and promotes siltation. <br /> <br />DISADVANTAGES: I) Length Is limited so not to Interfere with navigation. <br /> <br />2) Susceptible to Ice damage. <br /> <br />3) Costs are high. <br /> <br />4) Maintenance costs high. <br /> <br />COSTS: $54/bank-foot of protection. <br /> <br />MAINTENANCE REQUI~MENTS: Periodic repairs of damaged fence sections. <br /> <br />ENVIRONMENTAL ASPECT: Fence jetties are constructed of wood and spaced in paral lei rows <br />perpendicular to the bank. The jetties are designed to deflect the current flow and to <br />collect sediment and debris. After a long pertod, vegetation will establish in the <br />sediment buildup area. The value of this erosion control method to wildlife and fish is <br />limited. The structure Is visually unappeal tng. The Impact on the existing vegetatlon <br />would be minimal. <br /> <br />28 <br />