Laserfiche WebLink
<br />def I ected into the ma r n ctlannel. Th Is techn i que Is usefu I I f 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 ang Ie to th'9 current flow. <br />Oebr I s is then trapped beh i nd the fence. Th I s construct i on method J s ef feet I ve for <br />clearing the main channel 01 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) CoI lect~ debris to slow current and promotes siltation. <br /> <br />DISADVANTAGES: 1) 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 prctectlon. <br /> <br />MAINTENANCE REQUIREMENTS: P.rlodlc repairs of damaged fence sections. <br /> <br />ENVIRONMENTAL ASPECT: Fenct~ jetties are constructed of wood and spaced in parallel rows <br />perpend i cu I ar to the bank. The jett i es are des I gned to def I ect the CUrrElnt f I ow and to <br />collect sediment and debri;. After a long period, vegetation will establish in the <br />sediment buJ ldup area. The value of this erosion control method to wi ldllfe and fish Is <br />limited. The structure Is visually unappealing. The Impact on the existing vegetation <br />would be minimal. <br /> <br />28 <br />