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cleaned out periodically. Maintenance is a key factor <br />in effectiveness ofthia treatment.Although protection <br />is immediate, maintaining debris basins maybe a <br />long-term commitment. <br />Straw Wattle Dama <br />Purpose: Straw wattle dame work on the same princi- <br />pal as straw bale check dams. They trap sediment on <br />side slopes and in the upper ends of ephemeral drain- <br />ages byreducing channel gradient. Straw wattles are <br />easy to place in contact with the soil and provide a low <br />risk barrier to soil movement. <br />Relatrve Etfectrveness Excellent-33% Good-67% Fair- <br />0%Poor-0%o (Replies = 3) <br />The limited number of interviewees that rated this <br />treatment scored straw wattle dame as "excellent" or <br />"good" in terms of controlling movement of sediment in <br />channels. In one instance, only 10 of 3,300 wattles <br />failed during the first storm after installation. An- <br />otherreported an 80 percent first-storm survival rate, <br />and excellent channel energy dissipation and trapping <br />of sediment. <br />Implementatron andEnvirunmentalFactors Like any <br />other channel treatment, good plena, designs, and <br />experienced crews go a long ways to ensure successful <br />implementation. Straw wattles work best on first <br />order ephemeral channels with elopes less than 45 <br />percent gradient. They can be easily placed by rela- <br />tively untrained crews since they conform to the soil <br />surface very well. This is a distinct advantage over <br />rigid barriers like logs. Placement of straw wattle <br />check dams is easiest on loamy sand soils that can be <br />readily excavated. The closer together straw wattles <br />are placed in steep terrain the more effective they are <br />in detaining sediment. "L1" shaped re-bar is very effec- <br />tive in keeping straw wattles fastened down but is <br />anotherfactortoconsiderinthelogiaticsplansforthis <br />type of BAER project. Shallow or rocky soils can cause <br />problems with re-bar usage, but hard pane can be <br />penetrated by driving the re•bar. Straw wattle dams <br />are a good alternative in burned areas where loge are <br />absent, poorly shaped, or scarce. Wattles can be used <br />quite effectively in combination with straw bale <br />check dame. They also can be easily prepoaitioned <br />by helicopters. <br />Other Factors Straw wattles are relatively cheap to <br />buy. They canbe disturbedbygrazinganimals, decom- <br />pose, and catch fire. Although the wattle netting is <br />photodegradable, there are concerns that it persists <br />long enough to pose hazards for small animals. Supply <br />is a major problem, particularly for a large project. <br />There are concerns among some users about the coat <br />effectiveness of straw wattle dams since the material <br />and labor costs are quite high. <br />Rock Cagg (Gabionl Dama <br />Purpose: Also known as rock fence check dams, these <br />structures are used in intermittent or small perennial <br />channels to replace large woody debris that may have <br />been burned out during a wildfire. The rock cage dams <br />provide a degree of grade stability and reduce flow <br />velocities long enough to trap coarse sediments. <br />Relatve Etl'ectrveness Not enough interviewees rated <br />this treatment. <br />Comments by some individuals indicated Favorable <br />results. On mild gradients these structures work well. <br />Some failures occurred on steeper slopes when high <br />velocity flows are greater than 3 ft s 1(1 m s 1). This ie <br />a common theme for all channel treatments. Moat of <br />the failures occur where treatments are imposed on <br />steep gradient sections of ephemeral or first to second <br />order perennial channels. Rock cage dame often last <br />long enough and trap enough fine sediments to pro- <br />vide microaites for woody riparian vegetation to get <br />reestablished. Rock cage dame on the Wenatchee Na- <br />tional Forest were very successful, trapping 2000 to <br />10,000 yds (1500 to 7600 ma) of material after just one <br />storm. <br />ImplementatronandEnvironmentalFactors Like moat <br />other BAER channel treatments, proper dam design <br />and installation by experienced crews are crucial to <br />success. The rock cage dame must be properly placed, <br />keyed in, and anchored to stay in place during runoff <br />events. Downalope energy dissipators are recom- <br />mendedbecause they reduce the risk of the rock cage <br />dame being undercut. <br />Other Factors Construction of these structures is <br />dependent on the availability of adequate amounts <br />and sizes of rocks. Rock cage dams need to be <br />cleaned cut periodically if they are to maintain their <br />effectiveness. <br />Road Treatments <br />Road treatments are implemented to increase the <br />water and sediment processing capabilities of roads <br />and road structures. They are not meant to retain <br />water and sediment, but rather to manage its erosive <br />force. <br />Rollins Dius/Waterbare/Cm sa Drain/Culvert Overflow/ <br />Bypass <br />Purpose: These treatments are designed to provide <br />drainage relief for road sections or water in the inside <br />ditch to the downhill aide of made especially when the <br />existing culvert is expected to be overwhelmed. <br />Relative Effectiveness No interviewee rated this <br />treatment. <br />USDA Forest Service Gen. Tech. Rep. RMRS-GTRE3. 2000 83 <br />