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• The other type of guly which may form on sideslopes is from sheet wash. Occasionaly sheet wash <br />may form concentrated flows because of the irregularities in the retopsoiled topography. These types <br />of gullies should not be confused with gullies which occur in drainageways. (See Section 4.8.1.3 for <br />definition of permanent drainageways and their tributaries and how they differ from sideslope gullies.) <br />Erosion control designed to prevent the formation of sideslope gullies will commence with the final <br />grading, which will be done along the contour 'rf it does not present a safety hazard to the operator or <br />equipmern. Similarly, seedbed preparation and drill seeding will be conducted on the cornourtf it can <br />be done safely. <br />Runoff diversion ditches or other similar structures will be placed on all reclaimed rangeland sideslopes <br />where potential for excessive sideslope gulying exists by the end of the first fall following topsoil <br />replacemern. These structures may be established with any of several pieces of equipment including, <br />but not limited to, aglow, adozer, arear-mounted tractor blade, or a specially built cornour furrower. <br />During the year of diversion ditch installation,rf the vertical distance between diversion ditches is <br />greater than 75 feet, cornour furrows may be installed between the diversion ditches. Further, if the first <br />• season of runoff after retopsoiling and seeding produces significant gutty development, then contour <br />furrows or additional diversion ditches or other preventative measures may be installed. Where contour <br />furrows are installed, they may have cross dikes, as appropriate, to prevent water from concernrating at <br />a low section and causing a failure. Spacing between furrows will depend on the slope and the prox- <br />imity to the top of the reclaimed sideslope. <br />Table 3.6-13 shows the typical minimum standards to be used in designing diversion ditches for <br />reclaimed areas only. There are other ditch design standards in the permit for other areas, such as <br />roads. Diversion ditch configuration will not inhibit wildlife or livestock travel. Moreover, diversion <br />ditches will be stabilized by seeding a CMLRD-approved perennial seed mix. Table 3.6-13 shows <br />25-toot, 50-foot, and 100-foot vertical spacing design criteria. In using this table, two points need <br />clarification. The designs are examples of minimum standards. Trapper may choose to over-design to <br />compensate for effects of snow, for example. Also, 25-foot, 50-foot and 100-foot spacing may not <br />ahvays be appropriate. However, revised designs will employ the same general criteria as was used to <br />construct Table 3.6-13. Thus, we would not resubmit changes caused by altering vertical spacing. <br />However, other changes would require your approval. <br />• PR-3 -----~- ---.. . <br />3-150a I i REVISIDN APPgRO~JVED ~ <br />I' ~ DATE ~ ~~7 ~/3 <br />l~ .-----~---- l <br />