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0 <br />• <br />3.6.3.6 Erosion Control <br />It is improbable that all rills and gullies in excess of nine inches can be fully prevented on areas <br />reclaimed to rangelands. Adjacent undisturbed rangelands currenty have rills and gullies, some of <br />which are in excess of ten feet in depth. Figure 3.6-6 is a picture of one such gully in an undisturbed <br />drainage near the proposed mine plan area. Gullying on rangelands inhibits its use when forage pro- <br />duction or travel by livestock is adversely affected. This condition is related to both gulf/ shape and <br />depth. <br />Erosion control of reclaimed rangelands logicaly falls into two major categories, topographic <br />sideslopes, and drainageways and associated tributaries. Erosion control in drainageways is dis- <br />cussed in Section 4.8.1.3. <br />Gullying on sideslopes of reclaimed lands results from two sources. Where flows are concentrated due <br />to mining activities, such as breaks in diversion ditches, drainage off roads, pads, material piles, etc., <br />gullying, to some degree, may be induced. The second cause of gullies on reclaimed sideslopes is <br />from the concentration of sheet flow across the hillsides. This type of gully producing phenomenon is <br />most likely to occur in the first two years following topsoil replacement and perennial seeding. With <br />each passing year after perennial seeding and establishment, the potential for gullying due to sheet <br />erosion quickly diminishes. By approximately the third year, a point is reached whereby sheet flows are <br />reduced sufficiently that natural healing of the gully occurs. <br />The two types of sideslope gully formation require two different methods of control or repair. Where <br />gullies deeper than nine inches are the result of concentrated flows due to mining activities, Trapper will <br />attempt to eliminate or control the source of the concentrated flow which produced the gully. Also, the <br />gully will be graded -in and reseeded to the approved seed mix. These types of repairs will be per- <br />formed during the summer and early fall after formation of gully. The work will be completed by <br />November 15, annually. <br />PR -3 <br />3-150 !' REVISION APP OV D <br />11 DATE ' 43 <br />