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~~z • Mr. Brent Page Two October 1, Anderson 1990 • The area along the western boundary adjacent to the undisturbed aspen grove • The entire length of the diversion ditch which runs approximately 100 - 400 feet outside the western and northern disturbance boundary • The entire length of the drainage adjacent to the northern disturbance boundary • The sideslopes adjacent to the temporary access road In the areas inspected, there was no evidence of surficial or mass instability, with no slumps, slides, surface cracking or abnormal drainage observed. Contour furrows were intact and functioning properly to control surface runoff and erosion. Vegetative cover appeared to be well established and vigorous. Minor differences in cover density were noted, possibly due to compaction of the seedbed in the subject areas. In addition to the standing vegetative cover there was evidence over the entire area of development of a surficial cover • of organic material at the ground surface. Inspection of both the undisturbed runoff diversion and the natural drainage paralleling the northern disturbance boundary indicated no significant recent geomorphic changes, with no evidence of abnormal headcutting, downcutting, mass wasting, or sediment deposition. There were several locations where the existing diversion may have overtopped during high flow conditions. There was no evidence of significant down-gradient erosion at these locations. Given the effectiveness of the existing diversion in intercepting and routing overland flow, coupled with channel stability and lack of geomorphic Changes, it is recommended that the diversion be retained. Over the long term, natural processes will result in elimination of the diversion and re- establishment of natural drainage. Certain areas were identified where various factors, including limited vegetative establishment, relatively steep slopes, moderate gradients on contour furrows, and remaining disturbance features have resulted in localized surficial or drainage channel erosion. It should be noted that none of the following sites are considered to have significant erosion problems. Existing erosion is minor after five years of reclamation and remedial measures are recommended solely to insure the long term integrity of the effected areas; 1)t A small area approximately 50 feet x 70 feet on the southeast side of the narrow ridge has limited vegetative establishment. Sheet . runoff has washed sediment from this area into the perimeter ~,;~~ diversion ditch, partially blocking the ditch and causing the ditch `~ at to overflow at this location during high runoff. This area should ~~~z~~.~ be chisel-plowed to alleviate compaction, reseeded and mulched.' ''~ The diversion should be cleaned out and repaired within the affected section of approximately 30 feet.