_INSPECTION - C1994082 (77) - Laserfiche WebLink

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• Active rills were evident in various fenced shrub establishment area locations, including the northern RMRS weed fabric plots, within SP07-1. Low impact manual stabilization measures should be employed as necessary in these locations to curtail erosion without causing collateral damage to shrubs and experimental plots. • Various other locations as noted on 2009 Rill and Gully Map. Permanent Channel Erosion Channel erosion that will require repairs this year in accordance with the approved rill and gully plan was noted in several locations, as listed below. • In the Pond 11A watershed, steep riprap segments along the upper portion of Permanent Channel YPM-13 have blown out and eroded; substantial repairs necessary. Also, two erosion control ditches that feed into Permanent Channel YPM-9 have eroded; require repair and TRM installation or other measures to prevent recurrence. • Side-cutting erosion and gully erosion parallel to upper YPM-6-1, a short distance downstream from the YPM 19 confluence. • Along the steep lower TRM segment of YPM-6-1, flow has scoured beneath the TRM and repairs are necessary; large riprap may be warranted through this steep segment. • Repairs are warranted in various permanent channel segments in lower portions of the Pond 12 watershed, as marked on the 2009 Rill and Gully Map and/or noted in recent inspection reports. • Minor repairs and additional TRM installation warranted along YPM-8 and adjacent steep slope areas. This location eroded severely last spring; held up much better this year but maintenance is necessary. • Head-cut erosion in riprap Channel YPM-3-2, approximately 80 yards downstream of Shrub Area SP06- 3, with intermittent side-cutting and scour for approximately 50 yards downstream of the head-cut. • An unnamed tributary feeds into YPM-14 approximately 200 yards downstream of Shrub Plot SP05-1, on a relatively level bench location. The tributary channel has eroded and stabilization measures are necessary. • There has been side-cutting erosion along the steep riprapped segment of YPM-14, between the flat bench and the confluence with YPM-3-2, and repairs are necessary. • The Pond 14 inlet segment of YPM-3-2A requires minor maintenance. Various other channel locations are marked for repair on the 2009 Rill and Gully Map, including sections along YPM-24, and the ranch road crossing of the Dragline Deadhead Channel. The Deadhead Channel could not be accessed during the inspection due to extremely muddy conditions of the ranch road. YPM-24 was not walked, because of muddy conditions and the fact that planned repairs had not yet been implemented (operator prudently awaiting better ground conditions before attempting equipment work). The steep channel between Pond 11A and Pond 11 (YPM-12)was walked. The channel has held up well since completion of remedial grading and check dam installations several years ago. There are a couple segments of recent minor erosion that should be monitored, but it would appear at this point that the damage caused by re-disturbance would likely outweigh the potential benefits of further grading or structure installation. Topsoil Topsoiling operations have been largely completed at Yoast, with the exception of future reclamation of the Pond 12 slide and adjacent areas, and reclamation of remaining temporary roads, ponds, and miscellaneous maintenance projects. One additional area that will require topsoiling this year is an approximately 2 acre steep slope site along a former haulroad corridor. The site is located between two large undisturbed habitat patches immediately to the east of drainage YPM-6-1 and south of drainage YPM-7A. No topsoil was salvaged from the location originally, due to an approved salvage variance for the steep soil map unit X8F (slopes steeper than 45%). The slope was regraded and seeded several years ago, but was not topsoiled, and vegetation establishment has been very poor(primarily annual weeds to date). Based on review of the approved permit and applicable regulations, it was determined that the topsoil variance applied only to salvage, not to replacement. Remedial options were discussed with the operator, and it was determined that some regrading would be performed to reduce slope gradient to the extent practicable without causing additional disturbance, to be followed by topsoil replacement and seedbed roughening by dozer, cover crop seeding for initial stabilization, and seeding of the permanent seedmix in the fall. 5