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• site aze considerably more resistant to scour than the materials found on the Soutlr Platte. Taking the above factors into account, I would recommend that the requirements found in the guidelines regarding minimum berm top widths could be reduced by 25% for application at the St. Vrain mining site and still be considered conservative (large: margin of safety). The minimum berm top widths are intended to provide sufficient width to prevent failure of the berm due to scour and/or head-cutting during a flood event. Please note that the guidelines define "beans" to be areas of native material separating ~i river or stream from the overbank gravel pits, or one overbank gravel pit from another overbank gravel pit. The term "berm top width" used in the guidelines is essentially the distance from the top of the stream bank to the top of the gravel pit bank, or the distance t~etween the top of the banks of adjacent pits. In this report, and with respect to the proposed mining and reclamation plan, this distance is considered to be the recommended setback distance of the top of the gravel pit excavation to the top of the St. Vrain Creek streambank. The 25% reduction of the required berm top widths (setback distance) is the only recommended modifications to the UDFCD guidelines. All other guideline requirements regarding sizing of rip-rap rock, extents of protection, etc. are recommended to be followed. Riverbank Protection • The south banks and overbank areas of the St. Vrain Creek adjacent to the proposed mining site are generally gently sloped, well vegetated, and do not appear to be experiencing ongoing bank erosion. Therefore, riverbank protection work or stat~ilization is not required nor recommended as part of the proposed mining and reclamation plan. Pitside Bank Protection The perimeter slopes of reclaimed gravel pits require additional erosion protection beyond revegetation if the embankment separating the pit from the creek is to be: protected from loss during large flood events. Protection of the pitside banks permits reduction of the required setback distance of the top of the pit bank from the top of the streambank. The UDFCD guidelines recommend that neither riverbank or pitside bank protection is necessary if the distance separating the pit from the river is at least 400 feet wide. For the proposed mine site this distance will be reduced 25% to 300 feet as discussed above. If pitside bank protection as specified by the guidelines is provided, the setback distance may be reduced to a minimum of 225 feet (a 25% reduction of the guidelines 300 ft. distance). Therefore, at no point should the top of a mining pit bank be closer than 225 feet to the top of the south bank of the St. Vrain Creek. A distance of 300 feet however, is preferred since no pitside bank protection would be required in that case. As currently shown on the map titled "Reclamation Contours" (Exhibit F-3, Sheet 8 of • 12) of the submitted Mining and Reclamation Plan, riverside setback distances of less than 250 feet aze currently proposed for two locations in Phase II (East Plant), and one 6