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All jetties will be constructed of Type H riprap (USDCM class- <br />ification) and toed into the existing riverbed a minimum of 5 <br />feet. The core of the jetties may be constructed from a mix- <br />ture of concrete rubble with no exposed rebar and soils. How- <br />ever, the surface of the jetty must be Type H cock. Banks <br />between jetties are to be revegetated in accordance with the <br />requirements of Section 2.2.1 - Revegetation of River Banks. <br />2.4 PITSIDE BANK PROTECTION <br />The interior banks of reclaimed gravel pits require additional erosion <br />protection beyond revegetation if the berm is to be protected from <br />loss during large flood events. Protection of the pitside banks per- <br />mits the reduction of top width of the berm provided it is accomp- <br />lished using the requirements specified in the next five subsections. <br />Construction of the pitside bank protection will occur coincidentally <br />with the construction of river bank erosion protection measures. That <br />is, when mining activities abut against a river or stream, erosion <br />protection of both the river bank and the pitside bank must be under- <br />taken. In areas experiencing ongoing bank erosion as determined by <br />District, it may be necessary to provide river bank protection prior <br />to the commencement of mining operations, however, it will not be <br />necessary to construct pitside bank protection measures until such <br />time as gravel extraction is completed. <br />2.4.1 Riprap <br />When riprap is used to stabilize the pitside slope, the rock <br />shall be placed at a slope no steeper than 2.5x:1v. Riprap <br />sizing will be in accordance with the safety factor method. <br />The minimum safety factor shall be 1.25. <br />SF = Cos 0 tan ~ <br />n tan + sin 0 <br />UDSFCD GRAVEL GUIDELINES 12/17/87 <br />2-13 <br />