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f <br />'k: <br />u <br />% <br />k.- <br />elude; Bidim-C-22 (Monsanto); Typar 3401 (Dupont); Poly- <br />filter-X (Carthage Mills); and Mirafi 140 (Celanese). <br />Rock sizes should be well mixed. Approximately one~ <br />half of the rock should be 12 inches in diameter. The <br />remainder should be used to fill in the spaces between <br />^^0 pj0viously placed rock and should consist of both <br />large and small rocks. The minimum recommended thickness <br />of riprap is approximately 12 inches. <br />Riprap placement may include toe and end protectionr <br />particularly in controlling stream bank erosion. Toe and <br />end protection is accomplished by placing the largest <br />rocks and the thickest portion of the riprap in position <br />as shown in Figures A~2 and A~3. In some instances# ex“ <br />cavation may be required to provide sufficient depth of <br />toe and end protection. If mechanized excavation is nec­ <br />essary# a permit is required. <br />(•THIS DOES NOT CONSTITUTE ENDORSEMENT OF THESE BRANDS.) <br />MAINTENANCE REQUIREMENTS <br />All riprap shore protection requires maintenance. <br />Proper filter blanket thickness, rock size# placement# <br />and slope will prevent frequent maintenance. All riprap# <br />however# will experience some displacement. The desired <br />slope# thickness# and the filling of holes in the rock <br />surface should be restored when needed. <br />ADDITIONAL INFORMATION <br />If you desire additional information on shore protec­ <br />tion# a pamphlet# "Help Yourself"# is available from the <br />U.S. Army Corps of Engineers. The pamphlet discusses <br />critical erosion problems on the Great Lakes and cites <br />additional methods of shore protection. Address your re­ <br />quest to: <br />O.S. Army Corps of Engineers <br />1210 U.S. Post Office and Custom House <br />St. Paul# Minnesota 55101 <br />1-612-725-7506 <br />Reminder: Any riprap shore protection project which <br />does not conform to the aforementioned criteria must be <br />authorized prior to installation by a permit from the De­ <br />partment of Natural Resources pursuant to Minnesota Stat­ <br />utes# Section 105.41 and 6 MCAR __ 1.5021 C. <br />iI <br />■ <br />1 <br />i <br />V <br />B <br />■ <br />K <br />■ <br />m <br />■ <br />- ---