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' ~ •.:.. <br />• INFORMATION YOU SHOULD KN(I~i.EEFCRE PLANNING YOUR ROCK RIPRAP PROJECT <br />~ You should first evaluate the extent of bank cutting and the damages"that map <br />I occur if corrective measures are not provided. Then consider the economics <br />;~°,~ o£ installing streambank protection. <br />~ '"w <br />~ Obtain the services of a qualified technician in planning your streambank pro- <br />tection project. <br />Rock tiptop is a permanent type of bank protection. Temporary materials such <br />as anchored trees, brush, and willow mats can be used successfully in some <br />cases, but their length of life is 1 united and they are subject to damage and <br />failure . <br />Rock riprap has been used widely by faun oxners as well as government agencies <br />for streambank control. <br />In most locations the streambed moves or shit is during periods of storm flow. <br />To protect your proposed rock revetment from undercutting during storm periods <br />a toe section excavated to firm material should be planned. <br />A rg oval blanket between the large rock of the revetment and the soil bank <br />should be included in your plan. This blanket will provide a filter to pre- <br />vent removal of soil particles through the rock. This condition which can <br />cause failure is most serious after periods of high water when the soil is <br />draining rapidly toward the stream, <br />To prevent washouts at upstream and downstream locations plan to extend your <br />revetment beyond the curved portion of the streambank. Tie in both ends o£ <br />+,.. <br />your riprap to natural barriers or by placement of extra rock. <br />You will be able to use the least amount of mck by shaping the streambank to <br />the planned slope of the rock riprap. Evaluate the cost of sloping and shap- <br />ing for placing a uniform thickness of rock as shown in the sketch below <br />against the cost of larger volmnes of rock required when the banks are not <br />shaped. <br />Es fisting streambank may be removed <br />or move slope toward channel and fill ~~ <br />with streambed material ~ <br />Notc: place stone having miniuaun <br />diameter of 24"' in toe excavation <br />15"~ Min. <br />r~ Streambed <br />I <br />,\ `~ Placed streambed <br />gravel or earth fill <br />3' Min. <br />_;~ ~ 24" Min. ~ <br />3'"Min.' \~~, Gravel 6lonket on earth slope. <br />Minimum thickness 4". Not <br />187 steeper than 1 to 1 <br />