Section 37.03.07.064 - CONCRETE PLANK BOAT LAUNCH RAMPS01.Construction of Concrete Plank Boat Launch Ramps. Concrete plank boat launch ramps, shall be constructed with individual sections of precast, reinforced concrete planks linked together to provide a stable non-erosive water access (see Figure 20, APPENDIX K, located at the end of this chapter).02.Construction of Concrete Planks. Typical concrete plank size is twelve feet by fourteen inches by four inches (12' x 14" x 4"). All planks shall be constructed with Type II low alkali cement. All planks shall have a broom form finish, free of rock pockets and loose materials. Figures 21 and 22 shows a typical launch plank detail. (See APPENDIXES L and M).03.Assembly of Planks. The planks shall be assembled out of the water and slid into place on a constructed launch ramp where water velocities do not exceed two (2) feet per second. In waters exceeding (2) feet per second the ramp sections shall be linked together and fastened to pre-positioned stringers anchored into the launch ramp. (See Figure 23, APPENDIX N, located at the end of this chapter).04.Water Depth. The water depth above the lower end of the ramp section shall not be less than three (3) feet during low level or low flow periods. (See Figure 20, APPENDIX K, located at the end of this chapter).05.Construction of Boat Ramp. The boat launch ramp shall have a base constructed of sound, dense, durable, angular rock resistant to weathering and free from soil, shale and organic materials. Rounded cobbles, boulders and streambed material are not acceptable as base material in areas with stream flow velocities greater than two (2) fps. Base materials shall be covered with a layer of (three-fourths inches (3/4") min.) crushed rock with a minimum depth of two inches (2"). The ramp shall have a minimum and maximum slope of ten percent (10%) and fifteen percent (15%) respectively, and shall be constructed in a manner to avoid long incursions into the stream channel. All ramps and fill material shall be protected with rock riprap in accordance with Rule 057 when stream flow velocities exceed two (2) fps. (See Figure 24, APPENDIX O, located at the end of this chapter).Idaho Admin. Code r. 37.03.07.064