Laserfiche WebLink
' <br /> Table 5-5 <br />' ~ RIPRAP REQUIREMENTS FOR CHANNEL LININGS ** <br /> -1)0.66* <br />VS0,17/(S Rock Type *** <br /> s <br /> _(ft}/sec) <br /> 1.4 to 3.2 VL <br /> 3.3 to 3.9 L <br /> 4.0 to 4,5 M <br />4.6 to 5.5 H <br />5.6 to 6.4 VH <br />1 <br />* Use Ss = 2.5 unless the source of rock and its densities are <br />' known at the time of design. <br />** Table valid only for Froude number of 0.8 or less and side <br />' slopes no steeper than 2h:]v. <br />*** Type VL and L riprap shall be buried after placement to <br />reduce vandalism. <br />SM9 slope mattress with toe protection may be substituted <br />for Type VL or L riprap. <br />G12 gabion with toe protection may be substituted for Type M <br />and Type H riprap. - _ <br /> 5'.4.3 Toe Protection <br />Wh <br />l <br />l <br /> ere on <br />y the channel sides are to be lined, additiona <br />riprap <br /> is needed to provide for long term stability of the lining. In this <br /> case, the riprap blanket should extend at least 3 feet below the <br /> existing channel bed and the thickness of the blanket below the <br />' existing channel bed increased to at least 3 times d50 to accommodate <br /> possible channel scour during floods (see Figure 5-4a), For sandy <br />' soils, consult specific criteria for channels an sandy soils. If wire <br /> enclosed rock lining is used, the toe must be protected by placing <br />' riprap at the toe. This is needed to protect against frequently <br /> occurring abrasion, (see Figure 5-4b and 5-4c). <br /> <br /> 5-1-84 <br />1 <br />