Table 1 - GRADATION OF RIPRAP IN POUNDS | ||
Max. Weight of Stone required (lbs) | Min. and Max. Range in weight of Stones (lbs) | Weight Range 75 percent of Stones (lbs) |
150 | 25 - 150 | 50 - 150 |
200 | 25 - 200 | 50 - 200 |
250 | 25 - 250 | 50 - 250 |
400 | 25 - 400 | 100 - 400 |
600 | 25 - 600 | 150 - 600 |
800 | 25 - 800 | 200 - 800 |
1000 | 50 - 1000 | 250 - 1000 |
1300 | 50 - 1300 | 325 - 1300 |
1600 | 50 - 1600 | 400 - 1600 |
2000 | 75 - 2000 | 600 - 2000 |
2700 | 100 - 2700 | 800 - 2700 |
D75 = 3.5/CK WDS for Channel Banks
where: D75 = Size of the rock at seventy five percent (75%) is finer in gradation, in inches.
W = Specific weight of water, usually 62.4 Ibs./cu.ft. |
D = Depth of flow in stream, in feet in flood stage |
S = Channel slope or gradient, in ft/ft. |
C = A coefficient relating to curvature in the stream |
K = A coefficient relating to steepness of bank slopes |
CR/WSW | C |
4 - 6 | 0.60 |
6 - 9 | 0.75 |
9 - 12 | 0.90 |
Straight Channel | 1.00 |
Bankslope | K |
1.5:1 | 0.50 |
1.75:1 | 0.63 |
2.0:1 | 0.72 |
2.5:1 | 0.80 |
3.0:1 | 0.87 |
Idaho Admin. Code r. 37.03.07.057