Using this method, Herbich (1981) has developed a series of charts which can 

 be used to estimate bottom scour for various combinations of sediment size, 

 bottom current velocity, and pipeline diameter. Similar calculations have 

 been performed to produce Figure 18 below, which is typical of those found in 

 Herbich (1981) . Use of this figure is illustrated in example 5 below. 

 Example 5. For the following given initial design conditions, calculate 

 maximum pipeline scour depth. 



d g = 0.0082 ft 



H = 6.0 ft 



T =7.0 sec 



R - 1.0 ft - pipe outside radius 



u = current velocity at top of pipeline, 



2.0 ft/sec based on field measurements 



Solution: Simply enter Figure 18 on the horizontal axis at u = 2.0 ft and 

 locate the curve for the 24 -in. outside diameter. Then read maximum scour 

 depth, S max , from the vertical axis to be 2.5 ft. 



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