(c) Determine depth of sheet pile penetration and pull in 

 the tie rods. 



(d) Compute bending moment in sheet piling. 



(e3 Determine required thickness of sheet piling. 



(f) Determine size and spacing of tie rods. 



(g) Determine bending moment and required size of wales, 

 (h) Design anchorage to resist for tie-rod pull. 



a. Basic Information . 



(1) Water Depth Required . The depth of water against the face 

 of a timber bulkhead must be determined before the bulkhead can be 

 designed. If the bulkhead is simply a "retaining wall" for shore pro- 

 tection of a building site, the depth of water may be whatever naturally 

 results when the bulkhead is constructed along the desired shoreline. 

 Elsewhere, the depth of water may depend upon the types of boats that may 

 be brought adjacent to the bulkhead (e.g., in a marina). In the latter 

 case, the property owner or the developer of the marina may establish 

 minimum requirements for water depth. Some dredging may be required to 

 achieve these depths, although, generally, the least costly solution is 

 to place the bulkhead farther from shore in deeper water. 



(2) Water Level Variation . At coastal locations, the water 

 level variation on the exposed face of the sheet piling may be obtained 

 from tide tables published by the National Oceanic and Atmospheric 

 Administration (NOAA) , National Ocean Survey (NOS) . At inland loca- 

 tions adjacent to lakes and rivers, seasonal records of high and low 

 water levels may be used. These latter data are available from Corps 

 of Engineers Divisions or Districts, State or local conservation 

 agencies, city or county engineers, and building officials. 



The "design value" used for the high water level requires some 

 judgment. This value need not be the highest water level ever recorded 

 in the vicinity, but should be a reasonably high value that, statisti- 

 cally, is expected to occur within the design life of the structure. 



(3) Depth of Scour . The construction of a bulkhead may deflect 

 wave energy in such a way that it erodes the bottom material adjacent 



to the sheet piling. This is most likely to occur in shallow depths, 

 especially if mean low water (MLW) is less than !■ feet. It is advis- 

 able to assume that the energy deflection, occurring at the time of 

 intermediate and higher tide stages, will erode the bottom material to 

 a depth of 2 or 3 feet below MLW. Accordingly, when lacking more 

 definitive data, assume a minimum low water depth of 2 to 3 feet. This 

 will result in a requirement for slightly longer sheet piling, but will 



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