Figure 34. Grout-filled cloth mattress bank protection with weep holes 

 (Courtesy of Construction Techniques, Inc.). 



In limited spaces, a composite type of bank protection may be used, with a sheet-pile or 

 a poured-in-place concrete wall at the top and a revetted slope from the toe of the wall to 

 the channel bottom. The least costly combination is usually a poured-in-place L-wall with 

 footing at about water table level (Fig. 28). The revetted slope should just cover the toe 

 projection of the footing and extend downward on as steep a slope as the material will 

 safely stand, considering the surcharge loading of the wall and the material it retains. The 

 wall should be provided either with weep holes and a French drain just above the footing 

 slab, or with continuous drainage from the backface of the wall, under the footing slab, to 

 the revetment filter layer. If sheet piling is used, the joints will usually be permeable enough 

 to reUeve hydrostatic pressures without weep holes. The design of the wall part of a 

 composite section generally follows the design of an ordinary bulkhead or retaining wall; 

 several versions are covered in Chancy (1961) and various general engineering texts. 



e. Riverfront Protection. To berth boats directly in a river, several means are available 

 for providing some protection to the berthing area. A current deflector placed upstream will 

 divert the main force of the river current away from the area and prevent floating debris and 

 ice floes from impinging at fuU' current speed on the berths and boats. The deflector is 

 usually built like a pile-dike fence inclined downstream, with heavy beams for horizontal 

 members in the area of surface level fluctuations to fend off floating debris. Enough current 



72 



