1. Typical Timber Bulkheads. 



Figure 1 shows a conservatively designed, low bulkhead for instal- 

 lation where the existing grade along the sheet piles is somewhat 

 higher than the low water level. Figure 2 shows an intermediate bulk- 

 head suitable for retaining fill at the site of a marina or for provid- 

 ing a finished waterfront in a housing development. If these bulkheads 

 are located farther inshore, or if the outside water level variations 

 are less than shown in the figures, the heights of bulkheads and 

 lengths of sheet piles may be reduced. 



The anchorage systems (Figures 1 and 2) depend upon the passive 

 resistance of a mound of earth immediately around the anchor post and 

 wales. The theoretical mound required to develop this passive resis- 

 tance is shown by a dotted 'line» If backfill is placed directly against 

 the sheet-pile bulkhead before this mound of earth is placed around the 

 anchor system, the resulting forces may displace the bulkhead or even 

 push it over, resulting in a costly and disastrous failure. After the 

 mound is placed over the anchorage system, backfill can be deposited 

 against the sheet piles by a dragline, truck dumping, hydraulic pipe- 

 lines, or other suitable methods. 



Figure 3 shows a bulkhead suitable for the deepwater parts of 

 marinas, or for locations where the existing water depths are 6 to 8 

 feet and extensive landfills are desirable. The anchorage system 

 (Figure 3) is a self-supporting A-frame that does not depend on passive 

 earth resistance. This anchor system is particularly adaptable to 

 filling by the hydraulic method because the backfill can be raised 

 behind the sheet piles without regard for the placement of backfill at 

 the anchorage location. 



To install the A-frame anchorage, a pile-driving rig is required to 

 drive the piles to specified bearing capacity. At locations with less 

 water level variation than the 4 feet shown, the height of finished 

 grade may be lowered proportionally. For an increase in water level 

 variation, a similar increase in height of finished grade can be made 

 with a corresponding reduction in water depth. The 5-foot vertical 

 distance from finished grade to tie rod level should be maintained. 



2. Construction Procedures. 



The proper sequence for bulkhead construction is: 



(a) Drive all round timber piles, both vertical and bat- 

 tered; set or drive all posts „ 



(b) Using bolts, attach the horizontal wales for the sheet 

 piles and the anchorage system. 



(c) Drive sheet piling. 



