of a sea wall. The bonds were to be retired with proceeds derived 

 from local and state gasoline taxes. 



The 25-inile-long sea wall in Harrison County, and probably the 

 longest continuous sea wall in the world of ar^r one modern design, 

 was constructed during the period 1925-28 at a cost of $3,U00,000, 

 The design selected by engineers employed by the local government 

 consisted of a reinforced concrete stepped-type slab supported at the 

 toe by a continuous concrete sheet pile curtain wall and at the rear 

 by square concrete bearing piles. The sheet-pile curtain wall is of 

 particular interest since much of the trouble experienced in maintain** 

 ing the Harrison County sea wall was apparently due to construction 

 difficulties with respect to that feature. The sheet piles are 37 

 inches wide, 7 inches thick, and 10 feet long, and extend 8 feet below 

 mean sea level. The bottom third of each pile*s length was of tongue- 

 and-groove design to facilitate guiding during the jetting operation. 

 The top two-thirds of each pile's section was designed in such a manner 

 that grooves in adjacent piles would abut each other. These grooves 

 were later filled with grout to make a solid impervious core and seal 

 the joint. Although theoretically suitable for the purpose, the 

 workmen were unable to drive and grout the piling in such a manner as 

 to obtain a sand-tight curtain wall. As a resiilt, much sand backfill 

 leaked through the curtain wall. Tread elevation of the bottom step 

 is 3 feet above mean sea level and the top elevation of the sea wall 

 is either 8 or 11 feet above mean sea level, the height being governed 

 by the elevation of the backshore area. A concrete sidewalk 5 feet 

 wide originally adjoined the top of the wall throughout its length. 

 Storm drains led from catch basins under the side walk and discharged 

 at the seaward face of the wall. 



The bottom step was built at about the original ground level and 

 a low, narrow beach existed in front of the wall at the time of its 

 original construction. The beach material soon eroded, exposing the 

 ciirtain wall to direct wave action at normal stages of the tide. 

 The loss of sand backfill through openings in the curtain wall, and 

 also through defective Joints in the storm sewers, permitted the ad- 

 Joining sidewalk to settle and disintegrate, and endangered the foun- 

 dation of the parallel Federal highway. However, the unsight]^ con- 

 dition of the sidewalk and lack of backfill which exposed the under- 

 side of the sea wall, and other minor defects, gave observers the 

 impression that the wall was in much worse condition structurally than 

 was actually the case. Other than cracks and crevices, spalling of 

 concrete, stripping of the transverse rib at a number of the expansion 

 Joints, and exposure of reinforcing bars to the corrosive action of 

 sea water, the wall was in relatively good condition, considering its 

 age and lack of maintenance. The exceptionalHy destructive tropical 



