utilities in the land areas of marinas is similar to a land-based enterprise. Maintenance of 

 basins, channels, piers, docks, perimeter structures, and protective works is different from 

 landside maintenance and warrants the following remarks: 



(1) Breakwaters and jetties are frequently maintained by the U.S. Army, Corps of 

 Engineers or the State. If maintenance is a local responsibility, detection of any early signs 

 of deterioration is important. Excessive toe scour of a structure in a high-wave energy 

 environment should be corrected by filling the scour pockets with stone of adequate size 

 before the integrity of the structure is jeopardized. Steel structures usually deteriorate as a 

 result of corrosion unless their coatings are maintained or their cathodic -protection system 

 are kept in working order. Abrasion near the sand line is also a possibility, but prevention is 

 difficult. Cladding with concrete is a method by which steel abrasion has been successfully 

 prevented. Concrete structures usually deteriorate as a result of progressive cracking and 

 spalling. Major damage can often be prevented by pressure-grouting the cracks with an 

 epoxy cement. This process requires the equipment and skiUs of a concrete repair specialist. 

 Timber structures usually deteriorate rapidly if connectors loosen and begin to work and 

 flex under wave agitation. Periodic tightening of nuts may prolong the hfe of a timber 

 structure. Leaching of pressure-injected preservatives will expose the timber to marine-borer 

 attack or dry rot. Cladding with concrete has prolonged the Ufe of some timber structures. 

 Various synthetic membrane wrappings have been used for protection of timber piles, often 

 with considerable success. 



(2) Armored perimeter slopes usually fail either by plastic flow or shding of the 

 embankment after a rapid water level drop or by having the fines pumped through voids in 

 the armor as a result of an inadequate filter. Several types of corrective action may be taken 

 depending on the type and severity of the failure. Trenching and installation of drains 

 behind the slope may solve a sloughing tendency in clayey soil. Grout-seaUng a leaking 

 riprap may prevent further pumpout of fines. If a riprap deteriorates under prevailing wave 

 and current action even though the filter remains effective, it may either be grouted with 

 concrete or stabilized by the replacement of an additional layer of heavier stone. 



(3) Vertical bulkhead walls frequently fail because of inadequate depth of penetration 

 of sheet piling or improper filtering of soils under and behind a poured-in-place concrete 

 waU. Saturation of the retained fill coupled with pulsations in the hydrostatic head 

 differential due to wave action results in the fiU being pumped out from under the wall. This 

 action can sometimes be stopped by filling the sinkholes behind the wall with a mixture of 

 straw and gravel or quarry waste, which eventually clogs the leak and effects a filtering 

 action. If this corrective action fails, it may be necessary to excavate a wide trench behind 

 the wall to the depth of the mud line at the face of the wall and place a layer of filter stone 

 in the bottom of the trench before backfilUng. 



If the leakage of fines is through joints between concrete or timber sheet piles, seaUng of 

 the joints may be possible. One method is to drive about a 3-inch pipe between the wall and 



245 



