figure 7-27. - Extensive concrete encasement of wood pile.

Figure 2-28. - Fender pile repair.

extend to a minimum of 3 feet below the top of the deteriorated wood sheeting. The fill at the inside edge of the old bulkhead is normally removed before driving the new sheetpiling. When this is done, a concrete cap should be placed over the new sheeting to form a seal with the existing construction.

Dolphins

Maintenance of dolphins includes the replacement of fastenings and any wire rope wrapping that has become ineffective through corrosion or wear. If dolphins are connected by a catwalk, maintenance of the catwalk includes the replacement of damaged or deteriorated timbers or the cleaning and painting or the replacement of the steel members. Repairs of dolphins include replacement of piles, wire rope wrappings, and blocking. If any piles have to be replaced, the fastenings should be removed only as far as necessary to release the piles that are damaged. Care should be taken to drive the new piles at the proper angle so they will not have to be "pulled" too far to fit them in place. The size of piles to be replaced should be carefully noted, particularly at the head or intermediate point where they are fitted together with the other piles. Much trouble in cutting and fitting the replacement piles can be avoided by selecting piles with the proper size head. All replacement piles should be driven before any are brought together. After all are driven, the center cluster should be brought together first and should be fitted, chocked, bolted, and pinned; they are then wrapped with wire rope. All cuts in piles for fittings, bolts, and wrappings should be thoroughly field-treated with creosote. Frequently, it is more economical to build a new dolphin, rather than to repair an existing one.

STONE, MASONRY, AND EARTH STRUCTURES

Some structures, such as breakwaters and seawalls, depend upon their mass for stability against wave action and currents. Materials commonly used for such structures are stone, blocks of concrete, cast-in-place concrete, and earth. Earth structures are usually converted with a protective coating, such as riprap, to hold them in place.

The most common cause of deterioration and damage to mass structures is wave action particularly during storm conditions. Severe wave action may move stones out of place when built into a wall or move others by washing out sections of a breakwater or causeway. This damage makes the structure more susceptible to additional damage. Repairs should be made as soon as possible.

Stone Structures

Stone structures are considered to be those constructed of stone, blocks of concrete, or special concrete shapes, such as tetrahedrons, piled up or distributed in a random fashion. Some structures may have an earth core retained in place by stone,