Construction began on the old breakwater in 1828, following the design of William 

 Strickland of Philadelphia and under the general administration of the Quartermaster 

 General, and the technical direction of the Corps of Engineers. Work continued 

 intermittently, depending on need, engineering know-how, and congressional appropria- 

 tions. The inner breakwater, consisting of the old breakwater and ice breaker (completed in 

 1869), and tlie Gap (completed in 1897), formed Breakwater Harbor; the outer breakwater 

 completed in 1901, formed the Harbor of Refuge. 



During construction, stone sizes were varied to reach a satisfactory size. Specifications in 

 1828, first called for stones from 200 pounds to 2 tons, but was changed to a 500-pound 

 minimum requirement. Soundings in 1830 indicated a general lowering of the structure 

 "due to wave and tidal action." Further study was undertaken and the size specification 

 revised to 2.25 to 6 tons. Later, stones up to 13 tons were used for tlie upper parts of the 

 outer breakwater. 



By the time design was being undertaken for the outer breakwater, and when the 

 Breakwater Harbor was no longer adequate for the larger, deeper-draft ships, two important 

 changes had taken place: (1) design was now more closely following engineering principles 

 rather than intuition; and (2) construction equipment had now developed to where larger 

 stones could be handled, and precise placing was possible. This permitted certain 

 improvements over the design of earUer sections, although the seaward slope of the existing 

 structure, considered as having gradually settled to a stable position, was maintained in the 

 new design. The height was Umited to dissipate the wave forces, without the full impact 

 being absorbed by the structure, and the step arrangement of the top section tended to 

 reduce the scour effect at the toe. 



The criteria finally developed for the Delaware Bay work were used as a basis for the 

 Sandy Bay breakwater in Massachusetts and the San Pedro breakwater in California. The 

 simplicity of construction and repair of these breakwaters seemed to outweigh the problem 

 of the massive foundation required for such a structure. 



Different aspects and the relation of various stages of construction from some of the 

 engineering drawings and photographs are shown in Figures 28 through 33 . 

 (7) Structural Performance. 



(a) Performance. The outer breakwater (Harbor of Refuge), and the inner 

 breakwater (Breakwater Harbor), have both performed exceptionally well, considering their 

 long span of service. Harbor of Refuge, with depths from 15 to 70 feet, affords good 

 protection from the easterly gales; Breakwater Harbor, with depths up to 10 feet is excellent 

 in all weather including the heavy northwesterly gales (U.S. Department of Commerce, 

 1966). 



Records indicate that Breakwater Harbor, more useful in the days of sailing ships, often 

 .provided shelter to more than 200 ships at a time. 



54 



