BREAKWATER REHABILITftTION STUDY, CRESCENT 

 CITY HARBOR, CALIFORNIA 



Coastal Model Investigation 



PART I: INTRODUCTION 

 The Prototype 



1. Crescent City Harbor, Calif., is located on the Pacific Coast ap- 

 proximately 17 miles* south of the Oregon-California border (Figure 1). The 

 existing outer breakwater is 4,670-ft long, the main stem is 3,670-ft long, 

 and the easterly extension (dogleg) of the breakwater is 1,000-ft long. Orig- 

 inal project plans intended for the main stem of the breakwater to extend out 

 to an area called Round Rock. However, beyond sta 37+00 the main stem of the 

 original breakwater sustained severe damage and was reconstructed on two occa- 

 sions. Finally, this portion of the main stem was abandoned and the present 



1 ,000-ft-long easterly dogleg was added. 



2. Two-dimensional (2-D) stability tests were conducted on the tetra- 

 pod armor designs proposed for the trunk portion of the 1,000-ft dogleg 

 (Hudson and Jackson 1955, 1956). In 1957, 1,836 25-ton unreinforced tetra- 

 pods were placed on the sea-side slope from sta 41+20 to the end of the dog- 

 leg (sta 46+70), and 140 25-ton unreinforced tetrapods were stockpiled on the 

 sea-side slope of the first 200 ft of the dogleg, adjacent to the main stem 

 (sta 37+00 to 39+00). As of 1975, approximately half of the tetrapods placed 

 between sta 37+00 and 39+00 had broken because of severe wave action at the 

 elbow. In 1974 the stone-armored section, close to sta 37+00 shoreward to 

 about sta 35+00, had deteriorated to the extent that 246 40- to 42-ton unre- 

 inforced dolosse were placed on the sea-side slope of the last 230 ft of the 

 breakwater's main stem (sta 34+70 to 37+00). Various portions of the break- 

 water, including the deteriorated tetrapod area (sta 37+00 to 39+00), were 

 also repaired with armor stone in 1979. 



3. Sea-side slopes of the outer 230 ft of the main stem (sta 34+70 



* A table of factors for converting Non-SI units of measurement to SI 

 (metric) units is presented on page 3. 



