Table 2 



Humboldt Bay Jetties 



Humboldt Harbor and Bay, California 



Date(s) Construction and Rehabilitation History 



1889- The initial construction of the north and south jetties was com- 

 1899 pleted at the site (Figure 6) during this time frame. The south 

 jetty was 4,000 ft long with a +10-ft mllw crest el. The ocean- 

 side slope was IV: 2.65H, and the channel-side slope was 1V:2.25H. 

 The north jetty was constructed to a length of 1,500 ft with a 

 crest el of +12 ft mllw. The ocean-side slope was 1V:2.42H, and 

 the channel-side slope was 1V:1.85H. Stones used in the jetties 

 were composed of rock up to 8 tons in weight. The jetties termi- 

 nated at approximately the 18-ft contour. 



1900- During this period the jetties deteriorated from lack of mainte- 

 1907 nance. The channel shoaled, and by 1907 the outer ends of the 



jetties were completely buried in the sand of the uncontrolled bar. 



191 1- Reconstruction of the south jetty was in progress. Structure de- 

 1915 sign consisted of 1V:2H side slopes with crest el ranging from 



+14.8 ft to +19 ft mllw. Class I stones (10 to 20 tons) were used 

 for facing the sea-side slope of the outer 2,400 ft of the jetty; 

 Class II stones (1 to 10 tons) made up the main part of the jetty; 

 and Class III stones (3 to 500 lb) were used to level off the top 

 and fill in the voids between the larger stones. A 2-ft-thick, 

 20-ft-wide concrete slab was placed on the crown. 



1915 Reconstruction of the north jetty was completed. The jetty was re- 

 constructed with 1V:1.5H side slopes with the following classes of 

 stones: Class I rocks ranged from 6 to 20 tons averaging at least 

 10 tons; Class II stones ranged from 500 lb to 6 tons and averaged 

 at least 1 ton; and Class III rocks ranged from 3 to 500 lb. Most 

 of the Class III stones were used at the shoreward end of the 

 structure, the proportion decreasing as the jetty approached its 

 outer end. Class III rocks were used for the jetty core, Class II 

 for the enrockment over the core, and Class I as a facing for the 

 side slopes, the larger pieces being used on the exposed side of 

 the jetty. The top was leveled off and all voids filled with small 

 stones. The structure then was capped with a 2-ft-thick, 20-ft- 

 wide concrete slab. 



1925- The north and south jetties were completed to their present lengths 

 1927 (north jetty, 4,500 ft; south jetty, 5,100 ft). The side slopes of 

 the jetties were approximately 1V:1.5H (Figure 6) with a crest 

 width of 20 ft. The el of the crest varied from about 12 to 19 ft 

 mllw at the seaward end. Parapet walls and concrete caps were in- 

 cluded on both jetties, and mass concrete was poured on channel- 

 side slopes to stabilize armor stone. The parapet walls were loca- 

 ted on the south sides of the jetties and were about 4 ft high and 

 6 ft wide. 



(Continued) 

 16 



