Table 30 



Tillamook Bay 



Tillamook, Oregon 



Date(3) Construction and Rehabilitation History 



1912 The north Jetty was authorized to 5,700 ft. 



1914- The north Jetty was constructed to 5,400 ft using 428,672 tons of 

 1917 rock. 



1921 The north Jetty was repaired with 500 tons of rock placed near the 

 shore end of the structure. 



I93I- The north Jetty was reconstructed and extended to the full authorized 

 1933 length of 5,700 ft, requiring 320,350 tons of rock. 



1946 Minor repairs were made to the shore end of the north Jetty. 



1955 Repairs were made to the north Jetty near the shore end. Also, a 



breach at the beachline of the north Jetty that had been cut to bring 

 a beached vessel through the Jetty was repaired. Repair work used 

 5,535 tons of rock. A 1955 aerial photograph of the north Jetty is 

 given in Figure 62. 



1962 The beach was built up on the north side of the Jetty for 3,500 ft. 

 Seaward of the beachline, the Jetty crest was at half tide and the 

 outer 800 ft was below the low water level. 



1963- The north Jetty was rehabilitated. The Jetty was raised to a crest 

 1965 elevation of +18 ft mllw from sta 32+60 to 53+00 then increased to 

 +24 ft mllw between sta 53+00 and 55+00, and remaining at +24 ft to 

 sta 57+00. Design wave for the rehabilitation varied from a l6.5-ft 

 breaking wave nearshore to a 23.5-ft breaking wave at the head. The 

 work required an estimated 174,000 tons of class "A", "B", and "C" 

 stone, plus 60,000 tons of select class "A" stone. Select class "A" 

 had a minimum weight of 18 tons, class "A" had a minimum weight of 

 12 tons and an average weight of 15 tons, and class "B" had a minimum 

 weight of 5 tons and an average weight of 8 tons. At least 57 per- 

 cent of the weight was class "A". 



1965 The south Jetty was authorized to 8,000 ft. 



1969- The south Jetty was constructed to 3,695 ft. The contract was for 

 1971 construction of the first 5,000 ft of the Jetty, but overruns caused 

 by scour in front of the construction caused the work to be sus- 

 pended. The work required 655,049 tons of stone. 



1972- The south Jetty was extended by 2,830 ft, requiring 783,944 tons of 

 1974 stone. The distance between the north and south Jetties was reduced 

 from 1,400 ft to 1,200 ft. 



(Continued) 



133 



