poured on the channel-side slopes to stabilize the armor stone. The parapet walls 

 were typically 1 .2 m (4 ft) high and 1 .8 m (6 ft) wide. 



Numerous repairs occurred on both structures between 1 927 and 1 972. The 

 jetties experienced full breaches as well as extensive damage to both channel- and 

 ocean-side slopes. During the period 1931 to 1932, extensive repairs were made to 

 the jetty heads using precast concrete blocks weighing approximately 14,515 kg 

 (16 tons). The blocks were used to rearmor the heads of the structures as well as 

 provide formwork for future monolith pours. For a time these blocks were used in 

 place of armor stone due to the lack of suitable stone; however, it was soon found 

 that the blocks were easily moved by wave action. 



The south jetty was breached again in 1939 at stas 42+50 and 48+80 and 

 repaired with mass concrete. A partial breach that occurred in the same year on the 

 north jetty, just shoreward of the concrete monolith, also was repaired with mass 

 concrete. In 1950, the south jetty was breached again between stas 85+63 and 

 86+35. It was repaired in 1951 with mass concrete and twelve 90,720-kg (100-ton) 

 concrete blocks. 



In 1957, both structure heads had extensive areas that were void of armor stone 

 as a result of gradual deterioration over a considerable period of time during which 

 no maintenance was performed. Consequently, two to three layers of 13,610- and 

 22,680-kg (15- and 25-ton) tetrapods were used to armor the jetty heads. The tetra- 

 pods placed around the heads had the following characteristics: 



North Jetty 



Seaward of station 73+50 (Channel-side): 22,680-kg (25-ton) 

 tetrapods 1 



Seaward of station 74+10 (Ocean-side): 22,680-kg (25-ton) 

 tetrapods 1 



South Jetty 



Seaward of station 89+00 (Channel-side): 1 3,6 1 0-kg ( 1 5-ton) 

 tetrapods 1 



'Slope of tetrapods: 1V:1.5H. 



Placement of the armor units was consistent with observed wave exposure from the 

 southwest. Also, 90,720-kg (100-ton) concrete blocks were cast on the monoliths 

 and slid into the voids of the slope. However, despite repair and improvement work, 

 both jetties continued to experience extensive damage. Following the severe storm 

 seasons of 1958 and 1959, rehabilitation of both jetties took place from 1960 to 

 1963. Jetty trunks were repaired with 10,890-kg (12-ton) stones placed on a 

 1 V: 1 .5H slope in the eroded areas, while jetty heads were reconstructed using 

 18,140-kg (20-ton) concrete blocks as formwork for concrete pours. Two-hundred- 

 and-fifty 90,720-kg (100-ton) concrete blocks were placed around the seaward tip 

 of the south jetty. The head of the north jetty was armored further with armor 

 stones grouted with concrete. The el of the north jetty was raised to +7.6 m (+25 ft), 



Chapter 1 Introduction 



