

.% tfT^O/fi 







SCALE IN FEET -y^iC.^ Jr- ^'. 









1000 2000 3000 ' ' ~J {'." § ■' 







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>^=- JETTIES 





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MANASQUAN 





INLET 





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MANASQUAN 

 RIVER , 



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Figure 48. Layout of Manasquan Inlet jetties, New York 



The Manasquan Inlet project was monitored during the period June 

 1982 to October 1984 under the MCNP program (Gebert and Hemsley 

 1991). Objectives of the study were to evaluate the performance of the 

 dolos armor units in maintaining structural stability of the jetties, deter- 

 mine potential effects of the rehabilitated jetties on longshore sediment 

 movement at the inlet, and determine the effectiveness of the rehabilitated 

 jetties in maintaining a stable inlet cross section. Data collection included 

 wave measurements, tidal elevation and current measurements, side-scan 

 sonar surveys, hydrographic surveys, limited ground surveys, aerial pho- 

 tography, and photogrammetric analysis. The jetties were subsequently 

 monitored under the "Periodic Inspections" work unit of the MCNP pro- 

 gram from August through November 1994 (Bottin and Gebert 1995). 

 Monitoring consisted of limited ground surveys, aerial photography, pho- 

 togrammetric analysis, and a broken armor unit survey. Detailed 

 photomaps of the above-water portion of the structures were obtained. 

 The monitoring revealed void areas on both jetty heads. On the north 

 jetty, the void area was on the south side of the head. The void area on 

 the south jetty was at its tip, and core stone was exposed in this location. 

 Emergency repair work, consisting of the placement of grout-filled bags, 

 was completed subsequent to the survey on the south jetty as a temporary 

 measure. 



The Manasquan Inlet jetties were inspected on 10 June 1997. The 

 14,515-kg (16-ton) dolos armor units are shown in Figure 49. Visual com- 

 parisons of armor unit positions on the north jetty to 1994 photomaps 

 revealed that several units had moved slightly. Horizontal movement ap- 

 peared to range from 0.15 to 0.6 m (0.5 to 2 ft). In addition, it appeared 

 that the downslope portions of most of these units had slightly lost 



Chapter 2 Project Descriptions and Inspection Results 



43 



