Dredging operations consist of positioning the Punaise, connecting it to the umbilical/ 

 discharge line, lowering it to the seafloor, and commencing dredging. Prior to positioning the 

 Punaise, the shore station is established and the umbilical/discharge line is run from the shore 

 station out into the water. Once the Punaise is positioned, it is connected to the umbilical/ 

 discharge line and its ballast tanks are filled to initiate sinking. As the Punaise sinks to the 

 seafloor, the umbilical/discharge line also becomes submerged. Fluidizers in the suction pipe 

 allow the Punaise to continue settling into the sand as it reaches the bottom. When the suction 

 pipe becomes buried into the sand to the appropriate depth, dredging begins and a crater is 

 formed under the Punaise. As material is removed from the crater, the Punaise can continue to 

 settle until either the maximum depth of dredging is reached or the suction pipe encounters hard 

 bottom (clay, gravel, rock, etc.) (Figure 25). Depending on the site and desired operation, the 

 Punaise can either remain in place and continue to remove sand as the crater is filled, or it can be 

 floated to the surface and repositioned to a new location. 



Currently, there exist only two Punaises, which are operated in Europe by PinPoint Dredging 

 Company, Inc. (a subsidiary of J.G. Nelis Group), The Netherlands. Specifics of these two 

 systems are detailed in Table 19. Pumping distance, which is a function of grain size and 

 production, can be estimated from Figures 26 and 27. 



Table 19 



Punaise Systems (PinPoint Dredging Company) 



Characteristic 



PN250 



PN400 



Width 



7.8 m 



8.5 m 



Height 



Without suction pipe 



With suction pipe 



3.1 m 

 8.5 m 



6.0 m 

 8.7 m 



Draft 



7.5 m 



6.5 m 



Pump capacity 



800 m 3 /hr @ 6 bar 

 (1,046 yd 3 /hr@ 87 psi) 



2,400 rn 3 /hr @ 8 bar 

 (3,140 yd 3 /hr@ 116 psi) 



Working depth 



30 m 



4 to 40 m 



Discharge pipe diameter 



26.0 cm 



40.0 cm 



Weight/Mass 



47 metric tons 



95 metric tons 



Two scenarios exist for utilizing the Punaise at Shinnecock. The Punaise could be deployed 

 in the subaqueous, updrift fillet with the shore station located on the updrift side of the inlet. 

 Material dredged by the Punaise from the fillet (along 6.1-m contour) would be pumped to the 

 shore station location and then across the inlet to the desired point of discharge. This total 

 pumping distance is approximately 3,400 m (Figure 28). Assuming the Punaise PN400 can 



Chapter 5 Bypassing Alternatives 



65 



