

3.25 



250# SCREEN 



WASHER 



ROTATE TO OPEN 



PVC CAP 



Figure A14. James and Brenninkmeyer suspended sample bag trap 

 (from James and Brenninkmeyer 1971) 



analysis of the sediment. These types of samplers have 

 several disadvantages which include: (a) the movement of 

 the bamboo pole varies the elevation at which samples are 

 collected, and erratically affect the hydraulic and 

 sediment -trapping efficiencies; (b) the concrete base will 

 induce scour; and (c) the effects of orifice opening and 

 collection area on the hydraulic and sediment- trapping 

 efficiencies are unknown. 



(3) Pumping/ siphon samplers 



Nearshore pumping samplers are very similar to riverine 

 pumping samplers, consisting of a nozzle and hose through 

 which a water -sediment mixture is pumped. Watts (1953) 

 developed and tested in the laboratory and field a sampler 

 that pumps a sediment -laden mixture at a point, sieves the 

 sediment, and discharges the water back into the ocean 

 (Figure A15). Efficiency curves for the sampler with a 

 vertically-oriented 1/2 in. (1.3 cm) nozzle were developed 

 based on maximum orbital velocity of the waves; the sampler 

 had an average efficiency of 94 percent if the orbital 

 velocity of the wave varied from to 5 ft/sec (1.5 m/sec). 



A24 



