DESCRIPTION OF PRESENT INVESTIGATION 



Ar ea of Investigation 



The study area at Virginia Beach is located on the Atlantic seaboard 

 22 miles north of the Virginia-North Carolina State line, about 7.2 miles 

 south of Cape Henry, and 19 miles east of Norfolk, Virginia (Figure 1). 



Methods of Study 



Sampling. Sand samples were collected at 25-foot intervals along 

 three transects (Figure 1), normal to the seashore, from the berm zone to 

 a depth of approximately 20 feet. Additional samples were collected at 

 shorter intervals in the breaker zone at the 15th Street and 3rd Street 

 transects (Table 5, Addenda). Sampling was accomplished by hand or with 

 pipe dredges. Technicians attempted to sample only the upper 2 centimeters 

 of the beach surface at all times. Offshore portions of the 15th and 3rd 

 Street transects were sampled from existing fishing piers. The offshore 

 portion of the transect at the Camp Pendleton boundary line was sampled 

 from a U. S. Army DUKW at pipe stations 25 feet apart. Additional samples 

 were collected at two places from the swash-backwash zone (Figures 1, 2), 

 from the vicinity of Rudee Inlet (Figure 3) in the zone where the inlet 

 outflow was expected to affect the sediment distribution, and from the 

 top of the swash zone (Figure 2) at 200-foot intervals parallel to the 

 shoreline. Samples along the transects were collected near the time of 

 low water. Samples from the top of the swash zone, Rudee Inlet, and the 

 swash-backwash zones were collected 2 to 3 hours earlier than those 

 collected from the transects. 



Samples from the berm, breaker, and shoaling wave zones of the three 

 transects were mixed and subsamples from this mixture used for determina- 

 tion of the average shape factor (Table 3) and mineral composition (Table 

 2) for the whole area. 



Determ ination of Shape Factor . A Corey shape factor was evaluated 

 (Table 3) for the fractions of the mixture of sands (mentioned above) 

 retained by No. 18 and No. 230 sieves (A.S.T.M. Sieve Scale). Triaxial 

 measurements were made microscopically with the aid of an ocular microm- 

 eter and the calibrated fine-focusing adjustment knob. Since the shape 

 factors calculated for both the coarsest and finest fractions were so close 

 in value it was considered unnecessary to make shape factor determinations 

 on any of the intermediate sized fractions. 



The Dynamic Shape Factor (DSF) was computed (Table 4) only for 

 samples from the 3rd Street pier transect, using Equation 8. 



Determination of Mean Settling Velocities and Nominal Diameters . 

 Forces acting on a sand grain that is settling in still water are the 

 gravitational forces (acting downward), and the fluid resistance and 

 buoyancy forces (acting upward). 



