Figure 23. Rodman in the surf (16 January 1968). 



a single crew or split into two three-man crews to expedite the work. The 

 crew also collected sand samples at various times at selected profile lines. 



In addition to surveys by conventional surveying methods, an experimental 

 program was conducted to test a method of obtaining profiles by observing sand 

 levels on pipes located at approximately 15-meter intervals along selected 

 profile lines (Urban and Galvin, 1969). Profile lines 5 and 7 at Atlantic 

 City were selected for this program. 



To establish the pipe profiles, 6.4-meter-long iron pipes (marked at 0.15- 

 meter intervals and usually marked before emplacement) with 3.8-centimeter 

 (inside) diameters were jetted 4 meters into the sand. A type of reflecting 

 material or a sign was displayed on the pipes as a safety measure for beach 

 buggy traffic at night. 



Unpaid local observers enlisted by the Philadelphia District made weekly 

 observations of the sand elevation at each pipe. These observations were 

 recorded on forms and mailed weekly to CERC. At CERC, the sand elevations 

 were converted to elevations above MSL and the data were stored in the stan- 

 dard survey format. These data are available in Urban and Galvin (1969). 



4. Accuracy of Field Surveys . 



A certain degree of error is inherent in any data collection procedure, 

 even under the most ideal conditions. Some of the possible errors encountered 

 throughout these surveys are discussed below. 



Random reading errors were minimized by using a rod graduated in tenths of 

 a foot. Since the only readings requiring a greater precision (to the nearest 

 hundredth of a foot) were at the bench mark and at turning points, and these 

 sight lengths were usually less than 76 meters (250 feet), no significant ran- 

 dom error should occur (Czerniak, 1972). 



29 



