calculated dump positions and plotted. In Figure la, any dump position is as likely as any 

 other. This pattern was obtained by generating a north coordinate and a corresponding east 

 coordinate uniformly distributed within the radius of operations. If the resulting distance 

 from the center of operations was greater than the radius of operations, the position was 

 rejected. The process was repeated until a satisfactory position was returned. This 

 distribution of disposal locations is used for capping operations to provide an even layer of 

 cap material over the entire radius of operations. The pattern in Figure lb was obtained by 

 generating a radial distance uniformly distributed from zero and the radius of operations. An 

 azimuth is generated uniformly between zero and 360 degrees. The resulting position is 

 guaranteed to be located within the radius of operations. However, the pattern is 

 considerably center-weighted which most likely simulates the positions of scows during 

 normal disposal operations. The watch circle of the disposal buoy would allow scows to 

 sometimes occupy the center of the disposal area. Because the scow operators are attempting 

 to occupy a position as close to the center as possible, the center- weighed distribution seems 

 appropriate. 



The model output is presented in the form of a two or four page report (depending on 

 whether the run is capping or disposal) and is generally based on the sum of many barge 

 loads of material distributed in space as described above. Figure 2 shows the distribution of 

 a typical single load of disposed material in shallow water (< 100 meters) for which this 

 model is designed. It can be seen that the distribution of material is flat near the center of 

 the mound. This is because in the shallower depths, there is not enough time for the 

 receiving water to penetrate into the center of the load of material and dilute the sediment 

 concentration. The overall guassian appearance, which is typical of a multiple-barge load 

 operation, is due to the smoothing effect of many mounds located at different positions and 

 overlapping. 



In addition to the user inputs provided during the model operation, several coefficients 

 and factors are provided in the text file DREDGE.D and can be changed if better values are 

 obtained. The entrainment, apparent mass, drag, and skin friction coefficients, as well as the 

 fall velocities, were obtained from Koh and Chang (1973). The in situ densities at the 

 disposal site (set at an average of 1400 kg/m 3 ) can be changed to reflect results from 

 previous dredged material disposal operations. The entrainment factors (H-FCT and C-FCT) 

 represent the amount of water added to the scow during dredging operations, with the hopper 

 dredge entraining more then the clamshell dredge. In order to allow the user to expand the 

 scale of the grid printouts for cases where the cap material may extend beyond the edge of a 

 grid defined by a small disposal run, P-FCT can be increased. Finally, if the attached 

 printer does not support graphics, the centerline plots can be eliminated from the output be 

 entering NO on the last line of the file. 



The most recent addition on the DAMOS Capping Model is the estimation of erosion 

 at a disposal mound. The EPA Equation Workbook Scientific Protocol for Ocean Disposal 

 Site Designation was used to develop algorithms for indicating the amount of loss of 

 sediment at a disposal mound over a fixed period of time. The overall sediment transport 

 rate was determined from the mean net bottom drift and the wave-induced bottom velocity. 

 Methods are presented to predict the frequency of storms capable of resuspending sediment at 



