2.0 DAMOS CAPPING MODEL VERIFICATION 



The DAMOS Capping Model was designed to predict the configuration of a dredged 

 material disposal mound and help estimate the amount of material needed to cap the mound 

 adequately. Previous analysis of the model determined that it provided an accurate basis for 

 cap volume estimations and generally predicted the lateral extent of disposal mounds but did 

 not predict mound height accurately. 



The ability of the DAMOS Capping Model to predict lateral extent and height of 

 dredged material was tested using data from five disposal mounds in Long Island Sound as 

 variables: CLIS-89 and CS-90-1 at CLIS, the WLIS "D" mound at WLIS, and mounds NL- 

 88 and NL-TR at NLDS. Systematic changes in the parameters, or data sets, from each 

 mound were used to determine if the parameters could be refined to improve the model's 

 accuracy in predicting mound height. The effect of changes in the parameters on predicted 

 mound height could not be isolated from the effect of the random distribution pattern built 

 into the model. The DAMOS Capping Model was then run numerous times with an identical 

 data set to determine the number of model runs necessary to obtain an average mound height 

 to specified confidence limits. 



Attempts to verify the accuracy of the DAMOS Capping Model by using data from 

 the Long Island Sound dredged material mounds showed that the model's predictive accuracy 

 is dependent on the degree of accuracy in the composition, amount, and placement of 

 dredged material during a disposal operation. If these parameters are correct, five runs of 

 the model with the same set of parameters will predict a mound height to the 90% confidence 

 level. It is important that the distribution of dredged material at the site be controlled to 

 mimic the center- weighted distribution that is predicted in the model. With this control, the 

 dredged material will form one peak as predicted by the model. 



The behavior of the dredged material over time is not factored into the model. 

 Consolidation can result in significant changes in mound height depending on the type and 

 amount of dredged material, whether the mound was capped, and the composition of the 

 capping material. If the DAMOS Capping Model is used to predict the height of a dredged 

 material mound at any time after deposition, the effect of consolidation must be considered. 



For further information see: Wiley, M. B. 1994. DAMOS capping model verification. 

 DAMOS Contribution No. 89 (SAIC Report No. SAIC-91/7603&C95). US Army Corps of 

 Engineers, New England Division, Waltham, MA. 



DAMOS Summary Report, 1985-1990 



