Based on a puff model

and together with the consideration of convection

dispersion and descent of suspended waste particles in marine environment

a numerical model is presented to predict the initial sedimentation of waste particles discharged from ocean outfalls in coastal waters and to compute the stable sedimentation rate in homogeneous trde current fields with water depth constant. When the time step selected is small enough

the results from this model agree well with that from the semi-analytical solution

and have sufficient precision for evaluating the impact on the environment caused by sedimentation of waste particles discharged from ocean outfalls. A numerical example is given for predicting the sedimentation of waste particles discharged in Heishijiao

Dalian.