It is well-known that the value of the nearbed sediment concentration peaks near the time of the passage of the wave crest, when the value of the wall stress reaches a maximum. But the presence of a second peak in sediment concentration near the time of flow reversal has also been observed in experiments. Using existing techniques for flow modelling of wave boundary layer and modelling of suspended sediment in combination with a new wall boundary condition for sediment the secondary peak has also been observed in numerical experiments. Evidence suggests that the second peak is caused by a break up in the boundary layer due to flow reversal leading to high diffusivitics near the wall.