Using a combination of mathematical analysis and numerical calculations, a study will be conducted of particle transport in surface wave induced oscillatory boundary layers over a sediment bed. An existing theory of homogenization will be extended and applied to this problem. The theory deals with physical phenomena involving several widely different scales. In this case, two very different scales are the flow forcing length and the suspended particle layer thickness. Dispersion coefficients and dispersion patterns will be determined, with forcing from both waves and tidal action. The research will have impact on the more reliable prediction of coastal sediment transport, relevant to beach protection and bay and harbor silting.