Desiccation and Consolidation of Dredged Materials

A mathematical model, which numerically solves the boundary value problem representing these physical phenomena, is applied in conjunction with the results of an extensive experimental investigation to (1)Calculate the settlements that are predicted for the dredged materials placed in the Penn 7 disposal area in Toledo, Ohio; and (2)evaluate the effect that modifications in the boundary conditions have on the consolidation behavior of the fill. Although drainage conditions at the bottom of the layer do exert some influence on the consolidation rate during deposition of the dredgings, the evapotranspiration potential renders this effect almost negligible when desiccation takes place at the surface. On the other hand, transpiration plays an important role on the consolidation rate during the early stages of desiccation, but this effect is reduced considerably as the water table approaches an equilibrium position. In summary, theoretical results indicate that significant improvement in the consolidation behavior of dredged materials can apparently not be achieved with low cost modifications in the boundary conditions, but the use of vegetation with high transpiration rates appears to offer considerable promise.