Dewatering of reservoir sediment slurry using woven geotextiles. Part II: Analytical results

ABSTRACT: Geotextiles are increasingly being utilised in dewatering dredged reservoir sediment, as part of the sustainable management of reservoirs. To this end, analytical models for evaluating the effluent rate through geotextile dewatering systems have been developed. The proposed analytical model consists of Stokes' and Gibbs' particle-settling-velocity equations in evaluating the time-dependent soil cake formation upstream of the geotextile filter. Analytical results show good agreement of the predicted effluent rates with those observed in a series of laboratory falling-head dewatering column tests using two reservoir sediment slurries and four woven geotextile filters. Analytical results also show that the hydraulic conductivity of the soil cakes plays a key role, their compressibility plays a secondary role, and the permeability of the geotextile filters plays a minor role in accurately evaluating the effluent of a geotextile dewatering system. Stokes' particle-settling-velocity equation provides a better evaluation for the effluent rate, compared with that using Gibbs' equation. For Bai-Her sediment, which consists of relatively coarse particles, the advantage of the analytical model using Stokes' equation becomes more evident as the initial water height increases.