Field study of the effects of storms on the stability and fate of dredged material in subaqueous disposal areas.

Long Island Sound is a large estuary. Dredged sediment placed on the bottom of the Sound is subject to dispersion by the tidal stream, estuarine circulation, waves, and disturbances of the hydraulic flow field by storms. Repeated bathymetric surveys of a deposit of dredged material at the New Haven disposal site show that after initial self-consolidation of the mound, no significant changes in pile configuration occurred over a three-year period; erosion of the deposit is not detected. The data obtained show that to best contain silt clay dredged material, the disposal site should be on a naturally accreting mud bottom, the disposal operation should emplace a large volume of material on the site expeditiously, and the deposit should be built to an optimum configuration. The capacity of the disposal site is limited by the maximum height of the disposal mound and the maximum slope of the pile sides which present a minimum disturbance of the natural hydraulic regime. The capacity of the New Haven site is estimated to be up to 1.7 x 10SUB6 ydSUB3 of unarmoured, silty, dredged material. Larger volumes may be contained if the surface of the deposit is armoured with coarser material. (A)