Capacity Enhancement at Coastal Disposal Sites

The coastal environment is host to a large number and variety of disposal facilities, including dredge disposal sites and landfill sites. Because these sites are commonly located over weak foundation soils, it is difficult to maximize the disposal capacity without risking foundation instability or general instability and, as a result, the disposal capacity of these sites is often not maximized. Recent advances in foundation improvement and design, though, have made it possible to significantly, and reliably, extend the service life of coastal disposal sites. The purpose of this paper is to describe the challenges faced by disposal facilities that are designed in coastal environments and to present a case history of a recent construction project at the confluence of two rivers in which substantial additional service life was provided using innovative design techniques and comprehensive construction oversight which resulted in construction cost savings well over ninety percent when compared to the original conventional design. The successful design and construction over extremely soft dredge using innovative design and construction techniques described in this paper opens opportunities not only for extending the life of disposal facilities next to riverfront environments but also for raising levees and dikes cost effectively at critical locations that are prone to flooding.