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Title: State-of-the-art applicability of conventional densification techniques to increase disposal area storage capacity
Authors: Johnson, Stanley J.
Cunny, Robert W.
Perry, Edward B. (Edward Belk)
Devay, Leslie
Keywords: Soil stabilization
Dredging spoil
Dredged material
Publisher: U.S. Army Engineer Waterways Experiment Station
Series/Report no.: Technical Report (Dredged Material Research Program (U.S.)) ; no. D-77-4
Abstract: Dredging to maintain or increase project depths in navigable channels and harbors often requires confined dredged material disposal areas. In many localities it is difficult to find suitable confined disposal areas, and even where available, environmental constraints may prevent or restrict their use. Restrictions may be placed on allowable heights of retaining dikes and depths of dredged material placed in disposal areas. The purpose of this study was to determine if conventional stabilization techniques can he used to densify/dewater dredged material as a means for increasing the storage capacity of disposal areas. This was done on a judgment basis and without laboratory or field research. Coarse-grained dredged material was not included in this study, which was restricted to clays and silty clays, which have high water contents after placement in disposal areas. It was concluded that conventional stabilization techniques can be used to increase disposal area capacity but that economic constraints may restrict their use in some areas. It was found that the water content, density, and Atterberg limits of fine-grained dredged material in existing disposal areas are inadequately known, and a large-scale but relatively low-cost sampling program is recommended to investigate existing disposal areas of various ages containing various depths and types of dredged material. A variety of conventional stabilization techniques were evaluated. It was concluded that seepage consolidation and underdrainage with vacuum pumping offer significant potential and should be investigated. Desiccation of dredged material placed in thin layers is especially attractive both in regard to cost and quantity of additional storage capacity achieved, even though the concept may have limited application. Selected research is recommended and is considered essential. This includes construction of simple but large-scale sedimentation consolidation test devices to investigate fundamental aspects of stabilization processes and benefits of various stabilization techniques. The increase in storage capacity available from densification treatments should be compared with the alternative of raising the height of retaining dikes and placing greater thicknesses of dredged material in disposal areas. The latter is generally more economical, but may not be possible in some localities because of environmental constraints or because weak foundations are a limiting factor for small disposal areas. Where disposal area foundation consolidation and/or thickness of dredged material is large, densification treatment is especially beneficial. Appendixes include a description of river sediments, a general description of conventional densification techniques, and calculations for the economic evaluation of densification techniques. (The appendixes were pre-pared on microfiche and are enclosed in an envelope in the back cover.)
Description: Technical Report
Gov't Doc #: Technical Report D-77-4
Rights: Approved for Public Release; Distribution is Unlimited
Size: 221 pages / 17.9 MB
Types of Materials: PDF/A
Appears in Collections:Technical Report

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