New Standard Weir Design for Dredged Material Management Area, Jacksonville District

摘要

Dredging supports ports and harbors and the nation s transportation infrastructure by maintaining or creating navigation channels, similar to the way that highway construction maintains or creates highways. One of the primary aspects of any dredging project is deciding where to place the dredged material. In basic terms there are only two choices; place the material in the water or place it on land. When dredged material is placed on land, the process is usually called upland placement of dredged material. When placed upland, dredged material is usually accompanied by large amounts of water and a containment area is usually required to temporarily hold the water and permanently hold the dredged material. The containment area is known as a dredged material management area (DMMA), dredged material disposal facility (DMDF), confined disposal facility (CDF), or by similar nomenclature. In order to separate water from dredged material, a DMMA usually includes an outlet structure for letting supernatant water return to the natural water body from which it was entrained by the dredge. The outlet structure is usually a weir box. In general, DMMA weirs are designed with three major purposes in mind: 1) to retain all of the dredged sediment solids within the DMMA, 2) to let the excess water leave the DMMA and return to the natural water body, and 3) to prevent scour or resuspension of settled solids and control the release of water in such a way that suspended solids (usually measured with respect to turbidity) within the return water are kept to a minimum.