Approaches to Coastal Wetland Restoration: Northern Gulf of Mexico

Authors: Turner, R.E. and Streever, B.

Year: 2002

Reference: Turner, R.E. 2002. Approaches to Coastal Wedland Restoration: Northern Gulf of Mexico. Kugler Publications. Accessed on 1-15-15

Summary: Thin layer placement has been performed since the 1930s due to engineering constraints. High pressure spray of dredged material was first conducted in Louisiana in the early 70s. It was generally found that less than 15 cm of placed material allowed for rapid recovery. Thicknesses ranging from 18-38 cm showed delayed recovery. The ability to convert shallow open water to vegetated marsh is possible. Important planning considerations are listed. The placed material can sometimes sink into the native soft sediment and can also be transported off site. Long-term monitoring (10 years) did not show significant differences between dredged material placement sites and reference sites. Cost comparisons relating high-pressure spray placement to bucket dredging are provided. Monitoring of thin-layer placement may involve different attributes of plant health and several different soil/sediment parameters. Planning considerations for thin-layer placement include: site access, the ability to operate the spray equipment intermittently and in a controlled manner, limitations spraying to areas 30 to 80 meters wide, a range of soil types can be sprayed and effects the liquefied slurry behavior, and wind and wave action.

What You Will Find Here: Dredged Material Wetlands p. 77, Thin-Layer Placement p. 115