Strategic placement for beneficial use of dredged material

Abstract

The U.S. Army Corps of Engineers and the U.S. Environmental Protection Agency are changing their perception of dredged material, from a byproduct of the dredging process to a valuable resource. The negative perception of navigation dredged material is codified under the 1972 Clean Water Act Section 502, which specifically defines "dredge spoils" as a pollutant, along with solid waste, sewage, and garbage. However, navigation dredged material is typically a mixture of sand, silt, clay, and possibly gravel. These sediments resources are critical to controlling flood risks and providing environmental benefits. This document provides details regarding the use of dredged material to support NNBF through strategic placement. Strategic placement is the process of placing sediment at one location with the expectation that hydrodynamic and possibly aerodynamic forces will transport specified classes of that sediment to desired locations. Strategic placement is a beneficial use option that may have less negative impact on the final receptor sites and often can be performed at a reduced cost when compared to direct placement (such as beach nourishment). Cost controls are critical to developing sustainable dredged sediment management plans that address the Federal Standard, which guides the disposal and placement of dredged material.

Evaluation Techniques for the Beneficial Use of Dredged Sediment Placed in the Nearshore

“…Chetco Inlet, Oregon (1996-2013 From 1996 to 2013, 277,000 m 3 of dredged sediment was placed south of Chetco Inlet, Oregon, in depths from 4.9 to 7.9 m. The placed sediment was actively transported in the littoral system and the sediment was placed in the same location annually (Gailani et al 2019). The dredged material was described as silty gravel.…”

Evaluating Transport Formulations for Application to Nearshore Berms

“…Longshore transport has been observed to dominate nearshore berm deflation in both laboratory experiments (Smith et al 2015;Bryant and McFall 2016;Smith et al 2017) and field observations (e.g., Vilano Beach, FL, Brutsché et al 2019; Chetco Inlet, OR, Gailani et al 2019;Perdido Key, FL, Brutsché et al 2015;andTerschelling, the Netherlands, Hoekstra et al 1997, Spanhoff et al 1997). Cross-shore transport may also remove placed sediment from its original location, particularly during storm events (Bodge 1994;Otay 1995;Brutsché et al 2014).…”

Detailed modelling to evaluate the effectiveness of sediment recycling on coastal habitat

“…Often, the beneficial use of sediment for habitat improvement is found to be unviable due to the increased costs of placement, achieving consent and monitoring, and the problems involved in demonstrating benefit (Murray, 2008;Brils et al, 2014;Ulibarri et al, 2020). However, there is an increasing recognition that dredged sediment is a resource which should be utilised beneficially for human development activities and/or enhancement of ecological habitats (CEDA, 2019;Gailani et al, 2019). The need to seek beneficial use opportunities has been identified as a priority within the International Maritime Organisation London Convention and London Protocol (IMO, 2014) and other dredged material management reviews and guidance (e.g., IADC, 2009;CEDA, 2010;OSPAR, 2014;;HELCOM, 2015) and more recently in the COP26 Climate Change and Sediment Management Pledge (SEDNET, 2021).…”

“…The beneficial use of dredged sediment has grown dramatically over the last 30 years for a range of uses: to maintain the integrity of local wetland habitats, as a source of material for flood defence, as a source of reclamation fill, to aid the clean-up of contaminated or old mining sites and as building material (e.g., CEDA, 2019). In the US, for instance, the United States Army Corps of Engineers (USACE) have been world leaders in the use of dredged material for habitat creation, using around 33% of the 200 million cubic yards of coastal navigation channels dredged by the USACE every year are used beneficially (Gailani, 2019), proving successfully that dredged sediment can be used to restore create valuable that provide critical habitat for wildlife (Ausden et al, 2018). This increased emphasis on beneficial use arises partly due to recognition of the symbiosis of coastal development and the environment as encapsulated by concepts such as Engineering with Nature © (https://ewn.erdc.dren.mil) or Building with Nature (https://building-with-nature.eu).…”