The tidal wetland restoration goldmine: Prospects and pitfalls of mining confined disposal facilities.

Saltmarshes along the United States South Atlantic Coast, and globally, face critical threats from sea-level rise, edge erosion, ponding and historical human modifications, all of which are exacerbated by sediment deficits. Uncontaminated sediment stored in confined disposal facilities (CDFs) represents a significant and often overlooked resource for marsh restoration. As a result of management practices in the second half of the twentieth century, many unnaturally high earthen structures occur adjacent to drowning saltmarshes in the United States. In this perspective article, we explore the potential for mining CDFs to provide the sediment necessary to restore and sustain at-risk saltmarshes. Using publicly available data from the US South Atlantic coast, we estimate that reclaiming sediment from existing CDFs could offset sea-level rise impacts by 2100 for 13% of South Atlantic marshes. While the potential benefit is substantial, scientific, planning and implementation hurdles are presented. These pitfalls include potential issues with sediment characterization, limited guidance on chemical evaluation to reduce environmental risks, construction complications due to soft soils and legal and financial considerations. Despite these barriers, we conclude with a path forward for researchers and practitioners to address the hurdles through dedicated case studies, adaptive management principles and stakeholder engagement.