Formatted Title:

Increasing Sustainable Beneficial Use Opportunities Working with Contaminated Sediment

Background/Objectives:

Traditional remediation of contaminated sediments includes dredging and disposal in landfills or confined disposal facilities (CDFs), which can be costly and result in the loss of valuable aquatic habitat. Integrating contaminated sediments into beneficial use targets is a sustainable approach to resource management that requires forethought and innovation to identify environmentally protective approaches. Beneficial use evaluations of contaminated sediments are more complex than clean sediment evaluations, partly because reuse of contaminated sediment also must protect human health and the environment. For this reason, contaminated sediment is often excluded from beneficial use considerations.

The U.S. Army Corps of Engineers (USACE) Engineering Research and Development Center (ERDC) is seeking innovative methods to use contaminated sediment beneficially and to include contaminated sediments in their 70/30 goal (70% beneficial use by 2030). By using contaminated sediment beneficially, valuable resources can be conserved, reducing the need to extract clean materials and the cost and burden of contaminated sediment landfill disposal. However, it is essential to ensure that the beneficial use of contaminated sediment does not cause further harm to the environment or human health or interfere with infrastructure function and navigation. While CDFs were originally built decades ago to confine contaminated sediments, much of the sediments more recently placed in CDFs are relatively clean, having been placed there due to cost or other efficiencies in dredged material management.

Approach/Activities:

Beneficial use of contaminated sediment can be realized by resourcing cleaner sediment from existing (and sometimes near-full) confined disposal facilities, thereby opening up air space for contaminated sediment that eventually will be used to form new lands. This study recognizes the complexities of creating a market for dredged clean sediment in CDFs and those associated with retooling existing CDFs to manage contaminated sediment. Existing CDFs that receive relatively clean dredged material (some close to capacity) can provide a valuable resource for construction materials, soil amendments, upland fill, and habitat restoration. By salvaging clean sediment from existing CDFs, those same CDFs can be repurposed for other materials, whether for contaminated sediment disposal or ongoing placement of clean sediment dredged primarily from navigation dredging. CDFs with contaminated sediment can be capped and, when filled, used beneficially as newly created uplands. This approach creates dual opportunities for beneficial sediment use. The first opportunity is to use clean material salvaged from existing CDFs, and the second opportunity is to use contaminated material as a foundation for new lands, whether used for commercial/industrial development or as a park for recreation.

Results/Lessons Learned:

A life cycle analysis (LCA) and cost benefit analysis (CBA) are essential in evaluating the economic feasibility of integrating contaminated sediments into beneficial use. Both are integral to understanding the long-term potential for success for CDF sediment reuse. LCA/CBA consider the costs associated with sediment treatment, extraction, transportation, and repurposing, as well as potential benefits, such as reduced disposal costs, reduced need for quarried clean material, improved environments, and new economic opportunities. By quantifying the costs and benefits, decision-makers can assess the financial viability of the beneficial use process and make informed choices. Working with the USACE Detroit District, this paper presents the results of an LCA/CBA model that considers the entire life cycle of the sediments, from dredging or extraction to final disposition or end uses, including energy consumption, greenhouse gas emissions, socio-economic benefits, and other indicators. This paper identifies factors, criteria, and life cycle analysis tools to be considered in decision-making processes to optimize the environmental and economic benefits of repurposing clean and contaminated sediments while minimizing potential risks.

Clare Leary

Affiliation

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(Group 1, Poster Board #68) Increasing Sustainable Beneficial Use Opportunities Working with Contaminated Sediment