Contaminated Sediment Management
Challenges with Litigation Support
The American Bar Association describes contaminated sediment sites as “a lightning rod for lengthy investigation and expensive remediation. Based on the size and scope of these sites, they are ripe for litigation with multiparty involvement.” They go on to describe litigation related to the Lower Duwamish (WA), Portland Harbor (OR), Lower Passaic (NJ), New Town Creek (NY). Numerical modeling is a key component of supporting such forensic studies and EFDC is being used in all these cases.
Solutions Provided by EEMS
EEMS is a robust tool that provides powerful sediment resuspension and transport capabilities, coupled with several toxics sub-models. The extensive bug fixes and fast run time available in EFDC+ make it the first choice for EFDC models. Both of the EFDC+ sediment models are fully coupled to the toxics sub-models. The conventional EFDC sub-model developed at Virginia Institute of Marine Science accurately simulates cohesive and non-cohesive transport and has been used with toxics for many years. Alternatively, the user may now select to use the start-of-the-art SEDZLJ sub-model developed by Sandia National Labs. This is an increasingly favored approach and an improvement on previous models because it directly incorporates site-specific data (flume studies), while maintaining a physically consistent, unified treatment of bedload and suspended load. In EFDC+ important bug-fixes are available, including maintaining mass balance, and linkage to the toxics sub-model making it the go-to model for future studies.
Examples of Studies Done with EEMS
Between 1954 and 1971, paper producers along the Fox River in northeastern Wisconsin used polychlorinated biphenyls (or PCBs) to make a particular kind of carbonless copy paper, and other paper mills along the River made different products with recycled waste paper that contained PCBs. The Environmental Enforcement Section (EES) has taken a lead role in requiring the cleanup of PCB-contaminated sediments at the Fox River Site and in pursuing recovery of damages for injuries to natural resources in the area. A multidimensional hydrodynamic model of the Little Lake Butte des Morts (LLBdM) was developed in order to support studies of sediment transport dynamics in the Lower Fox River. This 3D model enhances the existing conceptual understanding of flow dynamics and observed particle deposition patterns in the vicinity of Little Lake Butte de Morts. Specifically, the model was used to explore spatial variability in hydraulic residence time, flow velocity, and bed shear stresses, and to provide insight into the relationship between solids transport, deposition, and erosion, and the observed pattern of PCB deposits within this reach of the Lower Fox River. The insights gained in the modeling provided an enhanced conceptual understanding of sediment and PCB dynamics in LLBdM. This in turn impacted the interpretation of historical and ongoing studies.
Newtown Creek Hydrodynamic and Sediment Transport Studies
“Newtown Creek was designated a Superfund National Priority Site in 2010/2011 under the guidance of the USEPA. A complete condition survey, last performed in 1991, was performed in April 2009 by the USACE New York District. Sampling and testing for possible future upland placement will be coordinated with the NYSDEC, NYCDEP and other stakeholders. The entire channel was last dredged in 1951 with the removal of 80,000 cys of material. In the 1950s and 1960s, portions of Dutch Kills and English Kills were dredged. The channel has been subject to various industrial contaminant inputs along the river over the past several decades. As a result, the material to be removed may be too contaminated to dredge and place in approved upland sites. New York City Department of Environmental Protection is the local sponsor. Economic re-development of the area is planned. Coordination with the NYCDEP is maintained.” Source
EFDC is being used extensively in hydrodynamic and sediment transport models that will be applied to Newtown Creek, New York. It is selected due to being open source and being linked to a sediment transport model that has the capability to utilize erosion rate data obtained from Sedflume testing (i.e., SEDZLJ capabilities). Section 4, Modeling Memo 1
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