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Computer simulation models have been used to support decision-making at contaminated sediment sites for decades. Nonetheless, their reliability in remedial decision-making has been questioned, and there is a need for retrospective studies of the accuracy of model predictions, that is, post-audits. The Neal's Landfill site near Bloomington, Indiana, provides an example of the successful use of a mathematical simulation model in the selection of a remedy for a site that includes streams with polychlorinated biphenyl (PCB)-affected sediment, water, and fish. A chemical fate and transport and bioaccumulation computer simulation model was developed to compare the effectiveness of alternative remediation plans in reducing fish total PCB concentrations. A post-audit of the model, using several years of data collected after remediation, demonstrates that the model successfully predicted declines in surface water and fish tissue PCB concentrations over a decade, including those associated with longer term natural recovery processes as well as the response to remedial actions. The model predicted, and the post-audit bore out, that risk-based goals would be met using an alternative less extensive than others under consideration. An uncertainty analysis, based on bounding model calculations, provided important support for decision-making, as did the inclusion of a statistical Remedy Confirmation Clause in the Consent Decree for the site. This study demonstrates the utility of a computer simulation model to guide remedial decision-making at a contaminated sediment site. Integr Environ Assess Manag 2022;18:1233-1245. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental ToxicologyChemistry (SETAC).

Glaser, D., J.R. Rhea, D.R. Opdyke, K.T. Russell, C.K. Ziegler, W. Ku, L. Zheng and J.J. Mastriano. 2009. Model of zebra mussel growth and water quality impacts in the Seneca River, New York. Lake Reserv. Manage. 25:49–72. A dynamic water quality model was developed to support management decision-making for the Seneca River, New York. The model incorporated two-dimensional hydrodynamics to simulate stratification observed within the system, a carbon-based zebra mussel growth model to account for the impact of this invasive species on water quality within the system, and a mechanistic representation of sediment diagenesis to account for zebra mussel-induced changes in carbon cycling. The Seneca River is on New York State's 303(d) list of impaired water bodies for nonattainment of dissolved oxygen criteria and is being considered as the potential receiving water for diverted effluent from an 85 million gallon per day (MGD) wastewater treatment plant (WWTP) serving the City of Syracuse, New York. Th...

A mechanistic model of PCB fate, transport, and bioac cumulation in the Upper Hudson River was developed to provide a quantitative tool to assess the effectiveness of natural recovery and active remediation in reducing PCB levels in water, sediment, and biota. The fate and transport modeling, which is the subject of this paper, builds on previous approaches by using a mechanistic sediment-transport model that describes erosion and deposition with sufficient accuracy to remove the requirement to adjust sediment transport as part of the contaminant calibration process. An additional significant aspect of the model is the calibration and validation for both the short time scale of erosion events and the decade-long time scale associated with trends in sediment contamination.The model demonstrates differences between PCB fate in cohesive and noncohesive sediments that are important to efforts to reduce perceived human health and ecological risks. Burial due to the deposition of solids with lower PCB concentra...

The water quality of Onondaga Lake, NY has been compromised by a 100-year history of municipal and industrial pollution. A state-of-the-science water quality model was developed for the system to facilitate contemporary water quality management which includes: 1) development of total phosphorus and ammonia TMDLs and 2) assessing the feasibility of diverting a large point source discharge out of the Lake and into an adjacent river system. The OLWQM consists of a number of submodels representing the major hydrodynamic, water column nutrient cycling, and sediment processes controlling water quality in the lake. The water column submodel describes nitrification, organic matter decomposition, algal photosynthesis, respiration, and nutrient uptake, and zooplankton and zebra mussel grazing and respiration. The sediment flux submodel simulates the conversion of particulate organic material settling from the water column to dissolved nutrients and the concurrent consumption of oxidized compounds from the overlying water column. The model was calibrated over the period from 1994 to 2003 and successfully simulated the major water quality dynamics observed within the system. Additionally, the model simulated the gross patterns in chlorophyll-a in the epilimnion as well as phosphorus retention within the lake sediments. Finally, the model was able to simulate compliance-based measures of important water quality standards and guidance values developed for the lake. The next step of model development includes linkage of the Lake model with a model of the adjacent river system and validation of the linked models.