Contaminated sediment sites often become focal points for extensive investigations and costly remediation efforts, frequently leading to complex, multiparty litigation. Numerical modeling plays a crucial role in these forensic studies, providing insights into sediment dynamics and contaminant transport.
The American Bar Association characterizes contaminated sediment sites as "a lightning rod for lengthy investigation and expensive remediation," noting that their size and complexity make them prone to litigation involving multiple parties. High-profile cases such as the Lower Duwamish Waterway in Washington, Portland Harbor in Oregon, the Lower Passaic River in New Jersey, and Newtown Creek in New York exemplify these challenges. In these instances, numerical modeling has been instrumental in supporting forensic analyses.
Client: Granite Shore Power, LLC
DSI provided a Senior Technical Consultant and Expert Witness to evaluate thermal discharges from the Merrimack Power Station on the Merrimack River, NH. The Sierra Club contended that the peaking operations from the power plant caused harm to the Hooksett Pool on the Merrimack River. We evaluated the plaintiff’s expert reports, large volume of thermal discharge data, and ambient condition monitoring to independently evaluate the plaintiff’s multiple statistical models. Several reports were generated and submitted to the court to support these findings.
Client: Weston Solutions, Inc., West Chester, PA
DSI provided the Senior Technical Consultant for the hydrodynamic modeling and sediment/PCB transport study portion of a major multi-year contaminated sediment remediation project directed by EPA for a 13-mile reach of the Housatonic River, MA, USA. The study uses the HSPF model to provide upstream and tributary flow boundary conditions, the 3D EFDC model for hydrodynamic sediment transport with coupled PCB three-phase partitioning transport and fate, and a bioaccumulation model for ecological risk. DSI performed detailed testing of the EFDC code and collaborated with the author to incorporate corrections and new bed mechanics, armoring, and toxic transport sub-models. We also developed a series of coupled 2-D and 3-D models of the river/pond reaches of the Housatonic River, including floodplains. The DSI team worked with the EPA/COE contractor to collect detailed supplemental data for a detailed 0.5-mile Test Reach, including bedload/suspended load and geomorphology. We also directed a COE Sedflume study and integrated the data into the modeling effort. Our team directed, analyzed, and interpreted a flow and velocity study using an Acoustic Doppler Current Profiler (ADCP).
Client: Sea Engineering, San Jose, CA
Mercury concentration in the sediments in the Port of Augusta has been found to be very high. The Italian Government has initiated a range of studies to investigate the extent of contamination and how to remediate the contamination found. DSI supported a study of the evaluation of water circulation around Augusta harbor and the levels of water exchanges between the water inside and outside of Augusta harbor. An EFDC model was built and calibrated using ADCP velocities.
Client: Ballard Sphar, LLP, Philadelphia, PA.
DSI developed a multidimensional hydrodynamic model of the Little Lake Butte des Morts (LLBdM) on the Lower Fox River. The objective was to support the development of a conceptual model of sediment and PCB transport dynamics in the LLBdM (Operable Unit 1) and releases downstream. The insights gained in the modeling provided an enhanced conceptual understanding of sediment dynamics in LLBdM. This, in turn, impacted the interpretation of historical and ongoing studies. Our team conducted a field program using an Acoustic Data Current Profiler (ADCP) to collect flow and bathymetry data for the LLBdM. We then processed and integrated the data into the modeling framework. The Environmental Flow Dynamics Code (EFDC) was set up and calibrated. This model was then used to determine flow patterns, and bed shear stresses were evaluated for a range of flow and wind conditions.
Client: Gault, Marshall & Miller, PLLC, Paducah, KY
DSI provided the Senior Consultant and Expert Witness for a hydrodynamic study of the Belleville Locks & Dam for the M/V Jon J. Strong Accident on January 6, 2005. During a high-flow event, a tow pushing a group of barges broke loose and were swept downstream into the dam’s spillway. Our team built two hydrodynamic models for the upstream and the downstream regions of the dam. We calibrated the models to physical model studies conducted during the design phases of the new hydropower units installed. We used the calibrated models to predict the velocity fields influencing the tows. These flow patterns were then used by barge navigation experts to determine the possible cause of the accident.
EFDC+ has proven to be an invaluable tool in managing contaminated sediment sites, offering comprehensive modeling capabilities that support litigation and remediation efforts. Its application in various high-profile cases underscores its effectiveness in addressing the multifaceted challenges associated with contaminated sediment management.