Hydrodynamic and Sediment Transport Modeling for a New Container Terminal
Type:
Presented during:
WODCON XVIII - 2007 Orlando, Florida, USA
Authors:
Goodrich
Abstract: This paper presents a summary of the numerical model studies used to evaluate the potential environmental impacts to the Cooper River associated with the SC State Ports Authority's (SCSPA) proposed port expansion at Charleston, South Carolina. The studies were conducted in support of a comprehensive Environmental Impact Statement (EIS) required for permitting of the project. The project includes a new 3,510 ft wharf, berth and turning basin located at a former naval base. Several alternatives to the proposed project were evaluated for the EIS, including terminals across the river at Daniel Island and Clouter Island, as wells as different wharf alignments at the proposed site.
The Environmental Fluid Dynamics Code (EFDC) was used to simulate the changes to the river currents, salinity, and sedimentation patterns caused by the project. The hydrodynamics of the model were calibrated using in-stream continuous monitoring data of water surface elevation and salinity from nine USGS gages, as well as flow and velocity measurements collected by ATM at six transects near the project site. The model was used to simulate the project changes to current patterns in the river. Areas of particular interest included an adjacent marina managed by the county parks service and nearby piers used by the federal law enforcement training center.
The model was used to simulate changes to salinity near the project site and further upriver. Potential salinity intrusion impacts are an issue of concern because of an upriver freshwater intake at the Back River reservoir. Dam flows into the river are currently used as a management tool to avoid salinity intrusion to the Back River. The model was used to demonstrate that the project would not affect salinity intrusion to the Back River.
The sediment transport component of the model was calibrated using suspended sediment data collected by ATM in conjunction with historical sedimentation patterns in the navigation channel. The model was used to show the relative differences in maintenance dredging rates that would be required for each of the project alternatives. The study also estimated the total maintenance dredging rate for the proposed project.
The EFDC model currents were exported to the SSFATE model in order to simulate suspended sediment impacts from dredging operations. The model currents were also exported for input to a ship simulator set up by Marine Safety International for simulation, testing and evaluation by captains of the Charleston Branch Pilots.
The model results were also used to support conclusions regarding potential impacts to dissolved oxygen in the river near the project site, which is considered impaired (not meeting the water quality standard).
This paper presents a demonstration of the use of a single numerical model to support multiple aspects of a detailed environmental impact study of a port project, both by directly quantifying impacts to hydrodynamics and sediment transport as well as linking to other models such as SSFATE.
Keywords: EFDC, hydrodynamic, modeling, EIS, environmental impact study, Charleston, port, sediment.