Sediment Management Alternatives for the Biloxi Ports

Pevey, K., & McAnally, W. H. (2010). Sediment Management Alternatives for the Biloxi Ports. Mississippi State University: Civil and Environmental Engineering Department.

The objective of this project is to determine the source of sedimentation in the Ports of Biloxi and provide engineered solutions which will reduce or eliminate the need for dredging within the ports. The Commercial Docking Facility, Small Craft Harbor, and Point Cadet Harbor are all are located on the Biloxi Channel, an East-West channel that runs between the mainland and Deer Island. The Biloxi Channel provides a 12’ x 150’ dredged channel connection from the Intracoastal Waterway on both the east and west side of Deer Island. It is maintained at 10’ x 150’ between the facilities north of Deer Island. The Lighthouse Commercial Docking Facility is located on the Back Bay of Biloxi. Field sampling included water samples and sediment samples taken in and around the ports and in the Biloxi Channel. Samples were collected between January and June 2009, with the exception of storm event samples taken in November 2009. Velocity measurements were taken in the Biloxi Channel and across each harbor entrance. These velocities, along with tidal data, were used to estimate deposition rates. Limited correlation was found between wind, tides, and the TSS in the samples. When tides were near low water, a few higher TSS values were observed. Shallow depths during lower tides may have allowed the wind wave energy to reach bottom sediments and cause resuspension. Low TSS concentration during high tide can be attributed to wave action not reaching the bottom and stirring the sediment. A scale model was constructed and used to test a training structure design. The results of the testing show that basic design of the deflecting wall could be effective if it were oriented at the correct angle and at an optimum length. The east side of the entrance would be more effective at deflecting sediment-laden waters if it mirrored the west side of the entrance. The same method could be applied to the Commercial Docking Facility to alter the sharp corners in the current design. It is recommended that the Ports of Biloxi be modified in order to reduce the need for dredging. Changing the bumper design outside of the Small Craft Harbor will reduce sediment by a small amount and is a cost effective solution. Mechanical agitation will also reduce sedimentation, but operation and maintenance costs may be too high. The best solution to reduce dredging in the ports is to reconfigure the entrances to mirror the west side of the entrance to the Small Craft Harbor. Constructing a current deflecting wall in addition to this design will sustain water quality while directing sediment away from the ports. Further design and modeling of the port entrances will need to be conducted before construction.