Evaluation and Cost Comparison of Anti-Siltation Systems and Traditional Dredging Methods

摘要

Maintaining the design depth of ship servicing facilities is a challenging task. Dredging technology has improved significantly in the past few decades and this should have driven the cost downwards. However, increased environmental awareness has placed limitations on how dredge spoils are handled, transported and disposed of and has effectively increased the costs of dredging operations. The United States Army Corps of Engineers and the Naval Facilities Engineering Command have conducted research into alternate sediment removal methods that may replace conventional dredging in sites where the conditions merit. The alternate systems include arrays of jets to prevent settling of suspended sediment and systems to entrain and transport sediment without physical removal. This study investigates the most promising techniques researched by the United States Army Corps of Engineers and the Naval Facilities Engineering Command for application at Naval Station Mayport, Florida. Naval Station Mayport has a long history of high sedimentation rates and difficulty in maintaining design depths at the piers, despite several studies to determine cost effective alternatives. Although several conservative assumptions were made concerning environmental conditions at the site that directly affect the design concept presented, the economic analysis indicated substantial saving can be realized if an alternate system consisting of turbo scouring units and a catchment basin were installed. The analysis takes into consideration the initial capital cost and the annual operation and maintenance of the alternate system for a 30-year life cycle, adjusted for inflation and compares the total cost against the cost to continue the current dredging operations at the existing frequency and quantities.