Maintenance dredging, Matagorda Ship Channel, Texas: final environmental statement
United States Army Engineer District, Galveston, TX
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The Matagorda Ship Channel is a Federal navigation project in Calhoun and Matagorda Counties, Texas, with a deep-draft portion extending from deep water in the Gulf of Mexico through Matagorda Bay and Lavaca Bay to a turning basin near the Aluminum Company of America plant (Alcoa) at Point Comfort. The deep-draft channel was authorized by the River and Harbor Congress, Second Session. The channel in Matagorda and Lavaca Bays is 36 feet deep, 200-300 feet wide and 22 miles in length; the turning basin at Alcoa is 36 feet deep and 1,000 feet square; the entrance channel is 38 feet deep, 300 feet wide, and 3.2 miles in length. Two shallow-draft branch channels, 12 feet deep and 125 feet wide, serve Port Lavaca and the Harbor of Refuge. A third shallow-draft channel, 6 feet deep, 100 feet wide, and 20.2 miles in length, traverses Lavaca Bay and extends up the Lavaca and Navidad Rivers into Jackson County. The Gulf Intracoastal Waterway (GIWW) crosses the deep-draft channel near mile 3. Figure 1 is a map showing the channel layout and the project area. The proposed plan of action call for continued maintenance of the deep-draft channel and the tributary shallow-draft channels to insure sufficient carrying capacity in the channels for the efficient movement of commercial navigation. The proposed work will also decrease chances of vessel collisions and groundings which could be extremeful harmful to the human and marine environments of Matagorda and Lavaca Bays. A serious accident releasing significant quantities of petroleum or chemicals could result in adverse environmental impacts and public health hazards. Although there are numerous pipelines crossing the various project channels, there should be no danger of such pipelines being damaged or ruptured during dredging. Construction of such pipelines is controlled by the Corps of Engineers permit program, and all pipelines must be constructed a minimum of 5 feet below the maximum depth dredged. In addition, the locations of all such pipelines are clearly marked on construction plans, and dredging in the vicinity of a pipeline is performed in such a manner to avoid placing anchors or spuds near the pipeline.