ABSTRACT

Most of the coastal wetlands in Louisiana are a result of the Mississippi River delta building process. However, this deltaic building process has been reversed in recent history through the complex interaction of physical, chemical, biological, and human activities. Human activities include agriculture, urban expansion, flood control (i.e., levee construction), as well as canal and spoil bank construction.

Louisiana contains approximately 40% of all coastal wetlands in the contiguous United States. These wetlands are highly productive and provide fertile habitat for harvest of fur bearing animals, finfish, shellfish and waterfowl. They provide numerous other public benefits, such as recreational opportunities and protection from tropical storm events. They also yield nearly one-fifth of the total U.S. oil production and approximately one-third of the U.S. natural gas production.

When oil and gas exploration began in the marshes and swamps of south Louisiana, it became important to develop an efficient means of transporting the produced hydrocarbons to processing facilities and to end users. Pipelines were designed to safely and efficiently transport these products from the production wells to the processing plants, and to fuel industrial facilities with natural gas. Pipeline construction activity in the coastal marshes has matched the level of activity in oil and gas exploration, with a slight lag between discovery and production. Pipelines have traditionally been designed within feasible economic limits, while allowing for expected future production increases.

The original project that this paper is based on was funded by a U.S. Department of Commerce Grant to the Louisiana Department of Natural Resources, Coastal Management Division (DNR CMD). This report focuses on quantifying direct impacts to wetlands relative to pipeline emplacement methods, alternative and improved pipeline emplacement technologies, and mitigation issues. The primary task in preparing this report was a literature review focusing on pipeline emplacement methods and impacts in wetland habitats. To supplement the literature search, Coastal Use Permit files for pipeline emplacement projects at the Department of Natural Resources, Coastal Management Division (DNR CMD) were researched. Interviews were also conducted with pipeline construction personnel. Current and historic infrared aerial photography, 7.5 min USGS quad maps, and habitat inventory maps were also reviewed. Finally, field visits were conducted on selected projects.