Cape Sable Canals Dam Rehabilitation Environmental Assessment
The National Park Service (NPS) has issued a Finding of No Significant Impact (FONSI) for the Cape Sable Canals Dam Restoration project. Southeast Regional Director David Vela approved the FONSI based on the environmental assessment (EA) recommended by Everglades National Park Superintendent Dan B. Kimball. With the National Environmental Policy Act process completed, the Park can now focus on implementing this important American Reinvestment and Recovery Act (ARRA) project.
The NPS is planning to use approximately $12 million of ARRA funds to replace the failed dams on the East Cape Extension and Homestead Canals within the Cape Sable area of the Park. The new canal plugs will provide sustainable solutions to issues associated with saltwater intrusion in and degradation of freshwater and brackish marshes north of the Cape Sable marl ridge, illegal motorized boat access into the Marjory Stoneman Douglas Wilderness area, and unsafe conditions for motorized and non-motorized boaters at the dam sites.
Strong public and agency involvement played an important role in developing the alternatives and environmental assessment for this project. The approved FONSI is based on Alternatives D and D1, identified as the Preferred Alternatives, when the EA was released for public review and comment June 14 through July 14, 2009.
The selected alternative for the East Cape Extension Canal dam is Alternative D. Under this scenario, two sheetpile walls will be constructed approximately 100 feet apart. The area between the walls will be filled and planted with native vegetation to reduce the potential for erosion. Landward sheetpile wingwalls will be installed to deflect sheetflow away from the dams. Riprap will also be placed along the wingwalls and exposed canal banks to provide erosion resistance.
The selected alternative for the Homestead Canal dam is Alternative D1. The plug will be constructed by installing two sets of geotubes approximately 100 feet apart. The area between the geotubes will be filled and planted with native vegetation to reduce the potential for erosion. Riprap will be used along exposed canal banks to provide erosion resistance.
Under both alternatives, the dams will function for a 50-year life-cycle, the natural and cultural resources will be protected and the safety hazards from the existing dam structures will be removed resulting in a positive visitor experience. The plugs will also help to prevent illegal motorized boat entry into the wilderness area. A portage will be installed to provide safe passage over the restored dams for non-motorized boaters (canoeists/kayakers).
The Park is initiating a detailed planning and design phase and will apply for required environmental permits from the U.S. Army Corps of Engineers, the South Florida Water Management District, and the Florida Department of Environmental Protection. This phase of the project will occur beginning August, 2009 to Spring 2010. Staging for the project will commence in summer 2010, and construction of the canal plugs is scheduled to begin October 1, 2010 and conclude by March 31, 2011 so as not to interfere with crocodile nesting season from April through September.
The FONSI and EA are available by clicking on the "Document List" link on this page, or through the Everglades National Park website: www.nps.gov/ever. Scroll down to the Cape Sable Canals Dam Restoration element and follow the links to download or view the documents. For more information about the Cape Sable Canals Dam Restoration, contact Dewitt Smith, Project Manager at 305-224-4218, or Linda Friar at 305-224-7714
Thank you for taking the time to assist us in this planning process. Your interest and participation in the future of Everglades National Park is greatly appreciated.
Dan B. Kimball
DeWitt Smith (305) 224-4218
Linda Friar (305) 242-7714
Dear Friends of Everglades National Park: