Webb, Frederick J., Jr. (ed.) / Proceedings of the 13th Annual Conference on Wetlands Restoration and Creation, May 15-16, 1986
Rushton, Betty T.
Cypress swamp regeneration: a reclamation alternative for wet depressions in clay settling ponds, pp. 148-163 PDF (5.3 MB)
industry in central Florida. Typically one ton of clay waste (dry weight) is produced for each ton of phosphate rock. The clays expand to many times their original volume in the mining process and require large above-ground storage impoundments ranging from 160 to 325 ha surrounded by earth dams from 7 to 20 meters in height. Approximately 50 to 70 percent of the land proposed for mining is designated for clay settling areas. Reclamation of clay impoundments is mandated by Florida state law, which requires restoration of all lands disturbed by phosphate mining after July 1, 1975. Since phosphatic clays have poor load bearing capacity, possibilities for productive use following mining are limited. Most reclamation projects have converted clay ponds to pasture. In Florida, a state with a long, colorful history of drainage projects, interest in saving wetlands has increased steadily over the past decade culminating in the passage of the Warren S. Henderson Wetland Protection Act of 1984. Mitigation by restoration of wetlands could replace swamps being lost by current and past land use practices. Cypress swamps, which occur throughout the southeastern United States, are especially common in Florida, where they form lake fringes, strands, and domes. Clay settling ponds provide an opportunity to restore cypress forest to the post mining landscape. STUDY SITES Seven clay settling ponds representing different ages and reclama- tion techniques were planted during the winter of 1984-85. The locations are shown on the map in Figure 1 and summary information is listed in Table 1. CF Industries used a sand/clay mix for clay disposal at their Hardee mining complex. This site was abandoned as an active clay pond in 1983. Trees were planted along the edge of a seasonally flooded pond. Gardinier, Area A, located at the Ft. Meade mine was ditched, drained, and the dikes lowered in 1975. Outfall pipes are now above the level of the clays providing drainage only during extremely high water. Trees were planted in the wetter lower end which had been submerged for the past year. During the early establishment phase, however, a drought and subsequent fire caused considerable mortality. Tenoroc, Area 4A, is a large clay settling pond located in a State Reserve under the jurisdiction of the Department of Natural Resources. The west end, where most of the trees were planted was mined and has many spoil piles protruding above the clay surface. Three transects are located on the edge of an intermittent pond. Four drier transects were planted in willows growing at the northwest corner. IMC-H9 is a reclamation project for International Mineral and Chemical Corp. In 1985 it already had healthy, well-established 4 to 5 149
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