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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
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