clays. The slurries are then piped up to several kilometers to industrial beneficiation
plants that separate the extracted clay soil matrix through a process of washing and
settling of the sands and silts. This process separates the slurry into phosphate product,
sand tailings, and phosphatic clay slimes. The byproducts are then disposed of
throughout the mined landscape.

 The three main environments receiving beneficiation byproducts are clay settling
ponds, overburden soil pits, and sand tailings. Clay settling ponds occupy 60-70% of the
mined landscape (Rushton 1988), forming expansive wetlands and open water areas
surrounded by earthen dams. The typical size of a clay settling pond is 2.5 km2.
However, clay settling ponds are an impermanent system designed to dry out
waterlogged clays. The water content remains high in the clays for years, drying out
gradually through pan evaporation and transpiration (Zellars-Williams and others 1980).
Without human intervention, this drying process may take 10-20 years (Maehr 1984).
For a more complete study of wetland succession on abandoned clay settling ponds see
Rushton (1983).

 Overburden soil pits make up approximately 10-25% of the total land holdings
and are a direct consequence of digging by draglines (FDE 1984). These areas are
characterized by narrow, steep upland mounds surrounded by water bodies commonly
filled with effluent from the industrial beneficiation of the mined phosphate. This water
often comes in direct contact with ground water.

 The remaining byproducts are the sand tailings, which are settled out in the
industrial beneficiation process. After beneficiation, sand tailings are left nutrient poor.
Because of low nutrient levels, sand tailings are difficult to vegetate (Zellars-Williams
and others 1980) and are often used as reclamation fill or simply stacked in large piles on
the mined landscape.


6A-4