The wastes are injected into the lower part of the carbonate Fioridan aquifer, which is extremely permeable and cavernous (see Fig. 14.15). The natural direction of ground- water flow is to the southeast. The confining layer is 150 ft of dense carbonate rocks. The chloride concentration in the upper part of the injection zone is 1,650 mg/L, increasing to 15,800 mg/L near the bottom of the formation (101). The sources used for this case study did not provide any data on the current injection zone. The native fluid was basically a sodium- chloride solution but also included significant quantities of sulfate (1,500 mg/L), magnesium (625 mg/L), and calcium (477 mg/L).