Permeable zones Floridan aquifer

The wastes are injected into the lower part of the carbonate Floridan aquifer, which is extremely permeable and cavernous. The natural direction of groundwater flow is to the southeast. The confining layer is 45 m (150 ft) of dense carbonate rocks. The chloride concentration in the upper part of the injection zone is 1650 mg/L, increasing to 15,800 mg/L near the bottom of the formation.172 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 (1500 mg/L), magnesium (625 mg/L), and calcium (477 mg/L). 

Table 1.—Water levels and head differences between the water table and the two permeable zones in the Upper Floridan aquifer [WT = water table UPZ upper permeable zone ...

Based on a comparison of the head differences shown in Table 1, the degree of hydraulic separation is much greater between the upper and lower permeable zones in the Upper Floridan aquifer than between the upper permeable zone and the water-table aquifer. 

The small head differential, exhibited throughout the year, between the water-table aquifer and the upper permeable zone indicates that although the residuum acts as a confining unit for the Upper Floridan aquifer, vertical leakage does occur through the base of the residuum, and there is some degree of hydraulic connection between the two hydrologic zones. 

The water-table aquifer is hydraulically connected to the upper permeable zone of the Upper Floridan aquifer, and water infiltrates through the residuum to recharge the upper permeable zone. 

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