Research about Orlando, Florida

USGS1978

Preliminary appraisal of the geohydrologic aspects of drainage wells, Orlando area, central Florida

The Floridan aquifer contains two highly transmissive cavernous zones in the Orlando area: an upper producing zone about 150-600 feet below land surface; and a lower producing zone about 1,100-1,500 feet below land surface. Natural head differences are downward and there is hydraulic connection between the two producing zones. Drainage wells are finished open-end into the upper producing zone and emplace surface waters directly into that zone by gravity. Quantitatively, their use constitutes an effective method of artificial recharge. Their negative aspects relate to the probably poor, but unknown, quality of the recharge water. Caution is suggested in drawing definite and final conclusions on the overall geohydrologic and environmental effects of drainage wells prior to the collection and interpretation of a considerable quantity of new data. Though few ground-water pollution problems have been documented to date, the potential for such pollution should be seriously considered in light of the prob-able continuing need to use drainage wells; the probable volumes and quality of water involved; and the hydraulic relations between the two producing zones.

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USGS1946

Artificial recharge of artesian limestone at Orlando, Florida

The principal aquifer in the Orlando area consists of 900 feet or more of permeable artesian limestones of upper and middle Eocene age. As in most other parts of the Florida peninsula, these limestones are overlain by the Hawthorn formation of Miocene age which contains relatively impervious beds. The Hawthorn at Orlando is 45 to 200 feet thick and prevents or retards natural recharge to the lime. stones except where it is penetrated by what appear to be old sinkholes that are now filled with pervious material. Owing to the lack of adequate surface drainage, more than 200 wells have been drilled into the limestones in the Orlando area to drain streets, control lake levels, and dispose of sewage and other waste liquids. Generally the piezometric surface of the water in the limestones is fat enough below the land surface to allow drainage by gravity. As the limestones are cavernous, most of the wells have large capacities for receiving water and seldom become clogged although a considerable amount of rubbish is carried into them. The piezometric surface is conspicuously higher where drainage wells are concentrated, probably because of recharge through wells. However, the effect of the artificial recharge cannot be clearly differentiated from that of natural recharge. A deep-well current meter was used to determine the horizons at which the polluted surface water enters the limestones. The investigation was made in cooperation with the Florida Geological Survey and the Corps of Engineers of the U.S. Army.

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