Geohydrology and potential for upward movement of saline water in the Cocoa well field, East Orange County, Florida

Abstract

Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times foot of aquifer thickness [(ft 3 /d)/ft 2 ]ft. In this report, the mathematically reduced form, foot squared per day (ft 2 /d), is used for convenience. Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25 ˚C).

Hydrogeologic conditions and simulation of ground-water flow in the Greater Orlando Metropolitan Area, East-Central Florida

“…Leakance values derived from this test range from lxlO"5/d to lxlO"3/d, bracketing the value of 5xlO"5/d used in the RASA model. Recent USGS aquifer tests conducted at the Cocoa well field indicate that the middle semiconfining unit can be highly anisotropic (Phelps and Schiffer, 1996). The vertical hydraulic conductivity of a 6-ft section of the unit was estimated to be no greater than 5x10~2 ft/d, whereas the horizontal hydraulic conductivity was estimated at 20 ft/d.…”

“…Another possible source of this brackish water is a local pocket of entrapped relict seawater that exists near or below pumping wells. Water-quality data collected during recent test drilling at the Cocoa well field indicate that fresh and saltier (relict) water may be layered within the Upper Floridan aquifer, possibly the result of fluctuating sea levels over geologic time (Phelps and Schiffer, 1996). Lateral intrusion of brackish water from the east is also a potential source of brackish water at the well field.…”

“…Increased chloride concentrations at Cocoa C probably result from the local movement of brackish water laterally from the east part of the well field. A more detailed discussion of water-quality conditions in the Floridan aquifer system at the Cocoa well field is provided by Phelps and Schiffer (1996).…”