Introduction 1 Purpose and scope 1 Physiographic and geologic setting 2 Hydrogeology of parts of Pinellas County 4 Surficial aquifer system 4 Intermediate confining unit 5 Floridan aquifer system 5 Zone A 5 Semiconfining unit between zones A and B 6 Zone B 7 Water-quality data 8 Potential for development of brackish groundwater resources 8 Simulation of the effects of development on the quality of ground water Model approach and limitations 9 Boundary conditions 12 Input parameters 12 Finite-difference methods 13 Model results and sensitivity analysis 14 Solute concentration distribution 14 Pumping rates 15 Hydraulic conductivity of the lower semiconfining unit 15 Intermediate confining unit thickness 15 Porosity 15 Dispersivity 16 Boundary conditions 16 Partially penetrating wells 16 Feasibility of developing the brackish groundwater resources 18 Summary and conclusions 18 Selected references 19 FIGURES 1. Map showing location of study area 2 2. Generalized stratigraphic and hydrogeologic section, Pinellas County 3 3-7. Maps showing: 3. Thickness of the surficial aquifer system, Pinellas County 4 4. Thickness of the intermediate confining unit, Pinellas County 5 5. Top of permeable zone A of the Upper Floridan aquifer, Pinellas County 6 6. Bottom of permeable zone A of the Upper Floridan aquifer, Pinellas County 7 7. Thickness of permeable zone A of the Upper Floridan aquifer, Pinellas County 7 8. Graph showing relation between chloride and dissolved-solids concentrations in water from selected wells in Pinellas County 10 9-12. Maps showing: 9. Estimated concentration of dissolved solids in water from selected wells open to permeable zone A of the Upper Floridan aquifer, Pinellas County 10 10. Location of well fields in Pinellas County 11 11. Differences in water levels in wells completed in the surficial aquifer system and the Upper Floridan aquifer, September 1981 (wet-season conditions) 11 Contents III
