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Revised Hydrogeologic Framework of the Floridan Aquifer System in the Northern Coastal Area of Georgia and Adjacent Part

Revised Hydrogeologic Framework of the Floridan Aquifer System in the Northern Coastal Area of Georgia and Adjacent Parts of South Carolina. L.J. Williams and H.E. Gill* U.S. Geological Survey Atlanta, GA September, 24, 2010. *Hydrologist, USGS Ret. SIR 2010-5158.

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Revised Hydrogeologic Framework of the Floridan Aquifer System in the Northern Coastal Area of Georgia and Adjacent Part

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  1. Revised Hydrogeologic Framework of the Floridan Aquifer System in the Northern Coastal Area of Georgia and Adjacent Parts of South Carolina L.J. Williams and H.E. Gill* U.S. Geological Survey Atlanta, GA September, 24, 2010 *Hydrologist, USGS Ret.

  2. SIR 2010-5158 • Revises the Hydrogeology for 8 coastal counties in Georgia and 5 coastal counties in South Carolina • Supersedes the USGS RASA Framework completed in the 1980’s

  3. Acknowledgments • David Prowell, USGS, Emeritus • Consolidated Utilities, City of Richmond Hill City of Rincon • Carter and Sloope, Inc. • SCDNR, SCDHEC • Fred Falls, USGS, South Carolina • Bob Faye, USGS, Retired • Many others….

  4. Study Area Floridan Aquifer System

  5. Study Area • 8 coastal counties in Georgia • 5 coastal counties in South Carolina

  6. Floridan Aquifer System SURFICIAL AQUIFER UPPER CONFINING UNIT (clay) UPPER FLORIDAN AQUIFER MIDDLE CONFINING UNIT LOWER FLORIDAN AQUIFER SALINE WATER

  7. Problem: very few wells tapped the full thickness of the FAS during the original RASA study

  8. Biggest unknown: position of the MCU SURFICIAL AQUIFER UPPER CONFINING UNIT (clay) UPPER FLORIDAN AQUIFER ? ? MIDDLE CONFINING UNIT LOWER FLORIDAN AQUIFER SALINE WATER

  9. Today: many more wells are available

  10. Revised Hydrogeology of the Floridan Aquifer System • Hydrologic data from key well sites • Updated Maps for • Top of Upper Floridan • Top of Middle Confining Unit • Top of Lower Floridan • Base of Lower Floridan • Thickness, extent, hydraulic properties of aquifers • Cross-sections • Aquifer Interconnection • Regional Correlation

  11. Key Wells

  12. Methods • Compiled flow-zone data from current-meter (flowmeter) test wells • Evaluated electric logs for “invasion profiles” • Constructed cross-sections and evaluated stratigraphic position of water-bearing zones

  13. Flowmeter Data:McCollum and Counts, 1964

  14. Flowmeter Data: New Wells Harris Trail Well, Richmond Hill, GA

  15. Electric Logs and Invasion Profiles Hawthorne Suwannee Invasion profiles Ocala Seismic Hole #3, Effingham Co. Georgia (Mudded hole)

  16. Geophysical Markers Used for Mapping • ‘C’ approximates the top of Oligocene • ‘D’ approximates the top of Upper Eocene rocks A B Top of Floridan Aquifer System C Oligocene Rocks D Upper Eocene Rocks Skidaway Island

  17. Key Well Sites Optical Televiewer Image • Hunter Army Airfield • Berwick Plantation • Richmond Hill • Pineora • Rincon • Gillsonville • And more…

  18. Cross Sections: What connects to what? Skidaway Island Berwick Plantation Hunter Army Airfield

  19. Evaluated Flow Zones in Relation to Hydrologic Units Hunter Army Airfield Lower Floridan Test Well, 2009

  20. (2002) (2009) (2000)

  21. Berwick Plantation Lower Floridan Well 2002

  22. (1996) (1999) (1999) (corehole, 2009) (1986)

  23. LF mapping horizon Stratigraphic correlation by Prowell, 2009

  24. Logs from Pineora Corehole, 2009 Upper Floridan top of middle Eocene Rocks LF mapping horizon Falls LF Lower Floridan

  25. GillsonvilleCorehole (JAS-426) Upper Floridan top of middle Eocene Rocks LF mapping horizon Lower Floridan base of Floridan Aquifer System base of Floridan Aquifer System

  26. (2002) (2009) (2000)

  27. Flowmeter Logs -- HAAF • 3 major water zones in UFA • 1 zone in confining bed • confining bed 550’ and 710’ • 4 water zones in LFA

  28. Pump Discharge 847 gal/min with ~ 6 ft drawdown 847

  29. Flowmeter Types Electromagnetic Flowmeter • Spinner • 20 to >1000 gal/min • Electromagnetic • 1 to > 1000 gal/min • Heat-pulse • <2 gal/min Heat Pulse Flowmeter Spinner Flowmeter

  30. Upflow in gpm BOREHOLE Upflow in gpm Depth, in feet Measured

  31. BOREHOLE Upflow in gpm Upflow in gpm Depth, in feet Measured

  32. BOREHOLE Upflow in gpm Upflow in gpm Depth, in feet Measured

  33. BOREHOLE Upflow in gpm Upflow in gpm Depth, in feet Measured

  34. BOREHOLE Upflow in gpm Upflow in gpm Depth, in feet Measured

  35. BOREHOLE Upflow in gpm Upflow in gpm Depth, in feet Measured End movie

  36. INTERPRETATION Inflow Inflow Inflow Upflow in gpm

  37. Middle Confining Unit – How do you define top and bottom?

  38. Hunter Army Airfield Lower Floridan Well 2009 83.5% 4.3% 12.3%

  39. Flowmeter for Hunter Army Airfield Lower Floridan Well Top of Confining Bed Middle Eocene Rocks Bottom of Confining Bed Lower Floridan mapping horizon Packer Test

  40. Revised Hydrostratigraphy Updated Not Updated Surficial aquifer Top of Upper Confining Unit • Top of Upper Floridan • Top of ‘D’ Marker • Top of Middle Confining Unit • Top of Lower Floridan • Thickness of • Upper Floridan • Middle Confining Unit • Lower Floridan • Base of System • Lower Brunswick

  41. STRIKE DIP

  42. Revised Hydrogeology Conforms Better to Stratigraphy Dip Section showing stratigraphic control on water-bearing zones in Lower Floridan Aquifer

  43. Mapping Horizons

  44. Top of Floridan Aquifer System (geophysical marker ‘C’)

  45. Top of Permeable part of FAS (geophysical marker ‘D’)

  46. Base of Upper Floridan(top of middle confining unit)

  47. Top of Lower Floridan STRIKE DIP Top of Middle Eocene (Miller, 1986)

  48. Top of Lower Floridan Comparison • New Interpretation • PP 1403B

  49. Middle Confining Unit • Fairly consistent thickness throughout area • Thickest in the Hilton Head Island area

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