GEOLOGY AND GROUND-WATER RESOURCES OF THE LAWRENCEVILLE AREA, GEORGIA By Melinda J. Chapman, Thomas J. Crawford, and W. Todd Tharpe U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 98-4233 Prepared in cooperation with the CITY OF LAWRENCEVILLE, GEORGIA Atlanta, Georgia 1999 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. For additional information write to: Copies of this report can be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Branch of Information Services 3039 Amwiler Road, Suite 130 Box 25286 Peachtree Business Center Federal Center Atlanta, GA 30360-2824 Denver, CO 80225 CONTENTS Abstract.......................................................................................................................................................................................1 Introduction ...............................................................................................................................................................................2 Background.......................................................................................................................................................................2 Purpose and scope ............................................................................................................................................................4 Description of the study area............................................................................................................................................4 Methods of investigation ..................................................................................................................................................5 Previous studies ................................................................................................................................................................5 Well and surface-water station numbering systems..........................................................................................................7 Acknowledgments ............................................................................................................................................................7 Regional geology .......................................................................................................................................................................7 Geologic mapping—interpretations and limitations.........................................................................................................7 Lithologic units ................................................................................................................................................................8 Amphibolite ...........................................................................................................................................................8 Biotite gneiss .........................................................................................................................................................8 Button schist ...........................................................................................................................................................9 Granite gneiss ........................................................................................................................................................9 Magnetite quartzite.................................................................................................................................................9 Quartzite and aluminous schist...............................................................................................................................9 Diabase dikes........................................................................................................................................................10 Hydrogeologic sections .................................................................................................................................................10 Ground-water resources ...........................................................................................................................................................12 Well inventory and data compilation .............................................................................................................................12 City of Lawrenceville historical well records ......................................................................................................12 Well yields ............................................................................................................................................................12 Relation of well yield to lithology .................................................................................................................................13 Amphibolite .........................................................................................................................................................13 Biotite gneiss .......................................................................................................................................................16 Button schist ........................................................................................................................................................16 Granite gneiss .......................................................................................................................................................17 Quartzite and aluminous schist ............................................................................................................................17 Interpretation of borehole geophysical logs ..................................................................................................................17 Rhodes Jordan Wellfield.......................................................................................................................................20 Maltbie Street well................................................................................................................................................21 Pike Street well.....................................................................................................................................................21 Gwinnett County Airport well..............................................................................................................................28 Analyses of ground-water levels.....................................................................................................................................28 Response of local ground-water levels to pumpage .............................................................................................29 Areal effects of ground-water withdrawals .........................................................................................................34 Ground-water quality......................................................................................................................................................34 Summary and conclusions .......................................................................................................................................................45 References cited .......................................................................................................................................................................45 Contents iii ILLUSTRATIONS [Plates are in pocket in back of report] Plate 1. Lithologic map showing the distribution of major rock types, fault contacts, and well locations in the Lawrenceville area, Georgia 2. Hydrogeologic sections showing general dip of lithologic units inferred from surface geologic mapping and subsurface lithologic and fracture data collected from wells in the Lawrenceville area, Georgia Figure 1. Map showing location of (A) the study area in Gwinnett County and physiographic provinces in Georgia, and (B) the Rhodes Jordan Wellfield and observation wells in Lawrenceville, Georgia........................................................................................................................ 3 2. Subsurface lithologic characteristics and fractures penetrated by wells 14FF08, 14FF26, 14FF27, and 14FF42.............................................................................................................................. 18 3. Fracture identification and relative comparison of fractures in Rhodes Jordan Wellfield well 14FF16 using borehole geophysical logs....................................................................................... 22 4. Fracture identification and relative comparison of fractures in Maltbie Street well 14FF08 using borehole geophysical logs ............................................................................................................ 24 5. Fracture identification and relative comparison of fractures in Pike Street well 14FF27 using borehole geophysical logs ............................................................................................................ 26 6. Fracture identification and relative comparison of fractures in Gwinnett County Airport well 14FF42 using borehole geophysical logs......................................................................................