WELL CONSTRUCTION, LITHOLOGY, AND GEOPHYSICAL LOGS FOR BOREHOLES IN BEAR CREEK VALLEY NEAR OAK RIDGE, TENNESSEE by Zelda Chapman Bailey and Dorothea Barrows Withington U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 88-4068 Prepared in cooperation with the DEPARTMENT OF ENERGY Nashville, Tennessee 1988 DEPARTMENT OI THE INTERIOR DONALD PAUL MODEL, Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director For additional information write to: Copies of mis report can be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Books and Open-File Reports Section A-413 Federal Building Federal Center, Bldg. 810 U.S. Courthouse Box 25425 Nashville, Tennessee 37203 Denver, Colorado 80225 CONTENTS Abstract 1 Introduction 1 Geologic setting 3 Acknowledgments 3 Well construction 3 Well locations and general lithology 7 Lithology 7 Boreholes at the base of Chestnut Ridge 13 Boreholes along Pine Ridge 14 Geophysical logs 14 Boreholes at the base of Chestnut Ridge 16 Boreholes along Pine Ridge 19 Summary 20 References cited 21 PLATES (in pocket) 1. Diagrams showing comparison of zones delineated from lithologic samples and from geophysical logs 2-7. Diagrams showing well construction, combined zones, and geophysical logs for well: 2. GW-230 at site 2UT 3. GW-232 at site 2E 4. GW-239 at site 2W 5. GW-214atsite3S 6. GW-208 at site 4E 7. GW-211atsite4W ILLUSTRATIONS 1. Map showing study area and drilling-site locations 2 2. Map showing bedrock geology of study area 4 3. Generalized geologic section through Bear Creek Valley 5 4-8. Maps showing well locations and geology at sites: 4. IN and IS 8 5. 3N and 3S 9 6. 4E and 2W 10 7. 2Eand2UT 11 8. 4W 12 9. Photograph showing examples of structure observed on acoustic-televiewer logs 17 TABLES 1. Construction and locations of wells and test holes 6 2. Geophysical logs made in boreholes in Bear Creek Valley 15 FACTORS FOR CONVERTING INCH-POUND UNITS TO THE INTERNATIONAL SYSTEM OF UNITS <SD Multiply by To obtain inch (in.) 25.4 millimeter (mm) foot (ft) 0.3048 meter (m) gallon per minute (gal/min) 3.785 liter per minute (L/min) To convert degree Fahrenheit (°F) to degree Celsius (°C) (0.556) ("F -32 ) = °C Sea level: In this report "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929) a geodetic datum derived from a general ad­ justment of the first-order level nets of both the United States and Canada, formerly called "Mean Sea Level of 1929." The use of trade, product, industry, or firm names in this report is for iden­ tification or location purposes only, and does not constitute endorsement of products by the U.S. Geological Survey, nor impute responsibility for any present or potential effects on the natural resources. IV WELL CONSTRUCTION, LITHOLOGY, AND GEOPHYSICAL LOGS FOR BOREHOLES IN BEAR CREEK VALLEY NEAR OAK RIDGE, TENNESSEE by Zelda Chapman Bailey and Dorothea Barrows Withington ABSTRACT INTRODUCTION Twenty-four wells were constructed at nine The U.S. Geological Survey, in coopera- sites in Bear Creek Valley to provide geologic tion with the U.S. Department of Energy and hydrologic information. Lithologic samples (DOE), is conducting a hydrogeologic study of and suites of geophysical logs were obtained Bear Creek Valley in the Oak Ridge Reserva- from the deepest boreholes at six of the sites, tion, Tennessee. The purpose of the study is to Two of these boreholes at the base of Chestnut describe the ground-water flow system and Ridge were completed in the Maynardville determine the potential extent of contaminant Limestone and two were completed in the migration. Observation wells were drilled at Nolichucky Shale. Two boreholes along Pine nine sites (fig. 1) around the perimeter of the val- Ridge were completed in the Rome Formation, ley to provide information on lithology, geologic structure, and hydrologic boundaries of the Zones of similar lithology within a ground-water flow system. Wells at two of the borehole were delineated from rock cuttings and sites were drilled by contractors to DOE; the refined by examination of geophysical logs. The remaining wells were drilled by the Geological contact between the Maynardville Limestone Survey and the U.S. Army Corps of Engineers, and Nolichucky Shale was identified in two of the Mobile District. Geophysical logs were obtained boreholes. Fractures and cavities were readily in six of the boreholes. Drilling began in Octo- identifiable on the acoustic-televiewer and ber 1985 and drilling and logging were com- caliper logs. Distinct water-bearing intervals pleted in May 1986. were also identified from the temperature, fluid resistance, and resistivity logs. Depths at which the drilling encountered a thrust fault were iden- The purpose of this report is to provide tifed in two boreholes in the Rome Formation information on well locations and construction, from both rock cuttings and from geophysical and on interpretations made from lithologic logs. samples and geophysical logs. OAK RIDGE OAK RlD | UNIVERSITY OF .IC« O-IM BOTTR/p ,-p-<^ USfiS-4F USGS-3N \ I * h Y - -^/ 3X TENNESSEE STUDY PINE RIDGE USGS-4W /If FORESTRY Y 2L:« .... T , | 1 EXPERIMENT BEAR CREEK [CLINCH RIVER \:^: f-^ftiS:"aSlv-^' . \ USGS-2 1 STATION Bear gi 0USGS- 1S USGS.2W£i)r- JJ-USGS-2UT USGS-3S CHESTNUT \' RIDGE *.- 1 J(?0 fTENNFSSFF VALLEY S °°' AUTHORITY WATTSJ BAH HESEHVO1R 1 k^ S RESERVATION I , :,.,,,.,,.:^ .,: . ... 'Stail.^S^,,,..:,.,:.:,,, ,,.$:, EXPLANATION Study area A A' Line of geologic section Drilling site and designation USGS-1N 3 MILES TENNESSEE Figure 1. Study area and drilling-site locations. E 60,000 E 70,000 E 10.000 E 20,000 E 30,000 E 40,000 N 30,000 Geology modified from and A.B. Hoos and Z.C. Bailey, 1986, and W.M. McMaster 1963 EXPLANATION §0 Copper Ridge Dolomite Maynardville Limestone 3 MILES Nolichucky Shale DC I Maryville Limestone CQ Rogersville Shale and (4)<OCzo o Rutledge Limestone o (5)° Pumpkin Valley Shale Rome Formation Geology undifferentiated Approximate geologic contact Thrust fault Drilling site Coordinates relate to Tennessee Valley Authority S-16A grid system June 1974 Figure 2. Bedrock geology of study area. Geologic Setting vision of drilling operations was provided by David A. Webster, and assistance in geophysical Bear Creek Valley and adjacent ridges are log interpretation by Patrick Tucci, both of the underlain by rocks of Cambrian age (fig. 2) that U.S. Geological Survey, strike approximately north 55 degrees east. The dip of the rock varies from 30 to 70 degrees to the southeast, but the average dip is about 45 degrees WELL CONSTRUCTION (fig. 3). A series of thrust faults, also dipping southeast, intersect the northwest flank of Pine Nine sites (fig. 1) were selected and three Ridge. Pine Ridge is underlain by interbedded wells were to be drilled at each site to provide sandstone, siltstone, and shale of the Rome For- vertical hydraulic-potential data: one shallow mation. Bear Creek Valley is underlain by six well in the regolith, and two wells in bedrock at formations that compose the Conasauga Group, about 100 and 400 feet in depth. Problems en- From oldest to youngest these formations are: countered during drilling resulted in one' site Pumpkin Valley Shale, Rutledge Limestone, having only one well and two sites having Rogersville Shale, Maryville Limestone, boreholes drilled that had to be abandoned. A Nolichucky Shale, and Maynardville Limestone, total of 24 wells were constructed and an addi- The Maynardville Limestone contains solution tional 3 boreholes were drilled but wells were not cavities. Chestnut Ridge is underlain by massive, installed. Drilling-site names and well names siliceous dolomite of the Knox Group and con- were assigned from a naming system used by tains solution and karst features. The Copper MMES staff for wells in Bear Creek Valley. Fol- Ridge Dolomite is the oldest formation in the lowing are general descriptions of drilling, Knox Group and overlies the Maynardville casing, and grouting procedures. Location coor- Limestone. Regolith, consisting of soil and dinates and specific construction information for weathered rock, overlies the bedrock and ranges each well and test hole are summarized in from 0 to 80 feet thick. table 1. Holes for the shallow wells were augered to Acknowledgments the top of bedrock. A 2-inch PVC casing with 5 feet of slotted PVC screen at the bottom was in- The assistance and contributions of several stalled in each hole. Sand was poured into the people were particularly valuable to the project annulus around the screen to about 1 foot above and are greatly appreciated. Dr. C. Stephen the top of the screen, and a 1-foot deep layer of Haase and George Gillis, Martin Marietta Ener- bentonite pellets was poured into the annulus to gy Systems, Inc. (MMES), provided the drilling form a seal. A Portland Type 1 cement slurry was for five wells at two of the drilling sites, logisti- then poured into the annulus around the casing cal support during the Geological Survey drill- to form a seal from the top of the bentonite to ing, and surveying for grid coordinates and ground surface, elevations of the wells. In addition to drilling on DOE property, permission was granted by Ten- Holes for the deeper wells were first nessee Valley Authority and University of Ten- augered to the top of bedrock and 8-inch nessee to drill and collect data on their diameter PVC surface casing was grouted into properties. Geophysical logging was conducted the holes to seal water and surface material out by Gerald E. Idler, U.S. Geological Survey, who of the borehole during drilling. The underlying provides logging services for the Southeastern bedrock was then drilled by either air hammer or Region.