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GEOLOGICAL-GEOTECHNICAL STUDIES FOR SITING THE SUPERCONDUCTING SUPER COLLIDER IN ILLINOIS: RESULTS OF DRILLING LARGE- DIAMETER TEST HOLES IN 1986
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iiUN 1 3 ENVIRONMENTAL GEOLOGY NOTES 124
''l. STATE GEOiOfiMKiip Department of Energy and Natural Resources ILLINOIS STATE GEOLOGICAL SURVEY LIBRARY.
Vaiden, Ft. C. Geological-geotechnical studies for siting the Superconducting Super Collider in Illinois: results of drilling large-diameter test holes in 1986/ by R. C. Vaiden ... et al.—Champaign, IL: Illinois State Geological Survey, 1988.
57 p.; 28 cm. — (Environmental Geology Notes; 124) Bibliography: p. 42-44.
1. Geology— Illinois—Kane County. 2. Geology— Illinois—DuPage County. 3. Hydrogeology— Illinois—Kane County. 4. Hydrogeol- ogy— Illinois—DuPage County. 5. Geophysical exploration— Illinois,
Northeastern. 6. SSC. I. Title. II. Series.
Printed by authority of the State of Illinois 1 1988 1 1500
ILLINOIS STATE GEOLOGICAL SURVEY
3 3051 00005 5016 GEOLOGICAL-GEOTECHNICAL STUDIES FOR SITING THE SUPERCONDUCTING SUPER COLLIDER IN ILLINOIS: RESULTS OF DRILLING LARGE- DIAMETER TEST HOLES IN 1986
ILLINOIS STATE GEOLOGICAL SURVEY Morris W. Leighton, Chief
Natural Resources Building 61 5 East Peabody Drive Champaign, Illinois 61820 R. C. Vaiden M. J. Hasek C. R. Gendron B. B. Curry A. M. Graese R. A. Bauer
1988 ENVIRONMENTAL GEOLOGY NOTES 124 JUN13i
U. STATE GEOLOSMI W' Digitized by the Internet Archive
in 2012 with funding from
University of Illinois Urbana-Champaign
http://archive.org/details/geologicalgeotec124vaid CONTENTS
EXECUTIVE SUMMARY v
INTRODUCTION 1
GEOLOGIC SETTING 1
BEDROCK STRATIGRAPHY 4 Silurian System 4 Ordovician System 4 Cambrian System 5
GLACIAL DRIFT STRATIGRAPHY 5
DRILLING PROGRAM 6
GENERAL PROCEDURES 8 Sampling Procedures 9 Geophysical Logging 10 Videocamera Imaging 12 Groundwater Data 13
RESULTS 15 Geology 15 Hydrogeology 18 Spectral Gamma Ray Logs 22 Caliper Logs 22 Geotechnical Characteristics 25
TEST HOLES SSC-1 31 SSC-2 34 SSC-3 39
REFERENCES 42
APPENDIX A: Logs of Test Holes 45
APPENDIX B: Borehole Description from Closed Circuit Television 51
APPENDIX C: Geophysical Logging 55 TABLES
1 Location and approximate elevation for each test hole 7 2 Thickness of units penetrated in test hole 8 3 Characteristics of piezometers installed in each test hole 12 4 SSC observation well data (depth to water in feet below ground surface), monitored from April to December 1987 19 5 Water temperatures recorded after drilling 21 6 Laboratory logging of Rock Quality Designation (RQD) and fracture frequency of SSC-2 compared with values from adjacent Test Holes ISGS F-1, S-28, S-29 25 7 Discontinuity characterization for 4-inch core from Test Hole SSC-2 26 8 Strength and associated properties of 4-inch-diameter core from Test Hole SSC-2 27 9 Comparison of unconfined compressive strength of 4-inch and 1.8-inch cores 28 10 Average values for rock mass characteristics calculated from in situ sonic velocities 28 11 Comparison of field and laboratory compressive sonic velocities 29
FIGURES
1 Geologic map of the bedrock surface. 2 2 Stratigraphic column of bedrock and drift units in the study area north of the Sandwich Fault Zone in northeastern Illinois. 3 3 Location of all SSC drilling sites. 6 4 Comparison of selected geophysical logs from Test Hole SSC-1. 11 5 Generalized diagram of triple piezometer installation. 14 6 Concentrations of uranium (ppm) measured in geologic materials in SSC-1. 16 7 Comparison of piezometer levels with regional water levels. 20 8 Concentrations of total potassium (%) measured in geologic materials in SSC-1. 23 9 Concentrations of thorium (ppm) measured in geologic materials in SSC-1. 23 10 Stratigraphic correlations of spectral gamma ray records showing concentrations of total potassium (%), equivalent thorium (ppm), and equivalent uranium (ppm) for in situ measurements in three test holes. 24 11 Dip of fractures and joints in the Wise Lake Formation (Galena Group), Dunleith Formation (Galena Group), and Platteville Group. 29 12 Stratigraphic column of SSC-1. 32 13 Selected geophysical logs from SSC-1. 33 14 Stratigraphic column from SSC-2. 36 15 Selected geophysical logs from SSC-2. 37 16 Stratigraphic column from SSC-3. 40 17 Selected geophysical logs from SSC-3. 41 EXECUTIVE SUMMARY
The Illinois State Geological Survey (ISGS) has completed an extensive four-year study of the area near Fermi National Accelerator Laboratory (Fermilab) at Batavia, 30 miles west of Chicago. This comprehensive investigation was conducted to locate the most suitable site for construction and operation of the Superconducting Super Collider (SSC)—a 20-trillion electron volt (TeV) subatomic particle accelerator.
Illinois proposes to place the SSC below ground surface in a 10-foot-diameter tunnel about 53 miles in circumference. Underlying the proposed site in northeastern Illinois, between 250 and 600 feet deep, are the Galena and Platteville dolomites—strong, stable, nearly impermeable bedrock. To confirm that these bedrock units are suitable for construction of the SSC, ISGS geologists designed a four-year study including test drilling, rock sampling and analysis,
geophysical logging, hydrogeologic studies, and seismic exploration. Initially, the study covered parts of six counties. Subsequent research focused on successively smaller areas until the final stage of test drilling in spring 1986 concentrated on a likely corridor for the SSC tunnel.
From 1984 to 1986, thirty 3-inch-diameter test holes were drilled and more than 2 miles of bedrock core was recovered for stratigraphic description and geotechnical analysis. To supplement the information gained from the small-diameter holes, geologists drilled three 8-inch-diameter holes. The larger diameter of these holes allowed researchers to
• use geophysical tools that are standard in the oil industry to (1) record sonic velocity data needed to generate synthetic seismic profiles, (2) acquire supporting data on rock properties,
and (3) generate logs to compare with data recorded using ISGS equipment;
• install piezometers at different elevations in each test hole;
• extract representative 4-inch-diameter core samples for comparative rock strength tests;
• conduct a pump test with standard equipment;
• sample water during drilling;
• record downhole features, structures, and possible water inflow with a videocamera.
The primary purpose of drilling the 8-inch test holes was to collect geophysical data for use in interpreting seismic reflection profiles. Sonic logs and other downhole geophysical information allow reflecting layers in seismic profiles to be correlated with specific rock units in the stratigraphic sequence. The seismic study now in progress is crucial to confirming the absence of major faults in the region, and to firmly establishing the continuity of the lithology and the thickness of the targeted bedrock units, the Galena and Platteville Groups. The uniform composition and continuity of the dolomite units is obvious from seismic data already acquired. When the final data are compiled and processed, the results will be published.
Geophysical data were also acquired on rock lithology, thickness, radioactive constituents, and porosity. Logs show that the Galena and Platteville Groups form a thick, homogenous unit that is low in porosity. Shale and clay are present only as thin partings. Spectral gamma ray logs show that levels of radioactive minerals in the bedrock are very low; they do not exceed 5 parts per million (ppm) for uranium, 6 ppm for thorium, and 6 percent concentration for potassium. Caliper logs indicated little change in the hole diameter of the Galena-Platteville interval, further confirming the generally stable and massive characteristics of the dolomites. Videocamera imaging also showed the units to be generally massive, with some shale partings and a few fractures. Some intervals were vuggy; others were featureless.
Geotechnical studies included the acquisition, description, and testing of 4-inch-diameter rock cores recovered from the Maquoketa, Galena, and Platteville Groups. Cores were examined for joints and other discontinuities, then tested to determine basic rock properties, such as specific gravity, unconfined compressive strength, point load indices, and Shore hardness. This information was supplemented by the data from geophysical logs to provide a complete description of the rock characteristics. Analyses indicate that the dolomite of the Galena-Platteville forms an excellent tunneling medium, but is not excessively hard rock (Shore hardness of 72 to 85) that would resist boring. Most fractures are healed (96 percent) and sound (96 percent). The dolomite cores had a Rock Quality Designation of 93.0 to 98.2 percent. Unconfined compressive strength ranged from 4,400 to 14,900 pounds per square inch (psi), and indirect tensile strength and point load indices were also high.
A pump test conducted in the upper Ancell Group (below the units where the SSC tunnel would be constructed) gave a transmissivity of 21,000 gallons per day per foot (gpd/ft), hydraulic 3 conductivity of 2.8 x 10" centimeters per second (cm/sec), and a storage coefficient of 0.0002.
Test results also showed little downward movement of water from the Platteville Group, implying a low vertical hydraulic conductivity of that unit. Piezometers installed at different elevations at each test hole often showed different water levels, further confirming the limited vertical movement of water in the Galena-Plattteville dolomites. These data, when viewed in conjunction with horizontal hydraulic conductivity data from previous drilling programs, demonstrate the very low overall permeability of the dolomite. Water samples collected during and after drilling were low in iron, sodium, and chloride content; levels of radioactive nuclides were also low, with uranium ranging from 0.146 to 2.86 ppb.
The results of the large-diameter drillhole program have added to the great quantity and diversity of data already available for the region, and support conclusions that the geologic conditions in northeastern Illinois are suitable for construction and operation of the SSC. INTRODUCTION
As part of the geological exploration of the proposed SSC site in Kane, Kendall and Du Page Counties (fig. 1), the Illinois State Geological Survey (ISGS) conducted extensive drilling (thirty 3-inch diameter test holes) and reflection and refraction seismic surveys. In addition, three large-diameter (8 inch) boreholes were drilled primarily to support the reflection seismic surveys and to provide the opportunity to collect other essential data. Geophysical logs acquired from these test holes were used to correlate data from seismic surveys to actual rock units. The results from these are summarized in this report. Earlier reports, such as "Siting the Superconducting Super Collider in Illinois" (DENR, 1985) presented the background for these studies. Also in 1985, the ISGS published the results of the first phase of its geological and geotechnical investigations.
Site suitability required both an environmental and a geological- geotechnical evaluation. The siting study consisted of four phases:
1. preliminary feasibility study (Kempton et al . , 1985; Hines, 1986); 2. investigation of a selected region *to locate the most suitable corridor for the SSC ring; 3. verification of predicted surface and subsurface conditions within the corridor and surrounding area by drilling test holes (Kempton et al., 1987a and b; Curry et al., 1988) and presenta- tion of the results in geological feasibility reports (Graese et al., 1988); 4. consultation services during the site selection process.
In this report we briefly summarize results of drilling large-diameter test holes, describe the procedures used to collect data, and interpret the samples and other data collected from the test holes. Descriptions for these test holes are on open file at the Illinois State Geological Survey. All laboratory test data will be on open file when analyses have been completed. Data from the previous test holes are presented in Kempton et al. (1987a and b) and Curry et al. (1988).
GEOLOGIC SETTING Every siting study begins with an investigation of the geologic setting of a proposed area. Surface and subsurface materials may restrict con- struction procedures and placement of surface and subsurface structures. Therefore, determining whether a project is geologically feasible or not depends on determining the site's stratigraphy--that is, the thickness, distribution, structure, lithology (composition), and other properties of all materials underlying a site. This is particularly important where structures are located underground.
In the proposed SSC study area in northeastern Illinois, unconsolidated, glacially deposited (Quaternary) materials overlie Paleozoic bedrock (fig. 1) that includes carbonates, shales, siltstones, and sandstones. The generalized stratigraphy of the region is shown on figure 2. Elevation R 5 E R 6 E R 8 E R 9 E
R 4 E R 5 E R 6 E R 7 E R 8 E R 9 E
ZZ2 SILURIAN (undiff.; dolomite)
. o miles |_ "TT^ kilometers ORDOVICIAN M o
|o ; s Maquoketa (dolomite & shale) 1
Platteville - ; Galena (dolomite) [ 1 W»A Ancell (sandstone) WM Prairie du Chien (sandstone and dolomite)
|. '. 'I CAMBRIAN (undiff.; sandstone and dolomite)
Figure 1 Geologic map of the bedrock surface.
of the land surface above mean sea level (m.s.l.) varies from less than 600 feet in the sou theast to more than 900 feet m.s.l. in the north- west. The glacial drift ranges from zero to more than 300 feet thick. In Kane County, the bedrock surface is dissected by valleys filled with glacial materials, The elevation of the floors of these bedrock valleys is one of the facto rs controlling the elevation of the SSC tunnel. The deepest bedrock val ley floor has an elevation of 450 feet above m.s.l. The tunnel containi ng the SSC must be constructed at least 50 feet below
(400-foot elevation ) the deepest valley to ensure tunnel roof stability and low groundwater inflow. FORMATION GRAPHIC LOG DESCRIPTION thickness (in feet)
HOLO- Grayslake Peal (0-15) •44- -4-1- -k|_ ++• Peat and muck CENE Richland Loess (0-5) Silt loam, massive
silt laminated DC Sand; and clay, Henry (0-70) < gravel, stratified Z Sand and cc Wedron (0-250) Till, sand and gravel, laminated sand, silt and clay LU ^?S^.'>Sv> Peddicord (0-35) Sand, silt and clay, laminated < Robein Silt (0-28) o ^ ^ tV» Organic-rich silty clay Glasford-Banner &>**<£;}.* Till, sand and gravel, laminated sand, silt and clay (0-375)
Dolomite, fine grained < Kankakee (0-50) cc lu rr Dolomite, fine grained, cherty _J -ID < Elwood (0-30) to Dolomite, fine grained, argillaceous; shale, dolomitic V Wilhelmi (0-20)
Shale, dolomitic; dolomite; fine to coarse grained, argillaceous
(0-210)
Dolomite, some limestone, fine to medium grained Wise Lake (120-150) B Dolomite, fine to medium grained, cherty < Dunleith-Guttenberg J2. (35-55) ± Dolomite, fine to medium grained with red brown shaly laminae > Quimbys Mill-Nachusa -'--'-r o Dolomite, fine to medium grained, slighty cherty Q (50) OC Grand Detour-Mitflin --/-,—/- o Dolomite, fine to medium grained, argillaceous (43) ^^7- Pecatonica Dolomite, fine to medium grained, cherty, sandy at base (38) Glenwood ' III ji'.J i VW'i Sandstone, poorly sorted; silty dolomite and green shale St. Peter Ss Sandstone, white, fine to medium grained, well sorted (60-520)
Q Shakopee Dolomite, fine grained z< Eminence (20-150) Dolomite, fine to medium grained, sandy, oolitic chert Potosi (90-225) Dolomite, fine grained, trace sand and glauconite Franconia (75-150) Sandstone, fine grained, glauconitic; green and red shale ' ' i » . > | ' . . y^<. z Ironton-Galesville < Sandstone, fine to medium grained, dolomitic DC (155-220) s03 < 7T7X Eau Claire (350-450) Sandstone, fine grained, glauconitic; siltstone, shale, and dolomite Mt. Simon (1400-2600) Sandstone, white, coarse grained, poorly sorted PRECAMBRIAN Granite, red !-/'< Figure 2 Stratigraphic column of bedrock and drift units in the study area north of the Sandwich Fault Zone in northeastern Illinois (modified from Kempton et al., 1985; not to scale). Bedrock units dip approximately 0.2 degrees to the southeast. Silurian dolomites, which occur at the bedrock surface in the east, are underlain by the Maquoketa, Galena, and Platteville Groups. The Galena is the surficial bedrock in areas near the western edge and the Maquoketa forms the surficial bedrock in the rest of the study area. Not present at the bedrock surface in the study area north of the Sandwich Fault, but encountered in the test holes, are the early Ordovician (Ancell and Prairie du Chien Groups) and late Cambrian (Eminence Formation) strata that underlie the Platteville Dolomite Group. Due to pre-Ancell erosion, the rocks of the Prairie du Chien Group and the Eminence Formation are absent from the northern and western parts of the study area. The geologic setting of the study area is thoroughly discussed in the SSC Preliminary Geological Feasibility Study (Kempton et al., 1985) and the Handbook of Illinois Stratigraphy (Willman et al., 1975). BEDROCK STRATIGRAPHY Because the injector tunnels and access shafts will penetrate the Silurian System, and the Maquoketa, Galena, and Platteville Groups (Ordovician System) (fig. 2) and because the tunnel would be located in the Galena-Platteville, these rocks are of primary interest for siting the SSC. The Ancell and Prairie du Chien sequences that directly under- lie these strata also were penetrated by the large-diameter test holes. Silurian System The Silurian formations in the study area consist primarily of light gray, fine-grained, thin- to medium-bedded dolomite with thin, green shaly partings. The Silurian has been completely eroded in some places and its thickness ranges from zero to more than 100 feet. Ordovician System The Ordovician System includes (from youngest to oldest) the Maquoketa, Galena, Platteville, Ancell, and Prairie du Chien Groups. Maquoketa Group consists of green, brown, and red shale with beds of fossil iferous carbonate rocks. It ranges from 130 to 210 feet thick where overlain by Silurian formations within the study area. Within the study area, the Maquoketa is 1 ithologically heterogeneous. The Galena and Platteville Groups are primarily gray to brown, fine- to medium-grained dolomite. The Galena Group is typically fine to medium grained, medium to thick bedded, and vuggy and vesicular. The underlying Platteville Group is fine grained, thinner bedded, and less vuggy and porous than the Galena Group. The Galena Group in the area is approximately 200 feet thick; the Platteville Group is 140 to 150 feet thick. The Galena Group is divided into three formations in the study area. The uppermost Wise Lake Dolomite is composed of relatively pure carbon- ates; the underlying Dunleith Dolomite is cherty and more vuggy. At the base of the Galena lies the Guttenberg Dolomite, characterized by red- dish brown shale partings. The Platteville Group, a blue-gray or brown, fine-grained dolomite, is divided into several formations that cannot be easily distinguished in subsurface samples; they will not be discussed here. The Ancell Group, primarily a white, fine- to medium-grained sandstone, is composed of two formations. The Glenwood Formation is not present everywhere and was not clearly differentiated in the samples, although it could be easily distinguished in some geophysical logs. Locally, the formation is a predominantly white, fine- to medium-grained sandstone that lacks the shaly facies prevalent in the formation elsewhere in northern Illinois. The St. Peter Sandstone is a white, fine- to medium- grained, well-sorted, well-rounded, friable to weakly cemented, pure, quartz sand. The only St. Peter Sandstone member differentiated in samples was the Kress Member. It is predominantly chert and oolitic chert, with thin beds of red and green shale; the Kress is apparently a residuum (Willman et al., 1975), and has a very irregular distribu- tion. Thickness of the Ancell Group in the study area varies from less than 200 feet to more than 400 feet (Buschbach, 1964). The Prairie du Chien Group is composed of a mixture of dolomite, sand- stone, and shale as much as 100 feet thick in southern Kane County; it is absent in the northern half of the area, where the St. Peter Sandstone rests directly on the Eminence Formation. The Shakopee Formation is a light gray to light brown, argillaceous to pure, yery fine-grained dolomite. The New Richmond Formation is composed of white, fine-to medium-grained, subrounded to rounded, friable, moderately sorted quartz sand. The Oneota Formation is composed of fine- to coarse-grained, light gray to brownish gray, cherty dolomite, and minor amounts of sand, shale, and oolitic chert; it is characterized by coarse grains. Cambrian System Only the Eminence Formation was encountered during drilling of these three test holes. The Eminence Formation is a light gray to brown or pink, fine- to medium-grained sandy dolomite with poorly sorted sandstone at the base. Willman et al. (1975) provides a more detailed description of these older units. GLACIAL DRIFT STRATIGRAPHY Drift samples collected from the three large-diameter holes were not studied. The glacial is stratigraphy of the area described extensively" in Kempton et al. (1985, 1987a and b), Curry et al. (1988), Curry and Kempton (1985), Kemmis (1978), Landon and Kempton (1971), Johnson et al (1985), Wickham, Johnson, and Glass (1988), and Berg et al. (1985). 1 - R 4 E R 5 E R 6 E R 7 E R 8 E R 9 E DE KALB KANE I COOK | | T T 42 42 N N I 1 J 90 4 30 DU PAGE 14 13 | tf T T 02 i 12 40 40 27A N 24 A N I /A 30 SSC-1^| SO i 1 T 1 29 A 26 I 39 ^ A 39 N N 0? f l 1 M23 SSC-2 [28 T T 38 38 11 ' N SSC-3 J|N N 22 A \ ^po I KENDALL ,16 vA20 WILL A21^4s A18 OS T T I 37 A19 37 N eO| N 1 R 4 E R 7 E R 8 E R 9 E O 1984 Test Hole A 1986 Test Hole 1985 Test Hole $ 8 in. Test Hole, 1986 Figure 3 Location of all SSC drilling sites. DRILLING PROGRAM The 8-inch diameter test holes allowed researchers to use the petroleum industry's standard borehole logging tools to conduct essential geophysical tests. The large-diameter holes also offered opportunities for hydrogeological and geotechnical testing not possible in the small diameter test holes. • Geophysical logging Geologists were able to run a complete suite of downhole geo- physical logs that indicated properties of the rocks in the test hole. Sonic logs run in each test hole provided data on seismic velocities needed to generate synthetic sei sinograms for the test region. Table 1. Location and approximate elevation for each test hole Land surface ISGS Test 7 1/2-minute elevation Township Location Eng. county hole map (±1 ft) & range section coord, numbers County Location SSC-1 Maple Park 841 T39N, R6E 3 4d 27257 Kane Kaneland School SSC-2 Napervil le 753 T39N, R8E 32 8f 27379 Du Page Fermilab SSC-3 Big Rock 688 T38N, R6E 23 2h 27329 Kane Wildon Road Test Holes SSC-1 and SSC-3 formed the endpoints of a seismic reflec- tion study conducted in western Kane County, and SSC-2 served as a control point for a north-south seismic survey line at Fermilab (fig. 3, table 1). The synthetic seismograms provided stratigraphic control for the seismic reflection lines; rock samples provided lithologic control. The Ancell Group is generally a rather featureless unit in seismic profiles; irregularities in the geological structure (folds, faults) are not readily apparent in this unit. Therefore, the test holes were drilled through the Ancell Group, giving the sonic probe access to deeper strata (Prairie du Chien, Eminence) and providing a basis for identifying reflections on seismic profiles. Other standard geophysical logs were run to provide detailed profiles of rock characteristics. ISGS personnel repeated many of these logs with Geological Survey equipment for the purpose of comparison with Schlumberger results. A spectral gamma ray probe allowed geologists to identify and measure specific radioactive elements as well as to validate the use of radioactive horizons for stratigraphic purposes. • Hydrogeological studies The size of the test holes allowed researchers to conduct new hydrogeological studies, particularly by permitting the installa- tion of triple piezometers to monitor water levels at three different stratigraphic intervals at the same site. Also, the piezometers themselves are large enough to permit limited sampling of water for quality analysis. Water samples collected during the drilling of SSC-1 were used to attempt to measure radon levels in the water; however, the samples were too disturbed to provide accurate measurements. A pump test was conducted using standard well pumping equipment at SSC-1 to determine the hydrogeologic properties of the Ancell Group and the degree of interconnection between the Platteville and Ancell Groups. Table 2. Thickness of units penetrated in test holes SSC-1 SSC-2 SSC-3 (ft) (ft) (ft) Drift 140 81 133 Silurian Fm. — 129 — Maquoketa Group 139 155 85 Galena Group 231 205 216 Platteville Group 111 116 109 Ancell Group Gl enwood 85 — 90 St. Peter 244 231 215 (Kress Member) 45 23 Prairie du Chien Group Shakopee — 80 — New Richmond — 35 — Oneota — 45+ 52+ Eminence Fm. 9+ * * — not present not penetrated Videocameras were lowered into all three holes to observe fractures, water inflow, and unsuspected visual characteristics. Brief descriptions of observed features are presented in the test hole section; complete descriptions are in Appendix B. a Geotechnical information Geologists collected 4-inch-diameter cores, each 20 feet long, from four stratigraphic intervals. These were collected because large- diameter core samples provide a more accurate representation of actual rock conditions and rock mass characteristics (tables 9 and 10, p. 27 and 28) than the 1.88-inch cores taken from the small- diameter test holes. Core samples were collected only from SSC-2 and sent to the Rock Mechanics laboratory at the ISGS for tests. Several important geotechnical characteristics were derived from the sonic logs run in each test hole. 9 Stratigraphic information Finally, the test holes provided further confirmation of our pre- viously acquired stratigraphic knowledge (and particularly added to data on sub-Ancell units). All three holes penetrated the Ancell Group, and SSC-2 penetrated most of the Prairie du Chien Group (table 2). Sample descriptions are found in Appendix A. GENERAL PROCEDURES Layne Western Company, Inc., received the drilling contract, which was awarded on the basis of competitive bidding. Finishing procedures, including piezometer emplacement and sealing of the holes, were bid separately: Rock and Soils Drilling Corporation completed SSC-1, and Layne Western Company finished SSC-2 and SSC-3. Researchers selected general locations for the test holes in areas that were suitable endpoints for the planned seismic work, and were located in or near the final study corridor. Selections were also based on convenience, location of utilities, and probability of obtaining permission to drill. These procedures were followed: " 9 The driller used both dual -wall, reverse circulation equipment (SSC-1) and standard single-wall, rotary drilling rigs. The drilling contractor provided an experienced driller and two to three helpers. 9 The hole was drilled to top of bedrock, drift samples collected, and surface casing set. • The hole was then drilled to total depth. The driller or an ISGS geologist took samples of bedrock at 5-foot intervals. • The hole was logged by staff from the Geological Survey and the Schlumberger Company. Layne-Western personnel lowered a video camera into the hole and recorded the strata, fractures, water inflow, and other features on videotape. • Three piezometers made from 1.5- or 2-inch-diameter (O.D.) plastic (PVC) pipes were assembled and lowered, one at a time, to the selected depths and stratigraphic intervals. Each pipe terminated at the lower end in a 10-foot screened section, which was encased in a gravel pack and then sealed with grout. • Surface casing was pulled and a short pipe with a locking cap was grouted in place to protect the PVC pipe. The site was restored to pre-drilling conditions. Sampling Procedures Geologists collected drilling chips and bedrock cores. Drilling Chips. Drift and bedrock samples were collected at 5-foot intervals during drilling. Drift samples were collected by strainer. Because of the unconsolidated nature of the drift, samples were of poor quality and were not studied. The geologist or a drilling assistant collected bedrock samples by strainer while drilling proceeded through shales or carbonates, and a bucket was used to collect sandstone samples. Samples were washed before storage. Test-Hole SSC-1 was drilled using dual-walled pipe and an air hammer with air circulation, and the rapid return of rock chips by air and the good condition of the bedrock samples provided an especially accurate record of the test hole. Because the dual wall, reverse circulation method was not used in drilling SSC-2 and SSC-3, chip samples were not as good as those from SSC-1. Samples from SSC-2 were particularly poor (ground up), possibly due to the type of drill bit used during drilling. Bedrock Core. Drilling technicians recovered four 4-inch-diameter, 20-foot-long bedrock cores in 10-foot sections from SSC-2. Two 20-foot cores were recovered from the Galena, and one each from the Maquoketa and Platteville. These cores were used for comparison with data from smaller diameter cores taken during earlier drilling programs. Core samples were tested in the Rock Mechanics Laboratory at the ISGS to determine various characteristics, including rock strength (Qu), specific gravity, and Shore hardness, as well as Rock Quality Designa- tion (RQD), frequency and dip orientation of fractures and joints, and several other rock properties. These and other factors are important in characterizing rock for tunneling suitability. Qu is a measure of unconfined compressive strength, and is expressed in pounds per square inch (psi). Shore hardness is obtained with a Schleroscope (hardness tester) manufactured by Shore Instrument and Manufacturing Company. Each value given is an average of the 10 highest of 20 readings. Rock Quality Designation (RQD) is one standard parameter for evaluating rock mass quality. This value (given as a percent) is the quotient of the sum of the length of all core segments greater than 8 inches long (between natural fractures) to the length of the core run. Disk fractures that develop as a result of shrinkage caused by loss of moisture or stress fractures from drilling or handling are not counted. Fracture frequency is determined by counting the number of natural fractures per 10 feet. As with RQD, this does not include drilling or handling-induced breaks along bedding. As would be expected, the correlation between RQD and fracture frequency is generally good. Distance between horizontal separations is the length of core segments removed from the core barrel. This measurement is affected by the mechanically and handling-induced separations along bedding as well as natural fractures. If the distance between horizontal separations is less than 0.2 foot, the accompanying RQD and fracture frequency may not reflect severely broken core because the separations occur along bedding planes during or after drilling. Geophysical Logging In order to record various rock properties, the ISGS field team and Schlumberger Well Logging Company conducted geophysical tests at all three test holes. Geophysical logs that the ISGS ran sequentially in the test holes included temperature-conductivity, caliper, spontaneous potential, single-point resistivity, density, and natural gamma ray-neutron. The equipment was a Log-Master 554-E carryall -mounted borehole logger. 10 (ft) Depth Depth (ft) 0. Resistivity Resistivity (deep induction) Gamma Gamma Spontaneous potential Neutron porosity Spontaneous potential Neutron porosity (compensated neutron) (compensated neutron) Figure 4 Comparison of selected geophysical logs from Test Hole SSC-1: Schlumberger (left) and ISGS (right). Logs run by Schlumberger included gamma ray, spectral gamma ray, long- spaced sonic (LSS), compensated neutron, lithodensity, dual (deep and medium) induction, and spontaneous potential (SP). Brief explanations of some of the geophysical logs used by both the ISGS and Schlumberger are included in Appendix C. Most of the logs were run at all test holes; selected logs are illustrated in figures 11, 13, and 15, which appear later in this report. In figure 4, the resistivity, spontaneous potential, compensated neutron, and gamma ray logs recorded in SSC-1 by 11 Table 3. Characteristics of piezometers installed in each test hole Elevation of Outer Hole and Depth from bottom of diameter piezometer ground screened (O.D.) of Stratigraphic units; no. surface (ft) section (ft) piezometers lithology SSC-1-1 421 420 1.5 Galena Group; dolomite SSC-1-2 521 320 1.5 Platteville Group; dolomite SSC-1-3 640 201 1.5 Ancell Group; sandstone SSC-2-1 317 436 1.5 base of Maquoketa Group; shale SSC-2-2 417 336 2.0 Galena Group; dolomite SSC-2-3 517 236 1.5 top of Platteville Group; dolomite SSC-3-1 277 411 1.5 upper Galena Group; dolomite SSC-3-2 377 311 2.0 lower Galena Group; dolomite SSC-3-3 477 211 1.5 top of Platteville Group; dolomite Note: length of screen is 10 feet. the ISGS are compared with the corresponding logs recorded by Schlumberger. Although the logs are not presented at the same scale, responses shown on the ISGS logs are similar to those on the Schlumberger logs. This corroborates the log response of previous ISGS geophysical logging conducted during the SSC exploratory drilling programs (Kempton et al., 1987a and b; Curry et al., 1988). Videocamera Imaging Each hole was videotaped after drilling ended but before the piezometers were installed. This procedure was delayed at least 12 hours to allow material to settle out of the water column. The contractor then lowered the camera to the bottom of the hole at a constant rate while the operator described the image. The depth of the camera was continuously displayed on the monitor and also recorded on tape. The videotapes are on file at the ISGS, and a written log is given in Appendix B. Features detected by the videocamera included size and degree of vuggi- ness; continuity, size and number of fractures; and thickness and number of shale partings. The images also showed water inflow (from the casing seat, and from bedrock joints), and other features such as pyrite deposits, and color and texture changes that would be used to correlate stratigraphic information from samples and logging. Breakout features, particularly in shale beds, were also evident. 12 Groundwater Data Piezometers. Three piezometers were installed in each hole, one at the proposed tunnel elevation (320 feet m.s.l.) and one each at elevations 100 feet above and below it. All piezometers were standing-water-level head types, constructed of 1.5-inch or 2-inch-diameter PVC pipe, with a 10-foot-long section of screen at the bottom. All piezometers installed in SSC-1 were 1.5-inch in diameter. A 2-inch-diameter piezometer was installed at the proposed tunnel elevation in SSC-2 and SSC-3, enabling researchers to use a 1.8-inch-diameter pump to collect water samples. Piezometers in SSC-2 and SSC-3 monitor different stratigraphic levels but approximately the same elevations as SSC-1 (table 3). The installation consisted of placing and sealing the piezometer in permeable backfill material (pea gravel) opposite the zone to be tested. Above and below the test section, cement grout sealed the space between the borehole walls and the pipe. After the deepest piezometer was installed, a plastic guide was slipped onto it. This guide, along with others added to the second (and third) piezometers, prevented the piezometer assembly from tangling. A short section of surface casing was cemented in place to protect the tops of the piezometers. Bentonite was used as a seal between open intervals at SSC-1, but construction was otherwise similar to SSC-2 and SSC-3. Figure 5 illustrates the general configuration of all three holes. The water level in a pipe is measured using an electric drop line. Water Samples. Water samples were collected during the drilling of Test Hole SSC-1. The quick return of samples by air allowed the sampling of groundwater from precise stratigraphic intervals. Geologists took water samples from four stratigraphic horizons, processed them in a mobile laboratory at the site, and transferred them to the Geological Survey for analysis of radioactive content (uranium-234 and -238). Researchers from the Illinois State Water Survey (ISWS) will collect water samples from the piezometers installed at each test hole. Samples will be analyzed to monitor water quality. Pump Test. ISWS staff conducted a pump test at Test Hole SSC-1 and used the data to calculate the transmissivity and hydraulic conductivity of the St. Peter and Glenwood Sandstones. The close proximity of the Kaneville Vocational Center water well to SSC-1 (900 ft) offered re- searchers a unique opportunity to use the water well as an observation well for the pump test. The data were used to determine the storage coefficient. After drilling, reaming, geophysical logging, and partial backfilling of the test hole were completed, the drilling contractor set a packer at the top of the Glenwood Formation and a pump was inserted through the packer into the top third of this formation. Air lines with altitude gages were set to allow measurement of water levels both above and below 13 PVC pipe Protective casing Sandstone'- '." Figure 5 Generalized diagram of triple piezometer installation. the packer. In the test well, the pump worked at a rate of 222 gallons per minute (gpm) for 436 minutes, while an observer periodically recorded water levels at both the test and the observation wells. Water levels were then observed for 60 minutes during the recovery period. A water sample collected near the end of the pumping period was subjected to a complete mineral analysis (Visocky and Schulmeister, 1988). 14 RESULTS Geology Previous interpretations of general bedrock stratigraphy were confirmed by data collected during drilling of the three large-diameter holes. The holes provided detailed records of bedrock lithology, particularly of the bedrock units targeted for the proposed SSC tunnel: the Maquoketa Shale Group with its variable lithology, and the Galena- Platteville Groups, which are more uniform in composition and texture. Although data on the underlying Ancell Group are not directly relevant to siting the SSC, the hydrologic data relate to an important aquifer directly below the Galena-Platteville. Few sampled wells in the study area had penetrated the full thickness of the Ancell, and complete suites of geophysical logs in particular were lacking. The results presented here were developed from observations on geology from downhole geophysical logs, samples, cores, and videocamera imaging. Maquoketa Shale Group. Video images of all three test holes showed the Maquoketa shale to be generally massive with no evidence of major fractures. No signs of major water inflow or material breakout were evident. Samples confirmed the general formation descriptions (fig. 2). Shale percentage increased toward the base, although samples from the lower 30 to 40 feet were visually indistinguishable from each other. Geophysical logs indicated a steady downhole increase in natural radioactivity in the Maquoketa, corresponding to the increase in the percentage of shale, reaching a maxi mum at the base of the Maquoketa and showing a sharp decrease upon enteri ng the Galena. Just above that horizon, thorium reached concentrati ons of 9 ppm, and uranium 3 ppm. Geophysical logs indicate low porosi ty similar to that of the Galena- Platteville. Areas of higher porosi ty occurred in the upper Maquoketa, specifically in dolomite sequences. Tests run on 4-inch core from near the top of the Scales Shale (lower Maquoketa) in Test hole SSC-2 show an average unconfined strength (Qu) of 5,984 psi and an average Shore hardness of 53. Galena and Platteville Groups. The videocamera images of shale partings, vugginess, massiveness, and the overall appearance of the Galena and Platteville Groups closely corresponded to the data from the extensive coring program conducted during 1984-86. The Galena appeared vuggy in some intervals. Most of the fractures were small and discontinuous. The Platteville was similar to the Galena but less vuggy. In both groups, the borehole was generally smooth, showing no signs of large breakouts. Caliper logs also showed few irregularities in borehole diameter, indicating that the dolomite was hard and stable. Shale partings were common, varying from less than one per foot to many per foot. Two or three narrow breakouts were evident in the Galena in Test Holes SSC-1 and SSC-3, probably reflecting the presence of slightly thicker beds of clay (up to 1.0 inch thick). Overall, the video recordings show the Galena and Platteville sequences to be hard, stable, relatively massive dolomite with few fractures. 15 100 300 500 700 900 Depth in feet Figure 6 Concentrations of uranium (ppm) measured in geologic materials in SSC-1. The plot compares instrumental neutron activation analyses performed on rock chips in the laboratory with downhole measurements made with a spectral gamma ray sonde. (From Gilkeson et al., 1988.) Field descriptions of sample chips conformed closely to core descrip- tions of test holes from earlier drilling programs. The boundary between the Galena and Platteville Groups is somewhat indistinct in all three test holes, although it was obvious in earlier core studies. An abrupt increase in the number of shaly beds or partings (induction log) was noticeable in the Guttenburg Dolomite at the top of the Platteville. In general, geophysical logs indicated low porosity with some varia- tions, particularly in the Galena. The fine-grained Platteville generally exhibited lower porosity than the Galena (most evident in SSC-2). Natural radioactivity in the Galena-Platteville is lower than in the Maquoketa, with uranium concentrations of approximately 0.5 to 1.0 ppm (fig. 6), presumably in shale or clay beds. Tests of rock cores from SSC-2 compared favorably with tests on smaller diameter cores from previous drilling programs, and further confirm the overall suitability of the Galena-Platteville for tunneling. Rock strength tests were made on three 4-inch cores, each from 20-foot intervals—two in the Galena and one in the Platteville. Average values ranged from 8,000 to more than 10,000 psi; Shore hardness ranged from 72 to 85. Fracture and joint faces in the dolomite groups were generally sound (unaltered) and wavy, indicating a high shear strength. RQD values, a good indicator of rock mass quality, were consistently high, and generally ranged from 95 to 100 per cent. 16 Results from the pump test of SSC-1 indicate that there is no short-term interaction between water in the Platteville and water in the Ancell. Few fractures and joints connect these units, so water levels in the Galena-Platteville do not respond quickly to changes in water levels in the Ancell. The relatively impermeable Galena-Platteville sequence not only confines the Ancell, but retards the downward flow of water (Dixon et al., 1988; Graese et al., 1988). Ancell Group. Video images of the Ancell Group appeared generally featureless, except for thin (1 to 2 feet) cemented zones at the base of the Glenwood Formation and near the base of the St. Peter Sandstone. These zones are cemented by pyrite and other mineral overgrowths. Vertical fractures, evident in SSC-1 through much of the Ancell, may have been caused by the high, horizontal in situ stress in the area. The Kress Member in Test Hole SSC-1 (fig. 14) showed a variable texture due to many changes in lithology, which included chert, shale, dolomite, and sandstone. In all three test holes, the diameter of the borehole increased in the Kress interval because the soft shales collapsed. Test Hole SSC-2 was blocked by the breakout of shale beds in the Kress. Geophysical logs in Test Holes SSC-1 and SSC-3 indicated distinct changes in natural radioactivity, porosity, and conductivity at approx- imately 80 feet below the Platteville-Ancell contact. The phenomena were particularly evident in SSC-1, where pyrite-cemented samples correlated with the changes in the geophysical logs. Also in SSC-1, gamma ray intensity steadily increased from the base of the Platteville to the same interval, where it abruptly dropped from the maximum value of 4 ppm uranium to a \/ery low 0.5 ppm uranium (fig. 6). A gamma ray inflection also appeared at approximately the same interval in SSC-3. This stratigraphic horizon may be equivalent to the Daysville Dolomite Member, the basal member of the Glenwood Formation in the area. Samples exhibited little variation throughout the Ancell. However, in two of the test holes, the cemented zones probably represent the base of the Glenwood; this is supported by geophysical data. The Glenwood in SSC-1 and SSC-3 is at or greater than its maximum reported thickness of 75 feet (Willman and Buschbach, 1975). It is not present in SSC-2. The descriptions of the St. Peter Sandstone samples and data from geo- physical logs conform to descriptions from test holes and wells drilled previously into the formation. Gamma, induction, and in one instance, porosity logs produced a similar response at approximately the same stratigraphic interval in each test hole. In SSC-1, samples of pyrite- cemented sandstone were collected from this interval, which was probably thickest in this test hole (5 feet). This horizon was apparently continuous across the study area and might be useful as a stratigraphic marker. It is characterized by a particularly large and abrupt increase in natural gamma radioactivity; the uranium concentration rose from less than 1 ppm to 5 ppm, and thorium to 6 ppm (fig. 6). The basal Kress Member varied in thickness from 44 feet in SSC-1 to less than 5 feet in SSC-3. Lithology varied from predominantly chert with red and green shale (SSC-1) to predominantly blue-green shale (SSC-2 and SSC-3). The shale in the Kress is relatively soft and subject to 17 breakout. A zone of high gamma radioactivity (16 ppm thorium), apparently associated with basal shale in the Kress, occurred in SSC-1. Prairie du Chien Group and Eminence Formation. The Prairie du Chi en Group, which underlies the Ancell, has been eroded and thins northward. Although it is absent in Test Hole SSC-1, where the Kress lies directly on the Eminence Formation, the section appears complete in SSC-2 and truncated in SSC-3. A Shakopee thickness of 105 feet and a New Richmond thickness of 35 feet were encountered in SSC-2. However, no geophysical or video data are available for this sequence in SSC-2 because of hole collapse. The Oneota was encountered in SSC-2 and SSC-3. In SSC-3, it was interlayered pink, gray or brown fine- to medium-grained dolomite. Gamma ray readings and porosity were low. Shaly zones were more evident than in the Galena-Pi atteville. Hydrogeology In informal nomenclature, the Maquoketa and the Galena-Plattevil le form a confining bed between the midwest sandstone aquifers (Ancell Group and Ironton-Galesvil le sandstone; fig. 2) and the upper bedrock aquifer (predominantly fractured Silurian and Maquoketa dolomites). Formal hydrostratigraphic units are discussed in Visocky, Sherrill , and Cartwright (1985). The low permeability measured in these units (Kempton et al., 1987a and b; Curry et al., 1988) implies slow water movement through them; and this was directly confirmed by the pump test conducted at SSC-1. Interaction between water in the Ancell and the PI atteville is long term, with extremely slow recharge to the Ancell through overlying strata (Graese et al., 1988; Dixon et al., 1988). During the pumping test, the observed drawdown in the St. Peter was about 49 feet after 436 minutes; Platteville water levels in the upper air line had only fallen about one foot. The final drawdown at the observation well was 2.83 feet. An analysis of the data from this well resulted in the following values: transmissivity was 21,000 gpd/ft; hydraulic conductivity, 58 gpd/sq ft (2.8 x lO'^cm/sec); and storage coefficient, 0.0002. The storage coefficient was in the artesian range, indicating that some contribution was coming out of storage from the Platteville during the early portion of the test. After about 100 minutes, the data points fell on the nonleaky artesian (Theis) curve, implying no downward movement of water from above; however, the test may not have been long enough to register a minor downward leakage. The movement of water out of storage was suspected because of the fracturing observed above the Ancell by the videocamera. Complete test data and further discussion are presented in Visocky and Schulmeister (1988). Every month since February 1987, field technicians have recorded water levels on the test holes using an electric drop line. Water levels stabilized almost immediately in the piezometers in all three holes-- with the exception of SSC-2-1 and 2-2. Few changes other than minor fluctuations have occurred since measurements began (table 4). SSC-2-1, after initial minor fluctuations, has dropped steadily, and may be 18 li tli I CM CO CO CM cn >1 CO CO O cn cn CD LO CM CD VD CO CO LO u o o **- co CD >> • • • • CM CM t_ co CM CD en Q LO CM LO LO CM CD O CM Q. o CO en LO CM CO CO CO CO CO en CD CM CO CO CO 1— <3- o cn LO CM o CO cn LO CM ^1- «3- O CO 00 CD CTi f— CM ^1- ro CD CO o CD LO f— CM cn cn cn CD CD O en cn r-. i— LO LO CM CM -=)- «a- C0 CD t— LO 00 o LO CO CD ^f cn o i— 4-> • !-» CO CD cn ro t—i LO CM CO "3" «d- CL o o o o O O CD O O QJ o o o CD O o CD o O -o CD- OCD o o o o CD O CD o CD o o O O CD co CO 00 CO LO CO 00 CO co CD CD CD o o o CO CO CO CO CO CO CO CO CO CO CO .c Q- (O • C_ r— «3- cn ro > •i- > cu _* ro ro QJ +J t- O c c r— ro CD 3 QJ CO .O 1- -l-> cr I— r— ID »-> c 19 SSC-1 SSC-2 SSC-3 depth feet 1 2 3 1 2 3 1 2 3 V V V UBA 1X UBA 100- UBA 1V V V 200- V 1,2,3 ANCELL V V V V 300- ANCELL V water level in piezometer 400- i __^_, regional level-upper V UBA bedrock aquifer _V_ regional level-midwest 500- sanc^ stone aquifer ANCELL ANCELL 600 -" Figure 7 Comparison of piezometer levels with regional water levels. responding to seasonal variations. SSC-2-2 may have been slow to stabilize; the initial high water level reading was probably not due to equipment problems. Water levels at SSC-1 are identical in all three piezometers. Since the pump test conducted at SSC -1 registered little interaction between the relatively impermeable Pla tteville Group and the Ancell Group, the seals between piezometers might have failed, or fractures (visible in video- tapes) might have allowed passage of water between units. Water levels in the three piezometers a ssumed nearly equal elevation, although the pump test implied little v ertical interconnection of joints. Locally, water levels in the Galena -Platteville are approximately at 650 feet elevation (200 feet depth) . The water levels in all SSC-1 piezometers appear to reflect the Ance 11 potentiometric surface, not the Galena- Platteville. Water levels in SSC-2 differed greatly, reflecting the expected distri- bution of levels in the Maquoketa and the Galena-Platteville, since lower stratigraphic intervals generally exhibit lower water levels. The wide variance in water levels in different stratigraphic horizons of the Galena-Platteville is further evidence of the low vertical hydraulic 20 conductivity of the dolomite, since a high vertical hydraulic conductiv- ity would allow water levels to equalize quickly. This is best seen in SSC-2, where in response to regional lowering of the piezometric surface of the deep sandstones (Ancell, Ironton-Galesville, Visocky et al., 1985), water levels in the Galena-Plattevil le have also dropped. Because of the dolomite's low vertical hydraulic conductivity, however, water levels in the Maquoketa and the Galena-Platteville have responded much more slowly than have water levels in the sandstones. Water levels in the upper Galena also are higher than those in the lower Galena, and levels measured in the Maquoketa stand more than 300 feet above these. At first, piezometers SSC-3-2 and -3 exhibited nearly identical levels, while the level in SSC 3-1 was 10 to 12 feet higher. This difference in water levels has now increased to more than 30 feet, and probably reflects the effect of seasonal changes on the shallower piezometer. In figure 7, approximate water levels in regional aquifers are compared with water levels measured in the nine piezometers. The upper bedrock aquifer is heavily utilized for domestic, industrial, and muncipal supplies, mainly east of the Fox River. The midwest sandstone aquifers primarily supply industries and communities throughout the proposed site. To the east (SSC-2), the difference between piezometer levels and the water level in the midwest sandstone aquifers is evident: the potentiometric surface of the aquifer has been lowered by overpumping, and water levels in the Galena-Platteville have been slow to adjust due to low permeability. To the northwest (SSC-1), water levels in the midwest sandstone aquifers have fallen only slightly; levels in the piezometers and both regional aquifers are similar. All of the water levels are within the range expected for the Galena-Platteville in the area. Some vertical interconnection is implied by the similarity of measurements in SSC-3-2 and SSC-3-3. Water Temperature. Water temperatures were recorded by Geological Survey staff following completion of drilling, although schedules precluded waiting for temperature equilibrium to be established. Temperatures ranged from 50.0 to 54.0° F (table 5). Table 5. Water temperatures recorded after drilling Interval Temperature Temperature measured range gradient Comments (ft) (°F) (°F/100 ft) SSC-1 296.0-989.9 51.5-50.0 0.22°/100 run immediately after drilling SSC-2 69-903 50.5-51.5 0.12°/100 8 days after drilling SSC-3 169.0-909.4 51.0-54.0 .41°/100 run immediately after drilling Note: SSC-l--anomaly at 814-819 feet--a 0.5° F temperature change. 21 Groundwater Quality. The Water Survey analyzed water samples recovered from the Ancell in SSC-1. Results indicated that the Ancell is a bicarbonate water of overall good quality. It has a total dissolved mineral concentration of 311, and low iron, sodium, and chloride contents (Visocky and Schulmeister, 1988). Radioactive Nuclides from Groundwater. Analysis of the four water samples taken from SSC-1 showed an increase in levels of radioactive nuclides with greater depths. Uranium-238 measurements were 0.146 to 0.859 parts per billion (ppb) in the Galena-Plattevil le; the single Ancell measurement was 2.86 ppb. Percentage of radon was not measured due to the sampling technique used. Further information on the presence of radioactive nuclides in the upper bedrock groundwater may be found in Gilkeson et al. (1988). Spectral Gamma Ray Logs The spectral gamma ray log measures separately the concentration of radioactive potassium, uranium, and thorium. In the study area, levels of these elements are very low, not exceeding 5 ppm for uranium, 6 ppm for thorium, and 6 percent concentration for total potassium (figs. 6, 8, and 9). Correlations of these three elements between Test Holes SSC-1, -2 and -3 are shown in figure 10. The highest levels of potassium and thorium are found in all three holes at the base of the Maquoketa (particularly just above the Maquoketa-Galena contact). Uranium is present in higher than average levels in the same interval at SSC-2 and -3. Higher than average concentrations of all these elements are found at the base of the Glenwood and near the base of the St. Peter. For a detailed description of results of the spectral gamma ray logs, see Gilkeson et al. (1988). Caliper Logs Irregularities in borehole diameter often indicate relative differences in rock strength, breakouts, and fractures, although they may result from changes in the drill bit or other variations in drilling technique. Caliper logging detected few irregularities, other than thin shale partings, within the Galena-Plattevil le. Only in Test Hole SSC-2 did a significant interval in the Galena show a minor increase of 0.1 inch in hole diameter. This interval, between 552 and 585 feet deep, is well below the tunnel depth of 433 at that point. Large changes in diameter occurred only in shale breakouts in the Kress Member. 22 500 Depth in feet Figure 8 Concentrations of total potassium (%) measured in geologic materials in SSC-1. The plot compares instrumental neutron activation analyses performed in the laboratory with downhole measurements made with a spectral gamma ray sonde. (From Gilkeson et al., 1988.) 100 300 500 700 900 Depth in feet Figure 9 Concentrations of thorium (ppm) measured in geologic materials in SSC-1. The plot compares instrumental neutron activation analyses performed on rock chips in the laboratory with downhole measurements made with a spectral gamma ray sonde. (From Gilkeson et al., 1988.) 23 SSC-2 SSC-1 30 K .1 Total jo Radiation IE" Uranium(ppm) Potassium!(%) |3 Gamma iS" I'D (API) 13 Figure 10 Stratigraphic correlations of spectral gamma ray records showing concentrations of total potassium (%), equivalent thorium (ppm), and equivalent uranium (ppm) for in situ measurements in three test holes in the SSC study area. Location of the test holes is shown in figure 3. (From Gilkeson et al., 1988.) 24 Table 6. Laboratory logging of Rock Quality Designation (RQD) and fracture frequency of SSC-2 compared with values from adjacent Test Holes ISGS F-l, S-28, S-29 SSC-2 F-l S-28 S-29 Averaige RQD (X) per formation Maquoketa 100.0 97.3 99.2 98.8 Wise Lake 96.7 99.6 100.0 98.3 Dunleith 93.0 99.0 100.0 95.0 Platteville 98.2 --- 99.9 100.0 Average fracture frequency (frac/ft) per formation Maquoketa 0.00 0.24 0.06 0.11 Wise Lake 0.50 0.21 0.03 0.59 Dunleith 0.82 0.05 0.88 Platteville 0.1 - — 0.38 0.09 Geotechnical Characteristics Rock Strength. Core samples were taken only from Test Hole SSC-2; approximately 20 feet of core each was taken from the Maquoketa shale (310 to 331.8 feet), and the Wise Lake (410 to 427.7 feet), Dunleith (480 to 499.6 feet), and Platteville (580 to 599.4 feet) dolomites. Laboratory logging yielded data to compare with RQD and fracture frequency data for adjacent boreholes from previous drilling programs (table 6). All cored sections of SSC-2 yielded 100 percent recovery. Fractures were found only in the dolomite units; they are characterized as fol- lows: 26 percent with some degree of filling, 26 percent of the filled joints were mineralized, and 96 percent were healed. Ninety-six percent of all the joints were sound, 15 percent planar, 82 percent wavy, and 3 percent uneven. Asperities (irregularities on joint faces) are characterized as 11 percent rough and 89 percent smooth, and one fracture displayed slickensides (table 7). Ninety-three percent of all fractures dip from 70 to 90 degrees. Number and dip orientations of joints for three 20-foot core samples from SSC-2 are shown in figure 11. There was considerable range in degree of vugginess (porosity) and number of discontinuities in samples selected for unconfined compressive strength (Qu) tests. These differences in the condition of the samples produced the range of values for Qu presented in table 8. Typically, rock strengths measured on 4-inch cores yield values 21 to 25 percent lower than the values for 1.88-inch cores of the same material (Johns, 1966; Pratt et al., 1972). The strength reduction found for the Wise Lake Dolomite and Platteville Group are on the order of 15 to 20 percent. The other tested samples show stronger values for the larger core. The large-diameter cores form a small sample set in comparison to the testing performed on the 1.88 inch-diameter cores (table 9). 25 Table 7. Discontinuity characterization for 4-inch core from Test Hole SSC-2 Maquoketa Wise Lake Dunleith Platteville Fi 1 1 ing none 5 14 1 partial 4 1 complete 2 Type mineral ized 4 2 1 healed 9 15 2 Condition sound 9 15 2 altered 1 Roughness planar 1 3 wavy 8 13 1 uneven 1 Asperities rough 2 1 smooth 9 14 1 slickensided 1 Total joints 9 16 2 filled 4 2 1 condition 9 16 2 roughness 9 16 2 asperities 9 16 2 Sonic Velocities. Sonic velocities were determined for each stratigraphic interval from the long space sonic (LSS) probe that was lowered into each hole. Average rock mass values for compressive wave velocity, Poisson's ratio, shear modulus, and bulk density were determined from the log and are displayed in table 10. A low water level in Test Hole SSC-1 precluded measuring properties of the Maquoketa in that hole. (LSS probes must be immersed in fluid.) Velocity values in the Galena Group (Wise Lake and Dunleith) and the Ancell Group in SSC-1 are 10 percent less than values obtained from the same strata in SSC-2 and SSC-3. This may be due to the location of joints in proximity to SSC-1. In general, the data support results from previous test holes (F-l to F-17, S-18 to S-30) and confirm the strong, homogeneous nature of the bedrock in the site area. In situ sonic velocities measured by the LSS probe were used to calculate values for wave velocity, Poisson's ratio, shear modulus, and bulk density. Values from each test hole for each formation or group are listed in table 10. A comparison of the average compressive wave velocities from the field to the values derived from bedrock core in the laboratory (table 11) shows a s/ery high ratio, which is another indication that the rock mass quality of the site is good to excellent. 26 — —1-. i I — i I X o >> co ,-h r-» CO E c -a qj t- CO l~~ CM CD col CD co co CD ld «d- en o «d- CM r-» Oi CO •r- O O C Q. CM CM CM CO CO ro «3- 1—1 ro Q CL.— -i- ^—" CO CO o cd en CO CM 01 CM en ^j- co r-- oo r-- r-^ r- co o •r- >, M- +-> CO O r-H r-t co co en «* CO en CD NCOIV CO CO CO en i^ CO CJ > a> fa CM CM CM CM CM CM CL t- CO Ol ai t_ 4-> rj c CD CO i-H O CO CD O CO i-H CM i-> ai-— Ln cm o cm en CM <—l CD cm ai co +j &« c: « CM o o QJ +-> CD E <0 -o <0 CT3 (U i- o co CO co CO en •i— -i— (O TT CO «3- i— 1 CD CO ai X O O C CL CO co r^- 00 o ai CC CL.— •r---' i-H +-> .c cj ai +j .— CD CO Q. co O O 3 r- co co ioo>t i—i ai o oo ai i— X i— co CO CO CO co ai CO 1— 3 "O -i- O CO s: a. co co co CO .—< en CO «* i-H CO «3" oo o >=i- cor-irv 1— co en co f- co oo co o co en CO CD QJ CD QJ QJ QJ QJ CO 03 +-> 4-> +-> CJ Q. O >, CO CO E E E E or +-> I I c O O O C o o o o c i— i— (O i—i—i— (O i—i— re i— ,— ai QJ ci_ CO cm ai a. E -c CO CO co co en CO 1^. 27 Table 9. Comparison of unconfined compressive strength for 4-inch and 1.8 inch cores Strength 4-inch core 1.8-inch core reduction Unit (psi) (psi) (%) Maquoketa Shale 5,948 4,405 none Galena Wise Lake 8,018 10,034 20.0 Dunleith 8,593 7,600 none Platteville 10,255 12,169 15.7 Table 10. Mean values for rock mass characteristics calculated from in situ sonic velocities Compressive Shear wave wave Shear Bulk velocity velocity P oisson 's modulus density 6 x (ft/sec) (ft/sec) ratio (psi 10 ) (g/cc) Borehol e SSC-1, Kaneland Galena Wise Lake 16,048 8,811 0.273 2.75 2.63 Dunleith 15,741 8,832 0.267 2.76 2.62 Platteville 17,000 9,411 0.277 3.22 2.69 Ancell 10,804 6,245 0.245 1.21 2.29 Borehol e SSC-2, Fermi lab Silurian 15,787 8,711 0.279 2.74 2.68 Maquoketa Shale 9,098 5,542 0.195 1.04 2.52 Dolomite 12,276 6,896 0.268 1.65 2.58 Galena Wise Lake 18,124 10,065 0.276 3.68 2.69 Dunleith 16,920 9,496 0.268 3.21 2.63 Platteville 17,688 9,789 0.278 3.46 2.69 Ancell 12,176 6,929 0.258 1.54 2.37 Borehol e SSC-3, Big Rock Maquoketa Shale 8,681 5,368 0.188 0.97 2.51 Dolomite 11,398 7,110 0.180 1.78 2.61 Galena Wise Lake 17,751 9,801 0.279 3.50 2.67 Dunleith 17,374 9,686 0.273 3.37 2.66 Platteville 17,150 9,543 0.275 3.29 2.68 Ancell 11,272 6,615 0.235 1.37 2.32 28 Table 11. Comparison of field and laboratory compressive sonic velocities Field Laboratory Unit ; ft/sec) (ft/sec) Ratio Silurian 15,787 18,583 0.85 Maquoketa Shale 8,916 13,091 0.68 Dolomite 12,245 16,782 0.73 Galena Wise Lake 17,535 20,046 0.87 Dunleith 16,654 19,015 0.88 Platteville 17,284 19,772 0.87 15 Joints 15 Joints Figure 11 Dip of fractures and joints in the (a) Wise Lake Formation (Galena Group) at 410.0 to 428.0 feet; (b) Dunleith Formation (Galena Group) at 480.0 to 499.6 feet; and (c) Platteville Group at 580.0 to 599.4 feet. 29 30 TEST HOLE SSC-1 Location: NW1/4, NW1/4, SE1/4, Sec. 3, T39N, R6E, Kane County Property: Kaneland Vocational Center Surface Elevation: 841 feet Total Depth: 994 feet Stratigraphy The stratigraphic column in figure 12 shows the lithologies and thicknesses of the rock units encountered in Test Hole SSC-1. The hole penetrated to the top of the Eminence Formation (upper Cambrian). Encountered were (top to bottom) 140 feet of glacial drift; 139 feet of interbedded greenish gray and olive-gray shale and dolomite (Maquoketa Shale Group); 231 feet of medium-grained, yellowish brown dolomite (Galena Group); 111 feet of fine-grained, brown and bluish gray dolomite (Platteville Group); 374 feet of fine- to medium-grained, rounded, pure quartz sand (Ancell Group: Glenwood and St. Peter Sandstones), including 45 feet of white to gray oolitic chert, fine- to medium- grained sand, pink dolomite, and reddish brown and gray-green shale (Kress Member, St. Peter Sandstone); and 9 feet of light pink to tan, sandy dolomite (Eminence Formation). Geophysical Logging Geophysical logs run by the ISGS in Test Hole SSC-1 included caliper, spontaneous potential, single-point resistivity, natural gamma radiation, neutron, and density. Dual induction, gamma ray , lithoden- sity, long space sonic, and natural gamma ray spectroscopy were logged by Schlumberger. Figure 13 shows the gamma ray, dual induction (SP and long induction), and density porosity logs recorded at SSC-1 by Schlumberger. The increasing radioisotope contents of the Maquoketa Group and the Glenwood Sandstone are evident in the gamma ray log (fig. 13). The abrupt decrease in radioisotopes at 684 feet corresponds with a lithological change to dolomite, and a pyrite cemented zone marks the base of the Glenwood. The abrupt change of porosity at the Platteville/Glenwood contact is evident on the density porosity log at 611 feet. The Galena appears to contain more shale partings at Test Hole SSC-1 than at SSC-2 or -3, but the inflection at 350 to 375 feet appears to correlate with a similar inflection in the deep induction log on the SSC-2 log (fig. 15). These may represent a volcanic clay deposit (Dygerts bed, Willman and Kolata, 1978) that is apparently absent in SSC-3. The more argillaceous character of the Platteville is evident in the wide swings of the deep induction log, as are shaly, cemented zones at 670 to 700 (base of Glenwood) and 890 (St. Peter) feet deep. Videocamera Imaging Water was observed entering the hole from around the outside of the casing (actually noticed in varying degrees in all three holes). The videocamera revealed considerable vugginess in the Galena from 340 to 470 feet deep; large vugs were particularly apparent from 424 to 432 31 Depth (ft) Elevation 841 ft 0- / / / \ 7 \ / / Clay, poor samples / \ Gravel, coarse (1??-140 ft) \ / 100- ? •"• o •" ' 'O . o • °.° ^ •140 200- Dolomite, argillaceous, gray blue; shale, dolomitic (140-180 ft) Shale, dark olive gray (180-279 ft) 279 300- czz 7 7 zrz 7=el 400- z Dolomite, pale yellow brown, fine to medium grained (279-510 ft) 7 T T~l zzz z_z 500- z A.~^^35 510 / / / Dolomite, light brown, fine grained (510-611 ft), bluish (510-530 ft), grayer (535-611 ft) ZZZ <5cD Q. 600- 7TT 611 o a> •A* . o o g « Sandstone, fine to grained (611-684 ft) CT3 medium o> c 684 700- O 800- Sandstone, fine to medium grained, rounded; chert (684-940 ft); cemented sand; shale partings (684 ft, 888-896 ft) CO 900- 'A A AA A A 940 A A A A A Chert, white; sandstone, white, cemented; dolomite, pink; shale, gray; (940-955 ft) A A AAA Kress Mbr Chert, oolitic, gray; siltstone, brown, red; shale, tan, brown, grey green (955-985 ft) 985 994 TD Eminence Fm Dolomite, light pinkish tan, sandy (985-994 ft) Figure 12 Stratigraphic column of SSC-1. 32 Depth (ft) 0' Resistivity (deep induction) Gamma Spontaneous potential Neutron porosity (compensated neutron) Figure 13 Selected geophysical logs from SSC-1. feet. Thin horizontal breakouts at 359, 372, and 381 feet probably represented thin clay or shale beds. Other vuggy intervals were encountered from 582 to 600 feet, but fewer vugs appeared between 600 and 616 feet. Several fractures were noted in the Galena-Platteville; long, semi-continuous fracture extending through most of the St. Peter Sandstone possibly represented stress release following drilling. The borehole was obstructed below a large breakout in shale at 984 feet. / detailed videocamera log is provided in Appendix B. 33 TEST HOLE SSC-2 Location: SW1/4, NW1/4, SW1/4, NW1/4, Section 32, T39N, R8E Du Page County Property: Fermi lab Surface Elevation: 753 feet Total Depth: 1080 feet Stratigraphy The stratigraphic column in figure 14 shows the lithologies and thick- nesses of the rock units encountered in Test Hole SSC-2. The hole pene- trated the Shakopee Dolomite, the New Richmond Sandstone, and terminated in the Oneota Dolomite. Encountered were 81 feet of glacial drift; 129 feet of gray-brown, fine-grained dolomite (Silurian); 155 feet of light to medium gray, blue-gray, fine-grained dolomite, dark olive-brown gray dolomite, and dark olive-brown shale (Maquoketa); 205 feet of pale yellow-brown, fine- to medium-grained dolomite (Galena Group); 116 feet of pale yellow-brown, fine-grained dolomite (Platteville Group); 254 feet of white, rounded, fine-grained sandstone (Ancell Group-- Gl enwood Formation and St. Peter Sandstone, including 23 feet of basal blue-green shale and dolomite of the Kress Member); 80 feet of light brown, fine-grained dolomite (Shakopee Dolomite); 35 feet of fine- grained, rounded white sand (New Richmond Sandstone); and 45 feet of light brown, cherty dolomite (Oneota Dolomite). Geophysical Logging Geophysical logs run by the ISGS in Test Hole SSC-2 included caliper, spontaneous potential, single point resistivity, natural gamma, neutron, and density. Dual induction, gamma ray, lithodensity, compensated neutron, long space sonic, and natural gamma ray spectroscopy were logged by Schlumberger. Figure 15 shows the gamma ray, dual induction (deep induction), spontan- eous potential, and neutron porosity logs recorded at SSC-2 by Schlumberger. Shale marking the Silurian/Maquoketa boundary is apparent in the gamma ray, induction, and neutron logs, and all four curves clearly delineate the change in porosity and density at the Maquoketa- Galena boundary. The deep induction log shows particularly well the relative lithologic homogeneity of the Galena Group, and the lesser degree of homogeneity of the Platteville Group. Although the boundary between the two groups is not clearly delineated, it is at an approxi- mate depth of 570 feet. The change of porosity and lithology at the Platteville-Ancell boundary is clearly shown by the induction and density logs. Inspection of all four geophysical logs suggests the complete absence of the Gl enwood at SSC-2, and its presence is not supported by samples. 34 The logs show the relative homogeneity of the St. Peter Sandstone, except for occasional shale or cemented zones. One such zone at 855 feet appears in all three test holes as evidenced by the gamma and induction logs. Collapse of the hole and total loss of circulation prevented logging past the Ancell Group boundary. A similar breakout and obstruction of the borehole occurred at the same stratigraphic interval in SSC-1. Videocamera Imaging the videocamera revealed large vugs in intervals from 147 to 183 feet, 209 to 213 feet, 480 to 494 feet, 506 to 521 feet, and showed the large breakout at 890 to 893 feet that presumably blocked the borehole. Several fractures were noted from 202 to 207 feet in the lower Silurian and from 230 to 233 feet in the upper Maquoketa. A detailed videocamera log is presented in Appendix B. Results of Core Sampling A total of 80 feet (four 20-foot cores) of core was recovered from SSC-2; rock was collected from depth intervals from 310 to 331.8 feet (Maquoketa), 410 to 427.75 feet, 480 to 499.6 feet (Galena), and 580 to 599.4 feet (Platteville). The core was carefully labeled and packed in boxes for transport. The lithology, fractures, bed spacing, Rock Quality Designation, and any unusual features of the core were described in the laboratory. The recovered core was then subjected to strength testing, including unconfined compression, indirect tensile, axial and diametral point-load, moisture content, specific gravity, compressive wave velocity, and Shore hardness. Table 11 shows representative average strength and associated property values for each core. The complete test results are on open file at the ISGS. 35 Depth (ft) Elevation 753 ft 0> / N 6 ^° - Clay, gray, coarse, sandy silty, with sand seams (0-46 ft, 52-68 ft) . . o c§ o Sand, coarse gravel (46-52 ft) °°o o o O <0 O Clay, brown, sandy silty, with sand and gravel (68-81 ft) 81 100- ~rrr z±z Dolomite (81-210 ft), light gray brown, fine grained, speckled black (90-115 ft) glauconitic (170-180 ft); clay present (gray and blue green), 7T7 Si browner near base (160-210 ft), particularly (190-210 ft) 200' CO ^ 210 Z-ZZ Dolomite, light medium gray to blue gray, fine grained, argillaceous (210-250 ft) Dolomite, dark olive brown gray, very argillaceous; shale, similar color, 300- ppT—J-— dolomitic (250-295 ft) Shale, dark olive gray, dolomitic (295-365 ft) t~t~i 365 400' TZZ zS2 Dolomite, pale yellow brown, fine grained; shale partings, blue green common, black-brown partings less common (365-570 ft) 500- s zZz z 2 z^ 570 Q. Z3Z O 600- Z== u Dolomite, pale yellow brown, some shale partings, blue green; chert, white 5z CO (570-686 ft) Z Z / JO Q. -686 700 s ccu o „ GO O. Sand, fine to medium grained; rounded dolomite, some rare (686-897 ft) 800- 0) c Q- < 900- -897 Kress Mbr Dolomite, light brown, fine grained; shale, blue green (897-920 ft) 23 - 920 Dolomite, light brown, fine grained; chert, white; pyrite rare (920-1000 ft) to o a7~z: CO 1000 1000 New Richmond Sand, fine to medium grained, rounded, floating grains, some cemented with calcite Sandstone (1000-1035 ft) -1035 ^S Dolomite, light brown ; chert, white (rare to common) ; sand present in some horizons / / c o (1035-1080 ft) 1080 TD °8 Figure 14 Stratigraphic column from SSC-2. 36 Depth (ft) Resistivity Gamma (deep induction) Spontaneous potential 1080 T.D. k Figure 15 Selected geophysical logs from SSC-2. 37 38 TEST HOLE SSC-3 Location: 1100E, 100S, NEc, Section 23, T38N, R6E, Kane County Surface Elevation: 688 feet Total Depth: 903 feet Stratigraphy The stratigraphic column in figure 16 shows the lithologies and depth of the rock units encountered in Test Hole SSC-3. The hole penetrated to the upper part of the Oneota Dolomite and encountered (top to bottom) 133 feet of glacial drift; 86 feet of gray-brown argillaceous dolomite and dark olive-brown shale (Maquoketa Group); 216 feet of pale yellow- brown, medium- to fine-grained dolomite (Galena Group); 109 feet of light brown, bluish and dark brown fine-grained dolomite (Platteville Group); approximately 90 feet of noncherty, white, fine- to medium- grained sandstone (Glenwood); approximately 215 feet of white, fine- to medium-grained sandstone with rare chert and occasional shale partings (St. Peter); and 52 feet of light pink-gray-brown, fine- to medium- grained dolomite (Oneota Dolomite). Geophysical Logging Geophysical logs run by ISGS in Test Hole SSC-3 included caliper, spontaneous potential, single-point resistivity, natural gamma radia- tion, neutron, and density. Dual induction, gamma ray, lithodensity, compensated neutron, long space sonic, and natural gamma ray spectros- copy were logged by Schlumberger. Figure 17 shows the gamma ray, dual induction (deep induction), spontaneous potential, and neutron porosity logs recorded at SSC-3. In both SSC-3 and SSC-1, the deep induction response curve exhibited inflections in the Galena at approximately the same stratigraphic interval, probably representing clay derived from volcanic ash deposits. The Galena appears extremely homogeneous on the deep induction log. The deep induction and gamma ray logs both show the Platteville to be more argillaceous than the Galena. In SSC-3, near the base of the St. Peter, a shaly or cemented zone recognizable in all three test holes is especially prominant. Videocamera Imaging The upper Galena contained abundant shale partings, about 5 per foot. Vuggy zones were encountered between 223 feet--top of Galena--and 301 feet, 337 and 342 feet, 309 and 375 feet, 379 and 392 feet, 415 and 439 feet, and 502 and 524 feet within the Galena-Platteville. Large vugs appeared between 513 and 524 feet. A vuggy interval in the Oneota lay between 888 and 891 feet. A few small fractures were evident; a one- inch breakout at a depth of 296 feet might represent the Dygerts clay bed mentioned in the discussion of SSC-1. A detailed description of the videocamera images is provided in Appendix B. 39 / Depth (ft) Elevation 688 ft 0- O o 'a o ,Oo ° o/ \ / <' Clay, brown gray, sandy, silty (0-42 ft) Sand, gravel, fine to coarse (42-128 ft) o o Clay, brown gray, sandy (128-133 ft) 100- o • T O '.<" \s /«\6 • 133 eg *: Q. o 3 Dolomite, very argillaceous; shale, dolomitic, gray brown (133-170 ft) ZJ O ^ Shale, dolomitic, brown to olive brown (170-219 ft) 200- £5 219 z3 300' Vz I / / Dolomite, pale yellow brown, fine to medium grained (219-435 ft) ; blue green, gray tEl shale partings, calcareous (275-400 ft) 400- & TZJ. T=J-TTT -435 Dolomite, light brown (435-544 ft), occasionally bluish, dark brown (435-460 ft, « o 475-510 ft) fine grained 500- ro (5 tg Q. z 544 O O Sandstone, fine to medium grained, rounded (544-630 ft) C T3 600- .92 S o<8 630 ^ ./>:•'•*• •A • - . • A • 700- # Sandstone, fine to medium grained, rounded; chert (630-851 ft) Shale partings, light gray (765-815 ft), green blue (830-851 ft) Dolomite, deep pink brown, fine grained, thin horizons (835-851 ft) r: /-•tt;. 800- •31a-1--1 C/) Ja ; -851 2 2 Dolomite, light pink-gray-brown, fine to medium grained; chert, white, o £ c o rare (851-903 ft); glauconite (895-903 ft) 900 ^ /A / Oo 903 TD Q Figure 16 Stratigraphic column from SSC-3. 40 - Depth (ft) 100 200- 300 400- J" 500- 600 700- 800- -J>_ 903 T.D. Resistivity (deep induction) Gamma Spontaneous potential Neutron porosity (compensated neutron) Figure 17 Selected geophysical logs from SSC-3. 41 REFERENCES Bateman, R. 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Kempton, 1971, Stratigraphy of the glacial deposits at the National Accelerator Laboratory site, Batavia, Illinois: Illinois State Geological Survey Circular 456, 21 p. LeRoy, L. W., D. 0. LeRoy, and J. W. Raese (eds.), 1977, Subsurface geology: Petroleum, Mining, Construction, Fourth Edition, Colorado School of Mines Press, Colorado School of Mines, Golden, CO, p. 304-336. Peebler, B., no date, Multipass Interpretation of the Full Bore Spinner: Schlumberger Well Service, 28 p. Pough, F. H., 1953, A Field Guide to Rocks and Minerals: The Riverside Press, Cambridge, MA, p. 137. 43 Pratt, H. R., A. D. Black, W. D. Brown, and W. F. Brace, 1972, The effects of specimen size on the mechanical properties of unjointed diorite: International Journal of Rock Mechanics and Mining Science, v. 9, no. 4, pp. 513-530. Rider, M. H., 1986, The Geological Interpretation of Well Logs: Blackie and Son Limited, London, England, 175 p. Schlumberger, 1984, Schlumberger Production Services Catalog: Schlumberger Well Services, 60 p. Schlumberger, 1985, Schlumberger Openhole Services Catalog: Schlumberger Well Services, 76 p. Visocky, A. P., M. G. Sherrill, and K. Cartwright, 1985, Geology, hydrology and water quality of the Cambrian and Ordovician systems in northern Illinois: Illinois State Geological Survey and Illinois State Water Survey, Cooperative Groundwater Report 10, 136 p. Visocky, A. P., and M. Schulmeister, 1988, Groundwater investigations for siting the Superconducting Super Collider (SSC) in northeastern Illinois: Illinois State Water Survey Circular 170. Wickham, S. S., W. H. Johnson, and H. D. Glass, 1988, Regional geology of the Tiskilwa Till Member, Wedron formation, northeastern Illinois: Illinois State Geological Survey Circular 543. Willman, H. B., and others, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p. Willman, H. B., and D. R. Kolata, 1978, The Platteville and Galena Groups in northern Illinois: Illinois State Geological Survey Circular 502, 75 p. 44 APPENDIX A: Logs of Test Holes* Test Hole SSC-1 Surface Elevation: 841 feet Thickness Depth (ft) (ft) 140 140 -glacial drift (120 to 140 ft), sand and gravel 150 -casing depth 160 -start of bedrock sampling Maquoketa Group 15 175 -dolomite, argillaceous, bluish gray; shale, similar, soft 10 185 -shale, dark brownish gray, dolomitic 5 190 -dolomite, argillaceous, gray brown 55 245 -shale, very dark gray brown, dolomitic, soft; some dolomite, very dark gray brown 30 275 -shale, very dark gray, less dolomitic Galena Group 75 350 -dolomite, fine grained, buff; rare shale, gray 5 355 -dolomite, as above; gray clay bed 85 440 -dolomite, fine to medium grained, buff; rare dolomite, fine grained, blue gray, brown; rare shale, dark gray 68 508 -as above, slightly calcareous; rare chert, white, more common at base Platteville Group 7 515 -dolomite, very fine grained, bluish buff 5 520 -dolomite, fine grained, buff; chert, white 17 537 -dolomite, very fine grained, bluish buff; dolomite, fine grained, buff; abundant pyrite 3 540 -dolomite, fine grained, buff 60 600 -dolomite, fine grained, medium to dark bluish brown; rare pyrite; chert, rare white to gray 5 605 -dolomite, fine grained, buff, calcareous 5 610 -dolomite, fine grained, buff, very sandy; some cemented sandstone, white, fine to medium grained Ancell Group, Glenwood Formation 1 611 -sandstone, white, round to subround, cemented, calcareous 54 665 -sand, white, round to subround; rare chert, white; very rare shale, gray 10 675 -sandstone, as above, cemented 3 678 -sandstone, as above, cemented; shale, bluish green, very calcareous; dolomite, bluish gray 680 -sandstone, as above, cemented, floating grains *Based on sample descriptions; adjusted to geophysical logs and videocamera imaging. 45 Test Hole SSC-1 (continued) Thickness Depth (ft) (ft) 685 -dolomite, bluish gray, very calcareous; shale, bluish green 690 -sandstone, white, cemented, black, red, green, pyrite? and unidentified materials St. Peter Sandstone 695 -sand, white, round to subround, fine grained, as above; shale, gray, soft, common 5 700 -sand, as above; no shale; rare pyrite 65 765 -sand, as above, some iron stained; pyrite, white; chert; gray shale generally present, not common 5 770 -sand, as above, coarse grained 45 815 -sand, as above, finer grained; shale, pyrite, and chert, present 20 835 -sand, as above, coarse grained, less well sorted 3 838 -sand, as above, cemented; calcite 42 880 -sand, as above; white chert common 5 885 -sand, as above, cemented; calcite 5 890 -sand, pink, cemented; dolomite, pink; pyrite; gray shale 45 935 -sand, white, fine to coarse grained, iron stained; white chert; pyrite Kress Member, St. Peter Sandstone 5 940 -sandstone, cemented (non-calcareous), pink 1 941 -dolomite, pink to brown; some pyrite; shale, gray, light gray 1 942 -shale, gray to white; weak, little carbonate 1 943 -sandstone, cemented, angular grains, with white chert 2 945 -chert, white, amorphous; some crystalline chert, tan 5 950 -chert, white to gray; some pyrite 5 955 -shale, brown to red to orange, laminated 5 960 -chert, oolitic, white to gray; little sandstone; siltstone 1 961 -siltstone, laminated, brown to red, sand (fine); some pyrite 1 962 -shale, red; dolomite, white 2 964 -chert (?), white to gray 3 967 -chert, oolitic; grayish to brown to white oolites, sand grain core 8 975 -sand, white; very fine to fine grained, slightly silty 3 978 -sandstone, cemented; tan to brown 5 983 -shale, gray to green Eminence Formation 11 994 -dolomite, sandy, light pink-to-tan, tan-to-gray T.D. 994 46 Test Hole SSC-2 Surface Elevation: 753 feet Thickness Depth (ft) (ft) 80 0-80 -glacial drift Silurian Dolomites 25 105 -dolomite, gray to light gray, fine to very fine,> some coarser grained, some iron staining, some "salt and pepper" dolomite 15 120 -dolomite, as above, calcareous 15 135 -dolomite, as above; rare pyrite 5 140 -dolomite, light brown, fine grained, bluish green clay 5 145 -dolomite, olive brown 25 170 -dolomite, medium gray to brown, fine grained; rare pyrite 10 180 -dolomite, as above, glauconitic, calcareous 30 210 -dolomite, as above Maquoketa Group 25 235 -dolomite, gray, some bluish, fine grained 15 250 -shale, dark gray blue, soft; some dolomite, as above 50 300 -predominantly shale, dark olive brown to olive gray, dolomitic; common dolomite, similar color, fine- grained; some pyrite; rare buff dolomite, blue shale 65 365 -shale, dark olive gray to brown; rare white chert Galena Group 10 375 -limestone, light buff, fine to medium grained; shale, gray; pyrite 25 400 -dolomite, as above; shale, bluish green 15 415 -dolomite, as above; shale, brownish black 165 580 -dolomite, as above; shale, bluish green, some brown; pyrite; white chert, rare Platteville Group 20 600 -dolomite, bluish buff, fine grained? (poor samples), white chert, bluish green shale; pyrite, rare 95 695 -dolomite as above, brown Ancell Group, St. Peter Sandstone 50 745 -sand, white, rounded, fine grained, slightly calcareous; rare white chert 20 765 -sand, as above, coarser 95 860 -sand, as above, fine 5 865 -sand, as above, abundant light gray shale 25 890 -sand, as above, fine 5 895 -sand, as above, iron stained 47 Test Hole SSC-2 (continued) Thickness Depth (ft) (ft) S hakopee Formation 40 935 -dolomite, light yellow brown, gray at base, fine grained; calcite crystals; bluish green shale; pyrite rare 935 -prominent bluish green shale bed 65 1000 -dolomite, light pink to brown, fine grained; pyrite rare New Richmond Formation 5 1005 -sand, fine, white 5 1010 -dolomite, white to light brown, abundant sand 10 1020 -sand, white, fine, rounded? 10 1030 -sandstone, cemented, calcareous, floating sand grains, poorly sorted, iron staining; dolomite, white, rare Oneota Formation 10 1040 -dolomite, white to pink, calcareous, sand abundant 41 1081 -dolomite, light pink to brown, fine grained; white chert, common YD io81 48 Test Hole SSC-3 Surface Elevation: 688 feet Thickness Depth (ft) (ft) 133 133 -glacial drift Maquoketa Group 8 140 -dolomite, very argillaceous, gray to brown gray; pyrite rare 25 165 -shale, dolomitic, brownish gray, similar to above; pyrite rare 5 170 -dolomite, argillaceous, light brown to tan, fine grained, bryazoan 5 175 -shale, slightly dolomitic, brownish gray, hard 5 180 -shale, dolomitic, gray 25 205 -shale, dolomitic, dark olive brown, hard 15 220 -shale, gray Galena Group 45 275 -dolomite, light yellow brown, fine to medium grained; pyrite rare to common; blue-green shale partings rare 160 435 -dolomite, calcareous, light pinkish brown, fine to medium grained; white chert Platteville Group 30 465 -dolomite, medium to dark bluish buff, dark blue mottling, very fine grained, pyrite rare 10 475 -dolomite, coarser than above, lighter, more brown in color; calcite crystals 45 520 -dolomite, \/ery fine grained, bluish, bluish to brown; some horizons much darker than others; blue mottling present 20 540 -dolomite, fine to medium grained, pinkish brown; rare white chert; white calcite Ancell Group, Glenwood Formation 5 545 -sandstone, white, cemented (dolomite), grains round to subround 55 600 -sand, white, frosted, rounded, well sorted, medium grained 40 630 -sand, as above, finer grained 49 Test Hole SSC-3 (continued) Thickness Depth (ft) (ft) St. Peter Sandstone 20 650 -sand, as above; white chert, common; pyrite, rare 25 675 -sand, as above, coarser grained; common; pyrite, rare 30 705 -sand, as above, finer grained 10 715 -sand, as above, coarser grained 15 730 -sand, as above, finer grained 20 750 -sand, as above, with fine-grained, cemented aggregates; rare dolomite, brown, fine grained 15 765 -sand, as above; pyrite, rare 60 825 -sand, white, frosted, rounded, some grains cemented; abundant to rare shale, gray; white chert, common; pyrite, rare 25 850 -sand, as above, iron stained; shale, green to gray, bluish green, common to rare; chert, white, red, common; dolomite, pinkish brown, fine grained, rare Prairie du Chien Group, Oneota Formation 5 855 -dolomite, light pinkish gray, some reddish purple, medium to coarse grained; pyrite, shale, rare 15 870 -dolomite, light pinkish brown, fine grained; rare white chert 25 895 -dolomite, light pinkish brown, fine grained; with light gray, coarsely crystalline dolomite aggregate 5 900 -dolomite, as above; glauconite, rare T.D. 903 50 APPENDIX B: Borehole Descriptions from Closed Circuit Television Test Hole SSC-1 Logged by R. Bauer (11-12-86) Depth (ft) - 151 Casing 151 - 279 Maquoketa: interbedded dolomite and shale. 279 Galena: top of Galena. 295 Top of water in borehole. 340 Galena becomes vuggy. Remains vuggy to about 470. 359 Horizontal fracture or breakout all around well wall. 372 Horizontal breakout of bentonite layer? 381 Horizontal breakout of bentonite layer? 424 - 432 Area of large vugs 2 to 4 inches across. 470 Becomes less vuggy but vugs continue to 555. 488 - 489 Fracture—small , vertical in one sidewall only. 492 Fracture--small, vertical in one sidewall only. 512 - 518 Color and texture change—darker and rougher from increase in horizontal shale partings. 522 - 555 Fracture — nearly vertical, open with pyrite crystals lining walls of fracture as shown at 522, 536, 538 and 555. Fracture starts in one side of borehole and exits borehole at 538 but parallels borehole to 542 as shown by small flat breakouts and disturbances in that side of borehole. At 542 fracture enters hole again and moves across borehole and exits on other side of borehole at 555 for a dip of about 87 degrees between 542 and 555. 555 Loose vugs. 559 - 562 Color and texture change—darker and rougher from increase in horizontal shale partings. 560 Fracture— horizontal opening. 566 - 572 Fracture— small , tight, mostly vertical --zig-zags around on one side wall only. 568 - 581 Color and texture— change— darker and rougher from increase in horizontal shale partings. 582 - 600 Vuggy section. 600 - 616 Vugs— less vugs than above; vugs at 616. 665 - 684 Fracture— vertical , thin, tight. 680 - 696 Color and texture change—darker and rougher from increase in horizontal shale partings. 708 - 954 Fracture—vertical, thin, tight, mostly seen in one sidewall. From 711 to 716 a parallel fracture is found 45 degrees away. From 717 to 760 there is a parallel thin fracture about 90 degrees away. At 766 to 776 joined by another parallel fracture across the entire borehole— wider at 864 to 867 wider and on both sides of borehole. 890 - 895 Texture and color change in sidewalls, fracture is continuous through it. Similar to shaly section; not horizontal fractures— only breakout of shale. fcltfRAh JUN1 3 i 51 ILL STATE BEOLOGIHAl W Test Hole SSC-1 (continued) Depth (ft) 896 - 899 Fracture—parallels continuous fracture and is found about 30 degrees away. 944 _ 947 Texture and color change in sidewalls, same as 890 to 895 shaly section with breakout of some shale. 954 Lost fracture that started at 708. 958 - 960 Color and texture change—darker and rougher from increase in horizontal shale partings. 970 Start of another texture and color change at 890 and 944. Rougher irregular sidewalls with darker color. Probably shaly section with breakouts of shale. 982 Enlargement and elongation of borehole and then opens up to much bigger enlarged breakout; blockage of hole by debris at 984. 52 Test Hole SSC-2 Logged by R. Bauer (7-87) Depth (ft) Footage markers start 4 feet above ground surface. 67 Static water level. 88 Bottom of casing. General description--! ight color dolomite or limestone as shown by vugs, smooth borehole walls, and some crystalline appearance. 92 Horizontal breakout—possible shale layer. 107 - 110 Increasing amounts of shale partings. 123 - 136 Increasing amounts of shale partings. 147 - 183 Zone of large vugs up to 4 to 6 inches across. 194 - 195 Fracture sloping 45 degrees across hole. 202 - 204 Several vertical fractures. 206 - 207 Several fine vertical fractures that begin and end at shale partings. 209 - 211 Large vugs. 212 - 213 Large vugs all around hole, some up to diameter of hole. 221 Start of light and dark bands—Maquoketa Shale Group. 230 - 233 Fractured zone with multiple fractures with various dips and directions. 240 - 311 Increasing amount of dark material (shale) from 50 percent at 240, to 80-90 percent at 311. 364 Top of Galena--light color, small vugs, 1/2 inch in diameter and less. 376 - 378 Shale partings--about one per foot. 386 - 413 Shale partings--many per foot. 413 - 442 Few shale partings, more crystalline, shiny crystal faces on wall, massive. 442 - 466 Partings--several per foot, then many per foot at 448. 488 - 494 Vugs--increasing in size and numbers. 494 Back to massive, small vugs. 506 - 521 Large scattered vugs. 531 - 538 Vuggy. 541 - 547 Shale partings—several per foot. 553 - 556 Fracture starts and ends on same side of sidewall. 580 - 582 Shale partings. 586 - 588 Many shale partings per foot. 593 - 607 Many shale partings per foot. 607 - 626 Back to massive. 626 - 632 Shale partings about one per foot. 632 - 653 Many shale partings per foot. 653 Back to massive with small vugs. 858 Borehole breakout—all around hole. 885 - 890 Cracks in mud buildup on walls of hole. 890 - 893 Large breakout— three to four times diameter of borehole. 896 - 899 Three to four large voids—vugs? on one side of borehole, some fractures associated with voids. 899 Bottom of hole in large void full of rock debris. 53 Test Hole SSC-3 Logged by R. Bauer (7-87) Depth (ft) Footage markers start 2.5 feet above ground surface. 145 Bottom of casing—water coming in around casing, is flowing down walls of borehole. Bands of dolomite and shale layers — 50 percent to 50 percent, Maquoketa Shale Group. 146 Several jets of water shooting across borehole. 147 Five jets shooting across borehole. 154 Static water level. Shale amount increases downward to 70--80 percent at 190. 223 Top of Galena— small breakout all around borehole at contact. Dolomite is massive and vuggy with 1-inch vugs. 259-277 Shale partings about one to two per foot, numbers increasing downward to five per foot at 270. 277 Back to massive, but more vuggy than massive section above 286 More vuggy. 296 1-inch thick breakout all around hole--Dygerts? shale layer? vertical fractures from near shale layer down to 301. 301 Less vuggy with one to two shale layers per foot. 337 - 342 Vuggy zone. 338 - 344 Vertical crack. 342 - 369 Massive, very few shale partings and vugs. 369 - 375 Vuggy. 379 - 392 Vuggy, large vugs up to 1 to 1.5 inches in diameter. 409 Several fractures in one sidewall. 415 - 439 Vuggy. - 441 447 Many shale partings—overall , rock darker in color. 447 - 462 Back to massive, lighter color, vuggy. 462 - 479 Light in color, one to three partings per foot. 492 - 502 Darker again with many partings per foot. 502 - 524 Vuggy. 513 - 524 Large vugs, more massive and light in color. 524 - 533 Massive, light color. 549 Massive, no vugs, light color top of sandstone? 634 - 650 Darker in color, dark partings. 650 Back to light color. 781 - 783 Darker— partings? 783 - 853 Rougher sidewalls. 853 Contact: Ancell/Oneota, borehole breakout around entire hole. 853 - 891 Very vuggy. 896 Large 4- to 5-inch void, one side of hole. 904 Bottom of hole— full of rubble. 54 APPENDIX C: Geophysical Logging Different types of geophysical tools were used in this study. Several other texts describe these tools and applications in much greater detail (Bateman, 1985; Brock, 1984; Brock, 1986; Curtis, 1966; Dobrin, 1976; Dresser Atlas, 1981; Gearhart, 1983; Hallenburg, 1984; Helander, 1983; Kovacs and Assoc, 1981; Leroy et al., 1983; Pebbler, no date; Rider, 1986; Schlumberger, 1984; Schlumberger, 1985). Gamma Ray Log (GRL) As its name suggests, the GRL tool is designed to detect naturally occuring gamma rays. Gamma rays are random, high-energy electromagnetic waves emitted during the decay of unstable radioisotopes. The radioiso- topes normally found in rocks are potassium-40 and the products of the uranium and thorium decay series. The GRL tool discussed here cannot differentiate the contribution of each individual radioisotope to the total intensity of gamma radiation. The detector of the tool normally consists of a sodium iodide (Nal) crystal optically coupled to a photomultipl ier tube. Atoms of the Nal crystal absorb gamma ray collision energy that raises their electrons to a higher energy state. When the excited electrons lose this acquired energy and fall back into their rest state, they give off light that is converted to a voltage pulse through the photomultiplier tube. These pulses are transmitted uphole and converted, on the appropriate scale, to a measure of the gamma ray intensity. Due to the high natural concentration of potassium-40 in clay minerals, shales generally exhibit higher gamma ray intensities than sandstones and carbonates, which commonly have relatively low concentrations of clays and other radioactive constituents. In a simplified sense, this difference in gamma ray intensity allows identification of various lithologies (thus allowing correlation of lithologic units) and the determination of a rock unit's shale volume. Sonic Log (SL) The sonic log is an acoustic device whose response is a function of the factors that affect the passage of acoustic waves. The measurements taken from the SL tool are the direct result of the propagation of the acoustic (elastic) waves through the borehole environment. The two waves of importance to the SL tool are the compressional (longitudinal) and the shear (transverse) waves. The initial energy to produce the acoustic waves is provided by the transmitter (T) portion of the tool. As a compressional wave trans- verses the borehole fluid and strikes the borehole interface, a shear wave is produced. Therefore, as the compressional wave traverses from the transmitter (T) to the receiver (R) on the tool, the compressional wave itself generates a shear wave that can, in this manner, be detected by the receiver circuitry. 55 Various .transmitter-receiver (T-R) configurations are available. The T- R array is chosen to account for abnormalities in the borehole envi ronment--that is, washouts and tool tilting. The standard T-R configuration is incorporated into the borehole compensated sonic logging (BCSL) tool. The long spaced sonic logging (LSSL) tool incorporates a longer T-R spacing than the BCSL tool. The LSSL tool is affected by a zone farther away and less distorted by drilling operations than the zone at the borehole interface. This instrument has been used for shear wave analysis, which when combined with compressional wave data results in an evaluation of some of the formation's strength characteristics, such as the pressure required to fracture the formation and the formation's elastic properties. If tfi is the time taken to travel through the pore space (fluid travel is the time taken to travel through the matrix, the total time) and t ma travel time" will be t (the travel time recorded by the tool), and the porosity (Ogre) can be represented by the Wyllie time-average equation: = t t °BCS (* " ma)/( fl " W The compressional wave (p-wave) takes the path of least resistance. Areas of isolated (not interconnected) pockets of porosity, as would normally be found in the case of secondary porosity, will not have a pronounced effect on the travel time of the p-wave. By comparing the sonic log data with data from a tool that is influenced by the total porosity (both primary and secondary), the amount of secondary porosity present can be estimated. The following equation applies to this situation, = + °tot °sec ^prirn Density Log (DL) The Density Log (DL) utilizes a focused gamma ray source, normally cesium-137, which emits gamma rays into the formation from a pad assembly forced against the borehole wall via a back-up arm. The gamma rays interact with the electrons in the material opposite the focused source mainly through Compton scattering. This results in the gamma ray losing energy at each collision. The intensity of the back-scattered gamma ray is then measured by the gamma ray detectors (usually two). The measured gamma ray intensity is a function of the electron density of the formation. As the electron density of the formation increases, the probability of collision increases resulting in reduced gamma ray intensity measured by the gamma ray detectors. The electron density, , has been related to the bulk density, by the following equation, p e p^, = (2Z/A) p e p b where, Z = the atomic number or the number of electrons per atom, and A = the atomic weight. 56 In most cases, the ratio, 2Z/A, is approximately equal to 1.0. There- fore, = Pl, and the apparent bulk density response of the tool is a p e response to the bulk density, , of the formation material opposite the p b tool. A two-detector density log, or compensated density log (CDL), is the one of concern here. The two-detector configuration allows for the compen- sation of the mudcake's effect on CDL tool response. In this way, an accurate total porosity measurement is obtained. This can be compared to BCSL porosity to obtain an estimate of secondary porosity or cross- plotted with the BCSL or CNL porosities to produce lithologic and total porosity determinations. Spectral Gamma Ray Log (SGRL) Whereas the GRL tool just measures the number of emissions from natural occurring radioisotopes, the SGRL tool measures both the number and the energy level of the emissions. The natural gamma radioactivity of geologic formations is basically attributed to the presence of three radioisotopes, or their derivatives. These isotopes are potassium-4, uranium-238, and thorium-232, which each encompass a specific energy level range. By measuring the number of emissions that fall into the range, a determination of isotopic percent- ages can be made. The spectral windows are centered at the following energy levels for each isotope: potassium-40, 1.46 MeV; uranium-238 (Bi-214), 1.76 MeV; thorium-232 (TI-208), 2.62 Mev. Potassium-40 activities are measured directly, and the concentration of total potassium is calculated from the isotopic abundance of potassium-40. However, uranium-238 and thorium-232 do not have clear peaks with their disintegrations. Therefore, activities of these iso- topes are determined by measurements of the activities of the derivative isotopes, Bi-214 and TI-208. Concentrations of the original isotopes are calculated from an assumption of radioactive equilibrium between parent and daughter nuclides. The terms equivalent uranium and equiva- lent thorium are used in reference to the concentrations that are not measured directly. Some applications of the SGRL include determining radioisotopic ratios to help interpret complex lithologies, correlating strata, and evalu- ating the potential radioactive material resource potential. 57 ACKNOWLEDGMENTS This study was conducted by the SSC Geological Task Force assisted by other staff of the Illinois State Geological Survey. Principal funding was provided by a special appropriation from the Illinois General Assembly to the Illinois Department of Energy and Natural Resources (IDENR) and administered through the University of Illinois. All aspects of the SSC work have had the enthusiastic support of the Governor of Illinois, James R. Thompson, and the Director of IDENR, Don Etchison. Many individuals and groups have contributed to the success of the test drilling portion of the SSC study. The project contractors, Layne Western Company of Aurora, Illinois, and Rock and Soil Drilling Corporation of Bartlett, Illinois, have provided excellent service. Kaneland Vocational Center, Big Rock Township, and Fermi National Accelerator Laboratory granted access to their property for test drilling, hydrogeologic tests, and water level measurements. Staff of the Illinois State Water Survey in Batavia conducted the pump test at SSC-1, then continued to monitor water levels in the piezometers every month. Within the Geological Survey many of the staff have contributed advice, expertise, and services. Dr. John P. Kempton, head of the Geological Task Force, provided valuable insight and guidance. Jacquelyn L. Hannah, also of the Geological Task Force, compiled data and maps and prepared illustrations. Three members of the Groundwater Section assisted with the fieldwork: Philip C. Reed conducted geophysical logging on all test holes; Robert H. Gilkeson and Stephen H. Padovani collected water samples from SSC-1. Joanne Klitzing and Gloria Merrick typed various drafts of the manuscript and final copy for the publication. Stephen S. McFadden, from the Groundwater Section, and Paul C. Heigold and Michael L. Sargent, both from the Basin Analysis Task Force, critically reviewed the manuscript. The ISGS Environmental Geology report was prepared by the Publications, Graphics, and Photography Unit. 58 HECKMAN |±l BINDERY INC. |§| JUN97 Bound.To -iW N.MANCHESTER, INDIANA 46962