fU 65 • IM120 jrn ia to J&l^ SUA Wj- Availability of the Herrin Coal for Mining in Illinois Colin G.Treworgy, Christopher P. Korose, and Christine L. Wiscombe Illinois Minerals 120 2000 George H. Ryan, Governor Department of Natural Resources ILLINOIS STATE GEOLOGICAL SURVEY William W. Shilts, Chief Natural Resources Building 615 East Peabody Drive Champaign, IL 61 820-6964 «-*• tf* x ... w 0'>' v* LIBRARY. Availability of the Herrin Coal for Mining in Illinois Colin G. Treworgy, Christopher P. Korose, and Christine L. Wiscombe Illinois Minerals 120 2000 George H. Ryan, Governor Department of Natural Resources ILLINOIS STATE GEOLOGICAL SURVEY ^»«* William W.Shilts, Chief ••" ^ Natural Resources Building * \ V^ 615 East Peabody Drive ^>?> „% Champaign, IL 61 820-6964 v -» u * % " (217)333-4747 \V*^ ACKNOWLEDGMENTS We are especially appreciative to the following mining experts who gave us information on criteria that limit the availability of coal: Manny Efframian, Tom McCarthy, David Johnson, George Martin, James Niemeyer, and Monna Nemecek, AMAX Coal Company; Greg Bieri and Philip Deaton, Arch Minerals; Dan Pilcher, Arclar Coal Company; Philip Ames, Bruce Dausman, Christopher Engleman, and Christo- pher Padavic, Black Beauty Coal Company; Brent Dodrill, James Hinz, Edward Settle, and Randy Stockdale, Consolidation Coal Company; S.N. Ghose, Dana Meyers, Marvin Thompson, and John Williams, Cyprus-AMAX Coal Company; Michael Caldwell, Neil Merryfield, and Roger Nance, Freeman United Coal Mining Company; Dan Ganey and Thomas Denton, Kerr-McGee Coal Company; Alan Kern, Michael Meighan, and John Popp, MAPCO Coal Inc.; James Grimm, Midstate Coal Company; Jeffrey Padgett, Monterey Coal Company; Eric Quam, Old Ben Coal Company; Michael Anderson, Vick Daiber, Marc Silverman, and Grady White, Peabody Coal Company; Robert Gullic and Walter Lucus, Sahara Coal Company; Steve Short and Dennis Oliver, Sugar Camp Coal Company; Scott Fowler and Guy Hunt, Turris Coal Company; Douglas Dwosh, Kenneth Ginard, and David Thomas, Weir International Mining Consultants; Daniel Barkley and Dean Spindler, Illinois Office of Mines and Minerals; and Robert Bauer, Illinois State Geological Survey. This project was supported by the U.S. Geological Survey, Department of the Interior, under the following agreements: 1 4-08-0001 -A0773, 1 4-08-0001 -A0841, 1 434-92-A0940, 1434-93-A1137, 14-94-A1266, 1434- 95-A01346, 1434-HQ96AG-01460, 1434-HQ97AG-01759, 1434-98HQAG-2015and 1434-99HQAG-0081. We especially thank Harold J. Gluskoter and M. Devereux Carter of the USGS and Heinz Damberger of the ISGS for their guidance and support. This study utilized a number of databases compiled over many years by Coal Section staff members. Cheri Chenoweth assisted with the mapping of areas of Anvil Rock Sandstone and compiling production figures. Margaret Bargh, Daniel North, and Valerie Straayer updated the mined areas. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government. This manuscript is published with the understanding that the U.S. Government is authorized to reproduce and distribute reprints for governmental use. The Illinois State Geological Survey considers its publications to be in the public domain. Cover photo: Undercutting the Herrin Coal, Old Ben Mine No. 9, Franklin County, Illinois. Editorial Board Jonathan H. Goodwin, Chair Michael L. Bamhardt John H. McBride B. Brandon Curry Donald G. Mikulic Anne L. Erdmann William R. Roy David R. Larson ILLINOIS Printed by authority of the State of Illinois/2000/500 © Printed with soy ink on recycled paper CONTENTS ACKNOWLEDGMENTS ii EXECUTIVE SUMMARY 1 INTRODUCTION 2 Coal Resource Classification System 3 Geology and Mining of the Herrin Coal 3 Quality of Coal 4 Quadrangle Studies 8 Sources of Data and Limitations of Maps 8 TECHNOLOGICAL AND LAND-USE FACTORS THAT AFFECT THE AVAILABILITY OF COAL FOR MINING 11 Surface-Minable Coal 15 Depth of Seam 15 Thickness of Seam 15 Stripping Ratio 15 Thickness of Bedrock and Unconsolidated Overburden 15 Size and Configuration of Mining Block 17 Land Use 19 Abandoned Mine Workings 19 Surface Mining of Multiple Seams 19 Underground Minable Coal 25 Depth of Seam 25 Thickness of Seam 25 Thickness of Bedrock and Unconsolidated Overburden 25 Thickness of Interburden Between Seams 27 Faults 30 Igneous Dikes 30 Partings 32 Walshville Channel and Energy Shale 34 Anvil Rock Channel and Sandstone Overlying Coal 36 Size and Configuration of Mining Block 39 Land Use 39 Abandoned Mine Workings 40 Closely Spaced Oil Wells 40 Potential Land-Use Conflicts 41 AVAILABLE RESOURCES 41 Coal Available for Underground Mining 43 Coal Available for Surface Mining 47 CONCLUSIONS 48 REFERENCES 50 APPENDIX 1 Source maps for coal resources 53 FIGURES 1 Extent of the Herrin Coal in the Illinois Basin 3 2 North-south cross section of the Pennsylvanian System in Illinois 4 3 Depth of the Herrin Coal 5 4 Remaining coal resources in the Illinois Basin 6 5 Annual production of the Herrin Coal in Illinois 6 6 Thickness of the Herrin Coal 7 7 Rank and heat content of the Herrin Coal 8 8 Sulfur content of the Herrin Coal 9 9 Chlorine content of the Herrin Coal 10 10 Quadrangle study areas used to identify criteria for coal available for mining 12 11 Stripping ratio of the Herrin Coal 16 12 Problems encountered in surface and underground mines that have overburden consisting of thick unconsolidated sediments over thin bedrock 17 13 Thickness of unconsolidated overburden in counties with surface-minable resources of the Herrin Coal 18 14 Towns in the vicinity of the Herrin Coal 20 15 State and federal highways in the vicinity of the Herrin Coal 21 16 Railroads in the vicinity of the Herrin Coal 22 17 Pipelines in the vicinity of the Herrin Coal 23 18 Parks and natural areas in the vicinity of the Herrin Coal 24 19 Floor squeeze in an underground mine in the Herrin Coal, Zeigler No. 5 Mine, Douglas County 25 20 Zones used to assign minimum thickness of bedrock overburden for underground mining of the Herrin Coal 27 21 Thick limestone sequence above the Herrin Coal, River King Pit No. 3, St. Clair County 27 22 Thickness of bedrock overburden, Herrin Coal 28 23 Ratio of the thickness of bedrock to unconsolidated overburden, Herrin Coal 29 24 Effect of interburden thickness on the minability of coal seams 30 25 Areas of Herrin Coal restricted because of the thickness of interburden between overlying or underlying seams 31 26 Cross section illustrating multiple, parallel faults displacing a coal seam 32 27 Highly fractured roof strata adjacent to a fault displacement, Peabody No. 44 Mine, Saline County 32 28 Unmined areas adjacent to one of the faults in the Wabash Valley Fault System 32 29 Areas of the Herrin Coal affected by faults and igneous dikes 33 30 Shale partings in the Herrin Coal near the Walshville Channel, Old Ben No. 1 1 Mine, Franklin County 34 31 Rib rashing in the Herrin Coal 34 32 Examples of partings in the Herrin Coal in the Nokomis Quadrangle 35 33 Areas of adverse mining conditions in the Herrin Coal near the Walshville Channel 35 34 Core of the laminated siltstone and shale facies of Energy Shale, Douglas County 36 35 Large roof fall in laminated Energy Shale, Jefferson County 36 36 Extensive roof bolting used to hold Energy Shale roof in an area disrupted by slump-like features 37 37 Patterns of underground mining and type of roof strata, west-central Illinois 37 38 Areas of the Herrin Coal with Anvil Rock Sandstone within 5 feet of the roof 38 39 Schematic cross section showing the relationship of the Anvil Rock Sandstone to other stratigraphic units 39 40 Closely spaced oil wells, Salem Oil Field, Marion County, ca.1 943 40 41 Underground mine workings in an area of closely spaced oil wells 41 42 Areas of the Herrin Coal containing closely spaced oil wells 42 43 Availability of the Herrin Coal for mining in Illinois 43 44 Availability of the Herrin Coal by thickness category 43 45 Availability of the Herrin Coal by reliability category 43 46 Availability of the Herrin Coal for underground mining 44 47 Areas of Herrin Coal available for underground mining 46 48 Availability of the Herrin Coal for surface mining 47 49 Areas of the Herrin Coal available for surface mining 49 TABLES 1 Availability of the Herrin Coal for mining in Illinois 1 2 Resources of the Herrin Coal in individual quadrangles studied 11 3a Criteria used to define the Herrin Coal available for surface mining in this study and previous quadrangle studies 13 3b Criteria used to define the Herrin Coal available for underground mining in this study and previous quadrangle studies 14 4 Minimum bedrock overburden and minimum bedrock thickness to drift ratio thickness for underground mining of the Herrin Coal 26 5 Average total width of fault zone assumed to be unminable 33 6 Availability of the Herrin Coal by thickness category 43 7 Availability of medium- and low-sulfur Herrin Coal by mining district 44 8 Availability of the Herrin Coal by reliability category 44 9 Resources of the Herrin Coal available for underground mining 45 10 Resources of the Herrin Coal available for surface mining 47 Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/availabilityofhe120trew EXECUTIVE SUMMARY Of the 88.5 billion tons of original resources of Herrin Coal in Illinois, 79 billion tons or 89% remain, the largest remaining coal resource in the state. The other 9.4 billion tons have been mined or lost during the almost 200 years of mining Illinois coal. The degree to which this remaining resource is utilized in the future depends on the availability of deposits that can be mined at a cost that is competitive with other coals and alternative fuels. This report identifies those resources that have the most favorable geologic and land-use characteristics for mining, shows the probable trend of future mining of these resources, and alerts mining companies to geologic conditions that have the potential to negatively impact mining costs. Approximately 58% of the original Herrin Coal resources (51 billion tons) is available for mining (table 1). "Available" means that the surface land use and geologic conditions related to mining the deposit (e.g., thickness, depth, in-place tonnage, stability of bedrock overburden) are comparable with those of other coals currently being mined in the state. Of these resources, 21 billion tons are 42 to 66 inches thick, and 30 billion tons are greater than 66 inches thick. An additional 3 billion tons of the Herrin Coal resources are available but have geologic or land-use conditions that are potential restrictions making them less desirable for mining. Technological factors (geologic conditions and economic parameters such as size of reserve block) restrict mining of 24% of the resources, and land-use factors (e.g., towns, highways) restrict mining of 4% of the resources. The available resources are primarily located in the central and southern portions of the state and are well suited for high-efficiency longwall mining. The resources are relatively flat-lying; have a consistent thickness over large areas; are relatively free of faults, channels, or other geological anomalies; are located predominantly in rural areas free from oil wells and other surface development; and are in minable blocks of hundreds of millions of tons. Whether or not the resources are ultimately mined is still dependent on a variety of other factors that have not been assessed, including the willingness of local landowners to lease the coal, demand for a particular quality of coal, accessibility of transportation infra- structure, proximity of the deposit to markets and cost, and availability of competing fuels. About 74 billion tons of the remaining Herrin Coal resources have greater than 1.67 pounds of sulfur per million Btu and are therefore mostly suited for the high-sulfur coal market. Although only 9% of the original resources had a sulfur content of less than 1 .67 pounds per million Btu, almost one-third of the past mining has been concentrated in these deposits. About 6 billion tons of this lower sulfur coal remain, and about half of this is classified as available or available with potential restrictions. For the most part, these lower sulfur resources are too deep for surface mining and will have to be mined by underground methods. Technological factors, particularly seam thickness and thickness of bedrock cover, are the pri- mary restrictions on mining these lower sulfur deposits. About 5% of these resources are available but potentially restricted by land use because of eastward expansion of development in the St. Louis metro- politan area. Table 1 Availability of the Herrin Coal for mining in Illinois (billions of tons). Total Potential minina method 1 Sulfur 2 Surface Underground <1.67 >1.67 Original 88.5 14.9 86.5 8.4 80.1 Mined 9.4 (11) 3 3.1 (21) 8.4(10) 2.7(32) 6.8 (8) Remaining 79.0 (89) 11.8(79) 78.1 (90) 5.7(68) 73.6 (92) Available 51.0(58) 2.2(15) 49.3 (57) 2.9(34) 48.1 (60) Available with conditions 3-1 (3) 0.2 (2) 3.3 (4) 0.3 (4) 2.7 (3) Technological restrictions 21.1 (24) 6.8 (45) 21.4(25) 2.3(27) 19.1 (24) Land-use restrictions 3.8 (4) 2.6(17) 4.1 (5) 0.2 (3) 3.7 (5) 'Surface and underground resources do not add to the total because coal that lies between 40 and 200 feet deep is included in both categories. 2 Pounds per million Btu. 3 Numbers in parentheses are percent of original resources. Most of the available Herrin Coal resources will have to be mined by underground methods. Of the 86 billion tons of original resources that are at least 40 feet deep (and therefore potentially minable by un- derground methods), 57% (49 billion tons) is available for underground mining. An additional 4% (3 bil- lion tons) is available but with potential restrictions that make the resources less desirable. These potential restrictions include the presence of closely spaced oil wells, less stable roof strata, or close proximity to developing urban areas. The major technological factors that restrict underground mining are unfavorable thicknesses of bedrock and unconsolidated overburden (9% of original resources), coal less than 42 inches thick (8%), and thin interburden between the Herrin Coal and an overlying or under- lying seam (4%). Land use restricts underground mining of 5% of the original resources, and 10% has already been mined or lost in mining. Only about 15 billion tons of the original Herrin Coal resource lie at depths of less than 200 feet and are potentially minable by surface methods. Of these resources, 21% has already been mined (3 billion tons), and 1 5% (2 billion tons) is available for surface mining. Land-use factors, primarily towns, restrict 17% of the resources. Technological factors, primarily stripping ratio and thick unconsolidated material, restrict 45% of the surface-minable resources. To avoid high mining costs resulting from unfavorable geologic conditions, companies seeking sites for underground mines should avoid areas with the following conditions: thick drift and thin bedrock cover, close proximity to the Walshville or Anvil Rock Channels or faults, areas of closely spaced oil wells and areas at the margins of the Energy Shale or closely overlain by Anvil Rock Sandstone. Areas with low- cost, surface-minable resources (areas with low stripping ratios that are free of conflicting land uses) are limited and will only support small, short-term operations. This report is the second of a series that explains the availability of coal in Illinois for future mining. A previous report evaluated the availability of the Springfield Coal for mining (Treworgy et al. 1999a). These two statewide assessments are based on earlier reports that evaluated the availability of coal in 21 study areas. The study areas were 7.5-minute quadrangles that were representative of mining condi- tions found in various parts of the state. Coal resources and related geology were mapped in these study areas, and the factors that restricted the availability of coal in the quadrangles were identified through interviews with more than 40 mining engineers, geologists, and other mining specialists repre- senting 17 mining companies, consulting firms, and government agencies active in the Illinois mining in- dustry. The major restrictions identified in these individual study areas were used for the statewide assessments of the availability of the Herrin and Springfield Coals for mining. INTRODUCTION Accurate estimates of the amount of coal resources available for mining are needed for planning by federal and state agencies, local communities, utilities, mining companies, companies supplying goods and services to the mining industry, and other energy consumers and producers. Current inventories of coal resources in Illinois provide relatively accurate estimates of the total amount of coal in the ground (e.g., Treworgy et al. 1997b), but the actual percentage of the total having geologic and land-use condi- tions favorable for mining is not well defined. Environmental and regulatory restrictions, the presence of towns and other cultural features, current mining technology, geologic conditions such as unstable roof strata, and other factors significantly reduce the amount of coal available for mining. The United States has enormous resources of coal.There is little concern that a shortage of coal could develop in the foreseeable future. The important issues for society are (1) where the greatest resources that are most favorable for mining are located and (2) how they will be extracted (McCabe 1998). Rec- ognizing that a significant difference exists between the reported tonnage of total coal resources and the tonnage legally or practically restricted from mining by various land-use and geologic conditions, the United States Geological Survey (USGS) initiated a program in the late 1980s, in cooperation with state geological surveys, to assess the amount of available coal in the United States (Eggleston et al. 1990). As part of this ongoing effort, the Illinois State Geological Survey (ISGS) is assessing the avail- ability of coal resources for future mining in Illinois. This report assesses the Herrin Coal resources in Illinois, identifies those resources that have geologic and land-use characteristics most favorable for mining, shows the probable trend of future mining of these resources, and alerts mining companies to geologic conditions that potentially can have a negative impact on mining costs. Coal Resource Classification System The ISGS follows the terms and definitions of the USGS coal resource classification system (Wood et al. 1983). With minor modifications to suit local conditions, these definitions provide a standardized ba- sis for compilations and comparisons of nationwide coal resources and reserves. The term "original resources" refers to the amount of coal originally in the ground prior to any mining. In past reports, the ISGS has defined "resources" as all coal in the ground that is 18 or more inches in thickness and lying less than 150 feet deep or all coal 28 or more inches thick lying at any depth. In this report, the ISGS defines "surface-minable coal" as all coal in the ground that is 18 or more inches thick and lying less than 200 feet deep and "underground-minable coal" as all coal 28 inches or more thick and lying 40 or more feet deep. The USGS and other states use 1 4 inches (not 1 8 or 28) as the mini- mum thickness for resources. This difference in definitions does not significantly affect the resource totals for the Herrin Coal, which is commonly thicker than 28 inches throughout the area of the state where it has been mapped. Although not yet formally part of the resource classification system, in recent years, the USGS and many state surveys have made efforts to divide remaining resources into two categories: restricted and available (Eggleston et al. 1990). "Restricted resources" are those that have some land-use or techno- logical restriction that makes it unlikely they will be mined in the foreseeable future. Land-use restric- tions include manmade or natural features that are illegal to disturb by mining or that make mining impractical. Technological restrictions include geologic or mining-related factors that negatively impact the economics or safety of mining. "Available resources" are not necessarily economically minable at the present time but are expected to have mining conditions comparable with those currently being suc- cessfully mined. Determining the actual cost and profitability of these deposits requires further engineer- ing and marketing assessments. In this study, the ISGS uses an additional category called "available with potential restrictions." This term designates resources that are not restricted by the land-use or technological restrictions, but that have some known special condition that makes them less favorable for mining. Close proximity to rap- idly developing urban areas, the presence of some but not too many oil wells, and potentially unstable roof conditions are examples of potential restrictions that have resulted in resources being placed in this category. In this study, therefore, remaining resources = resources restricted by land use + resources restricted by technology + resources available with potential restrictions + available resources. The USGS classification system uses the terms "measured," "indicated," and "inferred" to indicate the reliability of resource estimates based on the type and density of data (Wood et al. 1983). The ISGS uses similar categories, which, in previous reports, have been called Class la, Class lb, and Class Ma (Treworgy et al. 1997b). Because these earlier ISGS categories are essentially equivalent to the USGS categories, the USGS terminology is used in this report. Collectively, the resources in these three categories are termed "identified resources" to distinguish them from resources based on less reliable estimates. In this report, the term "resources" refers to identified resources as defined by Wood et al. (1983). Geology and Mining of the Herrin Coal The Herrin Coal underlies about two-thirds of Illinois as well as portions of western Indiana and Kentucky (fig. 1). In some parts of Indiana the Herrin Coal is thin and has been consid- ered to be a lower bench of the Hymera Coal (Treworgy et al. 1999b). The coal crops out along the margins of the Illinois Basin and Miles Herrin Coal Extent of Pennsylvanian System Figure 1 Extent of the Herrin Coal in the Illinois Basin. reaches a maximum depth in Illinois of about 1 ,300 feet (figs. 2 and 3). No resources of the Herrin Coal have been mapped in Indiana. Remaining identified resources of Herrin Coal in Illinois and Kentucky are approximately 82 billion tons, of which 96% (79 billion tons) is in Illinois (fig. 4, Kentucky tonnage from William Andrews, personal communication, 1999). This represents about 40% and 29% of all the identified coal resources in Illinois and the Illinois Basin, respectively. The Herrin Coal has been mined in Illinois for well over 100 years (fig. 5). Because of the vast resources of Herrin Coal, its production history reflects social and political events rather than the development and depletion cycle typical of non-renewable resources. From a beginning sometime in the 1800s produc- tion rose rapidly in the early 1900s with the discovery of thick deposits of Herrin Coal in southern Illinois. The all-time high production exceeded 60 million tons per year in 1918. Production declined after World War I and then dropped sharply during the depression to a low of 23 million tons. Production rose nearly to all-time highs again during World War II and fell back to the low 30 million tons after the war. Growing demand for electricity led to production growth again in the mid-1960s. Except for strike years, produc- tion hovered around 45 million tons per year until the early 1990s. Production has declined steadily since 1994 because of restrictions on the use of high-sulfur coal legislated by the Clean Air Act and competition from Powder River Basin coal. In 1999, twelve Illinois mines produced a total of 24 million tons from the Herrin Coal, approximately 60% of total state production (Illinois Office of Mines and Min- erals, personal communication). Thick resources of Herrin Coal in Illinois are found mostly in the southern half of the state; the largest area of thick coal is found in a wide arc stretching from just south of Springfield, through the southwest- ern part of the state, to Harrisburg (fig. 6). Smaller areas of thick coal are found in east-central Illinois in the vicinity of Danville and in central Illinois in the vicinity of Newton. Recent and historical mining of the coal has been concentrated around the margins of the coal field, particularly in southwestern Illinois and in shallow surface-minable deposits west of the Illinois River. The coal is thin or absent throughout much of the east-central and extreme northern portions of the coal field. Quality of Coal The Herrin Coal is a high-volatile, bituminous coal that ranges in rank from rank A in the southeastern corner of the state to rank C in the northwestern two-thirds of the state (fig. 7). Over the same area, heat content ranges from more than 25 million Btu per ton to less than 20 million Btu per ton (as received). Ash is commonly in the range of 9% to 12% (as received); slightly lower ash contents are reported in the southeastern part of the state. Well locations II II I I I I I -2,000 Figure 2 North-south cross section of the Pennsylvanian System in Illinois (modified from Treworgy et al. 1999a). Coal depth (feet) Less than 200 200 to 500 500 to 1 ,000 greater than 1 ,000 Mined-out areas; Herrin Coal Subcrop of the Herrin Coal k 50 Miles Figure 3 Depth of the Herrin Coal. 150 - ,o c o m 100 - Other seams Herrin Coal 50 - inois Indiana W. Kentucky Figure 4 Remaining coal resources in the Illinois Basin. The sulfur content of the Herrin Coal is closely related to the coal's depositional history (Gluskoter and Simon 1968, Treworgy and Jacobson 1986). In areas where the Herrin peat swamp was inundated with marine waters, the sulfur content of the coal is commonly in the range of 3% to 5% (as-received basis, equivalent to 2.5 pounds to 5 pounds of sulfur per million Btu, fig. 8). In these areas, the coal typically is overlain by a sequence of marine rocks including black shale and limestones. In areas where the peat was buried by a thick (>20 feet) layer of clastic sediments before or shortly after the swamp was inundated by ma- rine waters, the sulfur content of the coal is as low as about 0.5%. These lower sulfur areas are typically associated with the Walshville Channel, a river that was contemporaneous with the Herrin peat swamp. The clastic sediment that covered the peat, now lithified into a sequence of shale, siltstone, and sandstone, is called the Energy Shale. Chlorine content of the coal is loosely correlated to depth and increases from <0.1% (as received) at shallow depths along the margins of the basin to >0.6% in the central part of the basin (fig. 9, Chou 1991). Chlorine content in British coals has been correlated with corrosion and fouling of high-tempera- ture boilers, but no studies or field experiences have reported or confirmed such a correlation with respect to chlorine in coals from Illinois (Monroe and Clarkson 1994, Chou et al. 1998 and 1999). The quality of coal was not considered in determining availability. Although coal quality is an extremely important factor in individual sales contracts and the magnitude of demand for coal, the availability for mining of a specific deposit of Herrin Coal cannot be ruled out based strictly on quality. Because most Herrin Coal resources have a relatively high-sulfur content, demand for them is currently limited. How- ever, the market for high-sulfur coal, although reduced in size, is expected to continue and may even increase as power plants with new emission control technologies come on line. To identify what portion of the Herrin resources are available to meet that demand, available resources are classified by sulfur content. A logical continuation of this study would be to further characterize coal resources by other quality parameters important to the marketing of coal (e.g., ash, chlorine, trace elements). However, substantially more coal quality data are needed to make such a characterization feasible. Q l " ' ' "in in ii i in 1 1 i i inn ii hi 1 1 inn mi i ii OOOOOO OOOOOO) C35O' _ CMC0 , S" W CO t^- 00 CT> 05 Figure 5 Annual production of the Herrin Coal in Illinois. Coal thickness (inches) Less than 28 28 to 42 42 to 66 Greater than 66 Y / /\ Insufficient data ==§11= Coal split or thin Sandstone channel; no coal Mined-out areas; Herrin Coal Subcrop of the Herrin Coal A 50 Miles Figure 6 Thickness of the Herrin Coal. Quadrangle Studies The criteria defining available resources were developed through a series of 21 assessments of 7.5-minute quadrangles (fig. 10;Treworgy et al. 1994, 1995, 1996a,b, 1997a, 1998, 1999b; Jacobson et al. 1996; Treworgy 1999; Treworgy and North 1999). These assessments included interviews with more than 40 mining engineers, geologists, and other mining special- ists representing 17 mining companies, consulting firms, and government agencies actively involved in the Illinois coal indus- try. Additional background of this program and a detailed de- scription of the framework for the investigations in Illinois are provided in previous reports (e.g., Treworgy et al. 1994). Quadrangles were selected to cover the range of physiographic and geologic conditions associated with mining the Herrin Coal. Quadrangle selection was not random, but rather focused on resources that have the highest potential for development (e.g., thick or lower sulfur content seams). This approach was taken to ensure that the most economically important deposits re- ceived sufficient study and that little time was spent on coal that is unlikely to become available for mining in the foreseeable future. Maps at 1 :24,000 scale showing the major coal seams, related geology, mines, and land use in each quadrangle were com- piled based on previous regional investigations of mining condi- tions, resources, and geology. These maps provided the basis for detailed discussions with experts from mining companies, consulting firms, and government agencies active in the Illinois mining industry to identify the factors that affect the availability of coal in each quadrangle. Each quad- rangle was discussed with three or more experts to develop a set of criteria for defining available coal. These criteria were then applied to each quadrangle to calculate the available resources and to identify the factors that restrict significant quantities of resources from being minable. Of the 21 quadrangles studied, 17 included some resources of the Herrin Coal (fig. 10, table 2). The to- tal Herrin Coal resource in these 17 quadrangles was more than 4 billion tons, or about 4% of the origi- nal Herrin resources in the state. Availability of the coal in the 17 quadrangles ranged from none to 95% and averaged 45%. Figure 7 Rank and heat content of the Herrin Coal (modified from Treworgy et al. 1997b). Sources of Data and Limitations of Maps The maps used for this study were compiled from data obtained from a variety of public and private sources and have varying degrees of completeness and accuracy. The maps are designed for regional assessment and have a resolution of 1 :500,000 or better. Features or details of features smaller than about one-half mile across may not be accurately portrayed or may be omitted altogether. Resources of the Herrin Coal have been mapped by a number of previous studies. This assessment utilized the sources identified in appendix 1 . Resources were revised in eight counties utilizing data acquired since the previous investigation. Minor corrections and revisions were made in a number of other counties. Mined areas were updated to about January 1 , 2000, by using maps obtained from coal companies. Sulfur (pounds per million Btu) Less than 0.6 Tr °y Mining district 0.6 to 1.67 HUSH Walshville Channel; no coal 1.67 to 2.5 — — Transitional roof Greater than 2.5 Extent of the Herrin Coal A 50 Miles Figure 8 Sulfur content of the Herrin Coal. Chlorine (percent) Less than 0.1 0.1 to 0.2 0.2 to 0.3 0.3 to 0.4 Greater than 0.4 A ■ 50 Miles — \ Subcrop of the Herrin Coal Figure 9 Chlorine content of the Herrin Coal (modified from Chou 1991). 10 TECHNOLOGICAL AND LAND-USE FACTORS THAT AFFECT THE AVAILABILITY OF COAL FOR MINING Most technological or land-use factors that restrict mining are based on economic and social consider- ations and are not absolute restrictions on mining. Companies can choose to mine underground in areas of severe roof or floor conditions or thin seams if they are willing to bear the higher operating costs, interruptions and delays in production, and lower employee morale that result from operating in these conditions. It is possible to mine through most roads or under small towns if a company is willing to invest the time and expense necessary to gain approval from the appropriate governing units or indi- vidual landowners and to mitigate any damage. Previous economic and social conditions have, at times, enabled companies to mine in areas where factors are now restrictive. The current highly competitive price environment in the coal industry, which makes coal that is more expensive to mine uneconomic, is expected to prevail in the Illinois Basin indefinitely. Therefore, the criteria used to determine available coal for this report are likely to cover mining conditions for the foreseeable future. The criteria used in this study to define available Herrin Coal are a composite set of rules based on our interviews with mining companies, observations of mining practice, and the assessments of the 21 quadrangles. Additional information can be found in the study reports on individual quadrangles where these conditions were encountered. In some cases it was necessary to modify or omit certain criteria used in the quadrangle studies to take advantage of existing statewide data or because the criteria were too complicated, costly, or impractical to apply in a statewide assessment. Modifications and omissions of criteria are noted in tables 3a and 3b and explained in the following sections. These changes had minimal effect on the overall results of the statewide assessment. Some factors were modified during the course of the quadrangle studies as additional information was collected. For example, a different minimum block size for surface mining was used in several studies. The minimum was set at 15 million tons-in-place in the initial study. This minimum was based on the conditions in the Middletown Quadrangle and the practices of the companies interviewed (Treworgy et al. 1994). As additional quadrangles were studied and companies interviewed, the minimum size was changed to 10 million tons of clean coal and then modified further to as little as 150 thousand clean tons per mine pit with a cumulative pit total of 10 million tons of clean coal. Table 2 Resour ces of the Herrin Coal in individual quadrangles studied (millions of tons). Available with Original Mined Remaining Available potential restrictions Restrictions Quadrangles Technological Land use Albion South 287 287(100) 1 68 (24) 5 (2) 208 (72) 6 (2) Atwater 301 301 (100) 231 (77) 65 (22) 5 (2) Collinsville 436 196(45) 241 (55) (0) 135(31) 10 (2) 95 (22) Galatia 330 19 (6) 311 (94) 232(71) 61 (19) 18 (5) Kewanee South 76 8(10) 68 (90) 40 (53) 5 (7) 23(31) Mascoutah 462 60(13) 402 (87) 182(39) 177 (38) 43 (9) Middletown 47 47 (100) (0) 47 (100) <1(<1) Mt. Carmel 229 229(100) (0) 209 (91) 20 (9) Newton 380 380(100) 359 (95) (0) 20 (5) Nokomis 413 110(27) 303 (73) 183(44) 89 (22) 47 (37) Peoria West 127 2 (1) 126 (99) 3 (2) 55 (43) 21 (17) 47(37) Pinckneyville 380 107(28) 273 (72) 233(61) 12 (3) 27 (7) Princeville 112 2 (1) 110 (99) 30 (27) 59 (53) 22 (20) Shawneetown 82 5 (6) 77 (94) 7 (8) 64 (78) 7 (8) Springerton 302 302(100) 257 (85) 27 (9) 12 (4) 5 (2) Tallula 46 46(100) (0) 12(26) 24 (52) 10(22) Villa Grove 86 86(100) 6 (7) 13(15) 63 (73) 5 (5) All combined 4,097 507(12) 3,589 (88) 1 ,830 (45) 147 (6) 1,127 ' (28) 385 (9) 'Numbers in parentheses are percent of original resources. 11 Snyder/ est Union 50 Miles Coal thickness (inches) Less than 28 28 to 42 42 to 66 Greater than 66 Vincennes . Carmel South / / r Insufficient data ===== Coal split or thin IHI I I I l lll Sandstone channel; no coal Extent of Pennsylvanian strata County boundary Study areas with Herrin resources [\] Other study areas Shawneetown Figure 10 Quadrangle study areas used to identify criteria for coal available for mining. 12 Most factors used in this assessment could apply to any coal seam in Illinois. However, the specifics of certain criteria vary from seam to seam. For example, the minimum thickness of bedrock for under- ground mining of the Springfield Coal differs from that of the Herrin Coal because of the different com- petencies and lithologies of rock units overlying the two seams. The restrictions are organized according to the relevant mining methods (surface or underground min- ing) as currently practiced in Illinois. Because surface mining can be used to mine coal lying as deep as 200 feet and underground mining can be used to extract coal lying as shallow as about 40 feet (if there is sufficient bedrock), resources that are 40 to 200 feet deep were evaluated for their availability for both surface and underground mining. This study does not consider the availability of coal that could be mined using an auger or highwall miner. These techniques, which allow additional tonnages of coal to be recovered from the final cut of a Table 3a Criteria used to define the Herrin Coal available for surface mining in this study and previous quadrangle studies. Surface mining Statewide study Quadrangle studies Technological restrictions Minimum seam thickness Maximum depth Maximum unconsolidated overburden Stripping ratio 2 Maximum Maximum average Minimum size of mine reserve (clean coal) Cumulative tonnage needed to support a mine and preparation plant Individual block size (thousands of tons) Less than 50 feet of overburden 3 More than 50 feet of overburden 3 Land-use restrictions (width of unminable coal around feature) Cemeteries State parks and preserves Railroads Federal and state highways Other paved roads (Peoria West only) Major airports High voltage transmission towers Pipelines Underground mines Subdivisions Towns Available with potential restrictions Only if surface mined in combination with overlying or underlying seam Potential land-use conflicts All otherwise available surface minable coal in areas where land-use patterns are incompatible with mining 18 inches 12 inches 200 feet 200 feet 60 feet various 1 25:1 25:1 20:1 20:1 10 million tons various 150 various 500 various not used 100 feet 100 feet 100 feet 100 feet 100 feet 100 feet 100 feet not used 100 feet 100 feet 100 feet not used 100 feet 100 feet 100 feet 200 feet 200 feet not used 500 feet 0.5 miles 0.5 miles not identified identified identified identified 'Quadrangle studies used a sliding scale based on depth of coal. 2 Cubic yards of overburden/ton of raw coal; volumes and weight not adjusted for swell factors or cleaning losses. 3 Quadrangle studies used categories of less than 40 feet and more than 40 feet of overburden. 13 Table 3b Criteria used to define the Herrin Coal available for underground mining in this study and previous quadrangle studies. Underground mining Statewide study Quadrangle studies Technological restrictions Minimum seam thickness Minimum bedrock cover Minimum ratio of bedrock to unconsolidated overburden Floodplains 1 Minimum interburden between minable seams Minimum size of mining block (clean coal) Faults (width of zone of no mining) Cottage Grove Fault System Master fault Subsidiary faults Rend Lake Fault System Centralia Fault Wabash Valley Fault System Walshville Channel: no mining within Anvil Rock Channel: no mining within Energy Shale: no mining within Anvil Rock Sandstone within 5 feet of coal Partings: Minimum yield Maximum thickness 2 Land-use restrictions (width of unminable coal around feature) Surface and underground mines Towns Subdivisions Churches and schools Cemeteries High-voltage transmission towers Interstate highways Major airports Dams Closely spaced oil wells Available with potential restrictions Closely spaced oil wells Potential land-use conflicts All otherwise available underground minable coal with areas where land- use patterns are incompatible with mining Coal quality limitations Bedrock cover 42 inches variable 1:1 40 feet 40 million tons 42 inches 40 feet not used 40 feet 20 to 40 million tons 500 to 1 000 feet variable 100 feet none 200 feet 300 feet 800 feet 1 ,000 feet 0.5 miles 0.5 miles 1 ,800 feet 1 ,800 feet transition zone transition zone identified identified not used 65% clean coal 200 feet 200 feet Ofeet various not used various not used 100 feet not used 100 feet not used 100 feet 100 feet 100 feet 1 00 feet 100 feet 100 feet 100 feet >7 wells per not used 40 acres 4-7 wells per >4 wells 40 acres per 20 acres identified identified none resources with chlorine contents >0.4% >minimum not used but < 100 feet 'In the quadrangle studies, the tonnage of available coal within floodplains was reduced by 20%. In this state- wide assessment, floodplains are considered a restriction only if bedrock is less than 100 feet thick. 2 Areas where partings are likely to be too thick for mining were identified. Data were generally insufficient to isopach parting thickness. 14 surface mine, have been used on a limited basis in Illinois. In many cases this coal will be minable by underground methods. Most of the factors that restrict underground mining, with the exception of seam thickness, will also restrict auger or highwall mining. The amount of additional tonnage that is recover- able by these methods is probably not significant. Surface-Minable Coal Depth of Seam Although open-pit mining methods can remove hundreds of feet of overburden, sur- face mining of coal as practiced in Illinois currently has an economic limit of about 200 feet or less. De- pending on their thickness, coals less than 200 feet deep can be mined by either surface methods or underground methods (provided there is sufficient bedrock cover). The selection of surface or under- ground methods depends on the comparative cost of extraction and the overall character of a company's reserves at a specific site. For example, if a company's reserve block is primarily deeper than 150 feet, or if the company does not own the rights to the land surface, it may elect to mine all of the coal by underground methods. Coals may be unavailable for surface mining because of their strip- ping ratio, a function of depth and thickness. Stripping ratio is discussed separately. Thickness of Seam For this statewide assessment, the minimum thickness of coal for surface mining is 1 8 inches. In the quadrangle studies, a minimum thickness of 1 2 inches was used for the lowermost seam in an interval to be mined and 6 inches for overlying seams within the interval. Seams thinner than 18 inches have been mined in Illinois in small areas under certain conditions. No extensive areas of Herrin Coal less than 18 inches thick have ever been mined in the state, and existing resource maps do not include any coal thinner than 18 inches. Thinner seams are more costly to recover because the amount of out-of-seam dilution is a greater percentage of the material handled. Resources less than 18 inches thick could not be mapped within the time and budget constraints of this project, but the amount of unmapped resources is likely insignificant. Stripping Ratio Stripping ratio is the number of cubic yards of overburden that must be removed to recover each ton of coal. Whereas the thickness and depth of coal that can be economically mined are controlled in part by technical factors such as mining equipment, the maximum stripping ratio is strictly an economic limit. Coals with high stripping ratios may be more economical to mine by underground methods or may remain unmined until the market price for coal increases relative to production costs. Companies calculate stripping ratios on the basis of the anticipated tonnage of clean coal that will be produced. This calculation requires assumptions about the type and performance of mining and wash- ing equipment to be used, as well as tests of the washability of the coal. For this study, the stripping ra- tios were calculated with the tonnage of in-place coal, excluding partings. In-place tonnage is 5% to 15% higher than the actual tonnage of clean coal after mining and cleaning losses. Some companies use a "swell factor" to account for the increase in volume of overburden after it is blasted. Swell factors for lithologies typically encountered in Illinois mines range from 1 (no swell) for sand to 1 .7 for shale (Allsman and Yopes 1 973). Use of swell factors requires detailed site-specific knowledge about the quantities of different lithologies in the overburden (e.g., shale, limestone, sand, and clay), and we did not use them in our calculations. Cubic yards of overburden were calculated sim- ply from the total thickness of consolidated and unconsolidated material overlying the coal. For this study, the maximum stripping ratio adopted for available coal was 25 cubic yards of overburden per ton of in-place coal (25:1). The maximum average stripping ratio for any mining block was 20:1. As- suming a 1 0% loss of coal in mining and cleaning and an average overburden swell factor of 1 .3, these ratios are equivalent to 36:1 and 29:1 , respectively. These ratios are slightly higher than the limits cur- rently used by companies actively involved in surface mining in Illinois. High stripping ratios are a factor mostly in the northern half of the state (fig. 11). Because the coal is relatively thick in the southern half of the state, overall depth, rather than stripping ratio, is a limiting factor. Thickness of Bedrock and Unconsolidated Overburden Thick deposits of glacial drift or alluvial sediment can restrict surface mining because of their potential to slump into the pit, fail under the weight of large draglines, and allow excessive groundwater flow into the pit (fig. 1 2). A minimum amount of bedrock overburden is needed to ensure that the coal is not weathered and to provide stable material to hold the toe of the spoil pile. The maximum thickness of unconsolidated material that can be handled is 15 A. Southwestern Illinois Stripping ratio Insufficient data for coal thickness H Less than 25:1 ^^ C oal deeper than 200 feet More than 25:1 ^^_ Surface-mined areas; Herrin Coal ^ Subcrop of the Herrin Coal Figure 11 Stripping ratio of the Herrin Coal. A 50 Miles 16 dependent on the lithology of the overburden, its physical properties (e.g., load-bearing capacity, per- meability), and the presence or absence of groundwater. The minimum bedrock and maximum glacial drift thicknesses that were handled by the companies we interviewed also depended on the mining plan and the type of equipment they were using to remove overburden. We did not compile sufficient information to assess the lithology and physical properties of the uncon- solidated sediments in the quadrangles studied. The experience of the companies suggests that for an overburden thickness of 50 feet or less, a minimum of 10 feet of bedrock cover is needed. For over- burden between 50 feet and 100 feet thick, one-third to one-half the material should be bedrock. The maximum thickness of unconsolidated overburden that can be handled over a large mining area is approximately 60 feet. Small areas of thicker unconsolidated overburden can be mined, but large areas of thick unconsolidated overburden generally will be avoided. Because of the resolution of the bedrock cover and drift thickness maps used in this study, the only cri- terion we used for surface mining was a maximum of 60 feet of unconsolidated overburden. Thick, un- consolidated sediments limit surface mining in much of the state except for the southwestern and southern areas of the coal field (fig. 13). Size and Configuration of Mining Block A mine reserve must contain sufficient tonnage to allow a company to recover the costs of developing a mine (e.g., exploratory drilling, land acquisition, equip- ment purchase, and construction of surface facilities and initial box cuts or shafts). Because of their lower development costs, greater equipment mobility, and flexibility in operating plans, surface mines can be developed with smaller reserves and mining blocks than can underground mines. Small surface mines can be developed using trucks and earth-moving equipment that can be readily transported to the site. Most Illinois coals are cleaned to some degree before final shipment. The coal can be trucked from the mine pit over the existing road network to a central preparation plant. Companies currently consider the minimum recoverable tonnage for a surface mine to be 1 million saleable tons. For this study we as- sumed an 85% recovery rate, which makes the minimum tonnage equivalent to about 12 million tons of raw coal in place. The tonnage may be distributed among a number of adjacent blocks. Each mining block should contain at least 150 thousand tons of saleable coal (approximately 175 thousand tons of raw coal) if the coal is less than 50 feet deep or 500 thousand tons (590 thousand tons of raw coal) if the coal is greater than 50 feet deep. For a 48-inch thick coal, these minimum blocks would be about 25 acres and 80 acres, respectively. A. Slumping of mine highwall B. Water-bearing zones C. Roof falls D. Floor squeezes Coal seam XXXXXXX X X XX Figure 12 Problems encountered in surface and underground mines that have overburden consisting of thick unconsolidated sediments over thin bedrock (modified from Treworgy et al. 1998). 17 A. Southwestern Illinois Unconsolidated overburden thickness (feet) Less than 60 Greater than 60 Surface-mined areas; Herrin Coal Subcrop of the Herrin Coal A 50 Miles Figure 13 Thickness of unconsolidated overburden in counties with surface-minable resources of the Herrin Coal. 18 In this study, very few mining blocks were eliminated because they did not have the minimum tonnage to support surface mining. More commonly, blocks were considered unavailable because their geometry was unsuitable for mining. For example, narrow strips of land between roads and railroads; narrow, sinuous stream valleys; and irregularly shaped areas between abandoned mines are commonly unsuit- able for mining. Land Use Although almost any land use or surface feature can be undermined or mined through if a company obtains permission from the owner and agrees to repair damages, companies generally find it impractical to mine under or through certain features because of the expense of restoring the feature or the social and political hurdles required to obtain the necessary permission. A buffer of unmined coal must be left around any property or surface feature that the company does not own and is not permitted to disturb. State law requires that surface mines leave a 300-foot buffer around churches, schools, and other occupied dwellings. In practice, mining companies may purchase a few individual structures if do- ing so frees up a sufficient tonnage of resources for mining. A large buffer, although not required by law, is commonly left around towns because of the potential for disturbance by dust, vibrations from blasting, and disruption of water wells. Our quadrangle studies considered all coal under towns, rural subdivisions, railroads, airports, high- voltage transmission towers, schools, churches, and cemeteries as unavailable for surface mining. For this statewide assessment, it was impractical to map small features such as transmission towers, rural subdivisions, schools, churches, and cemeteries. Since these features typically affected less than 1% of the resources in the quadrangles studied, their omission should not materially affect the results of this statewide assessment. In this assessment, we considered coal within a half mile of towns (as defined by their municipal boundaries) to be restricted from surface mining (fig. 14). Roads can be a significant barrier to surface mining. Because of local opposition to mining and the rela- tively small value of the coal beneath roads (because of seam thickness), most paved roads in the western and northwestern parts of the state are considered a restriction to surface mining. In southern Illinois, the general acceptance of surface mining by the local population and the higher tonnage of coal per acre make it feasible for companies to surface mine through lightly used roads. For this statewide assessment, we considered state and federal highways to be restrictions to surface mining (fig. 15). An additional 1% to 2% of resources is probably restricted by other paved roads in the western part of the state. Other land-use features that restrict surface mining are railroads, pipelines, and public lands (figs. 16, 17, and 18). Although there have been situations where mining companies have arranged to move or mine through these features, commonly they are left unmined. Abandoned Mine Workings Illinois law requires that surface mines have an unmined barrier of coal 500 feet wide around active or abandoned underground mine workings. This requirement may be waived under certain conditions, and surface mines have in many instances mined through all or portions of small abandoned underground mines. This may be done because the extent of the underground work- ings is not known or the area of the underground workings is so small that it is not worth the expense of diverting the surface operation around it. In most cases, these mines are less than about 4 acres in size. Larger underground mines are avoided by surface mining because the amount of recoverable coal is significantly reduced and there is a potential for large quantities of water to be present in the abandoned mine. Although in our quadrangle studies we assumed that surface mines would obtain waivers to mine through small abandoned underground mines, it was not practical to differentiate between small and large underground mines in this study. Instead, for this statewide assessment, we assumed that surface mines would be permitted to mine through any mine in an overlying seam and to mine within 200 feet of underground mines. Surface Mining of Multiple Seams In a number of our quadrangle assessments we found that addi- tional Herrin Coal was available for surface mining if mined in combination with the overlying Danville Coal or underlying Springfield Coal. In these cases, the additional tonnage of the underlying or overlying coals reduces the overall stripping ratio to less than 25:1 . Opportunities for multiseam mining were not evaluated in this statewide assessment of the Herrin Coal. Multiseam mining probably could increase the tonnage of available coal in parts of northwestern Illinois by a few percent, but the potential for multiseam surface mining in west-central and southwestern Illinois is 19 -f-«!T s J Major fault systems N! ^>^ Minor faults and igneous dikes "** — ^ Subcrop of the Herrin Coal A 25 Miles Figure 29 Areas of the Herrin Coal affected by faults and igneous dikes. 33 tonnage of material mined is considered by most companies to be the minimum necessary for an operation to be eco- nomic. Mining only the lower or upper bench of coal may be a solution, but mining conditions can be difficult. Nelson (1983) offered two detailed case studies of mining in areas of extensive partings. Because areas of extensive partings have highly variable coal thickness and require numerous, closely spaced data points to accurately map resources, past ISGS studies have not mapped coal thick- ness or calculated resources in these areas but have simply mapped them as areas of "split coal." For this statewide assess- ment, we also assumed that these areas would be unminable and made no attempt to calcu- late the tonnage of affected coal in the previously identified areas. A few additional areas where numerous, thick partings are present were identified in this study. The total tonnage of resources in the areas of partings is estimated to be about 1 billion tons. Figure 30 Shale partings in the Herrin Coal near the Walshville Channel, Old Ben No. 11 Mine, Franklin County (Coal Section files, ISGS). Walshville Channel and Energy Shale The Walshville Channel, a drainageway through and contem- poraneous with the peat swamp of the Herrin Coal, has strongly influenced the thickness, quality, and minability of the Herrin Coal (figs. 8 and 33). The coal is generally thick (7 feet to more than 14 feet) in a zone along and extending from one to several miles away from this channel. Immediately adjacent to the channel, the coal is commonly split into two or more benches separated by shale, siltstone, and sandstone a few inches to tens of feet thick. Within the course of the channel, the coal is missing and is replaced by sandstone, siltstone, and shale. Asso- ciated with the channel is the Energy Shale Mem- ber. This unit is light to dark gray shales, siltstones, and sandstones deposited directly on top of the Herrin Coal along a wide zone along the Walshville Channel. The unit is more than 1 00 feet thick adja- cent to the channel and thins and pinches out from the channel for several hundred feet to several miles. Although locally the Energy Shale and underlying coal may be disturbed by structural or deformational „_ _ . „ features such as rolls and low-angle shear zones, Figure 31 Rib rashing in the Herrin Coal; note the po- ... . . . . . „ , „i„^„ ■* ,,u 1,1 u .1 this unit common y makes a stable roof unless sition of the blue band. y 34 exposed to moist, humid air (Krausse etal. 1979, Nelson 1983). Two known exceptions to this stable roof are cer- tain planar-bedded facies and the margins of the unit where the thick- ness of the Energy Shale changes abruptly over a short distance. A finely laminated or planar-bedded shale, siltstone, and sandstone facies of the Energy Shale make an un- stable mine roof (Krausse et al. 1 979, Breyer 1 992; figs. 34 and 35). The rock easily splits along these part- ings, and extensive roof control mea- sures are required. In addition, the sandstone and siltstone facies may contain water, which also contributes to weakening of the roof strata and the degradation of mining conditions. The distribution and extent of these facies are not known, and data are in- sufficient to map them for this study. 10 Nokomis Coal Co. no. 1 (Kay 1922) Christian Co. no. 857 Christian Co. no. 2196 Montgomery Co. no. 741 coal coal coal limestone black shale blue band coal coal shale coal coal shale shale coal coal coal coal shale shale Floor of Herrin Coal Figure 32 Examples of partings in the Herrin Coal in the Nokomis Quadrangle (Treworgy et al. 1996b). The margins of Energy Shale deposits, characterized by areas of abrupt thin- ning (e.g., thinning 60 feet to 80 feet over less than 0.5 miles), have been correlated with severe roof conditions in mines. It is not known whether the weakness of the roof in these areas is due to the effects of differential compaction of sediments, a change in facies, ancient slumps of the unlithified sediments, or a combination of these and other factors (fig. 36). Because of the severity of the roof falls experienced in these areas, companies commonly avoid mining in the vicinity of the deposit margins (fig. 37). Mines that attempt to mine coal under both the Energy Shale and adjacent deposits have found it necessary to minimize the amount of mining in this transition zone. The exact boundaries of this zone are not known. *r 1 In tn ^ SOO frrt »» -tf" 1 In tn R milr^ — > _____ W"^t~-~^^ -^ Energy Shale Bankston Fork Limestone <^A // G Walshville E_^— _^^S!pf^rt ^ JL E~^^ A_^ l^^& C"— ~ F ____ft XXX X X x x X Herrin Coal <^H ___^T <^^"T x - X X^^W 1 ■ *" Channel 30-, A. Normal roof; marine strata feet B. Pod of Energy Shale C. Low-angle slips and disturbed roof 200 feet D. Transition zone E. Rolls and laminated facies F. Irregular seam topography G. Partings Figure 33 Areas of adverse mining conditions in the Herrin Coal near the Walshville Channel. 35 Figure 35 Large roof fall in laminated Energy Shale, Jefferson County (Coal Section files, ISGS). Figure 34 Core of the laminated siltstone and shale facies of the Energy Shale, Doug- las County (Coal Section files, ISGS). For purposes of estimating the amount of coal that may be restricted by these severe roof con- ditions, this study defined the transition zone as a belt 1 ,500 feet wide that roughly corresponds to the area where the Energy Shale thickens abruptly from 5 to 30 feet. In practice, mining companies may find this zone to be wider or narrower, depending on local conditions as well as variables associ- ated with mine design (e.g., roof bolting plan, size of rooms). Other problems that create poor mining conditions near the Walshville Channel include abrupt variations in the thickness of coal or partings, steep changes in the elevation of the coal, and local washouts of the seam. These conditions are difficult to predict and delineate, even with data from closely spaced drill holes. Mines are commonly laid out so that areas of potential problems can be probed and mining plans abandoned if conditions are found to be unfavorable. In some areas, severe problems have been en- countered as much as several miles from the channel (Nelson 1983). Because drill holes spaced only a few hundred feet apart are needed to identify many of the undesirable geologic features associated with the Walshville Channel and the Energy Shale, these features could not be specifically delineated in this study. To estimate the amount of coal that may be unminable be- cause of conditions related to the Walshville Channel, this study considered coal less than a half mile from the channel to be unavailable for mining (fig. 38). In some areas, this coal may ultimately be found to be minable, but in other areas, coal farther from the channel will likely be declared unminable. Anvil Rock Channel and Sandstone Overlying Coal The Anvil Rock Sandstone Member consists of various related facies of elastics deposited some time after the Herrin peat swamp had drowned and been buried by several cyclic sequences of shale and limestone (Hopkins 1958). During the period of Anvil Rock deposition, a river or rivers eroded sediments down to and through the Herrin Coal across wide areas of southern Illinois (fig. 38). In addition to partially or totally removing the coal in some areas, the Anvil Rock Sandstone creates severe roof problems where it is within 5 feet of the top of the coal bed (Treworgy et al. 1 998). In these areas, the Brereton Limestone, the preferred target for anchoring 36 Figure 36 Extensive roof bolting used to hold Energy Shale roof in an area disrupted by slump-like features (see C, fig. 33). roof bolts, may be missing. The rock between the coal and the sandstone is commonly weak, particu- larly if the normal rock sequence has been removed by channel scour. In addition, holes drilled into the sandstone for roof bolting allow water to enter the mine, especially if the water is under artesian pres- sure, as it is in some areas. Areas of Herrin Coal in southern Illinois restricted from mining by the Anvil Rock Sandstone were identi- fied for this study by creating an 1 , 800-foot buffer zone along the main Anvil Rock Channel and map- ping additional areas away from the channel where the sandstone was within 5 feet of the coal seam. Our experience and knowledge of the mines near the Anvil Rock Channel indi- cated the zone where the coal is closely overlain by sandstone and where roof problems may be encountered. This zone extends approximately 1 ,800 feet from the edge of the main area of eroded coal. Too few drilling data are available to map this zone along the en- tire length of the channel. Examination of drill logs along the channel in areas where sufficient data were available con- firmed that, although this zone is wider in some areas and narrower in others, 1 ,800 feet is a reasonable figure to use for estimating the amount of restricted coal (fig. 39). Additional areas where the sandstone was within 5 feet of the top of the Herrin were mapped using drilling records in the public files of the ISGS. These areas were found to roughly cor- responded with the areas of thick sand- stone mapped by Hopkins (1 958). Figure 37 Patterns of underground mining and type of roof strata, west-central Illinois. 37 1111111 Walshville Channel; coal eroded W%%%. Anvil Rock Channel; coal eroded HHH Sandstone within 5 feet of coal HHI Mined-out areas; Herrin Coal Extent of the Herrin Coal A 50 Miles Figure 38 Areas of the Herrin Coal with Anvil Rock Sandstone within 5 feet of the roof. 38 <-0.5-2 miles- several miles Danville Coal -1 ,800 feet — >K-0.5-2 miles-^ Figure 39 Schematic cross section showing the relationship of the Anvil Rock Sandstone to other strati- graphic units. Potter and Simon (1961) mapped what was thought to be the Anvil Rock in west-central Illinois. The major sandstone body mapped by Potter and Simon has since been determined to be an older sand- stone filling the Walshville Channel. Minor bodies of Anvil Rock Sandstone are present west of Taylorville and south of Hillsboro. Although the sandstone in these areas has caused local mining problems, the tonnage of resources affected is not significant (DeMaris and Nelson 1 990, Nelson 1 983). Broad areas where the sandstone is within 5 feet of the top of the coal are not known to be present, and the coal is minable up to these minor channels. Size and Configuration of Mining Block In the quadrangle assessments, the minimum block sizes for underground mining ranged from 40 to 100 million tons in place, depending on the depth of the resources. Mines at a shallow depth (e.g., less than -250 feet) can be opened from a highwall, box cut, or shallow slope; exploratory drilling will be relatively inexpensive. Deeper mines require higher initial exploration and development costs, so a larger block of coal is needed to recover those investments. Mine blocks must also have dimensions that are suitable for the mine layout. Narrow blocks of coal with convoluted shapes (such as between abandoned mines or other barriers) cannot be safely or economi- cally mined by underground mining methods. In this statewide assessment, we used a single minimum block size of 80 million tons in place. This sim- plification did not have a material effect on the tonnage of coal eliminated because of block size. Only about 400 million tons of coal less than 250 feet deep were in blocks less than 80 million tons in size, and most of this coal lay between mined areas in narrow blocks that had configurations unsuitable for the layout of a mine. Land Use The quadrangle studies identified ten land uses that restrict underground mining: towns, rural subdivisions, interstate highways, schools, churches, cemeteries, high-voltage transmission lines, public lands, airports, and dams. Limited extraction may take place under many of these features if per- mission is obtained, including under small towns with populations of a few hundred. However, unless such an area is crucial to development of the mine layout, it will generally be avoided. Because of the expense of mapping features relative to the amount of coal restricted, this statewide assessment delin- eated only towns, interstate highways, public lands, and large airports and dams. Some of the compa- nies that we interviewed do not mine under railroads. However, in recent years, at least two longwall mines in Illinois, the Monterey No. 1 Mine and the Orient No. 6 Mine, have extracted coal underlying railroads. This study, therefore, considers coal underlying railroads to be available for underground mining. 39 A buffer of unmined coal must be left around any property or surface feature that cannot be disturbed. The size of the buffer depends on the depth and thickness of the coal, the composition of the overbur- den, and the angle of draw used to calculate the area that could be affected by subsidence from under- ground mining. Although the individual quadrangle studies used buffer sizes ranging from 100 to 400 feet, depending on the depth of the coal, this statewide assessment used a single buffer size of 100 feet or all features except towns. Towns were not buffered at all because the municipal boundaries of the majority of towns in the southern two-thirds of the state commonly extend past the area of actual sur- face development. In this study, the variation between the tonnage in areas measured as restricted by land use and that which might be obtained by more thorough mapping of features is not significant. Abandoned Mine Workings Illinois law requires that underground mines leave an unmined barrier of coal 200 feet wide around abandoned underground mine workings. A larger barrier may be required if the extent of the mine workings is not accurately known. Closely Spaced Oil Wells A block of unmined coal must be left around oil wells unless they are abandoned and known to be plugged to standards set by the U.S. Department of Labor's Mine Safety and Health Administration. Numerous, closely spaced oil wells (e.g., one well every 20 acres or less), whether active or abandoned, can restrict the availability of coal for mining, either by limiting access to the coal or raising the cost of mining. Unless closely spaced wells are plugged, they limit the develop- ment of entries and panels and prohibit longwall mining. Prior to the late 1940s there were no controls on the spacing of oil wells in Illinois. Some oil fields developed during this period have wells on spacings of 5 acres or less (fig. 40). In addition, these old wells may be poorly located and improperly plugged. Wells drilled since the late 1940s have been on spacings of one well per 10 or 20 acres. There are no regulations or clear-cut formulas for determining what number or spacing of wells consti- tutes a restriction to mining, nor can the area of coal restricted by wells be precisely defined prior to the development of a mine plan. If a well is abandoned, the mining company has only the expense of plug- ging the well (which is significant). If a well is active, the company must negotiate its purchase or design the mine layout to leave a pillar of coal around the well (fig. 41 ). The benefits of plugging a well are measured on a well-by-well basis and determined by the value of the coal that can be recovered and by the efficiencies that may be achieved in the mine layout. Areas of coal on the edge of a mine property may be left unmined if they contain numerous wells, but wells in strategic areas needed for main entries or development of longwall panels may be worth plugging. Figure 40 Closely spaced oil wells, Salem Oil Field, Marion County (ca. 1943, ISGS files). 40 For this study we examined mining patterns of current or recent mines operating in areas with many oil wells. Based on this examination, two categories of resources in areas of closely spaced oil wells were delineated (fig. 42). Resources in areas with four to seven wells per 40 acres are considered to be available with potential restrictions because the cost of mining these deposits will be higher than areas with few oil wells. Room and pillar mining can be conducted in these areas, but mining costs will be higher than areas without oil pools because of the need to buy and/or plug selected wells, tailor mining layouts to fit between wells, and extract a lower percentage of coal per acre. Resources in areas with eight or more wells per 40 acres are considered unminable. In addition to the high cost of plugging this many wells in an area, it may be difficult to locate all the wells. These increased costs and safety issues make it unlikely that mining will be attempted in these areas in the foreseeable future. Potential Land-Use Conflicts This category is used to represent "available" resources that, although lacking any specific land-use or technological restrictions, are in areas that are relatively densely popu- lated and experiencing ongoing suburban development. In addition, land values in these areas are probably unfavorably high for mining, and both surface and underground mines are likely to be viewed by the local population and government as incompatible with community development. The potential for community opposition to and interference with mining activities, as well as the long-term liability for sub- sidence damage from underground mining, are significant deterrents to mining. All of the mining experts we interviewed said that they would not risk their company's financial resources by attempting to put to- gether a mining block and developing a mine in such areas. Potential land-use conflicts involving the Herrin Coal occur east of Saint Louis, especially the communities of Belleville, Collinsville, and Edwardsville; in the vicinity of Peoria, East Peoria, and Pekin; and around La Salle. Intermixed with this development are fingers of resources that meet our criteria for available coal but are unlikely to be mined because of the surrounding development. AVAILABLE RESOURCES Statewide, about 51 billion tons (58%) of the original 89 billion tons of Herrin Coal resources are avail- able for mining (fig. 43, table 1 ). Of these available resources, 21 billion tons are 42 to 66 inches thick and 30 billion tons are greater than 66 inches thick (table 6, fig. 44). An additional 3 billion tons are available with potential restrictions because they are located in areas where geologic or land-use conditions may increase the cost of mining. These areas include those that have a medium density of oil wells or 75 to 1 00 feet of bedrock overburden or are near rapidly developing urban areas. Techno- logical factors restrict mining of 24% of the re- sources (21 billion tons), and land use restricts 4% (4 billion tons). Only 3 billion tons of the available resources have a medium- to low-sulfur content (<1 .67 pounds of sulfur per million Btu). These lower sulfur resources are available primarily by underground mining. Examination of these medium-and low-sulfur resources by mining district shows that almost all of the resources in the Quality Circle district have been mined out (table 7). The largest remaining available resources of medium- to low- sulfur coal are in the Charleston district. Significant quantities of available lower sulfur resources are potentially restricted by land use in the Troy (St. Louis metropolitan area) and Quality Circle (Rend Lake) districts. About 68% (54 billion tons) of the remaining resources of Herrin Coal are in the measured and indicated categories of reliability (see section £ a/ 1 ,000 y feet V \\ * ^^\ # • y \ unmined • \yN 9 / V? ^> ? >W /V^J-oil wells > ?> %*i Figure 41 Underground mine workings in an area of closely spaced oil wells. Wells within mined area were plugged and mined through. 41 Oil wells (number per 40 acres) 4 to 7 Greater than 7 A 50 Miles Extent of the Herrin Coal Figure 42 Areas of the Herrin Coal containing closely spaced oil wells. 42 on the coal resource classification system), and 74% (38 billion tons) of these are available for mining (table 8, fig. 45). A slightly lower percentage (53%) of the inferred resources are available compared with the measured and indicated resources, a reflection of the greater density of drilling carried out in the most attractive areas for mining. Land use restricts a lower percentage of the inferred resources than measured and indicated, probably because the inferred resources are largely away from towns, the historical centers of mining. Although the availability of some resources will be reclassified as a result of additional drilling, no major changes in the total tonnages are anticipated. Mined or lost 9.4 bt 11% Land use restriction 3.8 bt 4% Available with potential restrictions 3.1 bt 3% Coal Available for Underground Mining About 86 billion tons of the original Herrin Coal re- sources lie at depths greater then 40 feet and are therefore potentially minable by underground methods. Of these, about 57% (49 billion tons) is available for mining, and an additional 4% (3 billion tons) is available with potential restrictions (table 9, fig. 46). Tech nological factors restrict mining of 25% of the resources, and land use restricts about 5%. The major technological restrictions are thin bedrock and/or thick drift cover (9% of original resources), coal less Figure 43 Availability of the Herrin Coal for mining in Illinois (bt = billion tons). Table 6 Availability of the Herrin Coal by thickness category (billions of tons). 18-28 inches 28-42 inches 42-66 inches >66 inches Total Original 0.8 10.9 30.8 46.0 88.5 Mined <0.1 <0.1 (<1) 0.6 (2) 8.8 (19) 9.4(11) Remaining 0.8(1 00) 1 10.9 (100) 30.2 (98) 37.4 (81) 79.0 (89) Available <0.1 (1) 0.1 (1) 21.3 (69) 29.6 (64) 51.0(58) Available with potential restrictions <0.1 (<1) 1.5 (5) 1.6 (3) 3.1 (3) Technological restrictions 0.7 (89) 10.3 (94) 6.2 (20) 4.0 (9) 21.1 (24) Land-use restrictions <0.1 (10) 0.5 (5) 1.2 (4) 2.1 (5) 3.8 (4) 'Numbers in parentheses are percent of original resources. -□ ,§ 251 "' c/> 20 - c o m 15- 10 - 5 - Mined or restricted Available or available with conditions 3_L <28 28-42 42-66 Seam Thickness (inches) >66 Available or available with Measured Indicated Inferred Reliability Figure 44 Availability of the Herrin Coal by thick- ness category. Figure 45 Availability of the Herrin Coal by reliability category. 43 Table 7 Availability of medium- and low-sulfur Herrin Coal by mining district (millions of tons). Charleston Hornsby Quality Circle Troy Total Original 3,849 777 2,799 933 8,357 Mined 64 (2) 1 28 (4) 2,536 (91) 50 (5) 2,677 (32) Remaining 3,785 (98) 748 (96) 263 (9) 883 (95) 5,678 (68) Available 1,674 (44) 665 (86) 53 (2) 432 (46) 2,825 (34) Available with potential restrictions 32 (1) (0) 65 (2) 249 (27) 346 (4) Technological restrictions 1,977 (51) 61 (8) 69 (2) 159 (17) 2,266 (27) Land-use restrictions 102 (3) 22 (3) 76 (3) 42 (5) 242 (3) 'Numbers in parentheses are percent of original resources. Table 8 Availability of the Herrin Coal by reliability category (billions of tons). Measured Indicated Inferred Total Original Mined Remaining Available 28.6 9.4 19.2 15.0 Available with potential restrctions 0.6 Technological restrictions 2.8 Land-use restrictions 0.8 (33) 1 (67) (52) (2) (10) (3) 34.9 34.9(100) 22.8 (66) 1.7 (5) 8.3 (24) 2.0 (6) 25.0 25.0 (100) 13.2 (53) 0.8 (3) 10.0 (40) 0.9 (4) 88.5 9.4 (11) 79.0 (89) 51.0 (58) 3.1 (3) 21.1 (24) 3.8 (4) 'Numbers in parentheses are percent of original resources. than 42 inches thick (8%), and thin interburden between the Herrin Coal and resources in under- lying or overlying coals (4%). Size of mining block, unfavorable geologic conditions near chan- nels, and Anvil Rock Sandstone in the immediate roof, faults, and partings restrict a total of about 5% of the resources. Block size, Channels, Sandstone & Faults Mined or lost 10% Most of the available resources are in the south- ern half of the state (fig. 47). These available resources are well suited for high-efficiency longwall mining. The resources are relatively flat- lying; have a consistent seam thickness over large areas; are relatively free of faults, channels, or other geologic anomalies; are predominantly in rural areas free from oil wells and other surface development; and occur in minable blocks of hun- dreds of millions of tons. Coal <42" thick 8% Thin bedrock cover 9% Thin interburden 4% Land-use restriction 4% Available with potential restrictions 4% Figure 46 Availability of the Herrin Coal for under- ground mining. The quadrangle assessments of available coal conducted prior to this statewide assessment sampled about 4% of the Herrin Coal resources that are potentially minable by underground methods. In most cases the percentages of resources found to be restricted by individual factors were similar in both the quadrangle and statewide assessments (table 9). These results indicate that the set of quadrangles used to identify criteria was a fairly representative sampling of the mining conditions as- sociated with the Herrin Coal. However, the differences between the statewide and quadrangle assess- ments reveal some shortcomings in the selection of quadrangles. The percentage of available coal was larger and the percentage of tonnage already mined or restricted by land use or block size was smaller 44 Table 9 Resources of the Herrin Coal available for underground mining in this study and previous quadrangle studies (millions of tons). Statewide Quadrangles Original 86,331 3,775 Mined (percent of original) 8,388 (10) 1 487 (13) Remaining (percent of original) 77,943 (90) 3,288 (87) Available 49,299 (57) 1,898 (50) Available with potential restrictions 3,254 (4) 81 (2) Oil wells 1,528 (2) 32 (1) Bedrock 75 to 100 feet thick 1,065 (1) not used Potential land-use conflict 661 (<1) 49 (1) Land-use restrictions 3,611 (4) 326 (9) Towns 1,980 (2) 181 (5) Abandoned mines 775 (<1) 96 (3) Public lands 529 (<1) 1 (<1) Oil wells 230 (<1) not used Roads 92 (<1) 5 (<1) Major airports 2 4 (<1) 6 (<1) Dams <1 (<1) <1 (<1) Railroads not used 7 (<1) Cemeteries not used 11 (<1) Transmission lines not used <1 (<1) Churches and schools not used 1 (<1) Technological restrictions 21,778 (25) 1,000 (26) Thin bedrock cover 3 7,377 (9) 252 (7) Seam <42 inches thick 6,631 (8) 329 (9) Thin interburden 3,354 (4) (0) Block size 2,086 (2) 267 (7) Near channel 4 985 d) 29 0) Sandstone within 5 ft of coal 687 (<1) 11 (<1) Poor roof conditions under Energy Shale 384 (<1) 18 (<1) Faulted 273 (<1) 18 (-t\ C. Eastern Illinois Herrin Coal H Available Restricted or mrned out "~~ — v. Subcrop of the Herrin Coal A 50 Miles Figure 49 Areas of the Herrin Coal available for surface mining. 49 For surface mining, the major technological restrictions are stripping ratio and thickness of drift. These conditions make the cost of surface mining the Herrin Coal too high to compete successfully with local underground mines or with surface-mined coal from western states in today's markets. In most parts of Illinois, land use is a relatively minor restriction for underground mining of the Herrin Coal. The major land-use restrictions on underground mining are related to urban development in the St. Louis metropolitan area and in the vicinity of Peoria. Land use, particularly proximity to towns, is a significant restriction to surface mining. REFERENCES Allsman, P.T., and P.F. 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Papers: American Chemical Society Division of Fuel Chemistry, v. 44, no. 2, p.167-171. Chou, M.-l., J.M. Lytle, S.C. Kung, K.K. Ho, L.L. Baxter, and P.M. Goldberg, 1 998, Effects of chlorine in coal on boiler corrosion, 1995-1998 program, Final report to the Illinois Coal Development Board, Illinois Clean Coal Institute, 28 p. Clegg, K.E., and J.C. Bradbury, 1956, Igneous intrusive rocks in Illinois and their economic signifi- cance: Illinois State Geological Survey Report of Investigations 197, 19 p. DeMaris, P.J., and W. John Nelson, 1990, Geology of the Herrin Coal at Crown II Mine, Virden, Macoupin County, Illinois: Illinois State Geological Survey Reprint Series 1990-D, 16 p. Eggleston, J.R., M.D. Carter, and J.C. Cobb, 1990, Coal resources available for development— A methodology and pilot study: U. S. Geological Survey Circular 1055, 15 p. Gluskoter, H.J., and J.A. Simon, 1968, Sulfur in Illinois coals: Illinois State Geological Survey Circular 432, 28 p. 50 Hopkins, M.E., 1 958, Geology and petrology of the Anvil Rock Sandstone of southern Illinois: Illinois State Geological Survey Circular 256, 49 p. Hsiung, S. M., and S. S. Peng, 1987a, Design guidelines for multiple seam mining, part I: Coal mining, v. 24, no. 9, p. 42-46. Hsiung, S. M., and S. S. Peng, 1987b, Design guidelines for multiple seam mining, part II: Coal mining, v. 24, no. 10, p. 48-50. Illinois Department of Mines and Minerals, 1 954, A compilation of the reports of the mining industry of Illinois from the earliest records to 1954, Springfield, Illinois, 263 p. Jacobson, R.J., C.G. Treworgy, and C. Chenoweth, 1996, Availability of coal resources for mining in Illinois, Mt. Carmel Quadrangle, southeastern Illinois: Illinois State Geological Survey Mineral Note 114, 39 p. 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Jacobson, 1996a, Availability of coal resources for mining in Illinois, Newton and Princeville Quadrangles, Jasper, Peoria and Stark Counties: Illinois State Geological Survey Open File Series 1996-3, 47 p. Treworgy, C.G., C.A. Chenoweth, and M.A. Justice, 1 996b, Availability of coal resources for mining in Illinois, Atwater, Collinsville and Nokomis Quadrangles, Christian, Macoupin, Madison, Montgomery and St. Clair Counties: Illinois State Geological Survey Open File Series 1996-2, 33 p. Treworgy, C.G., C.A. Chenoweth, J.L. McBeth, and OP. Korose, 1997a, Availability of coal resources for mining in Illinois, Augusta, Kewanee North, Mascoutah, Pinckneyville and Roodhouse East Quadrangles, Adams, Brown, Greene, Henry, Perry, Schuyler and St. Clair Counties: Illinois State Geological Survey Open File Series 1997-10, 72 p. Treworgy, C.G., G.K. Coats, and M.H. 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North, 1998, Availability of coal resources for mining in Illinois, Albion South, Peoria West, Snyder-West Union, Springerton and Tallula Quadrangles, Clark, Edwards, Hamilton, Menard, Peoria, Sangamon and White Counties: Illinois State Geological Survey Open File Series 1998-1, 92 p. Treworgy, C.G., and D.L. North, 1999, Availability of coal resources for mining in Illinois, Shawneetown Quadrangle, Gallatin County: Illinois State Geological Survey Open File Series 1999-7, 35 p. Treworgy, C.G., D.L. North, C.L. Conolly, and L. Furer, 1999b, Coal resources map and availability of Coal for mining, Vincennes Quadrangle, Lawrence County, Illinois and Knox County, Indiana: Illinois State Geological Survey IGQ Vincennes-CR. Treworgy, C.G., E.I. Prussen, M.A. Justice, C.A. Chenoweth, M.H. Bargh, R.J. Jacobson, and H.H. Damberger, 1997b, Illinois coal reserve assessment and database development: Final report, Illinois State Geological Survey Open File Series 1997-4, 105 p. Wood, G.W., Jr., T.M. Kehn, M.D. Carter, and W.C. Culbertson, 1983, Coal resource classification system of the U.S. Geological Survey: U.S. Geological Survey Circular 891, 65 p. 52 APPENDIX 1 Source maps for coal resources. Source Map Scale County (ISGS publications) year (x1000) Bond Treworgy et al. 1 997 1996 50 Bureau Cady 1952, Smith and Berggren 1963 1950 125 Cass This study 1999 50 Champaign Treworgy and Bargh 1 982 1978 1 62.5 Christian Treworgy and Bargh 1 982 1978 62.5 Clark Treworgy et al. 1 997 1996 50 Clay Allgaier and Hopkins 1975 1975 125 Clinton Treworgy et al. 1 997 1996 50 Coles Treworgy et al. 1 997 1996 50 Crawford Treworgy et al. 1 997 1996 50 Cumberland Treworgy et al. 1 997 1996 50 DeWitt This study 1999 50 Douglas Treworgy et al. 1997 1996 1 50 Edgar Treworgy et al. 1 997 1996 1 50 Edwards Treworgy and Bargh 1 982 1978 62.5 Effingham Treworgy et al. 1 997 1996 50 Fayette Treworgy et al. 1 997 1996 50 Franklin Treworgy and Bargh 1 982 1978 62.5 Fulton Smith and Berggren 1963 1963 125 Gallatin Treworgy and North 1999, Smith 1957 Treworgy and Bargh 1 982 1999 1 62.5 Greene Smith 1961 1961 125 Grundy Jacobson 1985 1985 62.5 Hamilton Treworgy and Bargh 1 982 1978 62.5 Henry Smith and Berggren 1963 1963 125 Jackson Smith 1958 1958 125 Jasper Treworgy et al. 1 997 1996 50 Jefferson Treworgy and Bargh 1 982 1978 62.5 Jersey Smith 1961 1961 125 Knox Smith and Berggren 1963 1963 125 La Salle Jacobson 1985 1985 62.5 Lawrence Treworgy et al. 1 997 1996 50 Livingston Jacobson 1985 1985 62.5 Logan Work map by J. Treworgy 1983 1 62.5 McLean This study 1999 50 Macon Treworgy and Bargh 1 982 1978 1 62.5 Macoupin Smith 1963, Treworgy and Bargh 1982 1963 1 62.5 Madison Smith 1963, Treworgy and Bargh 1982 1963 62.5 Marion Treworgy and Bargh 1 982 1978 62.5 Marshall Cady 1952 1950 62.5 Menard This study 1999 50 Monroe Smith 1958 1958 125 Montgomery Treworgy and Bargh 1982 1978 1 62.5 Morgan This study 1999 50 Moultrie Treworgy et al. 1 997 1996 1 50 Peoria Smith and Berggren 1963 1963 125 (continued) 53 APPENDIX 1 (continued) Source maps for coal resources. Source Map Scale County (ISGS publications) year (x1000) Perry Smith 1 958, Treworgy and Bargh 1 982 1978 62.5 Piatt This study 1999 50 Putman Treworgy and Bargh 1 982 1978 62.5 Randolph Smith 1958, Treworgy and Bargh 1982 1958 125 Richland Treworgy et al. 1 997 1996 50 St. Clair Smith 1958, Treworgy and Bargh 1982 1978 125 Saline Smith 1 957, Treworgy and Bargh 1 982 1978 125 Sangamon Treworgy and Bargh 1 982 1978 1 62.5 Scott This study 1999 50 Shelby Treworgy et al. 1 997 1996' 50 Stark Cady 1952, Smith and Bergren 1963 1950' 125 Tazewell Smith and Berggren 1963, Treworgy and Bargh 1982 1978 1 125 Vermilion Jacobson and Bengal 1981, this study 1999 62.5 Wabash Treworgy and Bargh 1982 1978 62.5 Washington Treworgy and Bargh 1982 1978 62.5 Wayne Treworgy and Bargh 1982 1978 62.5 Williamson Smith 1 957, Treworgy and Bargh 1 982 1978 125 Woodford This study 1999 50 1 Minor revisions made for this report. 54