Planned Coal Mine Subsidence In Illinois
State of IllinoisRod. R. Blagojevich, GovernorIllinois Department of Natural ResourcesIllinois State Geological SurveyPlanned Coal MineSubsidence in Illinois:A Public Information BookletRobert A. BauerCircular 5732008
Equal opportunity to participate in programs of the Illinois Department of Natural Resources (IDNR)and those funded by the U.S. Fish and Wildlife Service and other agencies is available to all individualsregardless of race, sex, national origin, disability, age, religion, or other non-merit factors. If you believeyou have been discriminated against, contact the funding source’s civil rights office and/or the EqualEmployment Opportunity Officer, IDNR, One Natural Resources Way, Springfield, Illinois 62701-1271;217-785-0067; TTY 217-782-9175.This information may be provided in an alternative format if required. Contact the IDNR Clearinghouseat 217-782-7498 for assistance.Front Cover (clockwise from upper left): Garage raised and kept level during subsidence; restored houseafter subsidence; unoccupied house on subsided land (white line shows level of the original ground surface); a road subsided over a longwall panel before mitigation repaired it.Released by the authority of the State of Illinois10M - 5/08
Planned Coal MineSubsidence in Illinois:A Public Information BookletRobert A. BauerCircular 5732008Illinois Department of Natural ResourcesILLINOIS STATE GEOLOGICAL SURVEYWilliam W. Shilts, Chief615 E. Peabody DriveChampaign, Illinois 61820-6964217-333-4747www.isgs.uiuc.edu
CONTENTSIntroductionOrigin and Formation of CoalCoal Mining and Coal Reserves in IllinoisReserves and LocationUnderground Coal Mining MethodsRoom-and-Pillar MiningMines in the Early 1900sModern MinesSubsidence and Room-and-Pillar MinesHigh-Extraction Retreat MiningLongwall MiningSubsidenceHistory of Subsidence ResearchMechanics of SubsidenceSubsidence MovementsVertical SubsidenceTiltStrainSubsidence Related to Time and Coal Face AdvanceSubsidence MonitoringFederal and State RegulationsFederal LawState LawPlanned Subsidence RegulationMine Subsidence InsuranceInformation SourcesIllinois Mine Subsidence Research ProgramEffects of Planned SubsidenceFarmlandMitigationSoilsOverburden and GroundwaterMine DesignStructuresAdvantages of Planned SubsidenceImmediate and Predictable SubsidenceImproved Mine ProductivityDamage and RepairLandStructuresRoads, Railroads, and PipelinesBuilding Damage from Other CausesMarket CompetitionAcknowledgmentsReferencesContacts for Additional 31313141414141414151516171719
FIGURES123456789101112131415This statewide map of Illinois shows the extent of coal in Illinois and thelocation of mined-out areas from surface and underground coal miningThe conceptual diagram illustrates the parts of a modern coal mineFailure of a coal mine floor is shownThis diagram of a high-extraction retreat panel shows the small stumpsof coal pillars left for safety during mining and the chain pillars that maybe mined to increase coal extractionThe longwall mining equipment photograph shows hydraulic shieldsupports and cutting drumThis schematic diagram shows the general behavior of overburden abovelongwall panels and the location of surface subsidence featuresThe development of surface subsidence is affected by the width of theextracted area (panel) in relation to depth of miningThe position of an advancing longwall face is shown in relation to thelocation of major surface movements occurring behind the mining operationThe percentage of subsidence is shown in relation to the width-to-depthratio for longwall and high-extraction mines in IllinoisThe coal company took measures to protect this home in advanceof subsidenceThis unoccupied structure located above the centerline of a longwall panelwas subsided 4.5 feetAerial photos were used to locate subsided areas for study of the effects ofunmitigated subsidence on corn yieldsExamples of a road subsided over a longwall panel and repairedThis railroad grade was re-established after longwall coal mine subsidenceby increasing the vertical amount of crushed rock (ballast) below rails wherelongwall panels crossed under the tracksThis subsided pipeline was successfully undermined by several longwalls234556788101112151616
IntroductionThe trend toward coal mining methodsthat use planned subsidence continuesin Illinois and elsewhere in the UnitedStates. Real concerns about possibleeffects of mining and geologic conditions on the state’s water resources,farmland productivity, and structureswere investigated during 9 years ofresearch under the Illinois Mine Subsidence Research Program (IMSRP).This program was established by theIllinois Coal Association and the Illinois Farm Bureau in 1985 to investigatethe impacts of planned subsidencemining methods in the state. In addition to the research findings, miningcompanies and regulatory agencies inIllinois have had 30 years of experiencewith over 240 modern mechanizedlongwall panels in 6 Illinois counties (Barkley 2007). This circular wasproduced to respond to communityconcerns about the possible effects ofunderground mining and surface subsidence (the sinking of land surface).The publication also provides background information on the coal industry and mining methods that will helpincrease understanding of plannedsubsidence.The Illinois coal mining industry useshigh-extraction mining methods, suchas longwall, in areas where it has theright to subside the ground surface.Planned subsidence using the longwallmining method enables Illinois coalmine operators to maximize miningproductivity and decrease the per toncost of the delivered product, thusimproving coal’s marketability. Also,high-extraction mining methods conserve and extend coal resources forfuture use by wasting less coal thanother methods that leave considerableamounts of coal behind.Longwall mining in Illinois is not new.A longwall method that extracted coalmostly by hand was used from 1856to 1954. Over 135 mines in 15 counties used this method. This longwallmethod started in Great Britain inthe late 1600s (Hatcher 1993). Later,a fully mechanized method started inEurope and began to be used duringthe 1950s and 1960s in the UnitedStates. Longwall mining is currentlyIllinois State Geological Surveyused in 12 states with 52 operatinglongwalls (Fiscor 2007). Worldwidemechanized longwall mining is usedin United Kingdom, Germany, Poland,Russia, China, India, South Africa, andAustralia.The main purchasers of Illinois coalare electric power-generating stations.Coal generates about 50% of the electricity in Illinois and the nation. As of2007, several new conventional powergenerating stations in Illinois are beingplanned, and plants that will produceelectricity with coal that is first turnedinto a gas (gasification) are beingconsidered. Also, because of increasing petroleum prices and dwindlingresources, there is renewed interest inthe United States for plants that produce liquid fuel products (gasoline, jetfuels, and diesel) from coal as has beendone in several other countries for overhalf a century.Origin and Formationof CoalCoal is called a fossil fuel because it ismade up of materials that were onceliving plants. The stored energy fromthe ancient plant materials is releasedwhen the coal is burned (Illinois CoalAssociation 1992). One of the majorcoal-forming periods began about 320million years ago during Pennsylvaniantime when much of what is now theUnited States was repeatedly coveredby swamps where giant ferns, reeds,and other plants grew. When the plantsdied, they fell into the swamp waterand accumulated. The plant material, deprived of oxygen after it wasburied, did not decay but formed peat.Over time, the peat was compacted,covered by layers of other materials,and eventually dried and hardened.The formation of individual minablecoal beds took place over many tens ofthousands of years. Under conditionsof increasing burial, and thus increasing pressure and temperature, the peatwas transformed into coal. From softest to hardest, the stages (rank) of coalformation after peat are lignite, subbituminous, bituminous, and anthracitecoal. The harder the coal, the moreenergy it contains per unit volume. Thecoal mined in Illinois is bituminous.Coal Mining and CoalReserves in IllinoisHistorians date the discovery of bituminous coal in America by Europeansto a sighting in 1673 in what is now theOttawa-Utica area of Illinois. The discovery is attributed to explorers Jollietand Marquette. Jolliet’s map of 1674shows the location of charbon de terre(coal) (Andros 1915).Commercial mining in Illinois isthought to have started about 1810 inJackson County. Coal mined there wasbarged down the Big Muddy River andMississippi River to New Orleans. Inthe early 1820s, boats loaded with coalin Peoria also made their way to NewOrleans. Early mines were located nearrivers, where entrances were cut intoseams exposed in the bluffs (called adrift entrance). Later, shaft mines (vertical entrance) were started in Bellevillein the early 1840s. By 1900, coal wasproduced in at least 52 Illinois counties to supply commercial industriesin towns such as St. Louis and Chicagoand to fuel local residential furnacesand stoves (Illinois Coal Association1992). Towns grew up around themines and railroads, which were alsomajor users of coal and suppliers ofmuch of the transportation. As a result,many urban and residential areasare built over or near old abandonedmines in Illinois. A new study (Korose2008, personal communications) foundthat about 333,100 housing units wereover or adjacent to the 839,000 acresundermined for coal in Illinois. Thisstudy used the 2000 census and landcover data along with the 2007 mineoutline information.The expansion of the railroad systemallowed mines to be located fartherfrom their markets than they wereduring the early days of mining. Todaymost underground mines are locatedin southern Illinois, and a few arefound in the central part of the state(Illinois Office of Mines and Minerals2005). Underground mines in Illinoisoperate at 220 to 1,006 feet below theground surface; average depth is 445feet (Illinois Department of Commerceand Economic Opportunity 2006). In2005, underground mines producedCircular 5731
83% of the annual tonnage mined inthe state; the other 17% came fromsurface mining (Illinois Office of Minesand Minerals 2005).WINNEBAGOSTEPHENSONJO DAVIESSCARROLLBOONELAKEMCHENRYOGLEKANEDE KALBCOOKReserves and LocationLEEWILLKENDALLLA DERSOWOODFORDHENIllinois has abundant coal resources.All or parts of 86 of the 102 countiesin the state have coal-bearing rocksbelow them. Figure 1 shows where coalis present in Illinois and the locationof mined-out areas. As of 2007, about1,050,400 acres (about 2.8% of thestate) have been mined out for coal:836,655 acres by underground miningand 213,725 acres by surface mining.In 2005, Illinois ranked ninth nationwide in coal production, and the state’sannual total coal production was about32 million tons (www.eia.doe.gov).Illinois is first in the nation for reservesof bituminous coal, the country’s mostwidely used coal rank (Illinois Department of Mines and Minerals 1990, Illinois Coal Association 1992).DU ELLVERMILIONCHAMPAIGNMASONLOGANSCHUYLERDE ASSANGAMONPIKEMOULTRIESCOTTUnderground CoalMining ARIONCLINTONNSWARD40 miJEFFERSONWABASHWAYNEWASHINGTONED0ST. CLAIR050 ACKSONSALINEGALLATINWILLIAMSONundergroundextent ofPennsylvanian ircular 573GREENEOU N2COLESSHELBYMACOUPINCA LHUnderground mining methods haveevolved as technology has changed andas laws have been enacted to regulatethe industry. Room-and-pillar, high-extraction retreat, and longwall are threemodern methods used to mine coal.Current methods reflect the coal companies’ compliance with federal andstate regulations requiring approvedmine plans, improved ventilation, roofsupport plans, and liability for surfaceeffects of subsidence. Coal companiesin Illinois continue to use high-extraction mining methods to decrease costsand improve productivity, but roomand-pillar (low-extraction) methodsare still used in most of the mines.Longwall mining requires a high initialcapital investment for equipment, anexpense many smaller coal companiescannot afford, and the method requireslegal rights to subside the ground surface. Figure 2 depicts the surface andunderground facilities of a modernmine.CHRISTIANFigure 1 This statewide map of Illinois shows the extent of coal and the location ofmined-out areas from surface and underground coal mining (Bauer 2006).Illinois State Geological Survey
Illinois State Geological SurveyCircular 5733JKFLGMNIDSURFACE FACILITIES:1. Transfer Building2. Raw Coal Conveyer3. Raw Coal Solo4. Breaker Building5. Preparation Plant6. Thickener7. Thermal Dryer8. Plant Sample Building9. Clean Coal Silo10. Railroad Loadout11. Railroad12. Refuse Conveyer13. Shuttle Car78DIE5OR6P91213104S10 11Q3Figure 2 The conceptual diagram illustrates the parts of a modern coal mine. (Diagram used by permission of Consol, Inc.)HEIndicates Return AirIndicates Intake AirUNDERGROUND MINE:A. Portal FacilitiesB. Exhaust FanC. Ventilation ShaftD. Longwall Mining SectionE. GOBF. ShearerG. ShieldH. ConveyorI. Continuous Mining SectionJ. Continuous MinerK. Integrated Roof BoltersL. Loading MachineM. Shuttle CarN. Section FanO. Section Conveyer BeltP. TrackQ. Slope BeltR. StoppingS. OvercastBCArea Shownin IllustrationA2Current LongwallOperation1
Room-and-Pillar MiningMines in the Early 1900s Manymines at the turn of the last centuryhad entries varying in length, width,and direction, forming irregularmining patterns. After about 1910,mining was conducted with a moresystematic pattern of rooms and pillars. In the production areas, or panels,workers created rooms and crosscutsat right angles to form a grid pattern.The widths of these rooms ranged fromabout 20 to 40 feet (Hunt 1980). Blocksof coal called pillars were left unminedto support the roof of the mine andthe surface. In the older mines (1930sand before), 40% to 80% of the coalwas extracted (Hunt 1979). Most of thesubsidence problems associated withthe room-and-pillar method occursover higher extraction areas of theseolder mines. Subsidence from theseold room-and-pillar mining operationscan occur at any time after mining,from a few years to decades to centuries afterward. More information aboutthe design of older mines can be foundin Mine Subsidence in Illinois: Facts forHomeowners (Bauer 2006).A distinction should be made betweenthese older mines and modern (post1983) room-and-pillar mines, whichare designed on the basis of thestrength of the local geology to preventsubsidence as required by the 1983 federal and state regulations.Modern Mines In modern roomand-pillar mines, production areas arestill called panels. Figure 2 shows thecheckerboard pattern of a room-andpillar area. The modern room-andpillar mine is designed to leave enoughcoal unmined in pillars to support theoverburden and prevent subsidence.Modern mines have a regular configuration of production areas and entryways. The widths of rooms and entriesin modern mines range from 18 to 24feet, which is considerably narrowerthan those in older mines (Hunt 1980).The machine used to make passageways or entries through the coal iscalled a continuous miner. In the continous mining process, workers installroof bolts (steel anchors) in the mineroof to support it as the continuous4Circular 573miner advances. The unmined areasbetween the panels and between theentries and the panels are called barrier pillars. Modern room-and-pillarmining generally recovers less than50% to 60% of the coal. Regulationsfor securing permits for this miningmethod require analysis to show thatthe size of pillars and amount of coalremoved will result in a stable underground mine opening and will beexpected to not fail and subside theground surface.Subsidence and Room-and-PillarMines Subsidence is possiblewherever coal has been removed in aroom-and-pillar mine. The roof, pillars, and floor are the components thatsurround the openings in a room-andpillar mine, and the capacity of thesecomponents to keep an entry open andmaintain a stable working area (andthus prevent subsidence) is based ontheir geologic characteristics and properties.Floor failure is the most commoncause of subsidence in Illinois inmodern room-and-pillar mines. Theclaystone that is usually found underneath Illinois coal seams is weakerthan the coal or the roof rock, a condition that makes the floor the mostunstable component in the mine (Hunt1980). When the floor of the mine fails,the weak claystone beneath a pillar issqueezed out from underneath, liketoothpaste, into the mine opening,which allows the pillar to sink into thefloor (fig. 3). Another failure in shallow mines can lead to subsidence. Theimmediate rock above the mine entrycan weaken and fall into the mine void.These roof falls are minimized but notalways prevented by placing bolts intothe roof in a set pattern. Roof falls arestill a threat to miner’s safety even inmodern mines. In most cases, roof fallsmine roofcoalpillarmine floorfloor failureFigure 3 Failure of a coal mine floor isshown.are not considered to be a cause ofsubsidence; however, when the mineis located at a very shallow depth (lessthan 200 to 300 feet), and the bedrockbetween the mine level and the groundsurface is thin (tens of feet) and contains no competent layer such as limestone, holes or pits may form on theground surface. Pillar failures are rarein modern mines.High-Extraction RetreatMiningNo Illinois mines currently use highextraction retreat mining, but from the1940s to 2002, this method was usedin mines of several companies in thestate. High-extraction retreat miningoperations first develop a room-andpillar panel. The miners then systematically begin taking additional coalfrom the pillars that were left behind.This secondary extraction occurs in aretreating fashion, working from theouter edges of the panel back to themain entries. Most coal pillars, whichsupport the roof, are removed shortlyafter a few rows of rooms and pillars have been formed, leaving onlysmall pillars called stumps or fenders.The high-extraction retreat processrecovered more coal (up to 80 to 90%in a panel) than did room-and-pillarmining. In high-extraction retreatmining, the size and number of pillars that had to be left to maintainworker safety varied with undergroundgeologic conditions (Hunt 1980). Theroof collapsed in a manner that wascontrolled by temporary supports, andplanned subsidence of the surface wasinitiated immediately. Sometimes pillars were left unmined in a certain areato control surface subsidence and protect a structure. Figure 4 shows a highextraction retreat panel. This method,in older operations, was also calledpillar extraction, punching pillars, pulling pillars, or pillar robbing.Longwall MiningIn the United States, mining companies began using the fully mechanizedlongwall method in the 1950s and1960s, although the method was developed and used much earlier in Englandand Europe. A completely differenttype of equipment is used in longwallIllinois State Geological Survey
minedoutstumpsorfendersworkingfaceto beminedminingdirectionchainpillarpanel width200 ftpanel extraction: 70–90%panel width: 400–600 feetFigure 4 This diagram of a high-extraction retreat panel shows the smallstumps of coal pillars left for safetyduring mining and the chain pillars thatmay be mined to increase coal extraction (Hunt 1980).mining than is used in room-and-pillaror high-extraction retreat mining. Inlongwall mi
In 2005, Illinois ranked ninth nation-wide in coal production, and the state’s annual total coal production was about 32 million tons (www.eia.doe.gov). Illinois is first in the nation for reserves of bituminous coal, the country’s most widely used coal rank (Illinois Depart-ment of Mines and Minerals
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Model Coal Mine Development and Production Agreement for Detailed Explored Blocks Ver -3 .0, 03 February 2014 5 COAL MINE DEVELOPMENT AND PRODUCTION AGREEMENT This COAL MINE DEVELOPMENT AND PRODUCTION AGREEMENT (this "Agreement") is made this [ ] day of [ ], [2014] ("Effective Date") at [insert location], India, by and between:
Coal deposits are mined by cutting a network of 'roads' into the coal seam & leaving behind 'pillars' of coal to support the roof of the mine. These pillars can be up to 40% of the total coal in the seam - although this coal can sometimes be recovered at a later stage by 'retreat mining'.The roof is then allowed to collapse and the mine is
as.edu / n e Resources -Coal 1 Based on -The Coal Resource by World Coal Institute 2005.-The Coal Resource Base, Chapter 2 of Producing Liquid Fuels from Coal by J.T. Bartis, F. Camm and D.S. Ortiz. Published by RAND 2008. ISBN: 978--8330-4511-9. -The Role of Coal in Energy Growth and CO2 Emissions, Chapter 2 of The Future of Coal, an Interdisciplinary MIT Study, 2007.
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BAR and BAN List – Topeka Housing Authority – March 8, 2021 A. Abbey, Shanetta Allen, Sherri A. Ackward, Antonio D. Alejos, Evan Ackward, Word D. Jr. Adams .
