363. /009773 ey _ The cop.4 5 4D eee Changi Illinois Environment: y Uy uf Ane a Fs yn p str Ste ih BF ans, a See Gy _/A / AN nois Department of ergy and Natural Resources June 1994 ILENR/RE-EA-94/05(4) Natural History Survey Library ILENR/RE-EA-94/05(4) The Changing Illinois Environment: Critical Trends Technical Report of the Critical Trends Assessment Project Volume 4: Earth Resources Illinois Department of Energy and Natural Resources Illinois State Geological Survey Division 615 East Peabody Drive Champaign, Illinois 61820 June 1994 Jim Edgar, Governor State of Illinois John S. Moore, Director Illinois Department of Energy and Natural Resources 325 West Adams Street, Room 300 Springfield, Illinois 62704-1892 Printed by Authority of the State of [linois Printed on Recycled and Recyclable Paper Illinois Department of Energy and Natural Resources 325 West Adams Street, Room 300 Springfield, Illinois 62704-1892 Citation: Illinois Department of Energy and Natural Resources, 1994. The Changing Illinois Environ- ment: Critical Trends. Summary Report and Volumes 1 - 7 Technical Report. Illinois Department of Energy and Natural Resources, Springfield, IL, ILENR/RE-EA-94/05. Volume 1: Air Resources Volume 2: Water Resources Volume 3: Ecological Resources Volume 4: Earth Resources Volume 5: Waste Generation and Management Volume 6: Sources of Environmental Stress Volume 7: Bibliography ABOUT CTAP ABOUT THE CRITICAL TRENDS ASSESSMENT PROJECT The Critical Trends Assessment Project (CTAP) is an on-going process established to describe changes in ecological conditions in Illinois. The initial two-year effort involved staff of the Illinois Department of Energy and Natural Resources (ENR), including the Office of Research and Planning, the Geological, Natural History and Water surveys and the Hazardous Waste Research and Information Center. They worked with the assistance of the Illinois Environ- mental Protection Agency and the Illinois depart- ments of Agriculture, Conservation, Mines and Minerals, Nuclear Safety, Public Health, and Trans- portation (Division of Water Resources), among other agencies. CTAP investigators adopted a “source-receptor” model as the basis for analysis. Sources were defined as human activities that affect environmental and ecological conditions and were split into categories as follows: manufacturing, transportation, urban dynamics, resource extraction, electricity generation and transmission, and waste systems. Receptors in- cluded forests, agro-ecosystems, streams and rivers, lakes, prairies and savannas, wetlands, and human populations. The results are contained in a seven-volume technical report, The Changing Illinois Environment: Critical Trends, consisting of Volume 1: Air Resources, Volume 2: Water Resources, Volume 3: Ecological Resources, Volume 4: Earth Resources, Volume 5: Waste Generation and Management, Volume 6: Sources of Environmental Stress, and Volume 7: Bibliography. Volumes 1-6 are synopsized in a summary report. The next step in the CTAP process is to develop, test, and implement tools to systematically monitor changes in ecological and environmental conditions in Illinois. Given real-world constraints on budgets and human resources, this has to be done in a practi- cal and cost-effective way, using new technologies for monitoring, data collection and assessments. As part of this effort, CTAP participants have begun to use advanced geographic information systems (GIS) and satellite imagery to map changes in Illi- nois’ ecosystems and to develop ecological indicators (similar in concept to economic indicators) that can be evaluated for their use in long-term monitoring. The intent is to recruit, train, and organize networks of people — high school science classes, citizen vol- unteer groups — to supplement scientific data collec- tion to help gauge trends in ecological conditions. Many of the databases developed during the project are available to the public as either spreadsheet files or ARC-INFO files. Individuals who wish to obtain additional information or participate in CTAP programs may call 217/785-0138, TDD customers may call 217/785-0211, or persons may write: Critical Trends Assessment Project Office of Research and Planning Illinois Department of Energy and Natural Resources 325 West Adams Street, Room 300 Springfield, IL 62704-1892 Copies of the summary report and volumes 1-7 of the technical report are available from the ENR Clearinghouse at 1/800/252-8955. TDD customers call 1/800/526-0844, the Illinois Relay Center. CTAP information and forum discussions can also be accessed electronically at 1/800/528-5486. FOREWORD FOREWORD "If we could first know where we are and whither we are tending, we could better judge what we do and how to do it..." Abraham Lincoln Imagine that we knew nothing about the size, direction, and composition of our economy. We would each know a little, i.e., what was happening to us directly, but none of us would know much about the broader trends in the economy — the level or rate of housing starts, interest rates, retail sales, trade deficits, or unemployment rates. We might react to things that happened to us directly, or react to events that we had heard about — events that may or may not have actually occurred. Fortunately, the information base on economic trends is extensive, is updated regularly, and is easily accessible. Designed to describe the condition of the economy and how it is changing, the information base provides the foundation for both economic policy and personal finance decisions. Typical economic decisions are all framed by empirical knowledge about what is happening in the general economy. Without it, we would have no rational way of timing these decisions and no way of judging whether they were correct relative to trends in the general economy. Unfortunately, this is not the case with regard to changes in environmental conditions. Environmental data has generally been collected for regulatory and management purposes, using information systems designed to answer very site-, pollutant-, or species- specific questions. This effort has been essential in achieving the many pollution control successes of the last generation. However, it does not provide a systematic, empirical database similar to the eco- nomic database which describes trends in the general environment and provides a foundation for both environmental policy and, perhaps more importantly, personal decisions. The Critical Trends Assessment Project (CTAP) is designed to begin developing such a database. As a first step, CTAP investigators inventoried existing data to determine what is known and not known about historical ecological conditions and to identify meaningful trends. Three general conclu- sions can be drawn from CTAP’s initial investiga- tions: Conclusion No. 1: The emission and discharge of regulated pollutants over the past 20 years has declined, in some cases dramatically. Among the findings: ¢ Between 1973 and 1989, air emissions of particulate matter from manufacturing have dropped 87%, those of sulfur oxides 67%, nitrogen oxides 69%, hydrocarbons 45%, and carbon monoxide 59%. ¢ Emissions from cars and light trucks of both carbon monoxide and volatile organic com- pounds were down 47% in 1991 from 1973 levels. ¢ Lead concentrations were down substantially in all areas of the state over the 1978-1990 period, reflecting the phase-out of leaded gasoline. ¢ From 1987 to 1992, major municipal sewage treatment facilities showed reductions in loading of biological/carbonaceous oxygen demand, ammonia, total suspended solids and chlorine residuals that ranged from 25 to 72%. * Emissions into streams of chromium, copper, cyanide, and phenols from major non-municipal manufacturing and utility facilities (most of them industrial) also showed declines over the years 1987-1992 ranging from 37% to 53%. Conclusion No. 2: Existing data suggest that the condition of natural ecosystems in Illinois is rapidly declining as a result of fragmentation and continual stress. Among the findings: e Forest fragmentation has reduced the ability of Illinois forests to maintain biological integrity. In one Illinois forest, neotropical migrant birds that once accounted for more than 75% of breeding birds now make up less than half those numbers. FOREWORD e In the past century, one in seven native fish species in Lake Michigan was either extirpated or suffered severe population crashes and exotics have assumed the roles of major predators and major forage species. * Four of five of the state’s prairie remnants are smaller than ten acres and one in three is smaller than one acre — too small to function as self- Sustaining ecosystems. e Long-term records of mussel populations for four rivers in east central Illinois reveal large reduc- tions in numbers of all species over the last 40 years, apparently as suitable habitat was lost to siltation and other changes. ¢ Exotic species invasions of Illinois forests are increasing in severity and scope. Conclusion No. 3: Data designed to monitor compli- ance with environmental regulations or the status of individual species are not sufficient to assess ecosys- tem health statewide. Among the findings: e Researchers must describe the spatial contours of air pollutant concentrations statewide using a limited number of sampling sites concentrated in Chicago and the East St. Louis metro area. ¢ Much more research is needed on the ecology of large rivers, in particular the effects of human manipulation. e The length of Illinois’ longest stream gaging records is generally not sufficient to identify fluctuations that recur less frequently than every few decades. ¢ The Sediment Benchmark Network was set up in 1981 with some 120 instream sediment data stations; by 1990 the network had shrunk to 40 stations, the majority of which have data for only one to three years. CTAP is designed to begin to help address the complex problems Illinois faces in making environ- mental policy on a sound ecosystem basis. The next edition of the Critical Trends Assessment Project, two years hence, should have more answers about trends in Illinois’ environmental and ecological conditions to help determine an effective and economical environmental policy for Illinois. rt teen ied hasinestic iS ou hore je al xt ‘cation Taarinaeaenay a aaa wie ‘ypyene Si any — “) Btu or quads in 1963 to about 4.2 quads in 1978 (fig. 3)—a trend interrupted by declines in 1974 and 1975 as a result of the dramatic oil price increases brought on by the Middle East war. (See bibliography for data sources.) The average annual growth rate in energy consumption in Illinois between 1963 and 1978 was about 3%. Energy conservation mea- sures were effectively implemented during the 1979- 1980 period of energy price increases due to the Iran- Iraq conflict and U.S. price decontrols. Illinois’ ener- gy consumption fell 20% in 4 years to 3.35 quads in 1982. Since then, consumption has risen inconsistently at an average rate of increase of 0.7% per year to 3.55 quads in 1990. Some increases in energy consumption since 1985 are due to a shift in the consumption pattern in favor of electricity, especially in the residential, com- mercial, and industrial sectors. quadrillion BTU [e*) pS 1965 1970 1975 1980 1985 1990 Figure 3 Energy consumption trend in Illinois. Emissions of sulfur dioxide, nitrogen oxide, particulate matter, and carbon dioxide have decreased with the de- cline in total energy consumption since 1978. But the improvement in air quality is greater than the corre- sponding reduction in total energy consumption seems to indicate because an increasing amount of electricity is being generated by nuclear power plants. Nuclear electricity accounted for about 1% of total generation in the early 1960s. By 1990, about 56% of electricity was generated by nuclear power plants. The potential in- creases in emissions of CO2, SOx, NOx, and particulates were substantially held down by the growth in nuclear electricity. Nuclear energy may further increase its role in electric- ity generation as power plants overcome minor, unfore- seen disruptions and stablize production. No new nuclear plants have been permitted in the past 15 years, so the future mix of energy consumption will depend primarily on how efficiently energy is used in the IIli- nois economy, and how decommissioning of nuclear power plants is paid for. Despite nuclear energy, the consumption of coal for elec- tricity generation in 1990 was about 42% higher than it was in 1960 because the overall demand for electricity was higher; however, the high point of coal consump- tion in the electricity sector was reached in 1980 at 71% above the 1960 level of consumption. The efficiency of energy consumption can be measured by the inflation-adjusted dollar amount of the Gross State Product (GSP) per unit of energy consumed. Fig- ure 4 represents, in terms of 1987 U.S. dollars, the GSP for each 1 million Btu of energy consumed. From 1963 to 1972, when the cost of energy was low, the efficiency measure fell from about $52 to $46 per million Btu. The efficiency of energy use improved to about $48 in the 6 years leading to 1978 and has since then rapidly grown to about $70 per million Btu in 1990. The efficiency of energy use should continue to grow in the residential, commercial, and transportation sectors as the efficien- cies of building insulation, machinery, and appliances and automobile milage per gallon continue to improve. The magnitude of improvements remains uncertain because energy prices in general have stabilized and government codes and tax policies continue to change. Efficiency improvements in the electricity sector have been slow. Although the heat rates (the amount of energy needed to generate 1 kWh of electricity) have improved by about 10% since the 1960s, about two- thirds of all energy input continues to be lost. QUANTITY AND QUALITY OF COAL CONSUMPTION 2 QUANTITY AND QUALITY _, 66 OF COAL CONSUMPTION 64 & 62 E 60 Subhash B. Bhagwat B58 Illinois State Geological Survey S 56 s 54 Total coal consumption in Illinois fell from 45 million 52 tons in 1969 to 32.5 million tons in 1990 (fig. 5). About 50 80% of the 1969 consumption was accounted for by IIli- 48 nois coal; the rest was imported from other states east of 446+— st a the Mississippi. With the advent of large-scale coal min- 1963 1970 1975 1980 1985 1990 ing in Wyoming and Montana in the 1970s, imports into Figure 4 Illinois’ energy efficiency. Illinois increased, mostly at the expense of in-state resources. By 1980, Illinois’ share of total consumption Major energy savings can be achieved with every per- had fallen to 51%. Western coals accounted for about centage point increase in the efficiency of converting 38% and other eastern coals for 11% of consumption. primary energy into electrical energy. Currently, about one-quarter of Illinois’ total energy consumption is Two factors played the most important role in this de- accounted for by losses during the generation of electric- cline in the use of Illinois coal within the state: the low ity. As older, less efficient power plants are replaced by sulfur content of western coals and its low mine-mouth newer designs (currently on the drawing boards), effi- price. Although transportation costs often more than ciency will continue to improve. New technologies such made up for the price difference, many utilities switched as the Integrated Gasification Combined Cycle (IGCC) to low sulfur western coal to comply with requirements could play an important role in this respect; however, of the Clean Air Act regulations on SO2 emissions, flue-gas scrubbers and other conventional pollution con- which went into effect in June 1971. trol devices consume energy and reduce the overall effi- ciency of electricity generation. In the 1980s, the consumption of Illinois coal in the state stabilized at about 20 million tons (about 60% of consumption), while western imports declined sharply to 20% and eastern imports increased steadily, also to about 20% of total consumption. Revision of the Clean Air Act in 1977, increased productivity in Illinois mines, a general shift toward mining of lower sulfur coals in states east ‘of the Mississippi, and more 50 45 40 35 30 eastern Import 25 western Import 20 million tons Illinois coal | 1 970 , 1975 1980 1985 1990 Figure 5 Coal consumption in Illinois. QUANTITY AND QUALITY OF COAL CONSUMPTION sophisticated coal cleaning technologies all helped to bring about the stabilization. Other influential stabilizing factors were the increasing role of nuclear power and declining energy prices after 1981. Electric utilities used the changed circumstances to reduce their dependence on higher priced western coals. The role of nuclear energy is especially promi- nent during the 1980s when coal consumption by elec- tric utilities in Illinois dropped from 36 million tons in 1980 to 27 million tons in 1990 (fig. 6). Nuclear-gener- ated electricity increased its share of the market from 27% to 56%. As Illinois utilities consumed more western coal in the 1970s, the average heat value of coal consumed began to decline (fig. 7), falling from about 10,750 Btu/Ib in 1969 to about 10,250 Btu/lb in 1979. (Data on coal qual- ity are generally deficient during 1977-1978, the early years of the formation of the U.S. Department of Energy. This becomes evident in the following discus- sion of coal quality.) Imports of western coal declined in the 1980s; and the average Btu/Ib of coal regained its pre-1970 level by 1990. The Btu content of coal is im- portant for two reasons. First, the higher Btu coals gen- erally contain less moisture and thus burn more effi- ciently; and second, the higher Btu coals reduce the total fuel costs because fewer tons of coal must be pur- chased and hauled. An important indicator of coal quality is its sulfur con- tent. Before the first clean air regulations were imple- mented in 1971, sulfur was not a factor that needed attention. Data on the average sulfur content of coal con- sumed in Illinois are available only since 1973, although there is still a gap for the year 1977 (fig. 8). The average sulfur content of coal consumed by electric utilities in Illinois fell from about 2.6% in 1973 to bet- ween 1.8% and 2.0% by the end of the 1970s and has since remained in that range despite the revision of the Clean Air Act in 1977. The 1977 revisions primarily af- fected power plants starting construction after Septem- ber 1978. Since then, only one coal-burning unit has become operational, and its construction began before the 1978 deadline, so it was not affected by the change in regulations. As a result, there was no significant change in the average sulfur content of coal used in Illi- nois in the 1980s. Some lowering of the average sulfur content of coal con- sumed in Illinois appears likely in the remainder of this century because of fuel switching by older plants. The million tons w o 24 1965 1970 1975 1980 1985 1990 Figure 6 Coal consumption by electric utilities in Illinois. 10.8 Btu/b (thousands) 10.1 1965 1970 1975 1980 1985 1990 Figure 7 Btu/lb of coal consumed in Illinois. 1979 Clean Air Regulations, based on the 1977 revision of the Clean Air Act, were favorable to burning the cheapest fuel, regardless of its sulfur content. This was made possible because regulations required all new plants to reduce their SO2 emissions potential by up to 90% as well as to meet the emissions limit of 1.2 Ibs SO? per million Btu consumed. Only "scrubbers" could meet both requirements. Consequently, all new plants built after 1978 had to have some type of scrubber, regardless of the sulfur content of coal used. The 1990 Clean Air Act amendments reverse this virtual require- ment and allow plants to meet the same stringent emis- sion limits by freely choosing between scrubbers, fuel switching, and emission allowance trading. If high sul- fur Illinois coal is economically competitive under the new circumstances, its use will increase. The record of % sulfur ine) ie) 1.8 1965 1970 1975 1980 3 1985 1990 Figure 8 Sulfur in coal consumed in Illinois. 10.6 10.4 10.2 10.0 9.8 9.6 9.4 9.2 9.0 8.8 8.6 8.4 8.2 1965 70 75 80 85 1990 % ash Figure 9 Ash in coal consumed in Illinois. the 1980s indicates that it is not easy to remain economi- cally competitive. Another environmentally significant trend with eco- nomic consequences is the amount of waste generated by electric power plants. Currently, only four major IIli- nois power plants have scrubbers, producing only small quantities of gypsum wastes; however, generation of gypsum or a similar product could substantially increase in the decades to come. Methods must be found to util- ize and/or dispose of these wastes, unless technologies such as the Integrated Gasification Combined Cycle (IGCC) become widely applicable. Similarly, electrostatic precipitators generate large quan- tities of fine ash that can be, and often are, used in QUANTITY AND QUALITY OF COAL CONSUMPTION cement production and other construction-related appli- cations. The generation of bottom ash depends primarily on the amount of "ash" or noncombustible material in coal. Data on ash content, like data on sulfur content, have only been available since 1973. The average ash content of coal consumed in Illinois’ electric utilities has declined from about 10.6% by weight in 1973 to about 8.6% in 1991 (fig. 9). Based on coal tonnage and the average ash content, it is estimated that bottom ash generation in Illinois has declined by about 33%, from 3.5 million tons in 1973 to 2.3 million tons in 1991. This trend is likely to continue as more sophisti- cated coal cleaning technologies are used, reducing the ash content of coal. Illinois is already at the forefront in the nation in terms of the percentage of coal being sub- jected to physical coal cleaning. More than 95% of IIli- nois coal is physically cleaned before sale, as compared with an average of about 60% to 65% for other states east of the Mississippi River. TRENDS IN COAL PRODUCTION TRENDS IN COAL PRODUCTION Subhash B. Bhagwat Illinois State Geological Survey More production data are available for coal than for any other mineral in Illinois. In this century, production of II- linois coal peaked at about 103 million tons in 1925. Af- ter the depression of the 1930s, production of Illinois coal rose again from about 34 million tons in 1932 to about 78 million tons during World War II. Production has fluctuated around the 60 million ton mark for the past 25 years, with the exception of a few years affected by miners’ strikes (fig. 10). Surface mining began in 1911 and peaked in 1967. The Surface Mining Act in 1971, which mandated reclama- tion of land after mining, and the depletion of surface minable reserves both contributed to a decline in surface mine production during the past two decades to about 16 million tons in 1991 or about 26% of total Illinois production. The decrease in surface mining and the corresponding increase in underground mining has the consequence that more coal is being left unmined to support the earth’s layers above underground mines. Modern room- and-pillar mines are designed to prevent subsidence by leaving about half of the coal in place for support. Most of these mines are expected to display no subsidence for many decades and maybe for centuries. The impact of subsidence depends on the magnitude, timing, and pat- 110 100 million tons 30 underground mined 1830 50 70 90 1910 30 50 70 1990 Figure 10 Trends in coal production in Illinois. 12 mines (thousands) 1890 1910 1930 1950 1970 1990 Figure 11 Number of mines in Illinois. 110 100 90 80 w» 70 fe § 60 =] £50 40 188290 1900 10 20 30 40 50 60 70 80 1990 Figure 12 Coal mining employment in Illinois. tern of surface sinking as a result of mining. In contrast to room-and-pillar mining, longwall mining is designed for quick and uniform subsidence over the entire panel mined. Subsidence of large, contiguous areas above longwall mining panels is less harmful to structures and more predictable than checkerboard patterns of subsi- dence caused by conventional room-and-pillar mining. As aresult, longwall mining methods have found in- creasing applications in Illinois coal mines. Longwall coal mining in Illinois started in 1977. In 1992, almost 27% of underground mining or 21% of all coal mining in Illinois was done by the longwall tech- nique. Eleven longwall units produced 12.7 million tons of coal in 1992. Longwall methods improve extraction United States Illinois a tons / person / day nN wo wo oa oO to oO 1955 60 65 70 75 80 85 1990 bh per 1000 employees ibe) wo = 0 1930 40 50 60 70 80 1990 Figure 14 Fatal coal mining accidents in Illinois. rates and reduce resource waste. At the same time, these methods also help improve productivity and reduce costs. The planned subsidence over longwall panels is a major safety and cost-saving feature in the long run. For example, a longwall machine shift produced nearly 2,400 tons in 1992, as compared with a conventional machine shift, which produced only 800 tons. The size of coal mines in Illinois grew in the past 35 years, while the number of mines declined (fig. 11). The largest increase in size occurred in the 1955-1965 period. Another significant increase in mine size took place in the past two decades. Mechanization and larger equipment sizes led to lower mine employment (fig. 12) and higher labor productivity (fig. 13). After World War TRENDS IN COAL PRODUCTION II, mine employment reached a low of 8,774 persons by 1962. From 1962 to 1972, production rose by 44% and employment rose by 42%. Labor productivity generally declined through most of the 1960s and 1970s because the number of person-days worked increased more rap- idly than the total production. A substantial increase in labor productivity, accompanied by a decline in employ- ment, followed in the 1980s and still continues. Employ- ment reached a low of 9,667 in 1991. A major factor behind lower employment and higher productivity is the continuation of the trend toward lower real coal prices since the mid-1970s. A point of concern to producers has been the loss of pro- ductivity advantage of Illinois mines vis-a-vis the U.S. average productivity. Illinois mines had a substantial ad- vantage in underground and surface mine productivity over the U.S. average in the 1960s. In 1991, however, the productivity of Illinois’ underground operations was the same as the U.S. average. The state’s surface mine productivity was only 55% of the U.S. average because U.S. surface mine productivity has increased rapidly since 1978, when large new mines opened in Wyoming and Montana. In these western states, thick coal seams and relatively thin overburden offer ideal surface min- ing conditions. Illinois coal mining has steadily improved safety in the past 60 years. Fatal accidents per 1,000 employees de- clined from about 2 in 1930 to about 0.3 in 1991 (fig. 14). The production pressure of the World War II years led to higher fatality rates. In some years such as 1951, major accidents disturbed the recognizable trend toward safer coal mines in Illinois. TRENDS IN OIL PRODUCTION AND CONSUMPTION TRENDS IN OIL PRODUCTION AND CONSUMPTION Subhash B. Bhagwat Illinois State Geological Survey Since the peak oil production of about 148 million bar- rels in 1940, the oil industry in Illinois has generally been on the decline. Primary production, using the natu- ral reservoir pressure for unaided flow of oil, declined consistently except in the early 1950s. Oil production rose in the 1950s as a result of secondary production methods—driving the oil out of reservoirs with water (fig. 15). But waterflooding could not stop the down- ward trend as oil fields were depleted. Unprecedented high oil prices in 1980-1981 gave the oil industry a strong incentive to boost production in the first half of the 1980s. Prices fell sharply in 1986 and have re- mained low since then. Total output by 1991 was about 19 million barrels. Between 1985 and 19839, the Illinois oil industry lost about 3,500 jobs, more than 50% of its total number of jobs. Most Illinois oil wells are economically marginal, pro- ducing less than 2 barrels of oil per day. Daily produc- tion per well in Illinoisfell from about 7 barrels in 1963 to 2 barrels in 1990. At this level of daily output, newly drilled wells would not be economical. By comparison, the U.S. average production per well in 1990 was about 12 barrels per day (fig. 16). U.S. daily production per well had been as high as 18 barrels in 1972 as a result of the large oil finds in Prudhoe Bay, Alaska. It has since fallen back to pre-1965 levels. million barrels primary recovery 0 1935 40 45 50 55 60 65 70 75 80 85 1990 Figure 15 Annual crude oil production in Illinois. United States 94750 55 60 65 70 75 80 85 1990 Figure 16 Oil production per well per day. Innovation and research in oil production technology are urgently needed because current practices leave about 60% of known oil in the ground. Reservoir hetero- geneity and other unfavorable geologic factors cause the loss of large quantities of oil reserves in the state at a time when more than 90% of the state’s oil needs have to be met by out-of-state or overseas sources. About 1960, when the brief surge in Illinois’ oil produc- tion was foundering, oil consumption in the state was rapidly rising (fig. 17), up nearly 70% in less than 20 years. A temporary drop in consumption was observed after the 1973-1974 oil price increase. Because of the lead time required to respond to higher oil prices, con- sumption of oil in Illinois continued to increase during 1976-1978, but was already on the decline when another oil price hike hit world markets in 1980 and 1981. Since 1982, oil consumption in Illinois has aver- aged about 225 million barrels per year, as compared with the 1978 high of about 335 million barrels. million barrels th oO oO 190 1960 65 70 75 80 85 1990 Figure 17 Oil consumption in Illinois. CO2 INJECTION FOR IMPROVED OIL RECOVERY Hannes E. Leetaru Illinois State Geological Survey A promising new trend in Illinois is the injection of CO2 into some of the more than 600 oil fields within the state. The procedure has two important benefits. First, it reduces CO? emissions, which may contribute to global warming. Second, it is also expected to increase oil pro- duction from Illinois reservoirs. Most of the 34,000 oil wells in the state are stripper wells that produce less than 2 barrels of oil per day and are close to their economic limit. In Illinois, more than 900 producing oil wells were abandoned and plugged in 1992 because they were no longer economical to op- erate. Since 1987, there has been a threefold increase in the plugging of producing oil wells (fig. 18). Also be- ing plugged at an increasing rate are water injection wells, which could be used for injecting CO? into oil fields. PRODUCTION AND SOURCES OF CARBON DIOXIDE IN ILLINOIS The total CO2 emitted in the state has been reduced from 280 million tons in 1970 to approximately 228 mil- lion tons in 1990. (All the reported CO2 emission data in this report are from Office of Research and Planning, Illinois Department of Energy and Natural Resources, and should be considered as preliminary estimates.) The two most likely sources of CO2 for subsurface injection are utilities and industries. Utilities emit approximately 120 oil 100 80 60 wells per year 1987 1988 1989 1990 1991 1992 Figure 18 Oil production and water injection wells plugged in Illinois. (Data courtesy of Illinois Department of Mines and Minerals Oil and Gas Division.) COz INJECTION FOR IMPROVED OIL RECOVERY 63.3 million tons of CO2 during the generation of elec- tricity; however, the CO2 must be purified by separating it from the rest of the power plant stack gas. Industrial plants emit another 51.2 million tons of CO2. The oil industry is already experimenting with CO2, formed as a byproduct of the manufacture of ethanol, to enhance oil production in the Illinois Basin. A major ethanol producer is located in Decatur, Illinois, which is within a 100 mile radius of many of the state’s oil fields. Currently, the CO2 from ethanol is being transported to the oil fields by refrigerated tank truck, a mode of trans- port that is not cost effective for injection of large vol- umes of gas. An alternative is to construct gas pipelines, although this method may not be economical either, given today’s low oil prices. APPLICATION OF CO2 INJECTION INTO OIL FIELDS Three significant applications of CO2 in improved oil recovery in Illinois are miscible and immiscible floods and "huff and puff" (cyclic flood process). CO2 injec- tion is relatively new in Illinois, so not much data is available. In other parts of the country, huff and puff projects have been economical at current oil prices (Stewart-Gordon 1990). CO2 miscible-immiscible flood- ing, usually considered uneconomical at less than $30 per barrel of oil (Petzet 1983), could become important if oil prices rise significantly. Miscible and Immiscible Flood Waterflooding has been the most widely used method of increasing oil recovery from older oil fields in Illinois. Because an oil field is rarely a single, continuous reser- voir (reservoir heterogeneity), millions of barrels of oil in the reservoir are bypassed by the injected water. Also, the injected water cannot mobilize an equal or greater volume of oil, which is trapped in the pore space by vis- cous and capillary forces. CO? flooding, in addition to recovering some bypassed oil, can also recover some im- mobile oil trapped in the pore space. Approximately 4.4 billion barrels of residual oil may still be recoverable in Illinois oil fields (U.S. Depart- ment of Energy 1989). Some of this oil should be re- coverable by miscible and immiscible CO2 flooding. During a miscible flood, the CO2 is injected into the reservoir at a high enough pressure that the CO2 and oil dissolve into one another; the capillary force is drasti- cally reduced, and the oil and the CO? act as a solvent 15 CO2 INJECTION FOR IMPROVED OIL RECOVERY and flush the oil from the reservoir. In general, oil reser- voirs that have depths greater than 2,500 feet and con- tain oils with an API gravity of 25° or greater are potential targets for CO2 miscible flooding (Venuto 1989). More than 270 oil fields in Illinois meet this requirement (B.G. Huff, ISGS, personal communication 1993). CO? is preferred over other solvents such as natural gas or nitrogen because CO2 needs a much lower pressure to become miscible. In a reservoir in which the CO2 mis- cible pressure is 1200 psig, the natural gas pressure re- quired for mixing would be more than 5000 psig (Stalkup 1989). The higher pressure of the natural gas would fracture the reservoir and make miscible flooding impossible. Pure CO2 must be used, however, because impurities such as nitrogen could raise the required mis- cible pressure to more than 2000 psig (Stalkup 1989).Thousands of tons of CO? are injected into the oil field during a miscible flood. In a large, 100 million bar- rel oil field, the requirement could be as high as 1 bil- lion tons of CO2 in a5 to 10 year period (Stalkup 1989). Much of this injected CO2 remains in the reservoir after completion of the flood. The actual amount of CO? re- tained depends on whether or not produced COz is recy- cled back into the reservoir. A CO? immiscible flood should be more efficient than a waterflood, although not as efficient as a miscible flood (Holm 1987). The difference between immiscible and miscible is that in a miscible flood, the CO2 behaves as a solvent decreasing the capillary force that retains the oil in the reservoir rock. In an immiscible flood, the injected CO? causes swelling of the oil and reduces its viscosity, both of which make the oil flow more easily to the surface (Holm 1987). The cost and risk of this type of flooding is intermediate between miscible flood- ing and huff and puff. Immiscible CO2 flooding is technically feasible in many Illinois Basin oil fields; however, the economics are uncertain. Huff and Puff Huff and puff may be the final attempt to get more oil from a well before it is abandoned (Stewart-Gordon 1990). The technique has been economical at the 1990 oil prices because each ton of carbon dioxide can add be- tween 15 to 20 barrels of incremental oil (Miller 1990). In huff and puff (cyclic CO2 injection), the CO2 is in- jected into a well at immiscible conditions; 2 to 4 weeks after the injection, the same well is put on production. The average estimated radius of CO2 migration has been 73 feet for the most productive wells, and 144 feet for the poorer wells (Thomas and Monger 1990). 16 The amount of CO2 injection depends upon field condi- tions. The minimum amount is usually 20 tons, and many huff and puff projects have used 120 to 4,000 tons of CO2. Some major injection projects have recovered as much as 9,000 barrels of incremental oil per well (Stewart-Gordon 1990). Results of more than 200 appli- cations of huff and puff (Haskin and Alston 1989, Miller 1990) show an average incremental oil recovery of 400 barrels for a 20 ton CO2 project. A 120 ton CO2 huff and puff will recover 1,000 to almost 4,000 barrels of incremental oil. Approximately 40% to 50% of the in- jected CO? remains in the oil reservoir after a huff and puff program. Only 10% of these projects did not suc- ceed in increasing the oil recovery, and most of these failures were due to mechanical problems during the in- jection process (Thomas and Monger 1990). CONCLUSIONS Of the three different types of CO2 injection projects, miscible flooding can be the most efficient for recover- ing additional hydrocarbons. Because it is also the most expensive and difficult to accomplish, it is best suited for large projects. Immiscible flooding is less costly be- cause the injection pressures do not have to be as high. It is necessary to completely understand reservoir conti- nuity, however, to have a successful flood using this method. Huff and puff is the least efficient in recovering additional reserves because only a small portion of the reservoir is contacted by CO2. It is suitable for small projects because of its low cost and low risk. In 1992, 941 oil wells were plugged. Many could be candidates for the huff and puff technique, but technical data are insufficient to indicate how many wells would react favorably to huff and puff. But assuming that huff and puff could be successfully applied to 800 plugged wells, and further assuming an average 20 ton CO2 in- jection and a 50% recovery of the CO2 per well, there could be an 8,000 ton reduction of CO2 emissions per year and an annual increase in oil production of 320,000 barrels. In a more optimistic case of 120 tons of COz in- jection and recovery of 2,000 barrels of oil per well, the CO? emissions would be decreased by 48,000 tons and oil production increased by 1.6 million barrels. The CO? injection technology is a promising new trend that could reduce CO2 emissions and increase oil recov- ery within Illinois. The mechanism for supplying CO2 from the manufacture of ethanol is already in place and could be the most viable near-term source for this gas. TRENDS IN NATURAL GAS PRODUCTION AND CONSUMPTION Subhash B. Bhagwat Illinois State Geological Survey Natural gas is the cleanest-burning fossil fuel. But IIli- nois has only insignificant known reserves. Natural gas may be found at depths greater than the depth at which natural gas is currently produced in Illinois. The geology at 5,000 feet and deeper below land surface has not been explored well enough for a sound assessment of the po- tential for reserves of natural gas. Lacking reserves at shallow depths, Illinois has pro- duced little natural gas — an average of less than 1.5 bil- lion cubic feet per year in the 1980s. During the same period, consumption of natural gas in Illinois, although declining slightly, averaged about 1.0 trillion cubic feet per year. The decade of the 1960s was the last to show an increase in gas consumption, which grew from about 0.5 to 1.2 trillion cubic feet, a rate of more than 8% per year (fig. 19). Since the 1971 peak, consumption has gradually declined as a result of energy-saving measures by consumers in response to price increases. End uses of natural gas have also changed in the past quarter century (fig. 19). Consumption reached its peak in the electrical sector in 1970 and in the industrial sec- tor in 1971, partly as a result of low, regulated prices. Price regulation was introduced in 1954 as a result of a Supreme Court verdict in the case of Phillips Petroleum electric utilities and other industrial trillion cubic feet residential 1955 60 65 70 75 80 85 1990 Figure 19 Consumption of natural gas in Illinois. TRENDS IN NATURAL GAS PRODUCTION AND CONSUMPTION versus Wisconsin. The court interpreted the 1938 Natu- ral Gas Act (NGA) to require regulation of wellhead prices for interstate markets, so the producer would be protected. By 1970, however, regulated prices began to lag behind market prices. Most of Illinois’ supply of natural gas was purchased in the interstate market. Thus, lower prices were an incentive to use gas in industrial production as well as in electricity generation. In 1978, the Natural Gas Policy Act (NGPA) was en- acted in response to fuel shortages in the interstate mar- ket. The NGPA divided gas into categories according to the date of gas discovery and depth of gas deposits. At the same time, the Fuel Use Act of 1978 (FUA) re- stricted the use of natural gas in electricity generation. Gas shortages and concerns about supply reliability in the early 1970s had already reduced its use in electricity generation. Price increases of 1973-1974, supported later by the production incentives of NGPA and the de- mand restrictions of the FUA, further contributed to de- clining gas consumption. Another international oil price increase in 1979-1980 added an incentive to reduce con- sumption. Continuing the trend, industrial consumers contributed most to the reduction in consumption in the 1980s, although savings were also achieved in the com- mercial and residential sectors. The NGPA also provided for gradual decontrol, begin- ning in 1985, of wellhead gas prices. The Federal En- ergy Regulatory Commission (FERC) changed the gas market radically in the latter half of the 1980s. FERC orders 486 and 500 made it possible for interstate pipe- lines to act as "open access transporters" of gas pur- chased directly from the producer. Order 451 permitted the price of the oldest (lowest priced) gas to increase, and order 490 permitted abandonment of old purchase contracts (signed under NGA) when they expired. So in the 1980s, the gas market became a free market, which contributed to greater availability and lower prices. In 1989, prices were entirely freed from controls under the Natural Gas Wellhead Decontrol Act of 1989. The ex- cess of gas supply (bubble) over demand created by the increasing supply and falling demand was nearly gone by the end of the 1980s and early 1990s. Conditions fa- vored greater price stability and even some increases. Demand in the 1990s is expected to be influenced by two opposing factors. Energy conservation in all three major consuming sectors — residential, industrial, and commer- cial — will continue to exert a downward pressure on de- mand. Conversely, economic growth rates may fluctuate. Demand may not only grow slowly in the 1990s, but also show periodic ups and downs. UNDERGROUND STORAGE OF NATURAL GAS UNDERGROUND STORAGE OF NATURAL GAS C. Pius Weibel Illinois State Geological Survey Natural gas is stored in underground reservoirs so that adequate supplies of fuel are available when consump- tion is greater than wellhead production. During sum- mer months, demand is lower and the stockpile is built up. During the winter when consumption is high, gas is withdrawn from the stockpile to meet consumer demand. Large quantities of natural gas are stored in depleted petroleum reservoirs and in aquifers that do not supply water suitable for drinking. In the United States, most of he gas is stored in depleted gas reservoirs (Bond 1975). In Illinois, however, more than one-half of the storage fields, representing more than 90% of the storage by vol- ume, are nonpotable (saline) aquifers (Buschbach and Bond 1974). SOURCE OF DATA The Illinois State Geological Survey (ISGS) began to gather and publish data on underground storage of natu- ral gas in Illinois in 1961 (Bell 1961). The annual re- ports on the petroleum industry in Illinois (ISGS Illinois Petroleum series) included natural gas storage data up to 1981. For the next 5 years, the data were published with- out revision. In 1986, publication of the database ceased. An attempt was made in 1986 to obtain updated statistics, but only a few companies responded (B.G. Huff, ISGS, personal communication 1993). The overall quality of the database on underground gas storage fields is inadequate. The initial data published in 1961 (Bell 1961) consisted only of the volumes of cush- ion gas and working gas capacity for each storage area. Later reports were more detailed and included opera- tional history, number and type of wells, geological data, reservoir data, and yearly withdrawal volumes. Al- though yearly revisions were made through 1981, the data provided by gas storage field operators were nei- ther consistent in quality nor regularly updated. Some re- vised data were obtained in 1986, but most data are 10 or more years out-of-date. Currently, the number of un- derground natural gas storage fields in Illinois is esti- mated to be 34. 18 The ISGS has also published several reports on the geology of individual storage fields (Bell 1961, Bond 1975, Buschbach and Bond 1967, 1974). PAST TRENDS The first successful attempt to store natural gas under- ground in Illinois occurred in 1951 at the depleted Waterloo oil field. Most natural gas storage areas were established during the late 1950s to the mid-1970s. Natural gas has been stored in rocks ranging in age from Cambrian to Pennsylvanian (about 600 to 225 million years old). Sandstone is the most common reservoir rock used for gas storage, although limestone and dolo- mite are used in a few storage fields. Past trends in the siting of underground natural gas stor- age facilities are derived by considering the storage site location, type of storage reservoir, time of site develop- ment, and geologic age of reservoir rock. A major factor in the siting of storage fields in the past was access to preexisting pipelines that transport gas to major consum- ers. There is no discernable past connection between the time of site development and either storage type or geo- logic age of the reservoir rock. Most natural gas has been stored in rocks of Cambrian and Ordovician age. In the northern half of the state, gas is mostly stored in the Cambrian Mt. Simon and Gales- ville Sandstones. The Ordovician St. Peter Sandstone is utilized in southwest Illinois. In the southern half of the state, Mississippian strata are the most common storage reservoirs. Gas is stored in Silurian, Devonian, and Pen- nsylvanian rocks in scattered areas throughout the cen- ter of the state. The regional geology of the state is an important con- tributing factor in selection of the type of reservoir and field size most suitable for gas storage. Figure 20 de- picts a map of Illinois divided into sectors. About one- half of the storage fields are in sector A and one-half in sector B. Natural gas storage fields in sector A occur only in nonpotable aquifers. This area contains few oil fields and oil production is from relatively shallow depths. Natural gas is stored in rocks deeper than either petroleum-producing horizons or freshwater aquifers. The storage fields in sector A are all large (10,000 MMcf potential capacity), except for the Pecatonica field. Depleted oil and/or gas fields provide most of the stor- age in sector B. Plenty of depleted fields are available for gas storage because this area contains most of the pS La] - _ t= | eat a Ee fete R | ve a ee ee i ee L ae fis Figure 20 Map showing location of underground natural gas storage sites. Sector boundaries are based on differences in regional geology. petroleum-producing fields in the state. Nonpotable aquifers in Cambrian and Ordovician rocks, the most common reservoirs in sector A, are significantly deeper in this sector, so they are more expensive to develop. Most storage reservoirs in sector B are in rocks younger than Silurian (less than 400 million years old). Also, most of the current storage fields are small. The Louden oil field is the only large natural gas storage field in this sector. Two economic factors, price and demand, may have had an effect on the apparent suspension of developing natu- ral gas storage fields. Natural gas prices began to in- crease in the middle 1970s, and demand subsequently began to decrease (S.B. Bhagwat, ISGS, personal com- munication 1993). The peak in natural gas consumption in Illinois coincides with the apparent halt in storage area development (fig. 21). Decreasing demand coupled with the increasing expense of maintaining cushion gas may have contributed to the halt in storage area develop- ment. It is also possible that pipeline companies had developed enough storage areas to handle consumer demand. UNDERGROUND STORAGE OF NATURAL GAS MCF MCF x1000 x1000 140,000 10,000 = 120,000 g 400,000 § = ® 6 =) = 80,000 © 2 3 = ” 2 60,000 re [o} Dm oO = 2 © D P=} =. 40,000 © =! ne] - = 2 3 D s ic 20,000,550 60 70 80 1990° = Figure 21 Chart depicting natural gas consumption and underground natural gas storage capacity in Illinois. During the mid-1980s, consumers began to purchase natural gas directly from producers and use pipeline companies only for transporting gas. Thus, pipeline companies are increasingly becoming service opera- tions. They are under the obligation to deliver adequate quantities of gas when needed but must compete with rival pipelines. So they are likely to be cautious about expanding and developing storage facilities. Also, stor- age facilities may possibly become independent busi- nesses in the future. ENVIRONMENTAL IMPLICATIONS Construction and operation of underground natural gas storage fields in the United States are regulated by the Federal Power Commission (Code of Federal Regula- tions 1973). The Illinois Commerce Commission also regulates facilities in Illinois. In addition, permits to drill exploration and injection wells must be obtained from the Illinois Department of Mines and Minerals. A storage company may also have to give the Illinois Envi- ronmental Protection Agency and the Illinois Depart- ment of Mines and Minerals an environmental impact statement on potable aquifers on the proposed site. State regulations do not permit the development of stor- age facilities in potable aquifers, although probably all storage sites occur underneath aquifers that yield water for drinking, irrigating, and related purposes. Pollution of these aquifers by gas leaking from the underlying storage can be a problem (Coleman et al. 1977). In the Manlove storage field in west-central Champaign County, natural gas was stored initially in St. Peter Sand- 19 UNDERGROUND STORAGE OF NATURAL GAS stone. Soon after injection, gas was discovered to be mi- grating from the St. Peter up into overlying, glacial sand and gravel aquifers. Tests showed that the deeper Mt. Si- mon Sandstone had an impermeable cap that would seal in gas. It was subsequently used as the storage reservoir. Aquifer pollution by leaking natural gas does not always make the water toxic to humans. But when gas displaces water in an aquifer, it may mean that the aqui- fer is no longer useful as a water source (Bays 1964). Because the gas is not under pressure, the concentration remains low in most cases. But a major leak could re- sult in an explosion, causing damage to structures and injuries to the occupants. If gas is leaking from an un- derground storage facility, it may have to be aban- doned. When a depleted petroleum field is developed into a natural gas storage field, the impact on the environment is likely to be minimal. Fewer wells have to be drilled and access roads to wellheads are already available. By contrast, using nonpotable aquifers for gas storage in- volves greater start-up costs: more exploratory wells have to be drilled and access roads have to be built to each wellhead. Using depleted petroleum fields also has some drawbacks. Abandoned oil wells that have not been adequately plugged can leak natural gas or pollute potable groundwater. Conflicts can arise between pro- ducers extracting petroleum from one part of a field and companies storing natural gas in another part. FUTURE TRENDS Nonpotable aquifers in Cambrian and Ordovician are the most suitable for underground storage of natural gas because they have the largest storage capacities. Future exploration for such sites will continue in sector A (fig. 20). Large gas storage facilities are also likely to be developed in sector B3 within the La Salle Anticli- norium and near the edges of sector B2, where several large anticlinal petroleum fields occur. As large ade- quate structures become difficult to find, exploration for sites in Cambrian and Ordovician rocks may move to sectors B1 and B3, where these rocks are deeper but have been used for gas storage in a few fields in the past. Cambrian and Ordovician rocks in sectors B2 and C are significantly deeper than in other parts of the state, so they are not likely to be targets for gas storage Sites. The ongoing gradual depletion of petroleum reservoirs will provide sites that have potential for gas storage. 20 Depleted petroleum reservoirs have the additional ad- vantage of being "tested by nature." Most of these facili- ties will be in sector B. Smaller gas storage facilities may become more com- mon in the future as the number of potentially large stor- age sites decreases. Many small petroleum reservoirs occur in sector B, which is well served by gas pipelines. In fact, the gas pipeline system in the state is so exten- sive that there are few geographic restrictions to storage sites. In the deeper parts of the Illinois Basin (sectors B and C), storage sites may be developed in nonpotable aquifers beneath depleted petroleum fields or beneath preexisting gas storage facilities. Sector C, the most structurally complex area in the state, will be the most difficult to explore for suitable gas storage sites. STONE, SAND AND GRAVEL INDUSTRY Subhash B. Bhagwat Illinois State Geological Survey Critical to the infrastructure and economy of Illinois is the stone, sand and gravel industry, also called the aggre- gates industry. In terms of the dollar value, the produc- tion of aggregates currently ranks second only to the production of coal in Illinois. In the past, the oil indus- try in Illinois has often surpassed the aggregates indus- try in dollar value because of the high price of oil, especially during 1979-1985 and before the early 1960s. Roads, bridges, railroads, waterways, airlines, water and electricity supply lines, sewer systems, and telecommu- nications make up the state’s "physical" infrastructure. The development and maintenance of this infrastructure as well as the construction of commercial, industrial, and residential structures depends greatly on the avail- ability of aggregate resources. In the absence of local sand and gravel and stone resources, Illinois would have to spend another $1 billion or more per year to import aggregates from other states. The price of aggregates, low unit-value products, is sensitive to the cost of trans- portation, which can triple the price of a shipment to a customer 50 miles away from the source. Since 1950, the production of aggregates has almost tri- pled from about 34 million to 100 million tons in 1990. The trend has been toward greater use of stone than of 70 aS Oo w Oo million tons sand and gravel 20 0 _ ——— 1950 55 60 655 70 75 80 85 1990 Figure 22 Illinois stone , sand and gravel production. STONE, SAND AND GRAVEL INDUSTRY sand and gravel (fig. 22). Stone production grew more rapidly from 1950 to 1973 than did sand and gravel pro- duction, primarily because the size and shape of stone make it more suitable than sand and gravel for the pro- duction of concrete. (Stone can be crushed easily to any size, and crushing creates sharp, angular particles in con- trast to the rounded particles of sand and gravel.) The 1973-1983 period was marked by a decline in stone as well as in sand and gravel production. Economic re- cessions experienced by the United States in 1975 and 1982 were triggered by bouts of inflation in 1973-1974 and 1979-1981. The resulting decline in construction activities was interrupted only by 2 years of relative growth in 1978-1979. Since 1983, the growth in sand and gravel and stone production has not lost its momen- tum. Once again, stone production is outperforming sand and gravel production in Illinois. An important growth factor for the stone industry is the use of the carbonate materials, limestone and dolomite, for pollution control. Limestone can be directly used for this purpose or first converted to lime. Four coal-burn- ing utilities in Illinois currently use limestone or sodium carbonate to remove SO? from flue gases. Their lime- stone consumption is estimated to be about 300,000 tons per year. (Historical data are not available.) Lime also has other industrial and agricultural uses. The de- mand for lime and limestone is small in comparison with the total demand for crushed stone. Quicklime and hydrated lime, other derivative stone products, are used primarily in the steel industry. Figure 23 shows Illinois’ consumption for the past 35 years. It reached a peak of about 1.2 million tons in 1974, but has historically fluctuated between 0.6 and 1.2 million tons. A major decline in consumption to a 25-year low point occurred between 1978 and 1982 as a result of the declining usage in the steel industry and the 1982 gen- eral recession. From 1982-1990, consumption picked up again, increasing by about one-third or at an annual rate of about 4%. Most increases since 1987 have occurred because of increased use by chemical firms and munici- pal water-treatment plants. Intensely competitive markets, in which real dollar prices per ton of the commodity did not change appre- ciably over the past two decades have forced sand and gravel and stone producers to take cost-cutting mea- sures. Economies of scale have improved productivity. Production from large mines as a percentage of total pro- duction has increased significantly since the early 21 STONE, SAND AND GRAVEL INDUSTRY hydrated lime million tons quicklime 1955 60 65 70 75 80 85 1990 Figure 23 Illinois quicklime and hydrated lime consumption 1980s. In 1982, about 32% of Illinois’ sand and gravel came from operations producing more than 800,000 tons per year; the largest pit produced a little less than 900,000 tons per year. In 1990, nine pits in Illinois were each producing more than 1 million tons, and they ac- counted for about 49% of the state’s production. Between 1982 and 1990, as smaller operations closed or consolidated, the number of sand and gravel pits de- clined in Illinois from 169 to 143. A similar trend toward larger operations was also observed in the stone industry, although the number of operations actually increased from 169 in 1983 to 178 in 1989. In 1983, about 36% of the state’s stone was produced in quarries with a capacity to deliver more than 900,000 tons per year. Their share increased to 58% in 1989. Urban expansion, engulfing pits and quarries, has con- tributed to the trend toward fewer, but larger production units. As demand continues to rise, the production of smaller pits overrun by urban sprawl! must be taken over by other pits. The result is expansion of the remaining pits. One benefit is that the closed pits and quarries will, in many cases, be made into ponds and lakes that are managed and used in environmentally acceptable ways. Some sites may play an important role in the creation of wetland habitats. Many of the most important known deposits of aggre- gate materials are in northeastern Illinois, which is undergoing rapid urban development. Urban and envi- ronmental planning must be combined with comprehen- 22 sive resource exploration to ensure wise and sustained utilization of Illinois’ aggregate resources. ISGS scientists doing field work indicate that a signifi- cant number of operations may be going unaccounted for because of seasonal or short-term operation and/or a lack of response to data solicitation by the U.S. Bureau of Mines (USBM). Producers’ rights to proprietary pro- duction information are protected under Public Law 96- 479, the National Materials and Minerals Policy Act of 1980. Producers exercise that right and require that pro- duction data not be published for geographic areas smaller than the four zones in Illinois, as agreed upon by the producers, the USBM, and the ISGS. The future prospects of the aggregates industry will be determined by several factors: 1. Total demand will be determined by economic growth in general and growth in the construction indus- try in particular. Federal and state government priorities for rebuilding of the infrastructure may significantly in- crease and focus demand. 2. Availability of and access to sand and gravel and stone resources may be increasingly limited in the future as urban expansion renders reserves unminable. Examples of such cases are known in the Chicago area. Operators are being forced to resort to underground mining, where possible, or to relocate to remote sites. The more remote the source, the greater the transporta- tion costs. 3. Quality specifications for aggregates have changed during the past two decades. As a result, markets are less favorable for sand and gravel than for stone. The shift in demand could further strain the stone supply. OTHER MINERALS PRODUCED IN ILLINOIS Subhash B. Bhagwat Illinois State Geological Survey Industrial sands, clays, fluorspar, tripoli, zinc, lead, sil- ver, copper, peat and some gemstones have historically been produced in Illinois, although in smaller quantities than coal, oil, and construction aggregates. Data on pro- duction of these other minerals are mostly proprietary, but the production data on industrial sands and clays are available for publication. Illinois ranks first among states producing industrial sands in the United States. From the end of World War II to the early 1960s, the state’s production of industrial sands averaged about 3 million tons per year (fig. 24). Production rose significantly during the later part of the 1960s, fluctuated greatly in the 1970s, and averaged about 4.5 million tons per year since then. Industrial sands, now produced only in La Salle County, have a wide variety of applications. Unground silica sand is used primarily in manufacturing glass, but also for pro- ducing industrial molds, and sand blasting, grinding, and polishing various materials. Railroad traction and filtration are two other uses for unground sand, which is also suitable for propping open the fractures formed when oil reservoir rocks are hydraulically fractured to stimulate oil production. Ground sand is used in chemi- million tons wo oS oa Le) 1945 50 55 60 65 70 75 80 85 1990 Figure 24 Industrial sand production in Illinois. OTHER MINERALS PRODUCED IN ILLINOIS common clay million tons _ np 1955 60 65 70 75 80 85 1990 Figure 25 Common clay production in Illinois. cals, abrasives, enamels, pottery, porcelain, tile, and as various fillers. High purity silica sands are the basic raw material in many high technology applications, such as computer chips and electronic circuits. The industrial sands of Illinois are important raw materi- als mined in an area that is advantageously located near Chicago and served by an excellent network of roads and waterways. In contrast to the industrial sand industry, Illinois’ clay industry has suffered from market competition in the past 25 years. Common and refractory clay production averaged about 2 million tons per year from 1955 to 1965 but declined to about 0.2 million tons by 1989 (fig. 25). Production of refractory clays has all but ceased. The decline is largely due to intense competition from clays and clay products such as bricks produced in Georgia, Alabama, Texas, and North Carolina and shipped at favorable freight rates on trains returning to Illinois after delivering grain to the Gulf Coast. Contrib- uting factors are changes in demand pattern and poor management by small operators. Illinois has always been a major producer of fluorspar. During the past two decades, Illinois remained the nation’s number-one fluorspar producer. Production data are confidential, however, because only one major fluorspar producer has remained in the business. Cur- rently, more than 90% of U.S. fluorspar is produced in Illinois. 23 RECLAMATION OF ABANDONED MINED LAND RECLAMATION OF ABANDONED MINED LAND C. Pius Weibel Illinois State Geological Survey Extraction of mineral and nonmineral resources from the earth by surface and underground mining has had a significant impact on the natural environment of the affected areas. The impact of the modified land on both the economic and social environments of the area is gen- erally negative. Unreclaimed mined lands often result in altered land use patterns, erosion, water pollution (acid runoff), siltation, and landslides (Roberts 1979). To avoid these problems and restore the natural, economic, and social environ- ments to the affected lands of Illinois, the State estab- lished reclamation practices. Reclamation is the restoration of the land surface previously affected by surface and underground mining to the condition of opti- mum productive use for the future. Productive use of land includes the establishment of forests, pastures, and crop lands; enhancement of wildlife and aquatic resour- ces; establishment of recreational, residential, and indus- trial sites; and conservation, development, management, and appropriate use of natural resources for compatible multiple purposes (Surface Mined Land Conservation and Reclamation Act 1971). Federal and state legisla- tures have passed laws regulating both mining and recla- mation procedures. DATA The Illinois Department of Mines and Minerals (IDMM) is responsible for collecting data on the recla- mation efforts of the mining industry in Illinois. The IDMM publishes an annual report, which includes lists of the acres mined in the state, number of mining per- mits issued, and number of acres affected by reclama- tion. Reclamation of land mined and abandoned before laws required reclamation are not in the IDMM annual report. The "pre-law" lands are reclaimed under the aus- pices of the Abandoned Mined Land Reclamation Coun- cil (AMLRC). The AMLRC maintains an inventory of reclaimed and remaining abandoned mine problem sites within the state. 24 A compilation of the acreage affected by coal mining was first published in 1963, and collection of data for surface mining of minerals other than coal started in 1972 (IDMM 1992). During the late 1970s, the methods of gathering and cataloging data were reorganized, re- sulting in inaccuracies (generally due to undercalcula- tion) in the acreage affected by surface mining (S.B. Bhagwat, ISGS, personal communication 1993), PAST TRENDS In Illinois, the first regulatory bill involving reclamation of surface mines was introduced and defeated in the leg- islature in 1929. Other attempts to pass similar bills were defeated until the Open Cut Land Reclamation Act, which took effect on January 1, 1962 (Klimstra and Jewell 1974). This act required that spoil ridge tops on all open pit mines be leveled, graded, and revegetated. In 1968, requirements for reclamation were increased by the Surface Mined Land Reclamation Act. The Sur- face Mined Land Conservation and Reclamation Act (SMLCRA) was passed by the Illinois Legislature in 1971 and subsequently amended periodically. The SMLCRA specifically required filing a conservation and reclamation plan before the start of mining. It also contains reclamation regulations associated with the sur- face mining of sand and gravel, limestone, silica, and clay/shale. Mine sites where the overburden is less than 10 feet thick, or operations that affect less than 10 acres during the state’s fiscal year, are exempt from the act. Operators of such sites do not have to apply for surface mining permits. The Illinois Abandoned Mined Lands Reclamation Council (AMLRC) was first established in 1975 to re- claim coal mine sites abandoned prior to implementa- tion of federal coal mine reclamation regulations. Initial funding was provided by General Assembly appropria- tions. In 1977, the federal Surface Mining Control and Reclamation Act (SMCRA) was passed, requiring all states to develop regulatory programs that, at a mini- mum, met the requirements of the federal regulations. This law, unlike previous Illinois reclamation bills, regu- lated only coal mines. Section 402 of the act established a fund for use in reclaiming coal mines abandoned prior to enactment of the bill. (Mining companies were charged fees of $0.35 per ton of surface-mined coal, $0.15 per ton of underground-mined coal, and $0.10 per ton of lignite.) To be eligible to receive the federal aban- doned mine reclamation grants, states were required to regulate active coal mining. RECLAMATION OF ABANDONED MINED LAND / total production acres affected by surface mining surface mine production acres reclaimed by AMLRC coal production (x100,000 tons) / acreage (x10) 1965 75 85 1991 Figure 26 Coal production versus reclamation. In 1980, Illinois passed the Surface Coal Mining Land Conservation and Reclamation Act (SCMLCRA), which enabled the state to enforce the permanent regula- tory program under the federal SMCRA. Also in 1980, the State amended the Abandoned Mined Lands and Water Reclamation Act, which established the AMLRC as the agency to administer the federal reclamation funds in Illinois. In 1989, this act was amended to in- clude the reclamation of unreclaimed noncoal sites that contain safety hazards; however, Illinois law restricts the amount of money that can be spent annually on rec- lamation of noncoal sites. Reclamation of lands affected by mining generally is classified into three categories: 1. "Pre-law" coal refers to land mined and abandoned prior to passing the 1977 federal reclamation act. This acreage is eligible for reclamation by the AMLRC. 2. ""Post-law" coal refers to land mined after the law was passed. Affected acreage has to be reclaimed by the mine operators. 3. Noncoal refers to other surface mine operations, gen- erally involving the extraction of clay/shale, fluorspar, limestone, industrial sand, and gravel. Most acreage affected by mining in Illinois is from surface coal mining, which since 1963, has affected slightly more than 3,000 to more than 7,000 acres annually (fig. 26). The amount of affected acre- age peaked during the late 1960s, then declined at a rate of about 375 acres annually. The decline parallels a gradual decrease in production of coal produced from surface mines together with an increase in production pasture 74.9% crop 13.9% miscellaneous 5.9% industry 0.3% recreation/wildlife 1.5% forest 3.5% Figure 27 Land use of reclaimed coal surface mines (1972-1985). from underground mines (fig. 26). Since the SMLCRA was enacted, reclaimed coal surface mine acreage has been dominated by pasture and crop lands (fig. 27) be- cause these types of reclaimed acreage were the main fo- cus of the regulations. In the late 1970s, the AMLRC began to reclaim lands affected by "pre-law" coal mining (fig. 26). Since the early 1980s, the Council has reclaimed annually about 500 to 1,000 acres, and over- all, a total of 8,582 acres of land affected by coal mining (Nutt 1992). Most of the acreage reclaimed by the AMLRC was mined for coal; but recent amendments to the Abandoned Mined Lands and Water Reclamation Act allow the Council to reclaim previously abandoned noncoal mine sites for a period of 5 years, starting in 1989 (St. Aubin 1990). The SMCRA stipulates that these abandoned mine sites, although unrelated to coal mining, may be reclaimed by the Council, if the site is considered to be an extreme danger to the public. The amount of acreage reclaimed from noncoal surface mining since 1972 peaked in the early 1980s at about 800 acres, although the aforementioned reorganization of the database may have influenced this datum (fig. 28). The acreage amount gradually declined until recently. Most of the reclaimed land has been used either as pasture or for industrial and commercial sites (fig. 29). Very little has been reclaimed as crop land, but there is no crop land reclamation requirement for non- coal mines. Most noncoal mine sites only affected small plots, relative to the size of coal mine lands. Many of these sites are near established towns, and smaller plots are more attractive for industrial and commercial devel- opment than for agricultural use. 25 RECLAMATION OF ABANDONED MINED LAND 1,000 800 600 forest/wildlife acres 1972 75 80 85 7990 Figure 28 Use of reclaimed acreage from noncoal mines. ENVIRONMENTAL IMPLICATIONS The elimination of public health, safety, and environ- mental problems at abandoned mine sites is the primary focus of the Illinois abandoned mine reclamation pro- gram. The ultimate goal is the restoration of the natural environment of an abandoned mine site. Reclamation of abandoned mines offers many benefits (from Croke and others 1979): 1. Protection of public health and safety by eliminating hazards such as open mine shafts, unsafe dams, leaking methane, coal refuse fires, and dangers associated with mine subsidence. 2. Aesthetic improvement of landscapes and develop- ment of recreational areas. 3. Decrease in erosion, downstream siltation, and restoration of stream beds. 4. Elimination of sources of acid run-off to surface and groundwater resources. 5. Restoration of vegetative cover for wildlife habitats, erosion control, and agricultural or conservation pur- poses. 6. Stimulation of the local economy through jobs re- lated to construction, conservation, and recreation as land is restored to useful condition. 26 pasture 38.4% crop 1.8% miscellaneous 24.0% water 4.0% forest/wildlife 0.4% Figure 29 Use of reclaimed acreage from noncoal mines (1972-1991). FUTURE TRENDS AND IMPACTS As long as the current mining and reclamation laws continue to be renewed and enforced, the trends of recla- mation during the past 10 to 15 years should continue. The amount of acreage reclaimed by the mining indus- try should parallel the amount of acreage affected by surface coal mining, which is likely to continue decreas- ing (fig. 26). Noncoal mining operations, which affect significantly smaller amounts of acreage, may increase slightly as demand for raw construction materials increases. The AMLRC will also continue its reclamation efforts for abandoned mine sites as long as coal mining contin- ues in Illinois and a satisfactory level of funding is de- rived from the Abandoned Mined Lands reclamation fee assessment on active mining. Coal operators will no longer be required to pay the reclamation fee after the year 2004, when funding for the AMLRC expires. More than 9,000 acres of abandoned mined lands are still con- sidered to be in need of reclamation (Nutt 1992). BIBLIOGRAPHY BIBLIOGRAPHY Bay, C.A., 1964, Ground Water and Underground Gas Storage: Ground Water, v. 2, no. 4, p. 25-32. Bell, A.H., 1961, Underground Storage of Natural Gas in Illinois: Illinois State Geological Survey, Circular 318, 27 p. Bond, D.C., 1975, Underground Storage of Natural Gas: Illinois State Geological Survey, Illinois Petroleum 104, 12 p. Buschbach, T.C., and D.C. Bond, 1967, Underground Storage of Natural Gas in Illinois: Illinois State Geo- logical Survey, Illinois Petroleum 86, 54 p. Buschbach, T.C., and D.C. Bond, 1974, Underground Storage of Natural Gas in Illinois — 1973: Illinois State Geological Survey, Illinois Petroleum 101, 71 p. Code of Federal Regulations, 1973, Title 18, Conserva- tion of Power and Water Resources: U.S. Govern- ment Printing Office, Washington, DC, p. 288-291. Coleman, D.D., W.F. Meents, C.-L. Liu, R.A. Keogh, 1977, Isotopic Identification of Leakage Gas from Underground Storage Reservoirs — A Progress Re- port: Illinois State Geological Survey, Illinois Petro- leum 111, 10 p. Croke, K.G., A.P. Hurter, Jr., and G. Tolley, 1979, Eco- nomic benefits from abandoned mine reclamation, in H.A. Roberts (editor), Decision Analysis for Aban- doned Mine Reclamation Site Selection and Plan- ning: Illinois Institute of Natural Resources, Document 79/29, p. 134-217. Forbes, S.A., 1925, The Lake as a Microcosm: Illinois Natural History Survey, Bulletin 15, article 9, p. 537— 550. [Reprint of a paper presented in 1887.] Haskin, H.K., and R.B. Alston, 1989, An evaluation of CO? huff ’n puff tests in Texas: Journal of Petroleum Technology, v. 41, no. 2, p. 177-184. Holm, L.W., 1987, Evolution of carbon dioxide flood- ing processes: Journal of Petroleum Technology, v. 39, no. 11, p. 1337-1342. Hughes, R.E., W.A. White, and R.L. Warren, 1989, The history, geology, and future of industrial clays in IIli- nois, in R.E. Hughes and J.C. Bradbury (editors), Proceedings of the 23rd Forum on Geology of Indus- trial Minerals (May 11-15, 1987, Aurora, Illinois): Il- linois State Geological Survey, Illinois Minerals 102, p. 59-70. Illinois Department of Commerce and Community Affairs, 1985-1993, Illinois Economic Summary: bi- monthly reports published by the IDCC Office of Policy Development, Planning, and Research. Illinois Department of Commerce and Community Affairs, 1985-1993, Illinois Gross State Product: quarterly reports published by IDCC. Illinois Department of Energy and Natural Resources, 1990-1992: Illinois Energy Data Review. Illinois Department of Mines and Minerals, 1934-1991, Annual Coal, Oil, and Gas Report. Illinois Department of Mines and Minerals, 1992, An- nual Statistical Report for the years 1990 and 1991, 114 p. Illinois Environmental Protection Agency, 1993, Avail- able Disposal Capacity for Solid Waste in Illinois: Sixth Annual Report, IEPA/LPC/92-219, 111 p. Illinois Environmental Protection Agency, 1991, Avail- able Disposal Capacity for Solid Waste in Illinois: Fifth Annual Report, IEPA/LPC/91-59, 101 p. Illinois Environmental Protection Agency, 1990, Avail- able Disposal Capacity for Solid Waste in Illinois: Fourth Annual Report, IEPA/LPC/90-173, 58 p. Klimstra, W.D., and S.R. Jewell, 1973, Strip mining: re- sources in conflict impacts and reclamation efforts in Illinois: Transactions of the North American Wildlife and Natural Resources Conference, v. 38, p. 121-131. Leighton, M.M., G.E. Ekblaw, and L. Horberg, 1948, Physiographic divisions of Illinois: Journal of Geolo- gy, v. 56, no. 1, p. 16-33. Likens, G.E., and FH. Bormann, 1975, Nutrient-hydro- logic interactions (eastern United States), in A.D. Hasler (editor), Coupling of Land and Water Sys- tems, v. 10: Springer-Verlag, New York, p. 1-5. Miller, B.J., 1990, Design and results of a shallow, light oilfield-wide application of CO2 huff ’n puff process: 27 BIBLIOGRAPHY SPE/DOE Seventh Symposium on Enhanced Oil Re- covery, Society of Petroleum Engineering, Tulsa, Oklahoma, p. 925-932. National Coal Association, 1992, Steam Electric Plant Factors, 186 p. National Research Council, 1993, Solid-Earth Sciences and Society — A Critical Assessment: National Acad- emy Press, Washington, DC, 346 p. Nutt, J. (editor), 1992, 1991-1992 Report of the Illinois Abandoned Mined Lands Reclamation Council: State of Illinois, 13 p. Petzet, G.A., 1983, U.S. industry eyes buildup in oil out- put via CO? floods: Oil and Gas Journal, v. 81, no. 1, p. 39-42. Roberts, H.A., 1979, Introduction and overview, in H.A. Roberts (editor), Decision Analysis for Abandoned Mine Reclamation Site Selection and Planning: IIli- nois Institute of Natural Resources, Document 79/29, p. 1-18. St. Aubin, K., 1990, 1988-1989 Report of the Illinois Abandoned Mined Lands Reclamation Council: State of Illinois, 24 p. Schwegman, J.E., 1973, The natural divisions of IIli- nois: Illinois Department of Conservation, Spring- field, Illinois, map, 1:1,000,000 scale. Stalkup, FI. 1977, An introduction to carbon dioxide flooding, in Proceedings of the Second Tertiary Oil Recovery Conference, Contribution 3, Tertiary Oil Recovery Project: Institute of Mineral Resources Re- search, University of Kansas, Lawrence, p. 108-127. Stewart-Gordon, T., 1990, Huff and puff process offers economic, last ditch try at recovery: The Oil Daily, November 12, p. 9. Surface-Coal Mining Land Conservation and Reclama- tion Act, Ill. Rev. Stat., Ch. 96 1/2, pars. 7091 et seq. Thomas, G.A., and T.G. Monger, The feasibility of cy- clic CO? injection for light-oil recovery: SPE/DOE Seventh Symposium on Enhanced Oil Recovery, So- ciety of Petroleum Engineering, Tulsa, Oklahoma, p. 353-360. 28 U.S. Department of Energy, 1992, State Energy Data Re- port, DOE/EIA-0214(90), 501 p. U.S. Department of Energy, 1976-1992, Coal Produc- tion, DOE/EIA-0118. U.S. Department of Energy, 1976-1992, Coal Distribu- tion, DOE/EIA-0125. U.S. Department of Energy, 1976-1992, Cost and Qual- ity of Fuels for Electric Utility Plants, DOE/EIA- 0191. U.S. Bureau of Mines, 1932-1989, Minerals Year Book, v. 1, 2, and 3. U.S. Department of Energy, 1989, Federal oil research: A strategy for maximizing the producibility of known U.S. oil: Office of Fossil Energy, Oil, Gas, Shale, and Special Technologies, DOE/FE-0139, 27 p. Venuto, P.B. 1989, Tailoring EOR processes to geologic environments: World Oil, v. 209, no. 11, p. 61-68. ee #1. REPORT NO. | 2. 3. Recipient's Accession No. | ILENR/RE-EA-94/05(4) 5. Report Date The Changing Illinois Environment: Critical Trends a Technical Report of the Critical Trends Assessment Project 6 Volume 4: Earth Resources ee fips Subhash B., Leetaru, Hannes E. Sere cen bare MO: D Og 9. Performing Gagnon aa and Aiea 10. Project/Task/Work Unit No. Illinois Department of Energy and Natural Resources St ate Geological Survey Division 11. Contract(C) or Grant(G) No. 615 East Peabody Drive ©) Champaign, IL 61820 ie 12. Sponsoring Organization Name and Address Illinois Department of Energy and Natural Resources 325 West Adans Street Springfield, IL 62704-1892 13. Type of Report & Period Covered 15. Supplementary Notes 16. Abstract (Limit: 200 words) The geologic setting is the foundation of the environment. Ecosystems are influenced by and depend on geologic settings and processes. Geology provides tne unique environmental conditions for the existence of ecosystems. Human activities such as agriculture, forestry, mineral extraction and manufacturing depend on geologic settings. These activities can permanently influence ecosystems. Trends in Illinois in land use, extraction and consumption of fossil fuels and industrial minerals and disposal of wastes have been captured and interpreted in the contexts of geology, the environ- ment and the ever changing regulatory conditions. Land use in Illinois is historically dominated by agriculture. However, the fastest growing land use type is urban expansion. Mineral extraction in Illinois has generally declined. Past impacts of the mineral industries on the environment have moderated as a result of new industrial attitudes. Of growing future concern is not only the availability of fuels and minerals but of clean water. Safe waste disposal must go hand-in-hand with reduction of pollution from industry, agriculture and households. Understanding the geologic context is critical. 17. Document Analysis a. Descriptors Aggregates Minerals Petroleum industry Geology Natural gas Sands Gravel Natural resources Underground storage Land use Oil recovery b. Identifiers/Open-Ended Terms Abandoned mined lands Illinois 0i1 consumption Coal consumption Natural gas consumption 0i1 production Coal production Natural gas production Stone, sand and gravel industry Energy consumption c. COSATI Field/Group ary Set iG restriction on distribution: | 19. Security Class (This Report) {peta Bie: oF eames Available at IL Depository Libraries or from Unclassified 28 National Technical Information Services, [a Secne eon ina Ene) {(peeenerem = ing i Ci} ry) a OPTIONAL FORM 272 (4-77) (Formerly NTIS—35) Department of Commerce See instructions on Reverse rea a San cs ate mre Thanh, 4 te 7. ¢ PE rs won Yee Sipoteey ho bradeb pik Suetaiibbsised stony, Pinte resetureden iter Botvos ete ai efoni i to.agoneni, chad ‘it ATE oratang CTE eID ‘ Rais axe t! 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IL i 7, : t a if \ : i] i ; ' ; Md vr () ‘ : ¢ oa y feel f I hy fi vi a wl ~ " ’ a A fy ve i" “ fi - bi >. ; we ., a ? ‘TA b j ~~ i } 4 ; ‘ I ( ri fi ‘ @ 4 ee mv , v1) cue Lh ity i a Y J ‘ i » 4 ¥ y ' a uh i oe ny j f ; 3) 7 y f Tah , - | i ] ; ” 7 " ey i iti * ~~. | elie a mu / ey a it Hi i ] wl Ait, ae Ye re a st vic > we J ca ij io T D = 1 + I pt an q Ponts “a ure — i ie a We DAP ae i ' es Tr oo | yo : ea \ ies! Ae ae jote® D is ee 1 \ Yr - i ihe a r it i Vy y - mM 7 4X 1 ome UNIVERSITY OF ILLINOIS-URBANA 363.7009773C362 c004 voo4 | THE CHANGING ILLINOIS ENVIRONMENT SPRIN ig. Printed by the authority of the State of Illinois. Printed on recycled and recyclable paper. 3,400/June 1994