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By C Rogers

"The Coal Seam Gas (CSG) industry has seen a rapid increase in activity over a 30-year periodfrom the early 1990s within Australia. Despite public concerns over environmental issues, theCSG industry has increased in Queensland to the point where more than 90 per cent of naturalgas consumed in Queensland is CSG. The New South Wales (NSW) CSG industry has been slowerto respond for many reasons. Ninety-five per cent of natural gas consumed in NSW comes frominterstate. However, CSG activity in New South Wales is increasing notwithstanding publicconcerns. The CSG potential of three Petroleum Exploration Licenses (PELs) are being assessedwithin the Southern Sydney Basin that provides a unique opportunity to develop resourcesstrategically around many abandoned coal mines. The question has been asked - what do theseabandoned coal mines mean to the project? Are they good or bad? Are they friend or foe? Thispaper att empts to answer these questions and in doing so describes the coal mine ventilation andgas management philosophies and practices used to assess gas production potential. The coalmining philosophies not only have the potential to assist in the construction of a highly successfulCSG project, but they also potentially add signifi cant pre production value by re defi ning how theresources and reserves are assessed and therefore valued. The behaviour of abandoned coal minesand the goaves within the PELs are not well understood by the petroleum industry. However, in the Illawarra region there is an abundance of coal mining knowledge and expertise that if properly focused can greatly increase the chances of project success."

Jun 1, 2012

By Wilton Johnson

The development and use of minerals and mineral fuels are essential to national security and to the maintenance of an expanding economy. As a Nation, we often met these needs but failed to recognize and assess the impact that mining and mineral processing activities have on other natural resources. Currently, the growing demand for energy and minerals is accompanied by an increasing awareness that the provision of these resources must not conflict with society's demand for a clean and habit-able environment. Although present mining and mineral processing activities incorporate, or have under development, technology capable of minimizing environ-mental impacts on land, air, and water, many older operations, particularly in the first half of this century, lacked the technological, social, and environmental insights that exist today. Consequently, a substantial backlog of damaging and potentially damaging conditions remains from such problems as mine subsidence, acid water generation, burning and nonburning waste banks, abandoned surface-mined lands, abandoned underground mine fires, and abandoned mine shafts and oil and gas wells.

Jan 1, 1979

Provide a full-scale test facility where the effectiveness of all types of subsidence abatement techniques can be evaluated under controlled conditions. Background Subsidence is ground movement resulting from the collapse of overlying strata into a mine void because of failure of the mine roof, mine floor, or support pillars. The failure may propagate to the surface and be expressed as a depression, cracks, or a sinkhole. The surface expression of such features may be delayed until long after mining has been completed. Subsidence has the potential to affect more land area than any other type of abandoned mine land problem. Subsidence also causes direct damage to real property, with significant financial loss and more importantly, presents a danger to public health, safety, and general welfare. Subsidence-related problems are considered to be one of the most important abandoned mine land issues. Backfilling of mine voids is the most common stabilization method used to abate subsidence and protect surface structures. Backfilling or placement of material is performed by hydraulic flushing or pneumatic stowing, using either in-mine or remote methods. The majority of the past subsidence abatement projects has been performed using remote methods from single or multiple boreholes. Other subsidence abatement techniques arc available. For example, various point support methods are used to protect small areas of the land surface and surface structures, without completely filling the mine void. These may be more appropriate under different conditions. Little documented information is available concerning the capability of the various backfilling methods for completely filling a mine void or providing long-term structural strength. Therefore, the Bureau of Mines developed a laboratory for controlled evaluation of backfilling technologies.

Jan 1, 1991

Assist in controlling or extinguishing fires that occur in abandoned mine lands (AML) by providing a compilation of information on past fire control projects, the estimated extent of the current problem, and factors affecting the occurrence, propagation, and extinguishment of AML tires. Conventional fire control methods and their probable effectiveness are evaluated. Background Fires that occur in abandoned coal mines, waste banks, and coal outcrops constitute a serious health, safety, and environmental hazard from toxic fumes, deterioration of air quality, and subsidence. Although fires on AML occur in every coal-producing State, the severity of the problem varies, with most underground fires occurring in Kentucky, Pennsylvania, and Wyoming. Surface fires are prevalent in Kentucky, Pennsylvania, and West Virginia. Methods to extinguish or control AML fires, including excavation, fire barriers, and scaling, are generally expensive and have a relatively low probability of success (see figures 1 and 2). Bureau of Mines Study The Bureau compiled information from a variety of sources and found that the problem of AML fires is a serious one. Such fires can involve a high degree of hazard and can be difficult and costly to control. AML fires usually involve smoldering combustion in outcrops, waste banks, or abandoned mines. Given the nature of these fires, it is unlikely that the extent of the problem or the cost of solutions will decrease in the near future.

Jan 1, 1992

Develop a safer, more effective, and more efficient method to control fires in abandoned coal mines and waste banks. Maintain the costs of this new method at less than or comparable to conventional AMI fire control methods. How It Works Cryogenic extinguishment of subsurface fires is a method of heat transfer. Bureau-designed injection equipment produces a pumpable slurry of liquid nitrogen and solid particles of carbon dioxide. Liquid or gaseous carbon dioxide from a pressurized tank flows to a bell-shaped nozzle where the change in pressure causes the carbon dioxide to form a granular snow. The solid carbon dioxide is mixed with liquid nitrogen. A jet pump is used to move the slurry through the delivery lines and into a simple injection probe. At injection, the nitrogen vaporizes and the carbon dioxide sublimes. This phase change produces a cold gas (-180° C) that, as it expands and moves in all directions, removes heat and also displaces oxygen. This combined process inhibits the combustion process and lowers the temperature below the reignition point. When the liquid nitrogen and solid carbon dioxide are converted to gases, the expanding gas acts like a piston, forcing warm air out of the porous bed, Although smoke and hot gases arc forced from the burning coal, generally there is no significant increase in the odor associated with burning coal.

Jan 1, 1992

Treat contaminated coal mine drainage to meet EPA and State water quality requirements. Approach A model (fig. 1) is presented for selecting, designing, and sizing one or several passive mine drainage treatment systems that can be used in remediation of abandoned mine lands (AML). The three principal types of passive mine drainage technologies for the treatment of coal mine drainage are an aerobic system, a compost wetland, and an anoxic limestone drain. The multistep approach presented here provides a simplified method to characterize the type and magnitude of the water quality problem and then to select either a single treatment system or a combination of treatment systems to address the specific site situation. How It Works Step 1. Discharge Characterization. Characterization of the discharge consists of measuring the discharge flow rate and collecting water samples at the point of discharge for chemical analysis. Both the flow rate and chemistry of a discharge can vary seasonally and in response to storm events. It is important to account for this variability by determining flow rates and water chemistry under various conditions.

Jan 1, 1992

Determine the extent to which remote-sensing techniques, primarily lineament analysis, can be used to identify geologic structures that may affect the location and migration of subsidence over abandoned underground coal mines in the Colorado Springs, CO, area. Compile data using a geographic information system (GIS) to allow efficient and reproducible comparisons and analyses. Background The basis for evaluating abandoned mine land (AML) sites with remote-sensing techniques comes from past and ongoing Bureau ground control research using remote-sensing data to identify potential hazards caused by geologic structures (faults, joints, etc.) above active underground coal mines. Research showed that lineament (linear feature) analysis of Landsat Multispectral Scanner (MSS) images could indicate locations of fractures and fracture trends that had varying, but significant, impacts on the stability of mine openings. Such geologic structures should be identifiable over abandoned mines as well. If fractures are present, even if they arc not faults, they should represent areas of potential instability over these mines and, therefore, should tend to localize subsidence when it occurs, particularly for deep and moderately deep portions of mines.

Jan 1, 1992

Identity the difficulties of establishing vegetation on mining-related wastes resulting from adverse chemical, physical, and biological properties; describe the ecological and soil factors affecting the relationship between mycorrhizal fungi (soil microorganisms) and plants; and evaluate the feasibility of establishing vegetation on mine waste by introducing mycorrhizae. Problems in Revegetation Successfully using vegetation to stabilize a situ disturbed by mining-related activities depends on knowing the chemical, physical, and biological characteristics of the site prior to, or at the time of, stabilization. The primary objectives of mine land reclamation are to minimize environmental degradation and to facilitate the re-establishment of a functional plant-soil system. Mining disturbances can significantly alter the physical, chem¬ical, and biological characteristic of a site, thus affecting plant establishment, survival, and growth. The physical disturbance caused by the removal and replacement of soil and overburden, together with the waste material from ore processing, affect the chemical, physical, and biological process within the disturbed soil or waste. Additionally, variability in soil properties results from differences in climate, topography, vegetation, and parent material of the site.

Jan 1, 1993

Determine the effectiveness of remining operations in reducing contaminant load (acidity, iron, and sulfate) of discharges emanating from abandoned surface and underground coal mines. Background Until the implementation of remining initiatives, most States had regulations that held the operator remining an abandoned site responsible for preexisting acid mine drainage (AMD) discharges. For example, if a mining. company wanted to remine an area hydrologically connected to an existing AMD discharge, the company became responsible, as soon as the site was activated, for treating that discharge to meet effluent standards. If the mining operation improved the quality of the discharge, but the discharge failed to meet effluent standards, the company was held accountable for perpetual treatment. Because of this regulation, most mine operators avoided abandoned sites with minable coal reserves and AMD discharges. However, changes in remining legislation allow coal companies to be released from treatment liability as long as the post-remining pollution load does not exceed the pre-remining level. If remining can improve water quality through improved mining and abatement techniques, abandoned mine land (AML) areas that previously were liabilities could become

Jan 1, 1994

Develop a method to evaluate the effectiveness of coal scam fire surface seals so that potential problems may be corrected at an early stage, before the integrity of the surface seal is lost. Background Surface seals are the primary coal seam fire abatement method being used in the western United States. Surface seals smother a fire by denying it oxygen. The seal is usually constructed by placing a mantle of soil, four to ton feet thick, over a coal scam fire area to exclude air from the fire. The soil is compacted to increase effectiveness, and a soil cement may be used to augment the soil. In some cases, burning coal may be excavated and separately smothered or otherwise extinguished in another area; in other cases, a trench maybe excavated and backfilled with incombustible material to isolate a fire. More often, a surface seal is simply applied over and around the entire known burning area. In the 1950's, the Bureau of Mines administered a large program to treat numerous coal seam Fires across the western United States. Methods used in this program were described in Bureau of Mines Information Circular (IC) 7932, dated 1959. More recently however, various coal seam fires have been treated with surface seals under the direction of state Abandoned Mine Land Reclamation authorities. It has frequently taken years to evaluate the effectiveness of surface seals. By the time problems become evident, it has often been too late to take corrective action within the scope of the original abatement project. For this reason, the Bureau of Mines developed a means for tracking temperature trends at coal seam fire projects to obtain a better and earlier handle on the effectiveness of surface seals.

Jan 1, 1991

Control surface stream loss by identifying and selectively sealing water loss zones in stream channels overlying underground mines. Approach Electromagnetic terrain conductivity surveys, coupled with stream gaging, are performed within a stream channel to identify saturated fracture zones associated with loss of stream water. This information is used to target locations for the injection of expandable polyurethane grout. The grout is injected two to three feet beneath the surface of the strcambed, across each loss zone, to seal the fractured strcambed and restore stream flow across the damaged area. How It Works Multiple zones of infiltration (natural and induced) normally exist in stream channels overlying mined areas, causing water handling and/or acid drainage problems in the mines as well as loss of stream flow. It is typically difficult to accurately locate these loss points. Therefore, Conventional methods of stream repair, such as using plastic membranes or clay and rock rip-rapping, are applied to long lengths of a stream channel. The two step approach developed by the Bureau of Mines First quickly and accurately locates loss zones using electromagnetic ground conductivity survey and gaging instruments. Conductivity is measured at fixed spacings (typically 25-50 ft depending on the instrument and desired observation depth), Ground conductivity increases when saturated conditions exist at depth. These apparent flow loss zones are confirmed by gaping, to eliminate possible effects due to unobservable metal debris adjacent to or buried in the stream sediment.

Jan 1, 1991

Investigate and demonstrate the possible use of low-density (45-lb/ft3) foam concrete for sealing abandoned mine openings. Although foam concrete has been used in the construction and geotechnical industries for some decades, it has not previously been used in abandoned mint shaft reclamation. Approach A structurally engineered permanent mine seal for an abandoned coal mine shaft, using low-density foam concrete and other appropriate structural materials, was designed by the Bureau and installed at a field site, the No. 22 Shall in Logan County, West Virginia. The field work was conducted by a private contractor under the supervision of the West Virginia AML Section (WV AML). The No. 22 Shaft is situated immediately adjacent to a frequently traveled county road. A few feet away from the shaft is a branch of Pine Creek. On the other side of the road is a railroad line that serves an active mining operation located several miles away. The shaft measures 9.5 by 9 feet in cross section and is about 300 feet deep. It was used at one time as a dewatering shaft and still contains two large-diameter dewatering pipes with steel drive shafts inside them. Before the beginning of the reclamation, the shaft included a concrete cap a few inches thick, with a 4 - by 5-foot access opening covered by a steel grate. The interior of the shaft was quite humid, and considerable flow of water at the bottom of the shaft could clearly be heard from the surface. Methane tests were conducted that showed the shaft to be clear of this gas.

Jan 1, 1992

Validate the premise that there is measurable seismic activity associated with abandoned mint lands and that this activity can be used to determine stability of the abandoned mine openings, failure cycle of these openings, and susceptibility of the area to surface subsidence. Approach The U.S. Bureau of Mines conducted field investigations at two geologically contrasting sites, Colorado Springs, CO, and the Allegheny Portage Railroad Historical Site near Cresson, PA, to demonstrate that developing monitoring technology can be applied to any site. An array of seven geophones (velocity-measuring sensors) were strategically located to encompass an area at each site where failure in the underground mine openings could be expected, based on historical, geological, and engineering information. How It Works Bureau research has effectively demonstrated that stress changes within a rock mass can stimulate the development of cracks and fractures, resulting in the release of strain energy that generates seismic waves. These seismic waves, traveling outward from their source, can be detected, and the point of origin can be located in three-dimensional space. Furthermore, these seismic signals contain information that defines the source mechanism and the conditions between the source and the receiving sensor.

Jan 1, 1992

To develop a cost-effective tool for improving the performance of rock drilling systems used in detecting and delineating underground mine voids and for coal exploration. Approach To investigate admixtures of polyethylene oxide (PEO) at zero surface charge concentrations as drilling fluid additives to enhance penetration rates and extend bit life in rock drilling systems. Background Bureau researchers have investigated the use of chemical additives to enhance drilling performance and found that the most efficient drilling occurred when the drilling fluid was able to maintain a zero surface charge (ZSC) on the surface of the rock being drilled. Laboratory drilling studies have been performed on rock types such as quart¬zite, granite, taconite, and marble. The lab tests were conducted using 5/8-inch diameter diamond-impregnated coring bits with cationic compounds as the surface charge neutralizing additives. These studies demonstrated enhanced drilling performance, however, only at the singular additive concentration that produced the ZSC condition.

Jan 1, 1991

Produce an annotated bibliography to serve as a comprehensive source of published information available on the use of soil amendments in coal mine reclamation and the characterization of coal mine soils. The Problem There is a substantial amount of information available tin coal mine reclamation and revegetation, particularly on the use of soil amendments to ameliorate site conditions and aid vegetation establishment, growth development, and productivity. Additionally, site characterizations based on chemical, physical, and mineralogical properties have been thoroughly researched. This information, however, is widely disseminated throughout various professional and scientific journals, State and Federal documents, proceedings of conferences, theses, and other technical writings. A critical need exists for a comprehensive and up-to-date summary of published information concerning the uses, methodologies, and types of soil amendments that arc necessary for reclamation success.

Jan 1, 1991

Develop a cost-effective, flexible method for extinguishing underground coal mine Fires that can be readily used in fire conditions encountered in both abandoned mines and coal outcrops. In addition to the abatement of an underground coal fire, a secondary objective was to prevent subsidence by filling the voids with a material having sufficient compressive strength to minimize subsidence. Approach The Colorado School of Mines Research Institute was awarded a research contract to determine the viability of using Foaming Mud Cement for abating underground coal mine fires and preventing subsidence. The program consisted of a laboratory and pilot scale investigation and process development. An extensive, controlled test program was conducted simulating floor, rib, roof and rubble fire conditions. Field demonstrations were conducted after the pilot scale research was completed. How It Works Traditional techniques have targeted the control of burning by eliminating the air, fuel source or heat. This has been accomplished by trenching, quenching, mothering or combinations of these three methods. These techniques were not always successful, particularly in the case of fires in abandoned mines.

Jan 1, 1991

Detect hazards associated with abandoned mine openings through the use of integrated geophysical technology. Background Many abandoned mines in the U.S. present hazards to the public. The first step in abatement of these hazards usually requires locating the abandoned workings. Recent Colorado legislation resulted in a concerted effort aimed at mitigating the hazards associated with abandoned mine workings. The Colorado Department of Natural Resources-Mine Land Reclamation Division (CDNRMLRD) is responsible for locating and backfilling abandoned mine openings such as shafts, adits and collapsed features. Many shafts and adits can be located by inspection, other openings give little or no surface expression and must be located by drilling, or through the use of geophysical methods. A common method used for locating underground mine workings is to drill throughout the suspected area. However, it is prohibitively expensive to drill holes at the spacing needed to detect backlilled shafts and small voids associated with caving and/or chimneying. It may also be dangerous to move heavy equipment over shallow mined-out workings. Geophysical investigations that employ only a single method have had mixed success in detecting hazardous abandoned mine land cavities.

Jan 1, 1991

By J. J. Gusek

The Riley Pass strip mine is an abandoned uranium-bearing lignite deposit in Harding County, South Dakota, covering about 150 acres of highwalls, pit floor and mine spoils exhibiting elevated levels of radioactivity. Six reclamation design alternatives were developed, ranging from doing nothing to reclaiming to approximate original con-tour. The alternatives were evaluated for expense, site stabilization, and mitigation of public safety hazards. A comparative economic evaluation on three of the alternatives was completed for the Forest Service in selecting an alternative and substantiating federal funding requests. This evaluation included economic impacts associated with physical and radiologic health hazards, affects on recreational users, socioeconomic impacts and environmental improvement.

Jan 1, 1995

By Daryl L. Gusey, John T. Neubert, Matthew A. Sares

The Colorado Geological Survey completed an inventory of environmental degradation associated with abandoned and inactive mines on National Forest System lands in Colorado. In the course of the inventory, areas with naturally occurring acid rock drainage were also noted. Approximately 18,000 abandoned mine- related features were inventoried, including about 900 features that are considered significant enough environmental problems to warrant further investigation. Water quality data, such as pH and conductivity were gathered at all features where water was present, such as draining adits, seepage at the toe of dumps and tailings, and standing water in shafts. Samples were taken where field tests indicated low pH andlor high conductivity, including several areas with naturally occurring acid rock drainage. Samples were analyzed for dissolved and total metals, and for selected anions. All mine locations and data collected by the field geologists were entered on field forms and, subsequently, into a computer database and GIS format. With the information provided by the inventory, the Forest Service, in cooperation with other agencies, has been able to prioritize abandoned mines for reclamation. In most cases, cleanup is approached on a watershed basis. Mines in priority watersheds have been selected for reclamation first. Watersheds where studies prerequisite to cleanup are occurring include the upper Anirnas River, Willow Creek (tributary to the upper Rio Grande), Chalk Creek (tributary to the upper Arkansas River), the Uncompahgre River, and the Alamosa River. During the inventory, evidence of naturally occurring water quality degradation was found in areas where little or no evidence of mining activity exists. These areas include the upper Alamosa River, the Middle Fork of Mineral Creek, Peekaboo Gulch, and Handcart Gulch. Water from these natural sources has been found to significantly exceed Colorado water quality standards for several metals.

Jan 1, 2000

By Cathleen J. Webb, Arden D. Davis

Begun in 1992, an abandoned and inactive mine inventory in the Black Hills National Forest has resulted in a hazard ranking of the most severely affected sites. For purposes of the inventory, the Black Hills were divided into three main regions: the northern Black Hills, with primarily gold mines; the central Black Hills, with pegmatite mines and some gold mines; and the southern Black Hills, with primarily uranium mines. A computerized data base has been developed along with standard forms for field crews. The forms were designed to provide maximum compatibility with other abandoned mine inventories on various federal and state lands. Measures recommended for the most hazardous and heavily affected sites include regrading of unstable slopes, fencing of open shafts, and remediation of the most severe acidic mine drainage problems. Specific examples are illustrated where remediation and safety measures were recommended or have been implemented. The vast majority of the sites, however, needed little or no remedial action.

Jan 1, 1995