ABSTRACTS

Multiple-Seam Mining Interactions in Underground Coal Mines: Regulations and Technical Studies

Yi Luo and Gary L. Winn, West Virginia University

 

Multiple-seam mining (MSM) operations refer to the mining operations conducted by one or more mine operators in closely-spaced multiple coal seams.  Unlike more conventional mining operations conducted in single-seam situation, these MSM operations and their interactions could bring some unique technical, safety and regulatory issues to the attention of mine regulators, operators and engineers.  This report primarily addresses the technical issues and mining best-practice surrounding MSM, but also discusses the safety and regulatory concerns associated with MSM.

 

Technical Difficulties with MSM Operations:

 

If not well coordinated, MSM operations can cause many unexpected consequences to active and inactive mines in the influence ranges – MSM interactions.  Among the various MSM interactions, the interactions caused by the large strata movements and deformations in the ground subsidence process in the overburden strata, and especially the interburden (in-between) strata, must be critically examined.  When large deformations are concentrated in neighboring areas, they can form leakage paths for water, gas and air to flow between the coal seams in addition to disturbances to mine structures in the mines.  The flow of these liquid and gases from previous mines to active mine can cause significant ventilation and safety problems such as inundation (e.g., the accident at Quecreek), or gas explosions as may have happened at Upper Big Branch.

 

Using Computer Models to Accurately Predict Subsidence:

 

Numerical modeling techniques have been developed and applied to study the MSM interactions.  However, most of the modeling methods assume continuity in media that deviated from the coal measure rock strata that contains various preexisting and mining induced horizontal bedding planes, vertical or sub-vertical fractures.  Because of this, these methods have difficulty in accurately assessing the MSM interactions associated with large-movements and large deformations strata subsidence process.  On the other hand, subsidence theories, well suited for dealing with large strata movements deformations caused by mining operations, can be applied to study the MSM interactions.  Recommendation: Future research should concentrate on improved computer models, which consider issues involved in MSM operations including large seam displacements, jointed and refractive strata and software developed for use in known MSM operations.

 

Coordinating the Legal Rights to Multi-Seam Operations:

 

In countries outside the U.S., the mine owner typically owns the rights to all of the coal reserves which may be located in a single seam, or in overlying seams.  Because there is no is-sue of “who owns what”, coordination operations is an important matter.  But in the U.S., however, one owner often owns rights to a particular seam, but not the rights to an overlying or underlying seam.  Coordinating mining operations becomes a central issue, and this is even more important when old mine workings are found in a different seam or the old workings have poor maps.  Even though as early as 1883, mine maps were required to be provided to the state of West Virginia, many mines were abandoned without proper historical maps. Since the pas-sage of mine map legislation on both state and federal levels, the agencies involved including U.S. Department of Interior, Office of Surface Mining and the West Virginia Office of Miners' Health, Safety and Training and the WV Geological and Economic Survey, plus West Virginia University have worked in cooperation to acquire maps and to index and digitize them. Currently, over 60,000 images have been digitized and indexed for West Virginia mines (WV Office of MHST, 2013).  Recommendation: For future research, a coordination and archiving project ought to be undertaken to voluntarily share or even force sharing information about owner-ship rights but also scheduling, design, and planning of MSM mines.

 

Updating Permitting Procedures:

 

Federal and State regulatory agencies require a complete set of engineering, safety and environmental designs to be approved prior to undertaking mining activity. Unfortunately, multi-seam mining and the possible seam or ownership interactions are not considered or not sufficiently considered in the permitting process.  While future research could easily pinpoint situations when failure to consider MSM interactions have had harmful consequences, this recommendation must be properly aimed at the regulatory agencies and perhaps legislative bodies in order to make it a priority to consider MSM variables in the permitting process.  Recommendation: state and federal regulatory agencies should follow the lead of Congress and/or the State legislature in causing the promulgating of rules to require the consideration of MSM operations early in the mine permitting process.

 

Summary:

 

While technical understanding of the MSM process has improved significantly in recent years, and while a good amount of research has been performed and some numerical-modeling based design tools have been developed for dealing with the load transfer MSM interactions, problems persist.  In particular, problems with MSM operations need to update computer subsidence models they currently use to include large displacement algorithms, for example.  Second, MSM operators and state and federal regulatory agencies need to coordinate the use of maps especially, but also and general information about scheduling and methods in order to coordinate activities and not act in secret as is done now. Finally, acting on the lead by Congress and/or state regulatory agencies, the permitting process must have rules promulgated to include the consideration of MSM operations.   All of these would work to improve MSF safety.

 

 

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Identifying Improved Control Practices and Regulations to Prevent Methane and Coal Dust Explosions in the United States.

Benjamin Goertz and Jürgen F. Brune, Colorado School of Mines

 

This research study investigates and analyzes methods for the prevention of coal mine explosions in the United States and compares them to those used in other leading coal mining countries. Primary purpose of this research is to identify the best practices for the prevention of methane and coal dust explosions in underground coal mines.

 

The report is focused on rock dusting, mine dust sampling and analysis, methane and mine ventilation monitoring, rock dust inspection procedures and various types of explosion barriers.  It will compare the regulatory standards and industry practices in the United States with those in other leading countries, including Australia, Germany, Great Britain and South Africa.

 

The report examines the following:

 

a. Key technical and engineering factors for methane and coal dust explosion prevention

 

Researchers have investigated and analyzed which explosion prevention strategies are being employed by mine operators in the U.S. and other leading mining countries.  Prevention of methane explosions relies fundamentally on eliminating ignition sources and diluting accumulations of explosive methane with adequate ventilation.  Proper ventilation, ventilation engineering and ventilation system monitoring are key components for the prevention of methane accumulations. Prevention of coal dust explosions is done by using sprays to reduce the formation of coal dust, rock dust inertization, trapping of coal dust with hygroscopic salts and explosion barriers.

 

b. Mine safety regulations pertinent to methane and coal dust explosion prevention

 

Researchers have examined the regulatory standards for preventing mine explosions, including equipment standards and general ventilation principles, in the United States and compared them to standards in other countries.  In particular, researchers have investigated:

 

i. Inspection and monitoring procedures with regard to ventilation systems, the presence of gases and the application of rock dust.

ii. Regulatory structures and requirements pertaining to ventilation procedures for the prevention of methane and coal dust explosions.

 

c. Methane and coal dust explosion prevention practices deployed around the world

 

Researchers have investigated rock dusting and mine dust sampling procedures, analysis protocols for atmospheric systems and methane controls.  Researchers have characterized the current state of the art internationally and to compared it to practices in the USA.

 

In U.S. mines, methane is primarily controlled through dilution and methane drainage, while coal dust explosions are controlled by inertizing coal dust with (limestone) rock dust.  In addition to these methods, other countries use both passive and active methane and coal dust explosion barriers, hygroscopic pastes to bind coal dust, and mine-wide atmospheric monitoring to control both face ignitions, explosions and fires in sealed areas. European technology on active, triggered explosion barriers is mature and may be applicable, either directly or with adaptations, to US mines.

 

Researchers also found that, compared to the U.S., the ventilation and atmospheric monitoring practices are more elaborate and monitor ventilation air quantities as well as critical gas concentrations.  Also, open-flame and spark generating work such as flame cutting and welding is handled much more restrictive than in the U.S.

 

Key research work that has been analyzed and documented includes

i. Coal dust inertization with rock dust or hygroscopic pastes (Work by the US Bureau of Mines / NIOSH, German, Polish, British and Australian

research institutes etc.);

ii. Passive explosion barriers and their application; arriers and their application;

iii. Active explosion barriers and their application;

iv. Rock dust sampling and sample analysis procedures;

v. Methane drainage;

vi. Mine-wide atmospheric monitoring, including in gobs and sealed areas.

 

d. Suggestions for regulatory improvements and new research

 

This research study identifies suggestions for improvement of explosion control practices and new research on current rock dusting and rock dust sampling methods that would be applicable to all US coal mines and that would significantly improve coal dust explosion safety.  Major improvements can be made through comprehensive air quantity and quality monitoring throughout the mines.  Gases monitored should include, at minimum, methane and carbon monoxide.  Along with monitoring the ventilation air quantities at all critical points in the mine, malfunctions and inadequacies of the ventilation system can be easily detected and appropriate steps taken to mitigate the explosion hazard.  Likewise, rock dust inertization must be monitored more carefully to ensure that coal dust is properly mixed with adequate amounts of inert dust.

 

Both passive and active explosion barriers are widely used in Europe and South Africa and may also offer opportunities for substantial improvements in explosion prevention in the U.S. mining industry.  Research is required to adapt these barrier technologies to U.S. mine geometries and mining equipment used in the U.S.

 

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Lessons Learned from Mine Disasters: New Technologies and Guidelines to Prevent Mine Disasters and Improve Safety

Jürgen F. Brune and Benjamin Goertz, Colorado School of Mines

 

This research report examines 25 recent mine explosion disasters in the United States and in foreign countries.  The official investigation reports of these disasters were consulted to understand and identify the main factors causing the explosions and steps that could have been taken to prevent them.  Specifically, researchers focused on:

 

• the circumstances that led to each explosion

• what monitoring systems had been in place to warn of the explosion hazards

• what additional safeguards had been in place

• where safeguards had failed

• what best practices could be offered to mine management to prevent such explosions.

 

Common themes to these mine explosions are:

• Inadequate ventilation that leads to the accumulation of methane gas

• Failure to monitor mine ventilation and to notice the methane accumulations

• Inadequate inertization of explosive coal dust

• Carelessness in the control of ignition sources, including explosives used for blasting, smoking materials and sparks from mechanical cutting.

 

Mine explosion hazards have been aggravated by the increasing amount of fine coal dust produced by highly mechanized mining equipment.  Also, greater production rates tend to produce more methane that must be diluted by the ventilation system.

 

To illustrate the potential problems created by an inadequately designed and operated mine ventilation system, in the second part of the report, researchers have focused in greater detail on the Upper Big Branch Mine Disaster.  The explosion at the UBB mine killed 29 miners in Montcoal, WV on April 5th, 2010 and was initially triggered by an ignition of a relatively small amount of methane-air mixture.  This ignition was a common face ignition that might have injured a few miners in the immediate vicinity yet would not typically have led to a mine-wide disaster.  However, when the methane explosion stirred up coal dust that had not been sufficiently inertized by adding rock dust, the explosion propagated through nearly 50 miles of mine entries1, killing 29 miners by causing CO poisoning, traumatic and burn injuries.  This analysis will be based on official investigation reports published by MSHA, the WV Office of Miner’s Health, Safety and Training, the WV Governor’s Independent Investigation Panel and additional, detailed information about the UBB explosion including witness testimony available on MSHA’s website.

 

Researchers have developed a complete mine ventilation numerical model of the UBB mine that identifies deficiencies in the mine ventilation system that could have led to the initial methane gas diffusion flame and explosion.  This analysis constitutes an innovative approach as, to the knowledge of CSM researchers, a complete pre-explosion mine ventilation network analysis has not been completed for the UBB mine.  The ventilation numerical model has revealed how the mine ventilation at UBB may have been flawed and how the ventilation system would have responded to the blockages in the headgate and tailgate bleeder entries from roof falls and water accumulations that had been identified in the official investigation reports.  Understanding the UBB mine ventilation system is important to analyze what led to the accumulation of methane gas that initiated the explosion, and it can serve as an example to illustrate the explosion hazards that result from inadequate mine airflow monitoring in all mines.

 

In the third part of the report, researchers have conducted a computational fluid dynamics (CFD) air flow analysis for the longwall tailgate area at the Upper Big Branch mine.  This analysis helps understand how explosive methane could have reached the longwall shearer cutting drum and ignite without triggering an alarm from the various, available and likely, working methane sensors on the tailgate drive and on the shearer itself.  It should be noted that such face ignitions are quite common in the U.S. mining industry, with MSHA statistics showing 33 face ignition and explosion events in 2010 (including the UBB disaster) and 34 face ignitions in 2011.  This analysis also constitutes an innovative approach:  CSM researchers have used CFD analysis for a similar study that can be directly applied to the UBB explosion and other, similar scenarios.

 

1 Based on calculations from data provided by Page NG et al., 2011:  Report of Investigation, Fatal Underground Mine Explosion, April 5, 2010, Upper Big Branch Mine-South, Performance Coal Company, Montcoal, Raleigh County, West Virginia, ID No. 46-08436, Mine Safety and Health Administration, Arlington, Virginia, 2011, 965p., p. 68

 

 

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The interview process related to an evaluation of a mining, safety, and health project: challenging contexts and conversations.

Roundtable Presentation 843 at the American Evaluation Association annual conference, Minneapolis, MN.

Debbie Piecka, Laurie Ruberg, Catherine A. Platt, & Dr. Rodney Hopson

 

This presentation highlights the interview process related to evaluation of the Mining and Industrial Safety, Technology, and Training Innovation (MISTTI) project. MISTTI seeks to improve worker health and safety by facilitating the introduction of new and existing technologies, training, and technology transfer approaches from government and private research facilities into the mining industry. The project includes five tasks: management (including evaluation), worker safety training, mine of the future, International Mining Health and Safety Symposium, and mine and safety rescue technologies. The interview team includes two project evaluators, a project associate, two external evaluators, a doctoral student, and her faculty advisor. Interviews with key stakeholders assist the evaluation team in analyzing project activities, outputs, and outcomes. Discussion will cover the collaborative interview process, challenges with the process, stakeholder group categorization, interviewee nomination, task-related question identification, analytical tool development, theme coding and identification, and application of concepts to the project’s logic model.

 

 

​AEA Handout (PDF)

 

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Evaluating Mining Safety and Health Training, Technology Transfer, and Communications.

American Evaluation Association annual meeting, November 2-5, Anaheim, CA.

Laurie Ruberg & Debbie Piecka

 

​AEA Handout (PDF)MISTTI Poster (PDF)

 

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Health, Safety, and Coal Mining Jobs.

Student Research and Scholarship Symposium, Wheeling Jesuit University, Wheeling, WV.

Kibonge, L. B., Laurie Ruberg, & Charles A. Wood

 

This research investigates the health and safety of a career as a coal miner compared to other occupations. Are coal miners more likely to suffer greater health consequences as a result of their occupational exposures than other similar occupations? How do the statistics for U.S. coal miners compare to those of other countries? Are coal mining labor positions today safer than they were 20, 40, 60, 80, and 100 years ago? The Mining and Industrial Safety Technology and Training Innovation (MISTTI) project provides the context for this research. This project analyzes how other jobs such as farming, transportation industry (trucking, shipping, and trains), gas production, off shore drilling can be dangerous and how they differ from coal miners jobs. This analysis compares the fatality rates of U.S. miners to rates in other countries such as Australia, South Africa, China, and South Korea. This study also includes a summary of information on safety and mining published by newspapers and websites that provide information about changes in mine safety regulations and technology improvements. Based on all the news and information gathered, the researchers present a summary of relative risk  for the coal miner by country. We provide a comparison of government regulation, data management, and protection of worker safety country. This research concludes with a summary of health and safety risk, compared with the variety of benefits of coal mining jobs such as salary, job security, and opportunity for advancement.

 

​Research Poster (PDF)

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Task 3-3 Final Report, MISTTI GEO-27

Joe Donovan, WVU

 

The intersection of underground coal mines by natural gas wells creates the potential for a variety of safety, environmental, and economic concerns. Gas wells can intersect either closed or active underground mines, or alternately become mined around in future coal operations. In this task, we will be concerned primarily with closed mines, as mine-safety related to gas wells in active operations is well codified in federal and state mine-safety regulations (e.g., MSHA regulations in 30 CFR § 75.1700 for oil and gas wells). The recent boom in drilling of Devonian shale-gas wells has accentuated both safety- and environmentally-related risks associated with intersecting old mines. The purpose of this task is to gain an understanding of how and where shale-gas operations may influence or interact with local underground mine-water resources of the Appalachian region.

 

​Task 3-3 Final Report

 

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Task 3-4 Mobile Robot Scout: Mapping and Navigation Sensors for the Mine of the Future

Uland Wong, Aaron Morris, Warren Whittaker, James Lee & Red Whittaker, CMU

 

Carnegie Mellon University in association with AM Holdings undertook one year of research in support of the MISTTI project for Wheeling Jesuit

University. The research focus was on Task 3 Mine of the Future, subtask 3.4 Mobile Robot Scout. The work established tasks for a Mobile Robot

Scout; developed, refined, and operationally tested a mobile robot scout user interface; conducted analysis of sensors for use in underground mapping

and navigation; and produced a culminating demonstration showing the following:

 

•       Robot-assisted mine rescue where a mobile robot forged ahead of a mine rescue team to relay mine conditions.

•       Robotic inspection where a mobile robot monitored a specific section of mine for abnormal conditions.

•       Robotic modeling where a mobile robot surveyed and documented an “accident scene” and built a mine model for training and virtual reality.

 

Mobile Robot Scout represents a technology where a robot is equipped to serve as a component for mine accident response and daily monitoring of a working mine. Outfitted with sensing, computing, and communications the Robot Scout is enabled to model and map, sense the environment, locate itself within the mine, navigate the mine, and operate autonomously. The quality of data that is collected results in models that are geometrically accurate, images that are of high resolution, coverage that is complete, and overlays other sensor data such as gas levels and air flow. Processing of the data provides display of the results from simple maps to virtual reality models. A user interface allows a responding rescue team to directly interact to gather information from the Robot Scout and to direct the scout’s mission. The robot can be locally operated by joystick however autonomy allows the operator to command the robot to move forward reverse or to make a turn with a single command and the robot navigates locally around obstacles until the next command. When given a simple plan or previous map the robot can carry out a mission with no human interaction. Integrated into a working mine, the scout will continuously carry out missions to systematically gather information tied with location and time generating data for analysis and identification of changing conditions. This report is comprised of five main sections covering the work from the project.

 

Publication:

Wong, Uland; Morris, Aaron; Lea, Colin; Lee, James; Whittaker, Chuck; Garney, Ben; Whittaker, Red, "Comparative evaluation of range sensing technologies for underground void modeling," Intelligent Robots and Systems (IROS), 2011 IEEE/RSJ International Conference on , vol., no., pp.3816,3823, 25-30 Sept. 2011

doi: 10.1109/IROS.2011.6094938

 

Abstract: This paper compares a broad cross-section of range sensing technologies for underground void modeling. In this family of applications, a tunnel environment is incrementally mapped with range sensors from a mobile robot to recover scene geometry. Distinguishing contributions of this work include an unprecedented number of configurations evaluated utilizing common methodology and metrics as well as a significant in situ environmental component lacking in prior characterization work. Sensors are experimentally compared against both an ideal geometric target and in example void environments such as a mine and underground tunnel. Three natural groupings of sensors were identified from these results and performances were found to be strongly cost-correlated. While the results presented are specific to the experimental configurations tested, the generality of tunnel environments and the metrics of reconstruction are extensible to a spectrum of outdoor and surface applications.

keywords: {Accuracy;Cameras;Laser radar;Measurement;Robot sensing systems;Sensor phenomena and characterization},

URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6094938&isnumber=6094399

 

​Task 3-4 Mobile Robot Scout

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Mine Safety Impoundment Inspection and Verification Tool: Phase 1 Final Report

John Quaranta, Eric W. Baker, Paul Ziemkiewicz, & Melissa O’Neal, WVU

 

The purpose of this investigation primarily focuses on coal impoundment safety and early hazard potential awareness as well as addressing the need for adapting a field hardened computer so that its more advanced technology may be applied to the mining industry. The purpose was to develop a protocol based on West Virginia State and federal laws and regulations and use a mobile field computer into the inspection system for coal waste impoundments. The inspection template was constructed using paper forms presently used by MSHA and the West Virginia Water Research Institute and iterated after conducting a number of field trials. Throughout the duration of conducting field trials, many new features were created such as the inclusion photos with corresponding GPS coordinates as well as a means of recording the entire path the inspector travels while inspecting. Some features were also amended to include more text fields which will allow the inspector to comment on problems as they arise in the field instead of commenting on all problems on one part of the inspection form. A method was developed for saving the inspection file and exporting it to supplementary software for obtaining a finalized output report, which automatically populates based on the inspection information available in the file.

 

Overall, the procedure developed with the technology and software met the tasks within the scope of the investigation. The benefits of this mobile field computer include the ability to store more information for a field inspection including geotagged photos and expedite the inspection process by providing a resource for email and automated data storage. Utilizing the mobile field computer for impoundment inspection will improve the quality of the inspection practice as well because the information can be time stamped, which will show the time duration spent on each portion of the dam. Time stamping can be employed as a method of guaranteeing that the inspection is performed correctly and more importantly, may persuade inspectors to be more thorough in their practice. The automated inspection form will improve the coal impoundment inspection practice and the overall safety rating of coal impoundments because of its improved ability to foresee potential hazards. Further analysis of this technology to include a more refined procedure as well as a means to meet the federal requirement of obtaining mine official signatures should be considered for industrial preparation.

 

​Phase 1 Final Report

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Subtask 3.1 Geomorphic Design: Final Report

John Quaranta, Harold Russell, Nathan DePriest, Alison Sears, & Thomas Wachtel, WVU

 

Approximately 40% of operating mines in West Virginia are surface mines, producing around 50 million tons of coal each year (WV Office of MHS&T, 2011). Federal regulations that have been designed to control environmental impacts associated with surface mining are becoming increasingly stringent. The West Virginia Department of Environmental Protection (WVDEP) Division of Mining and Reclamation and United States Environmental Protection Agency (EPA) recently have delayed or temporarily suspended surface mining permits because of the implementation of more rigorous standards relating to reclamation and post-mining land use. As the demand for energy continues to increase, there is a need to find an alternative to the typical surface mine reclamation techniques used today in Appalachia.

 

The short-term outcome of this project was to assess the feasibility of coal companies to implement geomorphic design into surface mine reclamation in Appalachia. Many other considerations were studied throughout the duration of this project. Laws and regulations were also evaluated to determine where geomorphic design may be applied in Appalachian surface mining. With regulations becoming more stringent and changing frequently, implementing geomorphic ideas into the steep terrain of Appalachia while adhering to current regulations is a challenge.

 

The long-term outcome of this research was to incorporate Carlson’s Natural Regrade^® with GeoFluv™ software to create a geomorphic design for a sample surface mine in southern West Virginia. This followed with evaluation of the conceptual landforms with seepage and slope stability analysis to determine the safety, constructability, and long-term performance of the proposed site.

 

While this innovative reclamation design approach has been used with success in semi-arid regions of the United States, as well as throughout the world, the approach has not been utilized in West Virginia. One main purpose of this project was to analyze the effectiveness of 3 geomorphic reclamation on surface mines in West Virginia as well as a comparison of the features of the completed geomorphic valley-fill design contrasted to an approximate original contour variance valley-fill design. By creating a geomorphic reclamation design for a site in West Virginia, data could be collected and compared directly to traditional designs in order to determine and assess advantages and disadvantages of implementing this innovative surface reclamation technique in Appalachia.

 

A safety analysis as well as a cost analysis was also performed to compare both a traditional valley-fill design and the completed geomorphic valley-fill design so that any significant cost increases or decreases could be assessed. Stream analysis including the length of original streams, length of created streams, stream classification, and stream type was performed to identify complete drainage systems. All of the numerous aspects that were analyzed between the traditional and geomorphic valley-fill designs in return yielded an accurate analysis of the benefits and/or disadvantages of the nontraditional reclamation approach as well as the ability to implement this geomorphic reclamation design method in West Virginia. Following the comparison, it was found that the AOC variance valley-fill design was intended to ensure slope stability, control drainage, complement the drainage pattern of the surrounding terrain, and prevent stream sedimentation.

 

​Subtask 3.1: Final Report

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Appendix B: Soil Analysis and Subsequent Slope Stability Analysis of Geomorphic Landform Profiles Versus Approximate Original Contour Applied to Valley Fill Designs

John Quaranta, WVU

 

This report presents the findings of geotechnical testing on two material types retrieved from a surface mine site in Logan County, West Virginia, and investigates geomorphic landform design as an alternative in lieu of typical valley fill design and AOC surface mine reclamation design. Laboratory testing was carried out according to ASTM standard test methods. The scope of the testing performed involved grain size distribution analysis, hydrometer analysis, saturated shear strength testing under an in situ consolidation load, Atterberg limits including plastic and liquid limits, compaction at three predetermined compaction energies, and rigid wall permeameter hydraulic conductivity testing. Data was evaluated and analyzed to find to what degree the material particles moved under certain hydraulic gradients and if the particle movement affected the shear strength of the samples. The objectives of the testing were to understand the movement of small diameter soil particles at a valley fill and ensure an efficient, durable slope design using deterministic and sensitivity factor of safety analysis on several modules of GeoStudio™.

 

The computational modeling involved geomorphic design for a proposed valley fill in southern West Virginia using commercial software following the Geofluv® method. A comprehensive seepage and slope stability analysis was then developed using the SEEP/W, SIGMA/W, and SLOPE/W modules of GeoStudio2007 for assessing the groundwater flow characteristics of the fill rock, a deformation analysis, and the resultant limit equilibrium analysis of slope stability (factor of safety). These analyses were performed for both the AOC and geomorphic fill designs.

 

For the numerical modeling of the slope stability analysis, it was found that the height of the piezometric line had a profound influence on the factors of safety. When an area was saturated, the factor of safety decreased, sometimes below 1.0 as in the piez. 2 toe scenario of the AOC valley fill design. If the piezometric line was not elevated to the area of the selected failure plane, then the factor of safety remained unchanged. Additionally, steeper slope angles decreased factors of safety. Two initial saturation conditions were modeled for the cumulative analysis. The saturation conditions were applied in SEEP/W, and SIGMA/W computed in situ stresses to be input into SLOPE/W for a factor of safety computation. The initial saturation condition of the gravity segregated durable rock underdrain was significant. The initial saturation altered the volume of water retained within the structure, and ultimately altered the factors of safety that resulted. The factors of safety vary from one hydraulic condition to the next, but did not necessarily increase or decrease accordingly. The result is an effect of the varying areas of increased pore pressure. The result of the SEEP/W analysis produced outputs that accumulated water storage within each fill in different areas, which resulted in varying factors of safety. Both cumulative analysis that were run for the geomorphic design and the valley fill proved that the initial condition could vary the factor of safety. The change in the factor of safety was not always in favor of either condition from a structural standpoint. The significance of the initial saturation condition was that the water storage areas within the fill changed, and altered the factors of safety.

 

The cumulative analysis for the geomorphic valley fill alternative design yielded the highest factors of safety. Most cases produced factors of safety over 2.0. The most likely reason for these high factors of safety is that the geomorphic design had shallower slopes, and drained well. Geomorphic landform design can be utilized to reduce infiltration volumes by shortening runoff travel distances, increasing runoff water removal from a design site. A completed design should retain less water than the modeled results show because of vegetative cover and quick surface runoff. Both initial saturated and unsaturated conditions yielded high factors of safety. The failure locations were sought out to find the lowest factors of safety for the structure. The geomorphic landform profile described in section 13.4 still retained its structural integrity even when high volumes of water are being stored within it. None of the factors of safety even under the most critical circumstances tested yielded factors of safety under 1.0 for the geomorphic design. Even though the original ground dimensions vary for the two profiles, the surface dimensions are identical except for the near the toe. The results prove that the geomorphic design can remain very stable under different conditions and geometries.

 

Sometimes, in an effort to “tie in” boundary elevations with water channel elevations, GeoFluv™ generates slopes that are not structurally sound. One such slope was analyzed, and it was found that it was by far the weakest structure addressed in the numerical modeling. It was referred to as the “critical slope.” None of the factors of safety under any scenario analyzed for the critical slope yielded a factor of safety over 1.0. The factors of safety of this structure were expected to be low. The analysis of the critical slope was intended to illustrate that GeoFluv^® does not consider slope stability, and can produce slopes that are not stable. GeoFluv^® does enable the designer to alter many components of the design to mitigate the slope stability problems that may occur due to rapid elevation changes.

 

The AOC design was typical with its bench cuts and planar slopes. Regulations require that slope factors of safety must remain above 1.3. The analysis performed showed that the design could withstand in situ loads and slope angle under most conditions analyzed. Elevated pore pressures tended to result at the toe of the slope, and decreased the factor of safety. The most critical scenario was a totally saturated toe which yielded a factor of safety of 0.50 as shown in the piez. 2 toe AOC valley fill design model summary in Table 13.24.

 

The SEEP/W analysis yielded results that implied that the structure drained well for the AOC valley fill design. There were small areas of water storage accumulation and elevated pore water pressures, but nothing which caused the factor of safety to drop below 1.0 for the cumulative analysis. For the cumulative analysis, the lowest factor of safety for the AOC valley fill design was 1.22 at the toe of the slope at an initially unsaturated durable rock underdrain condition.

Geomorphic design decreases erosion potential and therefore decreases maintenance demands. The proposed AOC design would be adequate if it remained sufficiently drained. If particle transport can occur and alter toe pore pressures, it is possible that some small slope failure may occur. The gradations that were found for the unweathered well graded sand with silt fill material showed that particle transport would not be a significant concern.

 

​Task 3.1: Appendix B

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Appendix A: The Integration of Geomorphic Design into West Virginia Surface Mine Reclamation

John Quaranta, WVU

 

Concerns of detrimental environmental impacts originating from mountaintop surface mining and valley-fill construction are of constant debate, resulting in a plethora of lawsuits (e.g. Hasselman, 2002, Davis and Duffy, 2009) and scientific studies throughout Appalachia (e.g. Hartman et al., 2005; Pond et al., 2008; Ferrari et al., 2009). State and Federal regulations have been promulgated to control environmental impacts associated with mountaintop mining and valley-fill construction through the Surface Mining Control and Reclamation Act (SMCRA) and the Clean Water Act (CWA). West Virginia has primacy of the State’s regulatory enforcement and thus must meet stringent regulatory standards for valley-fill construction.

 

These regulations have resulted in geotechnically stable designs of valley-fills with runoff management. However, major environmental concerns have resulted, specifically the loss of headwater stream length, increased flooding risk, and degraded water quality in communities downstream. The predicted headwater stream loss in West Virginia is approximately 3,200 km by 2012, thus impacting the ability of West Virginia to support high quality and unique aquatic species (USEPA, 2005). Studies have shown that streams located below valley-fills often have elevated conductivity levels, resulting from water contact with the overburden (Hartman et al., 2005; Pond et al., 2008). Additionally, changes in thermal regime, chemistry, and sedimentation are potential impacts for streams below valley-fills (USEPA, 2005). One promising innovative technique used to lessen these impacts involves fluvial geomorphic landform design that incorporates mature landform shapes into the designs. These landform designs add variability and aid in establishing a site with a long-term hydrologic balance.

 

The work discussed in this report incorporates landforming into the traditional valley-fill design process, thus providing an alternative to the conventional reclamation techniques. The objectives of this research were to:

 

• Use an Appalachian surface mine site to evaluate valley-fill design options.

• Perform a geomorphic landform design using Carlson^'s Natural Regrade^® with GeoFluv™ and landforming principles.

• Compare the geomorphic landform design outputs with the conventional approximate original contour valley-fill design outputs.

 

An alternative reclamation design was created and evaluated to determine if an effective and implementable valley-fill could be designed using Carlson’s Natural Regrade^® software following the Geofluv™ method as applied to mountainous terrain in the central Appalachian region of West Virginia.

 

​Task 3-1: Appendix A

 

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Subtask 3.1 Geomorphic Design: Geotechnical Laboratory Report

Harrold Russell, Leslie Hopkinson, John Quaranta, WVU

 

This paper presents the findings of geotechnical testing performed on two soil material types retrieved from a surface mine site in Logan County, West Virginia. Testing was carried out according to ASTM standard test methods. The scope of the testing performed involved grain size distribution, direct shear strength testing, and hydraulic conductivity testing. Data was evaluated and analyzed to find to what degree the material particles moved under certain hydraulic gradients and if the particle movement affected the shear strength of the samples. The objectives of the testing were to understand the movement of small diameter soil particles at a valley fill and ensure an efficient, durable slope design.

 

Movement of soil particles by storm water runoff supplemented by gravity can change the strength of a slope. It has been found that movement of large volumes of small diameter soil particles can cause slope failure. Increased pore pressures at the toe of a slope due to an accumulation of these small soil particles under a saturated condition can be a significant concern in the slope stability analysis of valley fills.

 

​Subtask 3.1: Geotechnical Laboratory Report

 

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Incorporating Fluvial Geomorphic Landform Approaches for Valley-Fill Design in West Virginia

Alison Sears, Harrold Russell, Leslie Hopkinson, John Quaranta, WVU

 

State and Federal regulations directing mine reclamation using the Approximate Original Contour approach have resulted in geotechnically stable designs of valley fills constructed using waste rock overburden. Environmental concerns at mountain top mining sites abound because of the loss of headwater stream length and increased flooding risk. One promising technique to lessen the impacts involves fluvial geomorphic landform design applied to the waste rock fill and slope profiles. Geomorphic designs have proven successful in semi-arid regions; however, this approach has not been adapted to eastern surface mining reclamation. Research results are presented using fluvial geomorphic design principles which show alternative valley fill design approaches for a mountain top mine site under construction in southern West Virginia. Features of the design are the channelizing of surface water from the rock fill flats and sloped faces, and directing the runoff to engineered perimeter channels.

 

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Comparison of Groundwater Seepage Modeling in Approximate Original Contour and Geomorphic Valley Fill Design

Nathan DePriest, John Quaranta, Leslie Hopkinson, Paul Ziemkiewicz, WVU

 

Excess spoil generated during surface mining in southern West Virginia is generally placed in headwater valleys. Known as valley fills, these structures are designed to move water rapidly through constructed drains to maximize geotechnical stability using the conventional design method termed Approximate Original Contour (AOC). Seepage from valley fills tend to be elevated with respect calcium, magnesium, alkalinity and sulfates and there is evidence that, in high concentrations, these ions can contribute to stream degradation. New fluvial geomorphic principals are being researched to aid in reclamation alternatives to AOC designs. Geomorphic designs have proven successful in semi-arid regions; however, there has been little research performed into the application of this approach for eastern surface mining reclamation.

 

This research investigated the differences in seepage quality and quantity between the AOC method and geomorphic designs on a permitted valley fill in southern West Virginia. The computational modeling involved geomorphic design for a proposed valley fill in southern West Virginia using commercial software. A comprehensive seepage analysis was then developed using a finite element method numerical model for assessing the groundwater flow characteristics of the fill rock for a 10 year time period. This analysis was performed for both the AOC and geomorphic fill designs.

 

Differences in seepage for the AOC and geomorphic fill were presented and discussed as a comparison of the two designs. Analysis criteria were chosen as a way to compare the results of the two fills in order to investigate if an advantage for one fill design was apparent. If an advantage of one fill was apparent, the magnitude of the advantage was quantified using a percent change in results. The results project that higher water velocities (decreased residence times) through mine spoil reclaimed according to the geomorphic fill design. Shorter hydraulic transit times through the spoil are expected to result in lower ionic concentrations in discharge water.

 

 

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