ANALYSIS OF THE CHANGES IN THE OPERATIONAL STRUCTURES AND SAFETY MEASURES OF U.S. UNDERGROUND COAL MINES ACROSS DIFFERENT MINE-SIZE CATEGORIES, 2000-2014

Open Access
Author:
Eslambolchi, Safa
Graduate Program:
Energy and Mineral Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
August 18, 2016
Committee Members:
  • Jeremy M. Gernand, Dissertation Advisor
  • Jeremy M. Gernand, Committee Chair
  • Seth Blumsack, Committee Member
  • Shimin Liu, Committee Member
  • Matthew Reimherr, Outside Member
Keywords:
  • Underground Coal Mine
  • Mine size
  • Policy Analysis
  • Safety Measures
  • Stochastic Processes
  • Economic Analysis
Abstract:
Significant driving pressures, such as electricity market conditions, and safety and environmental laws, regulations, and policies can impact the operational structure and viability of the underground coal mining industry. Environmental Protection Agency’s (EPA) actions in pursuit of clean air resulted in the retirement of several coal-fired power plants. Recent fatal underground coal mine disasters have resulted in stricter safety regulations, elevated penalties, and mine shutdowns. The objective of this study is to understand the changes in the operational structure and safety measures of U.S. underground coal mines across different mine-size categories during the period 2000-2014. The changes in the operational structures of the mines were studied by examining the year-to-year changes in the mine-size and operational status categories during the period 2000-2014. The differences in three normalized safety measures, Non-fatal Days Lost Incident Rates (NFDLIRs), No-days Lost Incident Rates (NDLIRs), and Severity Measures (SMs), were examined across different mines-size categories over the periods 2005-2009 and 2010-2014. For this study, large amount of empirical data were collected from the Mine Safety and Health Administration’s (MSHA) Address/Employment and Accident/Injury files, and Assessed Violations datasets as well as Energy Information Administration’s (EIA) reports for the period 2000-2014. The size of a mine can change from one year to another because of various reasons, such as, temporary or permanent mine closure, planned increases or decreases in production, or mine depletion. The sizes of the mines were determined in each year based on the average number of employees working in the mines as well as the production of the mines. The number of mines in each mine-size category in each year were determined. Year-to-year mine-size transition probabilities were calculated and fourteen 8x8 right-stochastic mine-size transition probability matrices were created. Size-stability, size-decrease, and size-increase probabilities for each mine-size category for each year-to-year transition time period were calculated too. The total number of underground mines decreased by almost 43% from 2000 to 2014. The number of the Very Large mines increased by 20% from 2009 to 2014. The number of the Large mines and the Medium mines decreased by 22% and 40%, respectively, from 2012 to 2014. The number of the Small and Very Small mines almost steadily decreased by 59.5% and 55.6%, respectively, from 2008 to 2014. On average, the Very Large and Large mines with size-stability probabilities of 0.937 and 0.767, respectively, were found to be the most resilient mines followed by the Medium, Small, and Very Small mines with the size-stability probabilities of 0.611, 0.565, and 0.544, respectively. Mine-size transitions of two or more sizes up or down transitions, which were rare and usually were associated with probabilities of less than 5% were noted as “unusual” mine-size transitions. The larger mines (Very Large and Large mines) were found to be more resilient in adapting to the driving pressures affecting the industry. The status of a mine can change from one year to another because of various reasons such as, temporary or permanent mine shut downs, which can be a voluntary or involuntary decision of the mine operator. It is important to understand the dynamics of mine status changes to avoid involuntarily mine shut downs when possible. The operational status of the mines in each year were determined along with the changed in the operational statuses of the mines from one year to another. Year-to-year transition probabilities of the mines were calculated showing the probability of the mines transitioning within seven operation statuses. The results show that the total number of Active mines dramatically decreased by 52.4% from 544 in 2000 to 259 in 2014. The majority of the decrease occurred after 2010 from 508 Active mines to 259 in 2014. The majority of the decreases occurred in the number of Medium, Small, and Very Small mines. On average, an Active mine would remain Active in the next year with a probability of 77.6% while it would be Closed by MSHA, Permanently Abandoned, or Temporality Closed with probabilities of 11.4%, 6.8%, and 2.6%, respectively. Also, Temporarily Closed mines would remain closed the next year with the probability of 71.3% and would be Permanently Abandoned with a probability of 20.7%. The Normalized safety performance measures (NDLIR, NFDLIR, and SM) of the Active underground coal mines were calculated and studied across five mine-size categories, Very Large, Large, Medium, Small, and Very Small, over the periods 2005-2009 and 2010-2014. For each safety performance measure, the Mann-Whitney U tests were done across the five different mine- size categories to test the differences in the observations from the first period to the next. The NDLIRs of Large and Medium mines were found to be lower in the second period compared to the first period. Both NFDLIRs and SMs of the Very Large, Large, Medium, and Small mines were found to be lower in the second period compared to the first period. Statistically no differences were found in the NDLFIRs and SMs of Very Small mines from the first period to the second period. Moreover, the NFDLIR means for each mine-size category were much larger than their corresponding NDLIR means. A drastic decrease of more than 50% in the severity measure mean of Small mines in the second period was observed which can be attributed to the closure of several small mines during that period. Overall, we can conclude that the safety measures of the Very Large, Large, Medium, and Small mines were significantly lower in the period 2010-2014 compared to 2005-2009. Size matters. The results of this research showed that conducting analyses across different mine-size categories could yield to different results compared to when analyzing all the mines in one pool. The sizes of the mines should be taken into account when developing new laws, regulations, or policies concerning underground coal mines. This research may help the MSHA and other state agencies in developing more effective regulations and policies, which take into account the size of the underground coal mining operations.