TECHNICAL MEASURES FOR THE INVESTIGATION AND MITIGATION OF FUGITIVE METHANE HAZARDS IN AREAS OF COAL MINING Office of Surface Mining Reclamation and Enforcement Appalachian Regional Coordinating Center Pittsburgh, PA September 2001 Kenneth K. Eltschlager, Mining Engineer, OSM Jay W. Hawkins, Hydrologist, OSM William C. Ehler, Geologist, OSM Fred Baldassare, Hydrogeologist, PA DEP PREFACE Explosive levels of methane are occasionally a problem near or in homes, wells, and other structures. The methane can be generated or liberated from active or abandoned underground mining that is occurring or has occurred underneath or adjacent to these structures. The methane may also come from other sources such as oil wells, gas wells, wetlands, landfills, and septic systems. The Office of Surface Mining Reclamation and Enforcement (OSM) recognizes that hazardous situations may occasionally be caused by current or past coal mining. Methane is not specifically regulated under the Surface Mining Control and Reclamation Act of 1977 (Act). However, the Act at Section 521(a)(2) states that “When... any condition or practices exist which condition, practice, or violation also creates an imminent danger to the health and safety of the public the secretary shall immediately order a cessation of surface coal mining and reclamation operations or the portion thereof relevant to the condition, practice, or violation.” Methane at explosive levels is an imminent danger. Thus, when methane related to active coal mining causes an imminent harm situation, OSM or the State regulatory authority has the responsibility to act. The Act also addresses abandoned mine lands (AML) at Section 410(a): “ The Secretary is authorized to expend moneys from the fund for the emergency restoration, reclamation, abatement, control, or prevention of adverse effects of coal mining practices... if...(1) an emergency exists constituting a danger to the public health, safety, or general welfare...” Methane accumulation in or near homes from abandoned mines can pose a safety risk and therefore warrants action. Other Federal and State agencies may have comparable responsibilities. However, little compiled literature exists on how to determine when methane levels pose an imminent harm or safety problem or on how to locate the source. This document gathers, summarizes, and references the literature to facilitate future methane evaluations. OSM provides this manual as a public service. While the primary target guidance of this document is government scientists, geologists, and engineers, it should also be helpful to the public and industry representatives. Glenda Owens Acting Director PURPOSE Fugitive methane is the uncontrolled release of methane into the atmosphere. It may create an imminent harm to the public or private property. Ultimately, methane should not be allowed to accumulate to explosive levels in wells or structures. This document outlines testing and evaluation protocols for methane in wells, dwellings and soils near coal mines and recommends when action is prudent to prevent or mitigate methane accumulation. These technical guidelines to evaluate fugitive methane are established to: T evaluate the scope of the problem, T define investigative procedures, T develop sampling protocols, T assess hazard potential, and T delineate potential mitigation techniques. Disclaimer Nothing in this manual is a substitute for thoughtful and thorough investigative procedures in circumstances involving a potentially serious methane problem. This manual is intended to provide guidance regarding methane and is solely for the benefit of the users. No duties, rights, or benefits, substantive or procedural, are created or implied by this manual. The contents of this manual are not enforceable by any person or entity against the Office of Surface Mining Reclamation and Enforcement or the United States. Acknowledgments This document was compiled under the guidance of the Methane Work Group. The group was convened by OSM and comprised the following members: Tim Dieringer (Co-Chairman) OSM Kenneth K. Eltschlager (Co-Chairman) OSM Jay W. Hawkins OSM Willam C. Ehler OSM Lois Uranowski OSM John Craynon OSM Fred Baldassare Pennsyvania Department of Environmental Protection Jay Winter Pennsyvania Department of Environmental Protection Lynn Haynes Virginia Department of Mined Land Reclamation JoAnn Erwin West Virginia Department of Environmental Protection Rick Chancellor Wyoming Department of Environmental Quality Lowell Braxton Utah Department of Natural Resources Edward Miller Mine Safety and Health Administration Jim Ulery National Institute for Occupational Safety and Health The following individuals donated their time to peer review parts or all of the manual: Peter J Hutchinson, The Hutchinson Group, Ltd. R. J. Porter Environmental Monitoring, Inc. Dennis D. Coleman Isotech Laboratories, Inc. Jack C. Pashin Geologic Survey of Alabama Dan T. Chafin U. S. Geological Survey OSM wishes to thank the participants for the time and effort spent in compiling this document. TABLE OF CONTENTS SECTION I CHARACTERISTICS AND OCCURRENCE OF METHANE 1.0 INTRODUCTION ....................................................5 2.0 GAS CHARACTERISTICS ............................................7 2.1..............................................................7 2.2 Physical Properties of Gases ......................................8 2.3 Methane Gas Properties .........................................12 3.0 HAZARDOUS EFFECTS OF METHANE ................................14 3.1 Explosive Gases ...............................................15 3.2 Toxic gases ..................................................17 3.3 Asphyxiant Gases .............................................18 4.0 GEOLOGIC ENVIRONMENT OF METHANE ...........................18 4.1 Methane Storage ..............................................20 4.2 Migration Pathways ............................................21 4.3 Coalbed Lithology .............................................22 4.4 Methane in Coal ...............................................23 5.0 FUGITIVE METHANE SOURCES .....................................25 5.1 Gas Wells and Transmission Lines ................................25 5.2 Landfills .....................................................25 5.3 Coal Mines ...................................................25 6.0 HAZARD POTENTIAL .............................................31 6.1 Preliminary Assessment of Potential Hazard .........................31 6.2 Comprehensive Assessment of Potential Hazard: .....................32 6.3 Post-Mitigation Assessment .....................................33 SECTION II ACTION LEVELS FOR METHANE CONCENTRATIONS 1.0 INTRODUCTION ...................................................34 2.0 ATMOSPHERIC METHANE ..........................................35 2.1 Explosibility of Methane Mixtures ................................35 2.2 Regulatory Standards for Methane in Atmospheres ...................35 2.3 Literature on Methane Levels in the Atmosphere ....................36 2.4 Recommended Action Levels - Atmospheric ........................36 3.0 METHANE IN WATER ..............................................37 3.1 Explosibility of Methane in Water ................................37 3.2 Literature on Methane in Water ..................................38 3.3 Regulatory Standards for Dissolved Methane in Water ................40 3.4 Recommended Action Levels - Methane in water ....................40 4.0 METHANE IN SOILS ................................................40 4.1 Explosibility of Methane in the Vadose Zone .......................40 4.2 Literature Search ..............................................41 4.3 Reference regulatory standards for methane in vadose zone .............41 SECTION III INVESTIGATIVE PROCEDURES 1.0 INTRODUCTION ...................................................49 2.0 PRELIMINARY INVESTIGATION ....................................49 2.1 Test for Atmospheric Methane ...................................50 2.2 Interview the Land Owner/Tenant .................................51 2.3 Observe Site Conditions ........................................52 2.4 Action .......................................................53 3.0 COMPREHENSIVE INVESTIGATION .................................53 3.1 Historical Information/Data ......................................53 3.2 Detailed Site Reconnaissance ....................................54 3.3 Field Measurements and Sampling ................................56 4.0 SOURCING OF METHANE ..........................................65 4.1 Gas Wells ....................................................67 4.2 Collection, Transmission, and Distribution Lines .....................67 4.3 Landfills .....................................................68 4.4 Abandoned Mines .............................................69 4.5 Active Mines .................................................70 SECTION IV PROTOCOL FOR METHANE SAMPLING AND GAS ANALYSIS TECHNIQUES 1.0 INTRODUCTION ...................................................72 2.0 TESTING FOR ATMOSPHERIC METHANE ............................72 2.1 Portable Equipment ............................................72 2.2 Sample Containers .............................................74 2.3 Laboratory Equipment ..........................................75 2.4 Sampling Methodology - Atmospheric Methane ......................75 3.0 TESTING FOR METHANE IN WELLS .................................76 3.1 Portable Equipment ............................................77