ENVIRONMENTAL PROTECTION AT THE MANAGED SOLID WASTE LANDFILL Prepared by: 10220 Old Columbia Road, Suite A Columbia, Maryland 21046 Document No. MD10186 29 MARCH 2010 This page intentionally left blank Geosyntec Consultants TABLE OF CONTENTS ACKNOWLEDGEMENTS AND DISCLAIMER ................................................................. 1 DEFINITIONS AND LIST OF ACRONYMS ..................................................................... 2 EXECUTIVE SUMMARY ................................................................................................ 4 1. OVERVIEW OF A MANAGED SOLID WASTE LANDFILL ..................................... 15 1.1 What is a Managed Solid Waste Landfill? ............................................................. 17 1.2 Key Elements of a Managed Solid Waste Landfill ................................................ 17 1.3 How is Environmental Performance Monitored? ...................................................... 19 1.4 What Happens Inside a Managed Solid Waste Landfill? .................................... 21 1.4.1 Treatment (Biodegradation) of Solid Waste .............................................. 21 1.4.2 Permanent Storage of Biogenic Carbon in Landfills (Sequestration) ..... 24 1.4.3 Development of a Leachate Biofilter in Bottom-Most Waste Layers ..... 24 1.4.4 Physical and Biogenic Settlement ................................................................. 25 2. REGULATORY OVERSIGHT OF MANAGED SOLID WASTE LANDFILLS .............. 26 2.1 Overview of Solid Waste Landfill Regulations ....................................................... 27 2.2 Regulatory Obligations though the Life of a Landfill ............................................. 27 2.2.1 Siting Considerations ....................................................................................... 28 2.2.2 Planning and Design ........................................................................................ 28 2.2.3 Construction ....................................................................................................... 29 2.2.4 Operation and Maintenance ......................................................................... 30 2.2.5 Environmental and Performance Monitoring and Reporting .................... 30 2.2.6 Closure ............................................................................................................... 31 2.2.7 Long-Term Maintenance and Post-Closure Care ....................................... 32 2.3 Public Involvement in the Permitting Process ............................................................ 33 3. DESIGN COMPONENT SYSTEMS OF A MANAGED SOLID WASTE LANDFILL .... 34 3.1 Containment of Waste in Landfills ............................................................................. 34 3.2 Liner System.................................................................................................................... 36 3.2.1 Liner System Components ............................................................................... 37 3.2.2 Key Environmentally Protective Features of Liner Systems ...................... 38 3.2.3 Long-Term Performance of Liner Systems ................................................... 38 3.3 Leachate Management System ................................................................................... 39 3.3.1 Leachate Collection and Recovery System ................................................. 39 MD10186.doc i 29 March 2010 Geosyntec Consultants TABLE OF CONTENTS (continued) 3.3.2 Key Environmentally Protective Features of Leachate Collection Systems ............................................................................................................................ 40 3.3.3 Long-Term Performance and Longevity of Leachate Collection Systems ............................................................................................................................ 41 3.3.4 Leachate Management Options .................................................................... 41 3.4 Landfill Cover Systems ................................................................................................. 44 3.4.1 Design of Final Cover Systems ...................................................................... 45 3.4.2 Key Environmentally Protective Features of Final Cover Systems .......... 47 3.4.3 Long-Term Performance of Final Cover Systems ....................................... 47 3.5 Gas Management System ........................................................................................... 50 3.5.1 Active Landfill Gas Management ................................................................. 50 3.5.2 Passive Landfill Gas Management ............................................................... 51 3.5.3 Key Environmentally Protective Features of Gas Control Systems ......... 53 3.5.4 Long-Term Performance of Gas Management Systems ........................... 53 3.6 The Role of Managed Landfills in Controlling Greenhouse Gases ...................... 54 3.6.1 Landfill Gas Collection Efficiency ................................................................. 55 3.6.2 Methane Oxidation in Cover Soils ............................................................... 56 3.6.3 Carbon Sequestration ..................................................................................... 56 4. OPERATION AND MAINTENANCE OF A MANAGED SOLID WASTE LANDFILL 58 4.1 Management of Landfill Operations ......................................................................... 59 4.1.1 Landfill Infrastructure and Equipment .......................................................... 59 4.1.2 Landfill Supervision and Operator Training ............................................... 59 4.2 Landfill Operation under Permit Conditions ............................................................. 60 4.2.1 Compliance with the Facility Operating Plan ............................................. 61 4.2.2 Waste Screening ............................................................................................. 62 4.2.3 Daily Operation at the Working Face ........................................................ 62 4.2.4 Stormwater Management .............................................................................. 63 4.3 Maintenance of Landfill Systems ................................................................................ 65 4.3.1 Preventative and Response Maintenance during Active Operations ..... 65 4.3.2 Post-Closure Maintenance .............................................................................. 67 5. ENVIRONMENTAL MONITORING AT MANAGED SOLID WASTE LANDFILLS.... 68 5.1 Why Monitor for Potential Releases from a Landfill to the Environment? .......... 69 MD10186.doc ii 29 March 2009 Geosyntec Consultants TABLE OF CONTENTS (continued) 5.2 Components of an Environmental Monitoring Program .......................................... 69 5.2.1 Groundwater Monitoring System .................................................................. 70 5.2.2 Surface Water Monitoring Program ............................................................ 71 5.2.3 Subsurface Gas Migration Monitoring System ........................................... 71 5.2.4 Surface Emissions Monitoring ......................................................................... 72 5.2.5 Monitoring the Performance of Landfill Operational Systems ................ 73 6. THE SAFETY OF THE MODERN LANDFILL .......................................................... 75 6.1 Performance-Based Landfill Design and Management ......................................... 76 6.1.1 Overlapping Systems for Landfill Operation ............................................. 76 6.1.2 Predictability in Landfill Performance Trends ............................................ 77 6.2 Providing Long-Term Landfill Integrity ...................................................................... 78 6.2.1 Responding to Minor Upsets of Landfill Operational Systems ................ 78 6.2.2 The Potential for Extensive Landfill Failure ................................................. 78 6.2.3 Performance-Based Maintenance and Ending Care at Closed Landfills ............................................................................................................................ 80 6.3 Environmentally Protective Landfill Designs ............................................................. 81 7. BEYOND WASTE CONTAINMENT – LANDFILLS AS A RESOURCE ..................... 89 7.1 Landfill Gas-to-Energy and Other Proactive Green Energy Opportunities ...... 89 7.2 Effective Sequestration of Carbon in Landfills ........................................................ 91 7.3 Enhanced Waste Treatment vs. Waste Containment .............................................. 92 7.4 Increased Beneficial End Use Options for Closed Landfill Properties ................. 94 8. REFERENCES ..................................................................................................... 96 APPENDICES APPENDIX A: LONG-TERM BEHAVIOR OF MANAGED LANDFILLS A1. OVERVIEW ....................................................................................................... 105 A1.1 Degradation of Waste in Landfills ......................................................................... 105 A1.2 Regulatory Background ............................................................................................ 107 A1.3 Organization of this Appendix ...............................................................................