United States Department of the Interior Office of Surface Mining Reclamation and Enforcement Environmental Assessment Dry Fork Mine Amendment 3 Federal Mining Plan Modification September 2019 Prepared by: U.S. Department of the Interior Office of Surface Mining Reclamation and Enforcement Program Support Division 1999 Broadway, Suite 3320 Denver, CO 80202 PH: 303-293-5000 / FAX: 303-293-5032 TABLE OF CONTENTS 1.0 Purpose and Need ................................................................................................ 1-1 1.1 Introduction .................................................................................................................................... 1-1 1.2 Background ..................................................................................................................................... 1-1 1.3 Purpose and Need ........................................................................................................................ 1-5 1.4 Relationship to Statutes, Regulations, and Other Agency Plans ......................................... 1-6 1.5 Public Outreach and Issues ......................................................................................................... 1-6 2.0 Proposed Action and Alternatives ..................................................................... 2-1 2.1 Description of Alternatives ......................................................................................................... 2-1 2.2 Existing Conditions (Conditions Common to the Proposed Action and the No Action Alternative) ....................................................................................................................... 2-3 3.0 Affected Environment .......................................................................................... 3-1 3.1 General Setting .............................................................................................................................. 3-1 3.2 Topography and Physiography ................................................................................................... 3-1 3.3 Geology, Minerals, and Paleontology ........................................................................................ 3-1 3.4 Air Quality and Climate Change ................................................................................................ 3-2 3.5 Water Resources ........................................................................................................................ 3-10 3.6 Alluvial Valley Floors (AVFs) ..................................................................................................... 3-15 3.7 Wetlands/Aquatic Features ....................................................................................................... 3-15 3.8 Soils ................................................................................................................................................ 3-16 3.9 Vegetation ..................................................................................................................................... 3-16 3.10 Wildlife .......................................................................................................................................... 3-17 3.11 Land Use and Recreation .......................................................................................................... 3-19 3.12 Cultural Resources ..................................................................................................................... 3-21 3.13 Visual Resources .......................................................................................................................... 3-21 3.14 Noise .............................................................................................................................................. 3-21 3.15 Transportation Facilities ............................................................................................................ 3-21 3.16 Hazardous and Solid Wastes .................................................................................................... 3-21 3.17 Socioeconomics ........................................................................................................................... 3-21 4.0 Environmental Consequences/Cumulative Effects ........................................... 4-1 4.1 Introduction .................................................................................................................................... 4-1 4.2 Topography and Physiography .................................................................................................... 4-2 Dry Fork Mine A3 EA i TABLE OF CONTENTS (Cont.) 4.3 Geology, Mineral Resources, and Paleontology ...................................................................... 4-3 4.4 Air Quality and Climate Change ................................................................................................ 4-4 4.5 Water Resources ........................................................................................................................ 4-17 4.6 Alluvial Valley Floors .................................................................................................................. 4-23 4.7 Wetlands/Aquatic Features ....................................................................................................... 4-23 4.8 Soil .................................................................................................................................................. 4-24 4.9 Vegetation ..................................................................................................................................... 4-25 4.10 Wildlife .......................................................................................................................................... 4-26 4.11 Land Use and Recreation ........................................................................................................... 4-30 4.12 Cultural Resources ..................................................................................................................... 4-30 4.13 Noise .............................................................................................................................................. 4-31 4.14 Visual Resources .......................................................................................................................... 4-32 4.15 Transportation Facilities ............................................................................................................ 4-33 4.16 Hazardous and Solid Waste ...................................................................................................... 4-34 4.17 Socioeconomics ........................................................................................................................... 4-35 4.18 Short-Term Uses and Long-Term Productivity .................................................................... 4-36 4.19 Unavoidable Adverse Effects ..................................................................................................... 4-36 5.0 Consultation and Coordination........................................................................... 5-1 5.1 Public Comment Process ............................................................................................................ 5-1 5.2 Preparers and Contributors ....................................................................................................... 5-1 5.3 Distribution of the EA .................................................................................................................. 5-1 6.0 References and Abbreviations/Acronyms .......................................................... 6-1 6.1 References ...................................................................................................................................... 6-1 6.2 Abbreviations/Acronyms ............................................................................................................. 6-9 LIST OF TABLES Table 2-1. Summary Comparison of Coal Production, Surface Disturbance, Mine Life, and Employees for the Current Permit No. PT0599, the No Action Alternative, and the Proposed Action, as of December 31, 2018 ............................ 2-1 Table 2-2. Mine Life Scenarios for the Proposed Action ................................................................ 2-2 Table 2-3. Summary of Phased Bond Release Acreages associated with the Proposed Action ..................................................................................................................................... 2-6 th Table 3-1. Measured NO2 Concentrations (98 Percentile 1-Hour NO2 Concentrations, in ppb) at Selected AQS Monitoring Sites, 2012-2018 ................. 3-3 Dry Fork Mine A3 EA ii TABLE OF CONTENTS (Cont.) th Table 3-2. Measured O3 Concentrations (4 -Highest 8-hour Maximum Value, in ppm) at Selected AQS Monitoring Sites, 2012-2018 .............................................................. 3-5 Table 3-3. Measured SO2 Concentrations in Campbell County, Wyoming th (99 Percentile, 1-Hour SO2 Concentrations in ppb) at a Selected AQS Monitoring Site, 2012-2018 ............................................................................................... 3-5 Table 3-4. Mercury Emissions (Tons) from Power Plants Supplied by DFM, 2012-2017........ 3-5 Table 3-5. Measured Annual Pb Air Emissions from Three Campbell County Power Stations