United States Department of the Interior Office of Surface Mining Reclamation and Enforcement Dry Fork Mine Amendment 2, Tract 1 Federal Mining Plan Modification Environmental Assessment May 2017 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 ..................................................................................................................................... 1-2 1.2.1 Site History ........................................................................................................................... 1-2 1.2.2 Project Background............................................................................................................. 1-6 1.2.3 Statutory and Regulatory Background ............................................................................ 1-7 1.3 Purpose and Need ........................................................................................................................ 1-8 1.3.1 Purpose .................................................................................................................................. 1-8 1.3.2 Need ....................................................................................................................................... 1-8 1.4 Relationship to Statutes, Regulations, and Other Agency Plans ......................................... 1-8 1.4.1 Statutes and Regulations .................................................................................................... 1-8 1.4.2 Other Agency Plans .......................................................................................................... 1-10 1.5 Authorizing Actions .................................................................................................................... 1-11 1.6 Outreach and Issues ................................................................................................................... 1-11 2.0 Proposed Action and Alternatives ..................................................................... 2-1 2.1 DFM WDEQ-LQD Permit .......................................................................................................... 2-1 2.2 Project Area ................................................................................................................................... 2-1 2.3 Description of Existing Mining and Reclamation Operations .............................................. 2-3 2.3.1 Current Bonding and Bond Release Status ................................................................... 2-5 2.3.2 DFM Support Facilities ....................................................................................................... 2-6 2.4 Description of Alternatives ......................................................................................................... 2-6 2.4.1 Proposed Action .................................................................................................................. 2-7 2.4.1.1 Mine Operation Components within the Project Area Associated with the Proposed Action .............................................................................................................. 2-8 2.4.1.2 Existing and Proposed Disturbance within the Project Area ................................ 2-8 2.4.1.3 Mining Operations Associated with the Proposed Action ..................................... 2-9 2.4.2 No Action Alternative ........................................................................................................ 2-9 2.4.3 Alternatives Considered but Eliminated from Further Study ................................. 2-10 2.4.3.1 Underground Mining Alternative ............................................................................... 2-10 2.4.3.2 Low or No Pollutant Emitting Equipment ................................................................ 2-11 2.4.3.3 Air Quality Mitigation Alternatives ............................................................................ 2-11 Dry Fork Mine A2Tr1 EA i TABLE OF CONTENTS (Cont.) 2.4.4 Project Environmental Protection and Mitigation Features ..................................... 2-11 2.4.4.1 Topography ..................................................................................................................... 2-12 2.4.4.2 Air Quality ....................................................................................................................... 2-12 2.4.4.3 Water Resources ........................................................................................................... 2-12 2.4.4.4 Vegetation ........................................................................................................................ 2-13 2.4.4.5 Terrestrial Wildlife ........................................................................................................ 2-13 2.4.4.6 Fish/Aquatic Life ............................................................................................................. 2-14 2.4.4.7 Threatened and Endangered Species ......................................................................... 2-14 2.4.4.8 Cultural Resources ........................................................................................................ 2-14 2.4.4.9 Visual Resources ............................................................................................................ 2-14 2.4.4.10 Soils ................................................................................................................................... 2-14 2.4.4.11 Post-mining Land Use ................................................................................................... 2-15 3.0 Affected Environment .......................................................................................... 3-1 3.1 General Setting .............................................................................................................................. 3-2 3.2 Topography and Physiography ................................................................................................... 3-2 3.3 Geology, Minerals, and Paleontology ........................................................................................ 3-4 3.3.1 General Geology ................................................................................................................. 3-4 3.3.2 Mineral Resources ............................................................................................................... 3-9 3.3.3 Paleontology ....................................................................................................................... 3-10 3.4 Air Quality .................................................................................................................................... 3-11 3.4.1 National Ambient Air Quality Standards ..................................................................... 3-11 3.4.2 Attainment/Nonattainment Area Designations .......................................................... 3-13 3.4.3 Prevention of Significant Deterioration ........................................................................ 3-14 3.4.4 Best Available Control Technology ............................................................................... 3-15 3.4.5 New Source Performance Standards (NSPS) ............................................................. 3-16 3.4.6 Federal Operating Permit Program ............................................................................... 3-16 3.4.7 Existing DFM Air Quality Summary .............................................................................. 3-16 3.4.7.1 Background .................................................................................................................... 3-16 3.4.7.2 Air Quality-Monitoring Values .................................................................................... 3-16 3.4.7.3 Air Quality Related Values........................................................................................... 3-21 3.4.7.3.1 Visibility ..................................................................................................................... 3-21 3.4.7.3.2 Air Quality Related Values Related to Coal Combustion ............................. 3-21 Dry Fork Mine A2Tr1 EA ii TABLE OF CONTENTS (Cont.) 3.4.7.3.3 Acidification of Lakes/Acid Deposition .............................................................. 3-21 3.4.7.4 Greenhouse Gases (GHG) .......................................................................................... 3-22 3.4.7.5 Emission Standards at Coal Combustion Sources.................................................. 3-23 3.5 Water Resources ........................................................................................................................ 3-26 3.5.1 Surface Water .................................................................................................................... 3-26 3.5.2 Groundwater ...................................................................................................................... 3-29 3.5.2.1 Alluvium ..........................................................................................................................