Lead Agency United States Department of Agriculture Draft Rural Utilities Service Engineering and Environmental Staff Environmental 1400 Independence Avenue S.W. Room 2244, Washington D.C. 20250-1571 Assessment Bromley to Prairie Center 115-kV Transmission Line Project Tri-State Generation and Transmission Association, Inc. February 2014 Bromley-Prairie Center 115-kV Transmission Line Project Draft Environmental Assessment Prepared by: U.S. Department of Agriculture, Rural Utilities Service Engineering and Environmental Staff 1400 Independence Avenue S.W. Room 2244 Washington D.C. 20250-1571 Tri-State Generation and Transmission Association, Inc. 1100 West 116th Avenue Westminster, Colorado 80234 February 2014 TABLE OF CONTENTS 1.0 PROJECT OVERVIEW ............................................................................................... 1-1 1.1 Introduction ................................................................................................................. 1-1 1.2 Regulatory Process ..................................................................................................... 1-1 1.2.1 Federal ................................................................................................................... 1-4 1.2.2 State ....................................................................................................................... 1-5 1.2.3 County and City ...................................................................................................... 1-5 1.2.4 Private Ownership .................................................................................................. 1-5 1.3 Purpose and Need ...................................................................................................... 1-5 1.3.1 Redundant Service ................................................................................................. 1-6 1.3.2 Increased Capacity ................................................................................................. 1-6 1.3.3 Regulatory Standards ............................................................................................. 1-6 2.0 PROJECT DESCRIPTION .......................................................................................... 2-1 2.1 Project Alternatives ..................................................................................................... 2-1 2.1.1 Proposed Action ..................................................................................................... 2-1 2.1.2 Alternative A ........................................................................................................... 2-1 2.1.3 Alternative B ........................................................................................................... 2-2 2.1.4 No Action Alternative .............................................................................................. 2-2 2.1.5 Alternatives Considered but Eliminated ................................................................. 2-2 2.1.5.1 Alternative Line Routes .................................................................................. 2-2 2.1.5.2 Underground 115-kV Construction ................................................................ 2-2 2.2 Project Description ...................................................................................................... 2-4 2.2.1 Proposed 115-kV Transmission Line ..................................................................... 2-4 2.2.2 Right-of-Way Requirements ................................................................................... 2-6 2.2.3 Access Routes ....................................................................................................... 2-6 2.2.4 Project Construction ............................................................................................... 2-6 2.2.5 Operation and Maintenance ................................................................................... 2-9 2.2.6 Environmental Protection Measures ...................................................................... 2-9 3.0 AFFECTED ENVIRONMENT ...................................................................................... 3-1 3.1 Air Quality .................................................................................................................... 3-1 3.1.1 Proposed Action ..................................................................................................... 3-1 3.1.2 Alternative A ........................................................................................................... 3-1 3.1.3 Alternative B ........................................................................................................... 3-1 3.2 Geology and Minerals ................................................................................................. 3-2 3.2.1 Proposed Action ..................................................................................................... 3-2 3.2.2 Alternative A ........................................................................................................... 3-3 3.2.3 Alternative B ........................................................................................................... 3-3 3.3 Soils ............................................................................................................................ 3-3 3.3.1 Proposed Action ..................................................................................................... 3-6 3.3.2 Alternative A ........................................................................................................... 3-6 3.3.3 Alternative B ........................................................................................................... 3-6 3.4 Water Resources......................................................................................................... 3-6 3.4.1 Proposed Action ..................................................................................................... 3-8 3.4.2 Alternative A ........................................................................................................... 3-8 3.4.3 Alternative B ........................................................................................................... 3-8 3.5 Floodplains .................................................................................................................. 3-8 3.5.1 Proposed Action ..................................................................................................... 3-8 3.5.2 Alternative A ........................................................................................................... 3-8 3.5.3 Alternative B ........................................................................................................... 3-9 Draft Bromley-Prairie Center EA i February 2014 TABLE OF CONTENTS, CONTINUED 3.6 Wetlands ..................................................................................................................... 3-9 3.6.1 Proposed Action ..................................................................................................... 3-9 3.6.2 Alternative A ......................................................................................................... 3-15 3.6.3 Alternative B ......................................................................................................... 3-16 3.7 Vegetation Resources ............................................................................................... 3-17 3.7.1 Proposed Action ................................................................................................... 3-17 3.7.1.1 Vegetation .................................................................................................... 3-17 3.7.2 Alternative A ......................................................................................................... 3-19 3.7.2.1 Vegetation .................................................................................................... 3-19 3.7.3 Alternative B ......................................................................................................... 3-20 3.7.3.1 Vegetation .................................................................................................... 3-20 3.8 Wildlife Resources..................................................................................................... 3-21 3.8.1 Proposed Action ................................................................................................... 3-21 3.8.2 Alternative A ......................................................................................................... 3-27 3.8.3 Alternative B ......................................................................................................... 3-27 3.9 Special Status Species.............................................................................................. 3-30 3.9.1 Proposed Action ................................................................................................... 3-31 3.9.1.1 Plants ............................................................................................................ 3-31 3.9.1.2 Animals ......................................................................................................... 3-32 3.9.2 Alternative A ......................................................................................................... 3-35 3.9.2.1 Plants ...........................................................................................................