Document Type: EA-Administrative Record Index Field: Environmental Assessment Project Name: TVA System Operations Center and Power System Supply Project Number: 2019-1 TVA SYSTEM OPERATIONS CENTER AND POWER SYSTEM SUPPLY FINAL ENVIRONMENTAL ASSESSMENT Bradley, Hamilton, and Meigs Counties, Tennessee Prepared by: TENNESSEE VALLEY AUTHORITY Chattanooga, Tennessee February 2020 Direct Comments to: Anita E. Masters NEPA Program Tennessee Valley Authority 1101 Market Street, BR 2C Chattanooga, Tennessee 37402 This page intentionally left blank Contents TABLE OF CONTENTS CHAPTER 1 – PURPOSE AND NEED FOR ACTION ......................................................................... 1 1.1 Proposed Action – Address the Current Physical and Reliability Risks Present in the Existing System Operations Center .................................................................. 1 1.2 Need for the Proposed Action .................................................................................................. 4 1.2.1 Physical Risks .................................................................................................................... 5 1.2.2 Reliability Risks .................................................................................................................. 7 1.3 Decisions to be Made ............................................................................................................... 8 1.4 Related Environmental Reviews or Documentation ................................................................. 8 1.5 Scoping Process and Public Involvement ................................................................................ 9 1.6 Issues to be Addressed .......................................................................................................... 13 1.7 Public and Agency Involvement ............................................................................................. 14 1.8 Necessary Permits and Licenses ........................................................................................... 14 CHAPTER 2 – ALTERNATIVES INCLUDING THE PROPOSED ACTION ...................................... 15 2.1 Alternatives ............................................................................................................................. 15 2.1.1 Alternative A: The No Action Alternative ......................................................................... 15 2.1.2 Alternative B – TVA Constructs a New Standalone System Operations Control Center, Gunstocker Creek 161-kV Substation, and Associated 161-kV Transmission Line .............................................................................................. 16 2.1.3 Alternatives Considered but Eliminated from Further Discussion ................................... 17 2.1.3.1 The ROC Becomes Primary Control Center/SOC Becomes Backup (Option 1) .................................................................................................................. 17 2.1.3.2 Retrofit COC for New SOC Space (Option 2) ........................................................... 17 2.1.3.3 Underground Utility Lines .......................................................................................... 18 2.2 Initial SOC Siting Study .......................................................................................................... 18 2.2.1 Definition and Description of the Study Area ................................................................... 18 2.2.2 Data Collection ................................................................................................................ 20 2.2.3 Establishment and Application of Siting Criteria .............................................................. 20 2.3 Transmission Line Siting Process .......................................................................................... 25 2.3.1 Consider Potential Substation Location ........................................................................... 25 2.3.2 Determine Existing Transmission Line Power Source to Proposed Substation ....................................................................................................................... 25 2.3.2.1 Option One: Sequoyah-Watts Bar Hydro 161-kV TL ................................................ 25 2.3.2.2 Option Two: Sequoyah-Nuclear Plant–Hiawassee No. 1 161-kV TL ........................ 26 2.3.3 Characterization of Transmission Line Project Area ....................................................... 27 2.3.3.1 Transportation ........................................................................................................... 27 2.3.3.2 Natural Areas and Cultural Features......................................................................... 27 2.3.3.3 Land Use ................................................................................................................... 28 2.3.4 Siting Tools Utilized ......................................................................................................... 29 2.3.5 Route Development and Public Information Day ............................................................ 29 2.3.6 Finalization of Substation Location and Transmission Line Route .................................. 31 2.4 Construction, Operation, and Maintenance of the Proposed System Operations Center and Substation ......................................................................................... 35 2.4.1 SOC Property Acquisition, Clearing and Development ................................................... 35 2.4.2 SOC and Substation Site Preparation and Infrastructure ................................................ 36 2.5 Construction, Operation, and Maintenance of the Proposed Transmission Line ......................................................................................................................................... 38 2.5.1 Transmission Line Construction ...................................................................................... 38 Environmental Assessment i TVA System Operations Center and Power System Supply 2.5.1.1 Right-of-Way Acquisition and Clearing ..................................................................... 38 2.5.1.2 Access Roads ........................................................................................................... 39 2.5.1.3 Construction Assembly Areas ................................................................................... 40 2.5.1.4 Structures and Conductors ....................................................................................... 40 2.5.1.5 Conductor and Ground Wire Installation ................................................................... 41 2.5.2 Operation and Maintenance ............................................................................................ 41 2.5.2.1 Inspection .................................................................................................................. 41 2.5.2.2 Vegetation Management ........................................................................................... 41 2.5.2.3 Structure Replacement ............................................................................................. 42 2.6 Comparison of Environmental Effects by Alternative ............................................................. 42 2.7 Identification of Mitigation Measures ...................................................................................... 46 2.8 The Preferred Alternative ....................................................................................................... 48 CHAPTER 3 – AFFECTED ENVIRONMENT AND ENVIRONMENTAL CONSEQUENCES ................................................................................................................. 49 3.1 Air Quality ............................................................................................................................... 49 3.1.1 Affected Environment ...................................................................................................... 49 3.1.2 Environmental Consequences......................................................................................... 50 3.1.2.1 Alternative A – The No Action Alternative ................................................................. 50 3.1.2.2 Alternative B – TVA Constructs a New Standalone SOC, Gunstocker Creek 161-kV Substation, and Associated 161-kV Transmission Line ..................................................................................................... 50 3.2 Groundwater and Geology ..................................................................................................... 51 3.2.1 Affected Environment ...................................................................................................... 51 3.2.2 Environmental Consequences......................................................................................... 52 3.2.2.1 Alternative A – The No Action Alternative ................................................................. 52 3.2.2.2 Alternative B – TVA Constructs a New Standalone SOC, Gunstocker Creek 161-kV Substation, and Associated 161-kV Transmission Line ..................................................................................................... 52 3.3 Soils and Prime Farmland ...................................................................................................... 52 3.3.1 Affected Environment .....................................................................................................