Document Type: EA-Administrative Record Index Field: Environmental Assessment Project Name: Gallatin Bottom Ash Process Dewatering EA Project Number: 2016-21 GALLATIN FOSSIL PLANT BOTTOM ASH PROCESS DEWATERING FACILITY FINAL ENVIRONMENTAL ASSESSMENT Sumner County, Tennessee Prepared by: TENNESSEE VALLEY AUTHORITY Chattanooga, Tennessee July 2017 To request further information, contact: Ashley R. Farless, PE, AICP NEPA Compliance Tennessee Valley Authority 1101 Market Street Chattanooga, TN 37402 E-mail: [email protected] This page intentionally left blank Table of Contents Table of Contents CHAPTER 1 - PURPOSE OF AND NEED FOR ACTION ................................................................ 1-1 1.1 Introduction and Background ................................................................................................ 1-1 1.2 Purpose and Need ................................................................................................................ 1-5 1.3 Decision to be Made ............................................................................................................. 1-6 1.4 Related Environmental Reviews and Consultation Requirements ....................................... 1-6 1.5 Scope of the Environmental Assessment ............................................................................. 1-6 1.6 Public and Agency Involvement ............................................................................................ 1-7 1.7 Necessary Permits or Licenses ............................................................................................ 1-7 CHAPTER 2 - ALTERNATIVES ........................................................................................................ 2-1 2.1 Description of Alternatives .................................................................................................... 2-1 2.1.1 Alternative A – No Action ................................................................................................ 2-1 2.1.2 Alternative B – Construction of a Bottom Ash Process Dewatering Facility Utilizing a Continuous or “Once Through” System ........................................................ 2-1 2.1.3 Alternative C – Construction of a Bottom Ash Dewatering Facility with a Recirculated Bottom Ash Effluent Stream ..................................................................... 2-2 2.1.4 Alternatives Considered but Eliminated From Further Consideration ............................ 2-3 2.1.4.1 Alternative D – Under-Boiler Bottom Ash Removal System .................................... 2-3 2.1.4.2 Alternative E – Mechanical Removal Using Excavators in Settling Tanks .............. 2-3 2.1.4.3 Alternative F - Dry Boiler Bottom Conversion .......................................................... 2-4 2.2 Comparison of Alternatives ................................................................................................... 2-4 2.3 Identification of Mitigation Measures ..................................................................................... 2-5 2.3.1 Air Quality ....................................................................................................................... 2-5 2.3.2 Surface Water and Groundwater .................................................................................... 2-6 2.4 Preferred Alternative ............................................................................................................. 2-6 CHAPTER 3 - AFFECTED ENVIRONMENT AND ENVIRONMENTAL CONSEQUENCES ................................................................................................................ 3-1 3.1 Air Quality .............................................................................................................................. 3-1 3.1.1 Affected Environment ..................................................................................................... 3-1 3.1.2 Environmental Consequences........................................................................................ 3-2 3.1.2.1 Alternative A – No Action ......................................................................................... 3-2 3.1.2.2 Alternative B – Construction of a Bottom Ash Process Dewatering Facility Utilizing a Continuous or “Once Through” System ...................................... 3-2 3.1.2.3 Alternative C – Construction of a Bottom Ash Dewatering Facility with a Recirculated Bottom Ash Effluent Stream ............................................................... 3-3 3.2 Climate Change .................................................................................................................... 3-3 3.2.1 Affected Environment ..................................................................................................... 3-3 3.2.2 Environmental Consequences........................................................................................ 3-4 3.2.2.1 Alternative A – No Action ......................................................................................... 3-4 3.2.2.2 Alternative B – Construction of a Bottom Ash Process Dewatering Facility Utilizing a Continuous or “Once Through” System ...................................... 3-5 3.2.2.3 Alternative C – Construction of a Bottom Ash Dewatering Facility with a Recirculated Bottom Ash Effluent Stream ............................................................... 3-5 3.3 Vegetation ............................................................................................................................. 3-5 3.3.1 Affected Environment ..................................................................................................... 3-5 3.3.2 Environmental Consequences........................................................................................ 3-8 3.3.2.1 Alternative A – No Action ......................................................................................... 3-8 Final Environmental Assessment i Table of Contents 3.3.2.2 Alternative B – Construction of a Bottom Ash Process Dewatering Facility Utilizing a Continuous or “Once Through” System ...................................... 3-8 3.3.2.3 Alternative C – Construction of a Bottom Ash Dewatering Facility with a Recirculated Bottom Ash Effluent Stream ............................................................... 3-8 3.4 Wildlife ................................................................................................................................... 3-8 3.4.1 Affected Environment ..................................................................................................... 3-8 3.4.2 Environmental Consequences...................................................................................... 3-10 3.4.2.1 Alternative A – No Action ....................................................................................... 3-10 3.4.2.2 Alternative B – Construction of a Bottom Ash Process Dewatering Facility Utilizing a Continuous or “Once Through” System .................................... 3-11 3.4.2.3 Alternative C – Construction of a Bottom Ash Dewatering Facility with a Recirculated Bottom Ash Effluent Stream ............................................................. 3-11 3.5 Aquatic Ecology .................................................................................................................. 3-12 3.5.1 Affected Environment ................................................................................................... 3-12 3.5.2 Environmental Consequences...................................................................................... 3-13 3.5.2.1 Alternative A – No Action ....................................................................................... 3-13 3.5.2.2 Alternative B – Construction of a Bottom Ash Process Dewatering Facility Utilizing a Continuous or “Once Through” System .................................... 3-14 3.5.2.3 Alternative C – Construction of a Bottom Ash Dewatering Facility with a Recirculated Bottom Ash Effluent Stream ............................................................. 3-14 3.6 Threatened and Endangered Species ................................................................................ 3-14 3.6.1 Affected Environment ................................................................................................... 3-14 3.6.1.1 Species Descriptions.............................................................................................. 3-16 3.6.2 Environmental Consequences...................................................................................... 3-19 3.6.2.1 Alternative A – No Action ....................................................................................... 3-19 3.6.2.2 Alternative B – Construction of a Bottom Ash Process Dewatering Facility Utilizing a Continuous or “Once Through” System .................................... 3-19 3.6.2.3 Alternative C – Construction of a Bottom Ash Dewatering Facility with a Recirculated Bottom Ash Effluent Stream ............................................................. 3-20 3.7 Surface Water and Wastewater .......................................................................................... 3-20 3.7.1 Affected Environment ................................................................................................... 3-20 3.7.2 Environmental Consequences...................................................................................... 3-24 3.7.2.1 Alternative A – No Action ......................................................................................