Document Type: EA-Administrative Record Index Field: Final Environmental Assessment Project Name: SHF Dewatering Project Number: 2016-17 SHAWNEE FOSSIL PLANT BOTTOM ASH PROCESS DEWATERING FACILITY FINAL ENVIRONMENTAL ASSESSMENT McCracken County, Kentucky Prepared by: TENNESSEE VALLEY AUTHORITY Chattanooga, TN September 2016 To request further information, contact: Ashley R. Farless, PE, AICP NEPA Compliance Tennessee Valley Authority 1101 Market Street Chattanooga, TN 37402 Phone: 423.751.2361 Fax: 423.751.7011 E-mail: [email protected] This page intentionally left blank Contents Table of Contents CHAPTER 1 – PURPOSE AND NEED FOR ACTION ......................................................................... 1 1.1 Introduction and Background ................................................................................................... 1 1.2 Purpose and Need ................................................................................................................... 1 1.3 Decision to be Made ................................................................................................................ 1 1.4 Summary of Proposed Action .................................................................................................. 3 1.5 Related Environmental Reviews and Consultation Requirements .......................................... 3 1.6 Scope of the Environmental Assessment ................................................................................ 4 CHAPTER 2 – ALTERNATIVES .......................................................................................................... 7 2.1 Description of Alternatives ....................................................................................................... 7 2.1.1 Alternative A – No Action Alternative ................................................................................ 7 2.1.2 Alternative B – Construction/Operation of a Process Dewatering Facility Utilizing a Continuous or “Once Through” System ........................................................... 8 2.1.3 Alternative C – Process Dewatering System with a Recirculated Bottom Ash Sluice Stream.................................................................................................................. 11 2.2 Alternatives Considered But Eliminated From Further Discussion ........................................ 15 2.2.1 Alternative D – Isolation and Separate Processing of Bottom Ash and Pyrite Streams ........................................................................................................................... 15 2.2.2 Alternative E – Dry Boiler Bottom Conversion ................................................................. 15 2.3 Comparison of Alternatives .................................................................................................... 15 2.4 Identification of Mitigation Measures ...................................................................................... 18 2.5 The Preferred Alternative ....................................................................................................... 18 CHAPTER 3 – AFFECTED ENVIRONMENT AND ENVIRONMENTAL CONSEQUENCES ................................................................................................................. 19 3.1 Air Quality ............................................................................................................................... 19 3.1.1 Affected Environment ...................................................................................................... 19 3.1.2 Environmental Consequences......................................................................................... 19 3.1.2.1 Alternative A – No Action Alternative ........................................................................ 19 3.1.2.2 Alternative B – Construction/Operation of a Process Dewatering Facility Utilizing a Continuous or “Once Through” System ................................................................. 19 3.1.2.3 Alternative C – Process Dewatering System with a Recirculated Bottom Ash Sluice Stream ............................................................................................................ 20 3.2 Climate Change ..................................................................................................................... 21 3.2.1 Affected Environment ...................................................................................................... 21 3.2.2 Environmental Consequences......................................................................................... 22 3.2.2.1 Alternative A – No Action Alternative ........................................................................ 22 3.2.2.2 Alternative B – Construction/Operation of a Process Dewatering Facility Utilizing a Continuous or “Once Through” System ................................................................. 22 3.2.2.3 Alternative C – Process Dewatering System with a Recirculated Bottom Ash Sluice Stream ............................................................................................................ 22 3.3 Groundwater and Geology ..................................................................................................... 22 3.3.1 Affected Environment ...................................................................................................... 22 3.3.2 Environmental Consequences......................................................................................... 24 3.3.2.1 Alternative A – No Action Alternative ........................................................................ 24 3.3.2.2 Alternative B – Construction/Operation of a Process Dewatering Facility Utilizing a Continuous or “Once Through” System ................................................................. 24 3.3.2.3 Alternative C – Process Dewatering System with a Recirculated Bottom Ash Sluice Stream ............................................................................................................ 25 Final Environmental Assessment i Shawnee Fossil Plant Dewatering Facility 3.4 Surface Water ........................................................................................................................ 25 3.4.1 Affected Environment ...................................................................................................... 25 3.4.2 Environmental Consequences......................................................................................... 29 3.4.2.1 Alternative A – No Action Alternative ........................................................................ 29 3.4.2.2 Alternative B – Construction/Operation of a Dewatering Facility Utilizing a Continuous or “Once Through” System .................................................................... 29 3.4.2.3 Alternative C – Process Dewatering System with a Recirculated Bottom Ash Sluice Stream ............................................................................................................ 34 3.5 Floodplains ............................................................................................................................. 36 3.5.1 Affected Environment ...................................................................................................... 36 3.5.2 Environmental Consequences......................................................................................... 37 3.5.2.1 Alternative A – No Action Alternative ........................................................................ 39 3.5.2.2 Alternative B – Construction/Operation of a Process Dewatering Facility Utilizing a Continuous or “Once Through” System ................................................................. 39 3.5.2.3 Alternative C – Process Dewatering System with a Recirculated Bottom Ash Sluice Stream ............................................................................................................ 39 3.6 Vegetation .............................................................................................................................. 39 3.6.1 Affected Environment ...................................................................................................... 39 3.6.2 Environmental Consequences......................................................................................... 42 3.6.2.1 Alternative A – No Action Alternative ........................................................................ 42 3.6.2.2 Alternative B – Construction/Operation of a Process Dewatering Facility Utilizing a Continuous or “Once Through” System ................................................................. 42 3.6.2.3 Alternative C – Process Dewatering System with a Recirculated Bottom Ash Sluice Stream ............................................................................................................ 42 3.7 Wildlife .................................................................................................................................... 42 3.7.1 Affected Environment ...................................................................................................... 42 3.7.2 Environmental Consequences......................................................................................... 43 3.7.2.1 Alternative A – No Action Alternative ........................................................................ 43 3.7.2.2 Alternative B – Construction/Operation of a Process Dewatering Facility Utilizing a Continuous or “Once Through”