Final Report I-270 North Environmental Assessment I-70 to the Chain of Rocks Bridge Saint Louis County, Missouri MoDOT Job Number: J6I3020 Prepared for MoDOT – Missouri Department of Transportation Saint Louis Area District 1590 Woodlake Drive Chesterfield, MO 63017 November 2016 Contents Section Page Acronyms and Abbreviations ................................................................................................................. VII Executive Summary ............................................................................................................................. ES-1 Proposed Action ................................................................................................................................. ES-1 Purpose and Need .............................................................................................................................. ES-3 Reasonable Alternatives Considered ................................................................................................. ES-3 Reasonable Alternative #1 .................................................................................................... ES-4 Reasonable Alternative #2 .................................................................................................... ES-4 Summary of Impacts ........................................................................................................................ ES-13 Environmental Commitments .......................................................................................................... ES-13 Public Involvement/Agency Coordination ....................................................................................... ES-14 1 Introduction and Study Overview .............................................................................................. 1-1 1.1 Study Overview ...................................................................................................................... 1-1 1.2 Study Background .................................................................................................................. 1-1 1.3 Study Area Description .......................................................................................................... 1-3 1.4 Configuration of I-270 ............................................................................................................ 1-6 1.4.1 Mainline Corridor ...................................................................................................... 1-6 1.4.2 Crossroads and Pedestrian Facilities ........................................................................ 1-6 1.4.3 Interchanges ............................................................................................................. 1-7 1.4.4 Outer Road System ................................................................................................... 1-8 2 Purpose and Need ..................................................................................................................... 2-1 3 Alternatives Considered ............................................................................................................ 3-1 3.1 Overview of the Alternative Development Process............................................................... 3-1 3.2 Development and Evaluation of Conceptual Alternatives ..................................................... 3-2 3.2.1 Process Used to Develop Conceptual Alternatives ................................................... 3-2 3.2.2 Conceptual Alternatives Not Requiring Complete Rebuild ...................................... 3-3 3.2.3 Conceptual Build Alternatives .................................................................................. 3-4 3.2.4 Evaluation and Screening of the Conceptual Alternatives ....................................... 3-4 3.3 Development and Evaluation of Reasonable Alternatives .................................................... 3-7 3.3.1 Configuration of Reasonable Alternatives ................................................................ 3-8 3.3.2 Performance/Operating Characteristics Summary ................................................. 3-10 3.3.3 Environmental Impact Summary ............................................................................ 3-10 3.3.4 Cost, Public Involvement, and Acquisition Impact Summary ................................. 3-11 3.3.5 Changes from Reasonable Alternatives .................................................................. 3-11 3.3.6 Preferred Alternative Decision-Making Factors ..................................................... 3-11 3.3.7 Preferred Alternative .............................................................................................. 3-16 4 Affected Environment and Impacts ............................................................................................ 4-1 4.1 Air Quality .............................................................................................................................. 4-1 4.1.1 Air Quality — Regulatory Background and Standards .............................................. 4-1 4.1.2 Air Quality — Affected Environment ........................................................................ 4-3 4.1.3 Air Quality — Impacts ............................................................................................... 4-8 4.2 Community Resources ........................................................................................................... 4-9 4.2.1 Community Resources — Regulatory Background and Standards ........................... 4-9 4.2.2 Community Resources — Affected Environment ................................................... 4-10 TR0823161144SCO I CONTENTS 4.2.3 Community Resources — Impacts .......................................................................... 4-14 4.3 Construction Operations ...................................................................................................... 4-15 4.3.1 Construction — Regulatory Background and Standards ........................................ 4-15 4.3.2 Construction — Impacts ......................................................................................... 4-15 4.4 Cultural Resources ............................................................................................................... 4-17 4.4.1 Cultural Resources —Regulatory Background and Standards ................................ 4-17 4.4.2 Cultural Resources — Affected Environment ......................................................... 4-17 4.4.3 Cultural Resources — Impacts ................................................................................ 4-21 4.5 Demographics ...................................................................................................................... 4-24 4.5.1 Demographics — Regulatory Background and Standards ...................................... 4-24 4.5.2 Demographics — Affected Environment ................................................................ 4-24 4.5.3 Demographics — Impacts ....................................................................................... 4-25 4.6 Endangered and Threatened Species .................................................................................. 4-25 4.6.1 Regulatory Background ........................................................................................... 4-25 4.6.2 Affected Environment ............................................................................................. 4-27 4.6.3 Effects of Proposed Action...................................................................................... 4-28 4.7 Environmental Justice .......................................................................................................... 4-31 4.7.1 Environmental Justice — Regulatory Background and Standards .......................... 4-31 4.7.2 Environmental Justice — Affected Environment .................................................... 4-32 4.7.3 Environmental Justice — Impacts ........................................................................... 4-38 4.8 Farmland .............................................................................................................................. 4-44 4.8.1 Farmland — Regulatory Background and Standards .............................................. 4-44 4.8.2 Farmland — Affected Environment ........................................................................ 4-44 4.8.3 Farmland — Impacts ............................................................................................... 4-45 4.9 Geological Setting ................................................................................................................ 4-45 4.9.1 Geological Setting — Regulatory Background and Standards ................................ 4-45 4.9.2 Geological Setting — Affected Environment .......................................................... 4-45 4.9.3 Geological Setting — Impacts ................................................................................. 4-45 4.10 Hazardous Materials ............................................................................................................ 4-49 4.10.1 Hazardous Materials — Regulatory Background and Standards ............................ 4-49 4.10.2 Hazardous Materials — Affected Environment ...................................................... 4-49 4.10.3 Hazardous Materials — Impacts ............................................................................