ALASKAN WAY VIADUCT REPLACEMENT PROJECT Final Environmental Impact Statement APPENDIX B Alternatives Description and Construction Methods Submitted by: PARSONS BRINCKERHOFF Prepared by: PARAMETRIX J U L Y 2 0 1 1 Alaskan Way Viaduct Replacement Project Final EIS Alternatives Description and Construction Methods Discipline Report The Alaskan Way Viaduct Replacement Project is a joint effort between the Federal Highway Administration (FHWA), the Washington State Department of Transportation (WSDOT), and the City of Seattle. To conduct this project, WSDOT contracted with: Parsons Brinckerhoff 999 Third Avenue, Suite 3200 Seattle, WA 98104 In association with: Coughlin Porter Lundeen, Inc. EnviroIssues, Inc. GHD, Inc. HDR Engineering, Inc. Jacobs Engineering Group Inc. Magnusson Klemencic Associates, Inc. Mimi Sheridan, AICP Parametrix, Inc. Power Engineers, Inc. Shannon & Wilson, Inc. William P. Ott Construction Consultants SR 99: Alaskan Way Viaduct Replacement Project July 2011 Alternatives Description and Construction Methods Discipline Report Final EIS This Page Intentionally Left Blank TABLE OF CONTENTS Chapter 1 Introduction and Summary ................................................................................................................. 1 1.1 Introduction ................................................................................................................................................ 1 1.2 Project Background ................................................................................................................................... 1 1.3 Summary ................................................................................................................................................... 2 1.3.1 Construction Plans, Durations, and Sequencing ............................................................................. 3 1.4 Build Alternatives Overview ....................................................................................................................... 3 1.4.1 Elements Common to All Build Alternatives .................................................................................... 4 1.4.2 Bored Tunnel Overview ................................................................................................................... 5 1.4.3 Cut-and-Cover Tunnel Alternative Overview ................................................................................... 8 1.4.4 Elevated Structure Alternative Overview ....................................................................................... 10 1.5 List of Final EIS Appendices .................................................................................................................... 12 Chapter 2 Description of Alternatives ............................................................................................................... 13 2.1 Viaduct Closed (No Build Alternative) ...................................................................................................... 13 2.1.1 Viaduct Closed (No Build Alternative) 2030 Scenario 1: Sudden Unplanned Loss of SR 99 ........ 13 2.1.2 Viaduct Closed (No Build Alternative) 2030 Scenario 2: Catastrophic Failure and Collapse of SR 99 ....................................................................................................................................... 13 2.1.3 2015 Existing Viaduct .................................................................................................................... 14 2.2 Elements Common to All Build Alternatives ............................................................................................ 14 2.2.1 Utility Relocations .......................................................................................................................... 14 2.2.2 Viaduct Removal ........................................................................................................................... 15 2.3 Bored Tunnel Alternative ......................................................................................................................... 16 2.3.1 South Portal Area .......................................................................................................................... 16 2.3.2 Bored Tunnel Alignment – Central ................................................................................................ 21 2.3.3 North Portal Area ........................................................................................................................... 23 2.3.4 Battery Street Tunnel Decommissioning ....................................................................................... 24 2.3.5 Program Elements ......................................................................................................................... 27 2.4 Cut-and-Cover Tunnel Alternative ........................................................................................................... 29 2.4.1 South – S. Royal Brougham Way to S. King Street ....................................................................... 29 2.4.2 Central – S. King Street to South Portal of Battery Street Tunnel ................................................. 32 2.4.3 Battery Street Tunnel – Portal to Portal ......................................................................................... 35 2.4.4 North – Battery Street Tunnel to Aloha Street ............................................................................... 36 2.5 Elevated Structure Alternative ................................................................................................................. 38 2.5.1 South – S. Royal Brougham Way to S. King Street ....................................................................... 38 2.5.2 Central – S. King Street to South Portal of Battery Street Tunnel ................................................. 40 2.5.3 Battery Street Tunnel – Portal to Portal ......................................................................................... 43 2.5.4 North – Battery Street Tunnel to Aloha Street ............................................................................... 43 2.5.5 Pine Street to Broad Street ............................................................................................................ 44 Chapter 3 Construction Elements and Methods .............................................................................................. 45 3.1 Construction Elements Common to All Build Alternatives ....................................................................... 45 3.1.1 Construction Staging Areas ........................................................................................................... 45 3.1.2 Construction Work Shifts ............................................................................................................... 49 3.1.3 Construction Haul Routes .............................................................................................................. 49 3.1.4 Construction Equipment ................................................................................................................ 50 3.1.5 Utility Relocations .......................................................................................................................... 51 SR 99: Alaskan Way Viaduct Replacement Project July 2011 Alternatives Description and Construction Methods Discipline Report i Final EIS 3.1.6 Seattle Ferry Terminal Access During Construction ...................................................................... 52 3.2 Bored Tunnel Alternative – Construction Methods for Major Elements ................................................... 53 3.2.1 Construction Risks and Ground Improvement Methods ................................................................ 53 3.2.2 South Portal Area Construction ..................................................................................................... 59 3.2.3 Bored Tunnel Construction ............................................................................................................ 60 3.2.4 North Portal Area Construction ...................................................................................................... 67 3.2.5 Viaduct Demolition ........................................................................................................................ 68 3.2.6 Battery Street Tunnel Decommissioning ....................................................................................... 69 3.2.7 Surface Street Improvements and Restoration of Utilities ............................................................. 69 3.3 Cut-and-Cover Tunnel Alternative Construction Methods ....................................................................... 70 3.3.1 South – S. Royal Brougham Way to S. King Street ....................................................................... 70 3.3.2 Central – S. King Street to South Portal of Battery Street Tunnel ................................................. 71 3.3.3 North – Battery Street Tunnel to Aloha Street ............................................................................... 72 3.4 Elevated Structure Alternative Construction Methods ............................................................................. 73 3.4.1 South – S. Royal Brougham Way to S. King Street ....................................................................... 74 3.4.2 Central – S. King Street to South Portal of Battery Street Tunnel ................................................