City of Seattle Major Public Project Construction Noise Variance Application SR 520/I-5 Express Lanes Connection Project Prepared for Washington State Department of Transportation Lead Author Ginette Lalonde WSP USA June 23, 2019 Major Public Project Construction Noise Variance Application Table of Contents Introduction ............................................................................................................................................. 1 Project Descriptions and Proposed Construction Activities ...................................................................... 3 SR 520/I-5 Project Overview and Project Site Description ................................................................... 3 Expected Construction Activities ......................................................................................................... 7 SDOT Compliance with City of Seattle Criteria for a Major Public Project Construction Noise Variance .................................................................................................................................................. 9 Definition of Major Public Project ....................................................................................................... 9 SMC 25.08.168: The Definition of a Major Public Project ............................................................... 9 SMC 23.84A.030 “P”: The Definition of Public Facility .................................................................. 9 Criteria for Granting a Noise Variance ................................................................................................. 9 SMC 25.08.590.C: The Criteria for Granting a Noise Variance ........................................................ 9 Criteria for a Major Public Project Construction Noise Variance ........................................................ 10 SMC 25.08.655.A: The Criteria for an MPPCNV........................................................................... 10 How Does This Project Meet the Criteria for an MPPCNV? ........................................................... 10 WSDOT Term of Proposed Variance ................................................................................................. 13 SMC 25.08.655.B: The Term of the Proposed Variance ................................................................. 13 Characteristics of Sound and Noise ........................................................................................................ 17 Definition of Sound ........................................................................................................................... 17 Definition of Noise ........................................................................................................................ 17 Noise Level Descriptors ................................................................................................................. 18 City of Seattle Noise Control Ordinance ................................................................................................ 19 Exceptions to the Seattle Noise Control Ordinance ............................................................................. 19 Proposed Nighttime Noise Level Limits ............................................................................................. 20 Noise Management and Mitigation Plan ................................................................................................ 21 Expected Noisiest Nighttime Construction Periods............................................................................. 21 WSDOT Noise Modeling Summary ...................................................................................................... 23 SR 520/I-5 Project – Create Access and Work Space Impact Activities .............................................. 23 SR 520/I-5 Project – Retaining Walls Demolition Impact Activities ................................................... 26 SR 520/I-5 Project – Shaft Construction ............................................................................................. 28 SR 520/I-5 Project – Structural Steel Girder ....................................................................................... 30 SR 520/I-5 Project – Retaining Wall Construction ............................................................................. 32 Proposed Noise Mitigation Measures ................................................................................................. 35 Required Minimum Mitigation Measures ....................................................................................... 35 Additional Noise-Control Measures ............................................................................................... 36 Compliance Monitoring and Reporting .............................................................................................. 36 Public Outreach and Community Involvement ................................................................................... 39 Written Materials ........................................................................................................................... 39 In-person Public Engagement Activities ............................................................................................. 39 Online and Electronic Communications ............................................................................................. 39 Media Relations and Social Media ..................................................................................................... 40 Conclusion ............................................................................................................................................ 41 SR 520 Bridge Replacement and HOV Program i City of Seattle Exhibits Exhibit 1. SR 520/I-5 Project Area........................................................................................................... 5 Exhibit 2. Zoning .................................................................................................................................... 6 Exhibit 3. Estimated Schedule of SR 520/I-5 Project Nighttime Construction Activities ........................... 8 Exhibit 4. Construction Area and Noise Measurement and Modeled Locations ...................................... 15 Exhibit 5. Measured Hourly Average Baseline Noise Levels and Proposed Exterior Nighttime Noise Level Limits ............................................................................................................ 15 Exhibit 6. Measured Lmax Noise Levels and Proposed L1 Exterior Nighttime Indicator Noise Levels ............................................................................................................................... 16 Exhibit 7. Perceived Loudness Increases ................................................................................................ 17 Exhibit 8. Typical Noise Levels ............................................................................................................. 18 Exhibit 9. Seattle Noise Control Ordinance – Exterior Sound Level Limits ............................................ 19 Exhibit 10. Nighttime Construction Equipment Typical Noise levels ..................................................... 22 Exhibit 11. Exterior Nighttime Access and Work Space Noise Levels .................................................... 23 Exhibit 12. Create Access and Work Space ............................................................................................ 24 Exhibit 13. Create Access and Work Space Zoomed .............................................................................. 25 Exhibit 14. Exterior Nighttime Demolition of Retaining Walls Noise Levels.......................................... 26 Exhibit 15. Demolition of Retaining Walls ............................................................................................ 27 Exhibit 16. Exterior Nighttime Shaft Construction ................................................................................. 28 Exhibit 17. Shaft Construction ............................................................................................................... 29 Exhibit 18. Exterior Nighttime Structural Steel Girder Erection ............................................................. 30 Exhibit 19. Structural Steel Girder ......................................................................................................... 31 Exhibit 20. Exterior Nighttime Retaining Wall Construction .................................................................. 32 Exhibit 21. Retaining Wall Construction Noise Level Contours ............................................................. 33 Exhibit 22. Retaining Wall Construction Noise Level Contours Zoomed................................................ 34 Exhibit 23. Reporting Structure For Non-Compliance ............................................................................ 38 Attachments Attachment 1: Noise Management and Mitigation Plan Attachment 2: Project Area and Notification Area ii SR 520 Bridge Replacement and HOV Program Major Public Project Construction Noise Variance Application Acronyms and Abbreviations ANSI American National Standards Institute dB Decibels dBA A-weighted decibels HOV High-occupancy vehicle Hz Hertz INM Independent Noise Monitor L1 Sound level exceeded for 1 percent of the measurement duration (i.e., 36 seconds per hour) Leq Equivalent sound level Lmax Maximum noise level MPPCNV Major Public