Level 3 Stormwater Treatment Engineering Report Northwest Container Services–Seattle Intermodal Yard 635 South Edmunds Street Seattle, Washington King County Site Operator: Northwest Container Services, Inc Permit Number: WAR-301360 Permit Type: Industrial Stormwater General Permit Prepared by: PBS Engineering and Environmental Inc. 415 W 6th Street, Suite 601 Vancouver, Washington 98660 May 11, 2018 PBS Project 17645.005 415 W 6 TH STREET, SUITE 601 VANCOUVER, WA 98660 3 60. 695. 3488 MAIN 866.727.0140 FAX PBSUSA.COM Level 3 Stormwater Treatment Engineering Report Northwest Container Services – Seattle Intermodal Yard Northwest Container Services, Inc. Seattle, Washington TABLE OF CONTENTS Industrial Stormwater General Permit S8.D.3.a References ........................................................................................................ iii General Information ................................................................................................................................................................................... iv 1 INTRODUCTION .............................................................................................................................................. 1 2 FACILITY ASSESSMENT .................................................................................................................................. 2 2.1 Facility Description .................................................................................................................................................................... 2 2.2 Surface Water Drainage .......................................................................................................................................................... 2 3 TREATMENT ALTERNATIVE EVALUATION................................................................................................... 4 3.1 Water Quality Characterization ............................................................................................................................................ 4 3.2 Hydrologic Analysis .................................................................................................................................................................. 4 3.3 Treatment Alternatives ............................................................................................................................................................ 5 3.3.1 Alternatives 1.A, 1.B, and 1.C .................................................................................................................................. 5 3.3.2 Alternative 1.D .............................................................................................................................................................. 6 3.3.3 Alternative 1.E ............................................................................................................................................................... 6 3.3.4 Alternative 1.F ............................................................................................................................................................... 7 3.3.5 Alternative 2.A .............................................................................................................................................................. 7 3.3.6 Alternative 2.B .............................................................................................................................................................. 7 3.3.7 Alternative 2.C .............................................................................................................................................................. 8 3.4 Treatment Alternative Expected Performance ............................................................................................................... 8 3.5 Estimated Preliminary Cost Estimates ............................................................................................................................. 12 4 PROPOSED STORMWATER SYSTEM IMPROVEMENTS ............................................................................ 15 4.1 Selected Treatment BMP and Sizing Calculations ...................................................................................................... 15 4.2 Treatment Process and Operation .................................................................................................................................... 15 4.3 Use of Chemicals in the Treatment Process .................................................................................................................. 16 4.4 Expected Treatment Performance..................................................................................................................................... 16 5 CERTIFICATION BY A LICENSED PROFESSIONAL ENGINEER ................................................................... 19 May 11, 2018 i PBS Project 17645.005 Level 3 Stormwater Treatment Engineering Report Northwest Container Services – Seattle Intermodal Yard Northwest Container Services, Inc. Seattle, Washington SUPPORTING DATA TABLES Table 1: Water Quality Characterization of Seattle Intermodal Yard Stormwater (Q3 2015 - Q2 2017) Table 2. Selected Design Flow Rates for Drainage Basin 1 and 2 Table 3. Summary of Projected Pollutant Reduction for Drainage Basin 1 Alternative 1.A Table 4. Summary of Projected Pollutant Reduction for Drainage Basin 1 Alternative 1.B Table 5. Summary of Projected Pollutant Reduction for Drainage Basin 1 Alternative 1.C Table 6. Summary of Projected Pollutant Reduction for Drainage Basin 1 Alternative 1.D Table 7. Summary of Projected Pollutant Reduction for Drainage Basin 1 Alternative 1.E Table 8. Summary of Projected Pollutant Reduction for Drainage Basin 1 Alternative 1.F Table 9. Summary of Projected Pollutant Reduction for Drainage Basin 2 Alternative 2.A Table 10. Summary of Projected Pollutant Reduction for Drainage Basin 2 Alternative 2.B Table 11. Summary of Projected Pollutant Reduction for Drainage Basin 2 Alternative 2.C Table 12. Treatment Technology Estimated Preliminary Cost Estimates Table 13. Summary of Projected Pollutant Reduction for the Proposed Drainage Basin 1 Treatment System Table 14. Summary of Projected Pollutant Reduction for the Proposed Drainage Basin 2 Treatment System FIGURES Figure 1. Vicinity Map Figure 2. Site Map: South Rail Strip Figure 3. Site Map: Main Yard Figure 4. Site Map: North Rail Strip North of Snoqualmie Figure 5. Site Map: North Rail Strip South of Industrial Way Figure 6. Plan View: Proposed Drainage Basin 1 Treatment System Figure 7. Plan View: Proposed Drainage Basin 2 Treatment System Figure 8. Flow Diagram: Proposed Drainage Basin 1 Treatment System Figure 9. Flow Diagram: Proposed Drainage Basin 2 Treatment System APPENDICES Appendix A: Conceptual Designs for Drainage Basin 1 Alternatives Appendix B: Conceptual Designs for Drainage Basin 2 Alternatives Appendix C: Western Washington Hydrology Model Results Appendix D: Contech Provided Studies ©2018 PBS Engineering and Environmental Inc. May 11, 2018 ii PBS Project 17645.005 Level 3 Stormwater Treatment Engineering Report Northwest Container Services – Seattle Intermodal Yard Northwest Container Services, Inc. Seattle, Washington Industrial Stormwater General Permit S8.D.3.a References S8.D.3.a The Engineering Report must include: Report Section i. Brief summary of the treatment alternatives considered and why the proposed option was Sections 3.3, 3.4, and selected. Include cost estimates of ongoing operation and maintenance, including disposal of 3.5 any spent media; ii. The basic design data, including characterization of stormwater influent, and sizing Sections 3.1, 3.2, and calculations of the treatment units; 4.1 iii. A description of the treatment process and operation, including a flow diagram; Section 4.2 iv. The amount and kind of chemicals used in the treatment process, if any. Note: use of Section 4.3 stormwater treatment chemicals requires submittal of Request for Chemical Treatment Form; v. Results to be expected from the treatment process including the predicted stormwater Sections 3.4 and 4.4 discharge characteristics; vi. A statement, expressing sound engineering justification through the use of pilot plant data, results from similar installations, and/or scientific evidence that the proposed treatment is Section 4.4 and 5 reasonably expected to meet the permit benchmarks; and vii. Certification by a licensed professional engineer. Section 5 May 11, 2018 iii PBS Project 17645.005 Level 3 Stormwater Treatment Engineering Report Northwest Container Services – Seattle Intermodal Yard Northwest Container Services, Inc. Seattle, Washington General Information Name of Facility: Northwest Container Services – Seattle Intermodal Yard Location of Facility: 635 South Edmunds Street Seattle, Washington 98108 Type of Facility: Intermodal Container Transfer Station Primary SIC Code 4013 (Railroad Switching and Terminal Establishments) Secondary SIC Code: 4731 (Arrangement of Transportation of Freight and Cargo) Primary NAICS 488210 (Support Activities for Rail Transportation) Secondary NAICS 488510 (Freight Transportation Arrangement) Type of Permit: Industrial Stormwater – General Permit Permit Number: WAR-301360 County: King County Site Area: 620,400 square feet (14.2 acres) Impervious Area: 620,400 square feet (14.2 acres) Chief Official: Gary Cardwell Title: Division Vice President Site Contact Name: Nate Beffert Site Contact Title: