Summary: Structural Stormwater Controls Science Review and Synthesis Project, SSC Science Review, literature review of structural stormwater controls, science to inform future policy discussions, key findings
Structural Stormwater Controls | Science Review & Synthesis Project
Structural Stormwater Controls
Science Review and Synthesis Project
Final White Paper
Prepared for:
Washington State Department of Ecology
Prepared by:
Aimee S. Navickisâ€Brasch, PhD, PE
Osborn Consulting, Inc.
Maria Peraki, PhD, EIT
Osborn Consulting, Inc.
James Packman
Aspect Consulting
Paul Fendt, PE
Parametrix
Christian Nilsen, PE
Geosyntec Consultants
Taylor Hoffmanâ€Ballard, PE
Osborn Consulting, Inc.
Mark Maurer, PE, PLA
Osborn Consulting, Inc.
Structural Stormwater Controls | Science Review & Synthesis Project
iii
Table of Contents
Executive Summary …………………………………………………………………………………………………………………………………………….. 1
Introduction …………………………………………………………………………………………………………………………………………. 1â€1
1.1
Chapter Purpose and Contents ………………………………………………………………………………………………………… 1â€1
1.2
Overview of Work Completed …………………………………………………………………………………………………………. 1â€1
1.3
Project Purpose ……………………………………………………………………………………………………………………………… 1â€1
1.3.1
Project Background and Goals ………………………………………………………………………………………………….. 1â€1
1.3.2
Additional Goals ……………………………………………………………………………………………………………………… 1â€2
1.3.3
TAC Project Vision …………………………………………………………………………………………………………………… 1â€4
1.4
TAC and Consultant Team Role ………………………………………………………………………………………………………… 1â€5
1.5
White Paper Contents and Organization …………………………………………………………………………………………… 1â€6
1.5.1
Chapter 1. Introduction ……………………………………………………………………………………………………………. 1â€6
1.5.2
Chapter 2. Define Requirements ………………………………………………………………………………………………. 1â€6
1.5.3
Chapter 3. Benefit Questions ……………………………………………………………………………………………………. 1â€6
1.5.4
Chapter 4. Application Questions ……………………………………………………………………………………………… 1â€7
1.5.5
Chapter 5. Conclusion ……………………………………………………………………………………………………………… 1â€7
1.6
Appendices ……………………………………………………………………………………………………………………………………. 1â€8
1.6.1
Appendix 1â€1 TAC Comments and Consultant Responses …………………………………………………………….. 1â€9
Define Requirements, Goals, and Vision …………………………………………………………………………………………………… 2â€1
2.1
Chapter Purpose and Contents ………………………………………………………………………………………………………… 2â€1
2.2
Overview of Work Completed …………………………………………………………………………………………………………. 2â€1
2.3
Relevant Requirements …………………………………………………………………………………………………………………… 2â€1
2.4
Reasoning for Permit Language ……………………………………………………………………………………………………….. 2â€7
2.5
Overview of Jurisdictions SSC Programs ………………………………………………………………………………………….. 2â€10
2.6
References ………………………………………………………………………………………………………………………………….. 2â€17
2.7
Appendices ………………………………………………………………………………………………………………………………….. 2â€21
2.7.1
Appendix 2â€1 – Phase II Screening Questions and Responses ……………………………………………………… 2â€22
2.7.2
Appendix 2â€2 – Interview Questions ………………………………………………………………………………………… 2â€27
2.7.3
Appendix 2â€3 – Interview Responses: Phase I and Phase II …………………………………………………………. 2â€34
2.7.4
Appendix 2â€4 – TAC Comments and Responses to Comments …………………………………………………… 2â€130
Benefit Questions ………………………………………………………………………………………………………………………………….. 3â€1
3.1
Chapter Purpose and Contents ………………………………………………………………………………………………………… 3â€1
3.2
Overview of Work Completed …………………………………………………………………………………………………………. 3â€1
3.3
Literature Search ……………………………………………………………………………………………………………………………. 3â€1
3.3.1
Define Key Terms ……………………………………………………………………………………………………………………. 3â€1
3.3.2
Approach ……………………………………………………………………………………………………………………………….. 3â€3
Structural Stormwater Controls | Science Review & Synthesis Project
3.3.3
Summary of Literature Findings ………………………………………………………………………………………………… 3â€6
3.3.4
Summary of Research Gaps ……………………………………………………………………………………………………… 3â€6
3.4
Responses to Benefit Questions ………………………………………………………………………………………………………. 3â€7
3.4.1
Benefit Question 1 ………………………………………………………………………………………………………………….. 3â€8
3.4.2
Benefit Question 1a ………………………………………………………………………………………………………………. 3â€17
3.4.3
Benefit Question 2 ………………………………………………………………………………………………………………… 3â€18
3.4.4
Benefit Question 2a ………………………………………………………………………………………………………………. 3â€22
3.4.5
Benefit Question 2b ………………………………………………………………………………………………………………. 3â€23
3.4.6
Benefit Question 2c ……………………………………………………………………………………………………………….. 3â€23
3.4.7
Benefit Question 2d ………………………………………………………………………………………………………………. 3â€24
3.5
Conclusion …………………………………………………………………………………………………………………………………… 3â€26
3.6
References ………………………………………………………………………………………………………………………………….. 3â€27
3.7
Appendices ………………………………………………………………………………………………………………………………….. 3â€31
3.7.1
Appendix 3â€1 SSC Literature Search Template ………………………………………………………………………….. 3â€32
3.7.2
Appendix 3â€2 SSC Performance Indicator Matrices ……………………………………………………………………. 3â€34
3.7.3
Appendix 3â€3 TAC Comments and Responses to Comments ……………………………………………………….. 3â€40
Application Questions ……………………………………………………………………………………………………………………………. 4â€1
4.1
Chapter Purpose and Contents ………………………………………………………………………………………………………… 4â€1
4.2
Overview of Work Completed …………………………………………………………………………………………………………. 4â€1
4.3
Approach to Answer Application Questions ………………………………………………………………………………………. 4â€1
4.4
Responses to Application Questions …………………………………………………………………………………………………. 4â€4
4.4.1
Application Question 1 …………………………………………………………………………………………………………….. 4â€4
4.4.2
Application Question 1a …………………………………………………………………………………………………………… 4â€6
4.4.3
Application Question 2. ………………………………………………………………………………………………………….. 4â€10
4.4.4
Application Question 2a. ………………………………………………………………………………………………………… 4â€13
4.4.5
Application Question 2b. ………………………………………………………………………………………………………… 4â€15
4.4.6
Application Question 3. ………………………………………………………………………………………………………….. 4â€17
4.5
Conclusion …………………………………………………………………………………………………………………………………… 4â€17
4.6
References ………………………………………………………………………………………………………………………………….. 4â€19
4.7
Appendices ………………………………………………………………………………………………………………………………….. 4â€21
4.7.1
Appendix 4â€1 Updated Matrices of SSC BMP Performance Indictors ……………………………………………. 4â€22
4.7.2
Appendix 4â€2 – TAC Comments and Responses to TAC Comments ……………………………………………… 4â€24
Conclusion ……………………………………………………………………………………………………………………………………………. 5â€1
5.1
Chapter Purpose and Contents ………………………………………………………………………………………………………… 5â€1
5.2
Overview of Work Completed …………………………………………………………………………………………………………. 5â€1
5.3
Overview of Study and Data Gaps ……………………………………………………………………………………………………. 5â€1
Structural Stormwater Controls | Science Review & Synthesis Project
5.3.1
Chapter 2 Define Requirements, Goals, and Vision ……………………………………………………………………… 5â€1
5.3.2
Chapter 3 Benefit Questions …………………………………………………………………………………………………….. 5â€2
5.3.3
Chapter 4 Application Questions ………………………………………………………………………………………………. 5â€3
5.4
Future Research Considerations ………………………………………………………………………………………………………. 5â€3
5.4.1
SSC Performance Limitations ……………………………………………………………………………………………………. 5â€4
5.4.2
Impact Factors ………………………………………………………………………………………………………………………… 5â€4
5.4.3
Performance Indicators ……………………………………………………………………………………………………………. 5â€4
5.5
Appendices ……………………………………………………………………………………………………………………………………. 5â€8
5.5.1
Appendix 5â€1 TAC Comments and Consultant Responses …………………………………………………………….. 5â€9
Structural Stormwater Controls | Science Review & Synthesis Project
vii
Acronyms
Structural Stormwater Controls | Science Review & Synthesis Project
viii
ACRONYMS
AKART
All Known, Available, and Reasonable Methods of Prevention, Control, and Treatment
BMP
Best Management Practice
DNR
Department of Natural Resources
Ecology
Washington State Department of Ecology
EIA
Effective Impervious Area
EPA
Environmental Protection Agency
ISBD
International Stormwater BMP Database
LID
Low Impact Development
MEP
Maximum Extent Practicable
MS4
Municipal Separate Stormwater Sewer System
NPDES
National Pollutant Discharge Elimination System
O&M
Operations and Maintenance
OCI
Osborn Consulting, Inc.
OHWM
Ordinary Highâ€Water Mark
PCHB
Pollution Control Hearings Board
ROW
Right of Way
SSC
Structural Stormwater Controls
SWMP
Stormwater Management Program
SWMMWW
Stormwater Management Manual for Western Washington
TAC
Technical Advisory Committy
TMDL
Total Maximum Daily Load
WAC
Washington Administrative Code
WEC
Washington Environmental Council
WSDOT
Washington State Department of Transportation
Structural Stormwater Controls
Executive Summary
Science Review & Synthesis Project
June 30, 2021
Page | 1
BACKGROUND AND PURPOSE
Executive Summary
In 2018, municipal stormwater (MS4) permittees in Western Washington requested a stakeholder group work on policy
and technical issues related to future Structural Stormwater Control (SSC) requirements. In response to this request, the
Washington State Department of Ecology (Ecology) in 2020 requested proposals to collect and summarize existing
scientific findings on SSCs and selected the City of Tacoma’s consultant team. The consultant team was…
Structural Stormwater Controls
Science Review and Synthesis Project
Final White Paper
Prepared for:
Washington State Department of Ecology
Prepared by:
Aimee S. Navickisâ€Brasch, PhD, PE
Osborn Consulting, Inc.
Maria Peraki, PhD, EIT
Osborn Consulting, Inc.
James Packman
Aspect Consulting
Paul Fendt, PE
Parametrix
Christian Nilsen, PE
Geosyntec Consultants
Taylor Hoffmanâ€Ballard, PE
Osborn Consulting, Inc.
Mark Maurer, PE, PLA
Osborn Consulting, Inc.
Structural Stormwater Controls | Science Review & Synthesis Project
iii
Table of Contents
Executive Summary …………………………………………………………………………………………………………………………………………….. 1
Introduction …………………………………………………………………………………………………………………………………………. 1â€1
1.1
Chapter Purpose and Contents ………………………………………………………………………………………………………… 1â€1
1.2
Overview of Work Completed …………………………………………………………………………………………………………. 1â€1
1.3
Project Purpose ……………………………………………………………………………………………………………………………… 1â€1
1.3.1
Project Background and Goals ………………………………………………………………………………………………….. 1â€1
1.3.2
Additional Goals ……………………………………………………………………………………………………………………… 1â€2
1.3.3
TAC Project Vision …………………………………………………………………………………………………………………… 1â€4
1.4
TAC and Consultant Team Role ………………………………………………………………………………………………………… 1â€5
1.5
White Paper Contents and Organization …………………………………………………………………………………………… 1â€6
1.5.1
Chapter 1. Introduction ……………………………………………………………………………………………………………. 1â€6
1.5.2
Chapter 2. Define Requirements ………………………………………………………………………………………………. 1â€6
1.5.3
Chapter 3. Benefit Questions ……………………………………………………………………………………………………. 1â€6
1.5.4
Chapter 4. Application Questions ……………………………………………………………………………………………… 1â€7
1.5.5
Chapter 5. Conclusion ……………………………………………………………………………………………………………… 1â€7
1.6
Appendices ……………………………………………………………………………………………………………………………………. 1â€8
1.6.1
Appendix 1â€1 TAC Comments and Consultant Responses …………………………………………………………….. 1â€9
Define Requirements, Goals, and Vision …………………………………………………………………………………………………… 2â€1
2.1
Chapter Purpose and Contents ………………………………………………………………………………………………………… 2â€1
2.2
Overview of Work Completed …………………………………………………………………………………………………………. 2â€1
2.3
Relevant Requirements …………………………………………………………………………………………………………………… 2â€1
2.4
Reasoning for Permit Language ……………………………………………………………………………………………………….. 2â€7
2.5
Overview of Jurisdictions SSC Programs ………………………………………………………………………………………….. 2â€10
2.6
References ………………………………………………………………………………………………………………………………….. 2â€17
2.7
Appendices ………………………………………………………………………………………………………………………………….. 2â€21
2.7.1
Appendix 2â€1 – Phase II Screening Questions and Responses ……………………………………………………… 2â€22
2.7.2
Appendix 2â€2 – Interview Questions ………………………………………………………………………………………… 2â€27
2.7.3
Appendix 2â€3 – Interview Responses: Phase I and Phase II …………………………………………………………. 2â€34
2.7.4
Appendix 2â€4 – TAC Comments and Responses to Comments …………………………………………………… 2â€130
Benefit Questions ………………………………………………………………………………………………………………………………….. 3â€1
3.1
Chapter Purpose and Contents ………………………………………………………………………………………………………… 3â€1
3.2
Overview of Work Completed …………………………………………………………………………………………………………. 3â€1
3.3
Literature Search ……………………………………………………………………………………………………………………………. 3â€1
3.3.1
Define Key Terms ……………………………………………………………………………………………………………………. 3â€1
3.3.2
Approach ……………………………………………………………………………………………………………………………….. 3â€3
Structural Stormwater Controls | Science Review & Synthesis Project
3.3.3
Summary of Literature Findings ………………………………………………………………………………………………… 3â€6
3.3.4
Summary of Research Gaps ……………………………………………………………………………………………………… 3â€6
3.4
Responses to Benefit Questions ………………………………………………………………………………………………………. 3â€7
3.4.1
Benefit Question 1 ………………………………………………………………………………………………………………….. 3â€8
3.4.2
Benefit Question 1a ………………………………………………………………………………………………………………. 3â€17
3.4.3
Benefit Question 2 ………………………………………………………………………………………………………………… 3â€18
3.4.4
Benefit Question 2a ………………………………………………………………………………………………………………. 3â€22
3.4.5
Benefit Question 2b ………………………………………………………………………………………………………………. 3â€23
3.4.6
Benefit Question 2c ……………………………………………………………………………………………………………….. 3â€23
3.4.7
Benefit Question 2d ………………………………………………………………………………………………………………. 3â€24
3.5
Conclusion …………………………………………………………………………………………………………………………………… 3â€26
3.6
References ………………………………………………………………………………………………………………………………….. 3â€27
3.7
Appendices ………………………………………………………………………………………………………………………………….. 3â€31
3.7.1
Appendix 3â€1 SSC Literature Search Template ………………………………………………………………………….. 3â€32
3.7.2
Appendix 3â€2 SSC Performance Indicator Matrices ……………………………………………………………………. 3â€34
3.7.3
Appendix 3â€3 TAC Comments and Responses to Comments ……………………………………………………….. 3â€40
Application Questions ……………………………………………………………………………………………………………………………. 4â€1
4.1
Chapter Purpose and Contents ………………………………………………………………………………………………………… 4â€1
4.2
Overview of Work Completed …………………………………………………………………………………………………………. 4â€1
4.3
Approach to Answer Application Questions ………………………………………………………………………………………. 4â€1
4.4
Responses to Application Questions …………………………………………………………………………………………………. 4â€4
4.4.1
Application Question 1 …………………………………………………………………………………………………………….. 4â€4
4.4.2
Application Question 1a …………………………………………………………………………………………………………… 4â€6
4.4.3
Application Question 2. ………………………………………………………………………………………………………….. 4â€10
4.4.4
Application Question 2a. ………………………………………………………………………………………………………… 4â€13
4.4.5
Application Question 2b. ………………………………………………………………………………………………………… 4â€15
4.4.6
Application Question 3. ………………………………………………………………………………………………………….. 4â€17
4.5
Conclusion …………………………………………………………………………………………………………………………………… 4â€17
4.6
References ………………………………………………………………………………………………………………………………….. 4â€19
4.7
Appendices ………………………………………………………………………………………………………………………………….. 4â€21
4.7.1
Appendix 4â€1 Updated Matrices of SSC BMP Performance Indictors ……………………………………………. 4â€22
4.7.2
Appendix 4â€2 – TAC Comments and Responses to TAC Comments ……………………………………………… 4â€24
Conclusion ……………………………………………………………………………………………………………………………………………. 5â€1
5.1
Chapter Purpose and Contents ………………………………………………………………………………………………………… 5â€1
5.2
Overview of Work Completed …………………………………………………………………………………………………………. 5â€1
5.3
Overview of Study and Data Gaps ……………………………………………………………………………………………………. 5â€1
Structural Stormwater Controls | Science Review & Synthesis Project
5.3.1
Chapter 2 Define Requirements, Goals, and Vision ……………………………………………………………………… 5â€1
5.3.2
Chapter 3 Benefit Questions …………………………………………………………………………………………………….. 5â€2
5.3.3
Chapter 4 Application Questions ………………………………………………………………………………………………. 5â€3
5.4
Future Research Considerations ………………………………………………………………………………………………………. 5â€3
5.4.1
SSC Performance Limitations ……………………………………………………………………………………………………. 5â€4
5.4.2
Impact Factors ………………………………………………………………………………………………………………………… 5â€4
5.4.3
Performance Indicators ……………………………………………………………………………………………………………. 5â€4
5.5
Appendices ……………………………………………………………………………………………………………………………………. 5â€8
5.5.1
Appendix 5â€1 TAC Comments and Consultant Responses …………………………………………………………….. 5â€9
Structural Stormwater Controls | Science Review & Synthesis Project
vii
Acronyms
Structural Stormwater Controls | Science Review & Synthesis Project
viii
ACRONYMS
AKART
All Known, Available, and Reasonable Methods of Prevention, Control, and Treatment
BMP
Best Management Practice
DNR
Department of Natural Resources
Ecology
Washington State Department of Ecology
EIA
Effective Impervious Area
EPA
Environmental Protection Agency
ISBD
International Stormwater BMP Database
LID
Low Impact Development
MEP
Maximum Extent Practicable
MS4
Municipal Separate Stormwater Sewer System
NPDES
National Pollutant Discharge Elimination System
O&M
Operations and Maintenance
OCI
Osborn Consulting, Inc.
OHWM
Ordinary Highâ€Water Mark
PCHB
Pollution Control Hearings Board
ROW
Right of Way
SSC
Structural Stormwater Controls
SWMP
Stormwater Management Program
SWMMWW
Stormwater Management Manual for Western Washington
TAC
Technical Advisory Committy
TMDL
Total Maximum Daily Load
WAC
Washington Administrative Code
WEC
Washington Environmental Council
WSDOT
Washington State Department of Transportation
Structural Stormwater Controls
Executive Summary
Science Review & Synthesis Project
June 30, 2021
Page | 1
BACKGROUND AND PURPOSE
Executive Summary
In 2018, municipal stormwater (MS4) permittees in Western Washington requested a stakeholder group work on policy
and technical issues related to future Structural Stormwater Control (SSC) requirements. In response to this request, the
Washington State Department of Ecology (Ecology) in 2020 requested proposals to collect and summarize existing
scientific findings on SSCs and selected the City of Tacoma’s consultant team. The consultant team was…
