Eastern Washington
Stormwater Effectiveness Studies
Final Technical Evaluation Report
Non-Vegetated Filtration Swale Stormwater
Effectiveness Study
Study Classification:
 Structural BMP
ï‚£ Operational BMP
ï‚£ Education & Outreach
Study Objective(s):
 Evaluate Effectiveness
ï‚£ Compare Effectiveness
 Develop Modified BMP
ï‚£ Develop New BMP
Prepared For:
City of West Richland
Public Works Department
3100 Belmont Blvd. Suite 102
West Richland, WA 99353
Prepared By:
Evergreen StormH2O, LLC
PO Box 18912
Spokane, Washington 99228
April 2023
Final TER
Non-Vegetated Filtration Swale Stormwater Effectiveness Study
April 2023
Page | i
Publication Information
The QAPP and TER will be available to the public on the City of West Richland website
(https://www.westrichland.org/189/Stormwater).
Authors and Contact Information
Taylor Hoffman-Ballard, PE
Evergreen StormH2O, LLC
Project Manager
PO Box 18912
Spokane, WA 99228
[email protected]
952-836-7863
Aimee Navickis-Brasch, PhD, PE
Evergreen StormH2O, LLC
Principal and President
PO Box 18912
Spokane, WA 99228
[email protected]
509-995-0557
Patrick Volsky
Engineer-In-Training
Evergreen StormH2O, LLC
PO Box 18912
Spokane, WA 99228
[email protected]
206-948-7415
Mark Maurer, PE, PLA
Evergreen StormH2O, LLC
Senior Stormwater Engineer
PO Box 18912
Spokane, WA 99228
[email protected]
360-790-6421
Final TER
Non-Vegetated Filtration Swale Stormwater Effectiveness Study
April 2023
Page | ii
Acknowledgements
This project was funded by a Washington State Department of Ecology (Ecology) Grant of Regional of
Statewide Significance (GROSS). The technical advisory committee (TAC) along with City of West
Richland staff played an integral role in this project. The City of West Richland served as the lead entity
with the following jurisdictions serving as participating entities: City of Richland, City of Kennewick, City
of Pasco, City of Walla Walla, and Walla Walla County. The TAC consisted of staff members from the
lead and participating entities along with Ecology. TAC participation included providing input on the
project deliverables as well as assisting with data collection during field testing. In addition,
maintenance staff from the City of West Richland, including Don Klages, Chris Hogan, Jeremy Gwinn,
Derek Vahanian, and Jared Rheinschmidt, constructed the test site and were an integral part of running
the simulated events and data collection. Most of the field testing occurred during the record-setting
heat wave in the summer of 2022 and in poor air quality due to forest fires in the Pacific Northwest.
Many of the photos in this document were taken by TAC members, who were also helping with data
collection, and credit has been given to them in figure titles (the photo on the cover page of this
document was taken by staff from the City of West Richland).
Document History
The study was conducted following Ecology’s approval of the QAPP, which can be accessed at this site:
https://www.westrichland.org/189/Stormwater. The data collection started in August 2022, and the last
data was collected in January 2023. The draft Technical Evaluation Report (TER) was presented and
submitted to the TAC in March 2023 for review and comment. Appendix A of the TER contains a
summary of the TAC’s comments along with a summary of the consultants’ responses to the comments,
including how they were addressed in the document. The final TER was completed in April 2023.
Final TER
Non-Vegetated Filtration Swale Stormwater Effectiveness Study
April 2023
Page | iii
Signature Page
Approved by:
Date
Drew Woodruff, Lead Entity, City of West Richland
Date
Martin Nelson, Contributing Entity, City of Kennewick
Date
Brian Pope, Contributing Entity, City of Richland
Date
Michael Henao, Contributing Entity, City of Pasco
Date
Steve Kelley, Contributing Entity, City of Walla Walla
Date
Seth Walker, Contributing Entity, Walla Walla County
Date
Mark Melton, Ecology Water Quality Program Reviewing Engineer
Date
Andrea Jedel, Ecology Water Quality Program Project/Permit Manager
Date
Aimee Navickis-Brasch, Primary Author, Evergreen StormH2O, LLC
Signatures are not available on the Internet version.
05/09/2023
Final TER
Non-Vegetated Filtration Swale Stormwater Effectiveness Study
April 2023
Page | iii
Signature Page
Approved by:
Date
Drew Woodruff, Lead Entity, City of West Richland
Date
Martin Nelson, Contributing Entity, City of Kennewick
Date
Brian Pope, Contributing Entity, City of Richland
Date
Michael Henao, Contributing Entity, City of Pasco
Date
Steve Kelley, Contributing Entity, City of Walla Walla
Date
Seth Walker, Contributing Entity, Walla Walla County
Date
Mark Melton, Ecology Water Quality Program Reviewing Engineer
Date
Andrea Jedel, Ecology Water Quality Program Project/Permit Manager
Date
Aimee Navickis-Brasch, Primary Author, Evergreen StormH2O, LLC
Signatures are not available on the Internet version.
Steven Kelley
Digitally signed by Steven Kelley
DN: C=US, [email protected], O=City of Walla Walla, CN=Steven Kelley
Date: 2023.05.08 15:50:00-07'00'
Final TER
Non-Vegetated Filtration Swale Stormwater Effectiveness Study
April 2023
Page | iii
Signature Page
Approved by:
Date
Drew Woodruff, Lead Entity, City of West Richland
Date
Martin Nelson, Contributing Entity, City of Kennewick
Date
Brian Pope, Contributing Entity, City of Richland
Date
Michael Henao, Contributing Entity, City of Pasco
Date
Steve Kelley, Contributing Entity, City of Walla Walla
Date
Seth Walker, Contributing Entity, Walla Walla County
Date
Mark Melton, Ecology Water Quality Program Reviewing Engineer
Date
Andrea Jedel, Ecology Water Quality Program Project/Permit Manager
Date
Aimee Navickis-Brasch, Primary Author, Evergreen StormH2O, LLC
Signatures are not available on the Internet version.
Final TER
Non-Vegetated Filtration Swale Stormwater Effectiveness Study
April 2023
Page | iii
Signature Page
Approved by:
Date
Drew Woodruff, Lead Entity, City of West Richland
Date
Martin Nelson, Contributing Entity, City of Kennewick
Date
Brian Pope, Contributing Entity, City of Richland
Date
Michael Henao, Contributing Entity, City of Pasco
Date
Steve Kelley, Contributing Entity, City of Walla Walla
Date
Seth Walker, Contributing Entity, Walla Walla County
Date
Mark Melton, Ecology Water Quality Program Reviewing Engineer
Date
Andrea Jedel, Ecology Water Quality Program Project/Permit Manager
Date
Aimee Navickis-Brasch, Primary Author, Evergreen StormH2O, LLC
Signatures are not available on the Internet version.
5/22/23
Final TER
Non-Vegetated Filtration Swale Stormwater Effectiveness Study
April 2023
Page | iv
Distribution List
The distribution list includes each party who will receive a copy of the TER.
Name, Title
Organization
Contact Information:
Address, Telephone, Email
Drew Woodruff1
City Engineer
City of West Richland
[email protected]
509-967-5434
Martin Nelson1
Public Works Development
Review Supervisor
City of Kennewick
[email protected]
509-585-4306
Brian Pope1
Civil Engineer
City of Richland
[email protected]
509-942-7508
Michael Henao1
Environmental Compliance
Coordinator
City of Pasco
[email protected]
509-545-3454
Steve Kelley1
Stormwater Coordinator
City of Walla Walla
[email protected]
509-527-4669
Seth Walker1
Chief of Engineering &
Construction
Walla Walla County
[email protected]
509-524-2710
Joy Bader1
Technician IV
Walla Walla County
[email protected]
509-524-2733
Chuck Geissel1
Technician III
Walla Walla County
[email protected]
509-524-2729
Andrea Jedel1
Water Quality PM
Washington State
Department of Ecology
[email protected]
509-961-0625
Doug Howie1, 2
Senior Stormwater Engineer
Washington State
Department of Ecology
[email protected]
360-870-0983
Jamie Brunner1
Lake Management Plan
Supervisor
Idaho Department of
Environmental Quality
[email protected]
208-666-4623
Kristen Lowell1
Senior Water Quality Analyst
Idaho Department of
Environmental Quality
[email protected]
208-769-1422
Aimee Navickis-Brasch
Principal and President
Evergreen StormH2O, LLC
[email protected]
509-995-0557
Taylor Hoffman-Ballard
Project Manager
Evergreen StormH2O, LLC
[email protected]
509-867-3650
Patrick Volsky
Engineer-In-Training
Evergreen StormH2O, LLC
[email protected]
206-948-7415
Mark Maurer
Senior Stormwater Engineer
Evergreen StormH2O, LLC
[email protected]
(509) 867-3654
1 The organizations listed were part of the Technical Advisory Committee (TAC). The goal of the TAC was
to provide insight, suggestions, and professional opinions to the research team throughout the study.
2 TAC Member was not involved in the review of the TER.
Final TER
Non-Vegetated Filtration Swale Stormwater Effectiveness Study
April 2023
Page | v
Table of Contents
PUBLICATION INFORMATION ………………………………………………………………………………………………. I
AUTHORS AND CONTACT INFORMATION ……………………………………………………………………………….. I
ACKNOWLEDGEMENTS ……………………………………………………………………………………………………… II
DOCUMENT HISTORY ………………………………………………………………………………………………………… II
SIGNATURE PAGE …………………………………………………………………………………………………………….. III
DISTRIBUTION LIST …………………………………………………………………………………………………………… IV
TABLE OF CONTENTS …………………………………………………………………………………………………………. V
EXECUTIVE SUMMARY ………………………………………………………………………………………………………..1
OBJECTIVES AND RESULTS …………………………………………………………………………………………………………………………….. 1
RECOMMENDATIONS ………………………………………………………………………………………………………………………………….. 2
INTRODUCTION ………………………………………………………………………………………………………4
1.1
INTRODUCTION TO THE STRUCTURAL BMP …………………………………………………………………………………………………. 4
1.2
PROBLEM DESCRIPTION ……………………………………………………………………………………………………………………….. 5
1.3
PROJECT GOALS AND OBJECTIVES ……………………………………………………………………………………………………………. 6
1.4
PROJECT OVERVIEW ……………………………………………………………………………………………………………………………. 7
1.5
STUDY LOCATION ………………………………………………………………………………………………………………………………. 8
SAMPLING PROCEDURES ………………………………………………………………………………………… 10
2.1
TYPES OF DATA COLLECTED …………………………………………………………………………………………………………………. 10
2.2
SAMPLE COLLECTION PROCESS ……………………………………………………………………………………………………………… 11
2.2.1
SOP Overview ……………………………………………………………………………………………………………………… 11
2.2.2
Influent (Synthetic Stormwater) Distribution System and Sample Equipment Overview ……………….. 11
2.2.3
Audit Overview ……………………………………………………………………………………………………………………. 14
DATA QUALITY ASSESSMENT …………………………………………………………………………………… 15
3.1
DATA VERIFICATION ………………………………………………………………………………………………………………………….. 15
3.2
DATA USABILITY ASSESSMENT ……………………………………………………………………………………………………………… 16
DATA SUMMARIES AND ANALYSIS …………………………………………………………………………… 18
4.1
INTRODUCTION TO WATER QUALITY RESULTS ……………………………………………………………………………………………. 18
4.2
RECOMMENDATIONS FOR FINAL SWALE ALTERNATIVE ………………………………………………………………………………….. 20
4.3
EVALUATION OF FINAL SWALE ALTERNATIVE ……………………………………………………………………………………………… 20
4.4
STATISTICAL COMPARISON OF POLLUTANT CONCENTRATIONS …………………………………………………………………………. 34
4.5
WATER QUALITY TREATMENT PERFORMANCE ……………………………………………………………………………………………. 36
CONSTRUCTION, DESIGN, AND OPERATION AND MAINTENANCE CONSIDERATIONS ………….. 38
5.1
CONSTRUCTION CONSIDERATIONS …………………………………………………………………………………………………………. 38
5.2
DESIGN RECOMMENDATIONS ………………………………………………………………………………………………………………. 38
5.2.1
Length of Swale and Hydraulic Residence Time ……………………………………………………………………….. 38
5.2.2
Manning’s n Verification ………………………………………………………………………………………………………. 41
5.3
OPERATION AND MAINTENANCE CONSIDERATIONS ……………………………………………………………………………………… 42
FUTURE ACTION RECOMMENDATIONS ……………………………………………………………………… 43
CONCLUSIONS ……………………………………………………………………………………………………… 45
Final TER
Non-Vegetated Filtration Swale Stormwater Effectiveness Study
April 2023
Page | vi
7.1
RECOMMENDATIONS ………………………………………………………………………………………………………………………… 46
REFERENCES ………………………………………………………………………………………………………… 47
APPENDICES…