Eastern Washington
Stormwater Effectiveness Studies
Quality Assurance Project Plan
Bioretention Soil Media Thickness Study
Study Classification: Structural BMP
Study Objective(s):
 Evaluate Effectiveness
 Compare Effectiveness
 Develop Modified BMP
June 23, 2020
Prepared For:
Spokane County
Public Works Department
1116 W. Broadway Avenue
Spokane, Washington 99260
(509)477-3600
Prepared By:
Osborn Consulting, Inc.
101 S Stevens St.
Spokane, Washington 99201
(509)867-3654
FINAL QAPP
BIORETENTION SOIL MEDIA THICKNESS STUDY
June 23, 2020
Page | ii
Proposal and QAPP Publication Information
The Detailed Study Design Proposal (Proposal) and Quality Assurance Project Plan (QAPP) will
stored
and
accessible
the
public
the
Spokane
County’s
website:
https://www.spokanecounty.org/918/Stormwater-Utility.
For
questions
regarding
either
document, please contact Matt Zarecor by email [email protected] or phone (509)
477-7255.
Proposal Authors and Contact Information
Aimee Navickis-Brasch, P.E., Ph.D. Candidate
Zack Holt
Senior Stormwater Engineer
Environmental Services Director
HDR, Inc.
D&H Technology Solutions, LLC
1401 E. Trent Ave., Suite 101
15206 131st Ave. CT KPN
Spokane, WA 99202
Gig Harbor, Washington 9329
(509) 343-8515
[email protected]
(360) 509-0996
QAPP Authors and Contact Information
Aimee Navickis-Brasch, P.E., Ph.D.
Chad Wiseman
Senior Project Manager & Stormwater Engineer
Water Quality Specialist
Osborn Consulting, Inc.
HDR, Inc.
101 S Stevens St.
905 Plum Street NE Suite 200
Spokane, WA 99201
Olympia, WA 98501
[email protected]
[email protected]
(509) 867-3654 Ext. 301
(360) 570-4427
Taylor Hoffman-Ballard, E.I.T.
Stormwater Engineer
Osborn Consulting, Inc.
101 S Stevens St.
Spokane, WA 99201
[email protected]
(509) 867-3654 Ext. 302
FINAL QAPP
BIORETENTION SOIL MEDIA THICKNESS STUDY
June 23, 2020
Page | iii
Document History
This document was developed following the Eastern Washington (EWA) Detailed Study Design
Proposal and Quality Assurance Project Plan Template for Structural Best Management Practices
(BMPs). A copy of the template is located on the City of Spokane Valley’s website at the following
web link: http://www.spokanevalley.org/content/6836/6896/6914/8301/10121/default.aspx
A Detailed Study Design Proposal (Proposal) was submitted to Ecology on June 30, 2017 and
Ecology approved the Proposal via email to Spokane County on November 8th, 2017. Appendix A
contains a copy of the email along with Ecology’s comments on the Proposal. Appendix B contains
a summary of HDR’s responses to Ecology’s comments including how the comments were
incorporated into the Quality Assurance Project Plan (QAPP).
The study goal described in this QAPP has changed since the Proposal was approved by Ecology.
Specifically, the Proposal goal was to evaluate the treatment performance of a bioretention cell
that contains vegetation compared to a bioretention cell without vegetation. Both cells would have
contained either the bioretention soil media (BSM) that is under development in western
Washington (WWA) or the 60:40 BSM that is currently approved by Ecology. Whereas the goal
of the study defined in this QAPP is to evaluate the treatment performance of a bioretention cell
that contains 12-inches of the 60:40 BSM compared to a cell that contains 18-inches of the same
BSM. Both study ideas were identified by the Eastern Washington Stormwater Permittees during
earlier phases of the Effectiveness Studies and both studies were ranked as one of the top 14 top
studies (with the same score) on the list submitted to Ecology on June 30, 2016. (Reference the
weblink at the top of this page for more details about the history of the EWA Effectiveness
Studies).
The study QAPP was submitted to Ecology on May 8, 2018 for their review and comment.
Ecology provided their comments on the QAPP to Spokane County on August 23, 2018. Appendix
C contain a copy of Ecology’s QAPP approval letter and a summary of Ecology’s comments along
with HDR’s responses to the comments including how the comments were incorporated into the
final QAPP document. The final QAPP was submitted to Ecology on September 28, 2018.
FINAL QAPP
BIORETENTION SOIL MEDIA THICKNESS STUDY
May 8, 2018
Page | iv
Signature Page
Approved by:
Date 6/24/2020
Jake SaxonEthan Murnin, Lead Entity, Spokane County
Date 6/23/2020
Aimee Navickis-Brasch, Primary Author, HDR, Inc.
Date
Kathy Sattler, Anatek Laboratories Laboratory Project Manager
Date
Stephen BurchettTerri Ballard, Ecology, Budinger & Associates, Laboratory Manager
Date
Medhanie Tecle, Materials Testing & Consulting, Inc., Engineering Manager
Date
Adriane Borgias, Ecology, Water Quality Project Manager
Date
Amanda Mars, Ecology, Ecology Water Quality Program – ERO
Date
Doug Howie, Ecology, Reviewer Structural and Operational BMP Studies
Date
Brandi Lubliner, Ecology, Reviewer Monitoring System Designs
06/24/2020
6/23/2020
6/22/2020
FINAL QAPP
BIORETENTION SOIL MEDIA THICKNESS STUDY
June 23, 2020
Page | v
Distribution List
This section includes the distribution list for each party who will receive an Ecology approved
copy of the QAPP.
Name, Title
Organization
Contact Information:
Email, Telephone
Matt Zarecor
Assistant County Engineer
Spokane County
[email protected]
509-477-7255
Bill Gale
Stormwater Utility Manager
Spokane County
[email protected]
509-477-7261
Ethan Murnin
Project Manager
Spokane County
[email protected]
509-477-7420
David Haws,
Water Resource Supervisor
Yakima County
[email protected]
509.574.2300
Chad Philips,
Stormwater Engineer
City of Spokane Valley
[email protected]
509.720.5018
Seth Walker
Walla Walla County
Participating Entity
TAG Member6
509-524-2715
[email protected]
Shilo Sprouse
Stormwater Services Program
Manager
City of Pullman
[email protected]
509.432.9052
Randy Meloy,
Surface Water Engineer
City of Yakima
509.576.6781
[email protected]
Bill Aukett, Stormwater
Program Manager
City of Moses Lake
509.764.3792
[email protected]
Brian Olle,
City Engineer
City of Pasco
509.545.3445
[email protected]
Karen Dinicola,
Phase 2-3a Gross Grant Ecology
Project Manager
Department of Ecology
[email protected]
360.407.6550
Doug Howie,
Reviewer Structural &
Operational BMPs
Department of Ecology
[email protected]
360.407.6444
Brandi Lubliner,
Reviewer Monitoring System
Designs
Department of Ecology
[email protected]
360.407.7140
Amanda Mars
WQ Program – ERO
Department of Ecology
[email protected]
509-329-3554
Aimee Navickis-Brasch,
Senior Project Manager &
Stormwater Engineer
Osborn Consulting, Inc.
[email protected]
509.867.3654
Taylor Hoffman,
Stormwater Engineer
Osborn Consulting, Inc.
[email protected]
509.867.3654
Kathy Sattler, Laboratory
Project Manager
Anatek Laboratories
[email protected]
509-838-3999
Medhanie Tecle,
Engineering Manager
Materials Testing &
Consulting, Inc.
[email protected]
360-534-9777
FINAL QAPP
BIORETENTION SOIL MEDIA THICKNESS STUDY
June 23, 2020
Page | vi
1.0
Table of Contents
PROPOSAL AUTHORS AND CONTACT INFORMATION ……………………………………………………………….II
QAPP AUTHORS AND CONTACT INFORMATION………………………………………………………………………….II
DOCUMENT HISTORY ……………………………………………………………………………………………………………………… III
SIGNATURE PAGE …………………………………………………………………………………………………………………………….. IV
DISTRIBUTION LIST ……………………………………………………………………………………………………………………………V
1.0
TABLE OF CONTENTS ………………………………………………………………………………………………………………. VI
2.0
EXECUTIVE SUMMARY ………………………………………………………………………………………………………………. 2
3.0
INTRODUCTION AND BACKGROUND ……………………………………………………………………………………. 3
3.1
INTRODUCTION TO THE STRUCTURAL BMP …………………………………………………………………………………….. 3
3.2
BACKGROUND AND PROBLEM DESCRIPTION ……………………………………………………………………………………. 4
3.3
RESULTS OF PRIOR STUDIES ……………………………………………………………………………………………………………. 5
3.4
REGULATORY REQUIREMENTS ……………………………………………………………………………………………………….. 6
4.0
PROJECT OVERVIEW …………………………………………………………………………………………………………………… 7
4.1
STUDY GOAL ………………………………………………………………………………………………………………………………… 7
4.2
STUDY DESCRIPTION AND OBJECTIVES: …………………………………………………………………………………………… 7
4.3
STUDY LOCATION …………………………………………………………………………………………………………………………. 8
4.4
DATA NEEDED TO MEET OBJECTIVES ……………………………………………………………………………………………… 9
4.5
TASKS REQUIRED TO CONDUCT STUDY …………………………………………………………………………………………. 10
4.6
POTENTIAL CONSTRAINTS ……………………………………………………………………………………………………………. 11
5.0
ORGANIZATION AND SCHEDULE………………………………………………………………………………………….. 12
5.1
KEY PROJECT TEAM MEMBERS: ROLES AND RESPONSIBILITIES …………………………………………………………. 12
5.2
PROJECT SCHEDULE …………………………………………………………………………………………………………………….. 14
5.3
BUDGET AND FUNDING SOURCES …………………………………………………………………………………………………. 15
6.0
QUALITY OBJECTIVES ………………………………………………………………………………………………………………. 16
6.1
PRECISION ………………………………………………………………………………………………………………………………….. 21
6.2
BIAS …………………………………………………………………………………………………………………………………………… 21
6.3
REPRESENTATIVENESS …………………………………………………………………………………………………………………. 22
7.0
EXPERIMENTAL DESIGN ………………………………………………………………………………………………………….. 24
7.1
STUDY DESIGN OVERVIEW …………………………………………………………………………………………………………… 24
7.2
TEST-SITE(S) SELECTION PROCESS …………………………………………………………………………………………………. 28
7.3
THE STRUCTURAL BMP SYSTEM SIZING ………………………………………………………………………………………… 28
7.4
TYPE OF DATA BEING COLLECTED ………………………………………………………………………………………………… 29
7.5
PRECIPITATION MONITORING ………………………………………………………………………………………………………. 30
7.5.1
Storm Event Prediction ……………………………………………………………………………………………………….. 30
7.5.2
Rainfall Measurements ………………………………………………………………………………………………………… 31
7.6
WATER QUALITY SAMPLING ……………………………………………………………………………………………………. 32
7.6.1
Grab Sampling ……………………………………………………………………………………………………………………. 32
7.6.2
Composite Sampling ……………………………………………………………………………………………………………. 32
7.7
SATURATED HYDRAULIC CONDUCTIVITY TESTING…………………………………………………………………………. 32
7.8
INFLUENT SEDIMENT PARTICLE SIZE DISTRIBUTION ……………………………………………………………………….. 32
7.9
BSM MATERIAL TESTING …………………………………………………………………………………………………………….. 33
8.0
SAMPLING PROCEDURES ………………………………………………………………………………………………………… 34
FINAL QAPP
BIORETENTION SOIL MEDIA THICKNESS STUDY
June 23, 2020
Page | vii
8.1
STANDARD OPERATING PROCEDURES …………………………………………………………………………………………… 34
8.1.1
Storm Selection and Tracking ………………………………………………………………………………………………. 34
8.1.2
Storm Monitoring Equipment Maintenance …………………………………………………………………………… 35
8.1.3
Preparing Stormwater Monitoring Equipment for Storm Sampling ………………………………………….. 38
8.1.4
Stormwater Grab Sampling – Not Used for This QAPP ………………………………………………………….. 42
8.1.5
Stormwater Sample Collection and Processing ……………………………………………………………………….. 42
8.1.6
Monitoring Equipment Data Download ………………………………………………………………………………… 44
8.1.7
Accumulated Sediment PSD Sample Collection– Not Used for This QAPP ……………………………….. 45
8.1.8
Falling Head Test ……………………………………………………………………………………………………………….. 46
8.2
CONTAINERS, PRESERVATION METHODS, HOLDING TIMES …………………………………………………………….. 46
8.3
EQUIPMENT DECONTAMINATION …………………………………………………………………………………………………. 48
8.4
SAMPLE IDENTIFICATION…

Eastern Washington
Stormwater Effectiveness Studies
Quality Assurance Project Plan
Sand Filter Sidewalk Vault BMP
Study Classification: Structural BMP
Study Objective(s):  Evaluate Effectiveness
 Develop New BMP
November 1st, 2018
Prepared For:
Spokane County
Public Works Department
1116 W. Broadway Avenue
Spokane, Washington 99260
(509)477-3600
Prepared By:
HDR, Inc.
1401 E. Trent Ave., Suite 101
Spokane, Washington 99202
(509)343-8500
FINAL QAPP
SAND FILTER SIDEWALK VAULT BMP
November 1, 2018
Page | ii
Proposal and QAPP Publication Information
This Detailed Study Design Proposal (Proposal) and Quality Assurance Project Plan (QAPP) will
be stored and accessible to the public on the Spokane County’s website:
https://www.spokanecounty.org/918/Stormwater-Utility. For questions regarding the Proposal,
please contact Matt Zarecor by email [email protected] or phone (509) 477-7255.
Proposal Authors and Contact Information
Aimee Navickis-Brasch, P.E., Ph.D. Candidate
Zack Holt
Senior Stormwater Engineer
Environmental Services Director
HDR, Inc.
D&H Technology Solutions, LLC
1401 E. Trent Ave., Suite 101
15206 131st Ave. CT KPN
Spokane, WA 99202
Gig Harbor, Washington 9329
[email protected]
[email protected]
(509) 343-8515
(360) 509-0996
QAPP Authors and Contact Information
Aimee Navickis-Brasch, P.E., Ph.D.
Chad Wiseman
Senior Stormwater Engineer
Water Quality Specialist
HDR, Inc.
1401 E. Trent Ave., Suite 101
905 Plum Street NE Suite 200
Spokane, WA 99202
Olympia, WA 98501
[email protected]
[email protected]
(509) 343-8515
(360) 570-4427
Taylor Hoffman-Ballard, E.I.T.
Stormwater Research Engineer
HDR, Inc.
1401 E. Trent Ave., Suite 101
Spokane, WA 99202
[email protected]
(509) 343-8477
Proposal and QAPP Peer Review and Contact Information
Donald D. Carpenter, PhD, PE, LEED AP
Drummond Carpenter, PLLC
Vice President & Principal
9085 Montezuma
Kalamazoo, MI 49009
[email protected]
(248) 763-4099
FINAL QAPP
SAND FILTER SIDEWALK VAULT BMP
November 1, 2018
Page | iii
Document History
This document was developed following the Eastern Washington (EWA) Detailed Study Design
Proposal and Quality Assurance Project Plan Template for Structural Best Management Practices
(BMPs). A copy of the template is located on the City of Spokane Valley’s website at the following
web link: http://www.spokanevalley.org/content/6836/6896/6914/8301/10121/default.aspx
The Detailed Study Design Proposal (Proposal) was submitted to Ecology on June 30, 2017.
Ecology approved the Proposal via email to Spokane County on November 8th, 2017. Appendix A
contains a copy of the email along with Ecology’s comments on the Proposal. Appendix B contains
a summary of HDR’s responses to Ecology’s comments including how the comments were
incorporated into the Quality Assurance Project Plan (QAPP).
The draft QAPP was reviewed by members of the Technical Advisory Group (TAG) in April 2018.
Appendix C contains a summary of the TAG’s comments along with a summary of HDR’s
response to these comments including how the comments were addressed in this document. The
QAPP was submitted to Ecology by the May 8, 2018 deadline for their review and comment.
Comments from Ecology on the QAPP were provided via email on August 30th. Appendix D
contains a copy of Ecology’s QAPP review comments along with HDR’s responses to the
comments including how the comments were incorporated into the final QAPP document.
November 1, 2018
FINAL QAPP
SAND FILTER SIDEWALK VAULT BMP
November 1, 2018
Page | v
Distribution List
Name, Title
Organization
Contact Information:
E-mail, Telephone
Jake Saxon,
Project Manager
Spokane County
[email protected]
509-477-7245
Matt Zarecor
Assistant County Engineer
Spokane County
[email protected]
509-477-7255
Bill Gale
Stormwater Utility Manager
Spokane County
[email protected]
509-477-7261
Ethan Murnin
Stormwater Engineer
Spokane County
[email protected]
509-477-7261
Bill Aukett
Stormwater Program
Manager
City of Moses Lake
[email protected]
509-764-3792
Rob Buchert,
Stormwater Services
Program Manager
City of Pullman
[email protected]
509-338-3314
Nigel Pickering
Research Associate
Professor
Washington State
University
[email protected]
509-335-8624
Danielle Mullins
Stormwater Lead
City of West Richland
[email protected]
509-967-5434
Doug Howie,
Reviewer Structural and
Operational BMP Studies
Department of Ecology
[email protected]
360-407-6444
Karen Dinicola,
Phase 2-3a Gross Grant
Ecology Project Manager
Department of Ecology
[email protected]
360.407.6550
Brandi Lubliner,
Reviewer Monitoring
System Designs
Department of Ecology
[email protected]
360.407.7140
Adriane Borgias,
WQ Project Manager
Department of Ecology
[email protected]
509-329-3515
Aimee Navickis-Brasch,
Senior Stormwater Engineer
HDR, Inc.
[email protected]
509-343-8515
Taylor Hoffman-Ballard,
SW Research Engineer
HDR, Inc.
[email protected]
509-343-8477
Chad Wiseman,
Water Quality Specialist
HDR, Inc.
[email protected]
360-570-4427
Ed Griffenberg,
Senior Operations Specialist
HDR, Inc.
[email protected]
425-245-9131
Donald Carpenter
QAPP Peer Review
Drummond Carpenter,
PLLC
[email protected]
248-763-4099
Kathy Sattler, Laboratory
Project Manager
Anatek Laboratories
[email protected]
509-838-3999
Stephen Burchett
Environmental Engineer
Principal
Budinger & Associates
[email protected]
509-535-8841
FINAL QAPP
SAND FILTER SIDEWALK VAULT BMP
November 1, 2018
Page | vi
1.0
Table of Contents
DOCUMENT HISTORY ……………………………………………………………………………………………………………………… III
SIGNATURE PAGE …………………………………………………………………………………………………………………………….. IV
DISTRIBUTION LIST ……………………………………………………………………………………………………………………………V
1.0
TABLE OF CONTENTS ………………………………………………………………………………………………………………. VI
2.0
EXECUTIVE SUMMARY ………………………………………………………………………………………………………………. 1
3.0
INTRODUCTION AND BACKGROUND ……………………………………………………………………………………. 2
3.1
INTRODUCTION TO THE STRUCTURAL BMP…………………………………………………………………………………. 2
3.2
PROBLEM DESCRIPTION …………………………………………………………………………………………………………….. 3
3.3
RESULTS OF COLUMN TESTING SAND MEDIA ………………………………………………………………………………. 4
3.4
REGULATORY REQUIREMENTS ………………………………………………………………………………………………….. 12
4.0
PROJECT OVERVIEW …………………………………………………………………………………………………………………. 14
4.1
STUDY GOAL ………………………………………………………………………………………………………………………….. 14
4.2
STUDY DESCRIPTION AND OBJECTIVES ……………………………………………………………………………………… 14
4.3
STUDY LOCATION …………………………………………………………………………………………………………………… 15
4.4
DATA NEEDED TO MEET OBJECTIVES………………………………………………………………………………………… 16
4.5
TASKS REQUIRED TO CONDUCT STUDY …………………………………………………………………………………….. 18
4.6
POTENTIAL CONSTRAINTS ……………………………………………………………………………………………………….. 19
5.0
ORGANIZATION AND SCHEDULE………………………………………………………………………………………….. 20
5.1
KEY PROJECT TEAM MEMBERS: ROLES AND RESPONSIBILITIES …………………………………………………….. 20
5.2
PROJECT SCHEDULE ………………………………………………………………………………………………………………… 22
5.3
BUDGET AND FUNDING SOURCES …………………………………………………………………………………………….. 23
6.0
QUALITY OBJECTIVES ………………………………………………………………………………………………………………. 24
6.1
PRECISION ……………………………………………………………………………………………………………………………… 29
6.2
BIAS ………………………………………………………………………………………………………………………………………. 29
6.3
REPRESENTATIVENESS……………………………………………………………………………………………………………… 30
7.0
EXPERIMENTAL DESIGN ………………………………………………………………………………………………………….. 32
7.1
STUDY DESIGN OVERVIEW ………………………………………………………………………………………………………. 32
7.2
TEST-SITE(S) SELECTION PROCESS …………………………………………………………………………………………….. 36
7.3
THE STRUCTURAL BMP SYSTEM SIZING ……………………………………………………………………………………. 36
7.4
TYPE OF DATA BEING COLLECTED ……………………………………………………………………………………………. 39
7.5
PRECIPITATION MONITORING ………………………………………………………………………………………………….. 40
7.6
WATER QUALITY SAMPLING ……………………………………………………………………………………………………. 42
7.7
INFILTRATION TESTING ……………………………………………………………………………………………………………. 43
7.8
SEDIMENT SAMPLING ……………………………………………………………………………………………………………… 43
7.9
SAND FILTER MEDIA MATERIAL TESTING …………………………………………………………………………………. 43
8.0
SAMPLING PROCEDURES ………………………………………………………………………………………………………… 45
8.1
PROCEDURES FOR COLLECTING FIELD MEASUREMENTS ……………………………………………………………… 45
8.1.1
STORM SELECTION AND TRACKING ………………………………………………………………………………………….. 45
8.1.2
STORM MONITORING EQUIPMENT MAINTENANCE…………………………………………………………………….. 46
8.1.3
PREPARING STORMWATER MONITORING EQUIPMENT FOR STORM SAMPLING ………………………………. 49
8.1.4
STORMWATER GRAB SAMPLING ……………………………………………………………………………………………….. 53
FINAL QAPP
SAND FILTER SIDEWALK VAULT BMP
November 1, 2018
Page | vii
8.1.5
STORMWATER SAMPLE COLLECTION AND PROCESSING ……………………………………………………………… 55
8.1.6
MONITORING EQUIPMENT DATA DOWNLOAD ………………………………………………………………………….. 57
8.1.7
SEDIMENT ACCUMULATION RATE ……………………………………………………………………………………………. 57
8.1.8
FALLING HEAD TEST ………………………………………………………………………………………………………………. 59
8.2
CONTAINERS, PRESERVATION METHODS, HOLDING TIMES…………………………………………………………. 60
8.3
EQUIPMENT DECONTAMINATION …………………………………………………………………………………………….. 62
8.4
SAMPLE IDENTIFICATION …………………………………………………………………………………………………………. 62
8.5
CHAIN OF CUSTODY ……………………………………………………………………………………………………………….. 62
8.6
FIELD LOG REQUIREMENTS ……………………………………………………………………………………………………… 63
9.0
MEASUREMENT PROCEDURES ……………………………………………………………………………………………….. 64
9.1
PROCEDURES FOR COLLECTING FIELD MEASUREMENTS ……………………………………………………………… 64
9.2
LABORATORY PROCEDURES ……………………………………………………………………………………………………… 64
9.3
SAMPLE PREPARATION METHODS…………………………………………………………………………………………….. 66
9.4
SPECIAL METHOD REQUIREMENTS……………………………………………………………………………………………. 66
9.5
LAB(S) ACCREDITED FOR METHODS ………………………………………………………………………………………….. 66
10.0 QUALITY CONTROL ………………………………………………………………………………………………………………….. 67
10.1
FIELD QC REQUIRED ……………………………………………………………………………………………………………….. 67
10.2
LABORATORY QC REQUIRED ……………………………………………………………………………………………………. 68
10.3
CORRECTIVE ACTION ………………………………………………………………………………………………………………. 68
11.0 DATA MANAGEMENT PLAN PROCEDURES ………………………………………………………………………….. 70
11.1
DATA RECORDING & REPORTING REQUIREMENTS ……………………………………………………………………… 70
11.2
ELECTRONIC TRANSFER REQUIREMENTS …………………………………………………………………………………… 70
11.3
LABORATORY DATA PACKAGE REQUIREMENTS …………………………………………………………………………. 71
11.4
PROCEDURES FOR MISSING DATA…

EASTERN WASHINGTON
STORMWATER EFFECTIVENESS STUDIES
TECHNICAL EVALUATION REPORT (TER)
SAND FILTER SIDEWALK VAULT BMP
Study Classification: Structural BMP
Study Objective(s):  Evaluate Effectiveness  Develop New BMP
February 3, 2021
Prepared For:
Spokane County
Public Works Department
1116 W. Broadway Avenue
Spokane, Washington 99260
(509)477-3600
Prepared By:
Osborn Consulting, Inc.
101 S Stevens St.
Spokane, Washington 99201
(509)867-3654
TECHNICAL EVALUATION REPORT
February 2021
Page | ii
QAPP and TER Publication Information
The project Quality Assurance Project Plan (QAPP) and Technical Evaluation Report will be
stored
and
accessible
the
public
the
Spokane
County’s
website:
https://www.spokanecounty.org/918/Stormwater-Utility. For questions regarding the project,
please contact Matt Zarecor by email [email protected] or phone (509) 477-7255.
TER Authors and Contact Information
Aimee Navickis-Brasch, P.E., Ph.D.
Engineering Manager
Osborn Consulting, Inc.
101 S Stevens St.
Spokane, WA 99201
[email protected]
(509) 995-0557
Taylor Hoffman-Ballard, P.E.
Stormwater Engineer
Osborn Consulting, Inc.
101 S Stevens St.
Spokane, WA 99201
[email protected]
(952) 836-7863
TECHNICAL EVALUATION REPORT
February 2021
Page | iii
DOCUMENT HISTORY
This study was conducted following the QAPP which can be accessed at the link on the previous
page. The study started in October 2018 and the last data was collected in December 2020. The
draft Technical Evaluation Report (TER) was presented and submitted to the Technical Advisory
Group (TAG) in January 2021 for review and comment. Appendix Q of the TER contains a
summary of the TAG’s comments along with a summary of response to the comments including
how they were addressed in this document. The final TER was submitted to Ecology in January
2021.
TECHNICAL EVALUATION REPORT
February 2021
Page | iv
DISTRIBUTION LIST
Name, Title
Organization
Contact Information:
E-mail, Telephone
Jake Saxon,
Project Manager
Spokane County
[email protected]
509-477-7245
Matt Zarecor
Assistant County Engineer
Spokane County
[email protected]
509-477-7255
Bill Gale
Stormwater Utility Manager
Spokane County
[email protected]
509-477-7261
Ethan Murnin
Stormwater Engineer
Spokane County
[email protected]
509-477-7261
Bill Aukett
Stormwater Program
Manager
City of Moses Lake
[email protected]
509-764-3792
Shilo Sprouse
Stormwater Services
Program Manager
City of Pullman
[email protected]
509-432-9052
Nigel Pickering
Research Assoc. Professor
Washington State
University
[email protected]
509-335-8624
Drew Woodruff
City Engineer
City of West
Richland
[email protected]
509-967-5434
Doug Howie,
WQ Project Manager
Department of
Ecology
[email protected]
360-407-6444
Karen Dinicola,
WQ Project Manager
Department of
Ecology
[email protected]
360.407.6550
Brandi Lubliner,
WQ Project Manager
Department of
Ecology
[email protected]
360.407.7140
Adriane Borgias,
WQ Project Manager
Department of
Ecology
[email protected]
509-329-3515
Amanda Mars,
WQ Program – ERO
Department of
Ecology
[email protected]
509-329-3554
Aimee Navickis-Brasch,
Engineering Manager
Osborn Consulting,
Inc.
[email protected]
509-995-0557
Taylor Hoffman-Ballard,
Stormwater Engineer
Osborn Consulting,
Inc.
[email protected]
952-836-7863
Kathy Sattler, Laboratory
Project Manager
Anatek Labs
[email protected]
509-838-3999
Medhanie Tecle,
Engineering Manager
Materials Testing &
Consulting, Inc.
[email protected]
360-534-9777
TECHNICAL EVALUATION REPORT
February 2021
Page | v
1.0
TABLE OF CONTENTS
DOCUMENT HISTORY ……………………………………………………………………………………………………………………….. III
DISTRIBUTION LIST …………………………………………………………………………………………………………………………… IV
1.0
TABLE OF CONTENTS …………………………………………………………………………………………………………………. V
2.0
EXECUTIVE SUMMARY ……………………………………………………………………………………………………………….. 1
3.0
INTRODUCTION ……………………………………………………………………………………………………………………………. 4
3.1
INTRODUCTION TO THE STRUCTURAL BMP …………………………………………………………………………………… 4
3.2
PROBLEM DESCRIPTION ……………………………………………………………………………………………………………… 8
3.3
PROJECT GOALS AND OBJECTIVES ……………………………………………………………………………………………….. 8
3.4
PROJECT OVERVIEW …………………………………………………………………………………………………………………… 9
3.5
STUDY LOCATION ……………………………………………………………………………………………………………………. 10
4.0
SAMPLING PROCEDURES ………………………………………………………………………………………………………….. 12
4.1
TYPES OF DATA COLLECTED ……………………………………………………………………………………………………… 12
4.2
SAMPLE COLLECTION PROCESS ………………………………………………………………………………………………….. 14
5.0 DATA QUALITY ASSESSMENT ………………………………………………………………………………………………….. 17
5.1
DATA VERIFICATION ………………………………………………………………………………………………………………… 17
5.2
DATA USABILITY ASSESSMENT ………………………………………………………………………………………………….. 18
6.0
RESULTS AND DISCUSSION ………………………………………………………………………………………………………. 21
6.1
BMP DESIGN AND MAINTENANCE GUIDANCE ……………………………………………………………………………… 21
6.2
WATER QUALITY DATA ANALYSIS …………………………………………………………………………………………….. 25
6.3
COMPARISON OF RESULTS TO TAPE TREATMENT PERFORMANCE GOALS ………………………………………… 30
6.4
BMP DESIGN FLOW …………………………………………………………………………………………………………………. 38
6.5
OPERATION AND MAINTENANCE (O&M) CYCLE ………………………………………………………………………….. 40
7.0
FUTURE ACTION RECOMMENDATIONS ………………………………………………………………………………….. 43
8.0
CONCLUSIONS ……………………………………………………………………………………………………………………………. 44
9.0
REFERENCES ………………………………………………………………………………………………………………………………. 45
10.0 APPENDICES ……………………………………………………………………………………………………………………………….. 46
APPENDIX A. LABORATORY ANALYTICAL REPORTS ………………………………………………………………………………….. 47
APPENDIX B. STORM REPORTS ……………………………………………………………………………………………………………….. 48
APPENDIX C. DATA QUALITY ASSESSMENT ……………………………………………………………………………………………… 49
APPENDIX D. STATISTICAL AND DATA ANALYSIS ……………………………………………………………………………………… 65
TECHNICAL EVALUATION REPORT
February 2021
Page | 1
2.0
EXECUTIVE SUMMARY
The focus of this study is to evaluate the stormwater treatment performance of a new potential best
management practice (BMP) referred to as the sand filter sidewalk vault. This BMP fits in a 4-foot
by 5-foot vault installed below the sidewalk that receives runoff through a curb cut located in the
street gutter. The sand filter media consists of 18-inches of coarse sand overlaid by a coconut coir
mat. This BMP is being evaluated to provide jurisdictions with more options for retrofit or
redevelopment projects located in built urban areas where available space (right of way) for new
BMPs is limited. The proposed BMP is a variation of the basic sand filter vault BMP as defined
by the Ecology stormwater manuals for Washington State. The primary differences between the
sand filter sidewalk vault and the basic sand filter BMPs include: the proposed BMP can be
installed underneath the sidewalk (usually within the existing right of way) and is designed to
accept runoff from a larger contributing basin area.
The goal for this study is to evaluate the effectiveness of the proposed BMP. Effectiveness will be
based upon:
• The ability of the BMP to infiltrate stormwater during the 6-month 24-hour storm event
without overflowing into the bypass system within the maintenance cycle.
• The efficacy of the BMP to reduce the concentrations of total suspended solids (TSS),
dissolved copper (Cu) and zinc (Zn), and oils, which will be evaluated to determine
whether the BMP can achieve the respective Ecology treatment goals.
The goals for this study were achieved by conducting flow-through column testing and field testing
of the BMP. The flow-through column testing was conducted to develop the BMP design and
maintenance guidance prior to installation in the field. This work is described in the study QAPP
Section 3.3. The field testing was conducted at a test site in Spokane County. Automated
equipment installed at the test site was used to collect composite influent and effluent water quality
samples, flow rate, temperature, and precipitation depth. The water quality parameters tested
included the required and screening parameters defined in Technology Assessment Protocol
Ecology (TAPE) for basic, dissolved metals, and oil treatment. The physiochemical properties of
the sand filter media and sediment accumulated on top of the media were also analyzed. The media
infiltration rate was measured continuously using the data collected from the automated equipment
and twice using a modified falling head test.
The test site was constructed in 2016 and field testing was conducted from October 2018 to
December 2020. In January of 2019 (three months after testing started), the BMP failed due to the
large quantity of solids deposited on top of the sand filter media which inhibited infiltration. The
sand filter sidewalk vault design was re-evaluated, and the test site was modified to provide a pre-
settling basin to reduce the quantity of solids entering the vault. The contributing basin area was
also reduced. In June of 2019, a new sand filter media was installed in the sidewalk vault. Sample
collection re-started in the summer of 2019 and continued through November 2020. Maintenance
was performed in February 2020 to improve infiltration.
Samples were collected from a total of 24 storm events. For each of these events, a storm report
was created, and the data was evaluated to determine whether the storm met the TAPE qualifying
TECHNICAL EVALUATION REPORT
February 2021
Page | 2
storm criteria and sample collection criteria. These criteria define the minimum storm depth and
duration, storm antecedent and post storm dry period, minimum number of aliquots, sample event
coverage, and minimum number of samples. The evaluation results determined that 11 storm
events met the TAPE criteria for qualifying conditions and 8 met all the qualifying conditions
except for one or two of the criteria. The remaining storm events did not meet the criteria for three
or more qualifying conditions.
The collected data was analyzed to determine the effectiveness of the proposed BMP. The specific
objectives completed to meet the study goal are summarized below along with the results.
Objective 1: Define the BMP design and maintenance guidance for the test site.
Prior to the start of the field study, the BMP design and maintenance guidance were developed for
the proposed BMP. The guidance was based on column testing results (QAPP Section 3.3) and
modified design guidance outlined in the Eastern Washington Stormwater Management Manual
for the basic sand filter BMP (Ecology, 2019). A specification was developed for a sand filter
media (and followed to construct the test site) with a design infiltration rate of 50 inches/hour and
a hydraulic loading of 1.6 gallons per minute. The target contributing basin area for each sand
filter sidewalk vault was 3,500 sq.ft. for a site with a mean annual precipitation (MAP) of 18-
inches. Reference Section 6.1 for a complete description of the guidance.
Objective 2: Determine the pollutant removal efficiency of the BMP by measuring and comparing
the pollutant concentrations in the influent and effluent.
The average pollutant removal efficiencies were calculated for TSS, TPH (oils), and dissolved
copper and zinc. The average pollutant removal efficiency was 53.4% (TSS); -17.8% and 28.0%
(dissolved copper and zinc respectively), and 16.6% (TPH). The results of the statistical analysis
indicated a statistically significant difference between influent and effluent concentrations for TSS
and dissolved zinc. However, the influent and effluent concentrations difference is statistically
insignificant for dissolved copper and TPH.
Objective 3: Determine whether the treatment performance goals were achieved by comparing
study results to TAPE goals and requirements.
The sand filter sidewalk vault BMP did not meet the TAPE treatment performance goals for Basic,
Dissolved Metals, or Oils Treatment.
Objective 4: Establish a design hydraulic loading rate in gallons per minute per square foot of the
sand filter surface area.
The design hydraulic loading rate of 1.6 gpm/sq.ft. was developed through column testing prior to
the start of this study. This hydraulic loading rate was assessed in comparison to the measured
loading rate, TSS treatment performance, and bypass flows to determine if the rate was appropriate
for the site. Based on this evaluation, the proposed 1.6 gpm/sq.ft. hydraulic loading rate was
recommended for the design of sand filter sidewalk vault.
Objective 5: Determine the maintenance cycle frequency using the results from infiltration testing.
TECHNICAL EVALUATION REPORT
February 2021
Page | 3
The maintenance frequency was determined using infiltration and precipitation data…