D3.1 Chapter 3 Comment Responses
Commenter, Jurisdiction
Section
Comment and Suggested Revision
Comment Response
Larry Schaffner, Thurston County
3.1
"Since this is already covered in Chapter 1, is it necessary here too?
Alternatively, you might consider removing that section from Chapter 1
and covered the applicable in each of the chapters."
Included applicable MS4 Permit requirements in Chapter 3 for readers
who do not read every chapter of the guidance manual and to prevent
readers from have to flip back to Chapter 1 to review requirements.
Added reference to Appendix 1-A.
Amy B. Waterman, Ecology
3.1
"Called "high priority areas" in Phase I"
Received email from Ecology on 10/8/2024 with direction to use "priority
areas".
Abbey Stockwell, Ecology
3.6
"consider including this list here"
Reorganized chapter structure so Section 3.6 appears before Section 3.5.
Added text to Section 3.2.1 explaining areas of concern are not required
by the MS4 Permits.
Amy B. Waterman, Ecology
3.2
"We used the language "meet any of the following criteria" to make it
clear this wasn't an "and" in the sense that areas had to meet both of
these criteria."
Revised text to "Priority areas, as described by the MS4 Permits, include
curbed municipal streets that discharge to MS4 outfalls meeting any of
the following criteria: high-traffic roadways such as arterials or
collectors; and streets serving commercial or industrial land uses."
Larry Schaffner, Thurston County
3.4
"I suggest separating out data recommendations for assessing curbed
municipal streets discharging to outfalls that meet the high traffic streets
and streets serving commercial or industrial land use area criteria. This
would constitute the minimum to meet Permit expectations.
Presenting other data considerations would come into play should the
jurisdiction op to fold in additional criteria in setting priorities. Perhaps
these could be introduced in the “Other Considerations for Selecting
Priority Areas for Street Sweeping” section."
Separated the data recommendations into two lists: one for meeting MS4
Permit requirements and the other for additional considerations/areas of
concern.
Larry Schaffner, Thurston County
3.4
"If in compliance with the Permit, jurisdictions should have mapped the
associated drainage areas for tributary conveyances to all known outfalls
with a 24-inch nominal diameter or larger, or an equivalent cross-
sectional area for non-pipe systems. "
This is a new requirement for the EWA Permit. Propose no change.
Larry Schaffner, Thurston County
3.4
"This would be data associated with an additional consideration."
Receiving water data is necessary for MS4 Permit requirements. Propose
no change.
Larry Schaffner, Thurston County
3.4
"These would data associated with additional considerations."
Included data under additional considerations list.
Larry Schaffner, Thurston County
3.4
"Note: At least one know error exists in a figure in this guidance
document. I believe it has been brought to Ecology’s attention."
Noted. Thank you.
Abbey Stockwell, Ecology
3.4
"Be clear that this info is associated with the additional considerations
listed above "areas of concern" which may be beyond permit
requirements for priority areas"
Separated the data recommendations into two lists: one for meeting MS4
Permit requirements and the other for additional considerations/areas of
concern.
Amy B. Waterman, Ecology
3.4
"Seems like it would be helpful to note permit-required data."
Added "(Required by MS4 Permits)" to the mapping items required by the
Phase I and the EWA and WWA Phase II Permits.
Amy B. Waterman, Ecology
3.4
"Note that this mapping guidance will be updated."
Noted. Thank you.
Larry Schaffner, Thurston County
3.5
"Suggest using this subsection for the content appearing Section 3.6 –
Other Considerations for Selecting Priority Areas for Street Sweeping. "
Reorganized chapter structure so Section 3.6 appears before Section 3.5.
Page 1
D3.1 Chapter 3 Comment Responses
Commenter, Jurisdiction
Section
Comment and Suggested Revision
Comment Response
Larry Schaffner, Thurston County
3.6
"As suggested above, I suggest moving this in the spot currently occupied
by subsection 3.5.4 as a means to improve the organization flow of the
information and process presented."
Reorganized chapter structure so Section 3.6 appears before Section 3.5.
Amy B. Waterman, Ecology
3.6.5
"Commercial land uses already covered in earlier section."
Deleted Central Business Districts section.
Larry Schaffner, Thurston County
3.3.1
"To improve readability, rather than integrating references into
parentheticals, consider using an endnote approach instead."
Revised citation style to IEEE (in-text citations, numbered in square
brackets, which refer to the full citation listed in the references at the end
of the chapter).
Amy B. Waterman, Ecology
3.3.1.1
"We considered using AADT or ADT (actually went out with in Draft), but
got push back on availability."
We are providing this guidance as one resource Permittees can use to
identify high-traffic roadways if the data is available.
Amy B. Waterman, Ecology
3.3.1.1
"We found, in looking into this, that many municipalities have their own
classifications and definitions, which is why we left it open to how
Permittee's define. In addition to WSDOT, which is mentioned later in this
chapter, Seattle's classification may be a local example to share."
Added City of Seattle's street classifications as an example of detailed
street classifications.
Larry Schaffner, Thurston County
3.3.1.2
"Should this be “adjacent land use”? “Connecting land use”?"
Revised text to "connecting land use".
Larry Schaffner, Thurston County
3.3.1.2
"Are their also studies available that collected samples to evaluate runoff
from adjacent land uses?"
Yes, this information is available and will be incorporated into Chapter 2.
Added a reference to Chapter 2 in this section.
Larry Schaffner, Thurston County
3.3.1.2
"Does the literature report anything regarding bacteria?"
Added sources of bacteria to Table 3-2.
Abbey Stockwell, Ecology
3.3.1.2
"the permit doesn't require residential areas – unless they are associated
with high traffic streets"
Section 3.3 describes information we found in available literature, which
includes information about sweeping residential streets. This section
does not relate to Permit requirements. Permittees may consider
sweeping some residential streets, such as tree-lined streets, as part of
the their program, going above and beyond Permit requirements.
Amy B. Waterman, Ecology
3.3.1.2
"Seems like Ecology's S8 Data Characterization Study (2015) is a useful
reference here as well:
https://apps.ecology.wa.gov/publications/SummaryPages/1503001.html
Thank you for providing this resource. We plan to incorporate this
resource into Chapter 2.
Larry Schaffner, Thurston County
3.3.1.3
"Suggest integrating this subsection’s content into Section 3.6."
This section describes information found during the literature search, so
it belongs in this section. Reorganized chapter structure so Section 6.3
appears after applicable Permit requirements and before Section 3.5.
Amy B. Waterman, Ecology
3.3.1.3
"Address how this would fit with Permit required priority areas."
Section 3.3 describes information we found in available literature
regarding street sweeping. This section does not directly relate to Permit
requirements. Some Permittees may choose to include other areas of
concern as part of their street sweeping program to meet specific
jurisdictional needs/goals.
Larry Schaffner, Thurston County
3.5.1
"Is this in reference to the March 31, 2028 deadline to map MS4 tributary
basins to outfalls with a 24” nominal diameter or larger, or an equivalent
cross-sectional area for no-pipe systems that have SW treatment and
flow control BMPs/facilities owned or operated by the Permittee
[S4.b.iii.]? If so, should this matter since the Permit already requires
ongoing mapping of their associated drainage areas [i.e. S4.C.4.a.v.(b)]?
In other words, doesn’t MS4 tributary basins = associated drainage areas
This is a new requirement for the EWA Permit. Revised text to specify EWA
Permit.
Page 2
D3.1 Chapter 3 Comment Responses
Commenter, Jurisdiction
Section
Comment and Suggested Revision
Comment Response
Larry Schaffner, Thurston County
3.5.1
"Impervious surface cover???"
Revised text to "impervious surface cover".
Abbey Stockwell, Ecology
3.5.1
"it is unclear which mapping requirement is being referred to here.
consider striking"
Revised text to “Mapping tributary conveyances to outfalls…”. This
section was also revised to indicate this is only a new mapping
requirement in the EWA Permit.
Amy B. Waterman, Ecology
3.5.1
"? list of or link to?"
Revised text to “with resources provided at the end of this section.”
Abbey Stockwell, Ecology
3.5.1
"recommend removing reference to "point of compliance" in figure – this
is not a term used with the muni permit"
We hope to replace this figure with an example map from a Permittee.
Larry Schaffner, Thurston County
3.5.2
"The link goes to an FHWA document."
Revised text to "FHWA".
Christian Nilsen, GeoSyntec
3.1
"Suggest a brief statement on why this step is important. Something brief,
like 'to target areas with the greatest potential for improvement
permittees should identify priority areas for sweeping.""
Added "This information can assist Permittees with targeting areas with
the greatest potential for water quality improvement."
Larry Schaffner, Thurston County
3.5.3
"Are there any Permittees that don’t have a zoning maps?"
Most jurisdictions probably have zoning maps, but we would like to
provide resources in case they may be useful.
Larry Schaffner, Thurston County
3.5.4
"As mentioned above, I suggest renaming this subsection and using this
spot for the information presented in Section 3.6."
Reorganized chapter structure so Section 3.6 appears before Section 3.5.
Larry Schaffner, Thurston County
3.5.4
"A reasonable interpretation would be that the Permit’s two criteria in
S5.4.e.i. (of the WWA Phase II permit) define the baseline for this
expectation. Anything else would be additional considerations."
Deleted the first two sentences of the original paragraph.
Larry Schaffner, Thurston County
3.5.4
"As mentioned above, it would be helpful to integrated Section 3.3.1.3
content into Section 3.6."
Reorganized chapter structure so Section 3.6 appears before Section 3.5.
Zack Holt, Bremerton WA
3.5.4
"On page 3-9 section 3.5.4. consider including the National Wetland
Inventory maps and the IPaC wildlife planning maps from USFWS, the
WDFW PHS dataset, WDFW’s fish passage inventory maps, Ecology’s
Washington State Coastal Atlas, Local jurisdiction zoning maps (for
commercial areas, etc.) and DNR’s NHD database for critical areas
information, environmentally sensitive areas and waterbodies."
Added the suggested resources to Section 3.5.4.
Abbey Stockwell, Ecology
3.5.4
"To clarify, this does not mean we expect Permittees to identify other
areas than what is required for priority areas. This section should be clear
that these are other areas for consideration – not required by permit."
Deleted the first two sentences of the original paragraph.
Amy B. Waterman, Ecology
3.5.4
"Again, this is not in the permit priority area designation."
Yes, areas of concern have been described as optional.
Page 3
D3.1 Chapter 3 Comment Responses
Commenter, Jurisdiction
Section
Comment and Suggested Revision
Comment Response
Larry Schaffner, Thurston County
3.5.3
"Our senior land use planner suggests a couple of methods.
Method 1 uses zoning and future land use designations. The caveat
being, not all the parcels may be currently developed and used of
commercial or industrial land uses, and there may be industrial of
commercial land uses elsewhere not captured by this approach.
Method 2 uses the assessor’s most recent parcel data. The caveat being,
while this reflects current use of the property, it doesn’t capture areas
zoned for commercial or industrial uses into the future."
Added, "Municipalities may also use assessor parcel data to identify
zoning. Since zoning can change, it is recommended that the jurisdictions
consult with their planning department to identify if and where future
zoning and land use designation changes may occur."
Larry Schaffner, Thurston County
3.6.1
"Could also consider tree-lined streets as its own category."
Revised "these areas" to "tree-lined" streets.
Christian Nilsen, GeoSyntec
3.6.3
"If including areas where construction activity is important, there should
be some mention of the construction general permit. Outline
requirements of construction permittees vs municipal permittees. "
No revisions made as the construction general permit is outside the
scope of this manual.
Larry Schaffner, Thurston County
3.5.5
"Might be more helpful to depict this using the relevant GIS coverages
described above."
We will work on updating this figure for the draft manual either with a
jurisdiction's figure or one we create.
Larry Schaffner, Thurston County
3.6.6
"Is doesn’t seem like the correct section reference?"
Revised to Section 3.3.1.3.
Shelly Basketfield, SPU
overall
"please revise pine needles with conifer needles."
Revised all instances of "pine needles" to "conifer needles".
Don McQuilliams, Bellevue WA
overall
"Good morning Laurie, I have review chapters 1 and 3 and both are well
done. I didn’t have any specific comments or changes that jumped out at
me at first review. Seems pretty straight forward."
Thank you for your review.
Page 4

Street Sweeping Manual
8-1
Chapter 8. STREET SWEEPING COST CONSIDERATIONS
8.1
Chapter Introduction
This chapter is designed to help Permittees determine the funding and resources needed to
implement an effective street sweeping program. It begins with an overview of the procedure for
assessing funding requirements, defining influential cost factors (Section 8.2.1) in relation to
program elements and discussing how to identify program needs and allocate resources (Section
8.2.2). The structure of the program will influence the required resources, including staff, materials,
and equipment (Section 8.2.3). Users should first review these sections to understand how
resource needs are determined and apply this process to the cost-driving program components
discussed in Section 8.2.4. This chapter also details how to calculate the required FTEs and
funding to meet a program’s needs (Section 8.3). Using the guidance of this chapter, the user
should be able to answer the following question: What resources and funding are required to meet
each program need? This chapter also details different street sweeping funding sources and
describes the cost considerations of in-house versus contracted street sweeping. The intended use
of Sections 8.2 and 8.3 are described in in the bulleted process shown below:
First, review Sections 8.2.1 through 8.2.3 to understand how resource needs are
determined.
Next, review each component in Section 8.2.4 while considering program needs as
determined in the former sections (Sections 8.2.1 through 8.2.3).
Once necessary resources have been determined, review and perform the calculations in
Section 8.3 to estimate the number of full-time staff equivalents (FTEs) and the costs of
labor, equipment, and materials required to operate the street sweeping program.
This chapter intends to serve as a starting point for estimating resource needs. Since the chapter’s
guidance may not encompass all jurisdictions’ individual needs, the reader should review these
sections and identify which components apply. There may also be unique items specific to a
jurisdiction that are not identified in this chapter but should be added to estimate funding needs.
The contents of this chapter are meant to be used jointly with Appendix 8-A, which is a calculator
tool that uses resource quantities (materials, equipment, and staff) needed to operate each
program component to calculate total staff and funding needs. Sheet 2-Staffing Options and
Sheet 3-Equipment and Materials in the calculator detail the resources needed to operate the
program elements outlined Sheets 4-11. Please refer to Sheet 0-Instructions for additional details
regarding the use of this tool. Finally, refer to Sheet 1-Funding Summary to gather total staff and
funding estimates to satisfy all program needs. Table 8-1 details the cost-driving program
components detailed in this chapter and their corresponding calculator sheet(s).
Chapter 8
Street Sweeping Cost Considerations
Street Sweeping Manual
8-2
Table 8-1. Chapter Sections and Corresponding Calculator Sheets
8.2
Program Needs and Resource Allocation
8.2.1 Defining Cost-Driving Program Components
Planning for and developing a new municipal street sweeping program begins with identifying
jurisdictional goals, which may be influenced by meeting Phase I or Phase II MS4 Permit
requirements, safety or maintenance concerns, public expectations, and/or water quality concerns
such as TMDLs or proximity to salmon habitats. Once defined, these goals will inform which
program elements are implemented. Jurisdictions should consult Section 4.3 to determine which
street sweeping elements are needed to achieve permit requirements and their jurisdiction’s
program goals.
The street sweeping program elements were used to inform cost-driving program components,
where cost-driving program components are defined as the specific elements or activities within
the program that contribute to the overall expenses. Examples of cost-driving program components
are shown in Table 8-2. While some of these directly reflect program elements, others were refined
or added because of their direct impact on cost [1, 2].
The applicable program elements selected in Chapter 4 will inform which components will
influence the expenses of a jurisdiction’s street sweeping program. The following subsection
includes typical cost-driving program components associated with street sweeping programs.
8.2.2 Identifying Program Needs and Allocating Resources
Identifying and understanding the needs of the street sweeping program is necessary to allocate
resources and funding. Program needs are the street sweeping program components necessary to
meet a jurisdiction’s program goals. Resources are the staff, materials, and equipment to meet the
street sweeping program needs.
Section 8.2.4 includes a list of information to consider when determining resource needs for each
program component. When reviewing these considerations, municipal staff should estimate the
time needed to implement each program component, as well as the frequency of tasks, or amount
of material or equipment required to allow for estimation of funding and staffing needs (shown in
Chapter Section
Corresponding Calculator Sheet(s)
8.2.2 – Allocating Resources
Sheet 2 – Staffing Options
Sheet 3 – Materials and Equipment
Error! Reference source not found. – Scheduling
Sheet 4 – Scheduling
8.2.4.2 – Administration and Program Management
Sheet 5 – Administration
8.2.4.3 – Operations and Maintenance
Requirements
Sheet 6 – Maintenance Quals & Training
8.2.4.4 – Parking Regulation and Enforcement
Sheet 7 – Regulation and Enforcement
Error! Reference source not found. – Education and
Outreach
Sheet 8 – E&O
8.2.4.6 – Documentation and Reporting
Sheet 9 – Documentation & Reporting
8.2.4.7 – Insurance, Damage Claims, and Workers’
Compensation
Sheet 10 – Insurance, Damage & WC
8.2.4.8 – Street Waste Disposal
Sheet 11 – Disposal
Chapter 8
Street Sweeping Cost Considerations
Street Sweeping Manual
8-3
Section 8.2.3). A gap-analysis can be a helpful tool to estimate resource needs using the following
sections. A gap analysis is a process where the estimated resources needed are compared to
available resources to identify gaps between a current program and the desired future program. The
gap or discrepancy between the current and future program is the additional resources needed to
achieve program goals. Specific considerations include:
Identified staff needed to operate the program element, including the type of staff
members, their experience, specialties, and wages, including overhead rates. Reference
Section 4.3.2 for more details.
The amount of time required by each staff type to achieve program goals and implement
each element, as well as staff availability (this will inform the number of FTEs required to
achieve program goals).
o Time required by staff members can be estimated using records from previous years
or by contacting jurisdictions of a similar size.
o FTE values can also be estimated using literature values as described in Section
8.2.
Materials and equipment necessary to operate each program element, including the start-
up costs to establish a program as well as the ongoing costs associated with program
upkeep.
Table 8-2 provides some example program resources, which may help jurisdictions fulfill program
needs and can be used to assist with resource allocation.
Table 8-2. Example Resources for Establishing and Maintaining a Street Sweeping Program
1Items that fall under start-up equipment and material needs may also be ongoing.
8.2.3 Additional Considerations
8.2.3.1 Contracted Services
If Permittees utilize contracted services for sweeping, some responsibilities and requirements will
shift, as does the allocation of cost. For example, if the contractor owns the equipment, they may
also assume responsibility for its maintenance and repair. A jurisdiction will need to review their
specific contract or define their needs in a request for proposals (RFP) and ensure all costs are
accounted for in their fees to the contractor or within their own budget. Alternative duties such as
Resources to Meet Program Needs
Examples
Staff Types
Administrative Staff, Junior and Lead Operators,
Engineers, Traffic Control Officers, Crew Leaders,
Contracted Drivers, Mechanics, etc.
Start-Up Equipment and Materials1
Cost of Equipment, Storage Space, Office Overhead
Equipment, Uniforms, Repair Kits, Paper for Fliers,
GPS to GIS Systems, Cameras, Real-Time Notification
System, Ticketing Materials, etc.
Ongoing Equipment and Materials
Fuel, Oil, Insurance Costs, Water (Washing), Disposal
Costs, Software Licensing, Cleaning Materials, Paper
for Fliers, Routine/Nonroutine Maintenance Costs,
Ticketing Materials, Repairs, Equipment
Replacements, etc.
Chapter 8
Street Sweeping Cost Considerations
Street Sweeping Manual
8-4
contract management, inspecting and evaluating contractor work, and coordination with the
contractor will become the responsibility of the municipal staff, and the in-house resources will
need to accommodate this workload. However, regardless of whether in-house or contracted
services are utilized, many responsibilities and their associated costs will remain for expenses such
as scheduling, software licensing, and education and outreach. The required resources,
responsibilities, and costs must be carefully considered when deciding whether to operate a street
sweeping program entirely in-house or to hire a contractor.
8.2.3.2 Cross-Training
In some cases, employees are cross-trained to fulfill street sweeping duties as well as other
jurisdictional duties. For example, the City of Mukilteo has four staff members cross-trained to
operate street sweeping equipment among other responsibilities, enabling the City to effectively
administer and operate its street sweeping program. Some eastern Washington jurisdictions have
reported cross-training street sweeping operators to run the snowplow in the winter. Cross-training
employees can result in cost savings if street sweeping duties can be combined with other
municipal needs, minimizing the need to hire additional staff. Cross-training can also improve job
satisfaction and prevent burnout by incorporating variety into employee work.
8.2.4 Cost-Driving Program Components
The following subsections review various cost-driving program components, which each correlate
with a portion of Appendix 8-A’s calculator (please reference Table 8-1 for the sheets that correlate
with each chapter section). Each subsection highlights items specific to its respective program
component that may influence expenses. Additional considerations to assist users in estimating
costs associated with each program component can be found in the corresponding calculator
sheet for that component. The funding calculator uses the quantities of materials, equipment, and
hours needed to operate each program component to calculate total staff and funding needs.
Error! Reference source not found. – Scheduling
8.2.4.2 – Administration and Program Management
8.2.4.3 – Operations and Maintenance Requirements
8.2.4.4 – Parking Regulation and Enforcement
Error! Reference source not found. – Education and Outreach
8.2.4.6 – Documentation and Reporting
8.2.4.7 – Insurance, Damage, Workers’ Compensation
8.2.4.8 – Street Waste Disposal
In addition to this manual, it is recommended that jurisdictions apply existing street sweeping data
(if available) to supplement the tools provided. Permittees can use existing records and collected
data to assist in estimating program needs and identifying any unique items as they review each
subsection, if available. For example, if a jurisdiction’s program is broken out to a level of detail
showing what was previously spent on specific street sweeping elements, this data can be used to
estimate future funding needs by scaling up program costs to include any missing components. If
existing records or data are unavailable, Permittees can use information from literature or contact
other jurisdictions to help inform their cost estimations. Section 8.3.2.1 includes example cost
information from literature and discussion with Washington jurisdictions. Either way, Permittees
Chapter 8
Street Sweeping Cost Considerations
Street Sweeping Manual
8-5
should collect information that will assist them with estimating quantities of resources, time
required to complete tasks, and frequency of tasks to meet program needs. This information will be
used to develop a cost estimate as detailed in Section 8.3.
8.2.4.1 Scheduling
Standardized scheduling can help jurisdictions determine the staff, equipment, and materials
necessary to operate their planned routes at their desired frequency and help allocate resources to
maximize cost efficiency. Section 4.3.3 contains additional details about scheduling. Refer to
Sheet 4-Sweeping Routes in the calculator (Appendix 8-A) for detailed calculations related
specifically to scheduling. Street sweeping route considerations to help inform the cost estimation
include:
Identifying streets to be swept and determining routes (see Section 5.5 for additional
guidance)
Dividing streets into routes that operators can sweep efficiently
The amount of time to sweep each route
Sweeper utilization (time sweeping during regular shift vs. other tasks such as traveling to
dispose of waste)
Sweeping route frequency
Determining when each route is going to be swept
These estimations can help determine the number of curb miles swept, amount of staff time
required to sweep routes, and costs of completing sweeping routes.
8.2.4.2 Administration and Program Management
Municipal street sweeping program administrative responsibilities include establishing policies and
procedures, managing staff and budgets, and coordinating with regulatory and other municipal
departments. Reference Section 4.3.1 for more information on administrative responsibilities.
Refer to Sheet 5-Administration (Appendix 8-A) for the calculations related to administrative
responsibilities. When estimating administrative costs, consider the time, staff, and resources
needed to:
Develop and implement policies, procedures, resolutions, and ordinances
Coordinate with other departments
Recruit, hire, and train street sweeping staff and/or develop a request for proposals (RFP),
hire contractors, and manage contracts
Acquire funding, track expenses, and maintain budgets
Update sweeping routes, schedules, and protocols
8.2.4.3 Operations and Maintenance Requirements
Street sweeping programs require funding for training maintenance staff and performing equipment
maintenance, repair, and replacement. Reference Section 4.3.4 for recommended operations and
maintenance protocols and Section 4.3.7 for additional details about training.
Use Sheet 6-Maintenance Quals. & Training (Appendix 8-A) for detailed calculations related to
operations and maintenance requirements. Consider the following when estimating…

Street Sweeping Manual
3-1
Chapter 3. IDENTIFY PRIORITY STREET SWEEPING AREAS
3.1
Chapter Introduction
The Phase I and Phase II MS4 Permits require Permittees to designate priority areas for street
sweeping. This chapter provides guidance to support Permittees in identifying their priority areas.
The first section of this chapter includes a literature synthesis that compiles available information
on criteria and approaches for selecting priority areas by jurisdictions with developed street
sweeping programs. The chapter then describes applicable MS4 Permit requirements, as well as
additional factors Permittees may consider while selecting street sweeping priority areas based
on unique jurisdictional priorities and environmental goals. This information can assist Permittees
with targeting areas with the greatest potential for water quality improvement. Lastly, the chapter
provides guidance on selecting priority areas to meet MS4 Permit requirements using information
from the literature synthesis.
3.2
Literature Synthesis
This section synthesizes approaches for identifying and selecting priority areas for street sweeping
based on documents examined during a literature review. Section 3.6 applies this information to
develop an approach Permittees may use when developing or modifying their street sweeping
programs. Sources for the literature review included research reports, case studies of municipal
street sweeping programs, and guidance materials from across the United States.
3.2.1 Criteria for Selecting Priority Street Sweeping Areas
Based on case studies and numerous street sweeping guidance manuals, the most common
criteria recommended for identifying high-priority roadways for street sweeping include traffic
volume, roadway class, adjacent land use, and proximity to areas of concern such as sensitive
environmental areas [1, 2, 3, 4, 5, 6]. For example, a survey of 36 municipalities located in the
Chesapeake Bay Watershed, conducted by Schueler et al., found that respondents selected streets
for sweeping based on traffic volume (45%), land use (50%, of which 45% specifically targeted
commercial areas), residential demand (40%), proximity to environmentally sensitive areas (10%),
and pollutant loading rates (5%) [2]. The following subsections include details about the most
common criteria and their justification. The criteria in Sections 3.2.1.1 and 3.2.1.2 are consistent
with the criteria for priority areas identified in the MS4 Permits. Section 3.2.1.3 includes criteria
that are not included in the MS4 Permit definition of priority areas. These areas of concern, which
Permittees may choose to also include in their street sweeping program, were identified in the
literature as conditions that may increase pollutant generation or need additional protection.
3.2.1.1 Traffic Volume
Vehicular transportation-related activities constitute a major source of pollution in stormwater
runoff. While researchers report conflicting results regarding whether a correlation exists between
traffic volumes and pollutant loading, many researchers recommend using traffic volumes as a
planning tool for prioritizing stormwater management [7, 8, 9, 10]. See Chapter 2, Section 2.2.2,
for additional information. In addition, a study by Schilling conducted in 2005 surveyed 60
municipalities throughout Minnesota, the U.S., and Canada to identify trends in street sweeping
practices and develop policy recommendations. Municipalities primarily targeted arterial and
Chapter 3
Identify Priority Street Sweeping Areas
Street Sweeping Manual
3-2
collector roads for street sweeping activities due to their higher traffic volumes and greater
pollutant-generation potential [6]. Given this information and the information presented in Section
2.2.2, high-traffic roadways are recommended to include as priority areas for street sweeping.
High-traffic streets can be identified by using traffic volumes (e.g., annual average daily traffic
[AADT] data), if available, or roadway classifications. The primary roadway classifications relevant
to municipal street sweeping programs include arterials, collectors, and local roads, which may be
designated as secondary and tertiary roads [11, 4]. Table 3-1 summarizes roadway classifications
and associated AADT estimates for use in identifying roadways for street sweeping.
Table 3-1. Roadway Classifications and AADT Estimates
Road
Classification
Description
AADT Usage
AADT Reported
Ranges
Arterials
High-traffic roads that primarily function as
interconnecting pathways between
different areas, providing limited access to
adjacent land areas
High
Rural: 1,500–8,500
Urban: 3,000–27,000
Collectors
Medium-traffic roads that serve to connect
arterials to local roads
Medium
Rural: 150–2,600
Urban: 1,100–6,300
Local Roads
(Secondary &
Tertiary Roads)
Low-traffic roads that provide the greatest
access to adjacent lands, businesses, and
residences
Low
Rural: 15–400
Urban: 80–700
Sources: [4, 11] Note: This table is intended to be used as a guideline; jurisdictions may utilize their own roadway classifications and
definitions, if available.
Some jurisdictions have chosen to break down their roadway classifications into more detailed
categories, which can be used to design street sweeping routes and frequencies. See Section 2.3
of the City of Seattle’s Right-of-Way Improvements Manual for an example of detailed street
classifications (2.3 Street Classification :: Seattle Streets Illustrated).
3.2.1.2 Land Use
Connecting land use is a key indicator of potential pollutant pathways to streets, with certain land
uses known to be associated with greater street waste and pollutant accumulation (see Chapter 2,
Section 2.2.2) [12, 13]. Furthermore, roadway type and traffic volume often correlate to connecting
land use [6]. As such, contributing land use types are considered a primary factor in prioritizing
street sweeping areas. Error! Reference source not found. summarizes land use types and
associated pollutant pathways along with suggested sweeping priority.
The primary contributing land uses considered for street sweeping in the reviewed literature include
industrial, commercial, and residential. Roadways adjacent to industrial areas are predicted to
generate more sediment and pollutants than other land areas (see Chapter 2 for discussion of
pollutant generation from different land uses). This is due to the increased presence of heavy
industrial vehicles as well as the potential tracking or spillage of granular and polluting materials
from industrial sites and transport vehicles [13, 12]. Commercial land areas are also commonly
targeted for street sweeping due to their high traffic volume, which is associated with greater
pollutant generation [14, 15]. Moreover, industrial and commercial land areas are often connected
Chapter 3
Identify Priority Street Sweeping Areas
Street Sweeping Manual
3-3
via arterial roads, which commonly results in these zones being grouped together for street
sweeping prioritization [6]. In contrast, residential areas, generally served by secondary and tertiary
local roads, experience lower traffic volumes, and the roads may not be curbed, so they are
generally not included in target areas [12, 15, 6]. Though residential land areas usually experience
low traffic, they are sometimes prioritized for street sweeping due to concerns over emissions of
nutrients and other organic contaminants [2, 16]. For example, residential zones may have denser
vegetation and tree canopy cover, which results in a higher ratio of organic debris in street waste.
Reference Section 3.4.1 for additional information about residential areas.
Table 3-2. Land Use Types and Sweeping Priority
Land Use Type
Common Pollutants
Major Pollutant Sources
Sweeping
Priority
Industrial
Heavy metals, industrial by-
products, sediments, vehicle
wear by-products, Particulate
Matter (PM)
Stormwater runoff, atmospheric
deposition, tracking and spillage
from heavy vehicles
High
Commercial
Vehicle emissions, vehicle wear
by-products, PM, bacteria
High traffic volume, sewer and
stormwater systems, stormwater
runoff, atmospheric deposition
High
Residential
Nutrients, herbicides, pesticides,
bacteria
Leaf drop, yard waste, pet and
wildlife waste, stormwater runoff
Low–Medium
Sources: [6, 12, 16, 17] 3.2.1.3 Areas of Concern
Areas of concern are localized features that may increase pollutant generation or heighten
sensitivity to environmental impacts. Examples of areas of concern include:
Dense tree canopy areas – Areas with a high presence of trees, which can cause leaves or
conifer needles to seasonally fall onto the street. Leaf litter and other organic detritus can
contribute to nutrient contamination in street waste and stormwater [18]. Additionally,
leaves and conifer needles can clog stormwater structures, potentially disrupting
stormwater networks and resulting in flooding [15].
Known or likely spillage sites – Areas with a history of spill or illicit discharge complaints
and areas that store large quantities of materials that could elevate the risk for illicit
discharges or spills [19].
Potential pollutant-generating industrial sites – Areas containing industries with high
potential for pollutant emissions (including aerial) that can accumulate on roads. These
industries may include vehicle operations, waste management, site maintenance, outdoor
materials storage, and landscaping. Improper storage or disposal practices at these types
of industrial sites can increase the risk of spills, resulting in tracking or wash-off of
contaminants onto roadways [20].
Impaired or sensitive receiving waters – Water bodies that do not fully support their
beneficial uses [21, 22], such as those with known impairments (303[d] listings), or
receiving waters with sensitive aquatic life. These receiving waters may experience a greater
detrimental impact from transported street waste.
Chapter 3
Identify Priority Street Sweeping Areas
Street Sweeping Manual
3-4
Critical areas – Areas that are designated and protected to preserve their function such as
wetlands, fish and habitat conservation areas, and aquifer recharge areas [21, 22]. These
areas may experience a greater detrimental impact from transported street waste.
Several studies identify these areas as “hot spots” and recommended considering hot spots when
prioritizing street sweeping locations [6, 1, 23, 12], with one study recommending that identified hot
spots be the first priority for establishing street sweeping areas [6]. Hot spots are land areas or
features that contribute elevated pollutant loads or experience greater impacts from pollutant
loads [6]. During winter and early spring, roadways that receive winter maintenance applications
may be considered hot spots due to the increased street waste loading and potential surface water
contamination from deicers or other maintenance materials (see Chapter 4 for winter weather
considerations). Areas with periods of high potential pollution-generation activity, such as parades,
fairs, color runs, or other events, are also considered hot spots and may be considered when
setting street sweeping priorities and schedules. For example, the City of Puyallup sweeps its
fairgrounds every day during their Fall and Spring Fair. The City also sweeps the routes into and out
of its Daffodil Parade and Santa Parade, as well as the parade routes [24].
3.3
Applicable Requirements
It is recommended for Permittees to begin identifying priority areas by considering applicable local
and MS4 Permit requirements specific to street sweeping. Street sweeping programs are often
implemented by municipal departments other than stormwater, such as transportation or public
works. Therefore, if a street sweeping program already exists in the Permittee’s jurisdiction,
Permittees should consult the responsible department to understand local street sweeping
policies. Required sweeping areas designated by local policies should be included in the priority
areas. Permittees should also include priority areas identified in the MS4 Permits, described in the
following section.
3.3.1 Applicable MS4 Permit Requirements
The Phase I and Phase II MS4 Permit requirements for street sweeping specify the designation of
priority areas, 90 percent of which must be swept three times (four times for the Phase I Permit)
annually, with one of the sweeping events occurring between July and September [19, 25, 26].
Priority areas, as described by the MS4 Permits, include curbed municipal streets that discharge to
MS4 outfalls meeting any of the following criteria: high-traffic roadways such as arterials or
collectors, and streets serving commercial or industrial land uses. The selection of priority areas
must provide the highest likelihood of water quality improvements to receiving waters. The Phase I
and Phase II MS4 Permits also require Permittees to submit a map of swept priority areas with the
Annual Report beginning in March 2028 [19, 25, 26]. Appendix 1-A provides details of the street
sweeping requirements for each MS4 Permit.
3.4
Other Considerations for Selecting Priority Areas for Street Sweeping
Though traffic volume and land use are defined criteria for selecting priority street sweeping areas
in the MS4 Permits, jurisdictions may have additional priorities and environmental goals they wish
to consider. This section describes additional factors Permittees may consider while selecting
Chapter 3
Identify Priority Street Sweeping Areas
Street Sweeping Manual
3-5
street sweeping priority areas. These factors are known to increase sediment accumulation rates or
produce more severe environmental or social impacts.
3.4.1 Residential Areas
Jurisdictions with active street sweeping programs sometimes choose to also prioritize residential
areas due to additional debris and pollutants from yard care and increased street tree canopy
density (deciduous or evergreen trees). For receiving waters prone to nutrient impacts, targeting
areas with higher organic matter in street waste may justify prioritizing residential areas for street
sweeping. For tree-lined streets, it is most beneficial to schedule sweeping around periods of
significant leaf or conifer needle drop, such as fall and spring [2]. Chapter 5 further describes street
sweeping scheduling.
3.4.2 Near-Shore Areas
Coastal areas are particularly vulnerable to nutrient contamination and are especially impacted
by near-shore residential lawn runoff [12]. Permittees may consider targeting near-shore areas with
dense tree cover, lawn areas, or areas of known heavy fertilizer use for street sweeping activities.
Furthermore, street sweeping may be a highly efficient and effective mitigation strategy for
stormwater runoff impacting important species of salmon and orca whales in the Puget Sound area
[27]. Coastal jurisdictions located adjacent to major surface waters and their tributaries may
consider prioritizing near-shore areas for street sweeping activities in a…