Press Alt + R to read the document text or Alt + P to download or print.
This document contains no pages.
HomeMy WebLinkAbout4344 Resolution - 2023 Stormwater Management PlanRESOLUTION NO.4344
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF PASCO,
WASHINGTON, ADOPTING THE 2023 COMPREHENSIVE STORMWATER
MANAGEMENT PLAN.
WHEREAS, the City of Pasco (City) owns and operates a Municipal Separate Storm
Sewer System (MS4) utility that provides stormwater mitigation measures for the publicly owned
rights -of -way; and
WHEREAS stormwater discharges to surface waters are strictly regulated by the
Washington State Department of Ecology (DOE) National Pollutant Discharge Elimination
System (NPDES — a section of the Federal Clean Water Act) program; and
WHEREAS, the City is a Phase II Eastern Washington Municipal Stormwater Permittee,
subject to the rules and regulations of the DOE NPDES program; and
WHEREAS, the City recognizes the need to safeguard and preserve Washington's waters
for clean drinking water, and the protection of fish, shellfish, wildlife, and public health; and
WHEREAS, the City's consultant, Herrera Environmental Consultants, Inc., has studied
the City's MS4 and has developed a management plan designed to ensure regulatory compliance
with the City's Phase II Eastern Washington Municipal Stormwater Permit.
NOW, THEREFORE, BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY
OF PASCO, WASHINGTON:
That the City Council hereby adopts the 2023 Comprehensive Stormwater Management
Plan prepared by Herrera Environmental Consultants, Inc., attached hereto as Exhibit A, to be
used as a guide by staff and Council in making various decisions about the City's Stormwater
Management Program.
PASSED by the City Council of the City of Pasco, Washington, on this I" day of May,
2023.
anche Barajas
Mayor
ATTEST:
Debra Barham, CMC
City Clerk
Resolution — Stormwater Management Plan Adoption - 1
EXHIBIT A
CITY OF PASCO
COMPREHENSIVE
STORMWATER MANAGEMENT PLAN - 2023
Prepared for
City of Pasco
City 1
JP'4�iSCO
Public Works Department
Prepared by
Herrera Environmental Consultants, Inc.
(kjA
HERRERA
Note:
Some pages in this document have been purposely skipped or blank pages inserted
so that this document will print correctly when duplexed.
CITY OF PASCO
COMPREHENSIVE
STORMWATER MANAGEMENT PLAN - 2023
Prepared for
City of Pasco
7M
VS co
1I'
Public Works Department
525 North Third Avenue
Pasco, Washington 99301
Prepared by
Herrera Environmental Consultants, Inc.
2200 Sixth Avenue, Suite 1100
Seattle, Washington 98121
Telephone: 206-441-9080
March 7, 2023
This page intentionally left blank
This Comprehensive Stormwater Management Plan was produced through the combined
efforts, ideas, and cooperation of the following City of Pasco staff, appointed and elected
officials, and consultants.
City Staff
Michael Henao
Project Manager/Environmental Compliance Coordinator
Maria Serra
Deputy Public Works Director
Derek Wiitala
Public Works Division Manager
Herrera Environmental Consultants
Joy Michaud
Rebecca Dugopolski
Matt Fontaine
Julianne Chechanover
Lacy Lackey
Meghan Mullen
Lauren Ode -Giles
Rebecca Stebbing
Pam Jackowich; Michelle Fox
Project Manager/Plan Development
Data Gaps and Needs Assessment
CIP Prioritization and Design
Study Area Characterization, Data Gaps and Needs
Assessment, and CIP Prioritization and Design
CIP Prioritization and Design
CIP Prioritization and Design
Geographic Information Systems
Geographic Information Systems
Word Processing
HERRERA
pU cc_21-07654-000_2023_pascocompswplan_20230307.docx
This page intentionally left blank
CONTENTS
Acknowledgements......................................................................................................................................................... i
Acronymsand Abbreviations...................................................................................................................................vii
1. Introduction..............................................................................................................................................................1
1.1. Purpose of this Plan.....................................................................................................................................2
1.2. Program Goals and Policies......................................................................................................................3
1.2.1. General Stormwater Management Program Goals.....................................................3
1.2.2. Flow Control Goals..................................................................................................................4
1.2.3. Water Quality Goals................................................................................................................4
1.2.4. Funding Goals............................................................................................................................4
1.3. Stormwater Plan Development................................................................................................................4
2. Study Area Characteristics..................................................................................................................................7
2.1. Environmental Setting (topography, geology, and soils)............................................................10
2.2. Land Use/Land Cover................................................................................................................................11
2.3. Water Resources..........................................................................................................................................18
2.4. Critical Areas and Species........................................................................................................................19
2.4.1. Groundwater Resources......................................................................................................20
2.4.2. Wetlands, Riparian Buffers, and Habitat........................................................................22
2.4.3. Geologic and Flood Hazard Areas...................................................................................22
2.5. Future Conditions.......................................................................................................................................25
2.5.1. Population Growth................................................................................................................25
2.5.2. Climate Change.......................................................................................................................25
3. Stormwater Management Framework.........................................................................................................27
3.1. Stormwater Infrastructure and Operations and Maintenance...................................................27
3.2. Applicable Regulations.............................................................................................................................29
3.3. Municipal Code and Design Standards..............................................................................................31
3.4. Stormwater Utility Fund............................................................................................................................33
3.4.1. History and Purpose..............................................................................................................33
3.4.2. Past and Current Use of Funds.........................................................................................35
3.4.3. Population Growth................................................................................................................35
3.4.4. Annexation................................................................................................................................35
3.4.5. Climate Change.......................................................................................................................35
4 HERRERA
p0 cc_21-07654-000_2023,pascocompswplan 20230307docx
4. Stormwater System Problems, Prioritization, Solutions, and Implementation .............................37
4.1. Problem Identification and Prioritization...........................................................................................37
4.1.1. Risk Definition — Flooding Infrastructure......................................................................42
4.1.2. Risk Definition — Deteriorating Infrastructure.............................................................42
4.1.3. Other Criteria...........................................................................................................................43
4.2. Problems.........................................................................................................................................................43
4.2.1.
Flooding.....................................................................................................................................43
4.2.2.
Deteriorating Conveyance Infrastructure......................................................................44
4.2.3.
Lack of Water Quality Treatment.....................................................................................45
4.3. Solutions
.........................................................................................................................................................46
4.3.1.
Infiltration Improvements...................................................................................................48
4.3.2.
Conveyance Infrastructure Rehabilitation
.....................................................................50
4.3.3.
Water Quality Protection.....................................................................................................51
5. Stormwater Management Program Evaluation and Recommended Activities ............................53
5.1. Public Education and Outreach.............................................................................................................54
5.2. Public Involvement and Participation..................................................................................................56
5.3. Illicit Discharge Detection and Elimination.......................................................................................57
5.4. Construction Site Stormwater Runoff Control.................................................................................61
5.5. Post -Construction Stormwater Management..................................................................................63
5.6. Municipal Operations and Maintenance............................................................................................64
5.7. Total Maximum Daily Load Requirements........................................................................................66
5.8. Monitoring and Assessment...................................................................................................................66
5.9. Reporting and Recordkeeping...............................................................................................................66
5.10. Update to City Code and Design Standards.........................................................................67
6. Plan Implementation...........................................................................................................................................69
6.1. NPDES Permit Timeline.............................................................................................................................69
6.2. Staffing Needs..............................................................................................................................................69
6.3. Equipment Needs.......................................................................................................................................71
6.4. Capital Improvement Program Needs................................................................................................73
6.5. Interdepartmental Collaboration..........................................................................................................75
6.6. Interagency Collaboration.......................................................................................................................76
7. References...............................................................................................................................................................77
4 HERRERA
pj cc_21-07654-000 2023_pascocompswplan 20230307docz
APPENDICES
Appendix A City of Pasco Stormwater Management (SWM) Program Questionnaire
Appendix B Stormwater Management Program Evaluation and Recommended Activities
Appendix C Project Summary Sheets and Cost Estimates
TABLES
Table 2-1.
City of Pasco Basin Characteristics.........................................................................................10
Table 2-2.
Land Use Descriptions and Land Area Percent Within Pasco City Limits in
2021....................................................................................................................................................12
Table 2-3.
Land Use Within Pasco Basin Boundaries............................................................................14
Table 2-4.
Critical and Hazardous Areas Within Pasco by Basin......................................................23
Table 3-1.
Stormwater Infrastructure Within Pasco by Basin............................................................27
Table 3-2.
Summary of Applicable Regulations......................................................................................29
Table 3-3.
City of Pasco Stormwater Utility Monthly Rates from 2002 to Present....................34
Table 4-1.
Categorization of Site -Specific Problems.............................................................................37
Table 4-2.
Stormwater Code Violations.....................................................................................................46
Table 4 3.
Tier 1 Problems and CIP Solutions..........................................................................................46
Table 4-4.
CIP Project/Program Descriptions and Capital Costs......................................................50
Table 5-1.
Recommended Activities for Public Education and Outreach.....................................54
Table 5-2.
Recommended Activities for Public Involvement and Participation ..........................56
Table 5-3.
Recommended Activities for Illicit Discharge Detection and Elimination...............57
Table 5-4.
Recommended Activities for Construction Site Stormwater Runoff
Control...............................................................................................................................................61
Table 5-5.
Recommended Activities for Post -Construction Stormwater
Management...................................................................................................................................63
Table 5-6.
Recommended Activities for Municipal Operations and Maintenance ....................64
Table 6-1.
NPDES Permit Timeline...............................................................................................................69
Table 6-2.
Current and Recommended City of Pasco SWMP Staff and Consultant
Needs to Support Ongoing Activities...................................................................................70
Table 6-3.
Current and Recommended City of Pasco SWMP Equipment.....................................71
Table 6-4.
Capital Improvement Program Implementation Schedule.a.........................................74
Table 6-5.
Interdepartmental Responsibilities.........................................................................................75
* HERRERA
py cc 21-07654-000_2023.pascocompswplan 20230307.docx
FIGURES
Figure 2-1.
Vicinity Map of Pasco and Area Covered by this Plan......................................................8
Figure 2-2.
Stormwater Subbasin Boundaries, City of Pasco................................................................9
Figure 2-3.
Land Use Within the City of Pasco..........................................................................................13
Figure 2-4.
Zoning Within the City of Pasco..............................................................................................16
Figure 2-5.
Impervious Surfaces in the City of Pasco.............................................................................17
Figure 2-6.
Groundwater and Critical Areas Within the City of Pasco.............................................21
Figure 2-7.
Flood and Steep Slope Hazards Within the City of Pasco.............................................24
Figure 3-1.
Stormwater Infrastructure in the City of Pasco..................................................................28
Figure 4-1 (a).
CIP Prioritization Process............................................................................................................39
Figure4-1 (b).
Site Prioritization...........................................................................................................................40
Figure 4-1 (c).
CIP Prioritization Process Comparison..................................................................................41
Figure 4-2.
CIP Project Locations Within the City of Pasco..................................................................49
vi
HERRERA
pj cc 21-07654-000 2023_pascocompswplan 20230307doa
ACRONYMS AND ABBREVIATIONS
BMP
best management practice
CARA
Critical Aquifer Recharge Area
CCTV
closed-circuit television
CIP
capital improvement program
City
City of Pasco
Ecology
Washington State Department of Ecology
ESA
Endangered Species Act
FEMA
Federal Emergency Management Agency
FIRM
Flood Insurance Rate Map
FTE
full-time equivalent
GIS
Geographic Information Systems
IDDE
Illicit Discharge Detection and Elimination
LID
low impact development
MS4
Municipal Separate Storm Sewer System
PMC
Pasco Municipal Code
NPDES
National Pollutant Discharge Elimination System
O&M
operations and maintenance
Phase II Permit
Eastern Washington Phase II Municipal Stormwater Permit
PMC
Pasco Municipal Code
SEPA
State Environmental Policy Act
SR
State Route
SWMMEW
Stormwater Management Manual for Eastern Washington
SWMP
Stormwater Master Program
SWPPP
stormwater pollution prevention plan
TMDL
Total Maximum Daily Load
UGA
Urban Growth Area
UIC
underground injection control
USACE
United States Army Corps of Engineers
U.S. EPA
United States Environmental Protection Agency
WHPA
wellhead protection area
6 HERRERA vii
pj cc-27-07654-000_2023_pascocompswplan 2023030Zdocz
This page intentionally left blank
1. INTRODUCTION
Stormwater runoff can be a source of pollutants to surface water and groundwater, can cause
erosion and flooding, and can result in damage to property. Therefore, managing stormwater is
an important aspect of city government. While, historically, stormwater management was
primarily relegated to management of underground pipes and conveyance networks to enhance
draining and reduce flooding, it is now recognized that stormwater plays many roles. It is a
source of pollutants, but it is also an important resource critical to maintaining streamflows and
recharge of groundwater. As a consequence, stormwater management at a city level has
become more complex and includes many components, such as maintaining the system of
pipes, catch basins, and treatment devices; offering programs to educate residents and
businesses about reducing pollutants; creating ways to remove pollutants; and conducting a
broad range of maintenance activities.
Stormwater is recognized as a critical source of pollutants by the federal government and is
regulated by federal law through the Clean Water Act. The National Pollutant Discharge
Elimination System (NPDES) is the program that addresses water pollution via discharge of
pollutants from sources such as stormwater. In Washington State, the NPDES program is
administered by the Washington State Department of Ecology (Ecology) through authorization
from the United States Environmental Protection Agency (U.S. EPA). The City of Pasco's (City)
stormwater program is regulated via Ecology's Phase II Eastern Washington Municipal
Stormwater Permit (NPDES permit). That NPDES permit includes extensive requirements related
to stormwater program management, system design requirements, operations and maintenance
(O&M), and more. Section S of this Comprehensive Stormwater Management Plan details the
specific requirements of the NPDES permit and their impact on development of this plan. One of
the purposes of this plan is to lay out a program that meets the City's needs, including those
driven by the NPDES permit.
Due to the city's low annual rainfall, warm climate, flat topography, and fast -draining soils, most
of the stormwater generated in the city infiltrates the ground either through natural processes
or manmade structures, such as dry wells and infiltration trenches. The result is that flooding,
erosion, and slope failures that are often associated with high volumes of stormwater runoff are
not as critical in Pasco as they may be in other areas of Washington. However, stormwater
quality remains an important issue because water quality concerns are driven by population and
land use (e.g., commercial and industrial businesses). The City's reliance on infiltration of
stormwater means that underlying groundwater is more vulnerable to contamination, especially
because of the area's fast -draining soils. Since Pasco's drinking water is supplied by
groundwater, the City needs to protect groundwater quality while maintaining groundwater
recharge processes. The semi -arid climate also means that stormwater should be viewed as an
important resource to protect and conserve. This comprehensive plan for managing stormwater
reflects the unique features of Pasco's environment. The first comprehensive stormwater plan for
the City of Pasco was developed in 2016; this document provides an update to that plan.
March 2023
City of Pasco Comprehensive Stormwater Management Plan — 2023
* HERRERA
1.1. PURPOSE OF THIS PLAN
The purpose of this plan is to guide the City's stormwater management program in a manner
consistent with current regulatory requirements, while also identifying highest priority
stormwater problems and solutions, and developing a timeline for implementation of both the
regulatory requirements and the stormwater solutions. The plan also identifies the resources
(financial, staffing, and equipment) needed for implementation that is consistent with the
revenue generated by the City's stormwater management utility. The following describes the
content of each section of the plan with a summary of the extent of the updates made between
the previous (2016) plan and this version:
• Section 1: Establishes the purpose of the plan and stormwater management goals for the
City. There have been minor refinements of the goals as part of this update.
• Sections 2 and 3: Provide background information on the Pasco area, the existing
stormwater system, and the existing stormwater management program. There have been
updates to much of the tabular data and some of the figures to reflect changes in the
area covered by this plan as well as other changes that have occurred since the 2016
plan.
• Section 4: Describes proposed solutions to high priority stormwater issues. This section
has been entirely revised from the 2016 plan to reflect the newly identified stormwater
problems and solutions.
• Section 5: Identifies minimum actions necessary to ensure compliance with applicable
federal, state, and local requirements, especially the City's NPDES permit. This section has
been entirely revised from the 2016 plan to reflect the revisions to the NPDES permit
that have occurred since 2016 as well as to reflect changes in staffing and operations at
the City.
• Section 6: Provides a plan for implementation that identifies resource needs and focuses
on efficient use of limited resources. This edition of the plan does not include an
assessment of the current utility rate but reflects a balance of revenue and resource
needs.
Stormwater management involves maintaining and replacing stormwater infrastructure and
building new stormwater facilities to meet development needs and to replace infrastructure that
has come to the end of its service life. Stormwater management is a continually evolving field,
driven by changes in state and federal stormwater regulations as well as by changes in science
and technology. This means it can be technically and financially challenging to accommodate
program needs while balancing utility ratepayer costs. This plan will need to be updated
periodically to reflect the changing landscape of stormwater management and issues specific to
the City of Pasco.
'C% IHERRERA March 2023
City of Pasco Comprehensive Stormwater Management Plan — 2023
1.2. PROGRAM GOALS AND POLICIES
Goals and policies were developed to guide the development of this plan that are consistent
with the City's goals. They support actions that will ensure stormwater is managed efficiently,
protect the quality and quantity of water resources, and protect groundwater, which is the City's
drinking water source. The stormwater goals in this section were developed to clarify and
document the City's priorities related to stormwater management.
1.2.1. General Stormwater Management Program Goals
G1. Meet the minimum regulatory requirements of the Eastern Washington Phase II
NPDES Municipal Stormwater Permit while protecting local natural resources.
G2. Continue to support regional efforts to address stormwater management.
G3. Continue to be cost effective. Meet at least the minimum requirements of the NPDES
permit, meet the needs of the public, and be strategic about addressing long-term
operational deficiencies.
G4. Proactively maintain, repair, rehabilitate, and replace aging City stormwater facilities
and minimize the need for costly and disruptive emergency repairs. Be strategic to
the extent possible and plan repairs around other City projects (e.g., roadwork).
G5. Continue to provide public education (including to outreach to businesses) on
stormwater and water resource issues and support for the City's stormwater
management program.
G6. Ensure that new development, redevelopment, and City projects are in conformance
with the City's adopted stormwater requirements and flow control goals.
G7. Coordinate with other City departments throughout the stormwater plan review,
permitting, and project approval process to ensure that the process results in a
functional stormwater system.
G8. Oversee construction and maintenance of privately owned stormwater facilities to
ensure that they function as designed to protect private property, public property,
and the environment.
G9. Develop written protocols, where needed, to demonstrate compliance with NPDES
permit requirements.
G10. Revise this Comprehensive Stormwater Management Plan every 6 years, or sooner if
needed, to ensure that it provides for effective long-term stormwater project
planning, system maintenance, response to mandates, and program funding.
March 2023
4 HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
1.2.2. Flow Control Goals
FC1. Develop new drainage projects to address flooding problems when such problems
cannot be addressed through maintenance of the existing infrastructure.
FC2. Continue to encourage and allow the use of infiltration facilities for flow control for
new development and redevelopment in accordance with current regulations, and
where feasible.
1.2.3. Water Quality Goals
WQ1. When practicable, add or improve water quality treatment whenever constructing
new stormwater facilities or conducting maintenance, repair, rehabilitation, or
replacement of aging City stormwater facilities.
WQ2. Protect groundwater resources by regulating land use activities, such as requiring
a higher level of stormwater treatment within wellhead protection areas, and
encouraging practices that minimize impacts to groundwater.
■ Develop guidance and public outreach materials for use of chemicals (pesticides,
herbicides, or fertilizers) near infiltration facilities.
1.2.4. Funding Goals
F1. Implement a stormwater program that balances resource, staffing and project needs
with the revenue generated by the utility and with the staffing resources available.
F2. Control costs through proactively identifying stormwater problems to reduce the
need for emergency response.
F3. Maintain low stormwater utility rates while ensuring that the fees collected
adequately cover the costs of implementing stormwater program needs.
1.3. STORMWATER PLAN DEVELOPMENT
Significant research was conducted to provide a foundation for development of this plan. The
2016 plan and capital improvement plan (CIP) list was reviewed to determine what has been
completed. Geographic information system (GIS) data were acquired from city, county, state,
and national datasets. This included information on the existing storm drainage system
infrastructure, which was derived mostly from GIS data provided by the City. Questionnaires,
multiple workshops with City staff, camera logs of pipelines, a web -based stormwater problems
map, and field surveys were used to supplement this information.
4 HERRERA
March 2023
City of Pasco Comprehensive Stormwater Management Plan — 2023
The first workshop for development of this plan occurred on December 17, 2021. A
questionnaire was distributed in advance of the first workshop to gather staff input and
perspectives on a consistent set of questions. The completed questionnaires were used to
facilitate the workshop discussion of NPDES permit requirements, staffing needs, funding needs,
and other issues of concern to City staff. A comparison table of NPDES permit requirements and
the City's current program was developed and used with the completed questionnaires to
develop Section 5 of this plan. Appendices A and B provide a complete list of permit
requirements, current activities, and recommended activities, as well as a copy of the
questionnaire.
In preparation for the second workshop on January 19, 2022, a web -based stormwater problems
map was re-created from the 2016 planning effort, and City staff and the consultant team began
the process of populating the map with information on known problems and problem locations.
During the second workshop, the team reviewed the stormwater problems map and discussed
each project in further detail in preparation for project prioritization. Project prioritization criteria
were developed and discussed alongside field visit logistics during the third workshop on
February 14, 2022. Each project was ranked high, medium, or low based on a quantitative
analysis. Project prioritization criteria included flooding frequency and severity, maintenance
level of effort, pipe defects, and other factors.
A field review of key problem areas was conducted with City staff on March 11, 2022. During this
field assessment, detail was collected on specific sites. Photos and observations from the field
review and assessment were used to finalize the project rankings. The highest ranked projects
were developed to a concept -level design with associated planning -level cost estimates and the
information was used to create project summary sheets, which are included as Appendix C.
Simultaneous to the development of this plan, City staff identified one additional CIP project,
the Schlagel Park Stormwater Main Replacement project. This has been included as a high
priority project to be completed within the next few years; however, there are currently no
design details and therefore no project summary sheet for this project.
A number of the projects identified address infiltration improvement needs and did not rank
high as individual projects. However, an annual program to address infiltration improvements
has been included for budget planning purposes, and many of these projects have been
identified as priorities in that program. Similarly, there are numerous areas within the city where
stormwater conveyance pipes need to be replaced or relined. A Stormwater Pipe Lining Project
[Phases 1 and 2] has also been included in the CIP list and implementation schedule in this plan.
This plan was first completed in 2022, but then modified to encompass a larger project area that
includes the entire urban growth area (UGA), West Pasco, and small inholdings within the city
limits that are currently within Franklin County's jurisdiction; but it does not include the area that
falls under the Port of Pasco's NPDES permit. This change was made to better reflect the City's
responsibilities.
March 2023
4 HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 5
This page intentionally left blank
2. STUDY AREA CHARACTERISTICS
Pasco is located in south-central Washington on the Columbia River, near the confluence of the
Columbia and Snake Rivers. The area spanned by the city is approximately 37 square miles.
Pasco's population was over 78,000 as of 2021. It is the county seat for Franklin County.
Together with the cities of Kennewick, Richland, and West Richland, Pasco forms the
"Quad -Cities" area of Eastern Washington. The Quad -Cities are the fourth largest metro area in
the state. It is an area that has been growing fast; for example, the population in Pasco is
expected to increase to 121,828 by year 2038 (Pasco 2018).
The Quad -Cities area lies within what is known as the Central Basin region of Washington State.
This region is composed of the Columbia River Basin and adjacent low -elevation areas of central
Washington. Because of its location, Pasco enjoys a mild climate, has a long growing season,
and boasts 300 days of sunshine each year. Annual precipitation is very low; annual rainfall is
estimated at 6.5 inches and snowfall at 2.75 inches. Pasco is at a low elevation, and there is little
topographic variation. Because of the arid climate and relatively flat topography, other than the
Columbia and Snake Rivers, there are no other natural surface waters within or near the city
limits. The dry conditions, in combination with the wind, mean that windblown debris is a
common problem that affects stormwater quality as well as facility maintenance needs.
To support the City's need to plan for future growth, the area covered by this plan (Figure 2-1) is
larger than the area covered by the City's NPDES permit. The plan area covers approximately
45 square miles and has the same boundaries as the UGA, except it does not include the Port of
Pasco since that is covered by a separate NPDES permit. The Pasco city limits, UGA boundaries,
City NPDES area, and Port of Pasco NPDES area are also shown in Figure 2-1. Since the 2016
plan, over 2,800 acres have been annexed by the City. A few areas of inholdings, primarily
owned by Franklin County, still exist within the general city boundary but are part of the UGA
and therefore included in the plan area. Together, these inholdings represent approximately
2 square miles. These inholdings, in combination with the Port of Pasco (approximately 5 square
miles), represent the difference between the city limits (approximately 43 square miles) and the
UGA (approximately 50 square miles). Both the city and UGA boundaries extend to the center of
the Columbia River and, as a result, include several square miles of the river. For the purposes of
this plan, only the land area is included in the data summaries because, from a stormwater
management perspective, only the surfaces that generate runoff are relevant.
For the purpose of stormwater planning, Pasco is divided into six basins. Basins 1 through 5 are
delineated by hydrologic boundaries of the stormwater conveyance system and represent the
older part of the city. Basin 6 represents all of the area outside of Basins 1 through 5. Basin 6 is
the largest of the six basins, representing nearly 85 percent of the area within the city limits
(Figure 2-2). The Port of Pasco's industrial area is within the city limit, but is not included in basin
boundaries or stormwater planning because the Port is responsible for its own stormwater
management. Table 2-1 lists the areas and percent impervious of each of the six basins.
March 2023 ( HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
V1
lip
396
7 � '
0-- tn -A
r
I !
Pasco
Legend
Figure 2-1.
Vicinity Map of Pasco and Area
Pasco City Limits (20
Covered by this Plan.
r I Urban Growth Area
boundary (2022)
Plan Area
ri
N
City NPDES area
a Area of
map detail
o 1 4
Port of Pasco NPDES Area
v
Miles
River
X
R HERRERA
Stream
Highway
bAerial:
ESRI 2020
KWraleels1V2021121076540001Pro Pasc0_Fg— Prnlld*Vasm Fgure Pa do aM(2Q4R 23)
Legend Figure 2-2.
Pasco City limits Stormwater Subbasin Boundaries,
Urban Growth Area boundary City of Pasco.
Q Subbasin boundary N
River 0
Stream o 4,500 9,0a0 18,000
Highway --I Feet
HERRERA
Aenal: ESRI 2020
4w+q sI It W654C6. 3+oe'n[o.iw WMI41. Iw n�— rrzwn
Table 2-1. City of Pasco Basin Characteristics.
Total Area
Basin' (acres)
Within City
Limits
Area
Impervious Surface
Acres
Percent
Acres
Percent
1
1,297
1,297
100
589
45
2
872
872
100
454
52
3
187
187
100
91
49
4
1,161
1,161
100
633
55
S
277
277
100
153
55
6
25,149
20,915
83
5,359
26
Total 28,944
24,709
85
1 7,304
1 30
a Basins correspond to those delineated in Figure 2-2.
The following sections describe the environmental setting of the city, and the natural resources
intended to be protected or improved by implementation of this plan.
2.1. ENVIRONMENTAL SETTING (TOPOGRAPHY, GEOLOGY,
AND SOILS)
Topography in Pasco is predominately flat. The eastern side of the city is almost entirely flat,
with only very small, topographic variations. To the west of the airport is a small ridge, running
north to south, that rises to a plateau situated about 100 feet in elevation above the city and
slopes gently to the southeast. Most of the land area within the city drains toward the Columbia
River, though a small portion of the eastern edge drains toward the Snake River.
The ancient and recent geology of the region define both the topography and the soil drainage
properties that affect stormwater planning. Pasco is located on what is referred to as the
Columbia Plateau. The Columbia Plateau is composed of continental flood basalts that erupted
between about 16.7 and 5.5 million years ago (USGS 2016). The basalt flows near Pasco are
particularly thick and are estimated to have a depth of approximately 15,000 feet (Kahle et al.
2009). These basalt plains were further modified during the Pleistocene epoch by catastrophic
outburst floods, such as the Missoula floods, which translocated huge quantities of glacial and
fluvial sediments (Kahle et al. 2009). More recently, windblown inputs of sand and finer
sediments blanketed the landscape and compose the parent material of most of the soils found
throughout the city (NRCS 2016).
Soil drainage properties are important for stormwater planning because, to a large extent, they
determine whether rainwater will run off the land as overland flow or infiltrate down through the
soil profile. Coarser (e.g., sandy textured soils) will allow water to infiltrate faster than finer
textured soils (e.g., silty or clayey soils). Most of the soils within the city are sandy in texture
(psamments, loamy sands, or sandy loam) and are described as being excessively drained
(NRCS 2016). The entire city and UGA are listed as Hydrologic Soil Group A, which has high
V HERRER'A March 2023
10 City of Pasco Comprehensive Stormwater Management Plan — 2023
drainage/infiltration capacity (NRCS 2016). However, there are isolated, small areas within Pasco
where the soils do not infiltrate, even though they have the appearance of sand. For example, in
one geotechnical investigation, several test pits were dug along the Oregon Avenue/395
corridor and the saturated hydraulic conductivity was tested. Despite soil textures that would
hypothetically drain very rapidly, the measured saturated conductivity of the samples ranged
from 0.003 inches/hour for silty sand and 24.36 inches/hour for poorly graded sand (CH2M Hill
2014). In another investigation, the infiltration rate was measured for three test borings
approximately 8 feet below the ground surface. Infiltration rate was 12.5 and 20 inches/hour for
two of the three borings, but the third had a rate of 0 inches/hour; even though it was described
as a medium grain soil similar to the one with a 20 inch/hour rate (PBS 2014). These two studies
indicate that there are areas where infiltration may be infeasible despite the appearance of the
coarsely textured soils. The overall extent or location of these poor infiltration areas is unknown.
The fact that these soils exist only in small pockets of the city can be somewhat problematic
because area residents and the development community are accustomed to assuming that
infiltration capacity will be high.
2.2. LAND USE/LAND COVER
Land use is important for stormwater planning because it is linked with the percentage of
impervious surface that, in combination with soil drainage properties, determines the amount of
stormwater runoff generated by a parcel. Land use categories were mapped from City parcel
data. The parcel data contained 16 land use categories. For the purposes of this planning effort,
these categories were combined to create 4 general categories that include
commercial/industrial, residential, mixed use, and other. Table 2-2 describes each of the 16 land
use categories and the percentage of land area within the city attributed to each category. The
table also provides a crosswalk to the general category that has each land use category has
been assigned to. The results are displayed in Figure 2-3.
Table 2-3 provides a summary of the current land use by each of the 4 general categories in the
city by basin. The city is primarily composed of residential (46 percent) and
commercial/industrial (39 percent) lands. The rest of the city is composed of other (13 percent)
and mixed use (3 percent) land uses.
Recognizing land use patterns at the city -scale is also important for identifying how land use has
changed over time and will change in the future. For this purpose, the city can be described as
two distinct areas. Basins 1 through 5, which comprise a small percentage of the total city area
(approximately 15 percent) represent the older, more established areas of the city. Basin 6,
which represents the vast majority of land area in the city (approximately 85 percent) is the area
where most of the recent growth has occurred and is occurring.
March 2023
I� HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 11
Table 2-2. Land Use Descriptions and Land Area Percent Within Pasco City Limits in 2021.
Land Use
General
Land Area
Category
Category
Generalized Description
(percent)b
Low Density
Residential
Single-family residential development at a density of 2 to 5 dwelling
36.5
Residential
units per acre.
Industrial
Commercial/
Manufacturing, food processing, storage and wholesale distribution
22.3
Industrial
of equipment and products, hazardous material storage, and
trans ortation related facilities.
9.0
Commercial
Commercial/
Neighborhood, community and regional shopping and specialty
Industrial
centers, business parks, service and office uses.
Commercial/
Land occupied by the Tri-Cities Airport.
7.8
Airport Reserve
Industrial
Medium Density Residential
Single-family dwellings, patio homes, townhouses, apartments, and
7.0
Residential
condominiums at a density of 6 to 20 dwelling units per acre.
Open Space
Other Land where development will be severely restricted: park lands, 5.2
Parks
trails, and critical areas.
Other Schools, civic centers, fire stations and other public uses. 3.8
Public Quasi-
Public
Other Transition lands owned and presently managed by DNR for natural 3.1
DNR Reserve
resource production. Characteristics include, but are not limited to,
proximity to urban -type development, road and utility
infrastructure, and market demand.
Mixed Use Allow a combination of mixed -use residential and commercial in the 1.7
Mixed
Residential
same development. Single-family dwellings, patio homes,
Commercial
townhouses, apartments, and condominiums at a density of 5 to 29
dwelling units per acre. Neighborhood shopping and specialty
centers, business parks, service and office uses.
High Density
Residential
Multiple unit apartments or condominiums at a density 21 units per 1.1
Residential
acre or more.
Land owned by the Confederated Tribes of the Colville Reservation. 0.8
Confederated
Other
Tribes —Colville
Mixed Use
Mixed Use
Broadmoor only; general retail operations and shops, grocery 0.6
Regional
stores, residential above commercial/office, high -density residential,
dining, entertainment uses.
Office
Commercial/
Broadmoor only; professional office and personal services, resource 0.4
Industrial
centers.
Broadmoor only; single-family dwelling units, townhouses, 0.4
Medium High
Mixed Use
Density
condominiums, and multifamily; 8-15 dwelling units per acre.
Residential
Mixed Use
Mixed Use
Broadmoor only; along 1-182 corridor; commuter services, 0.1
Interchange
Mixed Use
technology and resource business parks, office, and retail uses.
Mixed Use
Broadmoor only; townhouses, multifamily developments,
0.1
Neighborhood
neighborhood grocers/markets and drug stores, vertically
integrated buildings, live/work spaces, and other neighborhood
scale offices and uses.
a Descriptions correspond to those outlined in the 2018 Pasco Comprehensive Plan Land Use Density Table.
4 !-HERRERA
March 2023
12 City of Pasco Comprehensive Stormwater Management Plan - 2023
Legend
Pasco City Limits
=.� Urban Growth Area boundary
O Subbasin boundary
1I River
Highway
Land Use Classes (Pasco 2021)
Commercial/Industrial
Airport Reserve
Commercial
Industrial
1willb-f Office
Residential
Residential - Single -Family
Medium Density Residential
Medium High Density
Residential
High Density Residential
Mixed Use
Mixed Residential Commercial
Mixed Use Interchange
Mixed Use Neighborhood
Mixed Use Regional
Other
Confederated Tribes - Colville
DNR Reserve
Open Space Parks
Public Quasi -Public
Figure 2-3.
Land Use Within the City of Pasco.
N
a
0 4,500 9,000 18,000
Feet
HERRERA
USDA, Aerial (2020)
KO§ WWY2021}21.0765A-0001Pro1P Fgure_PUMIOV— F - Pptldio.a (21712023) I
c
t
N
If
IT
N
N
N
IL
M
X_
91
�n
N'ct
N
N
Ln
c
N
d
R
d
Yl
d
ate+
O
M
c
W
N
Ln
�D
O
m
.y
fD
m
10
c
V
a
y
C
`
d
lmfl
Lin
M
N
to
M
to
M
M
c
�
•L
d
E
V
((��11
L
Q
Ol
1-
Ln
n
N
co
00
�
a
M
c
J
r
fV
c
41
m
en
Ln
rn
O
Ln
l0
Ln
O
Ln
00
f�
a1
R_
d
R
r
d
�N
y
G
a
N
n
IDM
Ln
n
t�
M
C
�
m
v
to
to
0
F
lam
ih
O
u
2
Land use in Basin 6 is predominately a mixture of residential and commercial/industrial.
Residential development represents the largest land use (approximately 48 percent) and is
concentrated on the western half of the basin (Figure 2-3). The commercial/industrial areas,
which represent approximately 36 percent of the land area within Basin 6 are primarily located
along the northeastern fringes of the city (Figure 2-3).
"*-- itar to Basin 6, Basins 1 through 5 are primarily composed of residential (between 33 and
56 percent) and co`nT""'-- ,.g1Andustrial (between 24 and 55 percent) (Table 2-3). In general,
commercial/industrial development oct_u long the major transportation corridors in the older
parts of the city. Based on current zoning regulations, ft would be expected that development
would consist of continued commercial/industrial development, predominately retail, along the
1-182 corridor (Figure 2-4).
While comparing the percentage of each land use type among the basins is useful for evaluating
development patterns, the total area of each land use type is also important. For example, based
solely on percentage comparisons, it would appear that managing runoff from
commercial/industrial land uses, which have comparatively high pollutant generation rates, is
less of an issue in Basin 6 (36 percent commercial/industrial) than in Basin 2 (55 percent
commercial/industrial). However, because Basin 6 is much larger than Basin 2 it has more than
20 times the area of commercial/industrial land uses (Table 2-3), and there are much larger
uninterrupted commercial/industrial areas in Basin 6 than in any of the other basins (Figure 2-3).
Total impervious surface coverage is an important consideration for stormwater management
and basin planning since it directly affects how much precipitation leaves the land and becomes
stormwater runoff. Impervious surface coverage is mapped on Figure 2-5. Impervious surface
area and percentage for each basin is listed in Table 2-1. Approximately 34 percent of the city is
impervious surface as illustrated in Figure 2-5; however, this estimate is biased by the much
larger area and less dense development in Basin 6. For the older parts of the city (Basins 1
through 5), the impervious surface coverage ranges from 45 to 55 percent. With continued
urban and suburban expansion into Basin 6, the percentage of impervious surface coverage can
be expected to increase.
March2023 �Jj HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 is
Legend
= Pasco City Limits
i_ 1 Urban Growth Area boundary
QSubbasin boundary
Highway
Zoning (Pasco, 2022)
R-S-12, R-S-2O, Suburban
R-S-1/PUD, Suburban PUD
R-S-1, Suburban
R-1/PUD, Lo-Density
Residential PUD
R-1, Lo-Density Residential
R-1-A, Lo-Density Residential Alt.
R-2, R-3, Med-Density Residential
R-3/PUD, Med-Density
Residential PUD
R-4, Hi -Density Residential
RP, Residential Park
R-T, Residential Transition
0, Office District
BP, Business Park
C-1, Retail Business
C-2, Central Business
C-3, General Business
C-R, Regional Commercial
I-1, Light Industrial
1-2, Medium Industrial
1-3, Heavy Industrial
[] Not Zoned
Zoning (Franklin County, 2022)
AP-20, Ag. Production 20 ac.
C-1, Retail Business
C-2, Rural Service Commercial
C-3, General Business
C-R, Regional Commercial
1-2, General Industrial
1-3, Heavy Industrial
0, Office
R-T, Residential Transition
RC-1, Rural Community 1 ac.
® RC-5, Rural Community 5 ac.
RR-1, Rural Residential 1 ac.
® RR-5, Rural Residential 5 ac.
RS-2O, Suburban
RS-4O, Suburban
Figure 2-4.
Zoning Within the City of Pasco.
N
a
0 4,500 9,000 18.000
Feet
(01t HERRERA
City of Pasco. Zoning 12022)
M VRgedsVvppp iV)� 07E5e-QWViMetPeyo F�9we PaKNnVPe�co Fez PwlloLu ewe IJV 71}IVJI
i
Ls
F _
a
au i4b`a R� `Q 5 2 12
i3.-i�,
n_
Legend Figure 2-5.
Cn Pasco City Limits NLCD Percent developed (2019) Impervious Surfaces in the City of Pasco.
Urban Growth Area boundary Imperviousness
© Subbasin boundary High : 100
-- River Low : 0 µ
Stream
0 4,500 9,000 18,000
Highway Feet
(Vij HERRERA
Aerral: ESRI 2020
C Ii . l-0]6S40.3 1,—_;—'-, rba— y.._, , .n •1WJI
2.3. WATER RESOURCES
Pasco is situated at the confluence of the Snake and Colombia Rivers. Both the Snake and
Columbia Rivers are large river systems that drain tens of thousands of square miles. The
Columbia is the sixth largest river system in the United States as measured by drainage area and
has a drainage area of approximately 258,000 square miles. The Snake River is the tenth largest,
with a drainage area of 108,000 square miles (Kammerer 1990). Neither the Columbia River nor
the Snake River adjacent to Pasco are free -flowing. McNary Dam, about 34 miles downstream of
Pasco, creates Lake Wallula, which extends 64 miles upstream on the Columbia River to Hanford,
and up the Snake River to Ice Harbor Lock and Dam (USACE 2016). Since the city limits extend
out into the rivers, both rivers are considered part of the city and addressed in the City's
Shoreline Management Plan (Anchor QEA 2014).
There is also one stream shown on Figure 2-1 is associated with the Esquatzel Coulee. This
stream was at one time included in the City's shoreline jurisdiction but was removed since there
are few or no water -related uses of the stream and because the data suggest little water exists in
the stream (Anchor QEA 2014). This stream gradually 'sinks into the ground' and does not
discharge to any downstream water bodies (Anchor QEA 2014). Figure 2-1 also shows a small
stream in the southwest corner of the city, which is actually a ditch created by the United States
Army Corps of Engineers (USACE). The ditch occasionally collects stormwater but never
discharges to the river (Dave McDonald, pers. comm. with T. Reed -Jennings). The most notable
water feature within the interior of the city is the Franklin County Irrigation District Canal, which
runs west to east through most of the city.
The U.S. EPA, in coordination with Ecology, implements and oversees monitoring programs to
ensure that waters meet state and federal water quality standards. The purpose of these
standards is to comply with the Clean Water Act, ensuring that water is safe for human contact
and healthy for fish and wildlife.
Section 303(d) of the Clean Water Act requires that waters failing to meet these standards are
placed on the list of "impaired" waters, often referred to as the "303(d) list." As of the most
recent proposed list (2018), there are a number of listings associated with the Columbia River
near Pasco. That reach of the river has documented exceedances of temperature standards and
is, therefore, listed as Category 5 for temperature. Category 5 means that a Total Maximum Daily
Load (TMDL) or other type of cleanup plan is required. The U.S. EPA is leading the effort to
develop a temperature TMDL for that reach. The reach is also listed as Category 4a for total
dissolved gas and dioxins, and Category 2 for pH. Category 4a means there is a documented
problem, but a cleanup plan is already in place. Category 2 are for water bodies of concern.
Water bodies in this category have a potential water quality problem, but there is not enough
evidence to show consistent impairment and therefore, no cleanup plan is needed.
6 HERRERA March 2023
18 City of Pasco Comprehensive Stormwater Management Plan — 2023
The Snake River near the Pasco area has these same water quality concerns and Category 4
and 5 listings. The Snake River reach was also recently included on the 303(d) list due to total
dissolved gas and dioxin. Since there is now a cleanup plan in place to address these problems,
the reach is now Category 4a for these constituents. The Snake River also has a Category 2 for
dissolved oxygen. None of these listings are expected to be strongly related to stormwater, and
neither the Columbia nor Snake River are included in Appendix 2 of the existing NPDES permit,
which lists TMDLs covered by the permit and describes additional actions permittees must take
to be in compliance with the permit.
Major changes in the state water quality standards since the 2016 plan include new human
health criteria for toxic substances adopted in 2016 and new water contact recreation bacteria
criteria (E. coli for fresh water) adopted in 2019. Human health criteria now include assessment
of tissue exposure concentrations (TECs) for fish and shellfish harvesting and drinking water
exposure concentrations (DWECs) for drinking water. These changes to the state water quality
standards are not expected to impact stormwater management planning in Pasco until or unless
a local water body is included in the 303(d) list for TECs or DWECs or E. coli and a TMDL or
cleanup plan is developed.
Because the City relies heavily on underground injection controls (UICs) for stormwater
treatment, and there are a number of wells throughout Pasco, groundwater is another important
water resource. Groundwater resources are discussed further in the Critical Areas and Species
section of this document.
2.4. CRITICAL AREAS AND SPECIES
Critical areas are designated to protect natural resources and prevent harm to the community
from natural hazards. Natural resources typically refer to streams, wetlands, fish and wildlife
habitat conservation areas, and critical aquifer recharge areas (CARAs) and wellhead protection
areas (WHPAs). Generally, natural hazards refer to geologically hazardous areas (e.g., steep
slopes) and areas at risk for flooding. Specific definitions of critical areas criteria are documented
in Franklin County's 2009 Critical Areas Ordinance (Franklin County Code of Ordinances Title 18,
Chapter 3).
The critical areas ordinance protects wide-ranging resources for a variety of purposes. The
following sections describe the natural resources (groundwater, wetlands, and habitat) protected
by the ordinance and the natural hazard areas that have been identified in the city of Pasco to
protect the public from harm.
March 2023 (� HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 19
2.4.1. Groundwater Resources
Groundwater resources are an important consideration for stormwater planning efforts since
many stormwater management strategies that rely upon infiltration or underground injection
have the potential to influence groundwater quality. Although Pasco's domestic drinking water
is supplied by the Columbia River (Pasco 2014), there are 35 Group A or B wells, most of them
located in Basin 1 (Figure 2-6).
Group A wells are large systems that have at least 14 connections. Group B water systems are
smaller and have between 1 and 14 connections. Both Group A and B systems are regulated by
Washington State Department of Health and, as such, have designated wellhead protection
areas (WHPAs), which are shown on Figure 2-6. WHPAs are designated based on the estimated
time it would take a spilled contaminant to travel through the substrate and reach the drinking
water source. The majority of the WHPAs within Pasco are designated as "assigned," which
means that there is insufficient hydrologic data to accurately delineate travel -time boundaries.
There are two large WHPAs that contact the western and northern boundaries of Basin 1 that
are delineated based on a travel time of 10 years. Overall, 32 percent of the city lies within some
form of WHPA. The vast majority of the area within WHPAs lies within Basin 6, the newer, less
developed part of the city (Figure 2-6).
Similarly, a large portion of the city is designated as a Critical Aquifer Recharge Area (CARA). The
City of Pasco critical areas ordinance defines CARAs as areas within 100 feet of irrigation district
canals, or irrigated land that is designated as hydrologic soil group A. Because nearly all of the
city is designated hydrologic soil group A, virtually any irrigated land is considered a CARA.
CARAs are also mapped on Figure 2-6. (The wells, WHPA, and CARA data were collected as part
of the 2016 plan and were not updated as part of this effort since it is expected that no
substantive changes have occurred since that time.)
4 HERRERA March 2023
20 City of Pasco Comprehensive Stormwater Management Plan — 2023
,A
1
LQ coi
a0
'.-4 .
Legend Figure 2-6.
Wellhead Protection Area i Pasco City Limits Groundwater and Critical Areas Within
G months 1 Urban Growth Area boundary the City of Pasco.
1 year O Subbasin boundary
N
5 year Stream a
10 year Highway 0 4,500 9.000 18,000
Assigned Feet
River R� HERRERA
Wetland (NWI)
Aerml: E5R1 2020
K,�oe v+vzoznzaras.aoow:owa�o F,y:._w„empwa.", cw„a �Qm,uo aa. I>aZmn
2.4.2. Wetlands, Riparian Buffers, and Habitat
In total, there are approximately 172 acres of wetlands within the city limits. With the exception
of several small ponds scattered throughout the city, most of the wetland area is limited to the
southeast corner of Basin 6, on the peninsula that separates the Snake and Columbia Rivers. In
this area, there are approximately 80 acres of emergent wetland, and approximately 70 acres of
forested shrub wetland. All wetlands including freshwater lakes and ponds are shown on
Figure 2-6. (The wetland, lake, and pond data were collected as parf of the 2016 plan and were
not updated as part of this effort since it is unlikely to change.)
Pasco's shoreline master program includes 14.4 miles of the Columbia River. The reach has been
divided into 18 subreaches, each of which has its own environmental designation and respective
development standards, including standards for riparian buffers. Most of the river has a required
riparian buffer of 50 feet. Similarly, Pasco has 2.8 miles of frontage along the Snake River, which
is divided into two subreaches; one is designated as urban conservancy and the other high -
intensity industrial, with required riparian buffers of 75 and 50 feet, respectively.
The Columbia and Snake Rivers provide migratory and rearing habitat for Chinook, coho, and
sockeye salmon, bull and steelhead trout, Pacific and river lamprey, and white sturgeon. All of
these are priority fish species, and a few are listed as candidate species under the Endangered
Species Act (ESA). Both rivers also provide important waterfowl concentration areas and a known
occurrence of American white pelican, an endangered species. Within the upland portion of
Pasco are several mapped areas of burrowing owl occurrence, a candidate species for listing
under the ESA. There is also mapped shrub -steppe area, which is a priority habitat for
protection.
2.4.3. Geologic and Flood Hazard Areas
Natural hazards are defined in the City's critical areas ordinance. The most pertinent natural
hazards affecting stormwater planning and development potential are landslide hazard and
flooding. Landslide hazard areas are generally defined as areas with slopes greater than
15 percent. (A more complete definition of landslide hazard areas is described in the critical
areas ordinance.) Hillslope was calculated and mapped for the city using 2005 LiDAR data with a
pixel resolution of 6 feet (Figure 2-7). As shown in Figure 2-7, there are scattered, small areas in
Pasco where there may be some hillslope hazard based on LiDAR interpretation. Less than
1 percent of the city is mapped as having slopes greater than 15 percent (Table 2-4). Therefore,
hillslope hazard does not play a significant role in future development or stormwater planning.
(+L HERRERA
March 2023
22
City of Pasco Comprehensive Stormwater Management Plan — 2023
Table 2-4. Critical and Hazardous Areas Within Pasco by Basin.'
Basin
Wetlands
Acres
Percent
1
5.3
< 1
2
0.9
< 1
3
0.0
0
4
10.0
1
5
0.0
0
6
338
2
Total
518
2
Wellhead
Protection Areas
Acres I Percent
0
0
98
11
46
25
19
2
0
0
33
5,962
5,962
27
Hillslope Hazard
Area
(> 15 percent)
Acres
Percent
0.0
0
5.4
<1
0.0
0
6.3
<1
0.0
0
178
1
<1
190
FEMA Zone A/AE
(100-year flood)
Acres i Percent
45.0
4
91.3
11
16.0
9
40.3
4
5.2
2
1,166
7
1,408
6
FEMA Zone X500
(500-year flood)
Acres Percent
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
16
<1
16
<1
a Pasco basin boundaries include the urban growth area (UGA) boundary and unincorporated area within Franklin County.
Flood hazard areas were delineated based on the Federal Emergency Management Agency's
(FEMA) 100-year flood maps (Figure 2-7). More than 94 percent of the land area of the city is
area outside of the 500-year floodplain (Table 2-4). Virtually all of the remaining land area
(6 percent) is mapped as being within the 100-year floodplain (flood zone A), meaning that in
any given year this land has a 1 percent chance of flooding. Most of the area mapped area
within zone A is located along the margins of the Columbia and Snake Rivers and adjacent
wetlands. The FEMA maps also include part of the Esquatzel Coulee in the 100-year floodplain;
reportedly there may have been flash floods in the coulee many years ago, before transition of
this area to agricultural land. As described previously, the small amount of water that may
collect in the coulee goes underground well north of the airport and therefore well outside the
city limits. Only a very small portion of land (less than 1 percent) is listed as being in FEMA flood
Zone X500, which corresponds to areas within the 500-year floodplain. Therefore, there is little
concern for flooding in the city, this is especially true since both the Snake and Columbia Rivers
are controlled by dams. (The geologic and flood hazard assessment data were collected as part
of the 2016 plan and were not updated as part of this effort since it is unlikely to change.)
March 2023
City of Pasco Comprehensive Stormwater Management Plan — 2023
4t HERRERA
23
I
Legend
Figure 2-7.
Hillslope hazard >15%
Pasco City Limits
Flood and Steep Slope Hazards
slope
Urban Growth Area
Within the City of Pasco.
FEMA Flood Hazard Zones
boundary
Zone A/AE - High risk of
Subbasin boundary
N
flooding
River
V v
(100-year flood)
0 4,500 9.000 18,000
Stream
Feet
Zone X500 - Area of 500-
Street
year flood
H E R R E RA
Highway
Aerial ESRI 2020
K Y•waiit rv?t]14/611 tlif065,.1ev:.YN.sv WAdriF'rtv o .prfdl M.v
2.5. FUTURE CONDITIONS
2.5.1. Population Growth
Pasco's population was 69,000 in 2015 and is now over 78,000 as of 2021; this represents a
13 percent increase in population over a 5-year period. Together with the cities of Kennewick,
Richland, and West Richland, Pasco forms the "Quad -Cities" area of Eastern Washington. The
Quad -Cities are the fourth largest metro area in the state. It is an area that has been growing
fast; for example, the population in Pasco is expected to increase to 121,828 by year 2038 (Pasco
2018).
State growth projections estimate that Franklin County is expected to grow by approximately
21 percent (24,778 people) between 2020 and 2025 and will continue to add approximately
25,000 to 30,000 people every 5 years through the projected timeline of 2040 (OFM 2017). Since
Pasco is the only major city in Franklin County, it can be expected that the majority of the new
population will settle in Pasco.
2.5.2. Climate Change
The following information on climate change predictions was developed as part of the 2016
plan and was not updated as part of this effort since it is not expected to have changed
substantively.
Mountain snowpack is the most important influence on annual water supply for many
watersheds in the Northwest. The Columbia River drains from mountainous snowmelt dominant
watersheds and is characterized by a hydrograph where the peak runoff lags behind the peak
period of precipitation. This lag is because much of the cool season precipitation occurs as snow
and is stored until springtime temperatures rise above freezing, and there is significant snow
melt throughout spring and early summer. Therefore, snowpack supplies warm season (April
through September) streamflows that are important for migrating salmon and are heavily relied
upon by irrigators, hydropower producers, municipalities, and other users (Dalton et al. 2013).
Relatively recent climate change over the last century and anticipated future climate change
related to altered atmospheric conditions and warming temperatures continues to affect the
Northwest including the Columbia River and Columbia Plateau. For example, consistent with
global trends, annual mean temperature in the Pacific Northwest increased by approximately
0.68 to 0.88 degrees Celsius (°C) from 1901 to 2012 (Abatzoglou et al. 2014). Warming
temperatures have increased the freeze -free season or growing season by approximately
2 weeks over the last four decades (Abatzoglou et al. 2014). Indicators such as the length of the
freeze -free season, annual temperature extremes, and potential evapotranspiration during the
growing season are relevant linkages to climate impacts.
March 2023
* HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
25
Significant research on climate change predictions has been conducted by the Climate Impacts
Group (CIG) at the University of Washington. The group's research projects regional effects of
global climate change using a series of global climate models and two greenhouse gas
emissions scenarios. Two reports synthesize the most recent modeling results and associated
impacts for the Pacific Northwest including the Columbia Plateau region (Dalton et al. 2013;
Snover et al. 2013).
The research provides a basis for assessing impacts of climate change in the Columbia River
Basin by supplementing data with regional climate models and studies. For example, in the
Methow Valley, study results project July warming of 0.8°C (±1.9°C) to 2.8°C (±4.7°C) by 2080
(Caldwell et al. 2013). The warming rate for the Pacific Northwest over the next century is
projected to be in the range of 0.1 to 0.6°C per decade (ISAB 2007).
Significant consequences of a warming climate for snowmelt dominant watersheds, such as the
Columbia River Basin, are a reduction in snowpack and a substantial shift in precipitation
patterns, streamflow seasonality, and stream temperatures (Barnett et al. 2005; Dalton et al.
2013; Stewart et al. 2005; Elsner et al. 2010; Leppi et al. 2011; NMFS 2014). For example,
hydrologic models project that by mid-century, the peak runoff from snowmelt will occur
approximately 3 to 4 weeks earlier than the current average (Dalton et al. 2013). With an
extended growing season, warmer and dryer summers, and pressure to address runoff earlier in
the year, a number of hydrological and temperature related impacts can occur. Some general,
stormwater related predictions for the Columbia River Basin for the next 50 to 80 years include
the following (Dalton et al. 2013; Elsner et al. 2010; Hamlet et al. 2013):
• Changes in spring snowpack will result in a fundamental shift in the Columbia River Basin
climate from being dominated by snowmelt to being dominated by a mix of rain and
snow.
• Warmer temperatures leading to reduced snowpack will result in a transition from spring
to winter runoff, increased winter flow, and reduced late summer flow.
• Future occurrences of heavy rainfall are projected to be more frequent and more intense
and will exacerbate flooding in many areas, although this is most significant in basins
currently characterized as mixed rain and snow with current mid -winter temperatures
within a few degrees of freezing.
• There is a projected increase in water temperatures that could result in adverse impacts
on salmon, water quality, and human use of water resources.
• There is a projected increase in channel migration, landslide risk, erosion, and sediment
transport during wetter months, although these problems are not likely to be important
in Pasco.
• Seasonal, year to year, and decade to decade variations will remain an important feature
of local climates.
HERRERA
March 2023
26
City of Pasco Comprehensive Stormwater Management Plan — 2023
3. STORMWATER MANAGEMENT
FRAMEWORK
This section provides background information on the management framework for stormwater,
including a summary of the existing stormwater infrastructure and the key O&M activities
associated with the system, as well as information on the regulations that govern stormwater
management and a summary of related City municipal code and design standards. This section
also includes information on the City's stormwater utility and future conditions that may affect
stormwater management needs.
3.1. STORMWATER INFRASTRUCTURE AND OPERATIONS
AND MAINTENANCE
The City's stormwater infrastructure consists of a network of piped conveyances and infiltration
pipe. It includes over 50 miles of stormwater conveyance and more than 40 miles of infiltration
pipe, as well as other structures (e.g., catch basins, inlets, and manholes) (Table 3-1 and
Figure 3-1). (Table 3-1, Figure 3-1, and the accompanying text are based on the City's current
infrastructure mapping system, which is in the process of being updated. However, it is expected
that the data presented still provides an appropriate overview of the types and amount of
stormwater infrastructure that the City manages.)
Table 3-1. Stormwater Infrastructure Within Pasco by Basin.a
Basin Catch Basins
Inlets
Manholes
Infiltration Pipes
(feet)
Conveyance
Piping (feet)
Outfall
Location
1
152
381
108
11,875
29,993
Columbia River
2
80
383
106
7,383
42,858
Columbia River
3
15
67
34
1,468
10,962
USACE Drainage Ditch
4
47
489
172
3,025
75,836
Fish Pond
5
15
113
55
755
19,163
USACE Drainage Ditch
6
2,459
4,814
360
210,882
108,577
All Discharge Via UIC
Total
2,768 6,247
835
235,389
287,389
a Pasco basin boundaries include the urban growth area (UGA) boundary and unincorporated area within Franklin County
USACE = United States Army Corps of Engineers
UIC = Underground Injection Control
March 2023
'tJ HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 27
Tr
Y
Yc9/r,
4> F
t F
r�
�2ao
el
39$
ts�
Legend Figure 3-1.
Pasco City Limits Inlet Stormwater Infrastructure
Urban Growth Area boundary Manhole in the City of Pasco.
IO Subbasin boundary Main conveyance N
t'S_i River Infiltration pipe a
Stream Street 0 4,500 9,000 18,000
Highway IIIM Feet
HERRERA
Aerial: ESRI 2020
As described previously, the stormwater system in the city is defined by six basins (Figure 3-1).
Basins 1 through 5, which represent the older parts of the city, are serviced by a conventional
conveyance network that carries stormwater to outfalls that discharge to surface water; two of
these outfalls discharge directly to the Columbia River. Due to the flat topography, this system is
often deeply buried; the conveyance system in much of the city is over 20 feet below ground
surface. In Basin 6, which represents the majority of the city, stormwater is conveyed into the
ground via dry wells and infiltration systems (UICs). In these areas, catch basins are connected
directly to infiltration pipe. In a few areas, short 'mains' collect water from a small number of
catch basins and transport it to an infiltration pipe.
The key O&M activities associated with upkeep of the stormwater infrastructure and reducing
pollutants generated by stormwater include inspections, street sweeping, catch basin cleaning,
and vegetation management. All catch basins are inspected at least once every year and
vactored when necessary.
As described in the 2016 plan, street sweeping used to involve sweeping of arterials weekly and
sweeping of residential streets every 1 to 2 months. Due to lack of staffing, street sweeping
frequency has decreased to monthly sweeping of arterials and quarterly sweeping of residential
streets. This staffing issue has also impacted the frequency that the City is able to dedicate to
closed-circuit television (CCTV) inspections. More information on how street sweeping is
impacting existing infiltration facilities can be found in Section 4.2.1 and O&M staffing
recommendations can be found in Sections 5.6 and 6.2.
3.2.APPLICABLE REGULATIONS
While the NPDES permit, which is discussed at length in this plan, is the primary regulation that
affects the City's stormwater management program, a number of other local, state, and federal
regulations must also be considered. Table 3-2 provides a brief summary of the most relevant
regulations.
Table 3-2. Summary of Applicable Regulations.
Issuance
Effective
Expiration
Name of Regulation
Date
Date
Date
Description
July 2019
_
Aug. 1,
July 31,
Eastern Washington
Contains in-depth requirements for the City's
NPDES Phase II Permit
2019
2024
SWMP that are discussed in detail in the gap
analysis and in this plan. The permit is reissued
on an approximately 5-year cycle.
State surface water
Jan. 23,
Feb. 23,
NA
The City needs to manage discharges from
quality standards
2019
2019
stormwater systems in a manner that supports
(WAC 173-201A)
achieving surface water quality standards. A new
rule has been released that updates surface
water quality standards to include human health
criteria. The final rule was adopted in 2016 and
new water contact recreation bacteria criteria
(E. coli for fresh water) was adopted in 2019.
March 2023 4 HERRERA
City of Pasco Comprehensive Stormwater Management Plan - 2023 29
Table 3-2 (continued).
Name of Regulation
Groundwater quality
standards
(WAC 173-200)
303(d) list
Model Toxics Control
Act
(WAC 173-340)
Safe Drinking Water Act
Underground Injection
Control (UIC)
(WAC 173-218)
National Flood
Insurance Program
(NFIP)
Shoreline Management
Act
(RCW 90.58)
Growth Management
Act
(RCW 36.70A)
Endangered Species Act
(ESA)
* HERREM
of Applicable Regulations.
Issuance
Effective
Expiration
Date
Date
Date
Description
Oct. 31,
Dec. 1,
NA
The City needs to manage discharges from
1990
1990
stormwater systems in a manner that supports
achieving groundwater quality standards.
2016
NA
July 22,
This is the water quality assessment of all State
2016
waters in terms of whether they meet water
quality standards. Those that do not meet water
quality standards (e.g., impaired waters) must
have plans for their cleanup. Several
impairments are listed for the Columbia River,
but none are currently adjacent to or directly
downstream of any City of Pasco stormwater
outfalls.
1988
NA
1988
Governs the cleanup of contaminated sites in
(most
the state of Washington; also provides a
recently
funding source for municipal stormwater
amended
programs.
in 2019)
Requires actions to protect drinking water and
1974
1974
NA
(most
its sources, including groundwater wells.
recently
Administered by the Washington State
amended
Department of Health.
in 1996)
1984
1984
NA
Defines how new (constructed after Feb. 3,
(most
2006) UIC wells must be constructed. Requires a
recently
well assessment for existing UIC wells. Existing
amended
UIC wells that are determined to be a high
in 2008)
threat to groundwater must be retrofitted.
May 10,
May 10,
NA
This program aims to reduce impacts of
1977
1977
flooding by encouraging communities to adopt
floodplain management regulations through
insurance provisions. The City participates in the
NFIP, which is administered by FEMA.
1971
1972
NA Requires that the City develop a plan for
managing and protecting significant shorelines.
The City has updated its Shoreline Master
Program and it was adopted in 2016.
1990
1990
NA Requires the City to inventory and protect
(most
environmentally critical areas, and to develop
recently
comprehensive plans to ensure environmentally
amended
responsible and economically sustainable
in 2022)
development and implementation of CIP
pro'e� cts.
1973
1973
NA Provides for the conservation of species that are
(most
endangered or threatened and their habitat. The
recently
City's stormwater system operations and private
amended
development stormwater management activities
in 2020)
that are permitted by the City may be affected.
March 2023
30 City of Pasco Comprehensive Stormwater Management Plan — 2023
Name of
Table 3-2 (continued). Summary of Applicable Regulations.
Issuance Effective Expiration
Date Date Date
Salmon Recovery 1998
Planning Act (most
(RCW 77.85) recently
amended
in 2009)
Watershed Planning Act
(RCW 90.82)
State Environmental
Policy Act (SEPA)
(RCW 43.21 C)
Pasco Municipal Code
(PMC)
NA = not applicable
1998
(most
recently
amended
in 2014)
1971
(most
recently
amended
in 2020)
Various
1999 NA This act (in association with ESA) requires that
recovery plans be developed for listed salmon
species. The associated Salmon Recovery
Funding Act provides funding for habitat
protection and restoration projects and
associated activities to benefit salmon.
1998 NA Provides a framework for local solutions to
watershed issues and implementation of locally
based solutions.
1971 1 NA
Various i NA
Requires identification of possible
environmental impacts that may result from
governmental decisions to issue permits for
private projects; construction of public facilities;
or adoption of regulations, policies, or plans.
Several sections of the PMC govern aspects of
stormwater management including, but not
limited to:
• Title 3: Revenue and Finances (fees for code
enforcement violations, stormwater
construction permit fee, and stormwater
utility rates)
• Chapter 13.80: Stormwater Management
Utility
• Section 14.10.030: Inspection of Public
Works Construction
• Section 16.10.050: Drainage Requirements
(building and construction code)
• Section 23.35.060: SEPA Policies
• Section 25.175.060: Site Drainage
(zoning code)
• Section 21.35.040: Drainage Plans
(subdivision code)
3.3. MUNICIPAL CODE AND DESIGN STANDARDS
Typically, guidance for design of stormwater facilities is provided through a city's municipal
code, a stormwater design manual or design guidelines handbook, and a city -specific set of
standard details or specifications. The City has adopted the Stormwater Management Manual
for Eastern Washington (SWMMEW), but it may also be necessary to revise the Pasco Municipal
Code (PMC) language to include additional thresholds related to sizing or locating stormwater
March 2023
* HERRERA
City of Pasco Comprehensive Stormwater Management Plan - 2023
31
facilities. Standards currently present in the PMC or in City standard details related to
stormwater design include:
• PMC 13.80.100 Storm Water Construction Permit Required. "A storm water site plan is
required for any project subject to Core Elements Nos. 2, 3, 4, 5, 6 or 8 per Chapter 2 of
the SWMMEW. Upon approval of the storm water site plan, a storm water construction
permit shall be issued upon payment of the storm water construction permit fee as
provided in the City fee summary ordinance, Chapter 3.35 PMC."
• PMC 16.10.050 Drainage requirements. "An impervious surface improvement shall be
designed to drain, confine and/or impound storm water or site -generated water within
the private property upon which the improvement is to be located. The Building
Inspector shall determine the adequacy of all plans and methods for the drainage or
proposed impervious surface improvements in conjunction with the most current
adopted Stormwater Management Manual for Eastern Washington."
• PMC 25.175.060 Site Drainage. "All storm drainage shall be retained on site and
controlled by way of drainage swales, dry -wells, French drains or other means as
approved by the City Engineer."
• PMC 21.35.040 Drainage Plans. "Drainage and site grading plans shall be prepared in
conformance with the standard drawings and materials lists and shall be prepared by a
professional civil engineer registered in the State of Washington."
• Chapter 7 of the City's Design and Construction Standards covers stormwater
improvements, including the following:
o Design criteria
o Design storms
o Hydrologic analysis
o Treatment best management practice (BMP) sizing
o Flow control
Section 5 contains recommendations for the municipal code to address some of the deficiencies
in the existing code and guidance.
4 HERRERA
March 2023
32 City of Pasco Comprehensive Stormwater Management Plan — 2023
3.4. STORMWATER UTILITY FUND
Creating a storm and surface water utility and imposing service charges is authorized by
RCW Chapter 35.67. Pursuant to that statute, the City of Pasco enacted Chapter 3.07.190 of the
PMC to implement a stormwater utility charge. This charge is necessary to fund SWMP activities
and projects that are required to provide services to residents, support development, and meet
regulatory requirements. The remainder of this section describes the history, purpose, and uses
of the City's stormwater utility fund.
3.4.1. History and Purpose
The City of Pasco first created the Stormwater Utility Fund and set initial stormwater utility rates
in May 2002 by the passage of Ordinance No. 3543. The rate structure has remained the same
since establishment and includes two different classes of property:
! Single-family and multi -family residential parcels:
o Flat rate (multi -family and apartments are charged a per unit rate) because these
types of sites are similar in terms of lot size and impervious area coverage
throughout the city. Thus, they generate a similar amount of runoff and pollution,
which incurs a similar cost per parcel/unit for services provided.
o Parcels with vacant buildings are charged the same rate as parcels with occupied
buildings.
o Undeveloped parcels are not charged a monthly rate.
• Commercial and industrial parcels:
o Sliding rate that is based on the total number of parking spaces.
o Additional rate based on acreage if the parcel discharges to the City's stormwater
system.
o State highway right-of-way owned by the Washington Department of Transportation
is charged a per -acre rate that is 25 percent of the per -acre rate for commercial
parcels.
In 2002, single-family residential homeowners paid a flat rate of $1.80 per month per parcel,
while industrial and commercial businesses paid a rate based on the number of parking spaces
($1.80 to $9.00 per month) plus an additional charge of $30 per acre if their stormwater
discharges to the City's stormwater system. Table 3-3 summarizes the stormwater utility rates
since 2002.
March 2023
4 HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
33
Table 3-3. City of Pasco Stormwater Utility Monthly Rates from 2002 to Present.
Ordinance
No.
Ordinance Information
SFR and
Vacant
Building
$1.80
Monthly
Charges
Adoption Date
May 6, 2002
Effective Date
May 11, 2002
Multi -Family
Residential
and
Apartments
$0.90/unit
Commercial and Industrial
$1.80—$9.00' plus $30/acreb
$3.00—$15.00a plus $66.70/acreb
$3.90—$19.50a plus $86.71/acreb
3543
4000
March 21, 2011
April 1, 2011
$3.00
$1.50/unit
4039
January 17, 2012
February 1, 2012
$3.90
$1.95/unit
4139
January 21, 2014
February 1, 2014
SFR—$4.40
Vacant—
$5.52
$2.20/unit
$4.40—$22.0011 plus $86.71/acreb
4142
February 3, 2014
February 1, 2014
$4.40
$2.20/unit
$4.40—$22.001 plus $86.71/acreb
4212
March 2, 2015
April 1, 2015
$4.90
$2.45/unit
$4.90—$24.501 plus $96.66/acreb
4369`
December 4, 2017
January 1, 2018
$5.64
$2.82/unit
$5.64—$28.18a plus $111.16/acreb
January 1, 2019
$5.92
$2.96/unit
$5.92—$29.58a plus $116.72/acreb
January 1, 2020
$6.21
$3.11/unit
$6.21—$31.06a plus $122.55/acreb
January 1, 2021
$6.52
$3.26/unit
$6.52—$32.62a plus $128.68/acreb
January 1, 2022
$6.85
$3.42/unit
$6.85—$34.251 plus $135.11/acreb
January 1, 2023
$6.85
$3.42/unit
$6.85—$34.25a plus $135.11/acreb
a Sliding scale based on number of parking spaces (0-5, 6-10, 11-15, and 16+ vehicles)
b Property runoff to City's stormwater system ($0.90 per acre minimum in 2002, $1.39 per acre minimum in 2022). State highway
right-of-way (WSDOT) is charged a per acre rate that is 25 percent of the commercial/industrial rate ($0.30 per acre minimum in
2002, $0.84 per acre minimum in 2022).
Based on a rate study with the assistance of FCS Group in September 2017.
SFR = single-family residential
In January 2007 (effective February 2007), Ecology issued the NPDES permit to the City and
27 other jurisdictions (19 cities and 8 counties) in Eastern Washington. Ecology reissued the
Phase II Municipal Stormwater Permit for Eastern Washington with updated permit requirements
in August 2014 and August 2019. The NPDES permit outlines SWMP activities and
implementation milestones that the City must follow in order to comply with federal law. All
Phase II communities are expected to develop a SWMP that includes all the required activities,
to implement those activities within the required time periods over the permit term, and to
submit annual reports to Ecology to document progress toward complete permit compliance
and program implementation. A detailed description of the major elements of NPDES permit
compliance, most of which require funding from the stormwater utility, is described in Section 5.
As is typical of most of the cities that are regulated by the NPDES permit, Pasco's stormwater
utility rates have been increasing as a response to the regulations and required expansion of the
program. The rates were initially at $1.80 per single-family residence in 2002 and are now at
$6.85 per parcel (Table 3-3). Similar increases have occurred for industrial and commercial
businesses.
March 2023
City of Pasco Comprehensive Stormwater Management Plan - 2023
3.4.2. Past and Current Use of Funds
Based on the revenue reported in 2011, it can be assumed that in the early years of NPDES
permit implementation (2007 to 2011), the utility generated about $55,000 per year, yet
expenses ranged from $105,000 to $330,000. Thus, the majority of the costs for running the
program were covered by the City's general fund. From 2012 to 2018, the utility has generated
approximately $80,000 to $130,000 per year, but expenses have continued to be well above that,
ranging from $100,000 to $400,000. While stormwater permit compliance has accounted for a
healthy share of the fund as the City has developed its program, the majority of the stormwater
budget was spent on O&M activities and stormwater system improvements.
3.4.3. Population Growth
The city has experienced rapid growth over the past 15 years, more than doubling its population
from 32,066 in 2000 to over 78,000 as of 2021. Population growth and expanded service areas
equate to an expanded city road network, resulting in a greater demand for catch basin cleaning
and street sweeping, which are key O&M activities supported by the stormwater utility.
Although population growth will bring proportional increases in impervious surfaces and
pollutants, all new development and redevelopment will need to meet City standards and,
therefore, rely on infiltration for control of stormwater. Although impacts from development
cannot be entirely eliminated, the new growth is not expected to substantively; exacerbate
flooding or increase discharge of pollutants to nearby surface waters.
In the sense that the large increase in infiltration facilities proportionately increases the risk of
pollutants entering groundwater, groundwater resources could be at greater risk. Expanded
programs for educating the public and businesses about source control and required or
improved stormwater treatment in commercial and industrial areas would help to mitigate those
risks. Since stormwater utility fees will be applied to new development, the additional program
needs should be largely covered by the increased revenue generated.
3.4.4. Annexation
Annexation of new area is another mechanism that increases the City's stormwater management
obligations, although it also comes with increased revenue from utility fees. The City has
annexed more than 400 acres since the 2016 plan was prepared, and the City anticipates more
of the UGA may be annexed in the future.
3.4.5. Climate Change
As described in Section 2, there are some significant climate change predictions for the Pasco
area. However, due to the dams on the Columbia River, changes in river flows and flooding will
be controlled at a regional level; management of stormwater at the city level should not be
March 2023
4 HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 35
impacted. However, predicted climate change impacts in the area may intensify the need for
stormwater management practices that promote storage and preserve water quality. Water
storage, infiltration of stormwater, groundwater recharge, and stormwater treatment will
become increasingly important as population grows, and seasonal water supply is altered by
climate change.
A number of steps can be taken as part of stormwater management planning to mitigate for
some of these impacts. They include:
• Continuing to promote onsite infiltration to control 100 percent of stormwater runoff on
all sites where it is feasible.
• Promoting stormwater storage where feasible.
• Modifying conveyance and treatment sizing requirements for new and redevelopment to
account for larger peak flow events.
• Considering retrofitting existing infiltration devices with improved water quality
treatment, especially in commercial or industrial areas.
{h,t HERRERA
March 2023
36 City of Pasco Comprehensive Stormwater Management Plan — 2023
4. STORMWATER SYSTEM PROBLEMS,
PRIORITIZATION, SOLUTIONS, AND
IMPLEMENTATION
4.1. PROBLEM IDENTIFICATION AND PRIORITIZATION
Stormwater system problems were identified, evaluated in the field, and prioritized using a
custom set of criteria. This section describes the process used to prioritize projects. Stormwater
system problems are described, in general, in Section 4.2 and solutions are summarized in
Section 4.3.
Stormwater system problems and projects were identified from two sources: past projects from
the 2016 CIP projects list, and all problems identified through a survey of City staff ("staff
survey") completed in January 2022. The staff survey collected information on known current
stormwater problem locations. Together, the 2016 CIP project list and the staff survey problem
location list resulted in a total of 44 potential problem or project sites. Of these 44 sites, 8 were
removed because they were either complete or in progress (5 sites) or duplicates (3 sites).
Table 4-1 lists and categorizes the 36 remaining sites. City staff selected 24 of these 36 problem
sites to retain for capital project prioritization and solution development. These 24 sites were
then evaluated in the field by two Herrera engineers, accompanied by City staff, on March 11,
2022.
Table 4-1.
Category
rization of Site -Specific Problems.
Problem Names
Tier 1 - High Priority (included in 2022 CIP) S Oregon Avenue North of E Ainsworth Street'
127 S Hugo Avenue 214/219 N Sycamore Avenue
Tier 2 - Medium Priority
March 2023
W Sylvester Pipe Repair`
127 S Hugo Avenue
1801 N Commercial Avenue
6415 Burden Boulevard
600 East A Street
4416 Sedona Drive
E Helena Street Stormwater Improvements:
• E Helena Street at S Beech Avenue
• E Helena Street at S Owen Avenue
• E Helena Street at S Elm Avenue
• 511 S Hugo Avenue
i<o 631 S Hugo Avenue
* HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
37
Table 4-1 (continued). Categorization of Site -Specific Problems.
Category
Tier 2 — Medium Priority (continued)
Problem Names
E Highland Street from N Elm Avenue to N Cedar Avenue
6021/6013 W Melville
604 N Cedar Avenue
8716 Kingsbury Drive
W Court Street Stormwater Retrofit
First Avenue Pipe Rehabilitation
Volunteer Park Pipe Relining
Sylvester North Pipe Relining
Annual Pipe Rehabilitation
Tier 3 -- Low Priority
City to Design, Construct, and/or Maintain
2714 Fleming Lane
3609 Riverhaven Street
1330 E Broadway Street
804 Road 35
1303 W Shoshone
533 S Owen Avenue
S Wehe Avenue at E Alton Street
Developer Responsibility
Private Property
Water Quality (from 2016 plan)
S 20th Avenue and W A Street
S Oregon Conveyance Improvements
Residential Pilot Bioretention Retrofit —Effectiveness Study Project
Commercial Pilot Infiltration Retrofit —Effectiveness Study Project
Infiltration Systems (Boat Basin Retrofit)
Boat Basin Water Quality BMP
Industrial Basin Water Quality BMP
a City to design in-house to correspond with the 2023 road overlay project.
b Corresponds to N Sycamore Ave Infiltration Improvements identified in the 2016 plan.
Corresponds to Sylvester South Pipe Repair identified in the 2016 plan.
A prioritization system (Figure 4-1) was developed to evaluate and rank the 24 problem sites for
potential CIP projects. These were divided into two categories: flooding infrastructure and
deteriorated infrastructure. All 24 problem sites were evaluated for risk, project efficiency,
maintenance level of effort, and mobility benefit. The risk definitions and other criteria are
described in subsections 4.1.1 through 4.1.3. Figure 4-1 (a) shows a diagram of the prioritization
process and Figure 4-1 (b) defines the prioritization criteria by project category (i.e., illustrates
criteria used for flooding infrastructure projects relative to those used for deteriorated
infrastructure projects). Figure 4-1 (c) compares this prioritization process to the process used by
the 2016 plan.
(b HERRERA
March 2023
38 City of Pasco Comprehensive Stormwater Management Plan — 2023
u
a
L O C
4-0 � ' Q O
u +�
rC
L � L
a m
O L t —
.� • . O O N
a W +�+ = .:
0 .3 - a
0 y m
o � �
V
O fa 4-6
1 � i
L V
i
'a i • a 4a
O � .tZ
LL. L LU O
u
� a
O
L
a
o c
O
ai O 4-+ },
• u
• ++ CL 0 ++
i-+
GJ f1 O 0 i
O u Ll. i 0
L 'L
A
� � L
�y ^' • +O+ O O
4-1
O .0 LA d 0 in O tin L
rx
CL - ❑ c a
R.
Y
N
(n
L
Q�
:
c
Qi
O
u Q
�+
4-
O
N,
O
f�0
N O
=
CO
'
O
O
O
m
00
V
N
�
L
�
Q�
L
O
v
�
Q
4-j
C
M
W
(V
O
421H
wnipaW
mol
w
ce
lz
LU
tiA
c
�
�
OA
Q
tv
W
OE
N
L..
O
�
�
� x
p
41
U
U
W
c .,�,,,2
O
� �
OL O
Q. �
Q �
v �O
'p
N
G1
"O
N N
t
w
—
4A —
i
N O
O N
O
_c u
•7 �
E
OA
.N
�
V
a-+
N c
p L
"6 N
a� E
O c L
.� a,
E N
cu
}J
c
Y
L
N
,}
•
�-^ c�
f0 N
4-J -c
y. 4•
O1
E
O
3
N �
v
c
O ++
v>
L O0
E '� o
O E
t
3
a�
+'
N N
L L
m a
fO E
CA
+' Q
N
—>
�
L
> c
-a
N
t o
+�
v
" E
3 c=
4n�
c
v
E
O
Ln U
�
N '�
O
Y
N
� 5
Cr
N
N
Q. =
O
O
N
L
w
Q W
Z
0
cn
-
'i
cc
O
V
O
t�
O
nOi
N
O
N
CL
U
}'
4-J
u O
O
a
c�
J
N
CO
to
c
V
•
Y
Ln
Lu
c44-
� O
p
a
OC
m;
4
LL
0
J
ccp
G
w
'O
•
d
•V
N
•
D_
O
L
Vq
ii
N
The prioritization system was applied to rank the 24 sites. Sixteen sites were ranked as "medium"
or "high," and were presented to City staff for input. Of these 16 top -ranked sites, 8 were
classified as Tier 1 sites and included in the current plan cycle. Project solutions were developed
for each of these sites for the City to include in their current CIP list. Sites that were not selected
for this current plan cycle are classified as Tier 2 if they ranked "medium" or "medium -high" in
priority, or Tier 3 if they ranked "low" in priority. Table 4-1 includes Tier 1, 2, and 3 sites as well
as the following problems:
• Problem sites designated for the City to maintain or construct,
e Problem sites designated as the responsibility of the developer,
• Problems found to be on private property, and
• Water quality projects from the 2016 plan.
Projects from the 2016 plan that have been completed are not included in this plan. Projects
that were carried over from the 2016 plan into the current plan are noted in the footnotes
section of Table 4-1.
4A.1. Risk Definition - Flooding Infrastructure
Risk was defined for flooding infrastructure based on three criteria: frequency, severity, and
traffic level. Frequency was defined as "high" if flooding occurred after every rain event,
"medium" if flooding occurred several times per year, and "low" if flooding occurred one or
fewer times per year. Severity was defined as "high" if flooding occurred in the travel lane,
crosswalks or curb ramps, or privately owned structures such as garages, "medium" if flooding
occurred only on private property but did not impact structures, and "low" if flooding only
impacted the edge of the roadway. Traffic level was defined as "high" if the average daily traffic
(ADT) count was greater than 5,000, "medium" if the ADT was between "no count data" and
5,000, and "low" if the ADT had no count data. The ADT was assessed using the Existing All Day
Traffic Counts figure from the current Pasco Comprehensive Plan (Pasco 2020). Figure 4-1 (b)
shows a tabulated version of these definitions.
4.1.2. Risk Definition - Deteriorating Infrastructure
Risk was defined for deteriorating infrastructure based on three criteria: pipe size, pipe defects,
and traffic level. Pipe size was defined as "high" if the diameter was greater than 12 inches,
"medium" if the pipe diameter was between 8 and 12 inches, and "low" if the pipe diameter was
less than 8 inches. Pipe defects were defined as "high" if there were pipe failure or major holes,
"medium" if there were bellies, fractures, or offset joints, and "low" if there were only root
intrusions and related holes. Traffic level was defined using the same methods developed in
Section 4.1.1. Figure 4-1 (b) shows a tabulated version of these definitions.
* HERRERA
March 2023
42 City of Pasco Comprehensive Stormwater Management Plan — 2023
4.1.3. Other Criteria
Other criteria used to prioritize the problem sites include project efficiency, maintenance level of
effort, and mobility benefit. Project efficiency reflects whether stormwater improvements at the
problem site can occur with another project or not. Maintenance level of effort reflects problem
sites that require more than typical effort to maintain: "high" is defined as projects requiring
three Vactor truck loads per maintenance call or comparable effort for pipe maintenance,
"medium" is defined as projects requiring two Vactor truck loads per maintenance call or
comparable effort for pipe maintenance, and "typical" or "low" is defined as projects requiring
one Vactor truck load per maintenance call or comparable effort for pipe maintenance. Mobility
benefit is defined as whether stormwater improvements can be made in conjunction with
adding accessibility improvements (e.g., curb ramps) where they are missing. Figure 4-1 (b)
shows a schematic version of these criteria.
4.2. PROBLEMS
The primary stormwater issues faced by the City include flooding, deteriorating conveyance
infrastructure, and lack of water quality treatment prior to discharge to the Columbia River.
4.2.1. Flooding
Problem flooding occurs due to:
• Undersized facilities (given their contributing drainage area),
• Clogged facilities (likely due to regular transport of sediments),
• Poorly located facilities (i.e., not in the area's low spot), and
• Absent facilities.
The following is a list of Tier 1 flooding projects that were identified during this planning process
and are a result of undersized, poorly located, absent, and/or clogged facilities:
• South Oregon Avenue North of East Ainsworth Street: The existing stormwater
facilities are not located in the road's low spot. South Oregon Avenue is coincident with
SR 397, and the roadway is subject to moderate traffic. The roadway may have settled
since the installation of the stormwater system. The southbound travel lane floods during
rain events, presenting a hazard to relatively high-speed traffic.
• 214/219 North Sycamore Avenue (this corresponds to North Sycamore Avenue
Infiltration Improvements in the 2016 plan): The existing stormwater system is
undersized for the drainage area and/or has become clogged. Portions of the roadway
flood with over 1 foot of standing water (i.e., up to adjacent lawns) several times per
year. Multiple Vactor truck loads are needed to mitigate flooding during most rain
events.
March 2023
46 HERRERA
City of Pasco Comprehensive Stormwater Management Plan -- 2023
43
• 127 South Hugo Street: The existing stormwater system is undersized for the drainage
area and/or has become clogged. A commercial driveway contributes to the drainage
area. The roadway floods during rain events and water drains down adjacent driveways
into private garages multiple times per year.
« 1801 North Commercial Avenue: The existing stormwater system is undersized for the
drainage area and/or has become clogged. The travel lanes flood during rain events,
presenting a hazard to moderate traffic in this industrial area, which is frequented by
heavy trucks.
6415 Burden Boulevard: The existing stormwater system is undersized for the drainage
area and/or has become clogged. The intersection with Robert Wayne Drive floods,
impeding the travel lane, sidewalk, and a commercial driveway, and presenting a hazard
to pedestrians and vehicles in this area with heavy traffic.
« 600 East A Street: This low spot in the road lacks stormwater infrastructure. Roadside
parking and an intersection flood during rain events, impeding travel lanes, parking, and
pedestrian routes, and presenting a hazard to pedestrians and vehicles in this moderate
traffic area.
• 4416 Sedona Drive: The existing stormwater system is undersized for the drainage area
and/or has become clogged. Both travel lanes flood during large rain events, and water
flows into an adjacent driveway and a private garage on this residential street.
4.2.2. Deteriorating Conveyance Infrastructure
As described in Section 3, five of the six stormwater basins within Pasco are served by a
traditional conveyance network of catch basins and buried pipes that collect stormwater and
convey it to outfalls to the Columbia River or ditches owned by the Army Corps of Engineers.
This infrastructure is on average approximately 65 years old, and therefore inspection, repair,
and maintenance of the structures is an important long-term need. In 2014, the City undertook
an effort to clean and inspect the storm system within Basin 2. Storm lines were jetted and
inspected, using closed-circuit television (CCTV), to assess condition and identify illicit
connections.
Based on these inspections, it is a reasonable assumption that much of the existing stormwater
system in the five basins served by a buried conveyance system need additional inspection and
rehabilitation to extend the system's useful life by addressing system damage such as holes,
offset joints, fractures, bellies, root intrusion (and related holes), and erosion. In addition to
physical pipe damage, accumulated debris and root penetrations were also encountered, even
after the pipes were jet cleaned. In some cases, these maintenance issues resulted in major
obstructions.
March 2023
City of Pasco Comprehensive Stormwater Management Plan — 2023
Multiple deteriorating pipe projects were identified during development of the 2016 plan, and
an annual repair program for failing pipes was recommended. While individually these projects
were classified as Tier 2 (Table 4-1), a pipe relining program has been included in the CIP
budget:
• Stormwater Pipe Relining (Phases 1 and 2): See Table 4-4 in Section 4.3 for details.
One Tier 1 deteriorating infrastructure CIP project was identified for rehabilitation during the
development of this plan:
• West Sylvester Pipe Repair (this corresponds to the Sylvester South Pipe Repair
project from the 2016 plan): Existing pipes contain holes, fractures, and heavy root and
debris intrusions. This project will require replacement or repair three sections of aging
and damaged pipes along and tributary to West Sylvester Street.
A second Tier 1 deteriorating infrastructure CIP project was identified by the City as this plan
was being finalized:
• Schlagel Park Stormwater Main Replacement: Project details will be developed by the
City at a later date.
4.2.3. Lack of Water Quality Treatment
Although stormwater in the majority of the city (all of Basin 6) is infiltrated, Basins 1 through 5
are still served by piped conveyance systems to five outfalls that directly or indirectly discharge
to the Columbia River without treatment.
The NPDES permit requires the City to implement water quality treatment requirements for new
and redevelopment projects consistent with Appendix 1 of the permit. Since the Columbia River
is a flow -control -exempt surface water, these basins will not require flow control facilities unless
flow control is required by City code.
The 2016 plan proposed five water quality projects. They are described in Section 4.1.3 of the
2016 plan and listed in Table 4-1. These projects have yet to be implemented and therefore
have been retained for inclusion in the long-term CIP list. No modifications have been made to
the 2016 project solutions during this planning effort, and no new water quality focused projects
have been identified during development of this plan.
4.2.3.1. Stormwater Code Violations
According to the 2022 NPDES annual report, a total of 12 stormwater code violations, including
illicit discharges, were identified in the 2021 reporting period (Table 4-2). All 12 of the code
violations were eliminated (Pasco 2022). The City has no known chronic non-stormwater
discharges or illicit connections to the MS4 (Pasco 2022).
March 2023
* HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
45
Table 4-2. Stormwater Code Violations.
Number
Number of
of
Corrected
Code Section
Topic
Violations
Violations
PMC 10.65.020 (1)
Allowing oil or grease to be dropped from a vehicle
4
4
PMC 13.70.030
Deposit of refuse on the ground
6
6
PMC 13.80.110
1 Prohibited discharges
2
1 2
4.3. SOLUTIONS
Site -specific problems and proposed CIP solutions for all Tier 1 projects are identified in
Table 4-3. Figure 4-2 provides a map of the problem and solution locations. Summary sheets
and cost estimates developed for seven of the Tier 1 2022 CIP projects are provided in
Appendix C. Most problems addressed by this plan are flooding issues caused by inadequately
sized, poorly located, and/or clogged infiltration facilities, or failing and/or reduced performance
of aging conveyance system components. Projects from the 2016 plan that reduce water quality
impacts and risks are listed in Table 4-1, but none were identified as Tier 1 projects for
implementation. As described in Section 4.2, independent of this plan development effort, the
City identified one additional project, Schlagel Park Stormwater Main Replacement, for inclusion
as a Tier 1 project.
Name
S Oregon Avenue
North of
E Ainsworth Streeta
214/219 N Sycamore
Avenueb
Table 4 3. Tier 1 Problems and CIP Solutions.
Problem
• Flooding: The existing stormwater
facilities are not located in the road's
low spot. South Oregon Avenue is
coincident with SR 397. The travel lane
floods during rain events, presenting a
hazard to relatively high-speed traffic.
• Flooding: The existing facilities are
undersized and/or clogged. Travel
lanes and adjacent lawns flood several
times per year. Multiple Vactor truck
loads are needed to mitigate flooding
during most rain events.
127 S Hugo Avenue • Flooding: The existing facilities are
undersized and/or clogged. Water
floods into the travel lane and a private
garage several times per year.
4 HERRERA
Solution
• Stormwater improvements will be
designed by City staff to coincide with
a 2023 road overlay project.
• Install the design equivalent of
thirty-one (31) Type 11 catch basins,
each connected to a 20-linear-foot
infiltration trench, within this drainage
area to manage the contributing
stormwater runoff. (This project is
included as part of the Infiltration
Improvements Program for purposes
of capital budget planning.)
• Install the design equivalent of eight (8)
Type II catch basins, each connected to
a 20-linear-foot infiltration trench,
within this drainage area to manage
the contributing stormwater runoff.
(This project is included as part of the
Infiltration Improvements Program for
Durposes of capital budget Dlannina.)
March 2023
46
City of Pasco Comprehensive Stormwater Management Plan - 2023
Project Name
W Sylvester
Pipe Repair
(This is also referred
to as Sylvester Pipe
Repair - 5th Ave to
10th Ave)
1801 N Commercial
Avenue (This is also
referred to as
1801 N Commercial
Avenue Pond
Retrofit)
6415 Burden
Boulevard
Table 4-3 (continued). Tier 1 Problems and CIP Solutions.
Problem
• Pipe Deterioration: Several pipes
tributary to and along West Sylvester
Street in Basin 2 require rehabilitation
• Flooding: The existing facilities are
undersized and/or clogged. The travel
lanes flood during rain events. This is a
heavily trafficked industrial area
frequented by heavy trucks.
• Flooding: The existing facilities are
undersized and/or clogged. The
intersection with Robert Wayne Drive
floods, impeding the travel lane,
sidewalk, and a commercial driveway.
Burden Boulevard is a highly trafficked
roadway.
600 East A Street • Flooding: The low spot in the road
lacks stormwater infrastructure.
Roadside parking and an intersection
flood during rain events.
4416 Sedona Drive • Flooding: The existing facilities are
undersized and/or clogged. Both travel
lanes flood after large rain events, and
water is pushed into an adjacent
driveway and a private garage.
Schlagel Park • Pipe Deterioration
Stormwater Main
Stormwater Relining
(Phase 1)
Stormwater Relining
• Pipe Deterioration
• Pipe Deterioration
Solution
• Replace 500 linear feet of 21-inch-
diameter storm sewer pipe and
1,120 linear feet of 12-inch-diameter
storm sewer pipe. Install five (5)
48-inch-diameter maintenance holes.
• Install the design equivalent of
eighteen (18) Type II catch basins, each
connected to a 20-linear-foot
infiltration trench, within this drainage
area to manage the contributing
stormwater runoff.
• Install the design equivalent of five (5)
Type II catch basins, each connected to
a 20-linear-foot infiltration trench,
within this drainage area to manage the
contributing stormwater runoff. (This
project is included as part of the
Infiltration Improvements Program for
purposes of capital budget planning.)
• Install the design equivalent of five (5)
Type II catch basins, each connected to
a 20-linear-foot infiltration trench,
within this drainage area to manage the
contributing stormwater runoff. (This
project is included as part of the
Infiltration Improvements Program for
purposes of capital budget planning.)
• Install the design equivalent of eight (8)
Type II catch basins, each connected to
a 20-linear-foot infiltration trench,
within this drainage area to manage the
contributing stormwater runoff. (This
project is included as part of the
Infiltration Improvements Program for
purposes of capital budget planning.)
• Pipe Replacement (Details will be
developed at a future date by City
staff.)
• Pipe Relining along multiple roadways.
(See Table 4-5 for details.)
• Pipe Relining along multiple roadways.
(See Table 4-5 for details.)
a City to develop design in-house.
b Corresponds to N Sycamore Ave Infiltration Improvements identified in the 2016 plan.
Corresponds to Sylvester South Pipe Repair identified in the 2016 plan.
March 2023
6 HERRERA
City of Pasco Comprehensive Stormwater Management Plan - 2023 47
The following sections describe the types of solutions that have been developed. The solutions
fall into four categories: infiltration facility improvements, conveyance infrastructure
rehabilitation, water quality protection (developed in the 2016 plan), and stormwater code
violations (which are being resolved as needed by the City). In conjunction with the CIP solutions
in this section, the City should establish more protective design standards as discussed in
Section 5.
4.3.1. Infiltration Improvements
In areas that lack infiltration infrastructure, or suffer from poorly located, undersized or clogged
infrastructure, it is recommended that the stormwater system be expanded or replaced to
include appropriately sized infiltration facilities. As described in Section 3, updates to the City's
stormwater standards can help mitigate issues with the undersizing of future stormwater
facilities. In addition, improvements to the infiltration facility design standards would mitigate
future reductions in system performance from clogging.
There are different approaches the City can take to addressing the issue of clogged infiltration
systems. First, the City can increase the frequency of street sweeping throughout Basin 6 and
areas of Basins 1 through 5 that include infiltration facilities, especially before anticipated rain
events. Section 5.6 includes recommendations for programmatic changes in street sweeping and
maintenance frequency. Second, the design standard for infiltration trenches can be changed.
For example, installing upstream vaults or catch basins with baffles, removing the geotextile
fabric from the bottom of the trench, and/or installing a presettling vault ("fat pipe") between
the catch basin and the infiltration gallery could all increase the effective longevity of infiltration
systems and increase the efficacy of maintenance efforts. Finally, exploring surface infiltration
options, such as the non -vegetated bioswale currently being studied by the City (as discussed in
Section 5.8), may provide an easier -to -maintain infiltration option, depending on its
demonstrated effectiveness. Several of the projects that include proposed infiltration trenches
appear to have space in the right-of-way for a surface infiltration approach.
For the majority of Tier 1 projects that were identified during this planning effort, infiltration
improvements were the identified solution. In total, seven Tier 1 projects were identified that
required infiltration improvements; five of these projects have been bundled together and
included as part of the City's infiltration improvement program in Section 6.4. Design concepts
for these five projects are contained in the project summary sheets provided in Appendix C. One
of the infiltration improvement projects is associated with a larger stormwater pond retrofit and
is listed separately in Section 6.4; this project, too, has a corresponding project summary sheet in
Appendix C. Finally, one of the infiltration improvement projects (i.e., S Oregon Avenue) will be
designed by the City at a future date, and therefore no project summary sheet has been
provided.
* HERRERA
March 2023
48
City of Pasco Comprehensive Stormwater Management Plan — 2023
z�
i ier i t,ir- t-roiects
1
S Oregon Ave North of E Ainsworth St
2
127 S Hugo Ave
3
W Sylvester Pipe Repair
4
_
214/219 N Sycamore Ave
5
1801 N Commercial Ave
6
6415 Burden Blvd
7
600 East A St
8
4416 Sedona Dr
Legend
Figure 4-2.
CIP Project Locations Within the City
# Tier 1 CIP Project
Highway
of Pasco.
_I Pasco City Limits
Inlet
Urban Growth Area boundary
Manhole
N
J= Subbasin boundary
Main conveyance
0
River
Infiltration pipe
0 4,500 9,000 18.000
Stream
Street
Feel
HERRERA
Aen L MAI 2029
4.3.2. Conveyance Infrastructure Rehabilitation
As the City's buried stormwater conveyance system continues to age and deteriorate, it is
increasingly important that the City adopt a routine program for assessing and rehabilitating
damaged sections of pipe. This will include jet -cleaning and evaluating the condition of each
stormwater pipe with CCTV.
Stormwater pipes in Basin 2 were jet cleaned and evaluated for their condition and the
information was used to inform development of CIP projects for the 2016 plan. The results of
those evaluations are reflected in the West Sylvester Pipe Repair CIP project, which aims to
replace, or repair, identified damaged pipes. This project and its solution are presented in
Table 4-3.
A stormwater pipe relining program to address annual repair of failing pipes in the City's MS4
has been identified as a Tier 1 project and organized into two phases, as shown in Table 4-4.
Table 4-4. CIP Project/Program Descriptions and Capital Costs.
Project/Program Name
Description
S Oregon Avenue North
See project description in Table 4-3.
of E Ainsworth Streetb
Infiltration Improvements
This program will address infiltration issues throughout the City, as
Program
flooding is identified and/or reported and prioritized.
Sylvester Pipe Repair —
This project will repair or replace damaged stormwater conveyance
5th Ave to 10th Ave
system along Sylvester Street between 5th Avenue and 10th Avenue.
Pipeline inspection identified fractures in the existing pipeline.
N Commercial Ave
This project will install an underground infiltration system for the
Infiltration Pond Retrofit
stormwater runoff for the basin along North Commercial Avenue
and provide for potential new uses for this City -owned parcel as well
as reducing maintenance costs and increasing the effectiveness of
the system.
Schlagel Park
This project will replace aging stormwater pipe along the western
Stormwater Main
portion of Schlagel Park. The pipeline is 42 inches in diameter and
Replacement
damage extends for approximately 430 feet, including root intrusion
and previous lining failure.
Stormwater Relining
This project will:
(Phi
HERRERA
• Reline 348 LF of 30-inch concrete pipe under 1st Avenue
between W Lewis and W Columbia
• Reline 842 LF of 18-inch pipe tributary to Volunteer Park
• Repairjoint offsets with couplings between W Sylvester and
W Bonneville Streets
• Repair 3 slightly offsetjoints located north of W Bonneville
Capital Costa
$2,100,000
$930,000
$720,000
$710,520
$1,415,000
March 2023
50 City of Pasco Comprehensive Stormwater Management Plan — 2023
Table 4-4 (continued). CIP Project/Program Descriptions and Capital Costs.
Project/Program Name Description Capital Costa
Stormwater Relining This project includes the relining of existing aging stormwater $600,000
(Phase 2) pipelines, in the following locations:
• 8th Ave from W Margaret to W Park —15-inch diameter;
302.5 LF
• W Park from 8th to 5th —15 inch diameter; 958 LF
• W Park from 5th to 4th —18 inch diameter; 520 LF
• 5th Ave from W Park to W Nixon — 21 inch diameter; 318 LF
• 5th Ave from W Park to W Henry —15 inch diameter; 656 LF
This project will perform necessary repairs to the existing
stormwater system by relining and replacing some of the existing
pipes to prevent groundwater inflow into the system.
a Costs developed in 2022 dollars.
b City to develop design in-house; design and implementation costs have not been included in the CIP planning budget.
LF = linear feet
4.3.3. Water Quality Protection
As part of the 2016 plan, two approaches to water quality protection were considered for those
basins that outfall directly to the Columbia River. The first was to eliminate the outfalls by
implementing basin -wide infiltration retrofits, and the second was to provide treatment at
regional facilities located at the downstream end of the basins. Both approaches are described
in Section 4.2.2 of the 2016 plan. These projects have not been implemented and are retained as
potential long-term CIP projects.
No other projects that would protect water quality have been identified as part as the current
plan, and no modifications have been made to the water quality projects from the 2016 plan. As
water quality permitting requirements continue to become more stringent, these water quality
protections may become increasingly relevant to City planning in future CIPs.
4,3,3,1, Stormwater Code Compliance
As described in Section 4.2.4, the City has addressed all recent stormwater code violations. The
City should continue these practices of addressing emergent stormwater code violations as they
arise.
March 2023
* HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 51
This page intentionally left blank
5. STORMWATER MANAGEMENT
PROGRAM EVALUATION AND
RECOMMENDED ACTIVITIES
The current NPDES permit was effective as of August 2019. It reflected an expansion of activities
and requirements from the previous NPDES permit. The City of Pasco has been adapting its
program to meet the 2019-2024 NPDES permit requirements and faces staffing issues, similar to
other Eastern Washington permittees. This section provides a summary of the City's current
stormwater management program and an assessment of its compliance with the NPDES permit.
Generally, the City is on track for meeting the NPDES permit requirements as summarized
below.
The following section is organized to reflect the organization of the NPDES permit. For each
topic heading (or permit section) a general summary of permit requirements is provided, along
with a summary of the additional resources, such as staffing or funding, that are needed to
implement the recommended activities. Where applicable, a table listing identified
recommended activities for program improvement is provided. These recommended activities
were developed based on responses to a questionnaire that was filled out by various City staff
and a follow up workshop that focused on the City's current activities to meet the NPDES permit
requirements. The current activities and questionnaire are summarized in Appendices A and B,
respectively. Each recommended activities table provided in this section indicates whether the
recommended activity is required to meet permit requirements; provides a high, medium, and
low ranking of the recommended activity; and summarizes expected staff or funding support
required for implementation. Funding support is typically recommended for discrete or one-
time tasks that can be supported by consultants or contractors allowing City staff to focus on
ongoing NPDES permit requirements. Staffing support is typically recommended for ongoing
NPDES permit requirements. In addition to the staffing support included in this section for
recommended activities, it is also noted that the City currently has open staff positions that are
funded, but is having difficulty filling these positions given the staffing shortage experienced
across the region, and even across the country.
Only recommended activities that reflect a NPDES permit requirement are ranked as a high
priority. Although not required to meet the 2019-2024 NPDES permit requirements, it is
recommended that the City staff and decision makers consider the positive impacts of the
medium and low priority recommended activities on meeting the City's long-term goals as these
activities will result in greater benefits for both the community and the environment.
March 2023 * HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 53
5.1. PUBLIC EDUCATION AND OUTREACH
The Public Education and Outreach section of the NPDES permit requires education and
outreach to school -age children, adults, and overburdened communities as well as specific
audiences (e.g., engineers, contractors, and developers). The City meets these requirements by
contracting with the Franklin Conservation District (FCD) and coordinating with the other
Quad -Cities (i.e., Kennewick, Richland, and West Richland). Activities include supporting
curriculum at schools (e.g., participating in the Drain Rangers program and Wheat Week), the
Regional Home and Garden Show, and the Benton -Franklin Fair and Rodeo. The City's
stormwater web page also provides easy access to stormwater information and resources.
Table 5-1 includes a list of recommended activities for improving the public education and
outreach component of the stormwater management program.
The City currently has 0.05 full-time equivalent (FTE) allocated to support stormwater public
education and outreach. The additional recommended activities identified can be met through
expansion of existing activities or through funding for outside resources to develop curriculum
or materials. An additional $12,000 of one-time funding and 0.09 FTE of ongoing staffing is
estimated to be needed to support all of the activities summarized in Table 5-1.
Table 5-1. Recommended Activities for Public Education and Outreach.
Priority
Additional
Permit
(high/
Support
Requirement
medium/
Needed
Recommended Activities
(yes/no)
low)
(staff/funding)
Support Assumptions
Audience: All
Develop a schedule for web page
Yes
High
NA
To be addressed as part
updates and development/
of current staff
distribution of education and outreach
responsibilities.
materials
_
City stormwater web page updates:
Yes
High
NA
To be addressed as part
• Post available brochures (e.g., Only
of current staff
Rain Down the Drain, Storm Drains)
responsibilities.
• Add information and links
regarding illicit discharges and
business education materials
• Remove link to Eastern Washington
LID Guidance Manual
• Add a link to the City's municipal
stormwater code
Audience: Businesses
Provide educational materials to
Yes
High
NA
To be addressed as part
support the City's business outreach
of current staff
program
_
responsibilities.
Consider conducting targeted outreach
No
Medium
160 hours/year
1 week per quarter
to businesses
(0.09 FTE)
(40 hours x 4 quarters =
160 hours annually).
HERREK,
March 2023
City of Pasco Comprehensive Stormwater Management Plan - 2023
Table 5-1 (continued). Recommended
Activities for Public Education
and Outreach.
Priority
Additional
Permit
(high/
Support
Recommended Activities
Requirement medium/ Needed
(yes/no) low) (staff/funding)
developers, development review staff,
Support Assumptions
and land use planners
Audience: Engineers, construction contractors,
Develop education and outreach
Yes
High
NA
To be addressed as part
materials for engineers, construction
of current staff
contractors, and develo ers
res onsibilities.
Yes
High
NA
To be addressed as part
Conduct internal staff training for
development review staff and land use
of current staff
tanners related to these topics
responsibilities.
No
Medium
$6,000
Update the City's development
40 consultant hours at
handouts to include information
$150/hour to develop
regarding stormwater.
materials and present
Host a stormwater workshop for No
Medium $6,000 40 consultant hours at
contractors, developers, and
$150/hour to develop
consultants every 1 to 2 years to
materials and present
provide updated stormwater
workshop.
information
High Priority Subtotal
One-time funding/staffing: NA
Ongoing staffing: NA
Medium Priority Subtotal
One-time funding/staffing: $12,000
Ongoing staffing: 0.09 FTE
Low Priority Subtotal
One-time funding/staffing: NA
Ongoing staffing: NA
Grand Total
One-time funding/staffing: $12,000
Ongoing staffing: 0.09 FTE
FTE = full-time equivalent
LID = low impact development
NA = not applicable
March 2023
Oj HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 55
5.2. PUBLIC INVOLVEMENT AND PARTICIPATION
The Public Involvement and Participation section of the NPDES permit is about ensuring the
public has opportunities to provide input into the decision -making process related to
stormwater management. Currently, the City meets this permit requirement by discussing
stormwater-related problems or providing information at City Council sessions and inviting
public comment, as well as through development and posting of annual stormwater reports and
by accepting comments and addressing questions through the stormwater hotline and the front
desk. Only one recommended activity was identified related to this permit section (Table 5-2).
No additional staff or funding has been identified to support this permit section.
Table S-2. Recommended Activities for Public Involvement and Participation.
Recommended Activities
Consider incorporating stormwater
education as a topic for City Council
meetings, including a brief overview of
stormwater issues, illicit discharges, and
available information.
High Priority Subtotal
Medium Priority Subtotal
Low Priority Subtotal
Grand Total
FTE = full-time equivalent
NA = not applicable
4 HERRERA
Priority
Permit (high/
Requirement medium/
(yes/no) low)
No Low
Additional
Support
Needed
Support
(staff/funding)
Assumptions
NA
To be addressed
as part of
current staff
responsibilities.
One-time funding/staffing: NA
Ongoing staffing: NA
One-time funding/staffing: NA
Ongoing staffing: NA
One-time funding/staffing: NA
Ongoing staffing: NA
One-time funding/staffing: NA
Ongoing staffing: NA
March 2023
56 City of Pasco Comprehensive Stormwater Management Plan - 2023
5.3. ILLICIT DISCHARGE DETECTION AND ELIMINATION
The Illicit Discharge Detection and Elimination (IDDE) section of the NPDES permit has an
extensive list of specific and general requirements including mapping, implementation of
ordinances or other regulatory actions, enforcement, field screening, identification of priority
areas, development of field assessment procedures, training, education, and other activities.
Table 5-3 provides a summary of recommended activities for improving the IDDE component of
the stormwater management program. The majority of the recommended activities are one-time
tasks related to revising the PMC, developing written methodologies, and improving
documentation and, therefore, do not require extensive additional work or resources.
The City currently has 0.03 FTE allocated to support IDDE. No additional ongoing activities were
identified that would require permanent staff support, so no additional staff were recommended
to meet IDDE program needs. One-time funding needs are estimated to be $21,000 for a spill
response flow chart and geographic information system (GIS) updates. Ongoing (annual)
funding needs for replacement and/or restocking of equipment are discussed in Section 6.3.
Table 5-3. Recommended Activities for
Illicit Discharge Detection and Elimination.
Recommended Activities
Priority
Permit (high/
Requirement medium/
(yes/no) low)
Additional
Support
Needed
Update the City's MS4 map by August 1, 2023 Yes High $6,000
with outfall size and material, discharge
points, areas that do not discharge to surface
receiving waters, and connection points after
August 1, 2019.
Create a spreadsheet that lists the known Yes High NA
outfalls and discharge points, including the
outfall's size and material by August 1, 2023.
Develop GIS shapefiles for ditches, irrigation No Low $6,000
channels, and curb and gutter areas.
Support
Assumptions
Assumes
40 consultant hours
at$150/hour to
update the MS4
map based on
desktop review. This
does not include
any associated field
work.
Addressed by
consultant
supporting MS4
map updates.
Assumes
40 consultant hours
at$150/hour to
develop shapefiles
based on desktop
review. This does
not include any
associated field
work.
March 2023 HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
Table 5-3 (continued). Recommended Activities for
Illicit Discharge Detection and Elimination.
Priority
Permit (high/ Additional
Requirement medium/ Support Needed
Recommended Activities (yes/no) low) (staff/funding)
Incorporate Franklin County data within the No Low $6,000
UGA into GIS shapefiles for ditches, irrigation
channels, and curb and gutter areas.
Update PMC Chapter 13.80 (1) Discharges
from water pipe sources and (3) Water used to
wash down streets, sidewalks, and buildings
for consistencv with the NPDES Dermit.
Shift "active construction sites" from 13.80.120
to 13.80.090 or 13.80.100.
Consider revising PMC Chapter 1.40
applicability to include Title 14 - Public Works
and Title 23 - Environmental Imoact.
Develop a compliance strategy before
February 2, 2023.
Work with the Maintenance division and Parks
Department to develop a City -specific illicit
discharge field screening methodology.
Add field screening methods to the City's Spill
Response Plan and Policy Procedure Program.
Add a checkbox to maintenance field forms to
document whether illicit discharges were
detected during routine catch basin, manhole,
and outfall inspections.
Improve public illicit discharge identification
(see Public Education and Outreach).
Consider developing a flyer showing a flow
chart or other graphic instruction that outlines
the process for responding to spills and
providing the flyer to spill -vulnerable
businesses. Consider requiring those
businesses to post the flyer in a conspicuous
location.
HERRERA
58
Yes High
No Medium
No Medium
Yes High
Yes Medium
Yes High
Yes High
- Addressed in Public
No Medium
March 2023
City of Pasco Comprehensive Stormwater Management Plan - 2023
NA
Support
Assumes
40 consultant hours
at $150/hour to
update shapefiles
based on desktop
review. This does
not include any
associated field
work.
To be addressed as
part of current staff
responsibilities.
NA
To be addressed as
part of current staff
responsibilities.
NA
To be addressed as
part of current staff
responsibilities.
NA
To be addressed as
part of current staff
responsibilities.
To be addressed as
NA
part of current staff
responsibilities.
NA
To be addressed as
part of current staff
responsibilities.
NA
To be addressed as
part of current staff
responsibilities.
Education and
Outreach, above.
$3,000 20 consultant hours
at $150/hour.
Table 5-3 (continued). Recommended Activities for
Illicit Discharge Detection and Elimination.
Priority
Permit (high/ Additional
I Requirement medium/ Support Needed
Support
Recommended Activities
(yes/no)
low)
(staff/funding)
Assumptions
Yes
Medium
NA
To be addressed as
Develop a map that identifies priority areas
prone to illicit discharges. Track reported illicit
part of current staff
discharges, inspections, and outreach
responsibilities.
performed in these areas.
No
Medium
NA
Establish a web -based form for the public to
Web -based form to
file stormwater complaints. Consider allowing
be developed by
complaints to be filed anonymously.
internal staff.
Yes
High
NA
To be addressed as
Expand IDDE Awareness level training
audience to include building inspectors.
part of current staff
responsibilities.
No
Low
NA
Consider expanding IDDE Awareness level
To be addressed as
training to police officers, fire fighters, health
part of current staff
department staff, and animal control officers.
responsibilities.
Maintain staff training records in an electronic
Yes
Medium
NA
To be addressed as
database, including training dates, activities or
part of current staff
course descriptions, and names and positions
responsibilities.
of staff in attendance.
Electronic database
is not specified in
the NPDES permit,
but it will be useful
for ongoing
tracking.
Yes
High
NA
Develop new outreach materials for illicit
To be addressed as
discharge hazards education.
part of current staff
responsibilities.
Train Fire Department and Police Department
No
Medium
NA
JTo be addressed as
to identify and respond to illicit discharges as
part of current staff
art of the training program.
NA
responsibilities.
Add Ecology illicit discharge reporting
Yes
High
To be addressed as
requirements to the City of Pasco Spill
part of current staff
Response Plan Policy and Procedure Program.
responsibilities.
Include field screening methodologies,
Yes
High
NA To be addressed as
procedures for follow-up inspections, and
part of current staff
references to PMC, Chapter 1.40, for
responsibilities.
enforcement and escalation, in the Spill
Response Plan Policy and Procedure.
Consider hosting an IDDE response and
Yes
High
NA To be addressed as
enforcement training in 2023. Modify
part of current staff
curriculum to focus on source tracing and
responsibilities.
enforcement.
March 2023
City of Pasco Comprehensive Stormwater Management Plan — 2023
* HERRERA
S9
Table 5-3 (continued). Recommended Activities for
Illicit Discharge Detection and Elimination.
Priority
Permit (high/ Additional
Requirement medium/ Support Needed Support
Recommended Activities (yes/no) low) (staff/funding) Assumptions
High Priority Subtotal One-time funding/staffing: $6,000
Ongoing staffing: NA
Medium Priority Subtotal One-time funding/staffing: $3,000
Ongoing staffing: NA
ILow Priority Subtotal One-time funding/staffing: $12,000
Ongoing staffing: NA
Grand Total One-time funding/staffing: $21,000
L Ongoing funding: NA
FTE = full-time equivalent GIS = geographic information system
IDDE = illicit discharge detection and elimination MS4 = municipal separate storm sewer system
NA = not applicable NPDES = National Pollution Discharge Elimination System
PMC = Pasco Municipal Code
I" ERREM March 2023
60 City of Pasco Comprehensive Stormwater Management Plan — 2023
5.4. CONSTRUCTION SITE STORMWATER RUNOFF CONTROL
The Construction Site Stormwater Runoff Control section of the NPDES permit includes
requirements related to ordinance development, inspection and enforcement, site plan review,
training (including site plan, inspection/enforcement, and erosion control), and recordkeeping.
The City's program currently meets many of these requirements. Table S-4 lists recommended
activities for improving the construction site stormwater runoff control component of the
stormwater management program. Most of the recommended activities are required to be in
compliance with the NPDES permit, but are one-time tasks related to revising the PMC,
developing written methodologies, and improving documentation; therefore, they do not
require extensive additional work or resources.
The stormwater utility does not currently fund any staff to support construction site stormwater
runoff control because related activities are completed through existing City programs. No
additional staffing and funding needs were identified.
Table 5-4. Recommended Activities for
Construction Site Stormwater Runoff Control.
Priority Additional
Permit
(high/ Support
Requirement
medium/ Needed
Recommended Activities
(yes/no)
_ low) (staff/funding)
Support Assumptions
Update PMC to shift "active
No
Medium NA
To be addressed as part of
construction sites" from
current staff responsibilities.
13.80.120 to 13.80.090 or
13.80.100.
Yes/No
High
NA
Require that stormwater
Required for newer projects,
designers and engineers use
but not for older projects
the SWMMEW when designing
and not for those that fall
stormwater facilities.
under certain thresholds.
No
Consider requiring or
Medium
NA
To be addressed as part of
encouraging pre -application
current staff responsibilities.
meetings for construction
permits.
High NA
Consider hosting an inspection
Yes
To be addressed as part of
and enforcement training in
current staff responsibilities.
2023.
Yes
Maintain staff training records
Medium NA
To be addressed as part of
in an electronic database,
current staff responsibilities.
including training dates,
Electronic database is not
activities or course descriptions,
specified in the NPDES
and names and positions of
permit, but it will be useful
staff in attendance.
Provide information regarding
Medium NA
for ongoing tracking.
To be addressed as part of
Yes
available erosion control
current staff responsibilities.
trainings to site operators.
March 2023
4 HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 61
Table 5-4 (continued). Recommended Activities for
Construction Site Stormwater Runoff Control.
Recommended Activities
High Priority Subtotal
Medium Priority Subtotal
Low Priority Subtotal
Grand Total
Priority
Permit (high/
Requirement medium/
(yes/no) low)
CIP = capital improvement plan
FTE = full-time equivalent
NA = not applicable
NPDES = National Pollution Discharge Elimination System
PMC = Pasco Municipal Code
SWMMEW = Stormwater Management Manual for Eastern Washington
4 HEPMERA
Additional
Support
Needed
(staff/funding) Support
One-time funding/staffing: NA
Ongoing staffing: NA
One-time funding/staffing: NA
Ongoing staffing: NA
One-time funding/staffing: NA
Ongoing staffing: NA
One-time funding/staffing: N
Ongoing staffing: NA
March 2023
62 City of Pasco Comprehensive Stormwater Management Plan — 2023
5.5. POST -CONSTRUCTION STORMWATER MANAGEMENT
The Post Construction Stormwater Management section of the NPDES permit includes similar
requirements to the Construction Site Stormwater Runoff Control section, including ordinance
development, inspection and enforcement, site plan review, training (including site plan and
design), inspection/enforcement and erosion control), and pertinent documentation. The City
currently meets most of the NPDES permit requirements. Table 5-5 lists recommended activities
for improving the post construction stormwater management component of the stormwater
management program. The Stormwater utility does not currently fund any staff to support
existing activities for this NPDES permit section. It is expected that an additional 0.125 FTE for a
site plan reviewer will be needed to address development for annexed areas. One-time funding
needs include $4,500 for code updates and LID training materials.
Table 5-5. Recommended Activities for Post -Construction Stormwater Management.
Priority
Additional
Permit
(high/
Support
Requirement
Recommended Activities (yes/no)
medium/
low)
Needed
(staff/funding)
Support Assumptions
Add a provision to the PMC for Yes
High
$1,500
10 consultant hours at
inspection access for stormwater
$150/hour to develop
BMPs on private properties that
this code/ordinance
discharge to the MS4. J_
Ian ua e.
Medium
Additional training may be No
$3,000
20 consultant hours at
needed related to reviewing LID
$150/hour to develop
BMPs and TAPE -approved
materials and present
technologies.
training.
Provide information regarding
Yes
Medium
NA
To be addressed as part
available design trainings to
of current staff
design professionals.
res onsibilities.
No
Low
Staff resources to perform site
0.125 FTE
Assumes additional
plan review for development
plan review staff time
projects within the UGA.
will be needed for
newly annexed area.
High Priority Subtotal
Medium Priority Subtotal
Low Priority Subtotal
Grand Total
BMP = best management practice
LID = low impact development
NA = not applicable
PMC = Pasco Municipal Code
March 2023
One-time funding/staffing: $1,500
Ongoing staffing: NA
One-time funding/staffing: $3,000
Ongoing staffing: NA
One-time funding/staffing: NA
Ongoing staffing: 0.125 FTE
One-time funding/staffing: $4,500
Ongoing staffing: 0.125 FTE
FTE = full time equivalent
MS4 = municipal separate storm sewer system
NPDES = National Pollution Discharge Elimination System
TAPE = Technology Assessment Protocol Ecology
4 HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
63
5.6. MUNICIPAL OPERATIONS AND MAINTENANCE
The municipal and operations and maintenance (O&M) section of the NPDES permit includes
requirements for scheduling and carrying out O&M activities at City owned facilities, inspection
of those facilities, and related recordkeeping and training. It also requires development and
implementation of a stormwater pollution prevention plan (SWPPP) for certain City facilities.
Table 5-6 includes a list of recommended activities for improving the municipal O&M
component of the stormwater management program.
The City currently has approximately 2.0 FTE allocated to support municipal O&M. Additional
staff will be needed to support the recommended activities listed in Table 5-6. Ongoing (annual)
staffing needs are 5.25 FTE to support operation and maintenance of stormwater facilities. These
staff will serve a dual role for conducting private stormwater facility inspections identified in the
previous section. One-time staffing needs of 160 hours have also been identified.
Table 5-6. Recommended Activities for
Municipal Operations and Maintenance.
Priority
Additional
Permit
(high/
Support
Requirement
medium/
Needed
Recommended Activities
(yes/no)
Yes
low)
High
(staff/funding)
Support Assumptions
Update definitions adeferences
NA
To be addressed as part of
to the NPDES permit in the O&M
current staff responsibilities.
Plan to be consistent with current
permit requirements and the
SWMMEW.
Yes
High
NA
To be addressed as part of
Ensure all inspection and
maintenance logs and
current staff responsibilities.
documentation are filled out and
stored in a database.
No
Medium
Conduct condition assessment of
2.0 FTE +Staff
required to operate the
the stormwater system on a
(ongoing)CTV-equipped
van, review
5-year cycle.
video logs, enter information
into an electronic database,
and identify pipe repair
and/or replacement projects.
Basins assumed to be video
inspected on a 5-year cycle._
Assumes 4 weeks at
Convert hard copy map book and
No
High
160 hours
tracking to Cartegraph.
(one time)
40 hours/week.
Yes
High
Update the SWPPP.
NA
Ongoing updates to occur as
part of current staff
responsibilities.
HERRERA March 2023
64 City of Pasco Comprehensive Stormwater Management Plan — 2023
Table 5-6 (continued). Recommended Activities for
Municipal Operations and Maintenance.
Recommended Activities
Consider hosting an O&M
training in 2023. Expand O&M
training to include all
maintenance, Wastewater,
Roads, and Parks staff at the time
of hire and annually.
Review the City O&M Plan and
City SWPPP at ongoing trainings.
Track training records, including
dates, activities or course
descriptions, and names and
positions of staff in attendance
using an electronic database.
Inspect, clean, and maintain
catch basins, inlets, and
infiltration facilities.
Repair damaged stormwater l
treatment and flow control
facilities after spot checks.
Inspect, clean, and maintain
catch basins, inlets, and
infiltration facilities within the
UGA.
High Priority Subtotal
Medium Priority Subtotal
Low Priority Subtotal
Grand Total
Permit
Requirement
(yes/no)
Yes
CCTV = closed-circuit television
NA = not applicable
O&M = operations and maintenance
SWPPP = stormwater pollution prevention plan
March 2023
Priority
Additional
(high/
Support
medium/
Needed
low)
(staff/funding)
High
NA
Yes High NA
No Medium NA
Yes High 2.0 FTE
Yes High 1.0 FTE
No
Support Assumptions
To be addressed as part of
current staff responsibilities.
To be addressed as part of
current staff responsibilities.
To be addressed as part of
current staff responsibilities.
Electronic database is not
specified in the NPDES
permit but will be useful for
ongoing trackin . _
No new FTEs (assumes
vacant positions are filled).
No new FTEs (assumes
vacant positions are filled).
Low 0.25 FTE No new FTEs (Assumes
vacant positions are filled).
This includes additional staff
time may be needed for
additional annexed area.
One-time funding/staffing: 160 hours
Ongoing staffing: 3.0 FTE
One-time funding/staffing: NA
Ongoing staffing: 2.0 FTE
One-time funding/staffing: NA
Ongoing staffing: 0.25 FTE
One-time funding/staffing: 160 hours
Ongoing staffing: 5.25 FTE
FTE = full time equivalent
NPDES = National Pollution Discharge Elimination System
SWMMEW = Stormwater Management Manual for Eastern Washington
4 HERRERA
City of Pasco Comprehensive Stormwater Management Plan - 2023
65
5.7. TOTAL MAXIMUM DAILY LOAD REQUIREMENTS
The City has no specific TMDL requirements, and no program gaps or recommended activities
related to the TMDL section of the NPDES permit. No additional staff or resources have been
identified.
5.5. MONITORING AND ASSESSMENT
The Monitoring and Assessment section of the NPDES permit requires that the City report on
any monitoring or stormwater related studies in its annual report and that the City collaborate
with other Eastern Washington jurisdictions to develop stormwater effectiveness studies. The
City recently participated in and reviewed Yakima County's BMP Inspection and Maintenance
Responsibilities effectiveness study. Currently, the City is working on two Quad -Cities
effectiveness studies on non -vegetated biofiltration swales and paired basins street sweeping.
The City has supported these effectiveness studies by assisting with a detailed study design
proposal, and plans to support the completion of an Ecology -approved Quality Assurance
Project Plan (QAPP), which is due July 31, 2023, and completing the study on or before
December 1, 2023. It is expected that this work will be addressed as part of current staff
responsibilities.
City staff are also virtually participating in the Eastern Washington Stormwater Managers Group
to incorporate comments into the next round of revisions to the NPDES permit. Therefore, the
City meets all of the current requirements of this section; no program gaps or additional staff
needs have been identified.
5.9. REPORTING AND RECORDKEEPING
The Reporting and Recordkeeping section of the NPDES permit requires that the City submit an
annual report of activities, and that it maintains records for 5 years and make records available
to the public. It also requires that the City tracks the estimated cost of development and
implementation of each component of their Stormwater Management Plan (SWMP). The City
submits an annual report of activities, maintains records for 5 years, and make records available
to the public. The City is also required to track the estimated cost for implementing the SWMP,
but no additional staff or resources are needed to support this task.
* HERRERA
March 2023
66
City of Pasco Comprehensive Stormwater Management Plan — 2023
5.10. UPDATE TO CITY CODE AND DESIGN STANDARDS
As listed above in Sections 5.3 through 5.5, updates to the PMC are needed to remain in
compliance with the NPDES permit requirements, but it may also be necessary to develop an
addendum/supplement to the SWMMEW to include additional design standards for elements
not addressed in the SWMMEW. This includes detailed design guidance for:
a Low impact development (LID) best management practices (BMPs), such as bioretention
and permeable pavement. Guidance for Eastern Washington is covered in the SWMMEW,
but City -specific design requirements may need to be established.
Updates to infiltration trench design standard, to reduce the potential for clogging.
Section 4.3.1 contains potential strategies for addressing chronic clogging issues through
design changes.
The design standards, including sizing and layout, for these elements should be explicitly
covered in the PMC and/or a City amendment/supplement to the SWMMEW.
The City's review of drainage plans would also benefit from more specific design standards,
particularly for sizing. Multiple projects that were identified for rehabilitation during this
planning process are a result of undersized and poorly designed facilities, which could have
been prevented during the site plan review stage. Specific guidance should also be developed
for construction and inspections of temporary erosion and sediment control measures and
proper installation of stormwater facilities.
In addition, stormwater requirements are addressed in multiple chapters of the PMC, making it
difficult for developers, designers, and reviewers to track specific requirements. The City should
consider reorganizing its code to include all general stormwater requirements in one section of
the code. The City may want to consider developing its own stormwater design manual, or a
detailed amendment to the SWMMEW, and modifying the PMC to remove specific design
information and to reference the design guidance instead. This would prevent inconsistencies
between the PMC and the stormwater design manual and would also make it easier to revise
design standards without going through a formal code adoption process.
( HERRERA
March 2023
City of Pasco Comprehensive Stormwater Management Plan — 2023 67
This page intentionally left blank
6. PLAN IMPLEMENTATION
6.1. NPDES PERMIT TIMELINE
Table 6.1 includes the upcoming NPDES permit requirements organized by due date. This table
does not include ongoing activities.
Due Date
Table 6-1. NPDES Permit Timeline.
Activity NPDES Permit Section
2023
February 2, 2023 Update IDDE regulatory mechanism, if
needed.
July 31, 2023 Submit completed CAPP.
August 1, 2023
August 1, 2023
December 1, 2023
MS4
Collect size and material for all known MS4
outfalls.
SS.B.3. Illicit Discharge Detection and
Elimination
S8.A. Stormwater Management Program
Effectiveness Studies
S5.B.3. Illicit Discharge Detection and
Elimination
Begin conducting study (or within 3 months S8.A. Stormwater Management Program
of Ecology approval). Effectiveness Studies
2024
February 2, 2024
for permit renewal.
NPDES = National Pollution Discharge Elimination System
IDDE = Illicit Discharge Detection and Elimination
QAPP = Quality Assurance Project Plan
MS4 = Municipal Separate Storm Sewer System
6.2. STAFFING NEEDS
G18. Dutv to Rea ppl,
Table 6-2 provides a summary of current and additional staffing and consultant needs (as
identified in Section 5) for implementing the City's stormwater management program. The City
currently has approximately 2.51 full -time -equivalent (FTE) that support stormwater program
activities (0.37 FTE) and/or stormwater maintenance (2.14 FTE) funded through the stormwater
utility. An additional approximately 1.41 FTE are funded through the City's general fund. These
staff provide stormwater engineering support through the City's Community and Economic
Development department for activities such as plan review and site inspections. In total, there
are approximately 3.92 FTE supporting the stormwater management program. It is assumed
these FTE will continue to be funded through the same funding sources. The additional staff
support needs identified in Table 6-2 are those associated with carrying out the high priority
activities identified in Section 5 of this plan.
March 2023
qu HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
MJ
Table 6-2. Current and Recommended City of Pasco SWMP Staff and Consultant Needs
to Support Ongoing Activities.
Full -Time Equivalent (FTE) Staff
Additional Support
Current Staff (2023) Needed
Position/Department Funding/Staffing
Stormwater Programa One-time funding/staffing
Stormwater Maintenanceb I One-time
Community and Economic
Development`
Totals
Ongoing staffing
One-time fundinq/sta
One-time funding/staffing
Positions Funded and
Staffed
Not applicable
0.37 FTE
Not applicable
2.14 FTE
Not applicable
1.41 FTE
Not applicable
3.92 FTE
High Priority Activities
0 FTE
160 hours'
3.0 FTE'
$1,500,
0 FTE
160 hours/$7,500
3.00 FTE
a Stormwater Program includes staff from the CIP Engineering Division (Public Works) and Planning Division (Community &
Economic Development).
b Stormwater Maintenance includes staff who perform video and private stormwater facility inspections.
Community and Economic Development includes staff who perform plan review and construction inspections.
d Funding needed for City mapping updates. See Table 5-3 for more information about the recommended activity and funding
assumptions.
e Staffing needed for Stormwater maintenance staff. See Table 5-6 for more information about the recommended activity and
staffing assumptions.
f Funding needed for code/ordinance updates. See Table 5-5 for more information about the recommended activity and funding
assumptions.
Before the 2016 plan, the City purchased a van equipped with closed circuit television (CCTV),
but it currently does not have staff available to operate the van and conduct routine video
inspections of the stormwater pipe network to identify deficiencies. Two additional FTE
stormwater maintenance staff are needed to carry out that activity; these additional staff could
also support the private stormwater facility inspection program identified in Table 5-5. A small
increase in staffing was also identified to support public education and outreach for the
stormwater management program (included in Table 5-1). The total additional staffing need for
low, medium, and high priority activities is estimated at 5.09 FTE. For simplicity, only the high
priority activities were included in Table 6-2. The additional staffing need for the high priority
activities is estimated at 3.00 FTE. These 3.00 FTE would implement the following activities:
* Inspecting, cleaning, and maintaining catch basins, inlets, and infiltration facilities
s Repairing damaged stormwater treatment and flow control facilities after spot checks
HERRERA
March 2023
70
City of Pasco Comprehensive Stormwater Management Plan — 2023
6.3. EQUIPMENT NEEDS
The major City equipment currently used for stormwater management includes two Vactor
trucks (although the City has only one Vactor crew), four street sweepers, and a CCTV -equipped
van. The City also purchased an unlimited Cartegraph license (a software program used for
tracking asset, work, space, and operations management) through a grant from Ecology.
Table 6-3 lists the City's current equipment as well as new equipment that is recommended for
field screening and source tracing. Estimated costs for purchasing the recommended equipment
are $3,000 plus an annual replacement cost of $1,000.
Table 6-3. Current and Recommended
Equipment
2009 Elgin Whirlwind Street Sweeper
2011 Elgin Whirlwind Street Sweeper
2015 Elgin Whirlwind Street Sweeper
2022 Elgin Whirlwind Street Sweeper
Vactor truck
CCTV equipped van
Cartegraph license
Field screening and source tracing
equipmentb
• High-powered lamps (rechargeable
spotlight)
• Mirror and pole
• Dye testing supplies
• Ammonia test strips
• pH probe (with temperature probe)
• Turbidity meter
• Surfactant test kit
• Nitrile gloves
• Claw grabber
• Swing sampler or telescoping dipper
• Laboratory grade cleaning wipes
• Wash bottle
• Sample bottles
March 2023
Current
Equipment
(2023)
1
1
1
1
2
1
Unlimited
Limited
of Pasco SWMP Equipment.
Notes
Equipment Cost'
Not applicable
Will be decommissioned
once the street sweeper
arrives
Not applicable
Not a plicable
Order in progress
Not applicable
Not applicable
Not applicable
Not applicable
$3,000 (one time)
Limited equipment and
supplies are currently
available for use, so new
equipment purchases
are recommended
* HERRERA
City of Pasco Comprehensive Stormwater Management Plan - 2023 71
Table 6-3 (continued). Current and Recommended City of Pasco SWMP Equ
Field screening and source tracing
equipment refills
• Dye testing supplies
• Ammonia test strips
• pH buffer solutions
• Turbidity standard solutions
• Surfactant test kit refills
• Nitrile gloves
• Laboratory grade cleaning wipes
• Sample bottles
Total
Current
Equipment
(2023)
None
Notes Equipment Cost'
After the initial $1,000 (annual)
equipment and supplies
are purchased, this is a
recommended list of
equipment to be
refilled/restocked each
year
One-time funding:
$3,000
Ongoing/annual
funding: $1,000
a Equipment costs are considered not applicable for items that were purchased previously.
b Field screening and source tracing equipment recommendations from the Illicit Connection and Illicit Discharge Field Screening
and Source Tracing Guidance Manual (Herrera and Aspect 2020).
* HEItRERA
March 2023
72 City of Pasco Comprehensive Stormwater Management Plan — 2023
6.4. CAPITAL IMPROVEMENT PROGRAM NEEDS
The CIP projects are described in Section 4. Table 6-4 presents an implementation schedule that
balances project priority and available funding. The project implementation schedule was
developed by City staff and was based on their priorities and expectations at the time this plan
was developed. South Oregon Avenue North of East Ainsworth Street was scheduled first
because the City plans on developing the design in-house. North Sycamore Avenue Infiltration
Improvements was scheduled second because of the severity and frequency of flooding and the
high cost for maintenance at this site.
In addition to implementation of the projects and funding described in other sections of this
plan, the City should take the following steps related to CIP planning:
The Stormwater Program staff should meet at least annually with all Public Works
Operations staff to:
Identify any new problems that should be added based on field observations or
system inspection data.
b. Revisit project priorities by reconsidering the risk posed by known problems.
c. Adjust the CIP list, web map, and priorities, including updating the 6-year
implementation schedule, based on the output of Steps a and b above.
2. Review the CIP section when this plan is updated. Use the CIP prioritization framework to
justify adding, removing, or modifying projects.
March 2023
4 HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023 73
i
o
Go
0
w
OO
O
NI
CD
O
�f
ts�
Ln
to
01
W
O
O
1.4
CDCD
vOh
O
p
cmI
O
m
O
O
O
O
O
<D
O
O
V
G�
ey
O
I
CD
ti4
CD
t,9
O
N
aA
r
s
N
v
LM
Ln
Ln
-b�
�bq
v�
H
`
=
d-
O
�.
a+
O
o
o
p
E
N
CD
N
Ln
r
M
64
b4
ts'}
M
E
O
O
O
O
N
cq
CD
CD
Ln
fm
I
Cl
CD
4A.
CD%
Ln
v�
Le
O
N
Ln
O
�Y
O
W
>
�
O
O
O
o
�.
N
I
O
O
^
O
O
vOR
v04
604
N
O
tR
iA
b4
1R
a+
.�
Co
Co
V
u°
Ln
o
0
I
o
C
00
0
C
cn
d1
N
I-
O
�
F
d4
6�
�
Vi
44
v3
Y
f0
N
O
O
C
c
z
>
a)
a
too
ar
v
Q¢
¢ m
l0
C
0
p
0 E
'6 O
N
N N
F
Z
L
N
N
n m
v
'u c
O_
y¢
3
"M v
O
a +'
E c
p
d
E
m
t
M
`m t
i
R
o
c
aoc
aIL
c
E cc
y
u
Wa
oo
Q
a S
y¢
'�
v
d
� W
is
L
+S'
+�
Z a�
L
i
Lnv=
O
O
p
N
•~
N
rn
lf1
l0
1�
d
v
6.5. INTERDEPARTMENTAL COLLABORATION
Implementation of a stormwater management program requires collaboration from multiple
City departments. The City is committed to both meeting compliance requirements and
deadlines of the NPDES permit and providing its citizens with adequate stormwater
management services. The stormwater management program is led by the City's Environmental
Compliance Coordinator in the Public Works Department. The Environmental Compliance
Coordinator works closely with other City departments and divisions, including the Public Works
Operations Division, Parks and Recreation, and Community and Economic Development, to
implement activities in the program areas of flood protection and water quality. Table 6-S
summarizes the roles and responsibilities of the various City departments and divisions.
Table 6-5. Interdepartmental Responsibilities.
Department Responsibilities
Public Works — • Overall stormwater management planning and NPDES permit compliance
CIP Engineering Division responsibilities
• Public education and outreach related to stormwater issues
• Public involvement and participation
• IDDE program management
• Review of plans for development, redevelopment, and construction sites
• Compliance with TMDLs established for water bodies in the City
• Annual reporting requirements associated with the NPDES permit
• Comprehensive Stormwater Management Plan development and implementation
• CIP project planning, design, and construction.
• Implement Stormwater Pollution Prevention Plan (SWPPP) at multiple facilities
• Update and implement stormwater regulations and design criteria
• Technical consultation for development projects
Public Works —
• Public education and outreach for homeowners and businesses
Operations Division
• Illicit discharge reporting and response
• Inspection of public and privately owned flow control and water quality BMPs
• O&M of City -owned stormwater infrastructure
• Pollution prevention in municipal operations
• Implement Stormwater Pollution Prevention Plan (SWPPP) at multiple facilities
Parks and Recreation
• Stocking pet waste bag dispensers in City parks
• Implement Stormwater Pollution Prevention Plan (SWPPP) at multiple facilities
Community and
• Review of plans for development, redevelopment, and construction sites
Economic Development
• Wetland and other critical areas issues
• Administers SEPA review of City CIP projects
• Floodplain management issues
It is recommended that the City departments and divisions meet on an annual basis to discuss
the interdepartmental roles and responsibilities and ensure the success of the City's stormwater
management program.
March 2023
(� HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
75
C.C. INTERAGENCY COLLABORATION
Collaboration with other permittees in Eastern Washington has been very beneficial to the City.
The Eastern Washington Stormwater Managers Group has been instrumental in guiding
development of the NPDES permit, directing stormwater related guidance manuals, and sharing
other valuable information. The group is currently involved in implementing stormwater
effectiveness studies and guiding the update of the Stormwater Management Manual for
Eastern Washington. Staff time spent on Interagency Collaboration is covered through existing
FTEs. The City of Pasco will continue to be an active member of the Eastern Washington
Stormwater Managers Group.
4 HERRERA
March 2023
76
City of Pasco Comprehensive Stormwater Management Plan — 2023
7. REFERENCES
Abatzoglou, J.T., D.E. Rupp, and P.W. Mote. 2014. Seasonal Climate Variability and Change in the
Pacific Northwest of the United States. Journal of Climate. 27:2125-2142.
AHBL and HDR. 2013. Eastern Washington Low Impact Development Guidance Manual.
Prepared for the Washington State Department of Ecology by AHBL, Inc. and HDR Engineering.
June.
Anchor QEA. 2014. Shoreline Inventory, Analysis, and Characterization Report. City of Pasco
Shoreline Master Program Update. Prepared for City of Pasco. October.
Barnett, T.P., J.C. Adam, and D.P. Lettenmaier. 2005. Potential Impacts of a Warming Climate on
Water Availability in Snow -Dominated Regions. Nature 438:303-309.
Caldwell, R.J., S. Gangopadhyay, J. Bountry, Y. Lai, and M.M. Elsner. 2013. Statistical Modeling of
Daily and Subdaily Stream Temperatures: Application to the Methow River Basin, Washington.
Water Resources Research 49:4346-4361.
CH2M Hill. 2014. Oregon Avenue (SR 397) Corridor Traffic Study and Design-Geotechnical
Report. Prepared for City of Pasco. April.
Dalton, M.M., P.W. Mote, and A.K. Snover. 2013. Climate Change in the Northwest: Implications
for our Landscapes, Waters, and Communities. Island Press, Washington, DC.
Elsner, M.M., L. Cuo, N. Voisin, J.S. Deems, A.F. Hamlet, J.A. Vano, K.E.B. Mickelson, S. Lee and
D.P. Lettenmaier. 2010. "Implications of 21 st Century Climate Change for the Hydrology of
Washington, State." Climatic Change 102:225-260.
Hamlet, A.F., M.M. Elsner, G.S. Mauger, S-Y. Lee, I. Tohver, and R.A. Norheim. 2013. An overview
of the Columbia Basin Climate Change Scenarios Project: Approach, methods, and summary of
key results. Atmosphere -Ocean 51(4):392-415.
ISAB. 2007. Climate Change Impacts on Columbia River Basin Fish and Wildlife. Climate Change
Report ISAB 2007-2. Independent Scientific Advisory Board, Portland, Oregon.
Kahle, S.C., Olsen, T.D., and D.S. Morgan. 2009. Scientific Investigations Map 3088. Geologic
Setting and Hydrogeologic Units of the Columba Plateau Regional Aquifer System, Washington,
Oregon, and Idaho. United States Geological Survey Groundwater Resources Program,
Kammerer, J.C. 1990. Largest Rivers in the United States. United States Geological Survey Water
Fact Sheet. USGS Water Resources Division, Virginia.
March 2023
* HERRERA
City of Pasco Comprehensive Stormwater Management Plan — 2023
77
NRCS. 2016. Soil Survey Staff, Natural Resources Conservation Service, United States
Department of Agriculture. Web Soil Survey. Accessed March 2016.
<http://websoilsurvey.nres.usda.gov/>.
Leppi, J.C., T.H. DeLuca, S.W. Harrar, and S.W. Running. 2011. Impacts of Climate Change on
August Stream Discharge in the Central -Rocky Mountains. Climatic Change 112: 997-1014.
NMFS. 2014. Impacts of Climate Change on Columbia River Salmon: A Review of the Scientific
Literature Published in 2013. Fish Ecology Division, Northwest Fisheries Science Center, National
Marine Fisheries Service. August.
OFM. 2017. Growth Management Act Population Projections for Counties: 2010 to 2040.
<https://ofm.wa.goy/washinaton-data -research/population-demograp hics population-
forecasts-and-projections/growth-management-act-county-Rrojections/growth-management-
act-population-projections-counties-2010-2040-0>.
Pasco, City of. 2014. Water Quality Report 2014. City of Pasco, Washington.
PWS ID#WA0664003. Pasco, Washington.
Pasco, City of. 2018. Land Capacity Analysis. City of Pasco, Washington. <htt s: www. asco-
wa. ov DocumentCenter iew 61799 A endix-C-Cit -of-Pasco-Land-Ca acit -Anal sis>.
Pasco, City of. 2020. Pasco Comprehensive Plan. City of Pasco, Washington. Pasco, Washington.
Pasco, City of. 2022. MS4 Annual Report 2022. City of Pasco, Washington. Pasco, Washington.
PBS. 2014. Pavement Design Report -Argent Road Rehabilitation and Widening. Pasco,
Washington. Prepared by PBS Engineers for City of Pasco, Washington. April.
Snover, A.K., G.S. Mauger, L.C.W. Binder, M. Krosby, and I. Tohver. 2013. Climate Change Impacts
and Adaptation in Washington State: Technical Summaries for Decision Makers. Climate Impacts
Group, University of Washington, Seattle.
USACE. 2016. McNary Dam and Lake Wallula. United States Army Corps of Engineers Walla
Walla District.
<htt www.nww.usace.arm .mil Missions Recreation McNa DamandLakeWallula.as x>.
USGS. 2016. Columbia River Basalt Group Stretches from Oregon to Idaho. United States
Geological Service Volcano Hazards Program, Cascades Volcano Observatory.
<http://voIcanoes.usas.aov/observatories/cvo/cvo columbia river basalt.html>.
I'::! FiERRERA
March 2023
78 City of Pasco Comprehensive Stormwater Management Plan — 2023
APPENDIX A
City of Pasco Stormwater Management (SWM)
Program Questionnaire
4 HERRERA
This page intentionally left blank
City of Pasco
Stormwater Management (SWM) Program
Questionnaire
Overall
1. What are the City's top issues with stormwater management?
2. What are the City's priorities for water quality and resource protection (what
resources or water bodies)?
3. What elements of the current SWM program/approach work well?
4. What elements of the current SWIM program/approach don't work well and what
changes are needed?
5. Are there any major roadblocks to execution of any current or upcoming SWM
program components?
May 24, 2022 1 Herrera Environmental Consultants
Staffing
6. Approximately how much staff time is allocated to SWM and stormwater capital
improvement projects (CIPs)? Is any of this work contracted out? If so, how much
of this work is contracted out?
Permit component
Staff time
Contractor
time
Public education and outreach
Public involvement and participation
IDDE
Construction site stormwater runoff control (including
site plan review and construction inspections)
Post -construction stormwater management for new
development and redevelopment
Municipal O&M
Compliance with TMDL requirements
Monitoring and assessment
Reporting requirements
Stormwater CIPs
May 24, 2022 2 Herrera Environmental Consultants
Public Participation (Education, Outreach, & Involvement)
7. Which programs and stewardship opportunities are most successful? Why do you
think that?
8. Which programs and stewardship opportunities are least successful? Why do you
think that?
9. What additional programs and stewardship opportunities is the City considering
for 2022 or beyond?
10. Is there a written plan that defines a public education and marketing strategy for
the overall SWM program?
11. What are the established stakeholder groups that the City consults with
regarding stormwater?
12. What opportunities exist for interjurisdictional cooperation?
13. What barriers exist to interjurisdictional cooperation?
14. How does the City solicit input and process comments on changes to the SWM
program?
May 24, 2022 3 Herrera Environmental Consultants
Illicit Discharge Detection and Elimination (IDDE)
15. Does the City stormwater system map have any known significant information gaps
or inaccuracies?
16. Is the City on track to complete mapping of all known connections from the MS4
to privately operated stormwater systems by August 1, 2023?
17. Does the City have a defined schema for infrastructure data stored in GIS or other
formats?
18. Describe the IDDE screening process.
a. What type of field screening methodologies do you use (i.e., catch
basin/manhole inspections, outfall inspections)?
b. How are field assessment activities tracked?
c. Are you on track to complete field assessing an average of 12% of the
MS4 each year?
19. Which staff/departments are required to attend IDDE training and identification?
Do you have different types of training for non SWM-staff?
May 24, 2022 4 Herrera Environmental Consultants
20. Are there general areas in the city where illicit discharges are perceived as a
greater problem?
21. What land uses and industries are viewed as priority sources for stormwater
pollution in the City?
22. How are illicit discharges to receiving waters (e.g., discharges that go directly to
the river versus to the stormwater conveyance system) addressed?
23. Does the City have the enforcement structure needed to address pollutants
discharged directly to receiving waters (not through MS4)?
24. What is going well with the City's IDDE program? What challenges are you
facing?
May 24, 2022 5 Herrera Environmental Consultants
Construction Site Stormwater Runoff Control
Stormwater Plan Review
25. How would you describe the type and quantity of development that has occurred
in the City in the past 5 years (the more detail the better)? Are there any places
where a lot of redevelopment is occurring that may need to be the focus of our
field work?
26. What type of development is expected in the next 10 years?
27. Describe the City's stormwater plan review process.
28. How does the City verify stormwater BMP/facility sizing during plan review (e.g.,
modeling, calculations, professional judgment)?
29. Has the City developed checklists or other tools (e.g., sizing tables) to help
reviewers with the stormwater plan review process? If so, what are they? Would
reviewers benefit from additional checklists/tools that could increase efficiency?
30. Are there any perceived threats to groundwater quality or quantity or stream flow
requirements that should be evaluated as part of this project?
May 24, 2022
Herrera Environmental Consultants
31. The 2020 Annual Report noted that there were no new annexations,
incorporations, or boundary changes during the reporting period. Are there
expected annexations in the next few years? And if so, how do you expect that to
influence staffing?
32. What challenges do Endangered Species Act (ESA) considerations, shoreline
management, Growth Management Act, and critical areas create for SWM in the
City?
33. Have you had any challenges in implementing the 2004 or 2019 Stormwater
Management Manual for Eastern Washington (Ecology manual) based on the
stormwater site plans that you have received and reviewed?
Construction Stormwater Site Inspections
34. Who inspects permitted development sites prior to, during, and post -
construction?
35. Are erosion and sediment control measures usually implemented correctly?
36. What is the enforcement process when they are not implemented correctly?
37. What type of tracking/record keeping is performed for inspections (e.g., hard copy
inspection forms, electronic forms, notes)?
May 24, 2022 7 Herrera Environmental Consultants
Municipal O&M
Private Structural BMP Inspections
38. What type of tracking/recordkeeping is performed for structural BMP inspections
(e.g., hard copy inspection forms, electronic forms, notes)
39. Does the City provide any education and outreach activities or materials to
improve maintenance of privately -maintained structural BMPs?
If yes, what type of activities/materials have been developed and have they been
effective?
❑ Handouts
❑ Workshops
❑ Internet resources
40. In what cases would your staff enter private property and perform corrective
work on privately -maintained structural BMPs (if ever)?
41. How does the City deal with defunct homeowners' associations (HOAs) or
difficulties identifying the responsible party of a privately -maintained structural
BMP that requires inspection and maintenance?
42. What standards do you use for inspection and maintenance of older stormwater
BMPs (e.g., BMPs permitted or constructed prior to implementation of the 2004
Ecology manual or the 2019 Ecology manual)?
May 24, 2022 8 Herrera Environmental Consultants
43. Does the City have any plans for changing how O&M of privately -maintained
structural BMPs is managed in the future?
44. Are there any known privately owned stormwater conveyance pipes in the City
that receive stormwater from the public system?
a. If yes, do these lines ever cause problems and how does the City address
them?
45. Does the City have privately owned streets with privately owned stormwater
systems and do these create any issues for SWM?
O&M of City -owned Structural BMPs
46. How many people are on your stormwater O&M crew?
47. Do your stormwater O&M staff that are funded by the SWM utility support
Streets or other utilities some of the time?
48. What other crews support stormwater O&M work (for example, during storm
response activities)?
49. Does the City maintain a list of maintenance problem locations (e.g., places that
O&M staff check on during and/or following major storms — aka Spot Check
List)?
May 24, 2022 9 Herrera Environmental Consultants
50. How often do O&M staff perform spot-checks?
51. How frequently are City -owned stormwater facilities (e.g., ponds, vaults, pipes)
inspected?
52. How do you track facility inspections?
53. Is electronic data collection (e.g., using a cell phone, tablet, or laptop) used for
O&M activities? Has this been successful? What challenges are you facing?
54. Are there any shared regional stormwater facilities?
55. Does the City currently have a Stormwater Pollution Prevention Plan (SWPPP) for
any of its facilities? If so:
a. Which ones?
b. How much staff time is used in implementing these SWPPP(s)?
c. Have any revisions been made to the SWPPP(s) since they were
developed?
56. Are written standard operating procedures (SOPS) in place for O&M staff for
preventing stormwater pollution outside of City -owned facilities?
May 24, 2022 10 Herrera Environmental Consultants
57. Describe the City's current catch basin inspection schedule/program.
58. What is the total number of City -owned catch basins? How many catch basins are
inspected annually? How many catch basins are cleaned annually?
59. What is the total number of City -owned stormwater BMPs/facilities (e.g., drywells,
ponds, etc.)? How many stormwater BMPs/facilities are inspected annually? How
many stormwater BMPs/facilities are maintained annually?
60. What is the total number of City -owned culverts? How many culverts are
inspected annually? How many culverts are maintained annually?
61. How many miles of open ditches are located in the City? How many miles of
stormwater system pipe are located in the City?
62. Does the City currently have the needed vehicles and equipment to maintain the
stormwater system?
Stormwater Asset Management
63. Does the City have an active asset management program for its owned or
operated stormwater infrastructure to determine lifespan and repair/replacement
needs?
May 24, 2022 11 Herrera Environmental Consultants
a. What types of assets or structures are regularly evaluated and at what
frequency? (complete the following table)
Asset/Structure
Currently
Evaluated?
(Yes/No)
Frequency of
Current Evaluation
Preferred
Frequency for
Future Evaluation
Aboveground assets
Underground vaults, tanks
Underground pipes
b. If CCTV inspection of pipes is planned in the future, has the City calculated
how many years it will take to inspect the entire system? Are the necessary
staff to support this program included in current staffing levels?
64. What asset management software do you currently use or are you interested in
using?
a. How long have you been using this software?
b. What do you like and dislike about this software?
c. Is there a mobile application for conducting inspections that is linked to
this software? Was it provided by the software developer, developed in-
house, or developed by a consultant?
May 24, 2022 12 Herrera Environmental Consultants
Capital Project Design/Project Management
65. What is the status of your existing stormwater CIP projects?
66. Are there any major roadblocks to execution of any outstanding projects?
67. Briefly describe any known existing surface water/stormwater problems that are
not addressed by existing defined CIPs? Please describe any solutions that have
been put forward for addressing the issue.
Wrap-up
68. Is there anything else that you do related to stormwater that we didn't ask about?
May 24, 2022
13
Herrera Environmental Consultants
This page intentionally left blank
APPENDIX B
Stormwater Management Program Evaluation
and Recommended activities
Oj HERRERA
This page intentionally left blank
i
n
d
a >'
m a`+
a 3
o
v m
m
e
m U
E
cpi
m � o
W '
6 U
a °
3 �
a—
m 3 > a
a W
w p ui
6 a IL c
d Z !7
Z
E _
y m m
Im
SoEL 0 u m m mo L Fm
c c !E o� '3 v tL
m
`y rn o a as v c y g c 3 �i E c
E o p y 9 N C U O
Rmg'v U £ t LE0 ��m m 'o
`mdo.d m E $ U m=a =Hm 10 Tc'
V' m�aoo g ` m Ee` 3=S m o�w
s >_� m a 1 �5 Ewa �16 �6
> >. 0 o m e °. W c W 3 r ` `� o E m a° o
vt�«wv�c v 'g oy�+
O oEWgms W m °c LvEn
0 .tm.E1 w� m a ° a a 3'c> a3m2 °cLic rm. Rm-r
S.
R C C N
d a IViv`�»v 4� E cm'$ «'u �H tEm c mEm m
r 15 mo3 `o Ecin o m
�a! fu lNm6 CWOof�ER-ac cNY'NE UWm-NW
'3m vN3, urb
Cm
mmmm c°y rnW . o
Y« .:0. w °
EaE« Imo 0
Q' - E c u o ur �' 3 n
m° L C t m C W C m U O N = o
U .`" m3 L .. c°i c m c� v E2 > L.
y c Edv m z .. C7 u m 3 m m'v °c c? o w 'o 06>2 o
4pc�mW ra s c o 3€ o 33 W `m Evv9 -"d
oO o- a °'
> c
m W d°E c
E L li 2 v o c ci m in m m W", .� m N t 3 «
°W m ymj >. N W N '° W Eqq F .L.. N o° L $ 2 W V C C m« E W x W
Im-£c-mE0 a' m y p ie� m i ioc a 3 w° u W cc occaci .5 3�$aO W 3
0
3- 2�0
`0Wmy€o .E° yo°°�c
o7 f2Em 'r om mEom
o
Nmrn`omm=o co
gccmmc€ aE0 -4 c
L o WpNo;
o eW
i_ mrnpcW `«3RLrm-urm>m c s.=. kQ,�N�mQ'E'
tm5iW
a mo�Em W�
72E.-o�00m0 W8.=��NE Y
wc
oZj
V L li oo. E o o o o o m` o o¢ �' y E vo D° o o v o ¢ o
_ m H
m
>
a 16 N t0 2p) N
m i d E- m o € o,E E. a E
E Am « ES
aam Ea E 'E > @ c Qv
cr Q m w oo m a c
W W w
d ° m m
E c g O1 � Ec w m m c c m umi
'o rnL y-'§ c m vo� im 6-2.
C� N'C C urn E
° ccu EL our
W �m.Wm.o aom�mam3
H
° � n" �L o ?
E t Ed-- my E m y ma 5 c 3
3 y o��0 m;E m',7,' �
F a- 3v _o
> m
Oc cQo>
c f C, o w
W --
c o
o w
5 W W
m m
a N
y
cLi
m
c
.j U 9 a
x
U Q
m
L yy
c
Y w
QI O n l;
'off ao
O
io
O L p m 0
Wpm
rm cd
E dm L°9 umi
v x
°cw mw
ay
yo 'c3
m Qj
O m Y
O E 7 C
d @ m
a dm0�
oo
w E
a�OEp cE
=9 'co
e
d$
w y m J y L
m C€
°
U o
m$ t V
ro
E a ::
.0
$`
m
n c c cyS iii
_ ayi m N
0
ON
C
_
E
10 y cLi amcc i
E3v
3y•E� �
m p
r= Em>
am m �'�m
�
Om�
p p
C
A3
L n C U m w C
w y N
O Y
r' rm
G> WQ
V O
3 0
o f
E ap
m 3 m a��
�
J? � dE �
y�aJ
oEa
Pami
CcH
W 3 O?
O100
D7 312
V T m Q N ID
E
1
m U
C
ON y
" N y O g O
-E -_ Y
C1
Y n 0
m 0 < C J C J a O
m N U N Q w p LL m U
a m W
K 6 L
U w m U
0 W L w ?i W
m
o ❑ cT m
i
�
A
IE
o
N
b
'E p
o H U
O
_ m m £
o a L
y
N
m O E
w
O
d n w m 1
o m
d ng �
m
m W m m
«
y w
a N L
p
K
02
N
q
W
m
; O
in ro€ m e
W
•
•'
tp 1.0 p L «
� O C C
<
o E
m Uy
d
r
rn . m m
� - n
b�N m�
Ci
m ro v �i 3 N .Z
P
CE
L
i t s m J m
O O C m
O
w
3 .°n is N E m
m N N W y L• J O �p
mO1 OI N 'V Z W m v
M
C
a W �z� 3 cwi0 v
a? r o
n�2 o a_O I w
a O
C
c N w m 0 =
E C C
r .0 O W m t O m O
m = F
0
€ a`
N
3
C y 0
t t €
y
U
o o F p C0 m
C
F W • • 10
C
e
�rnib =$ayi m E$
d
m
1!°m O0w w LLoy
w `-mLU
A
E
�
�w 'O m m 220
i'.l C > C
ama_ a
F.
•?
aoA w E o$y
V m 3 C O) 0•t N E
C
U 4i
N N O) N N= L C @5 N
o w
3 o m m 9 E n o= E
_
n- N N
d
c 6 U a O N C O
C .p- m a y 0 ti m 'p c
w m
E
dmN�3°n��mwmo`m
� m
O m C ... p E o y 4' N
` y
c a> E p w J m p
a� �i'LL cRU H dv f-L m
m o m
O
t
00
Om.
W
d
0
d
M
V
W
Q
d
V
d
E
E
ce
C7
C
m
C
V
u'
F
O
m
c
a H
m n
L 9
W
i CTo
j O
°
d w N
9p N N
W
m a >
h
a s U V e E y
c
o rn 10
00 A � W U E
0 O ; C Q m y 2y O
o m
J Y m n>
�p E L
C c 3 O 2 W
j U 0
ja
C m V C C N 3
o W W v
mU V
vi
rn E
W6 mN co C
N
.?
m m c N
;
c
c m g a o
W
� Syy W
E o W s E y y
m o
rn CL
� A
m «m V
�a'SQ ?�Oc�OS
w
=md
V , , O'mo .
2
U `o o
c
W N
v p m O m Y
r y 2 N m C c U N
U U c E
m C E V j -E y > O d d E m
d E m m o ?' E n g
$ y m c 0 m 'y °
m
V N E �' d > m
C d y o o `m W m rn E =m E
O m m W N? 0 'm0 O C` W
€ a m 7 y v'm > >� j O
am NO mv cvV
C w y N j0 C m m y N
��pa—°m m3amcci a Wpm m
W j W>m M. .o comE 3a 3'b
E m€am`m -5mQ o
c�c 3 €�€�
_O -0« H O U u J co m N 2
y m V c Cp
8mWa
c
0
W
m
a
N
N
aci
u
E
c
m rn
2 E
m
V
m
?? rn
m m
W
_
° A
N U m O
m m
3° c W
s_
p N
o,
3
o
cia
2
C
joqpm
U p
a t
m
I
Ol L
° °
U yyyO N O O
v
G
E
c c
oa
O
U W N a
m
.0
W o-
3 W
20
:'a-mm
U$ c>
v=
m
m
w
m w N 0
c
m
v
E d W
a
N
E m
E° W c R
N
my
8C >m3
m
E
O
cm
�m
m�ZoF.€
v
a Q
E w
Q m m u m
D
O
m
2o
3 N
N
E
E2=
o
°umi
5m
n°m dim
«
O W
mT C
L>
rn 3
U) co
U y
rn L € d w
°
H co
O
m
H E
F w U) 0
fV
m
y
M
ti N N m
C - C W % O
a d m c p cp o
m '2 pcmymr�G
M M O O
C W N -.p O O
0
= c
TU W %9Qr'U m
EL c i.wj E
% 0
l0 N O -O % YI H •j
$VW r
Q
O W y F
`m
0v€cLi4t'-c-Om�m
� o
3mHvv'�m3.`a
C -
O
Y cD E CO O N
v m y ^
N m c n m ti a m «, « i a
d� o�rn �EcyE 2 v w o0 $' Jm0 2
IC G @
G T a
•Wr, G m r O O N Q« @ U O M .W -0'ap m u m^ @
3 p N r m - y N C OO y O V `p 2) C A «
ad orT3 c--00 € EV �p cmi Na y 0`o m
O C C y T@ 2 J%% a:E 'C « C a p t 6 d C d C
E W O. K O '.mp N O C O m C y W V
c��aU `o H� cc @ He W W a_v c.EnaEm �LE2,
If/ a OI d m C E Q C W •_ @ J p. L p Q O
c C O C l0 w Q 'O W d« J d 2 m O. W E@ C P% VI N d.
O O U W 3 0 00 3 U 6@ N jp iy O Q M IL O a= m L a d a J J 'O !! y
O aN p pd N
m 7e
m O • N • - =E M c
W W a a
ci cn of ci
m QO [L m
h C N N
m c
o
U
%
W
y O 6
ry T d ,
%
O
y
@
c H
m
C
%
�
� '(0 O
w
@
O L W O
'>
um
m
O I d
w
o
a
(L) c w
U
a
m
N = 0
%
S
p
0
3 00
E
m
> E -
'E160
%
OMA
a
vJmr� > EE
«
d
U O W
-0 Ow
d
T
m
d y a ♦- N O G m
%
Z U m
m J
m
yy .O W O C m 0 0
om
E10
dr'U0`omU Ua
m o'dE
Enad$aav
u
U
O V w>
C
W
c w 5
a a
ci ci
m m
(Nq N
m C d
O � U OL..
N
pyp m
U y
d N m o U
> m
U O.
E a =r ti o,v m d€
c Elul
a m
manic mE"€�
0 o a ? O m 'oN- s
m L .. A
T °?
C �' O
m c as m- v, 'g m
c d
C p P� (n N N C ° 'n CO O
EO O
CG'C
m F G m
O d �' �
a
m
E
y d 0
m o
o m c
y
E w
p
15 o:9
t 55
32 O w G m
c O
m Uo OOup
C N
m 1
'mom q `0mo mm0wv-
C
3 m E
A
U V p�f >
L_
Q
m O O d _U N y
a Y 3 E$ N N I�0 Gpp E
V
C
L U Vi m N N
m a a
N Ol y m
W
N 'm`- c m L O W y 0 >> y o
d 6 N
U.G N c o m `m
¢ 3 W U
C
A
d
A
O
O
0
— u
~
0
m O
c a
d
� a
d
A m
�• U
y
3
.c
C
�
O
3 y
bi
U m
m c
a
om
N
.$
Q
<§
c U � •o
c Ro a
z u
d
a m m
K.
{O�
Na
O
.m O a `.
oi
3 c
01
C
c « c 6
S+ m LD m y d N
07 1�0 O
C
C N N 4J C G
P C m
L
U n C$ a
m �o 0
p U
E
t
U
m Q
'✓ my
N�
2'0J� Loa'
incn
v
d
Ia a il.a` w
C
� m m
��OJ
O
E
cc,Z• c�xE�ic c m._
e5m W�Oo
Ia0
F-
•c
me V R y E 10 m m c
mwv m0m.0 �am �=
m 'EtL n ui I m o
m`L' m�cf
m
ayo a�`mE mm m d�
m m c v LM
vc`c m °moL v Foa
EiE
•�'
C UU 'G @ G> r m y
A C C m`
0.0 d m N V L
UU y
C c
d
N y m O
QQ�� pCp m G a G d a
O to;. U a Oi J
LO N O p N y� a
C m d U p1 pG U a
O �j Ni Q y y L O U L y
` �. >>
N
{�
GO
CS
CGan Rm
y
C>A
VmN
awd
O�E
C O
O ° m
cd�J aC
bmEP
ua
H
N a
U N J L' N 3 N m d r m N J
ui ._ ._ a ._ > 3 a
YI N L N R = cam L •� y
q N J J y y c3 !• m m c 3 L• T G U
a o.
a
y U`O E •C Ua a Wa 6S ¢ E$
O
3Uaa O D i _m �a € U`o�c
a�
Lu�
�r .0
d L ,U O O { > O LLm 'C1 d
U.
C
O
M P1
M
{d
a
m m
OR
m
y
U)
! !§
2 § f(
)12
)_
f0
®2k§
/
\
V
\
\
Ck
\
�!
k)\k �
m
77■/)
E
Cm
LU
—u \
0
�§ ;�
�
LLJ 0. E
!
§
)22
■
�
J«�
e
_
!,
> -
�
)i
\\k
%
}0
.E
k|
0/
k
-
� ■
k »
§
{ƒE
k
kvlo
"Go
cc °2
{E0—
(
)/k(
|
f �I l�
a§,
!
;
§
■ )2��
(
e /
a
'
kki�
(\//LLl
�)
k
I
§
�\
®f
;
�!!<.J;';,!
k2Za)!
d1ECC
)0
!
!$§%k£§
a0E/.
--�
aRa 000
$!]
22:5
10
■
....
r.
§ \${
§ a 2`|$wa�-
�$®§Td
« ;7k � k& |, �-
3 § /k®|f .mot 0
!.{;\|4) )2E a
/ )
§)§
%k f�!«°E! %/}\) ) §f
`�.){\/{§?�§�! §(k(
!)i ifft
|-!!=Bll22,a«Ea, .
■■E|Ew!§22°�;}a0¥;±2�
-■ate°�:!)�,,;l�@�;�!!
Lu Z5 etfE§a�■$7±[!2
;|�!«a�E�)!a-50a 0 0
e�#,B§JBr��£a�la■_&�
Is
cli
Co
'n
cc.ti o0. c
tm
C @
m
o ami E' ,mo15
o aci
c a
0 myE
0
@
E m N m `
w E E c
m C V
0 16
12 �-
o m m3 L° an d m e
a m
0
m e `o
9 m an°
a
I col
an d
E O
aU^
m
mU pOp
O .. it m '�O O O. C
N C N Y V
aoNma:g Ecz_@@
c t W El c Z` cmi m U u
m.o@�
W 0 c m
y
@$ @@ •0 o Y E
crNs�,:[...�3
0 E c c
o
cNz cgCOL
c m
m�
A c
E'W rnw
m t 0 ', N •� a m N C
U
M �' m N On
U b C 0
V
L E ;; -CC
O
y �+ c
� V m � w@@ C�
W$
c .a
i°=mod Qa�a�co
o$ moc
FEm¢�ac@ �mv!
m
3
m m
N
S Y
U
@ }j m
.9— T
N �C
m
m a
m
m
E '�imE
E
a c @
p w
c E
3
W
ALNO
N N@
O« 7.
O pC
O N
N C
6 C O
M.
'O
N
O
q
p U
m a N C
N mN
N
@ C@
N r
@ a `o
V m
m «
A m = �
O �
O
1J
C.. rn d
mm
s
Oi
A E
Y
V
>
pp C U
G
w
v > c
>mN
'0 � L
'C N lV
3 N
w
C@-
c y
C
m
rm+
r
m`-
0
Q
ke
L o�T
mm
.gym c$m3
-Qp
c N
E'E
a@
a 3 $ E
c�� c
r m
n m
_
c N m m
OR a �+ m
w
CL $�;
d
3 m m
oo�C
2: m g
y'> E z
>
G
@ U@E
4 0' N
m ZS >
0
Q
m
O N
omC
m
Ew
G acw m
y
wj 'c
U m
adE
N PI
C
C m Om H
a d aE>'vi
O 0«
0. E m
N
0.0
C
p m m .O
C
N w LL m. m
.E E
3 N m N m V m
N
C 0) j O d
a
Q? C
@
3
H a F
u El 30imm��?i°c'mc
c 3 3 c' a cmi
- '" m 9 m
o>E63a��-8o�cg
n n m
V
C o
C aN$o-Y N° 3
Ez I d ao tEm
mn>aE m mo!'am
m
own==2int)m
='a'.'=_>3
m-ocaCL- �u..'c_no.oL
nw
C
U 2 IL T cc r 0 0 0
0 0 0 20 O O
fA 0 0 O O
O 0
G
m8yy mmyN
H a H H E 3
C
g
N
m c
w m w
9 u
m
4'
$ c a T._ c 0 v o
o o E m
ma'0°
E
y Lm m m
cO'e
u W
o
m "
v@
c
cw
maNva
m.CrnCa;o
Ko`
m m
�cRrn'm
�m
aO
Euot.'wmn
OON 'CwE
;.o.
«mwcC
Ccm@mo
qmCO
O
Z'.cSym
...mEmN@-.-
ncv
'
oc
o TCElm&�
@c
o
S;•ep)
��y u
c Q y�3
iL6CO
0nC
m-
m=ouE
o
Nm
�oE
mc
E@
dE0 y
O� N
G m O O O� C C C m U .. C OI
C •� 0 0 C LL .p �j 0 0
8 R m p U A m
N
u
cm mm-o cv�oa�c'c 3 Z516
m mac
p w -ru 02 ec
® w c�_i g.'U m 0 m -c
a o�
E ._ t> 0 it o n o m o �. w Jn
m 9 U n H Z m Z H LL m y
y
4' c u Q E --
W O T = 6 q 'c 7 r
o'u
E=
c c'amc=0L om
�OQ3 mm�L c�CL
0
h
I �
m m
m
A.
N N
b
C
M C O
O W Fj
0 7
D «
IO W Co
m G tl
CO
_O
W W
«o N 3
E
m €
W
N O
V pOq
W
OV p
O
W O
v
W
vi
O N O
R
aNN
R
L O O
W
'U
yO N
=
q N W
R 0-q W
C M
a U O V
C a
W m
CD
So
m
o R
ao>UcE
a
a
R
rn
V Qav a
a0
Z
a
�
yh
q
W
5 a W
pw o
E 3 C
W O)
.` Of
O
'O O
V1
` m5Em
Y3�E
e
'
o
2
EvOm
0
m nV
o-
-.2
o'mcWj
d
Um
c m
O O
ws o
CcC
�
4..�
a
W J
.0c
'E
U
6w
A W
R Y
id
W
o W O'2
�Z 0
�'
� y o`E
«�
Nn
aU
n W
o m
��
aci ro 3
E 3=
V
m
oc 3o Wm
ON�'
d
o-$
ma
oaci
aaL
d
c
2 ENDE
> o �,
o>
L
qE
E>.a
O)
.W.. 6
�¢
.m.. �
gym.. C
C
0 E
0
C 'O
10,
�i Q
amid
z �:c2c
i`ov�
�g
v
>aci
> yad
Q c
O ui m a
° c o
c .c
a
coi E
v O D
'a 3aE
cm c0o o
Eu:aa
v`0
y!�
`W o
0 0
U
N
W
•+ O
E
'm0 '°
v
3 N
V 2 o
E m
3
U gw
y 'O
t
d
'
a
u o m
y W
N
fm
Z
p p« O �_
U Cm
'O rL.. W t
W v c
Q
C
E
VmV
O -,Ma ]
a
y U a y
45
m X 0
12
W
3e
W€
R� 0 C a
D
r E 0 V
0I
C
A c
a N
N O
W p cq
0
; G
C
c.
caw ac
3Em�
�m
5,
mvZo
U
$ m�a35
«
M:°cc,03:�
u aci to
C
W'g
aW V) 2
'mym
090
emL
7
E'cci
O
000
O
:E C
o�cO1a,
y .0
N
N
L3
>y ° OLn
d
E
«°a
yE
U
v
N
_wcn
a
O
0- $EO.
$
C
H •
w .
V
C Q
N
Cl d O
c (L
t
I.
N o v
O N UI
3;
>' J C� O O1
O c
N ° O E
rn N E
'ba
c
N
E
m c 20
W c W
m .m
W
W c E
m E c« V
W 3
$
N
a O m y
0 € O m 0
N o�
W E «O E H
L
C N m j O W
3.5.
W C
W
W
L
m a l0 «O
m
.0
~
_m
mE
p �'v W
N$a
'vi
0
0a3rn
€�
�GH3aai t'mzW
N m m U
°�� �n
X m E
�°rnm �
�W O N 2 r
U',-
O
>
U
Z.
Q
d.o
O� O' P W 'O
L« K
IL y m D J M. 0 a
4i L 0
N C C a 0 0 0
m
.m.
m a C O C a
y X U
]
a N D L L
ti m N V `W C m E m
O O r >>
W O �L c
L C U° d
Q t W 2 y R
O c.6
C a p
'O
C N
d
m >� yyj M :s
E O) W C d
O
Cp O= C Z. 'm0 N Cy C>
pCo m
U Q
E G c C
u y
« O 0 Z
a Q
m N
O W U a
10
m yyy
•p m a'U C W m d E
0
N U :Ol 2. C 0 £=>
N .0 U W V
0 C m
C 0 M
O
E 0 U C O y W N V N aW. C y N� N 0 C
6 N YDg 9 E W
'O m C >a R D
= C
y H R
N
mO� C L O 'O H N W N 9 IL C 9 Y C C y C
C W '-
'O 6 C a W C
U
O
W
U a Q 6 a
W .m- C a• •
O a
• C m tLm)
C 0 a c
W
C C t Q N.L.,
a C
D w 0
Q 0
u
W W Q O
W
p o
yO =E8n
• •
•
•
e
w��
O
o
I
N
.q
Z,
L
C
«
M
m
7 t0
` O t
C m m
t0 tC
V V
m m
d
U
00M c°i
rail cn
0
as
m E
U
L m
C
m
'>
of
N fi vi
L
N C Q
x
o
E
o
C
CL
U � X
d
C
E o U
`o
o'--aa
e�
«�
n
w
y
d N >
EEy
c
m 16 '° c
Lo
O w d? C
m
-:s
o£
Ti
d ova
m :e3
a
c c5
•� W
R
rn c v
c
m `
Q
C a
N IG 9s
G
C
C
L y O
•,
y
E
V O p
'W N
a
W
c c r
O y O
Y1 d
y
>
C
W
U a U v
U
U� s m
m
m
W
m L
3
'w
W L d w
o.c"s
°
0 %
s 0 u
m d
V
>
N
m so
14
IL
O-wm c43 oa
o
d U
m V X V y
L
aw L
V
d
a ° O
0 U
m
°OU D
.2.y
'pp
L>N, d d
0WLe
yt
O° O y C d
y
o
F
vi sd W 3
E
N�p��.=o.ydL
C
>
N
y
Y
Q
Q
•�•
m
Q d> 9 c E
T w d C N C D
�
m J N m c
c
p
p
C
a �L c$ �
wt°
dao °mma
w
ciE
q
W
`�«�a�`� �
3
a
0
E
> >�
S � Cp
Q 5 2 U
d II C O >O C m
m 0 'E V} W U O
C
C
E C
3 0 C
S m m m
D
O
3 a
m w
3
O m
y
3 II
7C
c
a'
W H U 00 W c �
w
U
9
w .Li S r
5. m U L
L
C C m 0 C E U
W m
A
m v m y v
3 ~ 0--, E% c
E
y
IT w
m E> L L
E
d, EI.
oaaa ° mm
m 2
N N 0@
r 0 C NO M 2LD �
d � w G
C
E op p�
E
°
OU
n ooc
U$w
g�c d
5.y
-G
O
d o nwz
IIadCmi
aLL¢
�5
a.
> v n 3
_
w o •m Z` a R_
W'Emm
75
W
Em
�
a u�om ac mwz'>
u-ami ;ecumi Ecm
C 10 N m m C 0.
C9amOi
CII Z'�cca: and
p E
E
'NC0Ucam+
LCac'.nrnW.
^L•mmj
O C
NdEUcm
a�WwEn
0 d L'D y
cUWWmC;6°
oaWO
F
X momO
O .
>
CL
cr
oui
.
cc
vG
m32
€da
v
ducc
-rnE >ac mg
o 2o° `o E- i
8W
aeE0Do�
$:E E o3 o
N .0�
.7�mOCg)
° . c
�
t
oIm
om
no
omd
ab
c*�£ E' E'
a
tG0m
h 3 $UU �ta�ai.v_cT
Ey
2c�-
9
�c''wuCmn
o vd>Nwmm�$wcU�Nrmaw
ywU2icm
E«E
0
U
NW �W
iGZ•'mGGm
o�c3
c°Om
y'3ECw
°
amYI
•j-mw
d
yTiO
m m
a C
oc
.gm>o
d
IIoLVu
y7E
3•>p
3 'N ,
.y
�a md�
dlm0
Om 'm 0,
d
y
C2OWQQ011
dd
•po aaEai Uwc
II'
m yo$
a«
cNd
bT C�m
yO aC ¢C
.w°..°. N
OTa WlQ
O
aw
ENd
Oa3
r�i
G
6CLLm«OiL)
O. 0 C O
N EU t4 • W • •
q S m t
SaEDO • •
C. C
Lam
O_
E
a
oo
e
m
a
ne
m
IN
co
10
A
a
0
i
d
Z
Q
d
r
C
G
E
Y
12
V
C
A
C
V
Yw U d mN O C O1
i a O a O m m d y C y «
K-�E$� �m v16d`Eo
C E0•2 0000
m y�a0 mc:EE
U o
im�uoo300
C«ma« UoLC ' C dp
d
m U 'O C ° C d s a C O C 0« E
•€ pi• m a cwt ao«mm f-p wmmmo'N L .O cy mac
a c o c oc., m as nE dccvi L'�tam €nd �"
•1 a N ?� m Y w G @ o. C E m O C m y d C Q° Lm p G
`oPo:o ••�op3 0 M2 `o=O d`oc m•m mo 0Em c� m0
~ 0Q m.E x._>, �$ .OE mmE mmao>� mcQm °yoy;
E� ° m mom` �0E eEoQ� c om°Ud oco�ov�co mOa<<
e c A� ad mc°i ma«aw n 0 me °orno•-«
U) 41 .2 m m 6v ao o._
Cc m a n > E 0 3 0>°£ a E z m c« i
p �QoQm UmLW OMS= a, 1 m`o0Yoa«Y��cm �So� �Ec
Qi Y m a Y cg `a n a
o a
W W
m d `o m
STD 3 l] n Em
O
�j O d d cC « d
a D U O C 0 m
cco m 3
« m C W w
y •>c m c c c U � 'mt
0) m U y
E d $
dcEEy ca dm o
'o«dmm 0� t c
y>o
3a o
E ;-O nE cram cdi
.d w m E 2
m;„'gym mN ow z a
m
yO m o a m N mp 7
2 om dE me >' o
y a E m t6 0 y C m =� C
Q o m a E a 0 pia T
✓i @ L N N 0 C m
y V> 0 0
C
.. W U S m m c 6
o
€o nm acLiro 3 �� Q'
m C O O m
o "
N c m 01 ; LL W. V O C C N
pi a m€ c cSp m d d b
m E 0.5 « = 6 x L d> o
=Ea9am3ay ,>o�y
.2ooLd, a�nv Wi' w m am
pcE Oo yU3a E
N m m w m O N t°D y N C V a a
Eom-i_0 i
p d L t d o u
m U 3 y .O m
O L E tV m N y d 'p > C
m L O
U m 0 U E U a r d' ,L„ Q
av-3`mEavaIgaEath
_r
c a 7J y 0 d C 1
— 10 � m E � a O 0 `YS
mma L"'£pp 'c-0 22 E,
m U Op C « J L E m an d
m E« m m A° N N
W3 mrom
N 9 E E y E—c m m c m m
V O O O a O Y @ E K N V 3 a
R N m C m t V
c O1 £ O .O .. m m
OLLJ
a 0 0 o a c R
` d2¢ m E
c E d 0m Z o- y c PY
O m C° d y U N m C 0 c N o
.0 p m y E_ m>
udcoo �vmE�m
d > « >
Cc a
1 mmOE av�mm mo•�coo
m o p
a°zWEm ,
y�
P
V
N
Y
6
O
Q a
N d
c r
y2i
> o J
d
L
n c z
€
H
�mQc 02o
`"
n
E N V N U
•N
m
o
pp
EO ;0;y U 0
j
>
z C
N
C
0
N
c m
E�m
'0
� m
m a�C m ma L
a2
d
E a
m m
o y— V
v
Q
Q y
g
t m E m
.00
0 a N m lm0 C
O
d> m C m
O L L LO m Zia
d T y m 3m 0
Q 9
m
E
m t y n
N... ,� w
m
D a m m S g
> n
a C
um,i m
a3N2 mE
Erm30a
,0 m�e
3S`o
m
mt...
O
n Lo?
L .mi•:
ad
m N. E
(` L m d i
E
-
_d
o rn:E
m v c 3
m~ n m NN N
n`E
v m 'p
3 B. 9
a; O
O m U N=
N
m,
O 0
2
U
E �S c adi
EQ
E
O m d'
3
o No c
U Q
cmi �tnS
W m
m o E
aoo.c_aaa;Ev�¢d
o mmZ
C E N
E
o wEE«_5 Ewa
N 8 A a L C O.
O U0 « N m �
`O ai3M.2 m m�umi3E_ T yq
_ ii
N o m v m=m, umi n v
w ...m CL9 y °? tt O
m
�mEm m�=Ny_U
O d d nL C m L t Q 0
3m�c '360.E~am
o.� uU;vcaEi 3€w
3
m Ea
m a Q E m n m K n
$ n
so U)i
a q
Y1 N
!t1 m
d w m
C C L
w c d o 0- m
m^ adm Oaf d0 �O>y dE
.Q p L L C m L T O O C m L} N
.�
nm 163m rp 'c� dEE E
k2 o �y
m 0 E L a n° m o a c� m m ` 0
c u Eoa mma mW^ ia3
o w �nc vm �m�bwE Eo
Yqq C L N = d r m N Q g U J 2 L
.� EYo�visi� 2oc �`,o o2mL ��
W mavv mN� o�n 2�cm c.P�� �t
m a c o o o c oor
12
COLom co vm 0n5 zi
c E E E
i
2
k
�
/
§
�
i
«
'o y
a t
d
= U J E
O
V
d U
E m p C
d 1 C
O
E
c
O
E E d
U E
£ E = d
o m
a w
a
a
o
>d U`o
m
S m
C
E
E.
rn as
ti
Ea
ai c d
a Q o 'N to
m
E
m m N=
d
>a E a
>
m W
N E
J T
W
mE-
>
N
to m n
U 0m w c
m
C
m
ydi
v
�p d
C C � N O
m= "O v a N G U 3
w
Q
N «3 W `d a Of jq y
O
m�p2
to
,= o d a d �yy N a
T O
U �'
d
`•'
a '� 0 W N ° N
� G
E2� 3T ammo
N. d U
=w°
O
N c.Um c-
o d 3 o c
s
o
tJ
m v m m m o
ma
Al A` cnn
r
tp my
N
m N
U =
� 10 w
N L m v
m
Em ~otm
O
mm=m�
a
d
> d = E 2 U
$
d 'd d
• !
ii a
.2a
U m 0 E G
=mom .06E0-5.iEi5
i N C
'ova
•C d
O N O. .L...
C m
•p �
mcc ��m ajEW
a d d d
nmia �
=
E
c E 3 m
m—la'vT
w Ed °
d
UdNC
3nc
c
{��7
oCSE`a°$a��;E
o~N
N
m E
a
E«mtc mm� vrd.m�
c3 m
> d W j C m`
0
N N 1
8=d d am$ E&
c d A E m c., o
3 m E
a?� mn3oY .'
IL CL
Vyg
CN€oa3
Nwf�J1
00 ems dh`:
NW N
Idea doa 2U3N'W"V
dmd
9
H n m H a m m G 3£
H K
C
i.
O N N r r 1
V c w d m C W a y d m O m
m-• m o o f m m,� E� = m m� 3� rn �> v« c
d m E o o m c n v `d ^ N= o m 'v c o.o cd.
a E O - E AL
q fah d m L = 2$ O d U V E a C N C y =p IL a w C. C d d
rn dTo-oZl fcva_Ni'Qd'. o.� o-o 6�o51pp0z
cr d O C > m«V m A O Q N E J— d y '"' `. O d j d t = d d=Ix :9
.0 3 d f0 L .d• m '_O Qc W O C H pC_p fpJpp d N d C a $ t6 O m c E
C E O C y d d d N C O Q Jp C E m a ° d. a A d m m a °
d .� J C U S. m m �- 3 d d y N a r X E T d) J G? d N (n _U m
D. o"mL._m yN EEc dEa ma tads mvmcoao E E vmNc q�t•N"o�mwo
o u, S c ° m 2. dW ELw 4)IL om�=��2� �� �t°naE v�t0«ate' °'o��a2.oc
E e �m v m'2mw m -TiQ 2m m'Av Lmvo m'oao� ,od o'�,v v00� uNiEmo�:° m�cm nc
N i c Q 3 a 'C3 .g N y m m R E m N o E c E d 'cam° c >c_ m a L 3 w ._ � 2 r� a min w m H E � N N C >K d N
v EmEc o d m �o m`oo`c E� NEQ codmo adoiv2�� Cdd'tOa Nuoi
W d C d d (n C' > a U E in ii O d E> 4 a E¢ v a¢ N :E a N Q$ 'v ¢ 'd d m ° o
a'-dm �9m
(L(L m¢ .
o -
c
0
m o L
N '@ cd
E u o to
C m m
d to tun
0
z
41
V
yr
Y
a
d
C
E
E
Y
a.
V
C
C
7
V
p Z o
c
V 2 m m Q
m go
pp :R m u y o a m 3 m o c m 3 ° m m
CI m 3 C
f' b 02m E=> r�U �PmwdwUrn
oa —>'30 oo mi2�wm'��a-
m ° c H c'1 n m a `o m
€ .0 ii' mac° E x c,fmc'->--o
a —u0U ° n _m W—
5 a m E m W o o y
o—=m o=m ao W �n�ao�LLd'w E E
m 09
m omw.o. c E m�
E cd—W NNYW-O aco£ �cd`•tE gym` O
E a Y W m a N m Fi C m° C 7 m W a N m m° m I
gi.2 z oma �IE
p9m«`c a>i Uai«Pi�Qc�2 vV mt�il aE LL$n�
E
F m , O
m
o -
c E
_ E
N
a` co
d
r
Yi
Q �
�
v
� v
d
£
O
v
'O
C
C
°
R
a
�
3
�
d
`
U
e
y
`�
Y
C
r
m
lC9 y 3 m y N D
Lm.. V O N y O. - N C
N � O N
O m O W m R
V •�
N(�
C m
.y.
d
-2 3~ C$e J O m C
0
`m O a vj -Y
`V `-
d N
L m
;«
l0 C
Imp
-R.
>` (n y O N 0 ._. 'O N 0
L_ n o E m y d N
G V C G �yQ� M $ ') E m
lO w .y-
C a N T tV Cp4 uJi N
..
C ` N
lL0 O N E
F 5
C C ,gym, V 1 R R L
U r^y C.O' L O U V a
Cpp R d R m J
'CL
.O G E
m
y O y O/ f' m �-_' °
m p y� E O C R m O m m
m
Uw
w m
C. 7;6 m
�
oA
v-p C
�omom
>N
m c
a
N
m O
Q
O
Qffi E
Cm
�
mo
Np
w d E
o
I-
x
_E
M
AG $ m
c w E 75
$ 0. mf0 ; vwL=oc QQ o w m-pmm$
10ToQmcm
yc arnmo
mcEm mc`c
a m vioc
m�myE
E
ync�
�mm3a
Ec�cuiV.Ea3
m od «3no Ol > ? O_
m��Epr
(n L) � >: � �, E_ E crS rn a%
m O N R m Z N
p�Yc a >, m m
a
N c E c
r
>,
r a a o a pp�1
m J U J m m y p
v.
m o$
'c W
v€
o��m9'Eywo 0 0
o fnya`o tnw to m�d35mnwo
Qayr-w owvam�a
mdyrndm€
m
p d R O J m j y
U¢2E 9L4D
Y m C
C �m
m
Fmv._0.
0
APPENDIX C
Project Summary Sheets and Cost Estimates
4 HERRERA
This page intentionally left blank
E
E
i
0
w
o r
t''
0
00
0)
O aL+
Y
O C y •O
y ar
O
a
7-0
E
3 w
n E c
°o
c
o
w
co`o
Co
O Y?
m
c
m
y
Y
L
Q
m
m a c c
u
ns
L
v_
`o °a
s
a`mi c
Y
a u 4 E
o
3
m •o
C
Y V
00
10 ? C C
j O
w
N
e .c o
0
30
a1
a c o
G
a+ u
a`+ 03 a �.
j
w
�n
O
m Y=
G
O—
0
O
a
C
Y
w aw
E
w
v
w m_
c
c
o
u';
u
w
oo a
'H
w
a
oa a 0
•.
o
_
i.
—
a-
t'
u
4'
G
O 0
u
C a>
,'
•x
0 �
p
C G m p
C
C
'
C
G.
>
O
>
E; 3
a
G
E c s
E
E
y v'
L
m
m
N
N
L a
x
a a°
upa
as �3
a
a3
a
Ln
rn
a
In
LA \
7 �
O 0
a d m
a
a
o
U E E
N
N
N
N
N
N
z
0
0
0
0
0
S
0
p0
g
r
C
C
C
O
O
G
A
u
O
O
ti
O
N
rn
O
N
m
0
rn
m
0'
V)
rep
O
00
m
O
m
rn
c
ao ;!
F ei
N
N
N
N
N
N
N
g0
SO
C
C
O
C
O
G
0
0
00
a
14
N
rn
10
C
M
M
C N
U U
N
N
N
N
N
N
N
3
0
0
0
o
0
0
0
0
0
o
O
0
G Do
d R
U1
0
U1
l!1
111
ll1
L!1
ad Y
C G
a)
Y V
O
U 6
v
8
S
S
$
S
o
"o
o
O
o
o
rn
o
�
0
0
�
Ln
� Y
N
N
r~•I
�"�
Q N
N
N
N
N
N
N
N
G
O
S
S
S
O
O
O
O
O
O
O
10
Ln
00 N
.N-I
N
N
Kr
V
NO
M
G
v N
N
N
N
N
N
N
N
d
oao,
Oi
oNo
O
0)
N
Ln
M
0
�•-�
N
�••1
NO
N
0 0
2 �
a,
a `
a
E Q m
z
Z
O
Z
z
O z
Z
z
O
Q
Z
W W
Z W
O
0 wC
1=
r
Q
>
c
Q
J
CL
W
Q W
W
a
C=
W
LL
Z
LL
OG 0
O cc
Q O
ccLL
J
J O
>
w
>
Z
W
w
o
o
Q
w
m
0
w
d>
z
Z
W Z
z Z
F
Q z>
w H
z
H
O
O
w W
W
F-
Z
Q
v~i
w
J
Z
Z
O
N w
m
o W
0 W
N
a1
.ti ¢
J
z
e`I J
Q 0
W C:
Ln J
N O
lC w=
O O
w
N
O
'1
4 LL
^ C.
w
1 z
-M
ko Z
rN-I
O
n
aci
E
0
E
0
m
E:
C
O
v
17
a
L
V
C
N
0
m
E
w
L
tw
c
tu
u
C
a!
w
This page intentionally left blank
Pasco
tiff �
City of Pasco
Capital Improvement Program
Project Summary Sheet
Name: 214/219 N Sycamore Ave infiltration
Need:
High Priority
Project Type:
Flood Mitigation
Estimated Cost (2022):
$1,100,000
Construction Costs:
$452,000
All Costs:
$221,000
Contingency:
$337,000
Page 1 of 1
PROBLEM SUMMARY
The existing drywell manages a contributing impervious area of 5.84 acres, and appears to be undersized for the drainage area. Frequent and severe flooding
impacts travel lanes and private yards, and presents a significant maintenance cost to the City.
PRIORITIZATION
Risk
Ranking
Frequency
High: Floods after every rain event.
Severity
High: Travel lanes and private yards flood.
Traffic Level
Low: Residential street.
Other Criteria
Project Efficiency: No Maintenance Level of Effort: High Mobility Benefit: No
Overall Ranking
IHIGH
PROJECT MAP
Franklin County
t
-a
f
Ill" .Y I +<—i-1 r�W�
IT
► J`j
�mN _�},i�`.,QR
E
to $'r� • r , 4+!�
r EST
City Of
7
AOA ST
EE I
grit I
Pasco
1 ' { z •7
iIf
Jd �� `f
Install new catch basins � a�
and infiltration systems
to manage runoff from
1'
this basin. See
t•
Note 1.'� ti r
EGE RGE St
Benton county
g�
, ,fe -
z 1.r
i ; _.7I #' I
t b• • Y
jF
'_{�r I l
Note 1. Conceptual �
ee.n W.rq
St —water Pipe O City 1.1.11.
Countour(]It) _ county9auno>Y
1 ,t r, •"'
,L cost estimate assumes
j.' 31 each, 20 ft long
Highway
o stop —ter Inlet
.. . w
Awiru sr I . ,
-
infiltration trenches,
infiltration
• Manhole
i
and an
r
rate of 2.5 inches per hour.
c 1
, Further facility sizing
0 tao 280 ago 560
'.
vI� and siting would be t
1 '' completed during design.
Feet
-
PROPOSED SOLUTION
Add to the existing infiltration system to manage the drainage basin. The conceptual design assumes (31) Type II catch basins, each connected to a 20-LF
typical infiltration trench. The trenches are sized to mitigate the 25-year, 24-hour storm event for 5.84 acres
of impervious surface, at an infiltration rate of 2.5
inches per hour. Further facility sizing and siting would be determined during design.
EXISTING CONDITIONS
Looking South from problem site
shows evidence of pondingat the
catch basin and in the travel lane, up
into private lawns and driveways. i
d:+
0
m
o
c
� Y d
'_
O
w c
p m d
3 d o
E t a
o
E
M v1 u
�
v �
V V V
0
d
N O
r N N n >
y
N ^
O
N C
L
� d
m jp
U
�2
aL
x C
d O
L
H
V
C
O C
C
O
O
G m
O '-
O
m
C
am
v
r
++
C
O
u
_}
U
W
N
m
O
U
'C
O
Y
a
Z
W
3
E
p
N
O
E v
EO
c
o
d
E C
L
m
C
+d+ N
M
w
d
a
d
C H
m
C
U)
d
a
>
a
u°
LU
c
c N
U
W
0
O
m
0 m
`o
K
d
pNi
o
p
c
x
a oiS
Z
J
W x
o00
O
o
O1
O
Ol
1
w
oopv0000
0
1,
o
R
N
60
Ln
01
00
w
O
ZO
O
O
000
O
o
O
0
O
000$�$
0
O
0
O
0
O
0
c
p
Z
LO
w
L•i
M
N
V
-ZM'
N
.-L
O
H
Le
a
6
W
N
N
Q
m
N
O
N
6
N
O
m"
o
N
M
LL
Z
W
z
Z
'
a
M
V
.1
ei
�-I
a -I
rl
oo
.�-1
W
O
c
u
o
o
e
N
N
N
N
'i
a
o
tOD
o
O
ClCi
O
.0
to
N
N
0
N
iry/L
N
N
N
= 4 a
W
1� ON
J
nJO
W
Ln
L!
OI
4 t
O
rl
LA
N N
?
Q
Y.
O
H
Z
x
�_
Nc
W
oo
G
x
N
W
N
~
Z
a
J
N
d
a
x
p
W
a
x
U
a`
=
x
Z
W
a
:3 Z
o
M
Z
W
co cr
a
J
u
Z
z
o
z
0
F
zc
O
W
d
C
m cmZ
O
O
l
0
Q
0
0
?C
J<
WQt
Jp~NFp
'ja
QmoCOLLO
=
W
cc
cN
U
J
ma
ZWUZCHC
N
'oRLL N N
Z
W
Z
O
W
WWZ
K
pL
ryZ
NQ
Z
Z_V`
OZ�w
m
?
>
XEL
Z
Zy
E
O
r
Z
D
Q
na3
CO0
cc
Z
In
W
d
WW
ccxK
Z
in
pC
U
U}V:ZZ
JaHO
C
c
d d
0>
n
L
w
u~pcWC
W
=
Z
K
U
O
WW
p=
>
Z
W
F
Z
W
d d 0
o O
0J U U Q a N
1-
K
H
D
x
0.
V1
7
to
u
s
Ou
u
a
N
Q
O
OJO
u
a
u
H
City of Pasco
Pd.S o Capital Improvement Program
Project Summary Sheet
iq I1
Name. 1801 N Commercial Ave infiltration
Need: High Priority
Project Type:
Flood Mitigation
Estimated Cost (2022):
$720,000
Construction Costs:
$276,000
Allied/Soft Costs:
$201,000
Contingency:
$239,000
Page I of 1
PROBLEM SUMMARY
The existing infiltration system receives runoff from a contributing impervious area of 3.10 acres. The existing system appears to be undersized for managing
this area. The runoff floods the travel lanes, which are heavily used by large trucks.
PRIORITIZATION
Risk
Ranking
Frequency
High: Floods after every rain event.
Severity
High: Travel lanes flood.
Traffic Level
Medium: Road services commercial properties; frequent large trucks.
Other Criteria
Project Efficiency: Yes
Imaintenance Level of Effort: Typical IMobility Benefit: No
Overall Ranking
HIGH
PROJECT MAP
Franklin County
1
I -
City of
s Pasco
I Install new catch basins and
infiltration systems to manage
`
'
runoff from this basin. See Note 1.
c
Benton County
rA
<:.� "c
Note I. Conceptual
RICH Rl—
0 aly
��g`.y`
01
�s cost estimate assumes
��`'�us
ca, t—Rnt _' county aou.e.,,
•)*4 s„
�s '+� 18 each, 20 ft long
SIWmwMn Inle!
r y 1,
MMERCIkL-A4E infiltration trenches,
Nanhnh
�� °Ao;`
and an Infiltration
r�,j y ►
rate of 2.0 Inches per hour.
�'S,2ToPM Further facility sizing
and siting would be
a tsn sao 570 760
completed during design.
Feet
s f — --
PROPOSED SOLUTION
Add to the existing infiltration system to manage the drainage basin.
The conceptual design assumes (18) Type II catch basins, each connected to a 20-LF
typical infiltration trench. The trenches are sized to mitigate the
25-year, 24-hour storm event for 3.10 acres of impervious surface, at an infiltration rate of 2.0
inches per hour. Further facility sizing and siting would be determined
during design.
EXISTING CONDITIONS
Looking Northwest from problem site
r
Looking Southeast from problem site
shows evidence of ponding at the curb,
I shows evidence of ponding at the
and potential tributary area from food
curb and potential drainage from
processing facility.
i
IERA
v
3
E
v
0
to
w
0
LL
LL
cc
6
M U
!
Q
'.1 d N
E
L
P, u
n
N N N U
w
N �
C
m
O
N C
L
L � %
}
i_+
M d
m �
U
�
N
x C
d O
L
N
C
—
O C
U
m 6
O •-
~
V Di
O_
W
L
c
c
O
U
d
O- 0.
K
W
C n
° E w
c d C
m E c
v u
C " d
4) p d
d c N
o. �o
c
n >
U
Z
W
�
N
O �
7
N C
O
o s
a2
z
D W 2
O
O
O
O
O
R
N
O
O
O
O
Q
O
O
O
O
,Q
Op
O
O
O
O
Z
Q
d+
N
O
U
O
vi
0
1-
0
V
0
V
1
Oi
l0
R
t0
N'
00
11
u1'
l0
�O'
o0
,O'
0
~
O
�
X
0
V
0
Vi
0
O
O
O
'-I
0
N
� q
O
O1
M
O
O
N
j
N
H
N
N
N
M
Vf
N
Vf
rl
L!
11
of
10
N
in
N
N
.--I
N
.--1
+A
N
Lf
N
V!
N
N
V}
LL
Z
W
W
0
p
M
00
000
.--�
C
Q
a
JQ
V O
o00
U
o
oe
°
00
N
N
a'i
00
0
t0LU
O
to
1A
o 4
V N LL
w
?
J
O
O Q
�N ci
y
3
a_
LL
O
F
Z
Hc
_�
�
W
CO
L
N
W
N
v/
2
O
p
VI
d
2
U
a`
=
z
=
-j
W
d
V
u
_O
Z
cc
W
ee
Q�
u
Z
Z
O
z
O
F-
w
r H
O
H
Q
ucc+
z
«
O N z
C c o
W
1
~
i
Q
Q
Q
J
L
N -Fu%°
0c
K
V
J
Z
H
O
Q
W
W
O
J
W
Q
m O p N LL p
Z
Z
Z
w
W
Z
w
N
N
90
Q
a
z
Z
0
p
N LL N LL N J
M c l� l0 ? li
J
O
W
W
O
W
w
Q
w
F
W
d
Q.
d
W
a
C7
Z
N
z
Q
r
m
D
U
ui m
n° v u' Z
Z
F
s
G>
w
w
a
z
o
¢
w
o
Ian
E E
d a, c m O Z
O
�'
°
a
F
O
Q
3
z
G
O
z
a
Vco
'^
uzi
d
Z Z
co
> N G d -N d d _�
0 H
V
Q
tl
O
ycZcj
Z
0
Vcf
0000
Q}
U
Z
K
U
0 >O
J
LL
Qc
L
W
G
2
W
0U
N�
W
W
H
W
f
J
W
C
G d
E y d d Ll G
0
a M L L IZ a O
0
Q
K
Q
O
yUj
W
J
1"
c
L
i
Q
O
S
O
z
O
h
F-
Q
W
Z
O
O
z
s
0
W
In
W
Z
O
J
Z
O
I.-
O
W
d d V
O 0 J U ii Q Q kn
c
L
F
OC
H
7
2
d
V1
�
In
U
OC
u
d
N
0
V
Q
V
F
City of Pasco
Name: 600 East A Street Infiltration Page 1 of 1
Ltrk"
Masco
lCapital Improvement Program
Need:
High Priority
Project Summary Sheet
Project Type:
Flood Mitigation
Estimated Cost (2022):
$320,000
Construction Costs:
$117,000
Allied/Soft Costs;
$94,000
Contingency:
$106,000
PROBLEM SUMMARY
The existing low spot receives runoff from 0.82 acres of impervious area. No stormwater infrastructure exists to manage this runoff. The water builds up in the
roadway and presents a traffic hazard and maintenance issue, with pedestrian impacts.
PRIORITIZATION
Risk
Ranking
Frequency
High: Floods after every rain event.
Severity
High: Travel lanes flood; pedestrian impacts.
Traffic Level
Medium: Roadway services 1,000 to 5,000 average vehicles per day.
Other Criteria
Project Efficiency: No Maintenance Level of Effort: Typical
iMobility Benefit: No
Overall Ranking
IHIGH
PROJECT MAP
Franklin County
VW
1
Install new catch
1.
y basins and infiltration
,Z City of
systems to manage runoff
Pasco
from this basin. See Nate 1.
rA 5T E-A51
Benton County
r
IF
' /.. ; • 1 I V I .
'
r
- _ __ _ _-- -- _ - _
,R�.
® out. Rivet
— stom,weterPip p cm Limn•
Note 1. Conceptual cost
C-ntour 12 ett -.7 county eou—y
"��
�. r i
i= estimate assumes 5 each,
Z 20 ft long infiltration
O storm"ter Irdet
�uno�
trenches, and an Infiltration
rate of 2.5 Inches
per hour. Further facility
r
sizing and siting would be
0 70 140 210 2e0
completed during design.
PROPOSED SOLUTION
Install infiltration infrastructure within the drainage basin, consisting of (5) Type II catch basins, each connected to a 20-LF typical infiltration trench. The
trenches are sized to mitigate the 25-year, 24-hour storm event from 0.82 acres of impervious surface, at an infiltration
rate of 2.5 inches per hour. Further
facility sizing and siting would be determined during design.
EXISTING CONDITIONS
Looking East from problem site
4 Looking
East from problem site shows evidence
shows evidence of ponding at
of ponding
at curb and in travel lane.
curb and in travel lane.
- tr
HER
ERA
Q
r�
M
y
:1�
z
L
a
LL
� C
N O
u a
ri E
rn 23
L
- N N
N =
E
N C
a
L`%
`m
N
K
C
C
K V
�
L
C
U
O
d
d N
m
` 0
o
n
o
a
m
w
c
O
O U
�
U
a
m
z
z
m
m
v
E pL
L r
O1
O £ C
7
a)
d
w L
c >
+ O
r U
_
V V
C C
0 T
O 0O
N C
N
Lao
Q
O
c
m_
m
a
z
x x
x
w x
in
o
O
O
O
0
O
O
O
0
O
0
p
00
o
0
0
0
0
0
po
O
0
0�p
0
0
Z
W
W
n
u1
000
VTN
C5
.N-i
01
O
VF
N
an
`�
N
a
�Y/}�N�
0
M
N
ti
a^ -I
0
lO
0
O
r1
0
O
N
0
O
a
0
0
a
O
N
Vf
VI
A.
an
V/of
NNHN4A
A
V1
a
f
z
0
,»
�.�,�.�.�..,c�.N,o�in.�
N
J
LL
Z
W U
O
V
O
O
UA G
cc
•C
r-I
N
eel
111
N
N
VT
N
N
y a
LLLU
Q
1-
r
0 Q
to N U
}
3
a_
Y.
O
z
W
W
u
=
N
'
W
H
V)
d
Z
O
Q
x
p
W
O
x
U
d
C
N =
z
ao
U
W
a
U
O
Inz
cc
W
d
Q
U
J
U
Z
0
Z
0
Z
0
H
Zcc
O
Z
W
O N Z
N C C
O<
C
1>
Q
Q
a
Q
J
O
Z
J
L
w
W
J
E
w
_O
42
>` D6 N C N ~
m 0 p N p
O
O
X
W¢W>
X
LL
Z
N
Z
}
Q_
I:J
Z
Q
ZZa
F
N N
y@y
O
zwJ
ww
p¢Op
2
zvLL
Cd•
r` Co L
-0 W
OZw
s%
>
w
x
aM
z
ZyZr
rOmOyWJn
tp
VmGO
uVi
m
0
Ia. Z
v�m0co0 Z
Z
OZ)a
I.-
�w
>
H;F:
Zw_zmHr
M0
O
a
0
W
a'UULL
ID
Vi
Q
a
WOpaCQaiz
'A
COG
0V(g
••
V
OP P
E
O
aQ�
O
N
w
Q
W
DO(0
U
O
ZCo
!
z
e
a.0
g
UJUUQ.Q Ln
s�
vi~
�
s
v�lH7j
O¢uw
pJh
City of Pasco Name: 6415 Burden Blvd Infiltration Page 1 of 1
"" Capital Improvement Program Need: High Priority
PdSCtJ
Project Summary Sheet Project Type: Flood Mitigation
Estimated Cost (2022): $330,000
Construction Costs: $110,000
Allied/Soft Costs: $108,000
Contingency: $109,000
PROBLEM SUMMARY
The existing infiltration system receives runoff from a contributing impervious area of 1.10 acres. The existing system appears to be undersized for managing
this area, and suffers from hard -to -maintain siltation. Runoff floods the travel lane at the Northeast corner of the intersection with Robert Wayne Drive. This is
a heavily trafficked commercial area, and flooding receives complaints from the public.
PRIORITIZATION
Risk
Ranking
Frequency
Medium: Floods several times per year.
Severity
High: Travel lanes flood; impacts to commercial area.
Traffic Level
High: Roadway services 20,000 to 30,000 average vehicles per day.
Other Criteria
Project Efficiency: No Maintenance Level of Effort: Typical Mobility Benefit: No
Overall Ranking
IHIGH
PROJECT MAP
Franklin County
_ 1 1 )
I
City of
Pasco
�77
- }, d
Install new catch basins r f ti�
and infiltration systems
` — —
'
to manage runoff from o 0
this basin. See Note 1. = 9- '
f r
Benton County
BURDEN BLVD
.. ......_ _ aRt "S 'L—,—
AN
Q Basin River
— Sto—ater Pipe City Lamta
Couniow(2 yt) _ Coenty Boundary
� Conceptual cost
... & Note
estimate assumes 5 each,
t
Rlc•r
o S10--ter inlet
• Manhole
FF f 20 ft long infiltration
i trenches, and an infiltration
• rate of 4.5 inches
per hour. Further facility
V
o so tso 2ao 320
sizing and siting would be
completed during design.
Feet
PROPOSED SOLUTION
Add to the existing infiltration system to manage the drainage basin. The conceptual design assumes (5) Type II catch basins, each connected to a 20-LF typical
infiltration trench. The trenches are sized to mitigate the 25-year, 24-hour storm event from 1.10 acres of impervious surface, at an infiltration rate of 4.5
inches per hour. Further facility sizing and siting would be determined during design.
EXISTING CONDITIONS
/
Looking North from problem site along f
Robert Wayne Dr shows evidence of t K.'
Looking East from the problem
site along Burden Blvd shows
ponding in the travel lane. r
evidence of ponding at curb.
ins..
I
1
HER
11RA
o
W
'
p�
o
2
d
d
O
1cc0
My G N
N
rl V N
N O
N
O
N^„
N L
U
�
C
N C
L
u d
p c
N
U
c
G
N
K 0
d
d
H
U �
C
C
H N
d
c m
p •N
u ti c
d d ;?
C
O Y U
r
U
a
? d
is m
a
s
z
W
v w o
.i
E W
cN y C
u
_
d -0
E c
d
d U C
N -
d
c T
L
a Q
to
2
c °
w u
y
u >
N
Zu
u C
CO T
uj
d
O
R
W
y
t; .� n .0
L L L
o
0o cw m_
a oz
0'
Z
2 2 2
w 2
a
z
o
0
0
o
CD
a
Lon
o
0
0
0$
o
0
0
0
coo$$$
00
Vl
t+1
N
N
�••I
N
a
r
0
N
0
•-I
O
eel
0
Lp
0
0
N
0
cc
co
O
LT
O
O
IMI
V?tn
t4
V/N
JA
4A
VT�H�
�N-1
V?ynN
LLO
e^i
N•{?N
VM!
J
LL
.-�
.-i
ati
.H
.-/
�
Ln
O
�
N
L••I
Q
fOrl
.N-I
.-i
W
J
0
N
m Q
p
e
o
u
e
N
N
N
.--I
V
o
O
W O �±
.0
H
N
N
N
N
VI
1Nh
N
'•i
N
� 4 a
LL
ZO
T
to
LL
N
LL
J
LL
J
a
W
J
�
n
J�
J
V1
of
O
�Nu
a
3
�
LL
a
Q
F
=
Z_
l7
N
,ti
LU
W
00
w
x
N
N
2
d
Lo
a
=
p
c W
d
S
U
z
W
a
o
m
Z
c
C
u
0
0
z
H
w
W
w
co
O N ZCC
N C C O
w
Q
a
Q
a
H
o
Z
J
rL
l7
w
W
J
E
YO QQ
1
W
F
w
coo 0 ccl LL p d
d V, CD N N J
J
Z
W
Z
O
Z
W
W
w_
W
Z
w
W
d
N
W
n
U
m
ac
L
Q
Z
z
k
zz
Oh
tp
V
N C n N LL
O V Z
Z
Q
CC
F
WU
F
L++
a
W
f-
W
d
d
1'
y a
V-
Z
0
^2
a
a
1'
O
O}
c
d
G
v >, C
m 0 2
Q
Z
O
a
d
H
p�
O
Z
_
a
W
3
Z
a
O
a
U
Z
W
U
F
w
m
Z Z
d d U U .0 o N Q
N
u
Q
d
W
o
Q
tWn
m
7
T
2
U
oif
7
V
(7
2
rn
p p c
�g E y aoi ow a s
co
Q
a
u=
a>
O
0
0
P-
u
z
0
o
Z
W
Z
W
d d Ci
V 0J 0 0 Q Q 4A
2
P
aQ,
P..
7
2
as
LA
7
t;
U
C
8
a
L=ii
o
O
UQ
Q
U
O
City of Pasco
Name: 4416 Sedona Drive Infiltration Page 1 of 1
��CO
Capital Improvement Program
Need:
High Priority
Project Summary Sheet
Project Type:
Flood Mitigation
Estimated Cost (2022):
$350,000
'
lConstruction
Costs:
$118,000
Allied/Soft Costs:
$114,000
Contingency:
$116,000
PROBLEM SUMMARY
The existing infiltration system receives runoff from 2.03 acres of impervious area. The water frequently floods up to half the travel lane and sometimes more.
Stormwater in the travel lane can be pushed into driveways and garages by passing vehicles. This project was ranked by the listed criteria as Medium Priority,
but the larger drainage area pushed it to a higher priority.
PRIORITIZATION
Risk
Ranking
Frequency
Medium: Floods after almost every rain event.
Severity
High: Travel lanes, private driveways, and garages flood.
Traffic Level
Low: Residential street.
Other Criteria
Project Efficiency: No Maintenance Level of Effort: Medium Mobility Benefit: No
Overall Ranking
MEDIUM
PROJECT MAP
Franklin County
r
gff
} '
\ \ MESQUITE DR
.. soy coo yr
ai�-
., rrl Ai trig
I
. Y: rj City of
s Pasco
F � fit.
t r Install new catch basins -
- IF and Infiltration systems
to manage runoff from
Benton County
1 C
4 this basin. See Note 1. r
--
Slom,wabr Pipe Q CHy Llmita
Couatoar(2 rt{ _ countyeoundarr
Highway
. I + Y _ I \A -•��
■ a, T Note 1. Conceptual cost
�. estimate assumes 8 each,
Y 20 ft long infiltration
o stomwam'laser
-
• Manhole
-` - trenches, and an infiltration
rate of 4.5 inches
o per hour. Further facility
and would be
0 100 200 300 400
SAhirAANNALODp sizing siting
completed during design.
Feet
PROPOSED SOLUTION
Add to the existing infiltration system to manage the drainage basin. The conceptual design assumes (8) Type II catch basins, each connected to a 20-LF typical
infiltration trench. The trenches are sized to mitigate the 25-year, 24-hour storm event from 2.03 acres of impervious surface, at an infiltration rate of 4.5
inches per hour. Further facility sizing and siting would be determined during design.
EXISTING CONDITIONS
f Looking North from problem site
evidence of ponding around
[F—Lcoking South from problem site shows
ped driveways on West side of street
and low driveways on East side.
Ashows
I
d
HER
IERA
�
LU
w
k
s
\
0�
)
;«
\ \
\\
to u
\\ \ \
r
-
§\ -
_-
E
k\ / r
\§
2
■
)/oil
�\�k\^1^M
\
AA
0
)
§
$-----$LMU)00
&
>
K o
&Oa2Ln
c
mR�§]§§
■a°
■
§��
09�
2aLLLn
§2
i���q�E$»��m5
/���&
■
)
)
9
�
k�
■
i
f
k
§
�
)�
\
E §
z»=
E
(\zZz
$
LU
f
0g)
§u
°
k
E
)06 k
l±kk�°
a)
m
§
2
0
X—r4
���0U-\
Ez�<z§2m§k
tz3k
k�mP'a -
332-'r B
G>
tD2<
��;z
`§2§
Im
&$
&=&sae
z
zr�
pz=
o�
e<�wzzz«-
2��o«2
>��
-�G-�
■
■■
--
■�«=o=o
o
t$#��77
;u<
(���E�=tee§�az�c■�
rz�s»m2�
-
«
$f=
aoo §
E2�;�&
ag2
m�<u/�>rc§e8zB2b2z
zA
J
cL��
�L)-100 k
2Pcc
!a§�SwBEa$@828°
City Of Pasco
Name: 127 S Hugo Ave Infiltration Improvements Page 1 of 1
`
Capital Improvement Program
Need:
High Priority
Project Summary Sheet
Project Type:
Flood Mitigation
Estimated Cost (2022):
$380,000
lConstruction
Costs:
$142,000
Allied/Soft Costs:
$110,000
Contingency:
$126,000
PROBLEM SUMMARY
The existing infiltration system receives runoff from 1.39 acres of impervious area. Water overflows from the existing catch basin, flooding into the travel lane
and down into a private garage. This project was ranked as Medium Priority by the listed criteria,
but the significant impact to private property pushed it to a
higher priority.
PRIORITIZATION
Risk
Ranking
Frequency
Medium: Floods several times per year.
Severity
High: Travel lanes flood; significant impact to private garage.
Traffic Level
Low: Residential street.
Other Criteria
Project Efficiency: No IMaintenance Level of Effort: Typical Mobility Benefit: No
Overall Ranking
JIVIEDIUM
PROJECT MAP
Franklin County
-
I
LEWISS?
"
City Of
Pasco
_
�4' „�
T1;
1
Install new catch basins
and infiltration systems
to manage runoff from . r.
this basin. See Note 1. •
C_� � �• �
'+
I 4
Benton County
�
- Basin RWer
Strom wPips O anyumna
�
Note 1. Conceptual cost
f 1,,
Counto (zn) _ countyBcdndafy
Rio—,
-� +
i
, "litestimate assumes 8 each,
a 20 It long infiltration
o startnwabrinM,
0 M-hot.
�„
trenches, and an infiltration
el
Y rate of 2.5 Inches
per hour. further facility
o �s tsa 22s soo
N
sizing and siting would be
+' i completed during design.
Feet
I
---- —
PROPOSED SOLUTION
Add to the existing infiltration system to manage the drainage basin. The conceptual design assumes (8) Type II catch basins, each connected to a 20-LF typical
infiltration trench. The trenches are sized to mitigate the 25-year, 24-hour storm event from
1.39 acres of impervious surface, at an infiltration rate of 2.5
inches per hour. Further facility sizing and siting would be determined during design.
EXISTING CONDITIONS
Looking Southeast toward the
Looking South from the
problem site shows the garages
problem site shows down -
that are impacted by flooding.
sloping grades of driveways.
Ir_RA
�
k
�
\
\
\
2Ln
\\
\
� )
\.99
\ \ \
7�
- - -
)
-
$
kj
vo
E/
M
to
\ {
\\
mm
to
z
z
k \ k \
xm
§
ko
c5c5
_
-
to
©/3a&//&&$//&/a\inA4
q
k§-----`°§S°w-
B
LU
w 0
0§§�22rN4
-
§
»tee
-
2■9
§ww
�aLL§[
2�����§�$55�q
]
�
9
§
w
§
k
'
a
�
\
f
}§
2
/ u
)
IL
©
uI
0
2\/zz6
Z
i
w
p
e
z
§ug@g«
w
z
�
�
§
!
»<
/q
5
2
)
/dk ( R
§�/xzw
■§§k
ma
�q o^od K
o
�<
p�
kz<
«
-
�����'
3)2\2§
§§
§§�az§SG�/
E�zz�x
<L-
/
..�
$
_
u�£
>��
���0
3:
<0A
�zih
|%
,i72\33 0
�0
§»(§§¥§§§<
a
.
2§ ..
77===2` °
»ay ° P
§u
(�_cc
§o.
��-
z
$$j
�EZ()Q B
§»�u�«qr'a§/82a!§q§�zk
=2
wz
w
�u]66»a §
»a��8g8°
CLa.0
,r2§CIEXt;cc
City of Pasco
Capital Improvement Program
Project Summary Sheet
Name: W Sylvester Pipe Repair
Need:
High Priority
Project Type:
Pipe Repair
Estimated Cost (2022):
$930,000
Construction Costs:
$461,000
Allied/Soft Costs:
$154,000
Contingency:
$308,000
Page 1 of 1
PROBLEM SUMMARY
Three pipes in the conveyance system along or tributary to West Sylvester Street are deteriorated and are in need of replacement and/or repair. Damage
includes two holes, longitudinal and circumferential cracks, and heavy roots and debris.
PRIORITIZATION
Risk
Ranking
Pipe Size
High: Existing pipe diameters of 10 and 21 inches.
Pipe Defects
High: Holes, longitudinal and circumferential cracks, heavy roots and debris.
Traffic Level
High: Streets are downtown, servicing 5,000 to 10,000 average vehicles per day.
Other Criteria
Project Efficiency: No Maintenance Level of Effort: Typical iMobility Benefit: No
Overall Ranking
IHIGH
PROJECT MAP
Franklin County
T y'- ,>. * r'
or-CM
1 0
. rr City off,.
Pasco
a t�q Replace deteriorated pipes. See Note 1. ? f
�"'.0 c { i ,t
d c W NAON 5T � or
tr .r �f
r'r��r��► �
. r �� �t
►:,, %'
r_VY�.r
_ Ill�Y�•V, 5.
Benton CountyAll
DelarVoratetl River
• - F f -
wI:?viNasi - ,.� - -r� Note 1. Conceptual cost
�rY
5tormweter Npe 0 Clty omits`pNtN'y-
— scomwatrrlpa want ttanaa
y ry
. ►.5�- .
4
i'I �„ y ,'� c-r, estimate assumes 5 each .
Ari'wyq
' - - -V -�' --'i - � 4&1
countour,2 n)
Highway
f r•�� ,. nchtlia meter
,�{��,�-,' �,.� LT - ;yi ~'E _ malntenance holes, 500
O 5lormwater Inlet
e Manhole
i -+ iw • µ
. � .. � �� 5„o st �� linear feet of 21-Inch-
- r diameter storm sewer
* r�
,1 �A pipe, and 1,120 linear
Ir •
0 150 300 450 600
dw feet of 12-inch-diameter
A► r storm sewer pipe.
> - !* . fir!
Feet
y {
PROPOSED SOLUTION
Replace three pipes along North 10th Avenue and West Sylvester Street. The conceptual design assumes (5) 48-inch-diameter maintenance holes, 500linear
feet of 21-inch-diameter storm sewer pipe and 1,120 linear feet of 12-inch-diameter storm sewer pipe.
EXISTING CONDITIONS
Pe scs We.
Hole in pipe along N 10th Ave.
longitudinal crack in pipe along W Sylvester Sty ;
i
- ;r
21 84-
ti
r t
Et
ERA
I
W
OG
OL
W
m
v
rl
CN d
N
N
N
N
O
N
L
u
-0
C
(p
L
r`o
X
O/
U
W
O!
h
C
0
N
v
O
Y
U
2
O
c
u
K
Z
w
N
.0
c
m
a
m
N
y
ai
0
c
N
a�
L
0)
O
2
O
U
in
0
rn
0
tOo
0
O
0
O
o
NO
v
m
a
n
o
ONl
n
1
M
0
0
o
0
0
0
0
0
0
0
0$
0
0
0
0
0
0
V
n'i
'LnLd6Lrio
M
M
N
N
M
^m
M
�--�
~
�v000vaoo
N
-
In
n
of
O
M
W}
N
,c
N
a
t00
m
O
o
N
m.�
N
cn
N
N
W
a
�
a
W
O
00
N
00
U1
O
0
O
W O V
C
N
An
N
4a
LL
r O
}
N
N
O
Q
W
V
�
eN
Ln
ui
_
3NCi
N
N
J
0
p
LU
d
x
IL
c
� C
o
M
Z
0
WV'
u
0�
a_
W
Z
r
L Q
o
C ,
_¢
w
W
m N
CDC
W
a
Q
Q
O
D
J
c
L
E
N
T W m N C N W
V'
K
O
W
°C
Q
X
X
H
eq
N
Z
Q
Ma-'
W
m 0 o N
N0 O q
LL lN
VO
J
Zw
Z
Zd
w
WC
w
DW_ZN
m
Q
Z
m
O
N
�n CL
V W
CCUwF
d
ZZ
ZQ
N
yy
V
0 m
a C
ZCC
O
F-->
z
Ww
O
E E
? d T m o
3 v m 0 O
F-
O
Q
O
OC
d
F
O
3
w
W
a
J
O
D
o
Q
o
u
H
0
W
m
Z Z
d rd. a a U N N
N
U
>
O
W
(7
V7
to
0
0
OC
o�
0
C
t9
C
c
0) 07 C
m
n= V u `O O` CL 0-J
m
O
LL
0
U
< Q
`
W
Q
K
=
O
Z
Q
O
W
Z
w]
l7
W
V~1
W
J
F'
Q
W
a a U
Q O L L O. d O
O U J 0 U Q Q 4A
w
F-
O
w
W
F-
F-
O
x
CL
N
N
�n
OC
O
67
K
m
to
O
O
U
Q
C
U
O
i-
H
0
N