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4344 Resolution - 2023 Stormwater Management Plan
RESOLUTION 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? 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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