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HomeMy WebLinkAboutCOUNCIL - AGENDA ITEM - 09/17/2019 - DOWNTOWN STORMWATER IMPROVEMENT PLANDATE: STAFF: September 17, 2019 Matt Fater, Utilities Special Projects Manager Theresa Connor, Water Engineering Field Operations Mrg WORK SESSION ITEM City Council SUBJECT FOR DISCUSSION Downtown Stormwater Improvement Plan. EXECUTIVE SUMMARY The purpose of this item is to update City Council on future stormwater improvements in the downtown area. The downtown area is vulnerable to flood risk and pollution from stormwater runoff. The area was constructed over a century ago prior to design standards and criteria for stormwater management. As a result, there’s a lack of infrastructure to manage both stormwater quality and flood risks. The Downtown Stormwater Improvement Plan (DISP) is a system of stormwater improvements planned to address the stormwater quality and flood risks in the downtown area. The improvements include a combination of storm sewer and water quality enhancements to be implemented over the next 12-15 years. The specific projects in the plan will be recommended in future budget cycles for Council’s consideration. GENERAL DIRECTION SOUGHT AND SPECIFIC QUESTIONS TO BE ANSWERED 1. Does Council have any specific questions regarding the stormwater risks facing downtown Fort Collins? 2. Does Council have any questions on the approach to the Downtown Stormwater Improvement Plan? BACKGROUND / DISCUSSION Stormwater Utility The purpose of the Stormwater Utility is to provide flood damage reduction, enhance stormwater quality, and protect and restore riparian habitat. The City is divided into twelve stormwater basins for planning purposes. Each basin has a master plan that recommends improvements to meet these stormwater management goals. The challenges and opportunities within each basin are unique to that basin for several reasons, including topography, land use, available open space, and time frame of development. For example, basins developed before stormwater design criteria and floodplain regulations generally have a higher flood risk than basins developed after these criteria were adopted. The Stormwater Utility has invested over $100M in infrastructure based on the recommendations from each basin master plan. The flood mitigation improvements are designed to meet the 100- year storm protection standard. The 100-year storm is defined as a storm that has a 1% chance of being equaled or exceeded for a given location in any given year. Yet, significant improvements are still needed to provide all areas of Fort Collins with this same level of service. Old Town Basin The Old Town basin was primarily developed prior to design criteria and standards for stormwater management and flood hazards. As a result, flood hazards and pollution from urban stormwater runoff are significant risks to the community and the Cache la Poudre River. The 2003 Old Town Basin Master Plan identified a system of improvements to address these challenges including the Magnolia Street Outfall. Attachment 1 identifies the 100-year floodplain for the Old Town Basin as well as the existing major stormwater outfall projects and the Udall Water Quality Area. September 17, 2019 Page 2 The flood risk within the basin can be characterized as urban flooding due to the lack of stormwater infrastructure or a defined stream channel. During intense rainstorms, stormwater runoff is conveyed easterly along streets such as Maple, Magnolia and Myrtle. Flow depths in these streets can quickly reach 2-4 feet during these events exceeding curb heights and impacting adjacent homes and business. A recent study completed by ICON Engineering on behalf of the Utilities estimated nearly 550 structures would be damaged with an estimated damage cost of $83M to $92M as a result of the 100-year storm. Of these damaged structures, approximately half of these structures contain finished or partially finished basements that are particularly vulnerable to flood risk and pose a safety risk for people that may occupy these basements. This same study noted the repetitive nature of the flood risk with an estimated cost to the community of $151M to $165M over the next 50-years if no improvements are made. In addition, these conditions create economic, social, and environmental impacts such as public safety, business closures, traffic disruptions, and sewer overflows. Pollution from urban runoff is also a concern within the Old Town Basin. Sediments, fertilizers, oil, grease and other contaminants collect on the urban watershed. More frequent and less intense storms can mobilize these contaminants contributing to a water quality risk to the Cache la Poudre River. The City has constructed water quality treatment areas with past stormwater projects such as the Udall Water Quality Area. However, some areas of the Old Town basin lack sufficient treatment prior to discharge to the river. Magnolia Street Outfall The 2003 Old Town Basin Master Plan identified a system of projects necessary to address the remaining flood risk in the basin. The Magnolia Street Outfall was one of these projects. The conceptual project included storm sewers up to 120-inch diameter, extending from the Poudre River to Shields Street primarily within Magnolia Street. In addition, stormwater would be diverted to the Udall Water Quality area for treatment. The 2017/2018 City budget included $1.5 million in funding to begin design of the Magnolia Street Outfall (Safe Community Offer 8.19). Staff, with the assistance of Anderson Consulting Engineers, conducted a feasibility study for the project in 2018. The feasibility study estimated the project cost at $80 million with a construction duration of over three years. A significant portion of the flood hazard in the downtown area would be addressed. However, flood hazards would still exist until all remaining projects within the basin are constructed. The feasibility study revealed the need to evaluate the Magnolia Street project and the remaining downtown projects as a system of integrated improvements. The study also revealed the need to evaluate additional alternatives to determine if more cost- effective solutions exist for the entire downtown area. Downtown Stormwater Improvement Plan In the first half of 2019, staff, with the assistance of Anderson Consulting Engineers, completed a basin wide study to re-evaluate the recommendations of the 2003 Master Plan. The objectives of this study were to determine if a more cost-effective solution exists, as well as evaluate opportunities to meet other City objectives, such as park space, access to nature and additional stormwater filtration. Staff conducted workshops with other City departments to identify potential opportunities for collaboration. Alternative solutions for flood reduction such as regional detention, underground detention and repurposing portions of the right-of-way with smaller detention areas were all considered. However, these alternatives were determined to not be feasible due to cost, limited open space, and impacts to property access and parking. It was determined that opportunities for collaboration to meet other city objectives exists with a conventional storm sewer option due to excavation and reconstruction of the street. A system of five storm sewer projects was identified to most cost-effectively address the flood risk. Important advantages of this modified plan include less relative cost, reduced construction risk, greater utilization of existing stormwater infrastructure and outfalls, more opportunity for project phasing, and more opportunity for collaboration to meet other City objectives. The modified plan defined as the Downtown Stormwater Improvement Plan (DSIP) is shown on Attachment 2. The five projects within DSIP are large diameter storm sewers ranging in size from 36-inch to 102-inch diameter pipes designed to address the flood risk up to the 100-year storm. In addition to the storm sewers, the plan would provide storm water quality enhancements for the basin. The projects will require significant excavation and September 17, 2019 Page 3 reconstruction of several streets in the area. While this construction will be a significant disruption, several opportunities for collaboration have been identified that could leverage this construction to meet other City objectives. Some of these collaboration opportunities include streetscape, green infrastructure, bike/pedestrian improvements, Nature in the City projects, street maintenance, and aging utility infrastructure replacement. As each project moves forward with design, significant discussion and public outreach will be needed to identify which of these opportunities are appropriate and feasible for each block of the project. A cost estimate has been developed for the plan of improvements for both the flood reduction and water quality projects. Costs are considered conceptual due to the very early stage of design. Costs are presented below as a range to account for unknown conditions. The certainty of the cost estimates will increase as the design for each project moves forward. The design process will also evaluate options for minimizing construction risk and opportunities for cost savings. Conceptual Cost Storm Sewer Projects $130M - $150M Water Quality Enhancements $10M - $20M Total $140M - $170M *Costs are shown in 2020 dollars. The improvements would be implemented over several City budget cycles. A conceptual implementation plan was developed with the goal of minimizing construction impacts to the public as well as minimizing the financial impact on stormwater utility fees. The implementation considered factors such as flood risk reduction, utilization of existing infrastructure, constructability, and opportunities for collaboration. The implementation plan indicates the projects could be designed and constructed over the next 12-15 years, with the first of these projects proposed to start design as part of the 2021/22 budget and construction as part of the 2023/24 budget. This schedule assumes one project is under construction at a time to minimize impacts to the public. Financial Impacts Rate stability is a key goal of the Utilities Financial Strategic Plan. DSIP is part of the overall stormwater capital improvement plan. Analyses were completed to determine the financial feasibility of the Stormwater Utility to fund DISP along with other capital projects in the Financial Strategic Plan. Bonding will be required to generate enough capital to construct the projects within a reasonable timeframe. Preliminary analysis indicates this debt could be incurred with periodic rate increases of less than 3% given the Utility’s high debt capacity. The Stormwater Utility has significant, annual operating margin intended for capital improvements. Additional analysis will be needed to further confirm the financial feasibility of these improvements. Staff will be presenting the Utilities Financial Strategic Plan to the Council Finance Committee in November of this year. Any debt issuance will require approval from Council. Public Outreach Projects of this magnitude and expense require significant public outreach through planning, design and construction. Staff is committed to raising awareness of the proposed improvements as well as minimizing public impacts during construction. The outreach efforts are in the early stages with Water Board and Chamber of Commerce presentations already completed. Staff will be seeking other opportunities to present to community groups in the future. A public open house is planned for October 23, 2019 for the community. Also, a project website and informational video are being developed to raise awareness. Upon budget approval for each project, staff will begin project specific outreach efforts to seek feedback on street improvements and construction impacts. ATTACHMENTS 1. Old Town Basin Floodplain and Existing Outfalls (PDF) 2. Downtown Stormwater Improvement Plan (PDF) 3. Powerpoint presentation (PDF) 1 Downtown Stormwater Improvement Plan Matt Fater, Director – Civil Engineering, Utilities September 17, 2019 ATTACHMENT 3 Council Questions • Does Council have questions regarding the stormwater risks facing downtown Fort Collins? • Does Council have questions on the approach to the Downtown Stormwater Improvement Plan? Stormwater Policy Guidance Multi-dimensional criteria includes: • Water quality • Flood protection • Stream rehabilitation • Low impact development Overview • Downtown Stormwater Risks • Proposed Projects May 22, 2018 - 2 inches in 40 minutes June 24, 1992 - 2.5 inches in 30 minutes MASTER PLANS Project ID Conceptual Costs CAPITAL IMPROVEMENT PLAN Prioritization Levels of Service STRATEGIC FINANCIAL PLAN Rates Debt BUDGET OFFER Design FUTURE BUDGET OFFER Construction Capital Improvement Process Downtown Flooding • Urban flooding • High intensity rain • Lack of stormwater infrastructure • Topography is flat • Roadway ponding • Basement flooding Flood History Notable Floods to Date 1904,1933, 1938, 1951, 1977, 1983, 1988, 1992, 1997, 2009, 2017, 2018 Stormwater Quality Urban runoff Influent to Udall water quality area Floodplain and Existing Outfalls Oak Street Outfall – 90-inch tee Floodplain Removed Locust Street Outfall Downtown Stormwater Improvements Project(s) Benefits • Improve public safety • Avoid estimated $151M-$165M in flood damages • Address recurring street and intersection flooding • Improve stormwater quality to the Poudre River • Opportunities for green infrastructure • Remove regulatory floodplain Opportunities for Collaboration • Downtown Plan • Utility infrastructure replacement • Nature in the City • Streetscaping • Green infrastructure Cost Evolution COST CERTAINTY 100% 50% MASTER PLAN CONCEPT DESIGN CONSTRUCTION Cost Range Improvements Conceptual Cost Storm Sewer Improvements $130M - $150M Water Quality Improvements $10M - $20M Total Cost $140M - $170M MASTER PLANS Project ID Conceptual Costs CAPITAL IMPROVEMENT PLAN Prioritization Levels of Service STRATEGIC FINANCIAL PLAN Rates Debt BUDGET OFFER Design FUTURE BUDGET OFFER Construction Capital Improvement Process Implementation (Preliminary Construction Timeframes) 2024 - 2025 2026 - 2027 2028 - 2029 2031 - 2033 Jefferson Street project to be coordinated with future road improvements. Public Outreach • Overall Planning • Raise awareness • Community presentations • Website and video • Open House, Oct. 23 • Project • Project specific • Seek feedback on street improvements • Design and construction Council Questions • Does Council have questions regarding the stormwater risks facing downtown Fort Collins? • Does Council have questions on the approach to the Downtown Stormwater Improvement Plan?