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HomeMy WebLinkAboutMemo - Mail Packet - 12/18/2018 - Memorandum From Matt Fater Re: Magnolia Street Outfall UpdateUtilities 700 Wood Street PO Box 580 Fort Collins, CO 80522 970.221-6700 970.221-6619 - fax fcgov.com MEMORANDUM DATE: December 5, 2018 TO: Mayor Troxell and Councilmembers THROUGH: Darin Atteberry, City Manager Jeff Mihelich, Deputy City Manager Kevin Gertig, Utilities Executive Director Theresa Connor, Deputy Director - Water Engineering and Field Operations FROM: Matt Fater, Civil Engineer III - Special Projects Manager RE: Magnolia Street Outfall Update Bottom Line The downtown area of Fort Collins faces significant flood risk. The Magnolia Street Outfall Project was identified in the 2003 Master Plan as a large diameter outfall to address a portion of the flooding. Staff has been working on alternative analysis, feasibility and cost estimating for the project. The project warrants a thorough process for public consensus and City Council direction given the significant magnitude of the project. Staff has developed a timeline for working towards City Council direction for the project in late 2020. Background Downtown Fort Collins was built prior to design standards for stormwater management and flood hazards. As a result, significant flood hazards due to intense rainfall exist in the downtown area including risk to homes, businesses, and roadways. The area has a history of repeated flooding including the storm event on May 22 nd of this year. Figure 1 identifies the 100-year floodplain for the Old Town Basin as well as the three major stormwater outfall projects and the Udall Water Quality Area. In 2003, the Stormwater Master Plan recommended a system of improvements in the Old Town Basin to address the flood risk including the Magnolia Street Outfall project. The system of recommended improvements is shown on Figure 1. The projects were originally conceptualized as large diameter storm sewer projects including extensions of the existing outfalls and an entirely new outfall along Magnolia Street. These master plan projects were conceptual approaches to address the flood hazard based on limited feasibility and alternative analysis. DocuSign Envelope ID: A75DB359-4BE1-4F6B-A7A5-71336E288538 Page 2 of 4 The 2017/2018 City budget included $1.5 Million in funding to begin design of the Magnolia Street Outfall project (Safe Community Offer 8.19). To date, approximately $400,000 has been spent conducting alternatives analysis, feasibility and cost estimating for the project. Project Goals The goal of the Magnolia Street Outfall project and the remaining downtown stormwater projects is to provide flood mitigation and treatment of stormwater runoff. These goals help reduce the social, environmental, and economic impacts associated with urban flooding such as public safety, property protection and water quality. In addition, the project seeks collaboration opportunities to enhance downtown and achieve additional City objectives. Feasibility Study A feasibility study was completed in 2017 & 2018 to confirm the viability of constructing the Magnolia Street Outfall project identified in the master plan. The technical work completed included: hydrologic modeling, pipe sizing, geotechnical investigations, and constructability analyses. The conceptual project includes 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 feasibility study estimated the project cost at $80 Million with a construction duration of over 3 years. A significant portion of the flood hazard in the downtown area would be addressed. However, flood hazards would remain until all remaining projects identified in Figure 1 are constructed. The feasibility analysis revealed the need to evaluate the Magnolia Street project and the remaining downtown projects as a system. This analysis, planned for early 2019, will determine if more cost-effective solutions exist for the entire downtown area. Alternative Analysis An alternative analysis was also conducted to determine if more cost-effective solutions could be identified and to evaluate the potential for multi-objective opportunities. While opportunities to reduce the overall cost were not identified, the analysis did identify potential approaches that could provide additional benefits to downtown such as: park space, access to nature and additional stormwater filtration. These approaches included regional and underground detention as well as repurposing portion of the public right of way for stormwater management. It was also identified that opportunities for streetscape enhancements exists with the conventional storm sewer option due to excavation and reconstruction of the street. While these approaches could provide additional benefits to the area, they also have significant challenges in terms of availability of vacant land and public concerns over reduction in street widths and potential loss of parking. For these reasons, these approaches would require significant public outreach and design work to further evaluate feasibility and community acceptance. DocuSign Envelope ID: A75DB359-4BE1-4F6B-A7A5-71336E288538 Page 3 of 4 Financial Analysis Rate stability is a key goal of the Utilities Financial Strategic Plan. Analysis was completed to determine the financial feasibility of the Stormwater Utility to fund a project of this magnitude along with other capital projects in the Financial Strategic Plan. Bonding will be required to generate enough capital to construct the project 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 such as this. Additional analysis will be needed to further confirm the financial feasibility of the project. Next Steps A project of this magnitude and expense requires significant analysis and community discussion. Staff will ultimately be seeking direction from Council on the project. The project team has developed a schedule to provide enough time for both additional technical analyses and community outreach. A critical milestone in the schedule is seeking direction from Council on the project by the end of 2020. If Council directs staff to move forward with the project, design and permitting would begin in 2021 with an estimated construction start of mid-2024. Activity 2019 2020 2021 2022 2023 2024 Additional Alternative Evaluation Community Outreach - Consensus Community Outreach - Construction Council Decision Design and Permitting Estimated Construction Start Staff will be scheduling Council work sessions in 2019 and 2020 to provide information on the project and seek Council guidance. The first of these work sessions is scheduled for March 26, 2019. DocuSign Envelope ID: A75DB359-4BE1-4F6B-A7A5-71336E288538 Page 4 of 4 Figure 1 – Old Town Basin Map DocuSign Envelope ID: A75DB359-4BE1-4F6B-A7A5-71336E288538