Fargo-Moorhead Metropolitan Feasibility Study. Presentation for. City Engineers Association of Minnesota

Transcription

1 Fargo-Moorhead Metropolitan Feasibility Study Presentation for City Engineers Association of Minnesota January 28, 2010

2 Partners Corps of Engineers City of Fargo City of Moorhead Metropolitan Flood Management Committee 28 January

3 Why We Are Here Fargo-Moorhead area has significant flood risk Provide an overview of the process and outcomes of the Fargo-Moorhead Feasibility Study. Fargo-Moorhead Flood January

4 Funding and Costs Study costs are shared 50% federal, 50% non-federal Congress provides federal funds to the Corps Non-federal funding is provided by: City of Fargo, ND City of Moorhead, MN Buffalo-Red River Watershed District, MN Cass County, ND Estimated study cost: $8,000,000 Construction costs are shared 65% fed, 35% non-fed 28 January

5 Planning Process 1. Specify problems and opportunities. 2. Inventory and forecast conditions. 3. Formulate alternative plans. 4. Evaluate effects of alternative plans. 5. Compare alternative plans. 6. Select recommended plan. 28 January

6 Study Goals Develop a system to reduce regional flood risk Determine the Federal role in implementation Document findings in a Feasibility Report Recommend a project to Congress 28 January

7 Study Area Fargo-Moorhead metropolitan & surrounding area North: Harwood, ND & Kragnes, MN South: Oxbow, ND East: Dilworth, MN West: West Fargo, ND 28 January

8 Risk The 2009 flood was approximately a 125 year flood event. Successful flood fights lead to a false sense of security. It would be very difficult to fight floods larger than the 2009 flood. Failure of emergency levees would be catastrophic. Building of 2 nd St. Levee for 2009 Fargo-Moorhead Flood 28 January

9 Potential Depths of Inundation 28 January

10 Potential Depths of Inundation 28 January

11 Loss of Life Event Anticipated Event 98% Evacuation Unanticipated Event 0% Evacuation 1% Chance (100 yr) % Chance (500yr) *Assume Total Metro Population 202, January

12 STAGE, feet 50 Wetter Climate? Annual Peak Stages U.S.G.S Station FEMA 100-yr Event DATE FEMA 500-yr Event FEMA 100-yr Event FEMA 50-yr Event FEMA 10-yr Event Hydrologic record shows two periods: wet and dry 28 January

13 Wetter Climate? Panel of experts met to discuss hydrology Confirmed increasing trend in flood flow and frequency Cause of increasing trend is not known Red River has wet & dry cycles Currently in a wet cycle, but will eventually switch to dry cycle Recommendations Use non-standard hydrologic method to estimate future flows Assume that continued wet conditions are more likely than dry Actions taken Corps developed modified flow/frequency curves Will use modified curves for sensitivity analysis of selected plan 28 January

14 Alternatives No Action: Continue Emergency Measures Nonstructural measures Buyouts, Relocations, and Elevate Increase conveyance Diversion Channels Flood barriers Levees/Floodwalls Flood storage Large/Small 28 January

15 Initial Screening Criteria Effectiveness: Ability to provide acceptable level of flood risk management Environmental Effects: Effects on natural and cultural resources Social Effects: Effects on socio-economic resources Acceptability: Controversy and potential effects on community Implementability: Technical, social, legal or institutional issues Cost: The first cost of the project and operations and maintenance. Risk: The uncertainties surrounding the project Separable Mitigation: Is separable mitigation required and what is the cost Cost Effectiveness: Comparison of benefits and costs 28 January

16 Preliminary Screening Results Screened Alternatives Ranked by Net Benefits Avg Annual Net Benefits * Residual Damages * Alternative First Cost * MN Short Diversion 25K MN Short Diversion 35K 1, Levee 1% chance (100-year) MN Long Diversion 25K 1, MN Short Diversion 45K 1, MN Long Diversion 35K 1, B/C Ratio ND East Diversion 35K 1, ND West Diversion 35K 1, Levee 2% chance (50-year) ND West Diversion 45K 1, MN Long Diversion 45K 1, * In millions of dollars Note: Expected average annual damages without a project are $73.7 million. 28 January

17 Final Screening Alternatives Diversion Channels with Tie Back Levees Minnesota North Dakota 28 January

18 Detailed Analysis Working on Detailed Analysis MN Diversions with Tie Back Levee 4 separate plans (4 capacities: 20,000, 25,000, 30,000, and 35,000cfs) ND Diversion with Tie Back Levee 1 plan (2 capacities: 30,000 and 35,000cfs) 28 January

19 Preliminary Results Effects of Diversions STAGE at the FARGO GAGE 2% Chance 1% Chance 0.2% Chance (50-year) (100-year) (500-year) Existing Condition k Diversion k Diversion k Diversion Stage Impacts 27 Fargo Elm Street closed 30 Fargo 2nd Street Dike installed 31 Moorhead 1st Ave. North closed 32 First homes in Moorhead threatened 35 First homes in Fargo threatened Flood Record Stage 28 January

20 Stage in Feet Preliminary Results Effects of Diversions % Chance (50-year) 1% Chance (100-year) 0.2% Chance (500-year) Existing Condition 25k Diversion 35k Diversion 45k Diversion 28 January

21 Recreation Eligible Recreational Facilities Trails Hiking, Snowmobile, Cross Country Skiing, etc. Footbridges Fishing Facilities Picnic Shelters, Overlooks, Restrooms Camping facilities, picnic tables, grills, etc. Multiple Use Courts Interpretative Signs and Information 28 January

22 Path Forward Uncertainties: Natural Resource impacts (fish passage greater for ND diversion alignments) Additional project benefits Impacts to upstream/downstream landowners Upcoming Tasks Develop additional benefit information Develop costs for any negative impacts Narrow down capacity alternatives Choose 1 alignment 28 January

23 Local Decisions What level of risk is tolerable? 36 feet for a 500-year event. What locally preferred options need to be retained? MN 35K, ND 30 & 35K Identify sponsors for construction and ongoing O&M Define non-federal cost sharing arrangements Non-federal share of the NED plan will be 35-50% of costs All costs in excess of the NED plan are 100% non-federal Develop local consensus 28 January

24 F-M METRO STUDY TIMELINE Feb 2010: Feb 2010: Mar 2010: Apr 2010: May 2010: Sep 2010: Dec 2010: Jan 2011: Apr 2012: Identify unofficial tentatively selected plan Public Meeting Independent External Peer Review Corps headquarters approval to release draft Formal Public Review of Feasibility Report Finalize feasibility report Transmit recommendation to Congress Begin Plans and Specifications Begin Construction 28 January

25 Red River Basin Wide Feasibility 28 January

26 Red River Basin Wide Feasibility Project Overview Sponsors MN Red River Watershed Management Board ND Red River Joint Water Resource District Cost Share 50/50 All local share as WIK Acceptable WIK Coordinated in advance Provides information beneficial to the Basin 28 January

27 Red River Basin Wide Feasibility Project Overview Phase I LiDAR Collection complete Processing ongoing Development of web viewer Used in 2009 flood Phase II - Modeling HEC-RAS for entire Red River HEC-HMS for watersheds Mike-11 Phase III - Decision Support System Development of tools for local use Modification of RRBDIN (IWI) Needs Local Direction Final Report Basin Goals and Objectives (RRBC) Existing and future conditions Information on tools developed in study 28 January

28 Red River Basin Wide Feasibility Future/Ongoing Work H&H Modeling Mike 11 - RRBC HEC-RAS Corps Extending Cross sections Working with NWS on forecasting HEC-HMS - Corps Decision Support System GIS analysis of LiDAR Identify storage opportunities Identify restoration opportunities Public Outreach and Collaboration (RRBC/IWI) Flood Forecast Tool Drought Forecast Tool Long Term Maintenance, Support, and Upgrades 28 January

29 Red River Basin Wide Feasibility Purpose of Corps Involvement Develop Tools and Information Addressing the Needs of the individual Stakeholders Cities Counties States Watershed Districts No Federal Implementation Sponsors Role Continue to identify needs in the basin Provide financial and political support Continue participation in the study Encourage Public participation in the future. Direct future planning efforts 28 January

30 Questions? Information on back of handout Please sign our sheet to get future mailings. Website: Craig Evans Aaron Snyder Mail: USACE, St. Paul District th St. E. Suite 401 St. Paul, MN January