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09-23-2014 City Council Study Session Packet City of Grand Island Tuesday, September 23, 2014 Study Session Packet City Council: Linna Dee Donaldson John Gericke Peg Gilbert Chuck Haase Julie Hehnke Kent Mann Vaughn Minton Mitchell Nickerson Mike Paulick Mark Stelk Mayor: Jay Vavricek City Administrator: Mary Lou Brown City Clerk: RaNae Edwards 7:00 PM Council Chambers - City Hall 100 East 1st Street Grand Island Study Session - 9/23/2014 Page 1 / 49 City of Grand Island Tuesday, September 23, 2014 Call to Order This is an open meeting of the Grand Island City Council. The City of Grand Island abides by the Open Meetings Act in conducting business. A copy of the Open Meetings Act is displayed in the back of this room as required by state law. The City Council may vote to go into Closed Session on any agenda item as allowed by state law. Invocation Pledge of Allegiance Roll Call A - SUBMITTAL OF REQUESTS FOR FUTURE ITEMS Individuals who have appropriate items for City Council consideration should complete the Request for Future Agenda Items form located at the Information Booth. If the issue can be handled administratively without Council action, notification will be provided. If the item is scheduled for a meeting or study session, notification of the date will be given. B - RESERVE TIME TO SPEAK ON AGENDA ITEMS This is an opportunity for individuals wishing to provide input on any of tonight's agenda items to reserve time to speak. Please come forward, state your name and address, and the Agenda topic on which you will be speaking. Grand Island Study Session - 9/23/2014 Page 2 / 49 City of Grand Island Tuesday, September 23, 2014 Study Session Item -1 Update on Northwest Grand Island Flood Control Project Staff Contact: John Collins, P.E. - Public Works Director Grand Island Study Session - 9/23/2014 Page 3 / 49 Council Agenda Memo From:Terry Brown PE, Assistant Public Works Director Meeting:September 23, 2014 Subject:Update on Northwest Grand Island Flood Control Project Item #’s:1 Presenter(s):John Collins PE, Public Works Director Background Sections of Northwest Grand Island experienced significant flooding during the 1967 flood. Most of the area north of Capital Avenue and west of Broadwell Avenue is within the 100 year flood plain, as well as the area between Webb Road and US Highway 281 bounded by Capital Avenue on the north and State Street on the south. There have been flood control improvements built in the area in the past, but the Moores Creek Watershed and northern Grand Island can still suffer considerable flood damage due to spill over of flood waters from two (2) other watersheds, namely Silver Creek and Prairie Creek. The City of Grand Island has been working with the Central Platte Natural Resources District (CPNRD) for the past several years on a flood control project for the Upper Prairie/Silver/Moores Creek. This project will protect a significant portion of Northwest Grand Island from flooding. On January 11, 2005 the Grand Island City Council approved Resolution No. 2005-15, which gave approval for the City to enter into an Interlocal Agreement with the Central Platte Natural Resources District (CPNRD), Hall County, and Merrick County. Such resolution authorized City funding of 46.25% of the $7.8 million, or $360,750 each year for ten (10) years, for a total amount of $3,607,500.00. Total project cost was estimated to be $16,400,000.00 at this time. Discussion With this project approaching the ten (10) year mark it is necessary to provide an update on the status of this project. Grand Island Study Session - 9/23/2014 Page 4 / 49 Conclusion This item is presented to the City Council in a Study Session to allow for any questions to be answered and to create a greater understanding of the issue at hand. It is the intent of City Administration to bring this issue to a future council meeting for the approval of a resolution for further funding of this project. Grand Island Study Session - 9/23/2014 Page 5 / 49 1 UPPER PRAIRIE/SILVER/MOORE’S CREEK FLOOD CONTROL PROJECT (NORTHWEST FLOOD CONTROL PROJECT) Council Study Session | Grand Island, NE | September 2014 Presented by John G. Petersen, PE Grand Island Study Session - 9/23/2014 Page 6 / 49 2 Upper Prairie/Silver/Moore’s •Presenters –Lalit K. Jha, PE, D.WRE., CFM •Senior Project Manager •Involved in this project since 2005 –John G. Petersen, PE •Project Manager •Lead Designer Grand Island Study Session - 9/23/2014 Page 7 / 49 3 Project Overview Project Goals Provide 100-yr flood protection to NW Grand Island Reduce flood damages to crops, properties, and other infrastructure Removal of properties from FEMA Floodplain Project Benefits (Based on 2004 Feasibility Study) Eliminate $59 million in damages from 100-yr event Protect 1500 residences and 55 businesses from flood damage Protect over 10,000 acres of cropland Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 8 / 49 4 Project Sponsors Natural Resources Development Fund (NRDF) Central Platte NRD City of Grand Island Hall County Merrick County Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 9 / 49 5 Project Background Feasibility Study Completed in 2004 Estimated Total Project Cost of $16 Million Design Began in 2005 Anticipated Project Completion 2018-2019 One of the Largest NRDF Projects Estimated Total Project Cost of $29 Million Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 10 / 49 6 Background Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 11 / 49 7 Background Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 12 / 49 8 Background Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 13 / 49 9 Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 14 / 49 10 Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 15 / 49 11 Hydrology and Hydraulics Dry, Prairie, Silver, and Moores Creeks Approximately 230 Square Mile Drainage Area Uplands and Lowlands Timing of Hydrographs Flows Crossing Basin Divides Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 16 / 49 12 Project Components Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 17 / 49 13 Upper Prairie/Silver/Moore’s Changes in Peak Flows 2600 cfs 1130 cfs 2580 cfs 1800 cfs 800 cfs 80 cfs 1600 cfs 800 cfs 800 cfs 800 cfs 1130 cfs 1300 cfs0 cfs cfs = cubic feet per second 1 cfs = 450 gallons per minute Grand Island Study Session - 9/23/2014 Page 18 / 49 14 Naming Convention: UL = Upland (In the Hills) LL = Lowland (In the Valley) PC = Prairie Creek SC = Silver Creek DC = Dry Creek Example: PCUL 4 = Prairie Creek UpLand Structure #4 Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 19 / 49 15 Detention Cells 3.8 Million CY Excavation to Date 2.0 Million CY Excavation Remain Reduce Silver Creek flows from about 1130 cfs to 80 cfs (100-yr) Upper Prairie/Silver/Moore’s Auxiliary Spillway Principal Spillway Grand Island Study Session - 9/23/2014 Page 20 / 49 16 Detention Cells Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 21 / 49 17 Dry Dams PCUL 4 & DCUL 6 Construction Complete in 2013 PCUL 1 & PCUL 2 Construction In Progress, Estimated Completion by December 2014 Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 22 / 49 18 Dry Dams PCUL 4 57,000 CY Excavation Inflow = 3150 cfs Outflow = 60 cfs Drainage Area = 4.5 mi2 100-yr Flood Pool = 120 Acres Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 23 / 49 19 Dry Dams DCUL 6 74,000 CY Excavation Inflow = 3650 cfs Outflow = 130 cfs Drainage Area = 3.5 mi2 100-yr Flood Pool = 85 Acres Road Dam Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 24 / 49 20 Dry Dams PCUL 4 After 4 inches of rain Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 25 / 49 21 Dry Dams PCUL 1 203,000 CY Excavation Inflow = 3950 cfs Outflow = 125 cfs Drainage Area = 13.0 mi2 100-yr Flood Pool = 265 Acres High Hazard Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 26 / 49 22 Dry Dams PCUL 2 282,000 CY Excavation 2 Dams, 1 Outlet Inflow = 4300 cfs Outflow = 120 cfs Drainage Area = 9.3 mi2 100-yr Flood Pool = 232 Acres High Hazard Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 27 / 49 23 Silver/Moore’s Levee <2 Miles FEMA Design Standards Last Line of Defense Design Starting Construction TBD Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 28 / 49 24 Conditional Letter of Map Revision (CLOMR) Existing and Proposed Conditions Existing Conditions are Changing! Including Moore’s Creek Flood Study Coordination with FEMA Region VII, DNR, Etc. Speed up the Map Revision Process Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 29 / 49 25 Conditional Letter of Map Revision (CLOMR) Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 30 / 49 26 Other Project Pieces Minor Ditch Connections Operation and Maintenance Manual LOMR Moore’s Creek Flood Study and Master Plan Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 31 / 49 27 Overall Project Schedule –Design of Upland Dams Complete –Design of Benton & Still Rehab On Hold –Design of Levee Summer 2013 to Winter 2014 –Construction of DCUL6 & PCUL4 Complete –Construction of PCUL1 & PCUL2 June 2014 to December 2014 –Construction of Benton & Still Rehab TBD –Construction of Levee TBD (2015) –Construction of Final Detention Cells TBD (2016-2017) –Approval of Letter of Map Revision (LOMR) TBD (2018-2019) Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 32 / 49 28 Project Costs •Estimated Project Cost (2014): ~$28,200,000 NRDF (52.5%) Cost Share: ~$15,540,000 Local Cost Share (47.5%): ~$14,060,000 Project Cost Breakdown: 1. Feasibility Study - $264,500 2. Land Acquisition - $4,600,000 3. Engineering – $2,800,000 4. Construction - $20,100,000 O, M, & R Costs - $460,000 Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 33 / 49 29 Project Costs •Estimated Project Cost (2014): ~$28,200,000 NRDF (@52.5%) Cost Share: ~$14,802,305 Local Cost Share (47.5%): –CPNRD (@21.97%) ~$6,194,412 –City of Grand Island (@21.97%) ~$6,194,412 –Hall County (@2.38%) ~$671,038 –Merrick County (@1.19%) ~$335,519 Upper Prairie/Silver/Moore’s Grand Island Study Session - 9/23/2014 Page 34 / 49 30 MOORE’S CREEK FLOOD STUDY AND MASTER PLAN Council Study Session | Grand Island, NE | September 2014 Grand Island Study Session - 9/23/2014 Page 35 / 49 31 Moore’s Creek Moore’s Creek Background 15,000 Acres 30% Urban 70% Rural / Agriculture On-going Development on the West side of the City Court Order to Restrict Flows Downstream Grand Island Study Session - 9/23/2014 Page 36 / 49 32 Moore’s Creek Background Original Floodplain/Flood Risks Identified based upon Hydrology Study in 1980’s Significant Changes since Original Study Moore’s Creek Hydrology = Study of Rainfall vs Runoff Grand Island Study Session - 9/23/2014 Page 37 / 49 33 Moore’s Creek Moore’s Creek Background 2004 Feasibility Study No Detailed Hydrology or Hydraulics for Moore’s Creek Assumed primary Flood Risk due to Overflows from Silver/Prairie Creeks Hydraulics = Study of Conveyance vs Flood Elevations Grand Island Study Session - 9/23/2014 Page 38 / 49 34 2008 Floodplain Maps Updated In Floodplain, near City 900 Parcels; $150M 730 Structures 600 Residential 130 Non-Residential Moore’s Creek Grand Island Study Session - 9/23/2014 Page 39 / 49 35 Floodplain and Flood Insurance Implications Floodplain Management Restrictions to the Types of Structures that can be built in the Floodplain, and where Biggert Waters Act of 2012 Changes in how Flood Insurance Rates are Determined Increases Financial Stability of the NFIP, less Tax burden Can Have Significant Financial Impacts to Cities in the Floodplain Grimm Waters Act of 2014 Enacted to dampen the Financial Impacts Phased Implementation of New Insurance Rates over Several Years Moore’s Creek Grand Island Study Session - 9/23/2014 Page 40 / 49 36 BW-12 and Rebuilding Decisions Elevation lowers premiums “ZONE A” EXAMPLE Elevating 3 feet above the BFE could lower premiums significantly! Homes built below BFE could be hit hard by an increase to full-risk rates Slide and Graphic Provided by FEMA Moore’s Creek Grand Island Study Session - 9/23/2014 Page 41 / 49 37 Moore’s Creek Flood Study Detailed H&H Analyses Considers Flood Control Projects Currently Underway in Dry/Prairie/Silver Reduction/Elimination of Overflows From other Creeks Impacts from New Development Accurate assessment of current Flood Risks Moore’s Creek Hydrology Model H&H = Hydrology and Hydraulics Grand Island Study Session - 9/23/2014 Page 42 / 49 38 Moore’s Creek Flood Study In conjunction with Floodplain Remapping efforts (CLOMR) for Prairie and Silver Creeks 2018-2019 Anticipated Completion of Floodplain Remapping GOAL – Remove Properties from the Floodplain Moore’s Creek Grand Island Study Session - 9/23/2014 Page 43 / 49 39 Moore’s Creek Master Plan Analyses of Future Development based upon Future Landuse Review Stormwater Regulations and Policies Anticipated Completion 2015 Moore’s Creek Ensure Future Development is done in a responsible manner, consistent with Court mandates Grand Island Study Session - 9/23/2014 Page 44 / 49 40 Moore’s Creek Master Plan Capital Improvement Program Project Development Flood Control and other Drainage Improvements Proposed Conditions Floodplain Delineations Moore’s Creek Grand Island Study Session - 9/23/2014 Page 45 / 49 41 Moore’s Creek Flood Study, Master Plan and Northwest Flood Control Projects Overall Comprehensive Effort to Reduce Flood Risks and Drainage Issues, and Educate to Residents of the City of Grand Island and Hall County Moore’s Creek Grand Island Study Session - 9/23/2014 Page 46 / 49 42 Thank you! Grand Island Study Session - 9/23/2014 Page 47 / 49 MOORE’S CREEK FLOOD STUDY AND MASTER PLAN In conjunction with the NORTHWEST FLOOD CONTROL PROJECT CITY OF GRAND ISLAND, HALL COUNTY AND CENTRAL PLATTE NRD JEO CONSULTING GROUP, INC:, Upper P-S-M Project Overview PROJECT OVERVIEW for NEWSLETTER/PRESS RELEASE The City of Grand Island (City) has partnered with Hall County (County) and the Central Platte Natural Resources District (CPNRD) to investigate the flooding that occurs in the northwest portion of the City. The project involves a detailed analysis of the hydrology and hydraulics of the upper parts of the Prairie, Silver, Dry, and Moore’s Creek watersheds primarily in rural Hall County. A Feasibility Report was completed in 2004, detailing findings of the H&H analysis and proposed several flood mitigation projects with the ultimate goal of reducing flood damages and removing several hundred homes and businesses from the FEMA Floodplain. The overall proposed project will provide flood protection for the 100-yr storm to urban, residential, and commercial properties in western and northern Grand Island, generally south of Highway 2 and west of Highway 281. Secondary purposes of the project are to: provide 100-yr flood protection to crop land and rural residents; reduction of road and bridge damages; reduction of the rural 100-yr floodplain extents; and removal of northern and western Grand Island from the FEMA Floodplain. To accomplish these goals, several flood control structures are undergoing design and/or construction including: lowland detention cells; floodwater retarding dams; and a section of levee. In 2013, JEO began efforts to reassess the FEMA floodplain through the Conditional Letter of Map Revision (CLOMR) process. Removal of structures will have significant economic impacts due to recent changes in the National Flood Insurance Program (NFIP). Many federal assistance subsidies will be removed thereby returning insurance rates to more risk-based levels and providing more financial stability to the program. The remapping done as part of this project is intended to significantly reduce flood risks, reduce the size of the floodplain, and thus reduce flood insurance requirements. Proposed flood control structures, upon construction, will significantly impact floodplain extents. Therefore, these structures will be incorporated into a revised floodplain analysis and submitted to FEMA for adoption. The Moore’s Creek watershed is partially located within the City, and is therefore of particular interest with respect to the floodplain. Though the floodplain maps for the City were updated in 2008, they do not accurately reflect the Moore’s Creek floodplain due to recent flood control projects and new development. For this reason, the City is conducting a Flood Study to reassess the floodplain. A public open house will be conducted later this year to inform residents of the findings of the Flood Study. Further phases of the project will include a Master Plan for Moore’s Creek, to identify additional measures to reduce flood risks and encourage responsible new development. If you have any questions regarding this project, feel free to contact: · Terry Brown, Assistant Public Works Director, terryb@grand-island.com, 308-385-5444 · Chad Nabity, Regional Planning Director, chadn@grand-island.com, 308-385-5240 Grand Island Study Session - 9/23/2014 Page 48 / 49 Prairie Cr. W ood R iverSil v er C r.Platte RiverBoxelder Cr.Moores Cr.N Channel Platte RiverS o u th L o u p R iv e rTrib of Prairie Cr.Beaver Cr. T r i b o f B o x e l d e r C r .Warm SloughEsri, HERE, DeLorme, MapmyIndia, © OpenStreetMap contributors Upper Prairie/Silver/Moore's Creek Flood Control Projectalso known as the Northwest Flood Control ProjectCentral Platte NRD and City of Grand Island Created By: SMSDate: 06/18/2014Software: ArcGIS 10.2File: 310D2 This map was prepared using information from record drawingssupplied by JEO and/or other applicable city, county, federal, or public orprivate entities. JEO does not guarantee the accuracy of this mapor the information used to prepare this map. This is not a scaled plat. Grand Island Flood Control ProjectsGrand Island Flood Control Projects Dam DCUL 6 Dam PCUL 4 Dam PCUL 2 Dam PCUL 1 Silver/Moores Levee 00 10,00010,000 20,00020,0005,0005,000 FeetFeet ´´ Detention CellsGrand IslandStudy Session - 9/23/2014Page 49 / 49