water resource specialists

Transcription

1 Vaughn Collins, PE, CFM, Northwest Hydraulic Consultants Brad Livingston, Oregon Department of Transportation Melissa Reich, North Coast Land Conservancy

2 Location

3 Necanicum River 75 sq mi watershed Active Forestry Highways 101 and Miles

4 Hwy 101 Flooding Cannon Beach Seaside Normal: 10 mi, 15 minutes Flood: 70 miles, 2 Hours Astoria Detour Seaside Cannon Beach Necanicum Watershed Miles Sources: Esri, GEBCO, NOAA, National Geographic, DeLorme, HERE, Geonames.org, and other contributors

5 Frequency and Costs Delay Costs 10,500 ADT Support ~$10m illion 4 project Other Impacts Schools Hospital Access Total Duration 143 Hours Average Incidents/year: 3.3 Average Hours/year: 44

6 Stakeholders Oregon Department of Transportation Clatsop County Cities of Seaside, Cannon Beach, Warrenton, Gearhart & Astoria Port of Astoria North Coast Land Conservancy Local Businesses Community

7 Goals and Objectives Goal: Hwy 101 will provide uninterrupted function during most years Significantly reduce frequency of 101 roadway restrictions and closures Do not increase flood risk on nearby structures and infrastructure Improve Necanicum River basin ecological conditions Engage and inform the community and visitors Focus on cost-effective, technically feasible and quickly implementable projects

8 Existing Conditions: Changes in Flood Behavior? Channel sedimentation No Log Jams Not at 101 problem locations Road Settlement Possible Timber Harvest Possible Climate Change/Variability Possible Floodplain Construction - Yes

9 Lower Necanicum Floodplain Pacific Ocean Sources: Esri, HERE, DeLorme, USGS, Intermap, increment P Corp., NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, MapmyIndia, OpenStreetMap contributors, and the GIS User Community

10 Topography Pacific Ocean Perched River Neawanna Creek

11 Human Impacts Pacific Ocean Berms Road Fill Building Fill

12 Flood Levels Pacific Ocean Perched River Fill Impacts Avulsion Risk Utilities

13 Alternatives Pacific Ocean Beach Bypass Dooley Bridge Road Trestles Road Raises Berm Removal Avulsion Spillway

14 Alternatives Analysis Alternatives Ranked Preferred Alternative West Bank Berm Removal New Highway Berms Phased Approach Hydrologic Uncertainty Beerman Creek Bridge

15 Circle Creek Ranch NCLC Owned Long- Term Restoration Goals Supported Berm Removal Restoration $$ not in hand Pacific Ocean

16 Funding How to Fund? Off of ODOT Right of Way FEMA Mitigation Grant Habitat Restoration Grant ODOT Wetland Mitigation Bank Existing ODOT Program Necanicum Watershed Mitigation Credits Added Restoration Component NCLC retains ownership Immediate Implementation

17 Project Design & Construction Design 2012 Constructed 2013 Planting Ongoing

18 Project Design River Berm Removal

19 Project Design Floodplain Restoration Engineered Log Jams

20 Project Design Railroad Berm Removal Swamp Berm Removal

21 Results February 2014

22 Results September 2013 Flood River 1.8 Ft Lower No Road Flooding 21 Hrs Flooding Avoided February 2014 Road barely flooded Junction flooded More effective than predicted Post Project Pre Project

23 The Future Continued Restoration Activities Continued Gaging Additional Actions?? New Berms, Bridges Avulsion Risk Mitigation

24 Conclusion Gaging Network Single Landowner Simple & Low Cost Solution Mitigation Bank Funding Immediate Validation