Vaughn Collins, PE, CFM, Northwest Hydraulic Consultants Brad Livingston, Oregon Department of Transportation Melissa Reich, North Coast Land Conservancy
Location
Necanicum River 75 sq mi watershed Active Forestry Highways 101 and 26 0 10 5 Miles
Hwy 101 Flooding Cannon Beach Seaside Normal: 10 mi, 15 minutes Flood: 70 miles, 2 Hours Astoria Detour Seaside Cannon Beach Necanicum Watershed 0 5 10 Miles Sources: Esri, GEBCO, NOAA, National Geographic, DeLorme, HERE, Geonames.org, and other contributors
Frequency and Costs Delay Costs 10,500 ADT Support ~$10m illion 4 project Other Impacts Schools Hospital Access 8 7 6 5 3 2 1 0 Total Duration 143 Hours 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Average Incidents/year: 3.3 Average Hours/year: 44
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
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
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
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
Topography Pacific Ocean Perched River Neawanna Creek
Human Impacts Pacific Ocean Berms Road Fill Building Fill
Flood Levels Pacific Ocean Perched River Fill Impacts Avulsion Risk Utilities
Alternatives Pacific Ocean Beach Bypass Dooley Bridge Road Trestles Road Raises Berm Removal Avulsion Spillway
Alternatives Analysis Alternatives Ranked Preferred Alternative West Bank Berm Removal New Highway Berms Phased Approach Hydrologic Uncertainty Beerman Creek Bridge
Circle Creek Ranch NCLC Owned Long- Term Restoration Goals Supported Berm Removal Restoration $$ not in hand Pacific Ocean
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
Project Design & Construction Design 2012 Constructed 2013 Planting Ongoing
Project Design River Berm Removal
Project Design Floodplain Restoration Engineered Log Jams
Project Design Railroad Berm Removal Swamp Berm Removal
Results February 2014
Results September 2013 Flood River 1.8 Ft Lower No Road Flooding 21 Hrs Flooding Avoided February 2014 Road barely flooded 101 @ Junction flooded More effective than predicted 22 21 20 19 18 Post Project Pre Project 25 26 27 28 29
The Future Continued Restoration Activities Continued Gaging Additional Actions?? New Berms, Bridges Avulsion Risk Mitigation
Conclusion Gaging Network Single Landowner Simple & Low Cost Solution Mitigation Bank Funding Immediate Validation