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Bridge Scour Prevention
Presentors:
Tom Hardinger – Wisconsin DOT
Eugene Hietpas – Collins Engineers Inc.
This presentation and its contents may not be duplicated or reproduced without the expressed written consent of Collins Engineers, Inc.
NC Region Various Structures – Structures B-37-0187, B-71-0018, B-49-0090
Background Information
Design Phase Construction Phase As-Builts
Background Information
Project included 3 bridges over Wisconsin River (Marathon, Portage and Wood Counties in central Wisconsin).
Substructure units are conventional seal, footing and pier walls.
Major flood events 2008, 2010 and 2011.
Post-flood dive inspections revealed major scour issues with streambed and/or substructure undermining.
Project initiated in 2011 and built in late 2012.
B-37-187, STH 34, KnowltonBuilt 1969.Multi-span steel
girder spans.20-38’ water depth.8-10’ streambed
degradation during 2008 flood exposed seal-to-rock interface. Mitigated piers 2 and 3.
B-49-90, CTH HH, Stevens PointBuilt 1999.Multi-span pre-
stressed girder spans.
8-15’ water depth.Pier 4 Seal
undermining at upstream nose.
B-49-90 Existing Condition
B-71-18, STH 73, NekoosaBuilt 1962.Multi-span steel
girder spans.15-22’ water
depth.Localized scour at
piers 2 thru 6.
Design Considerations
• Permanent vs. Temporary Repairs.
• Alternatives.
• Conventional Riprap placement.
• Articulated grout mats/grout bags and structural grout.
• Traffic disruptions.
• Environmental.
• Project Inspection - Most work underwater.
Design Challenges
• Limited WDOT history/experience (design and construction).
• HEC 23 guidelines.
• Input from other states: Montana, Iowa, MN.
• Input from industry.
• Environmental.
• Aquatic bed impacts.
• Development of Specifications.
Project Detail of Scour Repairs
Project 1009-45-65
• Designed by NCR and BOS.
• Let August 14, 2012.
• Cost $532,111.
• Scour Repair Grout: $4,829/CY (6 CY).
• Grout Bags: $482/CY (402 CY).
• 4 “ Grout Mats: $837/CY (256 CY).
• Contractor: JF Brennan Company, La Crosse.
NC Region Various Structures – Structures B-37-0187, B-71-0018, B-49-0090• Construction
• 3D Imaging• Design Phase/Pre-construction• As-Builts
The Challenge
• Can You See Me Now?
Installation/Layout• Issues
As-Builts
As-Builts
As-Builts
