strategies to mitigate scour critical...
TRANSCRIPT
![Page 1: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/1.jpg)
U.S. Department of Transportation
Federal Highway Administration
Strategies to Mitigate Scour Critical Structures
Dan Ghere
Hydraulics Engineer
(708) 283-3557
![Page 2: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/2.jpg)
Support Material
HEC 23, Bridge Scour and Stream Instability
Countermeasures, Volumes 1 & 2
NCHRP 135048, Countermeasure Design for Bridge
Scour and Stream Instability
NCHRP Report 568, Riprap Design Criteria,
Recommended Specifications, and Quality Control
NCHRP Report 593, Countermeasures to Protect Bridge
Piers from Scour
HEC 18, Evaluating Scour at Bridges
![Page 3: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/3.jpg)
Design Frequency
Risk Based Design
HEC 18 Tables 2.1 & 2.3 combined
![Page 4: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/4.jpg)
Bridge Design Life – 75 Years
Hydraulic Design Flood Frequency – Q50
Probability of Exceedance –
Scour Design Flood Frequency – Q100
Probability of Exceedance –
Scour Check Flood Frequency – Q200
Probability of Exceedance - 31.3%
Probability of Exceedance Example
78%
59.2%
![Page 5: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/5.jpg)
Flood Exceedance ProbabilityHEC 18, Appendix B
![Page 6: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/6.jpg)
Hydraulic Countermeasure Types
• Riprap
• Partially Grouted Riprap
• Articulated Concrete Blocks
• Gabions & Gabion Mattresses
• Concrete Armor Units (Toskanes, A-Jacks, etc.)
• Spurs
• Bendway Weirs
• Guide Banks
• Longitudinal Peaked Stone Toe Protection
![Page 7: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/7.jpg)
Riprap Countermeasures
• Riprap Revetment – channel bank
• Riprap Embankment Overtopping
• Riprap at Bridge Piers
• Riprap at Abutments
• Riprap for Bottomless Culverts
![Page 8: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/8.jpg)
Similarities
• Stone quality specification
• Gradation specifications
• Filter requirements
![Page 9: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/9.jpg)
Differences
• Equations for sizing
• Layer thickness
• Toe detail
• Lateral extent
• Filter extent
![Page 10: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/10.jpg)
HEC 23 Riprap Equations
Revetment (DG 4)
D30 = 𝐲 (𝐒𝐟𝐂𝐬𝐂𝐯𝐂𝐓)[𝐕
𝐊 𝐒𝐠 −𝟏 𝐠𝐲 𝟏/𝟐 ]2.5
Bridge Piers (DG 11)
D50 = 𝟎.𝟔𝟗𝟐 𝑽𝟐
𝑺𝒈 −𝟏 𝟐𝒈
Abutments (DG 14)
𝑫𝟓𝟎 =
𝒌𝒚
(𝑺𝒈 −𝟏)x
𝑽𝟐
𝒈𝒚for FR ≤ 0.8
𝑫𝟓𝟎 = 𝒌𝒚
(𝑺𝒈 −𝟏)x [
𝑽𝟐
𝒈𝒚] 0.14 for FR > 0.8
![Page 11: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/11.jpg)
Riprap Calculator
• Revetment
• Pier
• Abutment/Guide Bank
• Spur
• Embankment Overtopping
• Culvert Outlet
• Open Bottom Culvert
• Wave Attack
![Page 12: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/12.jpg)
![Page 13: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/13.jpg)
![Page 14: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/14.jpg)
Layer Thickness
• Abutments: Not less than 1.5 D50 or D100
• Channel Lining: Not less than 1.5 D50 or D100
• Piers: 3D50 or depth of contraction scour. When
placed under water increase thickness by 50 %.
![Page 15: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/15.jpg)
Lateral Extent
HEC 23 recommends
twice pier width.
I recommend a minimum
of 10 ft. to account for effects
of debris or changes in
skew over time.
Note: filter extends only 2/3
riprap extent at piers.
![Page 16: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/16.jpg)
Lateral Extent at Abutment (minimum)
• Upstream - cover abutment
spill thru cone.
• Downstream – 2 times flow
depth or 25 ft. past cone.
• Toe (apron) – 2 times flow
depth or 25 ft.
![Page 17: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/17.jpg)
Abutment Toe Details
![Page 18: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/18.jpg)
Keys to Successful Riprap Installations
• Stone Quality
Need strong quality spec and material inspection
procedures.
• Excavation for placement
Excavate to plan depth and finish surface for uniform
placement depth.
• No mounding at piers or for toe protection.
• Install and anchor filters underwater
Filter controls the movement of soil particles. Riprap
holds filter in place.
![Page 19: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/19.jpg)
Filter Systems
• Granular
• Geotextile
• Combined – Geotextile with granular cover
Granular cover provides a layer of protection
from puncturing by riprap placement.
![Page 20: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/20.jpg)
Installations Underwater
DOTs report that few riprap installations in water
have filters placed during construction.
Why?
Contractors say it’s too difficult and they don’t know
how.
![Page 21: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/21.jpg)
![Page 22: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/22.jpg)
![Page 23: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/23.jpg)
![Page 24: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/24.jpg)
![Page 25: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/25.jpg)
![Page 26: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/26.jpg)
![Page 27: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/27.jpg)
![Page 28: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/28.jpg)
![Page 29: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/29.jpg)
Environmental Concerns
• Increased water surface caused by obstructions
• Maintaining natural river bed
• Obstruction to fish passage
• Length of loss of native stream bed and banks
![Page 30: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/30.jpg)
What's wrong with this installation?
![Page 31: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/31.jpg)
Construction Supervision
Verify
• Excavation and surface preparation
• Placement of filter
• Stone size gradation & quality (check before
installation)
• Thickness of layer
• Lateral Extent
• Elevation of finished surface (Not to create
mounding on streambed)
![Page 32: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/32.jpg)
Maintenance Inspection
Changed appearance
• Lose of stones
• Reduced stone size (freeze thaw or abrasion)
• Filter is visible through voids
• Lateral extent
• Sloughing or sliding down bank
Document findings (text description and photos)
![Page 33: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/33.jpg)
![Page 34: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/34.jpg)
Poor Quality Stone
![Page 35: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/35.jpg)
![Page 36: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/36.jpg)
![Page 37: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/37.jpg)
Essentials for a Durable lasting Riprap Countermeasure
• “A” Quality Stone
• Proper size and gradation of stone
• Filter under countermeasure
• Layer thickness
• Maintenance inspection and repair
![Page 38: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/38.jpg)
Alternatives to Riprap
Articulated Concrete Blocks (Allows some flexibility)
• Interlocking geometries
• Cable tied blocks
• Interlocking or cabled and vegetated
![Page 39: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/39.jpg)
Applications for Articulated Blocks
• Insufficient vertical clearance for equipment for
riprap installation.
• Necessary riprap stone size not available.
• Necessary stone quality not available.
Requires well prepared uniform surface for installation.
![Page 40: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/40.jpg)
Articulating Block Systems
Interlocking Cable Tied
![Page 41: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/41.jpg)
Layout Detail
![Page 42: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/42.jpg)
Alternatives to Riprap
• Gabions and Gabion Mattresses
![Page 43: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/43.jpg)
Applications for Gabions and Mattresses
• Required riprap size not available.
• High velocity and limited space for placing large
size stone.
• Can serve as retaining wall as well as scour
countermeasure.
![Page 44: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/44.jpg)
Partially Grouted Riprap
![Page 45: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/45.jpg)
Avoid Fully Grouted Riprap
![Page 46: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/46.jpg)
Alternatives to Riprap
• Concrete Armor Units (Toskanes, A-Jacks, etc.)
![Page 47: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/47.jpg)
Toskanes placed like Riprap
![Page 48: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/48.jpg)
A-Jacks Installed as a Unit
![Page 49: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/49.jpg)
![Page 50: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/50.jpg)
Concrete Armor Units: A-Jacks
![Page 51: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/51.jpg)
Hard Points – Similar to Bend Way Weirs
![Page 52: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/52.jpg)
Current Countermeasure Research
• NCHRP 24-42, Techniques for Installation of Filters
Underwater. (2-yr. project just getting started)
• FHWA - USGS Interagency Project. Performance
Evaluation of Existing Countermeasures. (Feb. 2016)
Objective: Inspect and evaluate the
effectiveness of existing policies, design
procedures, and installation of scour
countermeasures.
![Page 53: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/53.jpg)
Interest in Countermeasure Webinar
Provide comments on evaluation sheet if interested
in webinar.
Identify specific coverage areas of interest.
![Page 54: Strategies to Mitigate Scour Critical Structuresctt.mtu.edu/sites/ctt/files/resources/2014bridgeconference/5_ghere.pdf · Strategies to Mitigate Scour Critical Structures Dan Ghere](https://reader031.vdocument.in/reader031/viewer/2022022018/5b915d1109d3f215288b75df/html5/thumbnails/54.jpg)
Questions
FHWA Hydraulics Website:
www.fhwa.dot.gov/engineering/hydraulics
Dan Ghere
FHWA Hydraulics Engineer
Matteson, Illinois
(708) 283-3557