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Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
Site Remediation And Mitigation Plan
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Site Remediation And Mitigation Plan

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Part II of our senior design project. My design.

Part II of our senior design project. My design.

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  • 1.
    • Rockfall Hazard Rating for Road Cuts between Rolla and Vienna II. Site Remediation and Mitigation Plan for Site E Four Miles North of Rolla, MO on Highway 63
    • Daniel Stout
    • Evan Stevens
    • Brian Mullen
  • 2. Part 1: Rate all Rock Cuts on Highway 63 between Rolla and Vienna, MO
    • How?
      • Missouri Rock Fall Hazard Rating System
        • Maerz et. al., 2005
        • “ Missouri System”
      • Oregon Rock Hazard Rating System
        • Pierson & Van Vickle, 1993
        • “ Oregon System”
    • Both use similar factors to rate rock fall hazards
    • Oregon system tailored for mountainous terrain
    • Missouri system designed for more moderate terrain; includes karst variables
  • 3. In the beginning…
    • 36 individual sites
    • L & R sides rated separately
    • Digital video analysis and site visits used to gather data
  • 4. “ Missouri System”
    • RISK
      • Slope height
      • Slope angle
      • Rock face instability
      • Weathering & Erosion
      • Rock strength
      • Face irregularity
      • Face looseness
      • Block size
      • Water
      • Karst
    • CONSEQUENCE
      • Ditch width
      • Ditch volume
      • Rockfall quantity
      • Slope angle
      • Shoulder width
      • Number of lanes
      • Daily traffic
      • Average vehicle risk
        • (Cars/day * length)/(Speed limit * cut length)
      • Decision Sight Distance
      • Block size
  • 5. “Missouri System”
    • Rate factors, then sum risk 1-100
    • Rate factors, then sum consequence 1-100
  • 6. “Oregon System”
    • Factors
      • Slope height
      • Ditch effectiveness
      • AVR
      • DSD
      • Structural condition & erosion
      • Block size/quantity
      • Climate/Water
      • Rock fall history
    • Each factor rated
      • 3 (good)
      • 9 (fair)
      • 27 (poor)
      • 81 (bad)
    • Summation of all values gives score; maximum 810
    • >500 needs “immediate action”
    • 300-500 “of concern”
  • 7. “Missouri system” results Site E Site D Site K
  • 8. “Oregon System” results
    • Sites E, D, and K elevated in this model too
    • E = 222/810
    • Other sites (red arrows) perhaps “inflated” by AVR
  • 9. Part I Results
    • Site E clearly highest rated site by both methods
    • A few other sites may need attention
  • 10. “Site E”
    • Four miles north of Rolla, fifth cut on right
    • Just past Capital Quarry
    www.terraserver.com Earth.google.com
  • 11. The Paleosinkhole
    • Cut is approx. 50 years old
    • Stands at 76 degrees
    • Heterogeneous jumbled up mass
    • Matrix like a calcrete or caliche
    • Dolomite boulders and broken strata
  • 12. A short slideshow
    • Left and right contacts
    • Jumbled mass of dolomite in a calcrete mix
    • Overhanging slab at top
    • Ravel Pile
  • 13.
    • Right contact
    • Dry
    • Slumping/slumped
    • Ditch along top
  • 14.
    • Left contact
    • Wet
    • Highly eroded; water off top and along joints
  • 15.  
  • 16.  
  • 17. Approx. 2’
  • 18. Current Mitigation Practice
  • 19. Possible Remediation or Mitigation
    • Excavation
    • Berms
    • Rocksheds
    • Ditches
    • Rock traps and fences
    • Retaining walls and Gabions
    • Mesh draping
    • Rock netting
    • Shotcrete
    • Rockbolting
    • Soil nailing
    Spang, 1987
  • 20. Chosen Methods to Investigate
    • Gabion Walls
    • Mesh Draping (w/ and w/o rock fencing)
    • Excavation
    Gabion wall on I-44 Mesh draping on a similar slope (Goodman, 1989)
  • 21. Gabion Walls
    • “ Natural looking” stacked baskets of rock
    • Low maintenance
    • Restraining mass
    • Local experience
    • Assumptions
      • Phi = 35 degrees
      • C = 300 psf
      • Values consistent with a strong soil
      • Unit weight = 160 pcf
    • Assignments
      • Wall batter = 6 degrees
      • Porosity of 50 percent
      • 2.7 mm PVC coated wire
      • Top slope of 3 degrees
      • 3 ft top surface height (depth of lowest layer of gabions) aids FOS
  • 22. Design 1: Half-slope Gabion Wall
    • 24 ft gabion wall
    • Benched back 12 ft.
    • Bench covered w/ rip-rap
    • $70-$80,000 depending upon options
    • Overall FOS 1.91
  • 23. Design 2: Full-slope Gabion Wall
    • 48 ft gabion wall
    • Four tiers
    • $180-$220,000
    • Overall FOS 1.69
  • 24. Design 3: Staggered half-slope gabion walls
    • Two 24’ gabion walls staggered with a 12’ (9’) bench
    • Bench covered w/ rip-rap
    • $105-$135,000
    • Overall FOS 1.97
  • 25. Design Cost Comparison
  • 26. Design Comparison 2
  • 27. Maintenance/ Recommendation
    • Design 1
    • Why?
      • Lowest cost
      • Best FOS
      • No FOS < 1.50
      • Others are overkill
    • Not Designs 2 & 3
    • Why?
      • High cost
      • Poor overturning FOS
    • Low maintenance
      • Clear out vegetation, or allow it cover if wanted
      • Check regularly for wire breaks
      • Clean benches (if any) periodically
  • 28. Mesh Draping - General
    • A flexible facing such as wire rope nets or conventional wire meshes are draped over the slope for passive rock fall protection.
    • The draping does not stop rock falls, but rather controls the velocity of falling rocks by limiting the horizontal component.
    • Anchored from above and simply hangs over slope
    (Hoek, 2006)
  • 29. Mesh Draping - Procedure
    • Clean and scale slope
    • Choose net size
    • Anchor support cables
      • Could be problematic given the paleosinkhole material nature
      • Need 20 kips support
    Muhunthan et. al. (2005)
  • 30. Optional Rock Fencing Energy absorbing rock fence that can be used alone or in addition to other methods (Hoek, 2006)
    • Design may or may not include rock fencing as a design element
  • 31. Design 1: 40’ drape w/ rock fence
    • 40’ mesh draping over paleosink
    • 4” x 4” mesh
    • 120’ rock fence across center
  • 32. Design 2: Full-slope draping
    • 55’ draping covers full slope
    • 4” x 4” mesh
  • 33. Draping Comparison
  • 34. Draping Comparison 2
    • Draping with fence provides perhaps the best protection of all designs, but:
      • Removal of accumulated debris is problematic
      • Periodic fence replacement costly (~$21,000)
    • Full-slope draping alleviates above concerns
  • 35. Draping Recommendation
    • Full-slope draping
      • Keeps all but the very smallest and largest rock falls in the ditch
      • Requires little to no maintenance
      • Relatively cheap compared to massive excavation or gabion walls.
    • Problems
      • Paleosink material problematic for placing anchors
      • No protection against rotational failure
  • 36. Excavation
    • Removal of two linear yards into paleosink along entire face
    • 1080 c.y. @ $28/c.y.
    • ~$30,000
    • Note: the $28/c.y. price is a high bid; could be done cheaper
    • What does this do?
      • Temporary
        • Removes weathered face
        • Decreases looseness
        • Decreases face instability
      • Permanent
        • Increases ditch width and volume
        • Slight decrease in slope angle to 70 degrees
  • 37. Excavation effect (49,67) (58,79)
  • 38. Comparison of all Designs
  • 39. Recommended Design
    • Full-slope draping at $53, 414
    • Very good results w/ usage so far, for more info see:
    • Muhunthan et. al. (2005) Analysis and Design of Wire Mesh / Cable Net Slope Protection, Washington State Transportation Center, April 2005.
  • 40. Afterthoughts
    • We’ve noticed numerous paleosinkholes over Missouri in the middle of similar rock cuts that now sit at ~30 degrees and are heavily vegetated. If excavation could be done cheap, cut it back to <30 degrees and vegetate it
    • As we went through this exercise—even at the very end—we continued to discover alternatives
      • There are numerous simple retaining wall structures that might work just fine if all we want to do is control rock, ravel, and roll.
      • Sheet piles, bin walls, etc.
    The next road cut down from Site E has a degraded paleosinkhole…
  • 41. In reality…
    • The slope will probably sit and ravel…
  • 42. Questions?

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