Soil Presentation


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Colorado\'s Swelling Soils, A practical guide for homeowners and buyers.

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  • 5 year old house Garage floor recently replaced – why? Could not get down here 1 st time Strongly recommended opening the structural floor
  • 1 year old floor (replaced after 4 years)
  • I70 road cut E 470 bumps
  • Both a footing pad and voided
  • Picture non-load bearing Stairs on floating slabs should NOT have fixed connections Doors and windows jamb or break, therefore void under door Gas, W and S should be designed so they are completely isolated from areas of concern Furnace = boot
  • “Homeowners in CO should accept the fact that flatwork will crack.” Reinforcement Drill foundations
  • “Intercepts” ground water from higher elevations and flows it around the structure Area = Perimeter drains run out to street drains
  • Slope = whole property Runoff = next to house
  • Zeer-is-scape = coined by Denver Water Xeros = Greek for Dry
  • Maintain slope, Clean gutters, Adjust sprinklers and don’t over water Inspect and caulk flatwork Maintain floor ventilation (Humidistat)
  • Disclosure – New – responsibility of the builder to disclose evidence of soils hazards, including a soils report for each lot, including: -swell potential -observations -recommendations (engineering) Resale – “The presence of swelling soils may be considered an adverse material fact because it can affect the physical condition of, or cause defects in the property.” FD – the buyers own judgment and risk tolerance after being informed.
  • Soil Presentation

    1. 1. Tom Yeager Owner/Certified Inspector NEHA Radon Measurement Cert. # 104169 RT 303-464-9090
    2. 2. Colorado’s Swelling Soils A Practical Guide For Homeowners and Buyers
    3. 3. Reference <ul><li>Colorado Geological Survey </li></ul><ul><li>Special Publication 43, 1997 </li></ul><ul><li>“A Guide to Swelling Soils for Colorado Homebuyers and Homeowners” </li></ul><ul><li>David Noe, Candace Jochim and William Rogers </li></ul>
    4. 4. Overview <ul><li>Geology </li></ul><ul><li>Construction </li></ul><ul><li>Landscaping & Maintenance </li></ul><ul><li>Risk </li></ul><ul><li>Inspection </li></ul>
    5. 5. But Why?
    6. 6. But Why?
    7. 10. Geology <ul><li>“ Swelling Soils” both Soils and Bedrock </li></ul><ul><li>Contain clay minerals that attract and absorb water </li></ul><ul><li>Illite </li></ul><ul><li>Bentonite – a type of Smectite. </li></ul><ul><ul><li>Ancient ash weathered to clay. </li></ul></ul><ul><ul><li>Extremely high swelling characteristics. </li></ul></ul>
    8. 12. Geology - 2 <ul><li>Heaving bedrock </li></ul><ul><ul><li>Upturned bedrock (near mountain uplifts) </li></ul></ul><ul><ul><li>Layers may swell unevenly </li></ul></ul><ul><ul><li>And/or shear-slip movement </li></ul></ul><ul><ul><li>Jefferson and Douglas counties have adopted development regulations to address this special geologic hazard </li></ul></ul>
    9. 13. Controlling Factors <ul><li>Type and concentration of minerals </li></ul><ul><li>Soil density </li></ul><ul><li>Moisture change potential </li></ul><ul><li>Restraining pressure of surrounding soil </li></ul>
    10. 14. Where? <ul><li>Throughout CO (excepting mountain areas) </li></ul><ul><li>Potential for a specific property? </li></ul><ul><ul><li>Like Radon, depends on local geology </li></ul></ul><ul><ul><li>Sampling and laboratory testing are the only way to determine potential </li></ul></ul>
    11. 15. Why? WATER! <ul><li>Increase moisture, increase swelling </li></ul><ul><li>Decrease moisture, increase shrinking </li></ul><ul><li>Natural conditions result in seasonal changes </li></ul><ul><li>Land Development increase moisture in the ground (runoff, irrigation) </li></ul><ul><li>Therefore, one of the most important means of mitigating swelling soil damage is reducing the accumulation of subsurface moisture! </li></ul>
    12. 16. Construction <ul><li>Special Designs and construction methods must be used. </li></ul><ul><li>Depends on the Swell Potential of the soils specific to the site. </li></ul><ul><li>Quality control during construction is the key to the success of the design. </li></ul>
    13. 17. Construction Considerations <ul><li>Ground Preparation and Grading </li></ul><ul><li>Foundations </li></ul><ul><li>Floor Construction </li></ul><ul><li>Interior Construction </li></ul><ul><li>Exterior Flatwork </li></ul><ul><li>Subsurface Drainage </li></ul><ul><li>Surface Drainage </li></ul>
    14. 18. Ground Preparation and Grading Issues: <ul><li>Cutting away high areas </li></ul><ul><ul><li>Exposes swelling soils and/or bedrock (fractures and drying) </li></ul></ul><ul><ul><li>Natural restraining loads removed </li></ul></ul><ul><li>Filling Low areas </li></ul><ul><ul><li>Same expansive soils used for fill </li></ul></ul>
    15. 19. Ground Preparation and Grading Solutions: <ul><li>Overexcavation method of cutting and fill replacement </li></ul><ul><ul><li>3 to 10 feet below lowest level of structure </li></ul></ul><ul><li>Control moisture and density of fills </li></ul><ul><ul><li>Thin layers, water added, compacted </li></ul></ul><ul><ul><li>More moisture = less swell potential </li></ul></ul><ul><li>Chemical treatments </li></ul><ul><ul><li>Changes clay chemistry (roads and commercial) </li></ul></ul>
    16. 20. Foundations <ul><li>Shallow </li></ul><ul><ul><li>Directly supported by foundation excavation materials (bedrock, soil, fill) </li></ul></ul><ul><li>Deep </li></ul><ul><ul><li>Penetrates the soil/bedrock to some depth below the foundation walls transferring the loads to the deeper strata </li></ul></ul>
    17. 21. Foundations - Shallow <ul><li>Spread footing </li></ul><ul><li>Footing pad </li></ul><ul><li>Wall on grade </li></ul><ul><li>Voided wall on grade </li></ul><ul><li>Mat/raft (post-tensioned slab on grade) </li></ul>
    18. 22. Footing pad
    19. 23. Foundations - Deep <ul><li>Drilled pier </li></ul><ul><ul><li>Straight Shafted concrete </li></ul></ul><ul><ul><li>Concrete with grooves </li></ul></ul><ul><ul><li>Helical steel </li></ul></ul>
    20. 24. Drilled pier
    21. 25. Floor Construction <ul><li>Floating Slab </li></ul><ul><li>Structural </li></ul>
    22. 26. Interior Construction <ul><li>Walls (load/non-load bearing) </li></ul><ul><li>Stairs </li></ul><ul><li>Doors and Windows </li></ul><ul><li>Gas, Water and Sewer lines </li></ul><ul><li>Furnace </li></ul>
    23. 29. Exterior Flatwork <ul><li>Driveways </li></ul><ul><li>Sidewalks </li></ul><ul><li>Patios </li></ul><ul><li>Porches </li></ul>
    24. 30. Subsurface Drainage <ul><li>Perimeter Drain </li></ul><ul><li>Sump System </li></ul><ul><li>Interceptor Drain </li></ul><ul><li>Area Drain </li></ul>
    25. 31. Surface Drainage <ul><li>Roof drainage </li></ul><ul><li>Slope Drainage </li></ul><ul><li>Runoff Slope </li></ul>
    26. 32. Overview <ul><li>Geology </li></ul><ul><li>Construction </li></ul><ul><li>Landscaping </li></ul><ul><li>Home Maintenance </li></ul><ul><li>Inspection </li></ul>
    27. 33. Landscaping Issues <ul><li>“Excess Water is the most significant and direct cause of swelling soils damage” </li></ul><ul><li>Irrigation results in unnatural water and moisture levels </li></ul><ul><ul><li>Infiltrates the ground </li></ul></ul><ul><ul><li>Trees and shrubs transpire water </li></ul></ul><ul><ul><li>Impervious covers block evaporation </li></ul></ul>
    28. 34. Landscaping Guidelines Goal is to reduce excess water <ul><li>No flowers or shrubs closer than 5’ to foundation (unless native/low H2O need) </li></ul><ul><li>Plantings near foundation should not disturb the slope </li></ul><ul><li>No Trees closer than 15’ to foundation </li></ul><ul><li>Sprinkler systems should not spray closer than 5’ to foundation </li></ul>
    29. 35. Landscaping Guidelines <ul><li>Use low water vegetation </li></ul><ul><li>Water trees during dry periods to keep them from drawing a lot of water from a large area </li></ul><ul><li>Group plants according to similar water needs </li></ul><ul><li>Irrigation limited to lowest amount </li></ul>
    30. 36. Landscaping <ul><li>Consider “Xeriscape” </li></ul><ul><ul><li>Water wise landscaping </li></ul></ul><ul><ul><li>Can reduce household water use by 50% </li></ul></ul><ul><ul><li>A big component is Mulch Covers </li></ul></ul><ul><ul><ul><li>Organic or inorganic </li></ul></ul></ul><ul><ul><ul><li>Geotextile fabric base </li></ul></ul></ul><ul><ul><ul><li>Create a runoff slope </li></ul></ul></ul>
    31. 37. Home Maintenance <ul><li>Slope, drainage and landscape </li></ul><ul><li>Concrete foundation and flatwork </li></ul><ul><li>Structural floor </li></ul><ul><li>Subsurface Drainage </li></ul><ul><li>Surface Drainage </li></ul>
    32. 38. Inspection - Resale <ul><li>Driveway </li></ul><ul><li>Sidewalks, curbs and gutters </li></ul><ul><li>Streets </li></ul><ul><li>Exposed Soils </li></ul><ul><li>Patios, porches and decks </li></ul><ul><li>Foundation walls </li></ul><ul><li>Brick work – walls and chimney </li></ul>
    33. 39. Good <ul><li>From the Colorado Geological Survey, Special Publication 43, Figure 37, p. 64 </li></ul>
    34. 40. Bad <ul><li>From the Colorado Geological Survey, Special Publication 43, Figure 37, p. 64 </li></ul>
    35. 41. Inspection - Resale <ul><li>Interior walls </li></ul><ul><li>Doors and windows </li></ul><ul><li>Floors and ceilings </li></ul><ul><li>Basement/Crawl space </li></ul><ul><li>Utility pipes </li></ul><ul><li>Furnace </li></ul><ul><li>Sump </li></ul>
    36. 42. Inspection – New Homes/Properties <ul><li>Soil report </li></ul><ul><li>Hire someone to interpret the report and review design/workmanship. </li></ul><ul><li>3 questions </li></ul><ul><ul><li>Is there swelling soils beneath the house? </li></ul></ul><ul><ul><li>If so, what is the degree or Potential? </li></ul></ul><ul><ul><li>Designed AND built with proper consideration for actual soil conditions? </li></ul></ul>
    37. 43. Risk <ul><li>Disclosure </li></ul><ul><li>Presence and potential severity </li></ul><ul><li>Design and construction methods </li></ul><ul><li>Damage and/or repairs (inspect) </li></ul><ul><li>The Final Decision </li></ul>