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Minnesota Wildfire Hazard Assessment System

Minnesota Wildfire Hazard Assessment System. Fuel Reduction Activities. Bad Situation. 911 Call: Small fire in the woods near a house. Fire in the woods!. FIRE!. Only Got Worse. The Home Ignitability Zone. It’s what happens in the home ignitability zone that’s important

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Minnesota Wildfire Hazard Assessment System

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  1. Minnesota Wildfire Hazard Assessment System

  2. Fuel Reduction Activities

  3. Bad Situation 911 Call: Small fire in the woods near a house Fire in the woods! FIRE!

  4. Only Got Worse

  5. The Home Ignitability Zone • It’s what happens in the home ignitability zone that’s important • If it’s connected to the structure, it’s part of the structure • Little things matter in defending against firebrands

  6. Home Ignition Zone 100 feet

  7. Home Ignition Zone

  8. Home Ignition Zone

  9. Luck (defn.): the events or circumstances that operate for or against an individual

  10. Hazard Assessment Process • Select the areas to be evaluated • Select the hazard components to be considered • Score the hazard components • Compile the hazard ranking in a usable format (database) • Develop future actions / projects

  11. GIS Systems • Satellite-based imagery • Fuel hazard types

  12. GIS Systems Look at fuels close to buildings • Identify the degree of defensible space between the building outline and the surrounding trees

  13. GIS Systems Using the data created in phase 1 & the power of either ArcView or EPIC • Run an analysis with an Hazard Fuel layer to locate the highest risk areas

  14. GIS Systems

  15. FIREPRONE NEIGHBORHOOD

  16. Hazard Assessment Form Starting with the highest risk areas, do a site visit and check for: • Subdivision Design • Site Hazards • Structural Hazards

  17. Rating Factors • Vegetation • Structure • Location

  18. 1. ACCESS • IF 1 primary & one secondary access 3 • IF 1 access road in & out 5

  19. 2. PRIMARY ROAD WIDTH • At least 20 feet wide 1 • Less than 20 feet wide 3

  20. 3. SECONDARY ROAD CHARACTERISTICS • Structure on main access road 0 • Road ends in a cul-de-sac • Cul-de-sac diameter more than 100 feet 1 • Cul-de-sac diameter less than 100 feet 2 • Dead end road less than 200 feet 3 • Dead end road more than 200 feet 5

  21. 4. STREET SIGNS • Present (> 4” and reflectorized) 1 • Missing (< 4” or non-reflectorized) 3

  22. 5. DRIVEWAY LENGTH • Less than 150 feet long 0 • Greater than 150 feet with minimum 3 45 foot outside radius turnaround • Less than 150 feet with small 5 or no turnaround

  23. 6. DRIVEWAY WIDTH • More than 12 feet wide 0 • Less than 12 feet 5 • No obstructing branches (up to 14 feet) 0 • Obstructing overhead branches 5 • Inadequate surface for heavy vehicles add5

  24. 7. DRIVEWAY SLOPE • Level or driveway length less than 30 feet 0 • Steep driveway (over 10%) 5

  25. 8. GATED / LOCKED • No 0 • Yes 2

  26. 9. ADDRESS • Not visible from road 2

  27. 10. FUEL TYPES • Deciduous, hardwoods 1

  28. 10. FUEL TYPES • Mixed (Hardwoods and Conifers) 5

  29. 10. FUEL TYPES • Conifer (Pine, spruce, red-cedar) 10

  30. 11. DEFENSIBLE SPACE • Good thinning out 70 feet from buildings 1

  31. 11. DEFENSIBLE SPACE • Only 30 foot around buildings treated 5

  32. 11. DEFENSIBLE SPACE • No defensible space treatment 10

  33. 12. LADDER FUELS • Underbrush and low branches present 5 • No branches within 6 feet of the ground 0

  34. 13. TYPE OF GROUND COVER • Sand, gravel 0 • Grasses up to 6 inches tall 2 • Grasses 6-12 inches tall 5 • Marsh or grasses > 12 inches tall 6 • Shrubs with leaves 3 • Shrubs with needles 4 • Moderate to heavy slash 7 MAJORITY OF TYPE COVERAGE WITHIN 30 FEET OF STRUCTURES

  35. 14. SLOPE OF PROPERTY • Flat (0-5%) 0 • Moderate (6-20%) 2 • Steep (over 20%) 4

  36. 15. FIREWOOD STORAGE • 0 to 20 feet from structure 5 • 20 feet from structure & <25’ from edge 3 • 20 feet from structure & >25’ from edge 1 • No outside stored firewood 0

  37. 16. OUTBUILDINGS • None, or more than 25 ft away 0 • Within 25 feet of home 3

  38. 17. POWERLINES • Underground or clear of trees 0 • Trees too close, can fall on lines 3

  39. 18. WATER SOURCE • Hydrant within 1000 ft of structure 0 • No hydrant, draft source within 1000 ft 1 • Water source -- < 20 minute round trip 4 > 20 minute round trip 6

  40. 19. ROOFING MATERIALS • Metal, tile or fiberglass (good condition) 0 • Asphalt shingles / rolled roofing 3 • Wood shingles 6 • Flat roof add 1

  41. 20. SOFFITS & ATTIC VENTS • Enclosed with metal screens 0 • Enclosed with plastic screens 2 • Unscreened vents 4

  42. 21. WINDOWS • Small (<5x5) 0 • Large 2

  43. 22. FOUNDATION • Open 5 • Enclosed with wood sheeting 3 • Enclosed with fireproof sheeting 0

  44. 23. EXTERIOR WALL MATERIALS • Brick / stone / metal 0

  45. 23. EXTERIOR WALL MATERIALS • Vinyl / wood 4

  46. 24. DECKS AND OVERHANGS • No deck, no open overhang or attached fence 0 • Non-combustible siding AND deck 1 • Combustible siding OR deck 4 • Combustible siding AND deck 10

  47. Home Wildfire Risk Calculation • Subdivision Design (A) 11 • Site Hazards (B) 59 • Structural Hazards (C) 18 • TOTAL 88

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