Permeable Pavements

1. Permeable Pavements Shingle Creek Watershed Management Commission May 31, 2011

3. Outline • Purpose of presentation • Types of pavements and applications • Benefits • Design considerations • Maintenance considerations • Example projects • Questions

5. Types of Permeable Pavements • Porous Asphalt • Pervious Concrete • Pervious Pavers Permeable pavement has pores or openings that allow water to pass through the surface and stone base material and infiltrate into the underlying soils.

6. Porous Asphalt Pervious Pavers Pervious Concrete

7. Pervious Pavement Hydrology

8. Porous HMA (or Dense HMA with Piping)

9. John Barten, second from right, riding on pervious pavement in Medina around 1905.

10. Water Storage in Pervious Concrete System

11. Porous Asphalt Section

12. Pervious Concrete Paver

13. Project Applications • Streets • Parking lots • Sidewalks and paths • Driveways • Patios • Playgrounds

14. Potential Benefits • Reduces the rate and quantity of stormwater runoff • Reduces stress on the sewer system • Recharges groundwater • Filters out silt, pollutants, and debris • Maintains natural drainage paths • Reduces standing water nuisance

15. Potential Benefits • Reduces stormwater infrastructure needs (pipes, ponds, catch basins) • Offers good alternative to conventional stormwater mitigation • Better erosion control • Reduces ice buildup and need for salting during the winter • Provides better traction

16. Design Considerations • Soils • Depth to groundwater • Traffic loading • Slopes • Blowing dust and debris

17. Design Considerations • Unique site features • Agency stormwater regulations • Frost penetration

18. Permeable Pavement Limitations Use of permeable pavement is not recommended in the following cases: • Industrial “brownfield sites or sites with contaminated soils • Where site layouts direct clogging sediment on the pavement surface • Sites with excessively steep grades

19. Maintenance Considerations • Protect pavement from silt and sediment during and after construction • Vacuum sweep at least twice a year • Do not seal coat • Do not sand • Use caution when snowplowing • Post signs advising maintenance crews

20. Maintenance Considerations • Perform periodic inspections; look for clogging, raveling, cracking, and wear • Other???

21. Ongoing Maintenance -Vacuum Sweeping

22. Sweepings

23. Maintenance Warning Signs

24. Paired Intersection Study, Robbinsdale, MN Porous asphalt test section - Abbott/41st , 2009

25. Porous Subgrade Preparation

26. Porous Asphalt Placement

27. Cost • Test section = 150 feet long, 27 feet wide • Traditional pavement, contract unit prices = $14,125 =$32/SY • Porous pavement • Site 1 = $42,670 • Site 2 = $32,200 • “Upcost” = $35-50/SY

28. Residential Street Paving Project, Shoreview, MN Lake Owasso Asphalt replaced with pervious concrete, 2009

29. Water Infiltration Demohttp://www.youtube.com/watch?v=j_z0xRPbExY

30. Shoreview Water Infiltration Demo

31. Pervious Concrete Cost Comparison Common Excavation – 11,000CY($6.00/CY) = $ 66,000* Fabric – 11,000SY($1.00/SY) = $ 11,000 1-1/2” Crushed Rock – 5000CY($52.00/CY) = $260,000* 7” Pervious Concrete – 8470SY($46.50/SY) = $394,000 Total Cost for Pervious Concrete System = $731,000 Per SY Cost for Pervious Concrete System = $ 86.30** *Average depth beneath concrete = 1.75-feet Estimated Bituminous Road Cost = $257,000 Estimated Underground Infiltration Cost = $417,500 Total Est Cost – Bit Road & Infiltration = $674,000 Per SY Est Cost – Bit Road & Infiltration = $ 79.60** **8.5% Increased Cost for Pervious Concrete

32. Wolner Field Parking Lot, Mound, MN Before After Asphalt replaced with pervious concrete and draintile, 2007

34. Pavement Cost Comparison

35. Mound Transit Center, Mound, MN Installed pervious pavers, 2007

36. Subgrade preparation

38. Little Six Casino, Prior Lake, MN Porous asphalt pavement in parking lot, 2009

39. Brainerd Area Porous asphalt parking lot, 2006