Permeable Pavements

Shingle Creek Watershed Management Commission May 31, 2011

Outline

       Purpose of presentation Types of pavements and applications Benefits Design considerations Maintenance considerations Example projects Questions

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.

Porous Asphalt Pervious Concrete Pervious Pavers

Pervious Pavement Hydrology

Porous HMA (or Dense HMA with Piping)

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

Water Storage in Pervious Concrete System

Porous Asphalt Section

Pervious Concrete Paver

Project Applications

      Streets Parking lots Sidewalks and paths Driveways Patios Playgrounds

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

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

Design Considerations

     Soils Depth to groundwater Traffic loading Slopes Blowing dust and debris

Design Considerations

   Unique site features Agency stormwater regulations Frost penetration

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

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

Maintenance Considerations

  Perform periodic inspections; look for clogging, raveling, cracking, and wear Other???

Ongoing Maintenance Vacuum Sweeping

Sweepings

Maintenance Warning Signs

Paired Intersection Study, Robbinsdale, MN

Porous asphalt test section - Abbott/41st , 2009

Porous Subgrade Preparation

Porous Asphalt Placement

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

Residential Street Paving Project, Shoreview, MN

Lake Owasso Asphalt replaced with pervious concrete, 2009

Water Infiltration Demo http://www.youtube.com/watch?v=j_z0xRPbExY

Shoreview Water Infiltration Demo

Pervious Concrete Cost Comparison

Common Excavation – 11,000CY($6.00/CY) Fabric – 11,000SY($1.00/SY) 1 1/2” Crushed Rock – 5000CY($52.00/CY) 7” Pervious Concrete – 8470SY($46.50/SY)

Total Cost for Pervious Concrete System Per SY Cost for Pervious Concrete System

*Average depth beneath concrete = 1.75-feet = $ 66,000* = $ 11,000 = $260,000* = $394,000

= $731,000 = $ 86.30**

Estimated Bituminous Road Cost Estimated Underground Infiltration Cost

Total Est Cost – Bit Road & Infiltration Per SY Est Cost – Bit Road & Infiltration **

8.5% Increased Cost for Pervious Concrete = $257,000 = $417,500

= $674,000 = $ 79.60**

Wolner Field Parking Lot, Mound, MN Before After

Asphalt replaced with pervious concrete and draintile, 2007

Pavement Cost Comparison

Mound Transit Center, Mound, MN

Installed pervious pavers, 2007

Subgrade preparation

Little Six Casino, Prior Lake, MN

Porous asphalt pavement in parking lot, 2009

Brainerd Area Porous asphalt parking lot, 2006

• You've carefully thought out all the angles. • You've done it a thousand times.

• It comes naturally to you.

• You know what you're doing, its what you've been trained to do your whole life.

• Nothing could possibly go wrong, right ?