Permeable Pavements Shingle Creek Watershed Management Commission May 31, 2011

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

Types of Permeable Pavements Porous Asphalt Porous Asphalt Pervious Concrete Pervious Concrete Pervious Pavers 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.

Pervious Pavers Porous Asphalt Pervious Concrete

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 Pervious Concrete Paver

Project Applications Streets Streets Parking lots Parking lots Sidewalks and paths Sidewalks and paths Driveways Driveways Patios Patios Playgrounds Playgrounds

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

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

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

Design Considerations Unique site features Unique site features Agency stormwater regulations Agency stormwater regulations Frost penetration Frost penetration

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

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

Maintenance Considerations Perform periodic inspections; look for clogging, raveling, cracking, and wear Perform periodic inspections; look for clogging, raveling, cracking, and wear Other??? 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 Test section = 150 feet long, 27 feet wide Traditional pavement, contract unit prices = $14,125 =$32/SY Traditional pavement, contract unit prices = $14,125 =$32/SY Porous pavement Porous pavement –Site 1 = $42,670 –Site 2 = $32,200 “Upcost” = $35-50/SY “Upcost” = $35-50/SY

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

Water Infiltration Demo Water Infiltration Demo

Shoreview Water Infiltration Demo

Pervious Concrete Cost Comparison Common Excavation – 11,000CY($6.00/CY) = $ 66,000* Fabric – 11,000SY($1.00/SY) = $ 11, /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 *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 **8.5% Increased Cost for Pervious Concrete

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