1. Permeable Paving

2. Low Impact Development (LID)
Low impact development (LID) is an approach to managing stormwater runoff to protect water quality

3. Permeable Pavements
Permeable pavements are recognized as a Best Management Practice (BMP) by the U.S. Environmental Protection Agency
A cornerstone of low impact development (LID) design

4. Non-Permeable Pavements
Increased runoff
Deprives groundwater
Pollutants
Non-point source

5. Non-Permeable Pavements
1990s average was about 30,000 miles of paving per year
Parking lots affect microclimates of city climates

6. Non-Permeable Pavements
U.S. federal law mandates that states control water pollution in runoff through the National Pollutant Discharge Elimination System (NPDES)

7. Advantages of Permeable Pavers
Increases the water quality
Increases groundwater
Reduces installation costs of drainage system
Reduces storm water runoff
Reduces flooding
Reduces erosion

8. Permeable pavers
PICP (also called permeable segmental pavers) are non- porous, solid blocks made of brick, stone, clay or concrete

9. Permeable pavers Initially, infiltration is over 50-75in/hr.
Reduce by around 50% in the first 5 years.
Over a 20-year period, PICP’s are designed to achieve and maintain a consistent 3in/hr infiltration rate

10. Permeable pavers
No sand used in joints
Clog pores

11. Permeable pavers
e=related

29. Permeable pavers Cleaning should be done at least once a year
Removed by a vacuum-sweeping street cleaning machine

30. Permeable interlocking concrete pavements
A North Carolina State University study has shown that the initial surface infiltration rate of PICPs can be as high as 2,000 in./hour. Other research has shown that near initial surface infiltration rates can be restored through cleaning and replacement of the initial 3/4 to 1 in. depth of small stones in the openings of PICPs.

31. Permeable interlocking concrete pavements
Ice and snow can melt into the pavement
Water does not collect on the surface and re-freeze
Reduces slipping hazards

32. Permeable interlocking concrete pavements
Sand should not be used for traction
Deicing salts can
Adequate space for the ice to expand within the open- graded base
Minimizing the risk of heaving.

33. Pervious Asphalt and Concrete
Stone aggregate is held together with either asphalt or cement
Angular crushed stone, usually 3/8”, excluding fines that normally fill voids
Porous

34. Pervious Asphalt and Concrete
Ice doesn’t normally form in the paving or on the surface

35. Pervious Asphalt and Concrete
Pervious paving may cost 10% more than conventional asphalt
Doubling as a stormwater system and eliminating storm drains, save 12% to 38%
Reduces retention ponds
Land area saved that would be used for basins

36. Pervious Asphalt and Concrete
Snow melts quickly and drains
Soil around any porous installation must percolate minimum rate ½” per hour
Contain no more than 30% clay

37. Pervious Asphalt and Concrete
Most researchers found that proper design, installation and maintenance can prevent loss of porosity over time
Minor loss of porosity occurs in all porous materials over the first four to six years
One test, an inch of loose fine was applied
Full porosity was easily restore by a cleaning with a HydroVac

38. POROUS ASPHALT
Formulated with larger aggregate and less fine particles
“Open-graded” surface drains and supports traffic
Single-sized aggregate particles leave open voids (typically between 25-35%) that give the material its porosity and permeability.

39. POROUS ASPHALT
Beneath its surface, underlying stone reservoir that then filters water directly into the underlying soil, or storm- drain system

40. POROUS ASPHALT
Asphalt version originally developed for airport runways
prevents dangerous surface ponding
Reservoir supports the porous surface and hold precipitation until it can percolate into the soil
Shallow as nine inches on some well-drained soils

41. POROUS ASPHALT
Using crushed rock open graded to about two inches in size, almost 40% of the reservoir’s total volume will be waterholding voids
Choker course of half inch gravel is laid on top

42. Cool asphalt Increase pavements reflectiveness
Albedo
Asphalt can be lightened
Asphacolor
Colored at plant

43. PERVIOUS CONCRETE Grainier and less smooth than traditional concrete
Controlled amounts of water and cement materials bound with large aggregate particles
Contains little or no fines
Substantial void space between %
Runoff coefficient close to zero
Underlying stone reservoir

44. PERVIOUS CONCRETE
Porous concrete withstands heavier and more repeated loads than porous asphalt
Does not soften under heat

45. Grass Pave Grass will not survive daily traffic
Grass for parking stays healthy if used not more than about one day a week, less in dry climates

46. GRASS PAVERS
Open-cell unit paver in which the cells are filled with soil and filled with turf or gravel
Comprised of a grid system, which is made of concrete or synthetic to distribute the weight of traffic
Appropriate for
Foot traffic
Overflow parking
Driveway

47. Grass Pave
Overflow parking

48. Grass Pave
Fine gravel, oyster shells, or other permeable material can substitute for grass for more frequent parking

49. Grass Pave
Use mix of sand and water polymers

50. COST COMPARISON Asphalt: $0.50 to $1 per square foot
Grass/Gravel Pavers: $1.50 to $5.75 per square foot
Porous Concrete: $2.00 to $6.50 per square foot
Interlocking Concrete Paver Blocks: $5.00 to $ per square foot

51. Green Streets Manage water at source
Infiltrate water where it hits the ground
Reduce downstream flows by at least 80%

52. Manage water at the surface
Allow for evapotranspiration

53. Assets
Aesthetically pleasing