Permeable Paving
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Transcript of Permeable Paving
Permeable Paving
Low Impact Development (LID) Low impact development (LID) is an
approach to managing stormwater runoff to protect water quality
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
Non-Permeable Pavements Increased runoff Deprives groundwater Pollutants
Non-point source
Non-Permeable Pavements 1990s average was about 30,000 miles of
paving per year Parking lots affect microclimates of city
climates
Non-Permeable Pavements U.S. federal law mandates that states control
water pollution in runoff through the National Pollutant Discharge Elimination System (NPDES)
Increases the water quality Increases groundwater Reduces installation costs of drainage system Reduces storm water runoff Reduces flooding Reduces erosion
Advantages of Permeable Pavers
Permeable pavers PICP (also called permeable segmental
pavers) are non-porous, solid blocks made of brick, stone, clay or concrete
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
Permeable pavers No sand used in joints
Clog pores
Permeable pavers http://www.youtube.com/watch?v=xBTYFo2z9
HY&feature=related
Permeable pavers Cleaning should be done at least once a year Removed by a vacuum-sweeping street
cleaning machine
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.
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
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.
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 http://www.youtube.com/watch?v=ScsQYHMfabU
Pervious Asphalt and Concrete Ice doesn’t normally
form in the paving or on the surface
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
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
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
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.
POROUS ASPHALT Beneath its surface, underlying stone
reservoir that then filters water directly into the underlying soil, or storm-drain system
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
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
Cool asphalt Increase
pavements reflectiveness Albedo
Asphalt can be lightened
Asphacolor Colored at plant
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 25-35% Runoff coefficient close to
zero Underlying stone reservoir
PERVIOUS CONCRETE Porous concrete withstands heavier and more
repeated loads than porous asphalt Does not soften under heat
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
http://www.youtube.com/watch?v=wx-CNC7f5xY
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
Grass Pave Overflow parking
Grass Pave Fine gravel, oyster shells, or other permeable
material can substitute for grass for more frequent parking
Grass Pave Use mix of sand and water polymers
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 $10.00 per square foot
Green Streets Manage water at source Infiltrate water where it hits the ground Reduce downstream flows by at least 80%
Manage water at the surface Allow for evapotranspiration
Assets Aesthetically pleasing