HomeMy Public PortalAboutPorous Pavement Brochure2015Metropolitan St. Louis Sewer District Web Site: www.stlmsd.com 24-Hour Hotline 314.768.6260 Metropolitan St. Louis Sewer District
Owner’s Guide for General Inspection
& Maintenance Activities
General Inspection and Maintenance
Inspect after major storms: Check for standing water
on the pavement after rainfall. If standing water
remains 30 minutes after rainfall has ended, cleaning
is recommended.
Clean clogged areas: Vacuuming and power washing
can be effective.
Remove unwanted vegetation: Weeds should first be
sprayed with herbicide and then pulled within the
week. If unwanted vegetation persists, it becomes
harder to remove the root and removal can be more
destructive to the structure of the pavement. Note:
Some permeable applications are meant to be
grassed, for which mowing may be appropriate. Be
sure to catch grass clippings to avoid accumulation.
Repair damage to asphalt: Damaged areas may be
repaired using infrared heating and rerolling pavement.
Most damage can be repaired using standard asphalt,
presuming repairs don’t exceed 15% of the total area.
Check adjacent areas: It’s important to control erosion
and sedimentation in adjacent areas. Vacuuming
adjacent non porous asphalt can be effective at
minimizing run-on.
Storage uses: Do not store sand, salt, mulch, soil, yard
waste, snow, or other stock piles on porous surfaces.
Stain Removal: Stain remover can be applied before
power washing. Power washing should only be
conducted at a rate that will not damage pavement.
Any removed fill aggregate should be replaced.
Post signage: It’s recommended to post a sign at the
site indicating the presence of porous pavement.
Signage should display the design load (i.e.,
passenger vehicles only, light truck traffic).
Owner’s Guide for General Inspection
& Maintenance Activities
Spring and Summer Months
Keep pavement free of leaves and lawn waste.
Retain sweeping professional to remove fine
sediments from paver surface to optimize permeability.
At a minimum, pavement should be vacuumed during
spring following the last snow to remove accumulated
debris.
Fall and Winter Months
Promptly remove snow and ice from the pavement. Be
careful to not damage pavement with blade. Rubber
tips or lifting blade to avoid scraping pavement is
recommended.
Do not use sand for snow or ice treatment.
Retain sweeping professional to remove fine
sediments from paver surface to optimize permeability.
At a minimum, pavement should be vacuumed during
spring following the last snow to remove accumulated
debris.
Importance of Regular Maintenance
The best way to keep maintenance costs of the porous
pavement low is to follow manufacturer
recommendations for regular maintenance. Most
manufacturers recommend that the pavement be
vacuumed at least twice a year. Some case studies
have shown that porous pavement can lose its efficacy
in as little as a year if it goes without vacuuming.
Maintenance Costs
A general rule of thumb to estimate annual maintenance
costs is to use 3-6% of the construction costs of the post
construction stormwater BMP. Ensuring routine
preventative maintenance is completed on a routine
basis, will help deter higher costs associated with non-
routine restorative maintenance. As more post
construction stormwater BMPs are installed and
operative, more data on maintenance costs will become
available locally and nationally.
References
MSD BMP Toolbox
http://www.stlmsd.com/what-we-do/stormwater-
management/bmp-toolbox/stormwater-
quality/permeable-pavement
United States Environmental Protection Agency
http://water.epa.gov/polwaste/npdes/swbmp/Porous-
Asphalt-Pavement.cfm
Concrete Answers Series
http://www.perviouspavement.org/index.html
Metropolitan St. Louis Sewer District
Division of Environmental Compliance
10 East Grand Avenue
St. Louis, MO 63147-2913
Phone: 314.768.6260
www.stlmsd.com
Your MSD @yourMSD
Porous Pavement
Post-Construction Stormwater
Best Management Practice (BMP)
• What is porous pavement?
• Types & benefits of porous pavement
• Inspection & maintenance
Metropolitan St. Louis Sewer District Web Site: www.stlmsd.com 24-Hour Hotline 314.768.6260 Metropolitan St. Louis Sewer District
What is Porous Pavement?
Porous pavement, also known as pervious or
permeable pavement, is a pavement surface that is
specially designed to mimic the way that natural land
absorbs water. Although sometimes nearly
indistinguishable in appearance from traditional
paving materials, porous pavement contains
openings or pores that make it possible for it to soak
up stormwater. An underlying stone bed then
temporarily stores the water before it infiltrates into the
subsoil or released back to the storm sewer through
the underdrain. While this BMP can be applied as an
automobile and pedestrian traffic surface, it performs
best when used on sidewalks, driveways, alleys,
parking lots, patios and other low-traffic/low-speed
applications to minimize clogging, cracking and
rutting of the surface. To enable porous pavements
to function as intended, however, inspection and
consequent maintenance are imperative.
http://www.crwa.org /projects/bmpfactsheets/crwa_permeable_pavers.pdf
Types of Porous Pavement
Porous Concrete – Porous concrete is composed of
the same components as traditional concrete, which
are sand, gravel/crushed stone, cement and water.
Less sand is used for the porous concrete mixture to
increase pore space on the surface. Porous concrete
contains stable air pockets that enable water to drain
through it. Porous concrete is slightly rougher than
conventional concrete on the surface.
Porous Asphalt -- Porous asphalt is typically
standard hot-mix asphalt that contains less sand than
traditional asphalt. Like porous concrete, it also
contains air pockets that allow water to seep through
it. Porous asphalt is commonly lighter in color than
conventional asphalt and cooler during hot weather.
Types of Porous Pavement
Permeable Pavers -- Permeable pavers are modular
systems of interlocking blocks of concrete or other
strong structural material that are designed with
small, regularly spaced openings. These open spaces
typically are filled with soil, grass, or gravel that soak
up stormwater before it infiltrates to the aggregate
bedding layer that sits below and supports the pavers.
Permeable
interlocking
concrete
pavers
(PICP)
Concrete
grid pavers
(CGP)
Plastic
reinforcing
grids (PG)
filled with
gravel
Plastic
reinforcing
grids (PG)
with grass
Porous Pavement Inspection &
Maintenance Requirements
Inspections and maintenance by the owner are critical
to porous pavement’s operation and longevity. Specific
maintenance needs may vary depending on storm
frequency, season changes, and traffic conditions. As a
result, planning for maintenance may differ between
types of systems.
Inspection & Maintenance Activities
Inspection
Visual and physical inspections are integral to porous
pavement operation and maintenance. The visual
inspection includes monitoring pavement to check for
water drainage, debris accumulation, and surface
deterioration. If a pervious surface is not properly
maintained, it will become clogged, diminishing its life
expectancy and ability to infiltrate stormwater.
Sediment accumulation and vegetative life are the most
common causes of clogging.
Maintenance Activities - Street Sweeping
Street sweeping is an important maintenance task
associated with porous pavement. Street sweeping can
serve one of two purposes: preventative maintenance
and restorative maintenance. It is important to note that
when street sweeping is conducted for porous paver
systems, any fill aggregate removed should be
replaced to avoid creating a tripping hazard. Sweeping
the pavement 2-4 times per year is sufficient for
maintaining permeability. There are three main types of
street sweepers:
• Mechanical
Mechanical street sweepers employ a multiple brush
approach to first move sediment and trash to the middle
and then lift the deposits onto a conveyor belt for
temporary storage. The brush bristles can penetrate some
types of permeable pavements, but not all of them.
• Regenerative Air
Regenerative air street sweepers work by shooting air at
an angle to the pavement, which effectively loosens dust
and particles at and near the surface of the pavement.
With this, a minor vacuum is created which lifts loosened
particles into a hopper. This system is capable of removing
surface-deposited sediments from all pavement types.
This type of sweeper is recommended for use for
preventative maintenance for all three types of porous
pavements.
• Vacuum
Vacuum sweepers apply a strong vacuum to a relatively
narrow area that lifts particles both at and below the
surface of the pavement. They are recommended for use
as restorative maintenance considering they have the
ability to suction 3 to 4 inches of gravel from pavers.