HomeMy Public PortalAboutFinal Draft Porous Pavement BrochurePorous Pavement
Post-Construction
Best Management
Practices (BMPs)
Ownership and
Maintenance
MSD Project Clear
Division of Environmental Compliance
10 East Grand Avenue
St. Louis, MO 63147-2913
Phone: 314.436.8710
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Maintenance Costs
To estimate annual maintenance costs, use 3-6%
of the construction costs of the post construction
stormwater BMP. Ensuring 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
operated, more data on maintenance costs will
become available locally and nationally.
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 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 10% 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).
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.
All photos by Megan Ross unless otherwise noted.
* PG photos from Low Impact Development Center
Cover photo by JJ Harrison
MSDProjectClear.org MSDProjectClear.org MSD Customer Service: 314.768.6260
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. Porous pavement
contains openings or pores that make it possible
for it to soak up stormwater. An underlying stone
bed temporarily stores the water before it
infiltrates into the subsoil or is released back to
the storm sewer through an 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, inspection
and consequent routine maintenance are
imperative.
Porous Pavement Inspection &
Maintenance Requirements
Inspections and maintenance by the owner are
critical to porous pavement’s performance and
longevity. If a pervious surface is not properly
maintained, it will become clogged, diminishing
its life expectancy and stormwater infiltration.
Specific maintenance needs may vary depending
on storm frequency, seasonal changes, and traffic
conditions. As a result, planning for maintenance
may differ between types of systems.
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 Pavement Inspection &
Maintenance Requirements Continued
Inspection
Inspections are integral to porous pavement
operation and maintenance. An inspection
includes checking for water drainage, debris
accumulation, and surface deterioration.
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. 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. This type of sweeper is
recommended for preventative maintenance.
Regenerative Air
Regenerative air street sweepers work by shooting
air at an angle to the pavement, which 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 can remove surface-deposited sediments
from all pavement types. This type of sweeper is
recommended for preventative maintenance for all
three types of porous pavements.
Vacuum
Vacuum sweepers apply a strong vacuum to a
narrow area that lifts particles both at and below the
surface of the pavement. They are recommended for
restorative maintenance considering they can
suction 3 to 4 inches of gravel from pavers.
Diagram from CRWA’s Permeable Pavers Information Sheet
PERMEABLE PAVERS
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.
Concrete grid pavers (CGP)
Plastic reinforcing grids (PG) filled with gravel*
PG filled with grass*
Permeable interlocking concrete pavers (PICP)
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.