Edison Environmental Center
GREEN INFRASTRUCTURE RESEARCH PROGRAM
Providing Research Solutions to Manage Wet-Weather Flow
Porous Pavement
Introduction
Porous pavement provides stormwater
runoff reduction through infiltration.
In a porous pavement system,
stormwater runoff moves through
several layers of bedding after passing
through the porous surface and
infiltrates into the subgrade soil.
Some pollutants may be removed as
the water moves through the
underlying materials. The most
commonly-used permeable surfaces
are porous asphalt, porous concrete,
and interlocking concrete pavers,
which are often called porous pavers
although the pavers themselves are
not porous. Porous pavement systems
can reduce the impact of stormwater
on receiving waters by reducing
runoff volumes and decreasing and
delaying peak flows. Porous
pavement systems serve two low-
impact development purposes as they
both reduce impervious area and
infiltrate stormwater runoff.
Background
The National Risk Management
Research Laboratory (NRMRL) is
evaluating porous pavement as part of
a larger collection of long-term
research examining multiple
stormwater management practices.
The U.S. EPA recognizes the
potential of porous pavement systems
as a green infrastructure management
tool to lessen the effects of peak flows
on aquatic resources.
While the installation of porous
pavement systems has become more
prevalent, there is a lack of full-scale,
outdoor, real-world porous pavement
research with system replicates. More
studies of porous pavement operating
in its intended use (parking lot,
roadway, etc.) with climatic events,
regular use, and maintenance effects
are necessary.
Objectives
The Green Infrastructure Research
Program's long-term porous
pavement research addresses several
objectives. The overall objective of
the project is to document the
performance and capabilities of three
porous pavement systems
simultaneously at the same site with
replicates that allow for statistical
analyses. The parking lot will be
monitored for hydrologic
performance, water quality
performance, urban heat island
mitigation, maintenance effects, and
parking behavior in the lot.
Current Research
The experimental design of the
parking lot is shown in Figure 1. There
are five parking rows in this 110-
parking space lot and four of them are
instrumented for long-term
monitoring. Moving from north to
south, the parking row surfaces are:
porous concrete (not monitored),
National Risk Management
Research Laboratory
www.epa.gov/nrmrl
interlocking concrete pavers, porous
concrete, porous asphalt, and
conventional asphalt. The porous
concrete parking row at the northern
end of the lot is necessary to ensure
that each of the monitored sections
receives runoff from the same
drainage area. The order of the porous
surfaces was chosen randomly. The
runoff generated by the conventional
asphalt at the southern end of the
parking lot will feed the rain gardens
via curb cuts and will also serve as an
experimental control. The roof runoff
from an adjacent building will also be
piped to the rain gardens, so as not to
add runoff to the parking lot. Each of
the monitored porous pavement
parking rows has subsections lined
with an impermeable geotextile fabric
to collect the infiltrating water as well
as sections that infiltrate into the
underlying soil. There are four
impermeable (darker sections of each
parking row) and five permeable
sections (lighter sections of each
parking row) for each porous
pavement type, which allows for
statistical analyses of data. Each
impermeable section has a perforated
pipe that drains the accumulated
runoff through pipes under the
roadway to a dedicated collection
tank on the eastern side of the lot;
consequently, there are a total of
twelve storage tanks.
U.S. Environmental Protection Agency
Office of Research and Development
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Plan view
I
c
c
c )
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1.1
Interlocking concrete pavers | [Porous concrete | [Porous asphalt [^[Conventional asphalt
distribution pipes
ICollection tanksURain gardens | [Tree islands
Figure 1. Plan view of the porous pavement parking lot at the Edison Environmental Center. (After Morris Ritchie and
Associates, 2009)
The unlined sections at the ends of
each monitored porous surface
parking row will allow for the
monitoring of the interaction of the
infiltrated water with the subgrade
soil. The unlined sections are
instrumented with permanent
equipment as well as access pipes that
allow for the placement of
instruments for event-based sampling.
The instruments in the unlined
sections will monitor accumulated
water depth, wetting front passage,
and temperature throughout the
porous pavement profile. The lined
parking sections are not instrumented,
but the infiltrating water will be
collected via the buried distribution
pipes and will allow for the
measurement of infiltrated water
volume, rate of infiltration, and
analysis of selected water quality
parameters including: solids,
microbes, nutrients, metals, and semi-
volatile organic compounds.
Impacts
The parking lot at the Edison
Environmental Center will permit the
investigation of a number of topics
relative to the design and performance
of porous pavement systems. The
project is unique, not only due to the
three side-by-side permeable surfaces
but also because of the planned long-
term monitoring, the extent of the
installed instrumentation, the scale,
the division of the parking rows for
replicates, and the direct monitoring
of volume and flow rate.
Measurements will be taken under
controlled conditions while the lot is
actively used for employee parking.
The porous pavement parking lot is a
demonstration site that will be used as
an educational tool to show how
porous pavement works. It will also
contribute to "greening" the EPA's
Edison facility and will illustrate that
porous pavement can provide
effective stormwater management.
The results of this study will provide
much needed design and performance
information to the regulated
community to enable better decisions
associated with their stormwater
management programs.
Contact
Michael Borst
Chemical Engineer
U.S. Environmental Protection Agency
Office of Research and Development
National Risk Management Research
Laboratory
732-321-6631
borst.mike@epa.gov
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