science in ACTION
INNOVATIVE RESEARCH FOR A SUSTAINABLE FUTURE
c/EPA
www.epa.gov/research
Green Infrastructure Research: Permeable Pavement at
EPA's Edison Environmental Center
•	Three types of surfaces:
o Permeable interlocking concrete paver
o Pervious concrete
o Porous asphalt
•	Instrumented to monitor:
o Infiltrating water and interaction with underlying soil
o Surfaces' ability to accept water
o Water quality
o Usage and maintenance effects
•	Lined and unlined sections for capture and monitoring of infiltrating water
•	Conventional asphalt driving lanes to allow for runoff to permeable surfaces
•	Runoff from conventional asphalt at south end feeds rain garden
•	Surfaces are exposed to the same conditions for direct comparison
Background
Stormwater runoff from urban or
paved areas can pollute receiving
waters and cause flooding and
erosion. A type of green
infrastructure, permeable pavement
systems reduce runoff volumes by
allowing stormwater to drain
tlirough a paved surface, recharging
groundwater supplies. Pollutants
may be removed as the water moves
tlirough the underlying materials.
While the number of permeable
pavement systems is growing, there
is a lack of research on side-by-side
comparisons of full-scale, outdoor
systems that are actively-used.
Studies of permeable pavement
operating in its intended use are
necessary to determine performance,
required operations and
maintenance, and water quality
impacts.
Research Objective
EPA scientists are evaluating
permeable pavement as part of a
long-term research effort examining
stormwater management practices.
The objective of the research is to
simultaneously demonstrate and
document the performance and
capabilities of three permeable
pavement systems: permeable
interlocking concrete pavers (PICP),
pervious concrete (PC), and porous
asphalt (PA); and determine water
quality impacts.
Approach & Methods
In 2009, EPA installed a permeable
pavement parking lot at its Edison
Environmental Center in New
Jersey. The lot, designed to be
monitored as a long-term research
effort, is in regular use by facility
Figure 1. Aerial view of EPA's Edison Environmental Center permeable
parking lot: (A) permeable interlocking concrete pavers, (B) pervious
concrete, (C) porous asphalt, (D) conventional asphalt.
Figure 2. Key permeable parking lot design features at EPA's Edison
Environmental Center.
staff and visitors. The 43,000 sq. ft.
parking lot lias three types of
permeable surfaces across 110 stalls
in five rows (Figure 1). Figure 2
summarizes the lot's key features.
Each of the permeable parking rows
lias sections with impermeable liners
to collect the infiltrating water and
pipes that transport it to a collection
tank. Unlined sections allow
stormwater to infiltrate to the
underlying soil, and instruments
monitor accumulated water depth
movement, and temperature.
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U.S. Environmental Protection Agency
Office of Research and Development
EPA/6Q0/F-16/131
November 2016

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Table 1. Key research results from EPA's Edison Environmental Center permeable parking lot.
Monitoring Objective
Parameters Measured
Key Results
Hydrologic performance
Volume, exfiltration rate,
infiltration rate (IR)
•	PC has largest infiltration rate; PA has lowest.
•	Infiltration rate decreases with increasing thickness.
Water quality
performance
Solids, indicator organisms,
metals, nutrients, semi-volatile
organic compounds
•	Permeable pavement systems do not reduce total nitrogen.
•	Total nitrogen concentration in PA infiltrate was higher than
rainfall, other surface infiltrate, or runoff concentration, a
finding unique to this study.
•	Orthophosphate concentration in infiltrate from PA was smaller
than in rainwater, runoff, and infiltrate from PICP and PC.
Urban heat island
effects
Net radiation, infrared radiation,
temperature
• 5 to 7% of infiltrate evaporates, which may help mitigate heat
island effects.
Maintenance effects
Surface infiltration rate, visual
assessment
•	Instruments monitor surface clogging and infiltration capacity,
providing insight as to when maintenance is needed.
•	Surface clogging occurs overtime as sediment in runoff blocks
infiltration pathways and reduces infiltration rates.
Use
Visual assessment
• PC breakdown (raveling) began occurring after five years.
Infiltrating water
parameters
Water depth, redox, pH,
conductivity, chloride
•	Chloride is trapped in pavement and flushed out over time,
persisting longest in PA and releasing fastest from PC.
•	Acidic rainwater became basic as it infiltrated through each
permeable pavement profile; PA infiltrate had highest pH.
Results
The performance of the systems
vary, and key research results are
summarized in Table 1. Despite
variation among pavement types,
any of these permeable pavements
should adequately infiltrate not only
direct rainfall but additional run-on
from adjacent areas (Brown and
Borst 2014).
Researchers observed effects on
water quality from nitrogen, and
from chloride, after road salt
application. PA infiltrate had a
larger total nitrogen concentration
than both runoff and infiltrate from
the other pavement types. This
indicates that nitrogen leached from
materials in this PA strata, a finding
unique to this study (Brown and
Borst 2015). After chloride (road
salt) application, some chloride is
temporarily trapped in the permeable
pavement surface and underlying
aggregate, but is flushed during
subsequent rainfalls. Chloride was
found in the infiltrate in measurable
amounts throughout the year, with
reported concentrations at levels
more than ten times the national
recommended aquatic life criterion
(Borst and Brown 2014). Chloride
was also attributed to the breakdown
of the PC.
Impact
The EPA Edison parking lot
facilitates the investigation of the
design and performance of
permeable pavement systems. This
research provides needed design
performance, and water quality
impact information to enable
communities to make better
stormwater management decisions.
This research confirms that all three
types of surfaces studied (PICP, PC,
and PA) are viable options for
infiltrating both rainfall and
stormwater run-on.
Decision makers have the challenge
of evaluating these benefits against
water quality impacts, which can be
significant. Increased nitrogen
released from PA can lead to
eutrophication in surface water
systems. The year-around release of
chloride from all permeable
pavement types causes elevated
levels in surface waters, which can
negatively affect aquatic species.
EPA is continuing to research and
communicate about permeable
pavement design performance, and
water quality impacts.
In addition to its use as a field
research site, the parking lot is used
as a demonstration site to teach
visitors about permeable surfaces. It
also contributes to EPA's greening
strategy to reduce the enviromnental
impact of the Agency's facilities and
operations.
References
Borst, M., andR. Brown. (2014).
"Chloride released from three
permeable pavement surfaces after
winter salt application." JA H'/t I.
50(1), 29-41.
Brown, R., andM. Borst. (2014).
"Evaluation of surface infiltration
testing procedures in permeable
pavement systems." J. Environ.
Eng., 140(3), 04014001.
Brown R., and M. Borst (2015).
"Nutrient infiltrate concentrations
from three permeable pavement
types." J. Environ. Manage., 164,
74-85.
Additional Information
EPA's Green Infrastructure
Research: epa.gov/water-
research/green-infrastructure-
research
Greening EPA: epa. gov/greeningepa
Contact
Michael Borst, EPA Office of
Research and Development
732-321-6631 | borst.mike@epa.gov
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U.S. Environmental Protection Agency
Office of Research and Development
EPA/600/F-16/131
November 2016

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