Evidence of this up-and-coming trend can be found in this
year's nationwide survey conducted by the American Society of
Landscape Architects (ASLA). Results of the survey indicated that
three of the top 10 trends in residential landscape design are per-
meable pavers, water-efficient irrigation, and rainwater/greywa-
ter harvesting.
"Right now, a lot of landscape contractors are just trying to
get their heads around designing systems to meet the new storm-
water requirements, and aren't thinking about rainwater harvest-
ing as part of it," said Joe Pierce of Hickory Hardscapes, which
recently installed a combined PICP/RWH system for a residential
client in Tennessee. "But it's a natural progression, and is a good
fit for a homeowner with the mindset to be self-sustaining."
Pierce's combined PICP/RWH residential project was origi-
nally planned as a standard permeable driveway, designed to al-
leviate potential flooding issues for a waterfront home built into
the side of a hill below the street level.
"I noticed that the homeowner had other elements to capture
rainwater, and suggested we do the same with the driveway," said
Pierce, who then designed and installed an RWH system, under
the driveway, that included a reservoir for collecting the water
and a pump for landscape irrigation.
EPA'S ROLE IN THE EMERGING PICP/RWH TREND
For several years, the U.S. Environmental Protection Agency (EPA)
has provided funding for states to finance projects that reduce pol-
www.landscapeirrigation.com Landscape and Irrigation November/December 2015 21
LANDSCAPE DESIGN AND CONSTRUCTION
During the excavation phase, a collection trench was dug at the base of the driveway to facili-
tate the rainwater harvesting process.
The underground collection basin at the foot of the
driveway was lined with a geo-membrane liner and
filled with large aggregate to allow water to gather and
thus serve as a cistern. The cistern was connected
with drainage pipes to an adjoining concrete box that
was equipped with a pump for yard irrigation. The
aggregate subbase of the cistern was then compacted
to allow for standard PICP system installation over it,
which includes graduated layers of smaller aggregate
to filter out pollutants and aid in water infiltration.
Combining a PICP system with rainwater harvesting
is eco-friendly, aesthetically pleasing, and utilitarian,
all in one system. (Product: Belgard Subterra Stone
permeable pavers.)
A combined permeable paver rainwater harvesting system is a multi-
faceted best management practice that accomplishes the ecological
goals of reducing stormwater runoff, improving local water quality, and
recycling rainwater for reuse.
