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Thomas Cahill drove into Chapel Hill July 24 with his head in the clouds. Rain
clouds that is.
It was a Monday morning and, the night before, there had been yet another gully
washer of a storm that had led to the subject Cahill had come to Carolina to
talk about: surface water, and what has to be done to manage it.
He surveyed mud-covered parking lots, checked out floodwater in Eastgate
Shopping Center and nodded his head. Beneath Eastgate's parking lot was a
culvert through which developers had tried to squeeze a section of a natural
stream. During the night of heavy rain, it had squeezed out with nowhere to go
but the parking lot above.
"I just loved it. I was probably the only happy face around," Cahill said two
days later as he stood before a group of faculty and staff at a meeting of
campus teams working on Carolina's master plan.
What Cahill had witnessed could be used as evidence to make his case for why
designs for stormwater management must be incorporated into the campus master
plan.
As part of its master plan work, Ayers Saint Gross hired the firms of
Andropogon Associates and Cahill Associates, both from the Philadelphia area,
to collaborate on developing an environmental master plan. Ayers Saint Gross is
the main consultant leading efforts to develop a new master plan.
The environmental master plan is being guided by an advisory committee of
Carolina experts, including Phil Berke, associate professor of city and
regional planning, and others familiar with N.C. laws and practices regarding
stormwater.
Andropogon is a landscape architecture firm known for ecological master
planning and sustainable design, including the restoration and management of
natural habitats.
Cahill Associates specializes in water resources engineering and is a leader in
innovative stormwater management.
The most obvious way to prevent the problems he'd seen at Eastgate is to limit
development within watershed areas, Cahill said.
Another way to limit runoff is to build parking lots made out of porous
concrete or asphalt, which allows rainwater to seep through the surface. The
surfaces would be underlined with a bed of stones with the capacity to store
excess water for days when the soil below it is saturated.
The water management plan being developed is for the central campus and the
Mason Farm tract -- including Finley Golf Course -- the North Carolina
Botanical Garden and the Friday Center area. The recommendations will be
integrated into the campus master plan before it is presented for approval to
the University Board of Trustees this fall.
Jonathan Howes, the co-chair of the campus advisory committee overseeing the
process, said the master plan calls for the redevelopment of south campus to
include more residence halls and academic functions, but it was initially drawn
without much thought given to the area's steep slopes and streams.
What the consultants found was that streams carried stormwater from substantial
watersheds subject to protection under tough environmental laws.
What that will mean is that buildings that had been envisioned along some of
these slopes must go elsewhere. The good news is that none of the buildings had
yet been linked with any particular department or use, Howes said.
The needed adjustments will have no effect on the four residence halls planned
for the intersection of Manning Drive and Skipper Bowles Drive.
"At the moment, I don't think there will be a net reduction of square footage,"
Howes said. "We're just going to have to be more attentive to the management of
stormwater and the preservation of these historic streams."
Thanks to tough new environmental rules, it is no longer a question of
aesthetics over practicality.
"Complying with new state and federal regulations is not an option, it's the
law," Howes said. "The manner in which compliance is achieved is the challenge
for us, and the opportunity. That's the good part about it. There are lots of
ways to do this."
For instance, remnants of the old forests that existed at the time the
University was built lie along portions of the stream slopes. The master plan
now calls for a commons area near the spring where some of the streams
originate.
This kind of preservation will enhance the network of pedestrian footpaths that
the master plan has called for all along. "It's certainly possible that more
areas will now be along a forested stream bank rather than an area stripped of
most of its natural beauty," Howes said.
Cahill said that land use planning and water resources management used to be
done independently of each other. Now, each must be done in concert to keep in
harmony -- growth balanced with conservation, buildings made to fit within
nature rather than take its place.
The overwhelming challenge is the excess stormwater runoff created by
development. It is intuitively obvious that when you bulldoze the land and
cover it with asphalt you have created an impenetrable wall between the rain
and the earth that prevents the rain from seeping slowly through the soil,
through cracks in the bedrock and into underground water systems that flow into
and "recharge" surface streams and lakes.
The N. C. Piedmont gets an average of 45 inches of rain a year, Cahill said.
Half of it will evaporate. In natural conditions, about one-eighth will run
off. The rest seeps into the ground at a rate of 1,100 gallons per acre per
day, provided that acre is still in a natural state.
The traditional development tool to dispose of runoff has been to run it
downhill through drainage systems, Cahill said. But that doesn't work. The
water carries surface pollutants ranging from car oil to yard fertilizer into
streams, lakes or manmade retention ponds.
And when too much rain falls, the water spills over into streets and yards the
same way water will spill out of a cup when kept under a faucet too long.
The parking deck serving Kenan-Flagler Business School, just as the parking lot
at Eastgate, sits atop a stream. Cahill said he had gone to the business
school, stood above a drain in the parking deck and looked down. He could see
the water rushing past, hear it gurgling as if gasping for air.
"You can put a stream in pipe and pave over it and put cars on top, but the
stream still lives," Cahill said.
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