CEE professor plays key role in campus storm water
management
 t’s easy to blame recent flooding in Dane
County on record-setting spring rains. But people are as much at fault
as the weather, according to Professor
Ken Potter. “We’ve disrupted the hydrologic cycle,”
he says, “and we have only tinkered with fixing it.”
The good news, Potter says, is that a new storm water
management policy at UW-Madison is a big step toward a real fix. Approved
last fall by university officials, the policy calls for redirecting
as much storm runoff as possible on the 930-acre campus into the ground
rather than into Lake Mendota. Not overnight, but eventually. You could
call it an endorsement of the trickle-down effect.
Potter helped organize a group of faculty and staff
members and graduate students that spent much of last year scrutinizing
storm-water management on campus. Now they are plotting ways to improve
it. Their work is supported by a grant from the Wisconsin Department
of Natural Resources to the university’s Gaylord Nelson Institute
for Environmental Studies.
 |
|
|
Water runoff
from UW-Madison's new power plant on the west side of campus will
be stored or pumped to recreation fields to prevent it from flowing
into nearby Lake Mendota.
(24K
JPG) |
|
| |
Currently, much of the rainfall and snowmelt on developed
parts of the campus that does not evaporate or soak into the soil either
flows into storm sewers, which empty into Lake Mendota, or runs directly
into the lake. That simple strategy made sense in the past, but today
it can backfire.
Under natural conditions, most of the precipitation
that fell on what is now Dane County accumulated in natural depressions
and seeped into the ground. As farmers converted the land to agriculture,
they drained the depressions, compacted the soil and triggered erosion,
producing more storm runoff.
More recently, urban and suburban growth has transformed
increasing areas of the county into landscapes of buildings, streets,
driveways and parking lots. These impervious surfaces seal off the ground
beneath them, leaving storm water fewer places to go and creating flooding
problems downstream. Detention ponds, built to catch runoff and release
it slowly, help somewhat, but they do little to reduce total runoff
amounts.
Potter says all this is why heavy spring and summer
rains now increasingly cause flooding around the Yahara Lakes, including
some parts of campus, often yielding substantial property damage. The
solution, he says, is to keep more storm water close to where it falls
until it can evaporate or soak into the ground.
Even in dense urban areas, there are many ways to
do this. “Rain gardens”—clusters of water-tolerant
plants in bowl-like depressions—are one increasingly popular tool.
Permeable pavements, such as porous concrete blocks, are another.
“Permeable pavements have been shown to work
in places like Sweden, where the climate is similar to ours and they
have to contend with snow and ice,” says Potter. “Entire
roads of permeable pavements have been built in the Netherlands and
Oregon. There’s no reason why they can’t work here.”
Potter’s group has scouted campus for locations
where storm water could be better managed with these and other remedies.
Their search has turned up some surprises.
“The students found that most green spaces
around here are as hard as rock,” says Potter. “On the big
lawn in front of the Kohl Center, if you dig down six inches, it’s
solid clay. That’s because when the building site was excavated,
the clay was spread in front. Then it was just covered with turf. The
students observed that when it rains, the water runs off the lawn instead
of sinking in. So you’ve got a very large green space acting as
if it were a roof. We could correct that relatively easily by replacing
the compacted ground with soil that absorbs more water.”
Potter believes the gradual redevelopment of the
eastern end of the campus called for in the university’s long-range
plans will provide many opportunities to improve the way storm water
is handled in that area. The rapidly growing western portion of the
campus presents different challenges because the land is lower and wetter.
Nevertheless, Potter sees opportunities there, as well. And staff from
the university’s Facilities Planning & Management division
have been working closely with Potter’s students to help integrate
some of their ideas on campus.
Instead of flowing into storm sewers, for example,
the runoff from the roof of the West Campus Cogeneration Facility, a
power plant under construction on Walnut Street, will be piped into
the soil beneath nearby athletic fields or stored in surface depressions.
Campus facilities staff are also looking at potential
rain gardens, infiltration trenches and “green roof” technologies
for new campus buildings to clean up the storm water, slow it down and
infiltrate some of the water before it gets to Lake Mendota.
Already, UW-Madison has replaced a deteriorating
parking lot at Angler’s Cove, a popular fishing spot near Eagle
Heights, with a smaller parking area and natural landscaping designed
to keep storm water from scouring away the fragile lakeshore. The university
also has applied for financial assistance to rebuild a large parking
lot near the shore of Lake Mendota so that virtually all of the rainfall
on the lot seeps into the ground.
Potter says continued urban and suburban growth in
Dane County will intensify the need for enlightened storm water management.
“Only five to six percent of the Lake Mendota
watershed - the land area that drains into the lake - is impervious
now,” he notes. “We’ve only begun to develop it. Most
of the watershed north of the lake is still farmland. As that becomes
more developed, the problem will only get worse.”
|
|
| |
