SOUTH BEND, Ind. (AP) — South Bend is turning to sensors
and computers instead of pipes and tanks in hopes of keeping untreated
wastewater from flowing into the St. Joseph River during heavy rain
storms.
The city best known as the home of the University of Notre
Dame is making a name for itself for how it is tackling combined sewer
overflows, which occur when systems designed to collect rainwater runoff
and domestic sewage in the same pipe overflow, sending untreated sewage
and industrial waste into natural waterways.
"South Bend has
always been a leader in this. They’re one of the first ones to look at
this and say, ‘This could really be a cost-effective way to maximize the
existing public infrastructure,’" said Paul Calamita, general counsel
for Wet Weather Partnership, a national coalition of communities working
to reduce sewer overflows.
The federal Environmental Protection
Agency estimates that more than 770 U.S. communities with a total
population of 40 million depend on combined sewer systems that mix
sewage with storm water at times of heavy rainfall or snowmelt. Most of
those cities are in the Northeast, the Great Lakes region or the Pacific
Northwest.
The Indiana Department of Environmental Management
says more than 100 communities across the state use combined sewer
overflow systems. The drainage systems were built so that when heavy
rains or snowmelt filled pipes, the overflow would gush into rivers and
other waterways. The EPA says the overflows can create serious public
health and water quality concerns, contaminating drinking water, closing
beaches and causing other environmental and public health problems.
Fixing
the problem is going to cost each city millions. South Bend, which has
40 square miles of sewers dating from the 1950s, entered into a 20-year,
$509.5 million consent decree with the EPA in December to address its
overflow problem. The decree is awaiting approval by a judge.
Gary Gilot, South Bend’s public works director, hopes the city’s high-tech system
will save the city about $120 million.
Working
with a company called EmNet LLC in 2008, South Bend began installing
116 manhole covers equipped with sensors to measure how full a pipe is.
The covers also have a radio to transmit the information every five
minutes to a computer system.
That allowed the city to see in real
time what was happening underground. The early detection has helped cut
the number of dry weather overflows, which occur when debris gets into
the system and clogs a line, from an average of 27 a year to one over
the last two years, Gilot said.
It’s an improvement over the old
system, in which the two city workers would lift up manhole covers to
try to spot trouble. Often, problems weren’t discovered until a resident
reported a backup in a basement.
The system also allows the city
to see when debris keeps an overflow flap open, allowing water from the
St. Joseph River to flow into the sewer system. Gilot said the city’s
water treatment plant was treating an average of an extra 10 million
gallons a day from water flowing in from the river. The city now treats
more than 30 million gallons a day.
The city also has installed
valves that can divert water throughout the sewer system. Since storms
don’t usually hit all neighborhoods with the same intensity, water can
be held back in areas where rain is less intense and flow freely in
areas of heavier downpours.
Luis Montestruque, EmNet’s chief executive officer, compares it to a program that
allows cities to control traffic congestion.
"This
system not only tracks where the traffic is, but it also controls where
it is that the congestion is," he said. "The idea was to now use all of
this information to allow the sewer system to reconfigure itself, to
adapt itself to the change in precipitation in terms of time and
intensity throughout the city."
Gilot believes the system will
allow South Bend to go from the 70 to 80 overflows a year it had before
it started using the technology to a maximum of four.
Calamita
said the system like the one South Bend is using probably won’t work in
rapidly growing cities, but it could be an answer for older cities that
have dwindling populations and excess sewer capacity.
"It’s an
unknown if this is a 1 percent, 5 percent, 10 percent or 30 percent
solution," Calamita said. "If it’s a 1 or 5 percent solution, it’s
probably not worthwhile. But to the extent it’s a 10 to 30 percent
solution, then people are going to be very interested."
Copyright 2012 The Associated Press.