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Storm Drain System Metro Detroit Michigan

August 17, 2014 8:00 AM
Officials study ways to lessen burden on storm systems
By Chris Gautz at Crains Detroit Business magazine

Last week’s historic and severe rainstorm that caused massive flooding
in metro Detroit is causing local officials to think more about how
they can prepare for future bouts with Mother Nature.

One problem is that the storm water systems in place are up to
state standards, but just aren’t designed to handle the
amount of water that fell — as much as 6 inches in
three hours in some parts of metro Detroit.

“The investment required and infrastructure required to
withstand what happened on Monday would have been cost
prohibitive to build,” said Craig Covey,
the community liaison for Oakland County
Water Resources Commissioner Jim Nash.

So what can be done?

Finding ways to lessen the burden on those systems,
which in many cases rely on aging infrastructure,
is something more communities are looking at,
said Karen Kabbes, president of the environmental
and water resources institute at the
Washington, D.C.-based American Society of Civil Engineers.

“When you have an extreme rainfall event,
new pipes may not be the answer,” she said.
“It’s stepping back and looking at the whole system.”

One of the easiest and cost effective ways to do that,
Kabbes said, is using green infrastructure.
Some of the more common examples include rain gardens,
green roofs and installing pervious concrete in
parking lots that allow water runoff to be absorbed
into the ground rather than flow into storm drains.
That water can then be recycled by
property owners for sprinkler systems or other uses.

Madison Heights City Manager Ben Myers and
Ferndale City Manager April Lynch said their
communities require new construction projects
to retain their own stormwater,
rather than send it into the city system.

The current system is a legacy of a time when
less ground was covered by parking lots and other development.

“All the rainwater that hits them needs to go
somewhere, and it can end up people’s basements,”
Covey said.

He said a combination of increased investment
and encouraging policies that result in less
stormwater flowing into sewer systems will
help because the likelihood is that we
will see more, not fewer of these kind of storms.

“These unusual rain events are not unusual anymore.
This is our little piece of the climate change,” he said.

Luke Forrest, program manager at the Michigan Municipal League,
said the use of green systems varies, but is most
common in Grand Rapids and Ann Arbor right now.

“This type of runoff highlights the standards aren’t
widespread enough,” he said. “For the most part,
the green approach is still seen as experimental
in a lot of places.”

Forrest said these changes can help lighten the load
on the local water and sewer infrastructure,
but does not lessen the need for replacing
aging pipes and drains.

“We have a lot of ancient infrastructure
doing the job,” Forrest said.

A 2001 report from the Southeast Michigan Council
of Governments found that between $14 billion
and $26 billion was needed by 2030 to maintain
and improve Southeast Michigan’s sewer infrastructure.
Much of that cost comes from maintaining and fixing
the existing system as well as overflow and capacity issues.

At the time of the report, it found that about
60 percent to 70 percent of the region’s
sewerage system was more than 30 years old.

Now, most of that infrastructure is more than
40 years old because not much has been fixed,
said Amy Mangus, leader of plan implementation
at SEMCOG. County and local officials agreed
that while work is done each year to replace
or fix older pipes, there is still plenty
that they can just not afford to do.

“We’ve been keeping up,” Lynch said of Ferndale’s
storm water system. “But the cities are old so
all of us along the corridor have an older system.”

The concern many local officials have is that the
next time such a large storm hits, the flooding
and damage done to homes and businesses could
be much worse if pipes crack or the systems
in place break down because of their age.

The stormwater systems in place in the region are
typically meant to handle a 10-year storm event,
meaning they can handle a storm that has a 10 percent
chance of occurring each year. Last week’s storm was
considered a 300-year storm event,
meaning it has a 0.333 percent chance of occurring annually.

“You don’t design sewer systems for 6 inches of rain”
in such a short amount of time, Mangus said.

How the system works

In a typical rainstorm, water travels into storm drains
in the streets, through a pipe and toward a water treatment plant
where it is treated. In the case of larger storms,
there are 22 retention treatment basins in the
region that are used to house excess stormwater and
sewage that the treatment plant cannot process
because it is at capacity.

With typical large storms, the retention basins hold water
until the treatment plant has capacity again.
But with the kind of severe storms the region
saw last week, the basins treat the water
on-site and then release it into nearby rivers and streams.

The largest retention basin in metro Detroit
is the George W. Kuhn basin near I-75 and 12 Mile Road
in Madison Heights. Completed in 2006, it was designed
to state standards for a 10-year storm event
and can hold 124 million gallons.

“It performed as it was designed, but it was
overwhelmed,” Covey said. “There is no man-made
structure than can hold up to whatever
Mother Nature decides to throw at you.”

At the height of Monday’s rain event, the basin facility
was treating 6,700 cubic feet of stormwater per second
with a chemical called sodium hypochlorite,
similar to what is used in swimming pools.

In a typical large storm, all of the water is treated
before it is released into the Red Run Drain,
an open stream that eventually flows into the
Clinton River. But there was so much water Monday
that not all of it was completely treated,
though all of it was at least partially treated, Covey said.

Warren Mayor Jim Fouts said the Red Run crested
so much it was coming up to people’s front porches.

“This was unlike any weather disaster
I’ve experienced,” Fouts said.
“I’ve never had a storm where
our main streets are like rivers.”

He said the system in place was
not to blame. “We just had a monumental,
catastrophic, Biblical-type of storm.”

But he does blame politics in part.

For several years, there has been haggling
between Warren and Macomb and Oakland counties
about the cost of connecting the city
to the Oakland-Macomb interceptor drainage district.
That turned into a lawsuit in
June 2013 that has not been resolved.

Fouts and Macomb Public Works Commissioner
Anthony Marrocco said they believe if Warren
were connected to the system,
residents would not have had so many flooded basements.

Covey declined to comment on the case
because of the litigation,
but noted many homes across
the region had flooded basements.

Once storm recovery efforts have
settled down, Fouts said he plans
to talk with his staff about
what can be done to prepare for future storms.

Meyers said Madison Heights has a neighborhood
road millage and whenever it uses those
funds to replace or fix local streets,
it also fixes the sewer and stormwater
systems in those areas while it has the roadway open.

Last week, there was not a
defect in the system, he said.

“(The stormwater) just completely
exceeded the design capacity of the system,”
Myers said.

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