Sewage Blending Stirs Up Debate

  • Many environmentalists fear the practice of sewage blending would become more routine if a new EPA policy is enacted. (Photo by M. Vasquez)

Officials at the Environmental Protection Agency are considering a new policy for sewage treatment plants. Many environmentalists say if the policy is adopted, it will lead to increased water pollution and greater risk to public health. The Great Lakes Radio Consortium’s Mark Brush reports on the debate over sewage blending:

Transcript

Officials at the Environmental Protection Agency are considering a new policy for sewage treatment plants. Many environmentalists say if the policy is adopted, it will lead to increased water pollution and greater risk to public health. The Great Lakes Radio Consortium’s Mark Brush reports on the debate over sewage blending:


(sound of water in sewer)


Some sanitary sewers are tied in with storm sewers. So when there’s a big rainstorm, or when there’s a fast snowmelt, all that water can inundate some sewage treatment plants. To tackle this problem, some treatment plants have adopted a practice known as “blending.” The excess sewage is re-routed around the slower parts of the treatment plant. The dirty water is then mixed with the water that’s been cleaned. It’s sometimes given a shot of chlorine, and then released into creeks, rivers, and lakes.


Kurt Heise oversees the operation of a sewage treatment plant on the Detroit River. He says the practice of blending is necessary in order to keep the plant from being overwhelmed.


“When you have a wet weather event, an extreme wet weather event, if we were to allow all of that combined water in through the normal process the treatment process would be ruined.”


Sewage blending has been around for a long time. To plant operators, it’s a necessary step in handling large amounts of dirty water. But to some people, blending is not seen as a good option. They want the practice to stop.


Instead, they say, cities should invest in their systems to make sure they can fully treat all the water that comes to the plant. Kurt Heise says, if his plant were required to do this, it wouldn’t make sense economically.


“It would almost result in doubling the size of our plant and spending just untold amounts of dollars for an event only happens a few times a year.”


Sewage treatment plant operators say you have to weigh the costs and the benefits before spending hundreds of millions of dollars on expanding the treatment plants. The decision of whether or not to allow blending has been left up to state and local regulators. But recently, the U.S. Environmental Protection Agency has weighed in on the subject. And ever since they suggested new guidelines for allowing blending, environmentalists have been critical of their plan. Mike Shriberg is the Great Lakes advocate for the Public Interest Research Group. It’s an environmental consumer activist organization.


Shriberg says the draft blending policy, the way it’s written now, is too broad. And will allow the practice of blending to become routine.


“Our fear is that when you’ve got a treatment plant that uses blending, they’re never going to upgrade to full treatment sewage. And so if a treatment plant is allowed to blend they’re not going to go up to full treatment capacity they have no incentive to do that anymore. It’s sort of the cheap way out.”


Sewage treatment operators say blending is better than seeing the raw sewage overflow into waterways. And they say it’s better than spending large sums of money to fix a problem that only occurs a few times a year. But critics say the EPA doesn’t have a good handle on how often blending is used, and what kind of health risks are associated with the practice.


Some initial studies have been done on blended sewage and how it might affect public health. Joan Rose is a water microbiologist at Michigan State University. She’s written a report on the health risks associated with blended sewage.


“So what I found was that if people were actually swimming in the water and there was a discharge of a blended sewage upstream, that their risk of getting sick, actually getting sick with a virus or a parasite was about a hundred times greater – when there was a blended discharge as opposed to if the water was fully treated.”


Rose says some of these viruses, such as Hepatitis-A, are highly contagious. At this point, there are no good estimates on how many people get sick from blended sewage each year. It’s never been studied, so the impact of blending on public health is unclear. Ben Grumbles is the Assistant Administrator for water at the EPA. He says the EPA is considering the billions of dollars at stake in expanding the nation’s sewer treatment plants versus the risk to public health.


“What we’re trying to do is to clarify what’s legal and what isn’t legal and to recognize the economic realities that sewage teatment plants face across the country in terms of their infrastructure needs, but foremost and above all what leaves the facility has to meet Clean Water Act permit limits.”


But the Clean Water Act permit limits don’t measure all the viruses, bacteria, and parasites found in blended sewage. And so some environmentalists and scientists say meeting the limits doesn’t necessarily mean protecting public health. Grumbles says officials are still reviewing the tens of thousands of comments they received after releasing the draft blending policy.


He says he doesn’t know what the final rule will look like, or if they’ll issue a rule at all. One thing is likely, if the policy is finalized the way it’s written now, it’s expected that environmental groups will take the EPA to court.


For the Great Lakes Radio Consortium, I’m Mark Brush.

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Major Dock Corrosion Stumps Officials

  • The Duluth Seaway Port Authority's bulk cargo dock is typical of many in the port. Officials are troubled by corrosion appearing on the docks in the harbor - the steel is corroding much faster than normal. (Photo by Bob Kelleher)

Corrosion is eating away at the steel walls that hold one of the Great Lakes’ busiest harbors together. The corrosion is unlike anything known to be happening in any other Great Lakes port. But other port officials are being encouraged to take a closer look at their own underwater steel. The Great Lakes Radio Consortium’s Bob Kelleher reports:

Transcript

Corrosion is eating away at the steel walls that hold
one of the Great Lakes’ busy harbors together. The
corrosion is unlike anything known to be happening in
any other Great Lakes port. But other port officials
are being encouraged to take a closer look at their own
underwater steel. The Great Lakes Radio Consortium’s
Bob Kelleher reports:


Some kind of corrosion is eating away at the Duluth
Seaway port’s docks. The docks are those long
earth-filled metal rectangles where ships from around
the world tie up to load and unload. Those docks are
lined with sheets of steel, and the steel is rusting
away. Jim Sharrow is the Duluth
Seaway Port Authorities Facilities Manager.


“It’s corroding quickly – much faster than people expect
in fresh water. And our main concern is that we’ll lose
the integrity and the strength of the dock long before
expected, and have to do steel replacement at $1,500 or
more per lineal foot, much earlier than ever would have
been expected.”


Corrosion should be a slow process in Duluth’s cold
fresh water. But, Sharrow says, there’s evidence it’s
been happening remarkably quickly for about thirty years.


“What we seem to see here is corrosion that started in
the mid 1970s. We have steel that’s 100 years olds
that’s about as similarly corroded to steel that is 25
to 30 years old.”


It’s a big problem. There’s about thirteen miles of
steel walls lining docks in the harbor that serves
Duluth, Minnesota and Superior, Wisconsin. There’s half
again as many feet of wooden docks, held together with
steel pins. There’s corrosion on the legs of highway
bridges and the giant
steel ore docks that ship millions of tons of taconite
– a type of iron shipped to steel mills in Gary,
Indiana and Cleveland, Ohio.


“We characterize this as a 100-million dollar problem in
the harbor. It’s a huge problem, and what is so odd
about this is that we only see it happening in the
navigational area of the Duluth-Superior Harbor.”


The harbor links the St Louis River with Lake Superior.
Go a few miles up the river and there’s little corrosion
. So it doesn’t seem like the problem’s there. But, back
in the harbor, at the current rate of corrosion, Sharrow
says, the steel will fail quickly.


“I figure that in about 10 years at the current rate,
we will have to start replacing steel.”


“Particularly marginal operators could decide rather
than repair their docks it would be better for them to
go out of business, and we’re hoping that that isn’t
the case here.”


While the cause is a mystery, there’s no shortage of
theories. It could have something to do with stray
electrical voltage; water acidity; or the kinds of
steel manufactured in recent years. Chad Scott
discovered the corrosion in the late 1990’s. He’s an
engineer and a diver. Scott suspects
a micro-biological connection. He says there might be
something growing in small round pits that form on the
steel.


“We cleaned up the water. That’s the main thing –
that’s one of the main changes that’s happened since
the 70s, is we’ve cleaned up our water. We’ve cleaned
up our harbor, which is a good thing. But, when we
cleaned things up we also induced more dissolved oxygen
and more sunlight can penetrate the water, which tends
to usually promote more growth – more marine
microbiology growth.”


A team of experts met in Duluth in September to share
ideas. They came from the U.S. Navy, The Army Corp of
Engineers, and Ohio State University. And they agreed
there’s something odd going on – possibly related to
microbes or water chemistry. They also recommend that
other Great Lakes ports take a closer look at their
underwater steel. Scott says they at least helped
narrow the focus.


“We have a large laundry list right now. We want to
narrow that down and try to decide what is the real
cause of this corrosion. And these experts, hopefully,
will be able to get us going on the right direction,
so we can start doing testing that will identify the
problem.”


With the experts recommendations in hand, port
officials are now planning a formal study. If they
do figure out the cause, then they’ve got to figure
out how to prevent it. They’re in a race with
something, and right now they don’t even know with
what.


For the Great Lakes Radio Consortium, I’m Bob Kelleher.

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