Cleaning up a Pollution Puzzle in Ann Arbor
Host: Rebecca Williams
Show date: 07/31/2012
by Mark Brush
The city of Ann Arbor recently spent more than one million dollars rebuilding an old mill race along the Huron River. The Argo Cascades is a series of little waterfalls and pools where kayakers and people floating in inner tubes come to cool off.
But downstream from the Cascades on the other side of the river, there’s a problem.
There's been pollution lurking underground for some time from an old industrial plant, and two years ago regulators found that some of the pollution was making its way into the Huron River.
The days before natural gas
Kevin Lund is a senior geologist with the Michigan Department of Environmental Quality's Remediation Division. He told me to really understand what’s getting into the Huron River, you have to understand some history.
So he took me to a small parking lot about a quarter mile away from the river. It's directly across the street from the Amtrak station on Depot St.
He showed me an old brick and mortar foundation that was installed, he thinks, around the 1870s or 1880s. This bit of old foundation is one of the only things left of an old manufactured gas plant.
Back in the day, they manufactured gas here. Lund said the gas was originally used for street lights.
"There would be lamplighters, and then the extra gas was used for the people who could afford it to cook with and to light with," said Lund.
They made the gas by heating up chunks of coal, and trapping the gas that came off.
Manufactured gas plants were built all over. Any city or big hospital or company that needed gas often had one of these plants nearby.
Wherever they made gas from coal, they had a lot of leftover material. By-products such as coke, coal tar, and ammonia could be sold. But even so, there was still a lot of waste.
Burying the leftovers
Leftover coal tar, chemicals, and some metals, whatever they couldn’t sell, they often dumped.
“You got to remember they were no waste disposal facilities back in the day, and they didn’t move this stuff too far off their properties," said Lund. "So if there was a low depression in the property where they were doing the coal gasification, the waste products tended to find themselves over there.”
The old foundation Lund showed me was from the original gas plant in Ann Arbor.
It burned down, so they built a bigger one right next to the Huron River. As the town grew, so did the demand for coal gas.
Coal was brought in by the train load.
But in 1939, natural gas came to Ann Arbor, and that pretty much ended things for manufactured gas plants. Gas no longer had to be made. They could just pull it out of the ground.
The buildings were torn down, and they moved on.
The past bubbles to the surface
But old bricks aren’t the only things you’ll find around these sites. To get a look at what else was left behind, Lund takes me down to the bank of the Huron River next to the Broadway Bridge. Since there's been a drought, we can walk part way out into the river bed.
He scraped the gravel under the shallow water with his boot, and up popped a pool of black, gooey liquid.
Lund and another colleague from MDEQ discovered this stuff in the river bed two years ago.
“We were just collecting samples along the way and were finding exactly this all the way through here. And one of the locations that we dug, a hole in the bank, it filled with oil,” said Lund.
MichCon is the company responsible for the site. They took over the gas works in Ann Arbor in 1938 when the company consolidated several gas companies across the state. After natural gas came to the city a year later, the manufactured gas plant pretty much stopped operations. The buildings were torn down in the 1950s, and the site was used as a service center up until 2009.
Shayne Wiesemann is an environmental engineer with DTE Energy, MichCon's parent company. He's also the project manager for the cleanup on the site in Ann Arbor. He said MichCon has been monitoring the site since the 1980s, when he said they became aware of the problems there.
"These are exceedingly complex projects," said Wiesemann. "There were industrial operations here for nearly 50 years. You really have to do your homework."
Cleaning up our forefathers' mess
So far, Wiesemann said they've spent around $3 million on monitoring and clean up efforts. They've cleaned up some hot spots up on the property. They excavated 1,700 yards of underground contamination in 1998, and 5,000 yards in 2006. They also ran a groundwater cleaning system on the site for 5 to 6 years.
When they learned about the pollution coming in contact with the Huron River from the MDEQ, they began to develop a plan to clean it up.
In the first week or two of August, the company plans to spend another three to four million dollars to start digging the pollution out of the river bed and its banks.
He said over a two to three month period, they’ll haul out around five to six hundred semi-truck loads of contaminated dirt (25,000 cubic yards). Wiesemann says they hope to finish this cleanup sometime in late October to early November.
"We’re going to excavate the material, we’re going to take it to a type two landfill, and then we’re going to restore all that material with clean backfill," said Wiesemann. "And then we’re going to put on a cap, and this cap is going to prevent any future contaminant migration to the sediment that we backfill into the surface water within the river."
A company spokesman said the entire cost of this project could be passed onto MichCon ratepayers. Up until this point, the company says it has been able to use payments from insurance claims to pay for monitoring and cleanup.
During the cleanup, big trees will have to be removed along the river bank (other trees will be replanted), and when they begin to dig into the polluted sediment, it can be like cracking a spoiled egg open.
There could be strong odors - smells of naphthalene (like mothballs) or creosote. MDEQ officials said air monitors will be operated during the remediation to make sure the air is safe to breathe. Wiesemann said their contractors will use covering foams on the contaminated soil and other work practices to keep the chemical smells to a minimum.
Once this project is done, the old coal tar will be out of the river, but there will still be some pollution on the site.
Wiesemann says they’ll wait to see how the community wants to use the land to determine further cleanup.
A pollution problem around all of Michigan
This cleanup is big for an old manufactured gas plant, but it's not as big as the pollution cleanup DTE is working on at its "Station B" site along the Detroit River.
"The Broadway site... we’re looking 25,000 yards of material, and we’re going to excavate that material over two to three months, and then on the far end of the spectrum, you’ve got the Station B site where we’ve excavated nearly 300,000 yards of material and we’ve been doing it since last year," said Wiesemann.
MDEQ's Kevin Lund said, in addition to the site in Ann Arbor, he's actively working on polluted sites in Adrian, Albion, and Jackson, and he knows of others in Bay City and Grand Rapids.
It’s estimated there are around 70 old manufactured gas plant sites in Michigan. The two big utility companies in the state, DTE Energy and Consumers Energy, are responsible for 40 of them (DTE - 17, Consumers Energy 23).
But for some of the rest of these old plants, with so much time passing since they’ve closed, finding the people responsible for cleaning them up can be difficult. And the tar, oils, and chemicals will be underground for future generations to find.blog comments powered by Disqus