MADISON HEIGHTS, Mich. – A days-long cleanup has been underway in Madison Heights after a green substance started seeping onto I-696.

The substance was discovered on the eastbound side of the roadway, near the Couzens Road exit, on Dec. 20.

Where is it coming from?

Officials said the substance is coming from the basement of the now-condemned Electro-Plating Services on 10 Mile Road, which was the site of a massive cleanup in 2016 due to improperly stored hazardous waste.

The business had been cited by state officials for lack of compliance for nearly two decades before it was finally permanently closed after the complaints received in 2016.

Inspectors previously found an estimated 5,000 containers of hazardous waste and materials that were improperly stored, unlabeled, open and corroded or in very poor condition at Electro-Plating Services.

Below are photos of what officials found inside the business at that time:

Full Screen 1 / 59 Sludge drying in basement -- hazardous waste used as berm material (WDIV)

The business owner was recently sentenced after he pleaded guilty to storing hazardous waste without a permit.

How did it get there?

Officials said the substance moved from the basement of the business into the ground, where it contaminated groundwater. From there, it made its way to a drain that goes to the freeway.

MORE: Cyanide, other contaminants found near condemned Madison Heights business

It was oozing from the embankment.

Officials say a substance leaking onto I-696 is from Electro-Plating Services, a condemned Madison Heights business. (WDIV)

What is it?

The substance was identified as hexavalent chromium.

The Department of Environment, Great Lakes, and Energy said there is no threat to drinking water, but that there are high levels of multiple contaminants in the soil and groundwater near the now-condemned Electro-Plating Services.

Chromium, trichloroethylene (TCE) and cyanide were all discovered near the building.

Hexavalent chromium was found at at 0.14 milligrams per liter. The standard for drinking water is 0.10 milligrams per liter.

Read more: Substance made famous by Erin Brockovich is what was seeping onto I-696

The storm sewer eventually enters Lake St. Clair miles away, EGLE said. By the time the substance would get to the lake, “concentrations would be well below detectable levels although still a significant concern for incremental accumulation in the ecosystem,” EGLE said.

Hexavalent chromium is often produced during industrial processes. The chemical is known to cause cancer and targets the respiratory system, kidneys, liver, skin and eyes, according to the Occupational Safety and Health Administration.

More: Officials say green contaminant on I-696 is likely headed to Lake St. Clair

According to the EGLE, the “release likely contributed contaminants to the storm sewer system before it was discovered.”

A green substance oozes onto I-696 in Madison Heights. (WDIV)

What is being done?

The far right lane of eastbound I-696 at Couzens Road has been closed since Dec. 20.

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“We have cleaned out the sewers and the clean out drains between the facility and 696,” said Jill Greenberg, with EGLE. “We’re also in the process of cleaning up the basement of the facility.”

Tricia Edwards, with the EPA, said the cleanup is going to take time because there is a lot of clay in the area, and the substance is traveling onto the clay.

“The green liquid has significantly impacted the embankment where it came out, so we will be working with partners to see what sort of remediation will be required to clean that up,” Greenberg said.

As of Sunday afternoon, the affected catch basins have been cleaned and are being monitored.

A basement sump is being used collect and remove water from the basement into a portable tank, Greenberg said. She said it reduces the water migrating off site.

It is a temporary system that will remain under oversight from the EPA and EGLE until a long term solution is in place.

Cleanup efforts underway include:

Daily vacuuming of nearby catch basins.

Maintenance and inspection of sump pumps collecting contaminated water from both inside the facility and on the highway embankment.

Daily monitoring of air in the building using hand-held monitors.

Preparing for the impact of rain and freezing weather.

Crews have been cleaning up a substance that seeped onto I-696 in Madison Heights. (WDIV)

Legislators release statement

On Monday, Sen. Jeremy Moss (D-Southfield) and Rep. Jim Ellison (D-Royal Oak) issued the following joint statement:

“The news this weekend of a hazardous waste oozing on I-696 in Madison Heights is alarming. We’ve been communicating with those who are working to contain and clean up the site and are grateful for their swift response in monitoring this issue. Preventable situations such as this are why we must act with urgency to enforce stronger policies to hold polluters accountable and protect our residents. As our constituents join with their loved ones this week during the holiday season, we will continue to work with local, state and federal officials on cleanup efforts and will ensure residents are informed of any development of this ongoing situation."

Sen. Paul Wojno (D-Warren) and members of the Macomb legislative delegation released this statement:

“The news that hexavalent chromium, a known carcinogen, was seeping onto I-696 on Friday is yet another wakeup call that we must take environmental threats seriously. Whether it’s chromium-6, PFAS or lead, we are facing a serious public health crisis in this country because these chemicals can leach into soil and contaminate our water supply. There is no room for complacency in situations like this. Our Macomb legislative delegation is working to ensure clean-up efforts are conducted properly, that Lake St. Clair is protected and those responsible are held accountable, and that the public is kept informed as additional information is provided to us."

Macomb County Public Works Commissioner Candice S. Miller also released a statement:

“Michigan EGLE and EPA were quickly on the job and engaged in this clean up on what was essentially a holiday weekend. This issue points out the need to monitor and have a means to capture the storm water off our major freeways – which amounts to millions of gallons of water per year directly entering into Lake St. Clair and the Great Lake system,” Miller said. “This cleanup will continue through the holiday week and we appreciate this dedication. While we applaud the actions taken initially to clean up the business site where this hexavalent chromium was illegally stored, we are concerned by initial reports that the groundwater around this business was not tested or remediated, allowing this leakage on to I-696 to occur. It has been reported that $1.5 million was spent on this clean up, so to hear that the groundwater wasn’t at least tested, that raises concerns. We cannot continue to operate the way that we have in the past. The Great Lakes are a world treasure and we must work together to serve as their guardians. A single drop of this chromium 6 contamination that might enter the lake is one drop too much."