COMMERCE — The water here is toxic.

This was discovered in 1979. George Mayer, a rancher who lives just outside this northeastern Oklahoma town of about 2,500, noticed that his horses’ hooves, tails and bellies were becoming stained a sickly orange.

In his pasture, water filled with heavy metals welled from the ground, bursting from century-old mining bore holes that had finally filled to the top.

Thirty years later, OU researchers are cleaning up the contaminated water on Mayer’s ranch with an organic water treatment system that, after almost a year of use, they are calling a success.

Tar Creek

An area roughly 40 square miles that includes portions of Commerce and the towns Pitcher, Cardin, North Miami and Quapaw is known as the Tar Creek Superfund Site.

The federal government in 1980 passed the Comprehensive Environmental Response, Compensation and Liability Act, creating a trust fund for the Environmental Protection Agency to clean up sites deemed environmentally hazardous.

Tar Creek was put on the National Priorities List in 1983.

From the early 1900s through the 1970s, the area was mined for lead and zinc ore, according to the Oklahoma Plan for Tar Creek.

The process left a waste product, called chat, that looks like limestone gravel. It was piled into grey mountains, some up to 200 feet tall, that now tower above the small towns and blow lead-filled dust in the wind.

The process also left miles of underground tunnels, bore holes and mine shafts, which, over time, filled with water and surfaced. The water mixed with the metals, becoming acidic.

The water — which has high concentrations of lead, zinc, iron, cadmium and arsenic — has killed fish and plants and has contaminated the soil around it.

OU Research

When William Strosnider, an OU environmental engineering doctoral student, first walked on Mayer’s ranch about four years ago, he sank into the orange sludge that covered the ground and was, in some places, waist-deep.

Today, the sludge is gone. Flowers and grass now grow on the land that was without any vegetation a year ago.

And on the site runs the result of years of research and planning: the nine-acre passive water treatment system that OU researchers designed with the engineering firm CH2M Hill.

The system builds on natural processes that were cleaning the water on a much smaller level.

“Nature was kind of doing the work, but we’ve set the stage for nature to do it a little more efficiently by confining it,” Strosnider said on the ranch Wednesday.

Classroom on the Superfund site

The project has been funded by the EPA and the U.S. Geological Survey through the Oklahoma Plan for Tar Creek, a multi-agency plan designed to address issues in the area.

Multi-year research and work on the site was funded by two different research grants with total agency funding of over $6.1 million over five years, said Robert W. Nairn, an OU engineering professor who has helped lead the research.

The contracts run out next year, he said, and he and others are writing proposals for more.

OU has given approximately $156,000 in tuition reimbursements to graduate students involved in the research, he said.

About a dozen OU engineering graduate students currently monitor the system with Nairn, who has brought many students to the site for research over the last decade.

At least 30 theses and dissertations have been written about the site, Nairn said.

“We look at this as a living laboratory,” he said. “If you’re going to be doing environmental work, you have to get out in the environment.”

Small groups of students make the three-and-a-half-hour drive to the site at least once a month for monitoring and maintenance.

When they do not have enough research grant money for hotel rooms, they camp in tents in a state park nearby.

Strosnider has been coming to the site for four years.

“To me, it’s especially cool because I was here when it was just a sludgy wetland,” he said. “It’s completely different now.”

Cleaning the water

Nairn and Strosnider led a group of local residents, city government officials and reporters through the area last week.

The system, which cost $1.2 million to design and build, was completed in November 2008. It consists of a series of 10 ponds, each of which has a specific function in the cleaning process.

Water flows between the ponds naturally via gravity.

Once the orange water comes out of the ground, it enters the first pond, which is U-shaped.

The air around it smells musty and metallic, like the inside of a charcoal grill long after the fire has burned out.

The smell is rust, Nairn said.

Water flows into this pond at a rate of about 150 gallons per minute, Nairn said. The 4-foot-deep pond is designed to remove the iron from the water by letting it solidify into rust so it can settle to the bottom of the pond and separate from the water.

Nairn said the pond is built to last 30 years before the solid iron has to be recovered. Students are trying to determine if the materials will be able to be used, he said.

“Even if we can’t recover that material, we’ll have a positive environmental impact,” Nairn said.

After water is filtered in that pond, the flow is split, and water drains into two identical shallow ponds, which act as wetland filters. The rest of the iron settles in these ponds.

The water flows from these ponds into two more identical ponds that are filled with organic compost. These ponds are called vertical-flow bioreactors.

Water flows into the pond through valves and has to pass through the compost and a layer of limestone at the bottom, both of which continue to filter the water.

In these conditions, microbes that digest the metal particles grow naturally.

“They grow and prosper and are happy, and they help us clean the water,” Nairn said with a smile.

By the time the water reaches the bottom, it is free of zinc, cadmium and lead.

In the next two ponds, oxygen is pumped back into the water since it is removed in the underground process in the previous ponds.

Pumps, much like those in fish tanks, bubble in these two ponds. The pumps are powered by wind power from a 20-foot windmill between the ponds and by solar-charged batteries.

Water flows from these ponds into two beds of limestone targeted at zinc removal.

The zinc, Nairn said, is the most difficult to remove.

As water moves horizontally through the limestone, the zinc hardens, and the water is filtered.

From here, the parallel water structures are joined, and all of the water flows into one final pond, where most particles that remain settle.

The water from this pond is discharged through a pipe and released back into the ecosystem. It drains into an unnamed tributary and, eventually, into the Tar Creek stream.

It takes about three weeks for water to flow through the entire system.

After it does, the once-orange water is clear.

Back into the ecosystem

The system is designed to remove about 105,000 pounds of iron, 6,000 pounds of zinc, 500 pounds of nickel and 200 pounds of aluminum every year.

It also removes 40 pounds of arsenic, 33 pounds of lead and 8 pounds of cadmium.

The tributary into which the water flows has seen the return of plants and animals.

The system cleans about 20 percent of the contaminated water in the Tar Creek watershed, Nairn said.

Nairn and other OU researchers update the EPA four times a year with project results.

“We’ve been keeping them well-informed,” he said.

He said he hopes the project, which he called a demonstration project, will be seen as proof that the water can be cleaned naturally and that cleaning can be done on a larger scale.

“We are committed to monitoring and trying to understand the system over a lifetime,” he said.

Nairn said that the EPA deemed Tar Creek “irretrievably damaged.” This project, he said, will “hopefully influence them to change their tune.”