MIDLAND, Mich. -- Michigan environmental regulators said Thursday that they reached a long-sought deal with Dow Chemical Co. to clean up to 1,400 residential properties in Midland, home of its corporate headquarters and a plant that polluted the area with dioxin for much of the past century.
The state Department of Environmental Quality said it agreed with the company on the outlines of a cleanup plan, marking a milestone in on-and-off negotiations that began in the mid-1990s. Dow will cover all of the costs and will fill in the plan details and submit them for review next month.
The total cost of the plan won't be clear until it's known how many of the 1,400 properties require cleaning and how much work needs to be done, Dow and DEQ officials said. The company said it would offer to buy about 50 homes and lots in two areas close to the plant.
"This proposed plan represents tremendous effort by the many partners gathered to address Midland's dioxin issue," DEQ Director Dan Wyant said. "The proposal is just the beginning of the work that lies ahead. I commend Dow officials for their commitment to the community and Michigan's environment, and we look forward to working with them on this effort."
Property owners will get to decide whether to accept Dow offers to clean or buy their properties, spokeswoman Mary Draves said.
"Our focus is to bring about closure for the residents of the Midland community," Draves said.
Dioxin is a family of byproducts from industrial processes, including chemical manufacturing. The U.S. Environmental Protection Agency has described one form as likely to cause cancer.
Dow has acknowledged polluting some Midland neighborhoods as well as the nearby Tittabawassee and Saginaw rivers, their floodplains and Lake Huron's Saginaw Bay with dioxin for the better part of the 20th century, from the late 1890s until the 1970s, first by dumping liquid waste and later by incinerating it and creating airborne emissions that settled in soil downwind of the plant. Installation of new equipment drastically reduced the air pollution, state regulators said.
The company contends the dioxin hasn't harmed people or wildlife. It has spent more than $40 million on studies, sediment sampling and other preliminary work, including the removal of tainted soil from highly toxic "hot spots." One had the highest dioxin levels ever recorded in the Great Lakes region.
Environmental activists have accused the company of dragging its feet in agreeing on a plan to fix the damage.
In addition to the Midland deal announced Thursday, the company signed an agreement with the U.S. Environmental Protection Agency last November to clean a three-mile stretch of the Tittabawassee River near the company's Midland facilities. A solution for the remaining polluted waterways remains to be worked out.
Dow's plan will include sampling soil in Midland neighborhoods near the plant to determine which properties have enough dioxin in the soil – more than 250 parts per trillion – to require cleanup.
Michigan's default cleanup threshold is a more stringent 90 ppt. But the law allows some variation when scientific studies determine that local soil conditions justify it, said Brad Wurfel, a Department of Environmental Quality spokesman.
In Midland, studies showed that the 250 ppt standard was sufficient to meet legally required risk levels for avoiding cancer or other serious illnesses after ingesting dioxin-laced dust or soil over roughly 50 years, said Jim Sygo, the agency's deputy director.
In yards that are cleaned, 12 inches of soil will be removed and replaced with clean dirt topped with grass. Any trees or shrubs that must be removed to get the job done will be replaced as well. Previous measurements have shown that contamination above the 250 ppt level is limited to the top 1 foot of soil, the agency said.
The tainted dirt will be used as fill at the Dow plant site or taken to the city dump.
Sampling is scheduled to begin in June, following a 45-day comment period on Dow's plan that will include a public hearing. It could take up to six years to remove the tainted soil and finish landscaping work in all the affected neighborhoods, state regulators said.
Parks and schools in the area also will undergo sampling.
Michelle Hurd Riddick, a member of a local environmental group called the Lone Tree Council that is critical of Dow, questioned the legitimacy of the 250 ppt cleanup standard.
"We haven't seen the science behind it," she said. "We're concerned about that number and whether it will adequately protect human health, especially vulnerable populations such as children, developing fetuses and women of child-bearing age."
Dow's buyout offer to the Midland households is commendable, Riddick said. "But there are people along the Tittabawassee River with much higher concentrations of dioxin on their property who have never been given the option to relocate."