SOUTH WINDHAM – The Environmental Protection Agency has placed the Keddy Mill complex in South Windham on the National Priorities List, also known as the Superfund, pushing the contaminated site one step closer to a federal cleanup effort.

According to Kate Melanson, the community involvement coordinator for the agency’s New England regional office, the listing makes the Keddy Mill site formally eligible for a federally funded cleanup effort.

The listing was proposed on Dec. 11, when the agency’s New England office announced that it would formally seek to place the Keddy Mill complex on the National Priorities List. Despite the listing, Melanson said, the cleanup could be up to a decade away. The timeframe depends on a variety of factors, including the future of the agency’s budget, she said.

For now, Melanson said, the agency will conduct a search for the “potentially responsible parties,” or firms, that contaminated the Keddy Mill site. If such parties were found, the agency would initiate a legal action in order to force them to fund the site cleanup, she said. If not, the agency will likely clean up the site using available federal funds, she said.

“It kind of depends on who’s contributed to that contamination and who’s still around as a viable potentially responsible party,” Melanson said. “We do a big background search on who could be around that would be able to pay for the cleanup.”

Melanson said agency officials will conduct research in the area in order to determine who contaminated the site.

“We do talk to people that have worked at places like this before, or have lived in the area for a long time, people that might have a better history of the site than we would,” she said.

The former mill, located at the corner of Main and Depot streets in South Windham, served as a paper and steel mill during its 100-plus-year history. The large concrete building, which town officials say is starting to disintegrate rapidly, has sat unused since 1997.

The 6.9-acre site contains extensive contamination from PCB, or polychlorinated biphenyl, a toxic substance once used in mechanical parts that was banned by Congress in 1979. The federal Superfund program addresses properties where remediation of toxic soil or water can cost millions, and where previous owners cannot be expected to cover the entire cleanup cost.

Town Manager Tony Plante said that he could not say who had contaminated the site.

“They’re going to be chasing it down to try to figure out who was responsible for contaminating the site, and I’m not in a position where I can say,” he said. “The most recent owners as far as we know had nothing to do with bringing or introducing contaminants to that site. It was some owner somewhere in the chain of title, and that’s part of what the EPA is going to have to figure out.”

In October 2011, Portland-based real estate development firm Lumas Inc., obtained the property at no cost from the previous owner, a New York City investment firm that planned to build condominiums on the property before discovering toxic waste during construction. A Lumas official said the firm used to own the Keddy Mill from 2000-2004 but didn’t use the property during that time.

Asked in 2011 why the Portland-based firm would purchase a heavily contaminated site that state and federal environmental officials expect will take years and millions of dollars to rectify, the Lumas spokesman said the company was already in the chain of title and wanted to be directly involved in negotiations with the government.

If federal dollars are brought to bear, Lumas could benefit by regaining use of the property after cleanup is complete.

Plante said the reason the federal government needs to clean up the site is that the job has been financially prohibitive for private entities.

“I had a couple questions as to why don’t we just have a private developer go in and do something with it,” Plante said. “We’ve worked with a handful of private developers trying to redevelop the site and make it a contributor to the village again, but the presence of the contamination makes it financially infeasible. It just doesn’t work. The numbers don’t work.”

According to the Keddy Mill narrative posted on the National Priorities List website, PCB contamination is “widespread throughout the site and inside the abandoned mill building.” The narrative states that the two main sources of contamination are a pile of slag material north of the vacant mill and an area of contaminated soil that extends from the north of the building southwest to the Presumpscot River. Also, according to the narrative, samples show that stormwater run-off has released PCBs into the Presumpscot River, potentially contaminating nearby wetlands.

The agency also notes that the site has been vandalized and poses a health risk. Lumas erected a fence several years ago to prevent trespassing.

“Potential contact with PCBs in surface soil and within the mill poses a health threat,” the agency’s narrative reads.

The Maine Department of Environmental Protection has been studying the site intensively in recent years. The department determined that the scale of the cleanup exceeded the ability of the state-administered brownfields program to pay. Due to lack of funding, the state asked the U.S. Environmental Protection Agency to investigate the site for possible inclusion on its list of Superfund sites. The sprawling property achieved a score of between 50 and 54 on a scale of 100 based on preliminary soil samples by the federal agency. A score of at least 28 is needed to be considered for the Superfund list.

Tom Bartell, Windham’s economic development director, characterized the listing as a mixed blessing.

“You don’t want to be known as the town with the Superfund site, but it is a very important program on the national level,” Bartell said. “It’s a recognition of the difficulties at the site, and it puts it into a position of action being taken to clean up that site. At some point we hope to be able to redevelop that site into something that will be an asset to the South Windham village.”

“It’s a step forward,” Plante added.

South Windham’s Keddy Mill last week was added to the federal Superfund list, enabling it to qualify for federal cleanup money.