Earlier this week, the U.S. Environmental Protection Agency added seven hazardous waste sites that pose risks to people’s health and the environment to the National Priorities List of Superfund sites. Among them is the Keddy Mill in South Windham.

According to a press release issued Thursday, Superfund is the federal program that investigates and cleans up the most complex, uncontrolled or abandoned hazardous waste sites in the country to protect people’s health and the environment. Keddy Mill has documented contamination of PCB in and around the former mill on the Presumpscot River. The designation allows federal money to be used in cleanup.

“Cleaning up contaminated land is critical to the protection of human health and the environment,” said Mathy Stanislaus, assistant administrator for EPA’s Office of Solid Waste and Emergency Response. “Superfund cleanups also play an important role in advancing the economic well-being of communities by turning formerly idle properties into productive community assets that can broaden tax bases, create jobs, enhance property values and support improved overall well-being.”

According to the release, the Superfund process entails first working to identify companies or people responsible for the contamination at a site, and requires them to conduct or pay for the cleanup. For the newly listed sites without viable potentially responsible parties, EPA will investigate the full extent of the contamination before starting significant cleanup at the site. Therefore, it may be several years before significant EPA clean up funding is required for these sites.

Six other sites were also added to the priorities list:

• MacMillan Ring Free Oil (former oil refinery) in Norphlet, Ark.;

• PCE Southeast Contamination (ground water plume) in York, Neb.;

• PCE/TCE Northeast Contamination (ground water plume) in York, Neb.;

• Unimatic Manufacturing Corporation (former chemical manufacturer) in Fairfield, N.J.;

• Wolff-Alport Chemical Company (former metal extraction facility) in Ridgewood, N.Y.; and

• Walker Machine Products, Inc. (former machine screw products manufacturer) in Collierville, Tenn.