MORRISVILLE - In 1995 the Environmental Protection Agency began cleaning up contamination at the old 52-acre Koppers Co. Inc. site near what is now McCrimmon Parkway.

Now they are back for the third time, as required by law, to perform tests at the site to make sure chemicals such as pentachlorophenol and isopropyl ether are not impacting public health.

Workers started interviewing residents in the impacted area in Shiloh, on Feb. 16 and are expected to complete the five-year study by September, according to public documents.

The federal government declared the former Koppers wood treatment plant a “Superfund site” in 1989. As a Superfund site, the plant was eligible for the EPA’s toxic-waste cleanup program.

Koppers’ use of a hazardous chemical called pentachlorophenol to treat its wood contaminated the soil and water on the property. The chemical had also seeped into the groundwater.

For months the company had to send residents bottled water for drinking, and under orders from the EPA, had to extend town water lines in 1989. The company that bought Koppers, Beazer East of Pittsburgh, hauled away 775 tons of contaminated soil.

The last report, which came out in 2007, showed remediation efforts such as removing the PCP-laden soil off-site , installing wetlands and monitoring wells have worked, according to EPA documents.

Deed restrictions were also recommended to prohibit residential use at the site.

The EPA is inviting the community to participate in the 2012 study. To comment contact EPA Community Involvement Coordinator Tonya Whitsett at whitsett.tonya@epa.gov; call 404-562-8633 or toll-free at 877-718-3752. Comments can also be sent to U.S. EPA Region 4, 61 Forsyth St, S.W. 11th floor, Atlanta, GA 30303-8960.