BENNINGTON, Vt. — Officials say construction has started on an extension of a municipal waterline in Bennington and the village of North Bennington to properties with private wells contaminated with the chemical PFOA, a suspected carcinogen.

The chemical was used at a now-closed plant in North Bennington owned by Saint-Gobain Performance Plastics.

The company has agreed to a pay $20 million for a public waterline extension to about 200 homes affected by contaminated private water supplies.

The Vermont Agency of Natural Resources said Thursday that the Bennington waterline extension will be 10 miles long and serve about 155 properties in the northwest section of town. The North Bennington village extension will be 4 miles long and serve 55 properties. The projects are expected to be completed a year from now.