2001 Capping Pilot Study

Overview

A pilot study of capping techniques was conducted in a section of the lower Grasse River between July and October 2001 to better understand how different capping materials could be installed on the river bottom using various placement techniques. Capping is being evaluated as a possible cleanup alternative that may be considered along with other alternatives for contaminated sediment in the lower Grasse River.

Capping is a technique where clean materials are placed on top of contaminated sediments to isolate the contaminants from the environment. The primary contaminant of concern in the Grasse River sediment is polychlorinated biphenyls (PCBs). PCBs are a group of more than 200 manmade chemical compounds, and were widely used in industry for their insulating and flame retardant properties. These chemicals were primarily used in hydraulic systems and transformers at the Massena Operations. The manufacture and sale of PCBs were banned in the United States in 1979.

The capping pilot study was conducted by Arconic (formerly Alcoa) with oversight from the US Environmental Protection Agency (EPA), US Army Corp of Engineers and the St. Regis Mohawk Tribe.