LOWELL, MASS. –TRC Companies, Inc. has been awarded a patent by the U.S. Patent and Trademark Office for its cap design that prevents releases of coal tar, petroleum and other non-aqueous phase liquids (NAPL) from contaminated sediment at former manufactured gas plant (MGP) sites. While conventional sediment caps only delay eventual contaminant releases, TRC’s cap design stops NAPL migration.
From the late 1800s to the mid-1900s, manufactured gas plants (MGP) across the U.S. supplied homes and industry with fuel for heating, cooking, and lighting. The process to create the fuel at the industrial plants resulted in the release of residues including tar, sludge, oils and other wastes. Although many of the by-products were recycled, excess residues remain at thousands of MGP sites.
“MGP contamination is a significant issue nationwide and we have found a more effective way to manage it,” said Chris Vincze, President and Chief Executive Officer of TRC. “Our solution helps reduce client costs, protects the public health, and preserves the environment. We’re enormously proud of our staff for this innovative achievement.”
Gas that bubbles up from the degrading organic matter not only causes the migration of contaminants, but also leads to the failure of conventional sediment caps. TRC’s newly patented cap design stops NAPL migration and safely vents the gas to the atmosphere.
This patent is the first in a series of TRC applications covering cap designs for managing gas and contaminant releases at sediment sites. Two full-scale applications of this design have already been constructed for TRC utility clients. The cap is currently being used at a site in Ann Arbor, Michigan along the Huron River, and at a site in Bangor, Maine along the Penobscot River.