NJDEP Cites Mercer County After Bridge Work Sends Sediment Into Stony Brook

MERCER COUNTY, NJ - The New Jersey Department of Environmental Protection sent a Notice of Violation to Mercer County after sediment from an emergency bridge repair project entered the Stony Brook near Hopewell Valley Golf Course.

County officials were notified on the evening of Oct. 9, of the issue at the construction site, where a contractor had been completing emergency repairs on County Bridge #230.10, which carries Pennington-Hopewell Road over the Stony Brook.

Staff received reports of sediment entering the waterway and learned that NJDEP had been contacted over the weekend regarding the discharge.

The Notice of Violation allows the county to take remedial action to remove sediment from the stream.

According to County executive Dan Benson, in June, Mercer County awarded an emergency contract to repair the bridge after extensive scouring created a serious risk of failure. As part of the work, the contractor built an earthen dam to access portions of the bridge foundation normally underwater.

When the contractor began removing the dam following completion of construction, silts and clays were released into the stream, causing grayish discoloration in the water.

“County engineering staff have assessed the site and determined that no sediment plume has extended beyond Hopewell Twp. The clay used in the earthen dam was natural, clean fill from a quarry — not cement or chemically treated material,” Benson said.

“The observed turbidity was due to the natural color of the clay used on-site, which poses no known chemical or environmental threat to wildlife or humans.”

Mercer County is working with the Mercer County Soil Conservation District to address the situation. Turbidity barriers have been installed to prevent further spread of discoloration, and sediment bags are being deployed to absorb excess silt.

The county has also received permission from NJDEP to use pumps for additional sediment removal.

County officials thanked The Watershed Institute and Hopewell Township for quickly alerting authorities to the issue, enabling a rapid response.

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