Brennan wraps up Grasse River environmental remediation

J.F. Brennan Company crews have concluded environmental remediation efforts on the Grasse River in Massena, NY, – after 3.5 years.

This project had a challenging scope involving dredging, material processing, water treatment, mussel relocation, capping, and habitat restoration.

In the first step in the Grasse Rive project, a small crew of Brennan operators and office staff mobilized to the site in New York, to lay the groundwork for the project.

The primary goal of the cap pilot test was to install settlement monitoring equipment on the riverbed, followed by placing the components of a multilayered armor cap that would allow the client’s engineers to assess how in-place cap material would settle on the river bottom.

Once dredged areas were approved, two backfill plants followed the dredging operation, placing clean material back into the dredged areas to meet pre-dredge elevations.

A separate group of pushboats moved loaded barges of backfill material from the Route 131 Staging Area to the 2 backfill plants. Brennan also mobilized its custom long-reach amphibious excavator to the site to assist in dredging and backfilling nearshore areas and flood plains that could not be accessed with barge-based excavators.

The scope of capping operations in 2021 required placing a 2-layered cap across 195 AC, starting at the terminus of the armored cap placed in 2020, stretching to the mouth of the river.

Operations began working around the clock 24 HR per day, 6 days per week, placing a CIL like that placed in 2020. Once the CIL was verified complete, the second layer of non-amended sand termed a “habitat layer” was placed.

Throughout the final summer of operation, crews conducted several mechanical placement operations: backfilling certain areas dredged in Snug Harbor, placement of high organic content topsoil in flood plain areas, and covering over 3.5 AC of the river with a modified armor layer cap.

Photo: Brennan