USA: NSP Submits Ashland Wet Dredging Plan

Officials from NSP-Wisconsin, an Xcel Energy company, have submitted a proposed wet dredging pilot study work plan to the Environmental Protection Agency and Wisconsin Department of Natural Resources.

The work plan outlines industry-leading environmental dredging practices to remove impacted nearshore sediments at the Ashland Lakefront Site.

The sediments at the Ashland Lakefront Site show signs of contamination created or exacerbated by industrial and municipal uses and activities over many decades including lumber and rail operations, wood treatment facilities, municipal sewer/culvert/road development, a manufactured gas plant, industrial construction and a city dump.

“We appreciate the willingness of the EPA and WDNR to provide the opportunity for the parties to evaluate the ability of a wet dredge to safely and effectively remove the near-shore sediments at the site,” said David Donovan, project manager, NSP-Wisconsin. “We look forward to working together with the agencies on finalizing a wet dredge pilot program.”

In 2010, the EPA proposed a “dry dredge” approach to the clean-up of nearshore sediments which would likely require installing dozens of sheet pile walls and dewatering portions of Chequamegon Bay, before the sediments are excavated. Several industry experts have raised concerns about whether a dry dredge can be performed safely and without causing further harm to the environment.

By comparison, a wet dredge approach would allow removal of the impacted sediments without dewatering the area. During the work, modern and well-tested environmental wet dredging techniques would be used to first remove the lumber and slab wood debris, and then remove the impacted sediments. During the work, the dredge area would be contained by specially engineered environmental liners to prevent the spread of any contaminants from the area.

If the draft work plan is approved by the EPA, and an agreement is entered to perform the cleanup, the company said it could perform the pilot wet dredge as early as the summer of 2014. The pilot wet dredge is expected to take several weeks and will be coordinated with on-land cleanup activities scheduled for the site.

[mappress]

Press Release, November 7, 2013