A mining company that operates a sand and gravel mine on Lower Grey Cloud Island in Cottage Grove, Minnesota, wants to expand and shift operations into the Mississippi River – and mine the actual riverbed.

Holcim MWR Inc., formerly Aggregate Industries, is proposing to move its mining area to mine additional aggregate reserves on about 400 acres of privately owned land that it leases adjacent to the existing facility in the backwaters area of the Mississippi River on Lower Grey Cloud Island.

There are only about five years of life remaining in the existing permitted Nelson Sand & Gravel Mine Facility; the expansion could extend the life of the mine by another 20 to 25 years, according to a draft environmental review of the project.

But officials from St. Paul-based Friends of the Mississippi River, a river advocacy group, have raised concerns about Holcim’s plan and its potential impact on the river.

The proposed mining operation would be the first of its kind in the state. A spokeswoman for the Minnesota Department of Natural Resources, one of the key permitting agencies for the proposed project, said the agency had never “permitted a mining project of this scope or magnitude within a major river.”

Holcim plans to mine the river bottom to a depth of about 200 feet in sections of the proposed expansion site, according to a post on the Friends of the Mississippi River website. “Leftover material would be used to backfill the newly created mine pit, but only to about 100 feet. This would leave a deep mine pit in the river bottom. The surrounding area is mostly shallow — no deeper than 25 feet.”

Some of the most significant impacts could be to plants and animals at the site, including some endangered species, the post states. “Mussels have been identified as particularly at risk of harm,” the post states.

Concerns about possible recreational and scenic impacts also have been raised. “To reduce water flow into the mine pit, a low earthen berm would be constructed between some of the existing islands,” the Friends post states. “The berm would be approximately 1,500 feet long and 100 feet wide at the crest. This berm, in addition to the needed mining equipment, would be visible from the surrounding area, including Spring Lake Park Reserve. Impacts from the existing mine, such as noise, would continue for the next 20-25 years as the new area is mined.”

The state usually owns riverbeds, but the proposed expansion site is privately owned “because it didn’t actually used to be underwater,” the post states. “The construction of Lock and Dam 2 downstream in 1930 increased the water level and submerged this upland site.”

City, state and federal roles

The key permitting agencies on the project are the Minnesota Department of Natural Resources and the U.S. Army Corps of Engineers.

Cottage Grove officials are handling the environmental review of the project to assess the potential for environmental impacts. The scope, scale and amount of environmental impact of the project automatically put the environmental review at the level of a more-detailed environmental impact statement, said City Administrator Jen Levitt.

The draft EIS comment period, which is prescribed by state law, runs through Jan. 17.

Once completed, the EIS will provide detailed information about the extent of potentially significant environmental impacts of a proposed project, present alternatives to the proposed project and identify methods for reducing adverse environmental effects, Levitt said. The role of Cottage Grove, as the responsible governmental unit, “is to ensure the EIS is complete and has addressed all of the environmental concerns,” she said.

The city will not be addressing any local permitting issues until the Minnesota Department of Natural Resources and the Army Corps of Engineers have approved a permit, Levitt said.

Larson Quarry expansion

Holcim MWR Inc. also operates a rock quarry in neighboring Grey Cloud Island Township, and company officials are proposing to move that operation onto adjacent lands, a move that could extend the life of the mine by up to 25 years.

Holcim is proposing to expand the Larson Quarry onto an adjacent 148-acre property that the company owns just east of Washington County Road 75; the company has owned the land since 1972.

No change in quarry operations or production levels is proposed. There are only five to seven years of life remaining in the existing permitted quarry area; the expansion could extend the life of the mine by 20 to 25 years, according to an environmental review of the project.

©2024 MediaNews Group, Inc. Visit at twincities.com. Distributed by Tribune Content Agency, LLC.