GRANITE FALLS — A proposed rock quarry expansion in Granite Falls will be influenced by an upcoming wetland review process.

The quarry, operated by Martin Marietta Materials headquartered in Raleigh N.C., is slated for an expansion toward the west side of its property. Preliminary evaluations showed the need to consider a wetland that was not designated in an earlier permit review conducted in 1992.

Jolene Johnson of the Yellow Medicine County planning and zoning office briefed county commissioners on the status of the wetland at this week’s board meeting. She expects the project to require a much more extensive permitting process than a typical zoning decision.

“We’ve been working back and forth between the quarry owners and the DNR,” Johnson said. “We know at this point that it will require an EAW (Environmental Assessment Worksheet).”

She said the EAW will be used to determine if there’s a need for an Environmental Impact Study. An EIS would involve detailed assessments of the wetland and surrounding natural resources. It could potentially delay the expansion plans.

She added that it’s unusual in 2020 to have a new wetland evaluation when the boundary of a property hasn’t changed.

Minnesota’s Wetland Conservation Act, created in the early 1990s, is intended to guarantee no net loss of wetland acres statewide. Most agricultural parts of the state lost up to 90 percent of their original wetlands after drainage projects in the early 20th century.

If a wetland needs to be drained or filled, property owners are expected to replace it with another wetland of equal or greater value.

Guidelines allow for wetland banking, in which restored or created wetlands can be banked as a credit for later drainage. Banking generally must take place in a location comparable to the area being drained.

Johnson said the wetland at the quarry site has been impacted by man-made activities in the past, which makes it a challenge to determine the most appropriate preservation requirements.

“It’s already been altered,” she said. “That’s part of what has to be considered. There will be information and public comments as part of the EAW, and that will help to determine whether or not there’s a need for an EIS.”

Martin Marietta Materials has business roots that go back to 1939 when Superior Aggregates was founded, according to the company website.

The company became the second largest aggregate producer nationally in 1995 after a merger. It was listed on the S&P 500 stock index in 2014.

Its aggregate, cement, concrete, and asphalt production spans 27 states, part of Canada and the Bahamas. Past acquisitions include Merdian Aggregates, which operated the Granite Falls quarry.

“We’ll weigh in on the need for an EIS as part of the zoning process,” Johnson said. “It will also be reviewed by the Minnesota DNR and the Army Corps of Engineers.”