State of Montana Newsroom
DEQ Responds to Abandoned Mine Flooding in Red Lodge
HELENA, MONT.—The Montana Department of Environmental Quality (DEQ) and the City of Red Lodge are responding to the flooding of portions of the Sunset Mine, an abandoned mine located just east of the Red Lodge Airport, affecting nearby landowners and city infrastructure. Testing showed the floodwater’s pH was neutral, indicating spring water that does not pose a threat to human health.
In early-July, DEQ was alerted that water at an estimated rate of 100 gallons per minute was entering into the basement of a property located at 221 Grant St. in central Red Lodge. A city public works investigation indicated the gravity drain that previously carried spring water from within the workings of the mine to the city’s stormwater system has failed. Dewatering pumps and gravity flow are currently helping drain the basement and garage of the home into a city sewer drain. In addition to the flooding of the Grant Street property, responding personnel are concerned the water pressure continues to build behind the mine bulkhead adjacent to the property, which could result in failure and presents a safety concern.
DEQ, its contractor Olympus Technical Services, and Red Lodge Public Works are prioritizing decreasing the head pressure to prevent further failure and structure damage. The plan to address rising groundwater levels is to excavate into the mine workings to install a temporary drain that will relieve pressure by dewatering the mine. This work has already begun.
The DEQ Abandoned Mine Lands Program has the ability to complete the work and is proud to support local governments in emergent issues such as this. DEQ will continue to collaborate with local leaders to find long-term solutions to the problem once immediate concerns are addressed.
Adjacent to the flooding property to the north is a concrete bulkhead labeled, “Sunset Mine June 23 1907.” The Sunset Mine was initially developed around 1901 and later acquired by the Northwestern Improvement Company in 1907. Mining was conducted steadily until a downturn in the late 1920s. The company stopped mining completely in 1932. Historic documents note that water was a constant problem in the west side mines, located immediately adjacent to the present-day property experiencing flooding.