Friday, August 22, 2014

Guest article: Mine haul roads and their potential environmental impacts

By Esteban Chiriboga, GLIFWC (Great Lakes Indian Fish and Wildlife Commission) Mapping Specialist

Published in GLIFWC's Fall 2014 issue of MAZINA'IGAN. Reprinted here with permission. 

Eagle mine haul road under construction. No evidence of silt fencing or erosion control best management practices is visible. (Photo © and courtesy Esteban Chiriboga. Reprinted with permission.)

MADISON, Wis. -- Mine haul roads are integral parts of a mine operation. These roads can vary in size from single lane dirt roads located within the footprint of a mine to multi-lane paved highways used to transport materials to and from a mine site. Roads located within the mine footprint are usually included in the analysis of potential environmental impacts of a mine. However, roads that lead away from the project site to processing areas or regional shipping hubs are often overlooked, and the impacts that occur along these transportation routes may be discounted.

The Red Dog mine in Alaska is one of the more notable examples of a project that has impacted the environment along its haul road. This open pit zinc, lead and silver mine transports crushed rock from the open mine pits to a concentrating facility. From there, the concentrate is transported via a 50-mile haul road to a port facility. Sampling along the haul road conducted in the early 1990s showed elevated concentrations of metals on the road surface and on the road shoulder. This finding led to additional studies which indicated that metal deposition has occurred along the road, and concentrations decrease with distance from the road right-of-way. Elevated metal concentrations in several plant species are detectable up to 1600 meters (approximately 1 mile) from the road (ADEC, 2002).*

The source of the metals is concentrate dust that adheres to the truck tires as well as trace amounts of concentrate dust on the surface of the trucks (ADEC,2002).* It is important to note that the trucks have hydraulically sealed doors that completely enclose the concentrate inside. Even with this precaution, contamination has still occurred.

Here in the Lake Superior region, there are ongoing concerns about impacts along mine haul roads in Minnesota and Michigan ceded territories. The proposed PolyMet mine in Minnesota is very similar to Red Dog in its operations and design. Although in the case of PolyMet, the crushed ore would be transported by rail and not by truck, GLIFWC staff are concerned about the potential for environmental impacts along the rail line. PolyMet proposes to use open rail cars that have gaps along the side door hinges to transport ore from the pit to the processing facility. There is no question that ore dust will escape the cars through these openings. In response to GLIFWC comments, the lead agencies for the PolyMet Environmental Impact Statement (EIS) have required water quality monitoring along the rail corridor between the pits and the processing facility. GLIFWC staff will continue to advocate for the use of sealed rail cars to reduce the possibility of contamination along the rail line.

The construction of a mine haul road also impacts the environment. The Eagle mine in Michigan is currently rebuilding sections of a county road to accommodate large ore trucks.

The Eagle mine haul road has caused habitat fragmentation in this biologically rich area. (Photo © and courtesy Esteban Chiriboga. Reprinted with permission.)

The construction of this road through a remote area involves filling of wetlands and numerous stream crossings. This area, which is included in the Lake Superior Binational Program Important Habitat List as an area of high biodiversity, has suffered habitat fragmentation due to this construction. It is possible that the use of salt in the winter will lead to water quality impacts in the area’s small creeks, and unintended ore dust deposition along the route is likely. Additional impacts may result from pumping water out of local creeks to use in dust suppression activities during construction.

Tanker spraying water for dust control along the Eagle mine haul road construction site. (Photo © and courtesy Esteban Chiriboga. Reprinted with permission.)

To our knowledge, the effects of pumping on creek water levels and biota have not been characterized. In addition, dust suppression often involves mixing the water with chemicals, and the effects of these chemicals have not been identified.

GLIFWC staff have and will continue to advocate for inclusion of mine haul roads in the analysis of environmental impacts of proposed mine projects. In the case of the road construction at the Eagle mine, the environmental impacts of the road were not evaluated when the permits for the mine were considered. The Eagle mine’s haul road is permitted under general state permits that are issued for road construction. These general permits, while often adequate for normal roads, do not require the data and analysis needed for a road that will be used to transport mine concentrate and/or metallic ores. These materials are often reactive when exposed to air and water and, as exemplified by the Red Dog haul road, can create environmental impacts in very small quantities. The failure to evaluate infrastructure associated with mining activities appears to undermine the goal of clearly disclosing all impacts associated with mineral development projects. Mine haul roads should also be included in any analysis of the cumulative impacts of multiple mine projects on the ceded territories.

*Alaska Department of Environmental Conservation (ADEC), 2002, Fugitive Dust Background Document -- Draft Report.

GLIFWC's publication MAZINA'IGAN is available on line. Click here to read more of their recent articles on Great Lakes issues.

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