Planting poplar trees to remediate brownfields in Muskegon, MI

Brownfields dot city landscapes across the Great Lakes region. Often a health hazard to local communities, brownfields are also an eyesore that lowers property values and discourages new development. The process to cleanup, or remediate, the land can be costly and time consuming. Many communities are looking for creative, interim land management strategies that clean up the soil while also providing important ecosystem services, like stormwater management.

Since 2013, Delta Institute has been working with partners in Muskegon, Michigan to implement an interim strategy that uses phytoremediation to begin the clean-up process and return the land to productive use. With funding from the U.S. Forest Service, Delta planted 3,000 hybrid poplar trees on several brownfield sites in Muskegon. These trees are able to uptake and stabilize environmental pollutants in the soil, and as they mature rapidly, the wood can also be harvested for commercial use.

How does phytoremediation benefit brownfields?

Phytoremediation is the direct use of green plants and their associated microorganisms to stabilize or reduce contamination in soils, sludges, sediments, surface water, or ground water. Hybrid poplars are excellent for phytoremediation, because they grow rapidly and take up contaminants, like heavy metals, chlorinated solvents, and volatile organic compounds (VOCs). Heavy metals are toxic to aquatic life at certain concentrations and can bio-accumulate in the fatty tissue of fish, leading to fish consumption advisories, while chlorinated solvents and VOCs, like benzene, toluene, and trichloroethylene (TCE), can persist for years in the soil and ultimately percolate into a community’s drinking water.

In addition to soil benefits, the poplar tree farms can also provide important ecosystem services. The trees absorb significant amounts of water, reducing stormwater run-off, which the U.S. EPA has identified as the most important remaining uncontrolled source of water pollution. Stormwater carries sediment, oil, grease, toxics, pesticides, pathogens, and heavy metals into nearby storm drains, where it usually enters local streams and waterways.

Delta’s planting site in Muskegon was part of the sprawling Lakey Foundry, which was situated on 20 acres and operated from 1914 to 1972. Lakey produced iron engine castings for the automotive, agriculture, and appliance industries, and was renowned for polluting the air with acrid smoke and dust. The soil in and around the site of the foundry is contaminated, as well as the groundwater that flows under the site. The poplar tree planting area is approximately two acres on this site and will act to remove the environmental contaminants left behind by the foundry.

Phytoremediation also yields local economic benefits

Delta’s Todd Parker with Dave and Chris from Montague Tree Farm, contractors on this project.

The benefits of these poplar tree farms extend also to the local economy. Hybrid poplars are among the fastest growing trees in North America, producing between four and ten dry tons of wood per year and achieving a height of up to 60 feet in as little as six years. The forest products industry contributes $16.3 billion per year to Michigan’s economy in direct, indirect, and induced contributions, and it provides more than 77,000 jobs. Poplar trees are well-suited as a source of wood fiber for bioenergy, as well as lightweight wood for cabinets, doors, and paneling.

In researching the potential end uses of poplar, Delta identified 73 businesses in West Michigan that use poplar. The types of uses range from lumber, pallets, and fuelwood to crafts, mulch, and millwork. All of these businesses represent potential end users of the hybrid poplar trees.

In the long-term, phytoremediation at these sites will result in improved soil and water quality and new economic opportunities for the Muskegon community. This project supports Delta’s ecosystem stewardship objective and demonstrates how green infrastructure strategies can yield both environmental and economic benefits to communities and regions.