Harnessing Biosolids to reclaim mine lands: Case studies from Appalachia

Over several decades, Denali has worked with landowners and mine operators to reclaim thousands of acres of mine lands in Appalachia using organic residuals. The residuals have primarily been biosolids sourced from large municipalities. This work has been a tremendous success and shows the potential of using biosolids to improve water quality, establish vegetative cover, create and maintain wildlife habitat, and improve the economic value of mine lands in the Eastern United States, of which there are hundreds of thousands of acres. From the point of view of municipalities and recycling organizations, mine lands are exceptional outlets for large amounts of organic residuals due to state and federal regulators typically allowing application rates of biosolids in excess of typical agronomic rates. The reasons for this include: the need to introduce large amounts of organic matter to restore soil health where topsoil has been almost entirely removed; the need to correct soil and water pH; and the negligible negative impact of pollutants due to the relatively short window of application. Denali's two case studies on this subject are land reclamation at a surface coal mine in Western Pennsylvania and a copper mine in Southeast Tennessee. The Western Pennsylvania site is an example of how coal mine operators can partner with organic residual managers to revegetate areas alongside active mining. This partnership shows the promise of on-site lime stabilization of biosolids in accordance with the U.S. EPA's 503 rule. In Pennsylvania, Denali has utilized approximately 500,000 wet tons of biosolids to reclaim over 2,900 acres of mine land. With nearly three decades of experience in Pennsylvania, it is proven that lime stabilized biosolids neutralize acidic soil and provide an organic-rich foundation to reestablish an ecosystem that is more robust than traditional mine reclamation. This process has turned moonscapes into meadows and has revitalized wildlife habitats. Although this mine site is far from the East Coast cities that generate the biosolids, the economics of biosolid landfill disposal in the Eastern U.S. allow for the added costs of transportation. Additionally, the large amount of carbon stored in the restored soils of these mine sites more than cancels out the greenhouse gas emissions associated with transporting the biosolids from the cities to the mine sites. In Tennessee, the Copper Basin Mining District supported copper mining and smelting operations for more than 140 years. Mining companies used smelting to separate the copper from the ore, and they cut timber to fuel the smelters. The resulting sulfuric acid and deforestation devastated the environment. The basin became a barren man-made dessert of red clay that covered thousands of acres. In recent years, a new landowner in the mining district used conventional fertilizers in an attempt to revegetate the most severely impacted areas, but this method failed and was costly. As an alternative, the landowner began working with Denali to bring lime stabilized Class B biosolids to the site. The effects on vegetation and water quality have been profound. Applying lime stabilized biosolids was found to be an effective way to restore grasses and hardwoods. As water passed through areas revegetated with biosolids, surface waters that previously had a pH of 2.0 transitioned to a pH of 5.0, and both fish and waterfowl have returned to several ponds and creeks. Denali recently began working with the land owner to deploy lime stabilization equipment onsite to create a Class A material to support the reclamation plan, which is being administered under U.S. EPA's Superfund program. Comparing these two case studies shows that the use of lime-stabilized biosolids can be effective in diverse mine reclamation settings. The ecology, mining legacies, and economic drivers at the two sites are distinct. Yet, Denali's process has been successful at both. The cost effectiveness, the ecological success, and the abundance of biosolids that could be put to work suggest that more residuals management professionals should become aware of mine reclamation as an opportunity to reuse waste, sequester carbon, support natural resource and land conservation efforts and divert organics from landfills.