The top priority on any Superfund remediation project is to make the site safe for human, plant and animal life. This requires removing, containing or limiting the effects of the site’s toxic substances. Increasingly, Superfund remediation is done with an eye toward green remediation that considers all environmental effects of remediation and includes options to minimize the environmental footprint of the cleanup.
When multidisciplinary teams of chemical, civil and environmental engineers collaborate, they can identify and act on opportunities to implement sustainable solutions, and even protect specific species. Remediation of the Tulsa Fuel & Manufacturing (TFM) Superfund site — transforming a barren landscape into a bee paradise — provides one particularly good example.
A Barren Moonscape
From 1914-25, Tulsa Fuel & Manufacturing operated a zinc smelter and lead roaster north of Tulsa in Collinsville, Oklahoma. Smelting activities resulted in large quantities of retorts, slag, building debris, ash, bricks and other waste materials being discarded on the site. Vegetation was sparse and portions of the site looked like a moonscape.
In 1999, the site was listed on the Superfund National Priorities List due to elevated concentrations of arsenic, cadmium, lead and zinc in site soils. This contamination from waste materials was causing unacceptable exposures to human health and the environment. Our team supported the Oklahoma Department of Environmental Quality (DEQ) cleanup of the TFM Superfund site by performing the remedial investigation, feasibility study, remedial design and remedial action oversight.
The remedial design included removal of waste materials and shallow contaminated soils to an on-site consolidation cell, thereby cutting off the unacceptable exposures. The smelter furnaces were confined to a 10-acre corner of the site, and the consolidation cell was positioned over this area of deepest waste accumulation. This placement reduced the volume of waste materials requiring excavation and transport to the cell, providing greener remediation by reducing fuel consumption and off-site backfill needed to complete the job. It also reduced construction costs and provided opportunities for redevelopment in other areas of the site.
An estimated 186,000 cubic yards of contaminated materials were excavated from the 60-acre site and placed within the consolidation cell. By the completion of remediation, the site was stripped of most of its topsoil.
Instead of importing topsoil at significant cost, we worked with the DEQ and the Northeast District-Oklahoma Cooperative Extension Service to develop a site restoration strategy. Using a BOMAG soil stabilizer, poultry house chicken litter was thoroughly ground and mixed into the surface clay to create a favorable growing environment. The team selected a seeding mixture that included smooth brome grass, red clover and fescue as the best option for site restoration based on the season, site conditions and a desire to minimize long-term maintenance. Within months, the site was completely revegetated.
Clover was particularly successful, covering more than 40 acres of the site. This created an opportunity for the family trust that owned the site. They worked with two local honey companies to populate the site with colonies of honeybees. In light of recent declines in honeybee populations, this partnership provided essential support for a threatened pollinator of food crops.
Although creating a honeybee home wasn’t the original goal of the TFM project, effective remediation planning and multidisciplinary collaboration created a valuable opportunity for species protection.