Water Resources Research Act Program

Details for Project ID 2018SC108B

Monitoring Distribution and Toxicity of Coal Tar Chemicals in the Congaree River Using Passive Samplers

Institute: South Carolina
Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $30,061 Total Non-Federal Funds: $60,129

Principal Investigators: Peter Van Den Hurk

Abstract: A large area of the riverbed of the Congaree River in downtown Columbia, SC is contaminated with coal tar. This coal tar originates from a former nearby manufactured gas plant, and has generated environmental and public health concerns. Coal tar consists of a number of toxic compounds, among which are carcinogenic polynuclear aromatic hydrocarbons (PAHs). No information is available documenting negative effects of the coal tar on biota in the river, but locals who use river for recreation have complained about health effects after coming in contact with the contaminated sediments. South Carolina Electric & Gas, who has responsibility the plant and its legacy, and the SC Department of Health and Environmental Control are in the process of determining how to clean up the site. An initial assessment revealed that about 11 acres of riverbed are contaminated with coal tar, in concentrations that warrant cleanup. After the initial environmental assessment, SCE&G formulated several different alternatives for managing the site. The preferred option is to remove all contaminated sediment, but after a failed pilot project, and a technical review of the potential impact of altered river flow due to the construction of a required temporary cofferdam, this was deemed not feasible. The current alternative under consideration is to cap the site with geotextile and riprap. Despite intermittent analysis of sediment and water samples, SC DHEC has admitted that little is known about the potential effects of the coal tar contamination on biota in the river. An investigation into the effects on invertebrate communities did not show significant differences between locations downstream and upstream of the site. But invertebrates are known to be relatively insensitive to PAH pollution, which warrants further studies on the effects of the coal tar on fish populations in the river. We propose to apply passive samplers around the contaminated site to obtain time integrated data on the leaching of PAHs and their metabolites from the site. This will significantly increase the knowledge about how much toxicants are being released from the sediment, because the samplers are collecting these pollutants over a 4 week period. This time integrated collection of contaminants is a huge improvement over one-time grab samples. The passive samplers will be outfitted with different absorbing materials that collect non-polar and moderately polar chemicals, like the PAHs and their more water soluble metabolites. The samplers will be deployed upstream and downstream of the coal tar site, and the absorbing materials will be replaced on a monthly basis to obtain a seasonal picture of the toxicants leaching from the site. In addition, we propose to test the extracts from these samplers with a fish toxicity test. The concentrated extracts from the samplers can be used in a small volume fish embryo toxicity test, which will generate information on the potential effects on fish populations in the river. An additional benefit of this proposed project is that after the initial deployment, and analysis of the passive sampler extracts to establish an overview of the current situation, the same procedures can be used during mitigation activities on the site, and afterwards during recovery of the ecosystem. This will give a time line assessment of pre, during and post mitigation mobility and release of PAHs from the site. The results from this project will immediately benefit SC DHEC in their management of the cleanup of the coal tar site, and the developed protocols can be used during mitigation and post-mitigation assessments. Initial conversations with SC DHEC personnel have been encouraging for this project, and if the project is selected for funding, close collaboration with SC DHEC will be established. In addition, undergraduate and graduate students will be involved in the project, which will form a real-world case study for them on management of environmental problems, and the application of new scientific techniques that help evaluate mitigation projects.