INVESTIGATING LEAD OCCURRENCE IN MATERIALS FROM THE SOUTHSIDE CHATTANOOGA LEAD SUPERFUND SITE IN CHATTANOOGA, TN

Chattanooga has a rich history of steel production. In the late 1800s into the 1900s foundry byproducts from industrial processes were given to residents of southside Chattanooga as yard fill material. This area is home to parks, schools, neighborhoods and other residential and non-residential communities. In 2011, it was discovered that these foundry byproducts have high lead (Pb) concentrations. The EPA identified that the safety threshold for Pb in yard soils is 360 ppm. Pb concentrations in yards across Chattanooga greatly exceed that limit, resulting in the southside of Chattanooga becoming a Superfund site. These high concentrations have affected people in this community over the past decade through illnesses related to Pb exposure. Since 2021, Mineralogy students at the University of Tennessee at Chattanooga have investigated how Pb is occurring in yard materials using microscopy. The materials studied have Pb concentrations at 630 ppm and 948 ppm. This current research continues to investigate how Pb occurs in these materials microscopically. Specifically, this research hypothesizes that Pb occurs with other materials related to the steel making process. Yard materials from five sites across southside Chattanooga were collected and one modern baghouse dust sample was provided by TDEC (Tennessee Department of Environment and Conservation). Samples were first sieved down to 0.23 mm, tested with Lumetallix Pb detection kit, and particles that appeared to test positive for Pb were epoxied and examined under a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). In backscatter mode, Pb and other heavier elements appear whiter. We found 14 grains that contain Pb, with grains ranging in size from approximately 10-100µm in diameter. Of the 14, 10 were from the baghouse dust materials and 4 were from the yard materials. Some particles containing Pb, when analyzed with the EDS also have other notable metals such as Fe, Al, Cu, Sn, Zi, and Mn. These other elements are common additives in the steel making process. These initial results indicate the Pb-containing materials are from the foundry process. However, since a limited number of Pb-containing particles were from the yard samples, more analyses are needed to fully assess the occurrence of Pb in the soils.