Superfund Site Profile
The Southwest Jefferson County Mining Site includes all of Jefferson County, Missouri, excluding the Herculaneum Site. Jefferson County is located on the northern portion of an area known as the Old Lead Belt where mining began in the early 1700s. Mine waste has contaminated soil, sediment, surface water and groundwater at the site with heavy metals, primarily lead. Mine waste has also been transported by the Big River and manually relocated to other areas throughout Jefferson County. In residential properties, this material has been used as topsoil, fill material and aggregate for roads. The site is separated into eight Operable Units (OUs). OUs 1-3 includes the residential properties. OU 4 includes the Big River and flood plain, OU5 includes Groundwater, OU 6 is the Valles Mines area, OU 7 is the Rail Lines and OU 8 is the mine waste areas. EPA work at the OUs is on a priority basis based on the potential for human health and environmental risks.