Washington County Lead District-Potosi

Potosi, Mo.	

Site Description

The Washington County Lead District-Potosi site is part of a family of related Superfund sites located
in Washington County, Mo. From the 1700s until the mid-20th century, numerous mines were built
there to exploit the area's rich reserves of metals such as lead and barite, which are poisonous to
humans and animals. The act of transporting the metals to the surface and then processing them led
to widespread contamination of soil and groundwater. The Potosi site comprises about 47-square
miles and includes multiple towns (one of which is named "Potosi"). EPA added the site to the
National Priorities List in 2008, and the Record of Decision for Operable Unit 1, Residential
Properties was signed in September 2011. Many residential yards and drinking water wells are
contaminated, and large piles of metal-laced waste dirt exist throughout the site.

Current Site Status and Cleanup Actions to Date

	In 2008, EPA started a remedial investigation, which includes characterization of numerous
tailings ponds and streams, determination of the extent of groundwater contamination and the
completion of residential surface soil characterization.

	Assessment activities are ongoing and include sampling private properties for lead-
contaminated surface soil and drinking water. EPA estimates that 825 remaining properties
require assessment of soil and water.

	Through short- and long-term actions, EPA has replaced contaminated surface soil at 204
residences and provided bottled drinking water to 126 residences whose drinking water wells
were contaminated above federal drinking water standards.

	Although funding and completion of this project will result in environmental progress, it will
not eliminate all unacceptable human exposure pathways. Additional work will be needed to
do so.

Unfunded Action

Fiscal Year 2012 work that was not funded included excavation and disposal of lead-contaminated
residential surface soil from an estimated 870 properties.

Current Funding Status

To date, EPA has spent approximately $18.2 million on response construction work at the site.

For more information on this site, please read the Washington County Lead District-Potosi
	site information on the Region 1 Superfund web site.