WASHINGTON COUNTY LEAD DISTRICT - POTOSI MISSOURI EPA ID# MON000705023 EPA Region 7 City: Potosi, Cadet, Mineral Point, Springtown, Happy Hollow, Shibboleth, Summit, Bates Creek Camp County: Washington Other Names: 12/22/2008 SITE DESCRIPTION The Potosi Site encompasses an area greater than 45 square miles in the eastern portion of Washington County, Missouri. It primarily includes residential areas within and around the communities of Potosi, Cadet, Mineral Point, Springtown, Happy Hollow, Shibboleth, Summit, and other smaller communities, and is a portion of the larger Washington County Lead Mining District. The Potosi Site is mostly residential, although a number of commercial businesses are present. Soil and/or groundwater contamination by arsenic, barium, cadmium, and lead at the Potosi Site is most likely the result of lead and barite mining, milling, and smelting. Continuous lead mining began in Washington County in 1721 at the surface and near-surface (ten feet or less below ground surface (bgs)) in an area north of Potosi. Galena, the main lead ore, was mined in both the red clay residuum, which generally ranged from a few feet to over 30 feet thick, and the underlying dolomite bedrock. Barite (barium sulfate), another local mineral, became valuable after the Civil War and barite mining began to boom in the area in 1926. Remnants of mining activities throughout the area include strip mines, mineshafts, mine dumps, tailing areas, tailings ponds, and associated dams. There are numerous large tailings impoundments, associated dams, and leachate ponds with elevated levels of lead in surface soil present at the site. Site Responsibility: NPL LISTING HISTORY The site is currently being addressed through federal action. Proposed Date: 09/19/2007 Final Date: 03/19/2008 Deleted Date: ------- THREATS AND CONTAMINANTS Extensive lead contamination in surface soil, at levels exceeding health-based screening levels, has been identified at 716 residential properties at the site. Occasional elevated levels of barite, arsenic, and cadmium have also been identified at the site. In addition to surface soil contamination, 138 private drinking water wells have been identified with lead levels exceeding the federal drinking water standard of 15 micrograms per liter. CLEANUP APPROACH Response Action Status Initial Actions: Removal Assessment activities are ongoing and consist of sampling private properties for lead-contaminated surface soil and drinking water wells. Through Time-Critical Removal Actions, contaminated surface soil has been replaced at 180 residences, and bottled drinking water has been provided to 126 residences whose drinking water wells were contaminated above federal drinking water standards. Site Studies: The initiation of a Remedial Investigation (RI) occurred in January 2008. The RI will include the characterization of numerous tailings ponds and streams, determine the extent of groundwater contamination, and complete the characterization of residential surface soil. Residential interior dust samples have been collected for developing the Human Health Risk Asssessment. ------- Site Facts: An Action Memorandum was signed on October 17, 2005, for Time Critical Removal actions to be taken to replace residential surface soil contaminated with high lead levels and to provide bottled drinking water to residents with lead-contaminated, private drinking water wells. ENVIRONMENTAL PROGRESS 1601 residential properties have been sampled for surface soil metals contamination. 764 private drinking water wells have been sampled for metals contamination. Lead-contaminated surface soil has been replaced at 180 residetial properties. Bottled water is being provided to 126 residences. COMMUNITY INVOLVEMENT EPA has facilitated several public meetings to inform citizens of site contamination and removal actions. EPA, with the participation of the Missouri Department of Natural Resources, hosted meetings to inform the local community about the Washington County Lead District - Potosi Site on the following dates: May 16, 2005; October 18, 2005; June 7, 2006; and October 24, 2006. Fact sheets were mailed to invite the local community to site meetings and to inform them about site activities as follows:: May 2005; October 2005; May 2006; September 2006 and September 2007. Overall, the public has been very supportive of EPA actions taken at the site. ------- SITE REPOSITORY Washington County Library Superfund Records Center 235 East High Street 901 N. 5th St. Potosi, MO Kansas City, KS 66101 Mail Stop SUPR (913)551-7166 REGIONAL CONTACTS SITE MANAGER: E-MAIL ADDRESS: PHONE NUMBER: COMMUNITY INVOLVEMENT COORDINATOR: PHONE NUMBER: E-MAIL ADDRESS: STATE CONTACT: PHONE NUMBER: Bruce Morrison/SUPR/R7/USEPA/US Morrison.Bruce@EPA.GOV (913)551-7755 Dianna Whitaker (913)551-7598 Whitaker.Dianna@EPA.GOV Valerie Wilder (573)751-7880 MISCELLANEOUS INFORMATION STATE: MO A78D CONGRESSIONAL DISTRICT: 8th District EPA ORGANIZATION: SFD-SPEB MODIFICATIONS Created by: Bruce Created Date: 02/14/2008 10:11 AM Morrison/ SUPR/R7/U SEP A/ US Last Modified by: Bruce Last Modified Date: 12/22/2008 11:28 AM Morrison/ SUPR/R7/U SEP A/ US ------- |