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EPA in Missouri

Southwest Jefferson County Mining Superfund Site, OU-4 - Big River and Floodplain, Jefferson County, Missouri - Fact Sheet, December 2016

EPA Region 7 to Host Public Availability Session

The U.S Environmental Protection Agency (EPA) Region 7 will host a Public Availability Session to discuss and answer questions about the ongoing Remedial Investigation and Feasibility Study (RI/FS) for the Southwest Jefferson County Mining National Priorities List (NPL) Superfund Site, Operable Unit 4 (OU-4), Big River and Floodplain.

The session will be held:

Tuesday, Dec. 13, 2016
6:00 to 8:00 p.m.
Hillsboro Community Civic Club
Jefferson County Fairgrounds
10349 Business 21

Hillsboro, MO 63050

For reasonable accommodations at this Public Availability Session, please contact Jonathan Cooper toll-free at 1-800-223-0425 or at


The Southwest Jefferson County Mining National Priorities List (NPL) Superfund 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 the county. In residential properties, this material has been used as topsoil, fill material, and aggregate for roads.

EPA and Missouri state agencies have been addressing lead-contaminated soils in Jefferson County for more than a decade.


The Southwest Jefferson County Mining Site is separated into eight Operable Units (OUs). OU-1, OU-2, and OU-3 include the residential properties. OU-4 includes the Big River and floodplain, OU-5 includes groundwater, OU-6 is the Valles Mines area, OU-7 is the rail lines, and OU-8 consists of the mine waste areas. EPA works on the various operable units on a priority basis, based on the potential for human health and environmental risks.


As of August 2015, in support of OU-1 through OU-3, EPA has collected soil samples from 2,902 residential properties within site boundaries and has cleaned up (remediated) 551 of these properties. The remedial action phase is the actual construction or implementation of a Superfund site cleanup that follows the remedial design. The cleanup (remediation) consists of excavating and removing contaminated soil and gravel from affected properties, and replacing the excavated material with clean fill and vegetative cover, including sod and hydro-seed.

Sampling and cleanup (remediation) work is ongoing and is expected to continue until the remedial action objectives are met. Reports for these actions can be found at the site repositories listed at the end of this document.

EPA Region 7 staff and contractors have continued to collect soil and groundwater samples from residential properties. If your property has not been sampled, and you would like to have your soil and/or groundwater analyzed, please contact EPA.

EPA is currently conducting Remedial Investigation activities at OU-4 and OU-8. Additionally, EPA has completed a dam stabilization project at the Rockford Beach Park, and is conducting a pilot project along the Big River at Brynes Mill City Park, including removal of contaminated soil and replacement with clean material. EPA is also planning a pilot project near the Mammoth River access point.


In addition to the remediation of lead contaminated soils, EPA is also working with the Missouri Department of Natural Resources and the Missouri Department of Health and Senior Services to increase public awareness to protect residents from exposure to heavy metals, and is collaborating with the community to safeguard future residential development and protect remediated residential properties from lead recontamination.

Health and fish advisory signs are being placed along access points to the Big River where elevated levels of lead in the sediment have been detected.


EPA is currently conducting a Remedial Investigation (RI) at OU-4 that includes the Big River and floodplain to determine the full extent of mining-related metals contamination and to evaluate human health and ecological risk.

Upon completion of the RI, EPA plans to initiate a Feasibility Study (FS) to evaluate remediation alternatives. Upon completion of the FS, a Proposed Plan will be presented to the public describing the evaluated alternatives and the proposed remedy.

EPA is committed to promoting communication between citizens and the agency. EPA will continue to engage the public in various activities designed to inform and involve community members throughout the decision-making process. Prior to any site cleanup decisions, EPA will present findings of the investigation to the community and solicit public comments about the next steps.

As a part of this process, EPA will provide recommendations for cleanup to include costs, and will work to identify potentially responsible parties (PRPs) responsible for the contamination. PRPs could be required to conduct or pay for the cleanup.


The AR file includes EPA decision documents about the response actions at the site. It is available for review during normal business hours at the following locations:

Site Information Repositories

EPA Region 7 Records Center
11201 Renner Blvd.
Lenexa, KS 66219
De Soto Public Library
712 S. Main St. 
De Soto, MO 63020


The AR is also available through an online repository at


Questions and requests for information about the site can be directed to:

Elizabeth Kramer
Community Engagement Specialist
EPA Region 7
11201 Renner Boulevard
Lenexa, KS 66219
913-551-7186 or toll-free at 1-800-223-0425
Preston Law
Remedial Project Manager
EPA Region 7
913-551-7097 or toll-free at 1-800-223-0425
Greg Bach
Remedial Project Manager
EPA Region 7
913-551-7291 or toll-free at 1-800-223-0425


Visit EPA’s lead website and the Agency for Toxic Substances & Disease Registry’s ToxFAQs™ Fact Sheet.