Groundwater Operable Unit 3

INTRODUCTION

Operable Unit 3 (OU-3) addresses site-wide groundwater at the West Lake Landfill Superfund Site, which is located in Bridgeton, Mo. The site consists of several inactive landfills, including the West Lake Landfill and the Bridgeton Landfill. The site is on the National Priorities List under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980. The other Operable Units at the site are Operable Unit 1 (OU-1) to address radiologically-impacted material (RIM), and Operable Unit 2 (OU-2) to address non-radiological waste materials.

    Groundwater Operable Unit 3Previous groundwater investigations have been conducted at the site, including historical sampling events and more recent groundwater investigations and studies conducted under the oversight of the Missouri Department of Natural Resources (MDNR) and EPA.  Radiological contaminants, including radium, have been detected in certain on-site wells. While the existing data set provides important insights regarding groundwater conditions at the site, it is not sufficient to fully characterize current site conditions. The OU-3 investigations will further characterize the nature and extent of any impacts to groundwater at the site and evaluate potential future risk posed to human health and the environment for this media.

2014 U.S. GEOLOGICAL SURVEY REPORT

In 2014, the U.S. Geological Survey (USGS) issued a groundwater report that focused on radionuclides and included off-site sampling of private wells within a five-mile radius of the site. This report focused on analysis and characterization of groundwater conditions at and around the site. It examined historical data sets collected during 2012, 2013 and 2014 by EPA, the Potentially Responsible Parties (PRPs), and USGS.

The USGS report concluded it was not possible without further investigation to determine the sources of radium in groundwater at the site. USGS performed this groundwater study under an interagency agreement with EPA, and will continue to support the Agency as work begins on OU-3.

The 2014 USGS report is available online.

The OU-3 groundwater investigation will build upon the USGS report and the other previous groundwater data collected at the site.

CURRENT GROUNDWATER STATUS

Even though past sampling has detected radium in groundwater beneath the site, most residents in north St. Louis County receive their drinking water from Missouri American Water Works Company, which is required under the Safe Drinking Water Act to sample the water prior to distribution for radionuclides and other contaminants on a regular basis. Area residents can obtain water quality reports directly from Missouri American Water. The closest known drinking water wells to the site have shown no radionuclide detections above applicable drinking water standards. Additional work will be performed under the OU-3 investigation to locate and evaluate any other wells being used in the area.

NEXT STEPS

EPA will direct the PRPs to perform a remedial investigation to further characterize the extent of groundwater contamination at the site, as well as determine the range of naturally-occurring background concentrations of radionuclides. This remedial investigation is envisioned to include augmenting the existing monitoring well network with additional strategically-placed wells; periodic sampling of on-site and off-site wells; fully evaluating the area and local hydrogeology; and further studying the potential sources of radiological contaminants in groundwater. EPA will work closely with MDNR on this investigation, and expects the PRPs to perform this work pursuant to an enforceable agreement.

ADDITIONAL INFORMATION

Additional information regarding the West Lake Landfill Superfund Site is available online.

The website contains informational publications such as West Lake Updates and Fact Sheets, technical documents and sampling results, and correspondence and other documents related to EPA’s work at the site.

Interested citizens can also contact Ben Washburn (see below) to be added to EPA’s email list to receive updates.