Imperial Refining Company ran a crude oil refinery in Ardmore, Oklahoma from 1917 to 1934. After the facility closed, waste piles, pits, and water impoundments left the soil and sediment contaminated with hazardous chemicals. EPA added the site to the National Priorities List in July 2000, triggering a formal federal cleanup process.
The main contaminants of concern are arsenic and benzo[a]pyrene, both found in soil and sediment in the source area of the site. These substances posed unacceptable risks to people and ecological resources through ingestion, direct contact, and exposure through contaminated sediment. Polycyclic aromatic hydrocarbons (PAHs) and metals were also identified as part of the broader contamination picture.
EPA selected a cleanup plan in December 2007 and updated it in February 2009. Workers excavated about 104,500 cubic yards of contaminated waste and soil, plus 1,700 cubic yards of sediment, and sent the material to an off-site landfill. Where contaminated material remained on site, crews installed a clay barrier to block contaminant movement and limit exposure. Institutional controls now restrict the property to industrial uses. Physical construction wrapped up in December 2012, and EPA deleted the site from the National Priorities List in September 2013.
Today, human exposure is under control and groundwater migration is stabilized, with no unacceptable discharge to surface water. The Oklahoma Department of Environmental Quality (ODEQ) handles ongoing operation and maintenance, including regular monitoring for erosion and vegetation loss. Five-year reviews completed in 2013, 2018, and most recently in June 2023 have confirmed the remedy continues to protect public health and the environment. The next review is estimated for June through August 2028.
Community members with questions can contact the EPA Community Involvement Coordinator or the Remedial Project Manager. For state-related questions, contact ODEQ.
