MacMillan Ring Free Oil

Overview

MacMillan Ring Free Oil is a 100-acre former refinery in Norphlet, Arkansas, that operated from 1929 to 1987 and later hosted chemical manufacturing until 2007. The site sits next to a residential subdivision and a public school. It was added to the National Priorities List in May 2014, and cleanup has unfolded over several decades.

The main contamination concerns are petroleum-related. Groundwater testing in January 2020 found a layer of light non-aqueous phase liquid (LNAPL), which is a free-floating hydrocarbon, along with dissolved petroleum hydrocarbons in shallow groundwater. Earlier samples from 2011 and 2012 detected benzene and naphthalene above screening levels, but samples from 2015 and 2020 showed those chemicals below risk levels. Diesel-range petroleum hydrocarbon concentrations dropped more than 80 percent over nine years at the most contaminated well. An ecological risk assessment found surface soil contamination with lead and mercury in an industrial area, and one sediment sample exceeded risk levels for polycyclic aromatic hydrocarbons. Asbestos-containing insulation bricks were also found on a two-acre area of the site.

The EPA and site parties completed several removal actions over the years. In the early 1990s, free liquids were removed from impoundments and treated on-site. In 2009, the EPA removed tanks holding anhydrous hydrofluoric acid. In 2021, about 5,900 tons of asphaltic oil-contaminated soil and 150 tons of contaminated steel were excavated and hauled off-site. From November to December 2022, the EPA completed removal of the asbestos insulation bricks, with soil samples and air monitoring all below action levels during that work. The EPA signed a Final Close Out Report in June 2024 documenting completion of all CERCLA cleanup activities.

On September 29, 2020, the EPA issued a Record of Decision calling for no further action under CERCLA, finding that current and future site conditions in soils, sediment, and surface water pose no unacceptable risks. However, the site remains on the NPL because LNAPL and petroleum impacts are still present. Petroleum assessment and removal work continues under Oil Pollution Act guidance. The EPA plans to delete the site from the NPL once that petroleum cleanup is finished, with deletion anticipated in 2025.

Community members with questions about the site can contact the EPA Community Involvement Coordinator or the Remedial Project Manager. Site documents are available at the Norphlet Public Library in El Dorado, Arkansas.