The Dixon Iron and Metal Company (DIMCO) is a former scrap metal recycler that operated from the 1940s until 2017. DIMCO is located at 78 Monroe Ave in Dixon, IL, adjacent to the Rock River, residential, commercial, and industrial properties. In 2017 and 2018 the City of Dixon/Illinois EPA conducted soil, groundwater, and soil vapor sampling as part of a Brownfield Redevelopment Assessment. In 2019, EPA supplemented the City of Dixon/Illinois EPA sampling with additional soil sampling, groundwater investigation, and Rock River sampling (i.e. porewater, surface water, and sediment). The property was acquired by the City of Dixon in 2019.
Results of the combined City of Dixon/Illinois EPA/EPA sampling indicated metals in soil (predominantly lead) above EPA Removal Management Levels (RMLs), polychlorinated biphenyls (PCBs) at or above Toxic Substances Control Act (TSCA) concentrations, and lead in soil above Toxicity characteristic leaching procedure (TCLP) toxicity levels. A diesel/PCB light non-aqueous phase liquid (LNAPL) mixture was found in groundwater at a monitoring well closest to the Rock River. Pore-water sampling in the Rock River indicated the presence of PCBs. In addition, PCBs were found above TSCA concentrations in Rock River sediment adjacent to the Site. Container sampling at the site indicate at least one container with a pH concentration of 0.
The Superfund Division Director signed an action memorandum on May 29, 2019, to document approval to conduct a time-critical removal action. The time-critical removal action will include removal of lead contaminated soil above 400 milligrams per kilogram (mg/kg) to 24-inches, PCB contamination above 25 mg/kg within the first 24-inches, and PCB contamination above 50 mg/kg to groundwater. PCB contaminated soil above 25 mg/kg will be capped. An Addendum to the May 29, 2019 Action Memo was signed on October 16, 2019, allowing for mitigation of the LNAPL in the northwest corner of the site via source removal and interceptor trench.
Removal activities started on August 12, 2019 and temporary halted on December 20, 2019. Activities resumed on June 16, 2020 and lasted until August 7th, 2020. Efficacy monitoring in the interceptor trench is on-going.