Protecting Human Health and the Environment
About the Kerr-McGee Chemical Corp – Soda Springs Plant Superfund Site
The Kerr-McGee Chemical Corp – Soda Springs Plant Superfund Site (the Site) was contaminated by nearly 40 years of vanadium production operations.
In 1989, the contamination in groundwater led the U.S. Environmental Protection Agency (EPA) to add the Superfund site to the National Priorities List (NPL) of federal Superfund sites. The NPL is the EPA list of the worst hazardous waste sites.
The Superfund designation means the remediation must follow the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) process that EPA uses to clean up Superfund sites. CERCLA is also known as Superfund.
The Multistate Environmental Response Trust (Multistate Trust) is performing investigations and remediation of the Site under EPA oversight and in consultation with the Idaho Department of Environmental Quality (IDEQ).
Overview of Investigations and Remediation Planning and Progress
Milestones Achieved to Date
In 2011, the Multistate Trust accepted responsibility for owning and managing the Site in Soda Springs as part of the Tronox bankruptcy settlement. Since then, the Multistate Trust has implemented a number of environmental actions, investigations, and other activities, including the following:
Completion of the Domestic Well Survey and Water Quality Sampling, 2015
Completion of the Waste Removal and Initial Site Cleanup, 2016
Completion of the 10-Acre Pond Time-Critical Removal Action, 2018
Completion of Building Demolition, Waste Excavation, Site Regrading, and Repository Construction, 2019
Completion of the Supplemental Remedial Investigation, 2020
See documents page for more volumes
Completion of the Human Health Risk Assessment (HHRA), 2020
Completion of the Screening Level Ecological Risk Assessment, 2020
Completion of the Focused Feasibility Study, 2022
Completion of the Proposed Plan, 2023
Supporting EPA issuance of the Record of Decision (ROD) Amendment, 2023
Initiating the Groundwater Remediation System pilot study, 2023 (ongoing)
Current Activities and Work
In November 2023, EPA issued a Record of Decision (ROD) Amendment, selecting the revised remedy for the Site cleanup approach. The ROD Amendment included starting active groundwater remediation through a pilot study to evaluate, select, and optimize the best ways to clean up groundwater at the Site.
The Multistate Trust has continued implementing the multi-year pilot study for in-situ and ex-situ groundwater treatment. The Source Area Groundwater Remediation System pilot study began in 2023 and includes both laboratory and field scale testing to select the best performing treatment amendments, optimize dose, and test amendment delivery and treatment techniques.
Groundwater treatment is ongoing through seasonal field implementation while more permanent infrastructure is being designed. Field trials are informing the larger-scale pilot study design. Once design of the larger-scale pilot study is complete, construction of the remediation system will begin. The system design was advanced in 2025 and is planned to be finalized in 2026.
The Multistate Trust also continued supporting the petition to IDWR to establish an Area of Drilling Concern (ADC) around and near the Site, The ADC was established in August 2025 and is an institutional control on groundwater exposure.
Our Beneficiaries and Regulatory Agencies
In Soda Springs, the Multistate Trust is working in collaboration with its federal and state governmental beneficiaries for the Site:
the United States, represented by EPA and the U.S Department of Justice (DOJ)
the State of Idaho, represented by IDEQ
EPA is also the lead regulatory agency for the Site, and IDEQ is the non-lead agency.
In EPA’s role as lead agency, EPA approves Site-specific remediation plans and activities and the hiring of contractors to perform environmental activities at the Site. In its role as beneficiary, EPA approves the Multistate Trust’s work plans and annual environmental budgets, in consultation with IDEQ.
The sale, transfer, or disposition of any portion of the ±547-acre Multistate Trust property must be approved by EPA, in consultation with DOJ, and IDEQ.
Our Commitment to Community Stakeholders
The Multistate Trust and its beneficiaries recognize that the City of Soda Springs and residents near the Site have been impacted by the Site.
The Multistate Trust team remains dedicated to protecting and engaging our neighbors and the surrounding community as we remediate the Site and plan for its safe, beneficial reuse for future generations.
Learn more about our stakeholder engagement efforts at Community and Reuse.