ARGONAUT MINE

As of April 2024, the Argonaut Mine Superfund site is considered “Current Human Exposure Not Under Control” (HENC). The primary exposure pathways are dermal exposure from direct contact with mine waste piles/sediment and contaminated seepage water from tailings piles near a residential neighborhood and junior high school. This exposure pathway is considered unacceptable based on EPA risk-based criteria because Arsenic concentrations are above the 100 mg/kg residential cleanup level. This level is for the 1x10-4 cancer risk level as outlined in various Health Risk Assessment documents including the 2020 Tailings area EECA. Although risk has been greatly reduced by the recent $25 Million Non-Time Critical Removal Action, additional risk remains in areas that have been investigated including residential areas.

Currently, future activities to address a portion of this residential pathway are completion of a Non-time Critical Removal Action for the residential areas starting in Spring 2025. Since contamination investigations are ongoing, no final decision on cleanup activities (ROD) has been made. EPA currently anticipates that human exposure will be under control by 2029 because all investigations will be completed and final remediation is likely to be proposed or underway. Residents will be informed of any exposure risks that may be found as part of residential soil sampling. EPA has held community information briefings in conjunction with the Jackson City Council and will continue to do so in the future.