EPA Superfund Site
COMMENCEMENT BAY, NEAR SHORE/TIDE FLATS
WA | EPA ID WAD980726368
About this site’s exposure pathways:
As of June 2025, the Commencement Bay, Near Shore/Tide Flats CERCLA site is considered Human Exposure Not Under Control.
OU 1: Isolated areas of PCB contamination in the Hylebos Waterway sediments remain in the biologically active zone of surface sediment that bioaccumulate in fish tissue. Though PCB concentrations are generally decreasing, they are still above post-remedy dredge concentrations. Evaluation of PCBs will be conducted in 2027. Dioxins were evaluated in the Hylebos waterway. Based on the data collected, EPA determined that dioxins in Hylebos Waterway surface sediments do not appear to be bioaccumulating in fish at concentrations that are of concern under CERCLA. However, there are subsurface sediments with much greater concentrations of dioxins, which if exposed may pose unacceptable risk to human and/or ecological receptors.
OU 2: In 2024, EPA completed a shoreline armoring cap repair to isolate areas where slag was exposed to the environment. In addition to the cap repair, EPA also capped approximately 100 feet of the shoreline, which was never remediated by Asarco. EPA is drafting an OMMP for the entire Breakwater Peninsula for the owner, Metro Parks Tacoma, to implement through a new agreement in the form of a UECA covenant. The covenant will obligate MPT to implement the OMMP, which will be incorporated into the covenant, to ensure that the remedy at the peninsula remains protective in the future. Site remediation at the former Asarco smelter facility is complete by Point Ruston, LLC, and the site has largely been developed. The remedy has been implemented and the site is permanently capped providing an effective barrier in isolating site contaminants. Several parcels located at the site are permanently capped but are vacant/undeveloped. EPA will continue to oversee work occurring at the site to ensure any redevelopment is implemented in accordance with the CD/SOW and ROD. Construction/redevelopment of the permanently capped but vacant/undeveloped areas could result in unacceptable risk through re-exposure of exposure pathways during construction activities. Post-completion construction monitoring plans, and other associated redevelopment plans need to be reviewed and approved by EPA.
OU 3: The extent of benzene contamination and the groundwater extraction and treatment system's radius of influence has not been fully characterized. There are no drinking water wells in the vicinity of the site. However, benzene concentrations exceed the remedial goal and its MCL, which was established after the ROD was issued. Additional monitoring wells are proposed to further delineate the benzene plume.
OU 4: EPA has remediated over 2,270 properties and 452 rights-of-way, there are 3 properties undergoing active remediation, 14 properties that refused remediation, which are covered by landscaping, and 23 properties that are located on steep slopes or in wetlands. On January 17, 2024, EPA OLEM released the “Updated Residential Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action Facilities” (2024 Updated Soil Lead Guidance), which updates the residential soil lead screening level and removal management level for the CERCLA and RCRA programs and provides additional guidance for setting residential lead PRGs and cleanup levels. On January 13, 2025, EPA finalized updates to the toxicity values for inorganic arsenic for both cancer and noncancer adverse health effects. EPA will need to re-evaluate of lead and arsenic cleanup levels and determine if additional cleanup actions are required for protection of human health from soil lead exposure. Institutional controls need to be further evaluated to protect the remedy and limit future exposure to contaminated soil left in place. Other institutional controls (community protection measures of education and outreach) are being implemented by the Tacoma Pierce County Health Department.
OU 6: Groundwater is not a drinking water source and there is no human exposure route.