Cleaning up the Everett Smelter lowland area

We finalized the Cleanup Action Plan in November 2016 for the lowland area of the Everett smelter site, east of East Marine View Drive. We’ll be cleaning up 14 areas in the lowland section. Cleanup methods include removing soil and capping (covering the soil with a material that prevents people being exposed or rainwater soaking in). In some areas, we will require institutional controls — measures taken to limit or prohibit activities that might result in exposure to contamination. In other areas, we will allow natural processes to reduce the contamination, while monitoring surface water and groundwater quality to confirm that it's working.

Cleanup is phased

  • We finished cleanup in area A1 in 2018.
  • We disconnected the underdrain system in area C5 during the development of parcels in 2019.
  • Ecology is partnering with the City of Everett to install a lining inside the cracked pipes to prevent contaminated groundwater from entering the Snohomish River. This work is happening in 2023 and 2024. 
  • Ecology also partnered with the city to install fencing along E Marine View Drive (area C2 and C3) at the top of the steep slope above the railroad tracks. This fencing limits access to contaminated soil on the steep slope.

Cleanup Action Plan for the lowland area

We found that arsenic, lead, and mercury are the main contaminants in the lowland area. These contaminants exist in soil, shallow and deep groundwater, and in limited areas of the sediment below outfalls along the shoreline. The contamination must be addressed because it exceeds limits allowed by the state’s cleanup laws.

The cleanup site is divided into Uplands (residential) and Lowlands cleanup areas. The two areas are on different cleanup schedules.

The Cleanup Action Plan addresses 14 contaminated areas in the lowlands part of the site. We plan to use different cleanup technologies, and we may use more than one technology at some locations.

Cleanup methods

  • Removal of contamination is planned for A1 and A2. Workers will excavate contaminated material and transport it offsite for disposal at an approved facility.
  • Capping of contamination is planned for areas B1–B3, and C5. A natural or synthetic material is installed over contaminated soil to prevent rainwater from entering the contaminated soil. This reduces the potential for human exposure.
    • New caps will be installed at B1 and B2
    • Existing caps will be maintained at B3, C5, and C6
  • A permeable reactive barrier will be installed at B2. The barrier is created by injecting chemicals into the ground. The chemicals form a “wall of treatment” that reacts with arsenic as it passes through the treatment area. Arsenic is then drawn out of groundwater and into the soil where it stays in place.
  • Institutional controls will be used at C1–C3, C6, and D1–D4. These include fences, permit requirements, restrictive covenants, and zoning regulations to minimize the potential for human exposure. These controls do not physically change the site or reduce contamination levels.
  • Monitored natural attenuation will be used at C1, C6, and D1–D4. The plan is to monitor the water quality of surface water and groundwater to confirm that natural processes are reducing the contamination.

All sites will be monitored after cleanup actions are completed to confirm that the cleanup remains effective. We prioritize removal of contamination sources and plan to phase in the work as funding allows.


During the smelter operation, the lowland area was an undeveloped flood plain/tide flats area. In 1914, after the the smelter facility closed, Weyerhaeuser acquired most of the land in the lowland area. Over the years, Weyerhaeuser constructed and operated a large wood products manufacturing complex.

When Weyerhaeuser decommissioned its timber industry operations within the lowlands area in the 1980s and 1990s, it provided a good deal of environmental data. Ecology oversaw cleanup of contamination from the timber operation on the three former Weyerhaeuser properties that are located within the Everett smelter lowland area, see "Related Links" below.

This contamination is not being addressed in our Everett smelter lowland area cleanup plans. The cleanup activities for the Everett smelter site will only address metals contamination (mainly arsenic and lead) from the smelter operation.

Using the Asarco settlement funds, Ecology investigated the nature and extent of the smelter contamination in the lowlands area and reported it in the Supplemental Remedial Investigation Report. Cleanup alternatives were then developed and evaluated in the Feasibility Study report. Both reports were finalized in February 2016. You can view these reports in our online document repository.