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Boeing Fabrication Auburn Plant

Remedial Investigation

Since the 1990s, the site has undergone ongoing monitoring. The results were shared with the public as they became available as part of a multi-year study, called the Remedial Investigation (RI). These findings are posted below.

Draft Remedial Investigation (RI) Report

The Draft RI Report uses the findings from the entire investigation to define the nature, extent, and magnitude of the contamination in order to identify the best methods for cleanup. For more information about the Draft RI Report you can:

What is groundwater?   en español

“Groundwater is the water found underground in the cracks and spaces in soil, sand and rock. It is stored in and moves slowly through geologic formations of soil, sand and rocks called aquifers.” Source.

Graphic showing how groundwater systems work. 

Groundwater Results

Boeing has installed over 260 groundwater monitoring wells in Algona and Auburn since 2009. Wells vary in depth from a few feet to approximately 100 feet below the ground surface. The deepest wells are screened just above the Osceola Mudflow, which is a confining layer. When sampling began, the extent of historical releases of chemicals to the groundwater was unknown. Since that time, Ecology has directed Boeing to install groundwater monitoring wells to define the size, locations, and concentrations of chemicals present in two groundwater plumes. The results of the investigation have identified two locations where TCE was released on the Boeing Auburn facility. Those locations are thought to be the source of the two contaminated groundwater plumes.

Step-by-step testing process

Groundwater testing is a step-by-step process, where wells are installed increasingly further from the source of the contamination to determine where the chemicals are present. New wells are placed approximately 500 to 1,000 feet out in the direction of the groundwater flow. Each time new wells are installed, it takes about six months to analyze the data. If contamination is found, Ecology determines where additional wells are needed. By starting from the source and sampling outward, data collected along the way helps confirm the source location and the extent of the contamination.

Why we study groundwater

Understanding the concentration of chemicals in the groundwater is important because groundwater is often connected to surface water.

For example, Ecology directs Boeing to investigate the surface water to determine if contaminated groundwater has been discharging to surface water within and near the site. Visit the surface water results page for more information.

Groundwater contaminants can also affect air quality if the contaminants pass (evaporate)from the groundwater to the air, as can happen with TCE. This can lead to a process called vapor intrusion in which TCE vapors can enter homes or businesses. Ecology directed Boeing to investigate air quality in both northern residential Algona, and the commercial districts of Algona and Auburn. Those areas were sampled because contaminants were found in groundwater nearest the surface (shallow zone) and therefore more likely to pass into the air. Visit the air quality results page for more information.


The most recent sampling of the entire groundwater monitoring network occurred in June 2015. The results from that work will be posted when they are submitted in mid-summer of 2015.

The following resources provide more information about groundwater sampling to date: