GSI staff conducted a remedial investigation and implemented remedial actions at a former locomotive maintenance site that was contaminated with chlorinated solvents.


Weyerhaeuser is a wood fiber company that owns property near Klamath Falls. The site used to be home to a railroad that hauled trees from the forest to three different mills. During the mid-20th century, locomotives were cleaned using chlorinated solvents, leading to contaminated soil and groundwater around the maintenance shop. GSI’s cleanup work at the site included:

  • Remedial investigation and feasibility study
  • Interim remedial actions
  • Technical support for litigation related to contaminant migration offsite
  • Implementation of the Oregon Department of Environmental Quality-approved remedy

GSI’s Solution

Remedy construction and operation started in 2000 and consisted of upgrading and expanding the existing soil vapor extraction system and installing a groundwater extraction and treatment system. The groundwater treatment system consisted of air stripping for the chlorinated solvents and advanced oxidation for the solvent stabilizer. Remedy operations ended in 2008.

The cleanup process initially included natural biological processes (natural attenuation). However, this initial remedy did not adequately address the spread of contamination in groundwater. As a result, in 2012, GSI applied an interim action of a cometabolic bioremediation. Additionally, 200 poplar trees were planted at the trailing edge of the groundwater plume to facilitate direct uptake of the contaminated shallow groundwater plume. Effective waste management reduced costs significantly while maintaining regulatory compliance.