Union Pacific Railroad Co. Tie-Treating Plant

Overview

The Union Pacific Railroad Co. Tie-Treating Plant covers 83 acres in The Dalles, Oregon, just south of the Columbia River. The facility treated railroad ties with copper arsenate, creosote, and pentachlorophenol (PCP) from 1926 until 1987. Spills of treatment solutions and wastewater ponds contaminated soil and groundwater across the site. The EPA added it to the National Priorities List (NPL) in August 1990. Today, Amerities West, LLC operates a wood-treating business on the property, employing about 45 people and generating roughly $22.8 million in annual sales.

EPA has identified 20 contaminants of concern spread across soil, sediment, surface water, and groundwater. Key substances include arsenic, pentachlorophenol, naphthalene, benzene, toluene, ethylbenzene, phenanthrene, and several polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene, benzo[a]anthracene, and chrysene. Groundwater in the surrounding area supplies drinking water to more than 11,000 people within three miles of the site.

The Oregon Department of Environmental Quality (ODEQ) led cleanup planning. A Record of Decision was issued in March 1996 for the main operable unit. Cleanup methods included product removal, hydraulic containment, groundwater extraction using vertical wells, in-place bioremediation, and bioventing of soils. A removal action in October 1992 disposed of contaminated soils. A multi-layered cap covering one acre of contaminated sediments was built in 1995. A water treatment plant was installed, and topsoil cover was placed over surface soils with low-level remaining contamination. Institutional controls, such as land-use restrictions, were also put in place. Construction was completed in September 2004.

According to EPA assessments, human exposure is currently under control, meaning no unacceptable exposure pathways remain active. Groundwater migration is also under control, with contaminated groundwater stabilized and no unacceptable discharge to surface water confirmed. Operation, maintenance, and monitoring are ongoing. ODEQ's most recent five-year review confirmed that response actions continue to protect human health and the environment. However, the site has not yet achieved sitewide ready-for-anticipated-reuse status, because one or more cleanup goals or required land-use controls have not been fully met.

Community members seeking more information can visit ODEQ's dedicated website for the AmeriTies West site or consult the ODEQ Environmental Cleanup Site Information Database, which includes a Site Summary Report for the facility. Questions about the site can be directed to Community Involvement Coordinator Beth Clemons.