South Wilbur Petroleum Site

The South Wilbur Petroleum site is petroleum releases from three properties just south of downtown Wilbur:  

• The Lincoln County maintenance facility, which has operated since the early 1930s
• The Washington State Department of Transportation (WSDOT) maintenance facility, which operated from the early 1930s until 1996 when it became part of the Lincoln County maintenance facility
• The Lincoln Mutual #3 fueling station, which operated from the 1960s through the 1980s

These parties have been identified as responsible for site contamination, known as potentially liable persons under Washington’s toxics cleanup law, the Model Toxics Control Act. However, Lincoln County is the only party working on cleanup with the Washington Department of Ecology (Ecology).

In 1995, WSDOT discovered contamination while assessing the site during facility closure. Soil sampling showed petroleum contamination, and additional investigations followed to understand the extent of the problem. WSDOT installed seven groundwater monitoring wells and 18 soil boreholes, taking samples that were positive for petroleum products. Follow up investigations by Ecology determined that the other two properties also had petroleum releases and one comingled plume was present under the three properties.

The site was ranked a one during the Site Hazard Assessment completed in 1999. Sites are ranked relative to each other on a scale of one to five. A score of one represents the highest level of concern relative to other sites, and a score of five the lowest.

Petroleum products, specifically gasoline, diesel, and benzene, toluene, ethylbenzene, and xylene, were found in soil and groundwater on all three properties.

Lincoln County completed a Remedial Investigation/Feasibility Study in 2001. The Remedial Investigation further evaluated the nature and extent of soil and groundwater contamination at all three properties. Samples were taken from the three properties and surrounding areas. Eight soil boreholes were installed, and soil samples were taken from several depths in each boring. Five of the eight borings were completed as temporary monitoring wells, and groundwater samples were taken. In addition, three samples were collected from Goose Creek where it borders the site.

The 2003 Cleanup Action Plan evaluated alternatives proposed in the Feasibility Study. Ecology selected the cleanup alternative that included removing the sources of contamination, installing engineering controls, and using enhanced bioremediation to address contamination.

The 2004 Consent Decree required the parties responsible for cleanup to complete the actions described in the plan, which were completed in 2005. The Decree described the responsibilities of all parties in implementing the Cleanup Action Plan. It also assured that work was conducted in a timely manner, in accordance with all applicable laws and regulations. The Decree included a Restrictive Covenant limiting groundwater withdrawal and use, restricting subsurface work in contaminated soil, and prohibiting activities that would affect the cleanup.

Ecology conducted a Periodic Review in 2012 to evaluate the success of cleanup. Reviews are required for all cleanup actions that include restrictive covenants. Reviewers found that additional cleanup actions were needed to further reduce petroleum contamination in groundwater. Additional periodic reviews will be required as long as institutional controls are in place at the site. 

The Cleanup Action Plan was amended in 2013, requiring more groundwater treatment at the site. Newer treatment chemicals were injected into the shallow soil near and below buildings to improve groundwater quality. The Consent Decree was amended to include the additional groundwater treatment. 

We completed the second periodic review in 2018 and determined that the groundwater treatments have not worked as quickly as was hoped due to the nature of the soil at this site. No further cleanup will be required, and regular groundwater monitoring will continue. A covenant remains in place that prohibits groundwater extraction.