Public comments wanted: State to select cleanup plan for Colfax Site

The Washington State Department of Ecology is inviting public comment about the Colfax Petroleum Contamination site.

This map provided by the State Department of Ecology shows the contamination site.

The site lies along the east side of North Main Street at the intersection of East Tyler and East Harrison streets. It is approximately 1,000 feet south of the Palouse River and east of the south fork of the Palouse River.

The site includes several parcels, currently or previously occupied by gasoline stations. Petroleum leaks from operations at the sites contaminated soil and groundwater, requiring further investigations and development of cleanup options.

A draft of the cleanup plan provides details about Ecology’s selected cleanup action and how the cleanup will be conducted. A state checklist considers potential environmental impacts before beginning the cleanup.

The Colfax Grange Supply Company, Inc., CHS, Inc., and Time Oil Co. are known as potentially liable companies responsible for cleanup at the site. These three companies made an agreement with Ecology in 2007 to begin cleanup.

Since 2007, additional potentially liable companies have been named because of property transactions, dissolving businesses and new ownerships. They have been combined into a group called the North Colfax group, and include PetroSun Fuel, Inc. (now Pacific Convenience & Fuel, LLC), TOC Holdings Co. (formerly Time Oil Co.), CHS, Inc., and Colfax Grange Supply Company, Inc. make up the group.

The site is made up of the following properties:

The Colfax Grange Supply is located at 105 East Harrison Street. It includes a hardware store and warehouse. Historically, a gas station was located at the intersection of Harrison and Main streets. Petroleum contamination was discovered in soil under the site during an investigation in 1999, according to Brook Beeler, Ecology communications manager.

The Cenex Cardtrol property is bordered on the north by East Tyler Street, to the west by North Main Street, to the south by the railroad tracks and to the east by an unopened City of Colfax right-of-way. The Cenex property includes the cardtrol facility owned by the Colfax Grange. Colfax Grange Supply Company is the legal owner of the cardtrol facility located at 102 East Tyler Street.

In 2004, CHS, Inc., delivered unleaded fuel to the Colfax Grange’s cardtrol. During the fuel delivery, CHS, Inc., overfilled the tank, and petroleum spilled on the ground. A section of the concrete cover and underlying soil where the spill occurred were removed. New groundwater monitoring wells were installed to monitor any impacts to groundwater. Samples from these wells showed petroleum in the groundwater in 2004, Beeler said.

The PetroSun/Time Oil property, Cougar Mart, is at 804 North Main Street and includes a gasoline station convenience store with a pump island canopy.

Petroleum releases occurred at the site as a result of past gas stations businesses. The first release was discovered in 1999 when the Time Oil Co. upgraded the gasoline convenience store known as Food Mart. Petroleum was found in soil and groundwater during the upgrade of the facility. Since 1999, several cleanup actions were done by Time Oil and Colfax Grange.

In 2007, a study was conducted to determine what contaminants remained at the site and where they were located, according to Beeler.

Results from the study confirmed elevated levels of petroleum product in soil on all three properties. Petroleum products included gasoline, diesel and heavy oils, she said.

Results from groundwater sampling conducted from September 2009 to May 2011 showed four groundwater monitoring wells exceeded state standards for petroleum. Plumes of petroleum were found under the site. A plume is a mass of contamination underground mixed with groundwater.

Cleanups called interim actions were conducted on the PetroSun/Time Oil and Cenex Cardtrol properties. As a result, the observed petroleum plumes under the site shrank significantly. One groundwater monitoring well continues to show signs of petroleum contamination within the site boundaries. This groundwater monitoring well was expected to meet groundwater standards by the end of 2012. Another well still is showing contamination and will continue to be monitored, Beeler said.

Currently, Ecology reported there are no impacts to drinking water, and there are no significant risks from contaminant-related vapors at the site.

Ecology developed a draft of an action plan based on information from the study reports.

The public can review and comment on the cleanup plan. Ecology will consider public comment and make any changes in the plan the department deems appropriate.

Ecology selected the first of three alternatives which include, monitored natural breakdown of any contaminants as the cleanup for all three properties at the site. The cap made of asphalt and concrete will prevent surface water from leaching and potential contamination of groundwater.

The alternative includes: maintenance of an asphalt and concrete cap that confines contamination at the PetroSun/Time Oil and Cenex Cardtrol properties; installation and maintenance of an asphalt and concrete cap at the Colfax Grange Supply property; each property will include monitored natural breakdown.

Monitored natural breakdown allows contaminants to naturally decrease over time. Additionally, institutional controls such as a management plan or contaminant contingency plan for remaining petroleum in subsurface soil will be used. Groundwater monitoring will document that the natural breakdown is occurring.

This plan also includes additional protection after the cleanup through use of groundwater monitoring and periodic reviews to evaluate progress of the natural breakdown. A restrictive covenant, also called an environmental convenant, will be used on each property to limit how the properties may be used.

Cleanup also includes financial assurance from those liable that addresses potential future cleanup improvements, if necessary. Detailed evaluation of cleanup alternatives is found in Ecology’s plan.

After review of the environmental checklist and other site-specific information, Ecology determined the actions to address contaminants in soil and groundwater will not have a significant adverse impact on the environment.

Comments are accepted now through March 7. Submit comments to Washington Department of Ecology, Doug Ladwig, Site Manager, 4601 N. Monroe St., Spokane, WA 99205.

Ecology will respond to comments submitted by the March 7 deadline. A summary of the responses will be sent to the people who submitted comments. If no changes are made, the documents become final and the cleanup moves forward according to Ecology’s plan.