What is the go-forward process from here?

The Feasibility Study (FS) was approved by EPA on June 17, 2021.

Next, EPA will issue a preliminary plan with its preferred options for site remediation. The preliminary plan is anticipated approximately six months after EPA’s approval of the FS.

EPA will take public comment on the preliminary plan and its preferred options. Following the comment period, EPA will issue a Record of Decision (RoD), which contains the final, approved site remedy plan.

Do the residents of Columbia Falls have a say in future remedial decisions?

CFAC has closely involved the residents of Columbia Falls throughout the process.

Residents and other stakeholders will have the opportunity to comment on EPA’s preliminary plan and preferred options prior to the issuance of its Record of Decision (RoD), which will contain the final site remedy plan.

What is a slurry wall?

Slurry walls are subsurface barriers that impede or stop groundwater flow.

The subsurface wall would be designed to encompass the two landfills that are impacting groundwater. We anticipate it would be between 2 to 4 feet thick and between 100 to 125 feet deep, designed to encompass the LDU1 source area and prevent impacts to groundwater.

Slurry walls were a component of the selected remedies for 86 other Superfund sites. EPA and National Research Council have both independently conducted studies to verify the effectiveness of slurry walls in achieving remedial action objectives.

Would a slurry wall be a long-term solution to remediate the site?

Yes, we believe that a slurry wall is a long-term solution that we do not anticipate needing to be replaced.

Slurry walls are a proven and effective remediation solution that have been successfully deployed across the country.

The slurry wall alternative is the highest-ranking alternative identified in the Feasibility Study approved by EPA. The ranking was done in accordance with EPA rules and guidelines.

How will you know whether the remedial action is working?

The highest ranked alternative includes monitoring wells both inside and outside the slurry wall.

Additionally, once an alternative is selected and implemented, the Superfund process requires EPA to perform a comprehensive review every five years to ensure the implemented remedy continues to protect human health and the environment and complies with all applicable laws.

What will happen to the site after the clean-up process is complete?

The Superfund site encompasses approximately 1,300 acres, most of which were used during the operating period.

CFAC is remediating this area for the purpose of future industrial or commercial use.