Understanding the East Mission Flats Repository

KELLOGG — A local group of citizens have raised some concerns over the East Mission Flats Repository in Cataldo.

The repository, adjacent to I-90 across the highway from Old Mission State Park, has been in use since 2009 with a design to hold 40,000 truckloads of contaminated soil from the Bunker Hill Superfund Site.

The concerns over location and safety in regard to continuous water contamination and ecological damage, are all well thought out and valid concerns, given the historic nature of both the location of the repository and the superfund site itself.

Fortunately, Craig Cameron, a remedial project manager with the United States Environmental Protection Agency can put to rest any of those concerns.

With the Cataldo Flats being an active waterway, with rivers, ponds and swamplands that routinely flood in the springtime, it was seemingly a curious choice to put a heavy metals dump in that proximity, however after research it became clear that the area could be used for such purposes with minimal impact.

“The repository is designed to handle having flood water up against it for periods of time,” Cameron said. “Every few years flood water rises up and flows into the area surrounding the repository very gradually and so there is no scouring. The repository itself has a drainage feature built in to prevent material from leaving it. The repository is visually inspected on a weekly basis, and more often during flooding.”

As a result of the rampant pollution that took place for more than a century as mine waste was routinely dumped into the South Fork of the Coeur d’Alene River, constant flooding ensured that the wetlands and other areas surrounding Cataldo received a few feet of these contaminated sediments years before the repository was in place.

Because of its location and the potential environmental consequences, the repository has been strict in its compliance of EPA regulations.

“The repository has been operated in a compliant manner including washing off vehicles before they leave and use of the appropriate amount of dust suppression and water needed for compaction of the waste,” Cameron said. “Groundwater and surface water monitoring is performed on a regular basis and does not show an impact that can be attributed to the repository. EMFR, and the other repositories accepting waste from the Coeur d’Alene Basin Cleanup Project, are engineered, permanent solutions that are well-maintained and regularly monitored for safety and performance.”

Each year the repository is required to submit a thorough monitoring report, that provides readers with its findings, but besides knowing the full extent of the existing contamination prior to the construction and utilization of the repository, there is nothing to dispute the data from the annual report.

“There is some data that indicates a possible influence between groundwater and the repository, but not anything that points to a need to operate it differently or perform some kind of corrective action,” Cameron said. “As mentioned before, the whole area it is situated in has preexisting contamination and so it complicates monitoring. To address this, EPA recently had a national group of experts review the water quality data and monitoring network and they suggested some things to improve the monitoring. As a result, two new monitoring wells were recently added away from the repository. The wells will help us better understand the area it is in and will help monitor if there is a problem with the repository in the future. Some other changes include better ways to estimate when a monitoring trend is significant or surprising based on the whole data set and a plan of what triggers follow-on monitoring, geochemical modeling, or corrective action if necessary.”

For more information on the East Mission Flats Repository, contact Rene Gilbert with the EPA at 208-783-5781.