A highly radioactive spill near the Columbia River in Hanford in eastern Washington is worse than was previously described.

Hanford Site, or the Hanford Nuclear Reservation or Site W, is a nuclear production complex. It was part of the Manhattan Project, and produced the plutonium in more than 60,000 weapons in the U.S. nuclear arsenal, including Fat Man, the bomb dropped on Nagasaki in 1945. Hanford was decommissioned between 1964 and 1971.

Over the decades, Hanford has been the source of many minor contamination issues. Even though it’s decommissioned and even open to tourists, it still contains 177 tanks of highly radioactive waste, mostly water used in the plutonium breeding process. (Before 1971, this waste was simply released into the Columbia river as soon as it was cool)

Between 2010 and 2013, it was discovered that the soil under Hanford 324 Building was significantly contaminated, presumably by leakage from holding tanks. The site is only 1000 feet from the banks of the Columbia, and less than a mile north of the city of Richland.

According to the Department of Energy, the contaminated soil, which contains cesium and strontium, remains so radioactively hot that direct contact could be lethal in two minutes or less. It measures at 8,900 rad per hour. Until now, the clean-up plan has been conservative, and the 324 building has been left standing to keep rain from moving through contaminated soil and taking it to groundwater or to the river.

But now it appears that the spill is more expansive than previously understood. The DOE is considering a much more involved clean-up plan, which will include tearing down the building, building a containment superstructure over the site, and then digging out all of the contaminated soil to be stored indefinitely. Details have not yet been worked out, but the DOE hopes not to repeat the storage failures that caused this spill.

The greatest danger of the spill is the potential for the highly radioactive soil to become airborne and breathed in by those living nearby.