ST. LOUIS (KMOV.com) -- The Metropolitan Sewer District confirms that crews found "elevated levels" of radiation in a manhole near the Salisbury Street flood wall - just north of the McKinley Bridge in downtown St. Louis.
An MSD spokesperson tells News 4 that crews detected the radiation while conducting system-wide inspections on manholes.
The manhole is adjacent to a storm water and sewage pump station, which is near the former Mallinckrodt Chemical Works facility. The facility processed uranium in the 1940s and 50s under government contracts with the Manhattan Engineer District and the Atomic Energy Commission as part of the old atomic weapons program.
The US Army Corps of Engineers is currently in the process of cleaning up contamination at the Mallinckrodt site. Sharon Cotner, the project manager for the Corps' Formerly Utilized Sites Remedial Action Program, says MSD requested help in testing manholes near the cleanup site at the Salisbury Street flood wall in May. The Corps lowered a device into manholes in the area and a reading in one manhole counted elevated levels of radiation.
Cotner says that about 2600 disintegrations per minute were detected, but that reading was not high enough to trigger more investigation. Typically, Cotner says that a reading of at least 6000 disintegrations per minute would lead to more sampling.
It's yet clear what the source of the radiation is.
"The material is not moving. So, it's not something that's going to suddenly flow into someones backyard or a creek or something. That's not the situation," said Cotner.
"It's not at a level that would even be a risk to someone who was suited up and went into a sewer like most of MSD's technicians would do."
An MSD spokesperson said more testing was underway, but the Corps says that more tests were not yet requested.
MSD says work on the manhole is suspended until the agency understands the conditions and any potential precautions that need to be taken.
The radiation was detected in a manhole that connects to the combined sewage and storm water pipe in the MSD system. Drinking water is not affected. St Louis City says the site is downstream from the water intake station and there is no threat to city drinking water.