Officials knew Manhattan Project chemicals disposed improperly at Missouri sites, documents reveal

Several moms in suburban St. Louis have been working to get toxic sites in the area cleaned up, a major undertaking to fix widespread contamination that some government officials apparently covered up for decades.

"This was the best kept secret of St. Louis. The Manhattan Project wasn't well known here, and it's still a pretty good secret here," Just Moms STL co-founder Karen Nickel said. 

Nickel formed her group alongside her neighbor, Dawn Chapman, in 2013. 

"Over the years...