From The Denver Post (Bruce Finley) via the Sky-Hi Daily News:
For half a century, the arsenal at Denver’s northeast edge loomed as a secretive complex of more than 250 buildings with signs around it warning “Use of Deadly Force Authorized.” There, the Army made chemical weapons and later, Shell made pesticides. Residential and commercial development gradually encroached on the site. Today, 47 bison roam, raptors circle and badgers burrow on recovering short-grass prairie 10 miles from downtown Denver. “We’ve transformed a very highly contaminated site into a beautiful prairie landscape,” said Carol Campbell, the EPA’s assistant regional administrator handling Superfund cleanups and other officials. “Because it is something that people now can go to and enjoy, it is different from other Superfund cleanup sites.”
The Army still will be responsible for 725 acres of fenced-off land where toxic materials were consolidated and buried. Devices called lysimeters, about 6 feet beneath the clay and dirt, are supposed to verify that surface water isn’t reaching the waste. In addition, monitoring of the already-contaminated groundwater at the arsenal must continue to ensure that lethal chemicals don’t spread farther toward the South Platte River…
Once, homesteading farmers and ranchers lived here. In 1942, the Army established the arsenal to make mustard gas and blister agent to deter Japan and Germany. Then, during the Cold War, factory workers in body suits and gas masks produced thousands of tons of napalm and sarin nerve gas, which was stuffed into bomblets that were placed in Honest John rocket warheads.
Army leaders later leased the site to private companies, including Shell, which arrived in 1952 and for three decades produced chemical pesticides, such as dieldrin, that Shell sold worldwide for agriculture. The liquid waste was dumped in evaporation ponds. Solid waste was dumped into trenches. More than 600 lethal chemicals spread through the soil into groundwater.
More South Platte Basin coverage here.