DIA spokesman Jeff Green calls this "an embarrassing situation."
Green says the alarm system was working when a pump at a lift station failed around 7 p.m. on Tuesday. It sent sewage heading toward Third Creek which feeds into Barr Lake. Barr Lake provides drinking water for parts of the metro area.
"Our investigation has shown that the audio, the speaker, was turned off. So we're investigating how that could have happened, but again also putting in procedures to make sure it doesn't happen again," Green said.
The alarm also has a visual component, but that was also missed.
"There appears to have been oversight in the notice. There is a message that would pop up on a computer screen, again it's on a screen that's not - it's in a room that's manned 24-7, but there's a lot of screens in the room, and that particular screen there isn't somebody sitting, it's not like a work station where somebody sits there and looks at it during an entire shift, which is why we have the audio backup," Green said.
He says the investigation into exactly how this happened will continue.
Green says the sewage spill is much smaller than first thought. Engineers at the airport estimate 330,000 gallons of raw sewage spilled from the lift station, not the 1 million originally thought.
Green says early test results from three different samples show no bacterial contamination flowed downstream. He also says at the time of the spill, O'Brien Canal was already being diverted from Barr Lake and the sewage likely never reached the lake.
DIA Aviation Manager Kim Day says testing will continue through the weekend to make sure there is no contamination, and public health officials will continue to monitor areas affected by the spill.
"Our top priority is public safety," Day said. "We are doing everything we can to protect the environment and public health."
There is concern the snow storm moving in on Friday could spread the spill. Green says the dam crews put in on Wednesday will help prevent any storm water runoff from flowing into Barr Lake.
Crews also built a second dam on Thursday at the edge of DIA property which will block any residual sewage from washing down into Third Creek.
Third Creek feeds into an irrigation canal and eventually into Barr Lake.
The airport is putting up signs to discourage people from coming into contact with the creek.
DIA has said it notified federal, state and local health departments, a farmer downstream, Farmers Reservoir Irrigation Company, Adams County and authorities at Barr Lake.
An engineer from the Colorado Department of Public Health and Environment was at the scene Wednesday.
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