From The Durango Herald (Peter Marcus):
The EPA-released documents include a detailed chronology of events leading to the Aug. 5 blowout, which resulted in an estimated 3 million gallons of wastewater streaming into the Animas River. An EPA-contracted team was working on reclamation at Gold King Mine near Silverton when excavation work resulted in the disaster.
Stunning photos taken of the incident document how a leak quickly turned into a flood of mustard-yellow sludge flowing into a creek then the river from a hole about 10 feet wide by 15 feet high. The leak was first noticed about 10:51 a.m. The muddy water flowed around trucks and heavy equipment used by the team, clearly taking workers by surprise as they ran for safety and to save trucks and equipment, according to a contractor’s memo of the incident. The name of the contractor was removed from the document.
As the access road washed away, the team realized that a vehicle had been parked in the line of the rushing water. The vehicle would not start following the water damage. Meanwhile, the water continued to pile up.
Some of the team left on foot to get picked up and taken to an area with phone service to notify authorities. It took more than 90 minutes for a team member to get to a location where he could notify authorities. There were no satellite phones at the site, though workers were able to use two-way radios.
Meanwhile, a Flight for Life helicopter flew overhead, photographing the alarming situation. It turned out the helicopter was not there for the incident, but instead was related to a tourist who was injured on Corkscrew Pass…
All the while, pH readings plummeted, leading the team to believe that it had caused a major water disturbance.
It took the team nearly five hours to reconstruct a temporary road to remove equipment and personnel, according to the document.
The event actually began on Aug. 4, when the team was clearing away rubble in front of the “plug” that ultimately gave way. An email released by the EPA describing the chronology states, “Because all this was unconsolidated material it was considered safe to remove, it was not buttressing the plug.
“We were constantly and carefully watching for and closely inspecting the digging for indications of the plug,” the email continues.
The document was redacted by the EPA, removing the name of the team member who sent it. He was described as an EPA on-scene coordinator.
The rock face of the wall was described as a “puzzle,” with the email stating that material had to be removed just to see the plug.
On the morning of Aug. 5, the team saw the outer face of the plug, which appeared dry and solid, but they couldn’t get close because of dirt from overhead. There was no change in water flow at the time, according to the email.
“Keeping in mind that the mine should be assumed to be full of water – that is backed up to the top of the plug or higher – we did not want to get anywhere close to the top of the plug,” the email from the team states.
The team needed to determine where the bedrock was to plan a safe approach to the plug, and that is where the problematic excavation work happened.
When the leak was spotted, the team first assumed it was a rock spring.
“On as close inspection as I dared, I could see that the clear water was spurting up not down. A couple of minutes later red water began to flow out from near that spot. …” the email states. “In a couple of minutes it became obvious there was a lot of water coming.”[…]
“EPA is establishing a longer term watershed monitoring strategy for the surface water and sediments that have been affected by the Gold King Mine spill to identify potential long-term impacts working closely with state and local officials,” EPA officials said in the release.