Hill has until April 2 to give the state its response. And, facing $13,000 a day in fines, the base is working on its explanation of why the spill was not reported, as required by law, and why the mercury from discarded boiler parts was not properly cleaned up and disposed of right away.
Investigation reports from both Hill and the state detail what appears to be a deliberate effort to hide mercury that leaked during a boiler retrofit in 2006-07.
At the time, untrained workers collected the elemental mercury in two, 16-ounce plastic bottles and a plastic Western Family juice bottle. And, contrary to common-sense practices, they used vacuums to suck up the mercury.
The crew included the still-unnamed whistleblower who raised the alarm about the mishandled mercury last October and triggered state, federal and military investigations. The manager who ordered the improper cleanup also has not been publicly identified.
A criminal investigator from the U.S. Environmental Protection Agency and Hill representatives joined three state inspectors last Oct. 18 in checking out the whistleblower's claims during a five-hour inspection in and around four buildings.
At Building 278, a metal structure containing shelves of industrial equipment parts and supplies, they found one container tucked in the cavity between an I-beam and a wood plank. In the opposite corner, they found another plastic bottle hidden behind an I-beam that itself was blocked by shelving and a cardboard box.
Investigators collected samples from the unlabeled bottled for testing. The building was then locked up, as was the fenced area surrounding it, so Hill could come back and test soil outdoors and a spot where the mercury had evidently leaked.
Investigators found a third bottle the juice container in Building 1904, where they had been told to look for a bottle of mercury that had been buried outdoors and recently brought inside.
"A container was found on one of the shelves behind a plastic bag," the state's report said. "The mercury was in a Western Family juice container [approximately 64 oz.] and was about 1/2 full."
Investigators were careful not to handle the materials until they had donned protective gear.
At a third building, investigators bagged samples from a vacuum and a shop vac. They also scoured a boiler room in another building where mercury was reportedly hidden between walls but found nothing.
After removing samples for testing, the investigators dropped off the mercury at Hill's hazardous waste office, where it was finally added to the 200-plus waste streams routinely handled at the base under a state permit.
Anderson said he was surprised the base's award-winning cleanup team wasn't called in from the start. "We were baffled," he said.
EPA's criminal enforcement office in Denver did not return a call seeking information about the status of its investigation this week. And Hill spokeswoman, Barbara Fisher, had little to add.
"We're kind of limited in what we can say because of the investigation," she said.
Meanwhile, the Hill report, a voluntary corrective action plan submitted to state regulators in January, concluded that lingering emissions in the two buildings were no cause for concern.
"No further action is recommended for this area," the investigation report says repeatedly.
The whistleblower's attorney, Scot A. Boyd, said he's curious what's next, now that the cover-up has been exposed.
"We want Hill to be a good neighbor," he said. "And we want them to make sure that something like this never happens again."