The DOE and Kaiser-Hill have never denied the existence of underground contamination at Rocky Flats. They maintain that the site has been thoroughly "characterized" -- probed for radioactive hot spots based on documents, soil and water testing, and even rumors about where illegal wastes might have been hidden. They claim that all known waste trenches were remediated and that the cleanup standards were based on a broad scientific consensus about the immobility of plutonium in soil. The EPA and the Colorado Department of Public Health and Environment have both signed off on the cleanup, and the DOE maintains more than 140 groundwater, surface water and soil monitoring locations on site. Since the cleanup was completed, they say, samples collected at surface water "points of compliance" on site have met all federal and state regulations for water quality. "The contamination outside the buildings was very well catalogued. We have over 6 million data points," said Joe Legare, the DOE's cleanup manager for Rocky Flats from 1996 to 2005. "It is the best-characterized piece of land certainly in Colorado, if not in the entire West. The records were very well kept in terms of burial trenches."

There are good arguments, moreover, to support the cleanup standards. The odds of dying from strolling across the most polluted parts of the Rocky Flats site are still far lower than the odds of dying from driving in the car to get there. And the expense of cleaning the site to "background" would be huge. "If you could analyze every speck of soil, you'd remove the plutonium," said Al Hazle, the Colorado health department's liaison to Rocky Flats from 1970 to 1999, who died in 2005. "But the feasibility of doing that many samples is just -- the national budget. Can't do it." Former Colorado Gov. Richard Lamm remembered that his administration spent $16 million cleaning up uranium tailings near Grand Junction "that might have caused one death every 10 years. Now you give me $16 million. … I would immediately cover all of the uninsured people in Colorado." Even Wes McKinley believes it is impossible to make the land habitable. "The best they could do is to cap it with concrete and pray it doesn't move," he said.

Years after they worked there, many Rocky Flats workers are sick. Some have berylliosis, a fatal lung disease caused by the inhalation of dust released by the machining of beryllium bomb components. Federal law requires that the government compensate Rocky Flats workers with berylliosis, because it is unlikely that they could have been exposed to the element anywhere but on the job. But many more have cancers that they attribute to their work at Rocky Flats, and the causes of those illnesses are harder to prove. Radiation is not the only cause of cancer, and worker exposures at Rocky Flats were poorly monitored over the years. San Pietro was diagnosed with prostate cancer at the youthful age of 48, and his doctor blames it on his work at Rocky Flats. Norman Warling's father, who also spent his career at Rocky Flats, died in 2005 of a bone cancer that his doctors believed was caused by exposure to plutonium. Neither received compensation. "How many people were killed at Rocky Flats, and how safe was it? They're saying two? I'm saying there's hundreds," said Warling, San Pietro's friend and a fellow radiation monitor. "Maybe it takes 30, maybe it takes 40 years after you're exposed to beryllium or plutonium for it to kill you."

San Pietro, Warling and McKinley fear that Rocky Flats is in a latency period of sorts, and that the contamination left on site, previously under the roofs of the buildings but now exposed to water and wind, will eventually migrate into groundwater supplies and erode and blow eastward with the fierce winds that wrack the place, rendering far more than the 1,300-acre industrial site unusable. "The contamination will move," said Warling, who worked at Rocky Flats from 1974 until the cleanup concluded in 2005. Among the last workers laid off, Warling said he saw crews dump three to six feet of dirt on contaminated areas in the final days of the cleanup, rather than excavating and removing the contamination. "Rocky Flats is not cleaned up," Warling said. "It's covered up."

And that, for now, is how it will remain. My interview with San Pietro marked his last attempt to influence the course of the cleanup. The drive was long and nobody appeared interested in his underground history of Rocky Flats. "I'm giving up," he told me. A year later, the EPA certified the cleanup as officially "complete," and in the summer of 2007, the site was handed off to the U.S. Fish and Wildlife Service.