By Michael Roberts
By Amber Taufen
By Patricia Calhoun
By William Breathes
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By Melanie Asmar
By Michael Roberts
By Michael Roberts
Detection limits are the levels of contamination that a lab detects in samples sent for analysis. Normally, laboratories provide their clients with the actual results of their analyses, as well as such qualifying information as detection limits and counting errors. So, for example, if the detection limits for plutonium were set at 50 picocuries and a sample came in that contained less than 50 picocuries of plutonium, the lab would mark a "U" on paper and report the amount as an undetectable -- a "nondetect," in cleanup lingo.
Although a layman hearing the word "nondetect" could easily think that meant a sample was uncontaminated, that might not be the case. The actual amount of the nondetect could be anywhere from 0 to 50 picocuries -- three times the EPA's safe-drinking-water standard. "The lab's not saying the concentration is zero if a 'U' is there," concedes Bollmann. "What it's saying is that it can't say with certainty the compound is present in any concentration."
Some of the wells contain results ranging from hundreds, to thousands, to a million picocuries or more for americium, arsenic, iodine and neptunium; these results are also recorded in the EPA's Record of Decision as the "maximum detected concentration." According to Hooten, however, the numbers do not reflect the actual radionuclide concentrations that exist at the site, but rather detection limits. "It was just a first run," she says. "I can't given you a specific reason for why those detection limits were chosen."
Or why they were set so high. According to Dan Hirsch, a California expert on nuclear-policy issues, the detection limits in the Lowry database are so high that, in many cases, they effectively mask any evidence of contamination. "If the data are reported correctly, the agencies are using detection limits that grossly exceed safe drinking-water levels," he says. "If this is indeed what they have done, it would be inappropriate from a health standpoint, because their monitoring techniques would be incapable of seeing contamination at the levels that these agencies say produce unacceptable health risks."
This practice of labeling high results as U's, or nondetects, extends to numerous other radionuclides and many of the non-radioactive compounds as well.
"I don't know the reason behind it," Hooten responds, when asked why the detection limits for the database were set so high. "It could have been the Lowry Coalition, CH2M Hill or Waste Management."
But according to Lori Tagawa of Waste Management, the lab sets the detection limits. "We don't tell them what the detection limit should be because we don't have any idea," she says.
As the federal regulatory agency overseeing Lowry, the EPA could have ordered its contractors to come up with results that would have showed the actual levels of contaminants present in the landfill. In an undated paper, Milt Lammering, the EPA's own radiation expert, notes that the detection limits at Lowry had been set so "unrealistically high" that it was impossible to know with certainty what the concentrations of plutonium and americium were in some wells.
Despite public opposition, landfill officials moved ahead with the project, and on the morning of July 25, 2000, Lowry groundwater began flowing through the sewers. A few hours later, a manhole on East Hampden Avenue blew its cover and spewed 1,880 gallons of contaminated water across the ground.
After fixing the manhole and reporting the incident to the EPA, Lowry officials turned the water back on. For three months, the clear-looking liquid whooshed through darkened sewers at a rate that was roughly equal to four garden hoses running at full strength.
Before leaving Lowry, the water was pumped into a small treatment facility, where it was passed through carbon filters and a tank filled with ultraviolet light. These processes are supposed to reduce volatile organic chemicals such as solvents, but they do nothing to remove the heavy metals, radionuclides, PCBs or pesticides still present in the water.
A round of sampling done just days before the discharge began showed 0.32 picocuries of americium present in the water. While that was a very small amount, it's still twice the state standard for groundwater and much higher than what you'd except to find in a normal background sample.
Other samples showed a total of 0.15 picocuries of plutonium-238 and -239 in the treated water. Again, it was a small amount -- but still higher than what you'd expect to find under normal conditions.
Lowry officials had hoped to pump a mix of water through the sewers: 70 percent from the northern portion of the site and 30 percent from a much more contaminated area near the center of the landfill called the "North Toe." But the North Toe water proved to be so contaminated that officials soon began debating whether they should reduce that portion of the mix to 5 percent.
On October 20, the discharge was again halted when a lab discovered that the water was toxic to a small organism called Ceriodaphnia dubia. These small crustaceans do what canaries do in underground mines: They alert scientists to potential problems that could later affect larger creatures, such as fish and humans.
For three months, officials from Metro, Denver and Waste Management tried to figure out what was wrong. Eventually they concluded that it was the test itself -- and not the water -- that was causing problems. On January 12 of this year, the flow resumed.