A Footnote Worth Noting

Stormwater runoff from West Lake Landfill, April 30, 2017. (Photo by Robbin Ellison Dailey)

Factoring in punctuation marks and MDNR’s double-talk changes the equation of the latest findings at the radioactively-contaminated West Lake Landfill site. 

In many ways, the test results released by the Missouri Department of Natural Resources last month are as unclear as the turbid stormwater the agency collected from the drainage ditches outside the perimeter the West Lake Landfill Superfund Site earlier this year.

Equally perplexing is the press release that accompanies the findings, which concludes that radioactive materials present in the sampling are not even from the West Lake Landfill. Moreover, the analysis is an of interpretation of data that itself is admittedly flawed, according to a footnote that explains two asterisks that appear in the listed test results.

The MDNR collected the stormwater samples on April 30 following heavy spring rains and then sent them to a contracted laboratory for testing. The press release does not reveal the name of the laboratory. The lab measured the samples for gross alpha and beta particles, along with total uranium and combined radium content, according to the MDNR. The analysis then compared the findings to stringent Missouri drinking water standards, concluding that radioactivity in the stormwater runoff was within permissible limits with one exception:  Gross alpha amounts exceeded the benchmark level and could not be fully attributed to either radium or uranium.

The samples were then tested for thorium, which is when the analysis appeared to have gone sideways. According to the MDNR: “The results do not indicate that the radionuclides in the sample are radiologically impacted material from West Lake Landfill.” If the thorium in the stormwater runoff from the landfill didn’t come from the landfill — where did it originate?

The MDNR attributes this anomaly to “the relatively low activity level of West Lake Landfill related radionuclides in the sample.”  The agency adds that Thorium-230 activity levels are similar to other thorium isotopes and that the waste from the landfill would be expected to have higher relative Thorium-230 levels.

If community members are confused by this explanation, it’s because the MDNR’s choice of  words and its explanation of the numbers are both as clear as mud.

The list of test results show that separate samples taken on April 30 found Thorium-230 in the landfill runoff at more than two pico curies per liter, but those findings both have asterisks behind each number. At the bottom of the chart, the presence of the asterisks are explained as follows: “Due to smaller aliquot volume, Thorium-229 laboratory tracer likely interfered with the result, causing it to be biased higher than actual Thorium activity by an approximated amount of 1.36 pCi/l [pico curies per liter].” 

 

In other words, the MDNR is attributing the elevated Thorium-230 to a laboratory error or miscalculation, and slashing the estimated amount by more than half.   The key phrases in this terse explanation are “likely interfered with” and “approximate amount.” Neither term sounds remotely scientific.

There is only one certainty in the MDNR’s test results: Radionuclides above background levels have migrated off the Superfund site and into the roadside ditches outside the West Lake Landfill on St. Charles Rock Road.

The MDNR’s conclusion: Further monitoring of the stormwater is recommended.

 

 

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