West Lake CAG NRRB Submission REVISED ADDENDUM January 4 2018

11) Short and Long-Term Seismic Risk
Evaluation of earthquake risks at the West Lake Landfill appears deficient. The CAG is greatly
concerned about the unlined landfill being in the alluvial floodplain of the Missouri River. The
landfill is susceptible to liquefaction in the event of a large earthquake. Using the Modified Mercalli
Intensity Scale applied to a 7.6 magnitude earthquake along the New Madrid Fault, St. Louis
County would experience, “Panel walls thrown out of frames; fall of walls, monuments, chimneys;
sand and mud ejected; drivers of autos disturbed. 12 ” It’s not clear to the CAG how any cap-andleave
design will prevent the ejection of sand, mud, radioactive and non-radioactive contaminants of
concern at the landfill. Further, the liquefaction of the alluvium will cause slumping and
mobilization of the radioactive contamination into the groundwater, which will make it significantly
more difficult and expensive to remove in the future.
The DNR estimates the probability of a repeat of the 1811-1812 (magnitude 7.5-8.0) earthquakes is
7-10%. More from the DNR:
“The NMSZ [New Madrid Seismic Zone] appears to be about 30 years overdue for a
magnitude 6.3 quake because the last quake of this size occurred 100 hundred years ago at
Charleston, Missouri; on Oct. 31, 1895 (it was a magnitude 6.7). A magnitude 6.3 quake
near Lepanto, Arkansas, on Jan. 5, 1843, was the next prior earthquake of this magnitude.
About 75 percent of the estimated recurrence time for a magnitude 7.6 earthquake has
elapsed since the last quake of this size occurred in 1812. 13 ”
Further, in 2014 the United States Geological Survey (USGS) and various universities discovered a
new seismically active zone closer to the West Lake Landfill, called the St. Genevieve Seismic
Zone. The severity of impacts in the St. Louis region from a 7.6 magnitude earthquake that
originates in St. Genevieve would likely be greater than a 7.6 magnitude earthquake that originates
near the New Madrid fault.
From the Indiana University report’s author Michael Hamburger “It’s an underappreciated zone of
seismic activity that has potential implications for St. Louis and other populated areas in eastern
Missouri and Southwestern Illinois,” he said. “It’s comparable to the Wabash Valley Seismic Zone
in western Indiana, which is capable of producing moderate-sized earthquakes every few decades
and perhaps has the potential for larger earthquakes. 14 ”
12) Air Contaminates
Exposure pathways focus on the inhalation of air or ingestion of soils from the landfill. The risk of
inhalation from air should include smoke that can carry radionuclides as well as toxic particles and
gases considering that several surface fires have occurred at the landfill since the radioactive wastes
were dumped. Reported fires that the CAG is aware of include the following:
− 2015: Surface fire in grass area near OU-1 Area 1
− 2013: South quarry surface fire along Old Boenker Rd.
12
Facts About the New Madrid Seismic Zone, Missouri Department of Natural Resources. Accessed Nov. 2017.
https://dnr.mo.gov/geology/geosrv/geores/techbulletin1.htm
13
Facts About the New Madrid Seismic Zone, Missouri Department of Natural Resources. Accessed Nov. 2017.
https://dnr.mo.gov/geology/geosrv/geores/techbulletin1.htm
14
IU Geologists Identify New Seismic Zone Near Illinois-Missouri Border, Indiana University. Accessed Oct. 2017:
http://archive.news.indiana.edu/releases/iu/2014/11/ste-geneview-seismic-zone.shtml
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