Updated Wednesday, May 22, 5:30 p.m.: The Department of Health & Senior Services is also posting its evaluations of the air monitoring data here. The regulatory standards that DHSS is using to estimate the health risks from landfill fumes are here.
Updated Wednesday, May 22, 9:15 a.m.: After two days of rain delays, work to remove six unused underground concrete pipes at the landfill began today.
On April 23, the Missouri Department of Natural Resources started twice daily measurements of hydrogen sulfide, benzene, and odor levels at points around the landfill. DNR has also been monitoring of reduced sulfur compounds (reported as hydrogen sulfide), sulfur dioxide, carbon monoxide, total volatile organic compounds (VOCs), and gamma radiation at three locations at the landfill.
Starting on May 20, DNR began posting the results to its website each day, along with a Missouri Department of Health & Senior Services summary of health risks. Some unhealthy levels of sulfur dioxide have been detected. Temporary (acute) exposure to sulfur dioxide can cause irritation of the eyes, nose, and throat, and can aggravate respiratory problems like asthma. However, according to the DHSS summary, "sulfur dioxide concentrations were not detected at levels predicted to cause more serious short-term or long-lasting effects."
Despite repeated requests, neither DNR nor DHSS has been willing to discuss the air monitoring results.
Updated Tuesday, May 21, 11:10 a.m.: Work at the Bridgeton Landfill has been postponed again due to the weather.
Mo. Attorney General Chris Koster and Bridgeton Police Chief Don Hood have confirmed that the police presence in neighborhoods near the landfill will be "substantially increased" during the construction period, in response to concerns over homes being unoccupied while residents are relocated to hotels. Residents who want to register their address and other information can call the Bridgeton Police Department at (314) 739-7557, or fill out an online form.
Updated 9:19 a.m.: Work will be postponed on this project due to weather conditions.
More work is scheduled to begin on Monday at the Bridgeton Landfill.
Crews will be removing six large underground concrete pipes that are no longer in use and have become unstable.
The pipes could be helping foul-smelling, potentially toxic gases to escape from the landfill, where an underground fire has been smoldering for two and half years.
Missouri Attorney General Chris Koster says residents can expect odors to get worse during the construction.
"The degree to which the odor may increase is both an unknown and a matter of disagreement among experts,” Koster said at a press conference last week. “Put simply, it could be a little, or it could be a lot. Some of it will depend on weather conditions.”
The Missouri Department of Natural Resources plans to step up air sampling at the landfill while the pipes are being excavated, including daily monitoring for hydrogen sulfide and benzene.
Koster says construction crews will be ready to respond if unhealthy levels are detected.
“There will be topsoil that is staged around the removal of the pipe that if air quality real-time monitoring were to detect concerning levels of any toxins, the work would immediately stop and topsoil would be pushed back into the holes,” Koster said.
Removal of the pipes could take until mid-June.
Follow Véronique LaCapra on Twitter: @KWMUScience