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EPA in Missouri

LaJolla Spring Cave Complex - Meramec Caverns


As of August 5, 2016, data analysis of air sampling in the back portion of the La Jolla Spring Cave Complex at Meramec Caverns indicated that levels of trichloroethylene (TCE) vapors were below levels of health concern. As a result, as of August 6, 2016, all portions of the caverns that are utilized for tours have been reopened to the public.

The front portion of the cave complex was reopened on June 10, 2016, following data analysis that indicated levels of TCE vapors in that portion of the caverns were below levels of health concern.

EPA will continue to monitor air sampling results for a period of four weeks to verify that TCE concentrations remain below levels of health concern for all areas now open for tours. After four weeks, if levels remain low, EPA will reassess any requirements for future air monitoring.

Controls ImplementedMeramec Caverns Map

Since March 24, 2016, the Potentially Responsible Parties (TRW Automotive U.S., LLC) have worked to address levels of trichloroethylene (TCE) vapor concentrations within the LaJolla Spring Cave Complex at Meramec Caverns. In part, this work included:

  • Installation of a set of air lock doors separating the upper level of the caverns from the lower level of the caverns
  • Installation of air scrubbers in the upper level of the cave including the gift shop/cafeteria
  • Installation of two ventilation shafts to increase airflow in the lower level of the cave, while also redirecting the natural airflow away from the air lock door system

As a result of this work, the three most recent sample results indicate that levels of TCE vapors are now below levels of health concern in the upper level of the cave. EPA will continue to monitor air testing results to verify that TCE concentrations remain below this level. Test results can be found by visiting the Oak Grove Village Well Superfund Site Document Collection.

Ongoing Monitoring

EPA is requiring the Potentially Responsible Parties (TRW Automotive U.S., LLC) to perform an additional four weeks of air monitoring to verify that TCE vapor concentrations remain below levels of health concern. At the conclusion of those tests, EPA will then evaluate and determine the frequency of future testing.

If, at any time, testing indicates that TCE vapor concentrations are not being sustained below levels of health concern, EPA will recommend re-closure, if necessary, to protect human health.

Mitigation activities are ongoing in the lower level of the caverns, where TCE vapor concentrations are higher due to direct contact with TCE in the water. Monitoring will continue in these areas to determine if acceptable TCE concentrations can be reached and sustained, which would allow the lower level of the caverns to be reopened for tours as well.  

UPDATE: As of April 1, 2016, recent testing results indicate TCE vapor levels in the gift shop/cafeteria have been reduced as a result of air scrubbers being activated in those locations. The gift shop/cafeteria have been closed since March 24, 2016.

At this time, EPA has advised the cave owner that levels are acceptable to reopen at this specific location. EPA will continue testing the air in the gift shop/cafeteria, and will recommend closure of those areas if necessary to protect public health. The cave remains closed for tours.

EPA Region 7 is directing the Potentially Responsible Parties at a groundwater contamination Superfund site in Franklin County, Mo., to perform additional work to protect workers and visitors from potentially harmful exposures to trichloroethylene (TCE) vapors in the nearby Meramec Caverns, a privately-owned tourist attraction near Stanton, Mo.

As a precautionary step, Meramec Caverns, also known as the LaJolla Springs Cave Complex, recently decided to cease cave tours while the Potentially Responsible Parties (TRW Automotive U.S., LLC) instituted controls to reduce TCE levels.


TCE vapors detected in the cave likely originate from two sources, the former TRW/Ramsey Facility in downtown Sullivan and the Sullivan Landfill. Both of these facilities are associated with the Oak Grove Village Well Superfund Site, which became part of EPA’s National Priorities List (NPL) in 2002. The former TRW/Ramsey Facility is managed by the Missouri Department of Natural Resources’ (MDNR’s) Resource Conservation and Recovery Act (RCRA) Program.

TCE contamination in the area’s groundwater has been under investigation since 1986, when it was first detected by MDNR during routine sampling of a well. From October 2002 to January 2005, EPA and MDNR sampled air in Meramec Caverns. In 2003, samples showed TCE concentrations above levels of health concern. The cave owner took immediate steps to increase air flow within the cave, and samples collected in 2004 and 2005 showed those actions had decreased TCE concentrations to acceptable levels.

In 2011, EPA issued a toxicological evaluation for TCE based on the best available science. This comprehensive evaluation, which underwent extensive external peer review, identified potential adverse health effects at lower concentrations of TCE than used in the past. The health effects that may occur following exposure to the lowest concentrations of TCE include heart malformations in the fetus and adverse effects on the immune system.

EPA, MDNR, the federal Agency for Toxic Substances and Disease Registry (ATSDR), and the Missouri Department of Health and Senior Services (MDHSS) met with the cave owner in December 2014 to discuss a MDHSS health consultation released Dec. 12, 2014, regarding TCE air concentrations in the cave air. The health consultation recommendations included the following: 1) inform workers of elevated TCE concentrations in the cave air, and potential health risks associated with TCE inhalation, and 2) implement permanent measures to mitigate vapor intrusion into the cave as soon as possible.

Since December 2014, EPA has overseen the implementation of a number of actions intended to address the TCE levels in the cave. While these actions have shown some merit, they have not demonstrated the ability to achieve and sustain TCE levels below levels of health concern. EPA continued to conduct air sampling in the cave throughout 2015.

In February 2016, based on new data from late 2015, ATSDR recommended to EPA that TCE exposures to employees in Meramec Caverns be stopped until they are brought below levels of health concern.

Since then, EPA has met with the cave owner and multiple partner agencies, including MDHSS, MDNR and ATSDR, to determine appropriate health-based benchmarks and specific actions that could be taken to protect the health of the cave’s workers and visitors. In March 2016, the owner of Meramec Caverns proactively closed the cave for tours while controls were being installed.

Oak Grove Village Well Superfund Site Document Collection

Oak Grove Village Well Superfund Site Administrative Record

More information, including research to date and letters exchanged by the participating entities, is included on this page. For additional information, please contact Tonya Howell at 913-551-7589 or at For media inquiries, please contact Angela Brees at 913-551-7940 or

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  • EPA Letter to OSHA (PDF)(2 pp, 295 K, 2/24/2016)
    EPA letter to Mr. David Keim outlining trichloroethylene contamination inside Meramec Caverns.