The Camdenton treatment plant lagoon before it was closed.

Between 1961 and 1989, wastewater from the 221 Sunset Drive manufacturing facility discharged to City Lagoon #3. The wastewater contained trichloroethylene (TCE), also referred to as trichloroethene, which resulted in subsurface contamination in the lagoon and surrounding area.

Between December 1989, when City Lagoon #3 was closed, and June 1989, when the city’s wastewater treatment plant was brought online, wastewater from the manufacturing facility was discharged to the Camdenton Treatment Plant Lagoon, also known as the C.P. White Lagoon. This lagoon is located on Ha Ha Tonka Road, about 1.3 miles southwest of City Lagoon #3.

The city closed the Camdenton Treatment Plant Lagoon in June 1989, when the city’s wastewater treatment plant became active. The wastewater treatment plant was built over a portion of the former Camdenton Treatment Plant Lagoon. The Camdenton Industrial TCE Contamination Advisory Team (CITCAT) identified this lagoon as a potential TCE contamination site, and requested the department conduct an investigation.

Investigations

Following the Superfund site investigation process, the department completed a pre-CERCLA site screening and a site investigation, documenting the potential release of TCE into the environment. For information about how to read and interpret the data, visit the department's Understanding Data webpage.

Pre-CERCLA Site Screening

The department began the pre-CERCLA site screening on Feb. 1, 2018. Information gathered through former employee interviews, discussions with CITCAT members and a review of city records indicated there was a potential for a release of TCE from the 221 Sunset Drive manufacturing facility to the Camdenton Treatment Plant Lagoon site, during the 18-month period in the late 1980s. During this time, the manufacturing facility had a newly installed wastewater pre-treatment system in place. According to a former employee who worked at the facility during this period, the floor drains throughout the facility connected to the wastewater pre-treatment system. TCE drippage from degreased parts onto the manufacturing facility floor was common. In sufficient volume, this waste TCE could have found its way to the floor drains. The facility's wastewater pre-treatment system was designed mainly to review metals and would not likely have had a significant effect on TCE levels in the wastewater. Between April and June 1986, Sundstrand, the owner of the manufacturing facility at that time, sampled the pre-treatment system liquid waste. In 12 samples collected, TCE levels ranged from non-detect to 2,230 ug/L or parts per billion (ppb). Based on this information, it is possible that TCE was released to the Camdenton Treatment Plant Lagoon site over the 18-month period in the late-1980s.

Site Inspection

Based on the pre-CERCLA site screening findings, the department began a site inspection investigation on Aug. 18, 2018, to further assess the potential release. The department conducted two separate sampling events, one on Dec. 19, 2018, and another on April 17, 2019. The two potential exposure pathways of concern identified for the investigation were vapor intrusion and groundwater used as drinking water. Seventeen private wells near the Camdenton Treatment Plant Lagoon site were previously sampled as part of the investigation for the nearby Dawson Metal Products Camdenton Facility #2 site. No TCE was detected in any of the wells, which indicated that if TCE was released at the Dawson or Camdenton Treatment Plant Lagoon sites, it was not significant enough to pose a threat to drinking water sources.

Shallow groundwater was sampled from within the footprint of the former Camdenton Treatment Plant Lagoon site during both site investigation sampling events. One sample was taken at about 20 feet below ground surface (bgs) near the treatment plant office building. Five samples were taken between 8 and 17 feet bgs at locations within the site's bermed cell, located just north of the office building. No TCE was detected in any of the shallow groundwater samples. During the December 2018 sampling event, soil cores were collected from the surface to 20 feet bgs at a location near the treatment plant office. No volatile organic compounds, including TCE, were detected. Eight soil gas samples were also collected from different depths at locations next to the treatment plant office. No TCE was detected in any of these samples. Based on the sample results from the department’s investigations, no TCE release was documented at the Camdenton Treatment Plant Lagoon site.

Conclusions

The department performed an investigation at the Camdenton Treatment Plant Lagoon site, which was completed in 2019.  No TCE was detected in any of the private wells near the site. No TCE was detected in any of the shallow groundwater samples taken within the footprint of the former Camdenton Treatment Plant Lagoon site. No volatile organic compounds, including TCE, were detected in the soil or soil gas samples at the site. Based on this finding, the department has concluded there was not a significant release of TCE at the former lagoon.  No further investigation is planned for the site.