Boeing Co. Tract I Hazelwood

The McDonnell Douglas Corporation (McDonnell Douglas) closed the original cyanide and sulfide-bearing waste storage area in 1989. The department accepted the clean closure certification for this unit in November 1993.

In 1994, Science Applications International Corporation, on behalf of the EPA, performed a Resource Conservation and Recovery Act (RCRA) Facility Assessment for the site. The assessment was conducted to identify and gather information on actual and potential releases of hazardous waste and hazardous constituents to the environment. The 1995 RCRA Facility Assessment Report identified 32 solid waste management units that were recommended for additional investigation.

Four of the solid waste management units identified in the assessment required stabilizing interim measures. An interim measure is an action taken to temporarily control the contamination source or the path the contamination could take from the source to humans, animals or the environment, such as air, soil, water and food. The Boeing Company (Boeing) performed the following interim measures in October and November 1997:

• Cleaned and removed the waste oil tank in Building 5
• Cleaned the sumps and placed an asphalt lift over the paint booth satellite accumulation drum areas located outside the northwest side of Building 2
• Cleaned and sealed cracks in the concrete floor of the “less-than-90-day” storage area in Building 40
• Removed the leaking power transformer and impacted gravel and soil outside the northeast corner of Building 6

In response to the RCRA Facility Assessment, Boeing performed a RCRA Facility Investigation to define the horizontal and vertical extent of any contamination. The investigation was conducted in a phased approach, dividing the site into nine areas based on the results of the previous assessments, investigations, location of solid waste management units and interim measures. On behalf of Boeing, MACTEC Engineering and Consulting Incorporated submitted a RCRA Facility Investigation Report to the department and EPA in June 1998, with revisions in December 2004. The sample results showed soil and groundwater in Tract 1 contaminated with volatile organic compounds, polycyclic aromatic hydrocarbons, polychlorinated biphenyls (PCBs), metals and total petroleum hydrocarbons. The contamination is limited to the permitted facility. The contamination at the site also does not cross Banshee Road, which splits the site into northern and southern areas of contamination.

The RCRA Facility Assessment, RCRA Facility Investigation and later investigations identified the following potential sources of contaminant release: 68 underground storage tanks, three fuel distillation sites, a power plant, the industrial wastewater treatment plant, 32 solid waste management units and multiple drum storage areas. It was determined that 44 groundwater monitoring wells would be sampled twice a year until a long-term groundwater monitoring plan was put into place.

While conducting the facility assessment and investigation, McDonnell Douglas, and later Boeing, closed the remaining hazardous waste storage units at the facility. Boeing closed both the scrap dock shelter and new cyanide and sulfide-bearing waste storage area in 2001. The new cyanide and sulfide-bearing waste storage area was “clean closed.” Groundwater samples collected during the closure of the scrap dock shelter showed contamination above screening levels; however, it was determined the contaminated groundwater was from a nearby area of concern. The department accepted closure certifications for both units in November 2001, with the provision that institutional controls prohibiting groundwater use be put into place for the scrap dock shelter, as part of the final remedy. The department accepted closure certifications for most of the other units in 1993, 1995, 2001 and 2003. The remaining units are being addressed under corrective action.

At the department’s request, Boeing performed a risk assessment of the contaminated areas to determine if they exceeded risk levels and to address remaining elements necessary to adequately characterize the site. The risk assessment subdivided the nine areas of the site into 23 subareas, each characterized by similarities in factors that affect human health under current and reasonable future land use conditions. The risk assessment generally followed the Missouri Risk-Based Corrective Action (MRBCA) process. On behalf of Boeing, the RAM Group submitted a Risk Based Corrective Action Report to the department and EPA in September 2004, with revisions in 2009. The report concluded the cumulative risks were below the department and EPA target risk levels for 14 out of the 23 sub-areas. In the nine sub-areas that exceeded cumulative risks, the exceedances were for non-residential workers and construction workers. Of the nine subareas, five were determined to need interim measures implemented. Contaminated soils were removed from the five subareas in May and June 2006, which included the perchloroethylene (PCE) transfer area outside Building 51, former jet fuel underground storage tank farm immediately west of Building 41, 1000-gallon diesel underground storage tank next to Building 2, trash contactor located at the northwest corner of Building 220 and scrap metal recycling dock. Interim measures included removing the impacted soil and transporting it to a permitted hazardous waste disposal facility. The excavated areas were then backfilled with gravel.

As part of the EPA’s independent review of the Risk Assessment Report, the EPA asked Tetra Tech to perform a risk assessment of selected areas using the EPA Risk Assessment Guidance for Superfund (RAGS) process. The intent was to compare the results obtained from the MRBCA and RAGS risk assessment approaches. Tetra Tech submitted a Risk Assessment Report to the department and EPA in March 2008. The report concluded that the two risk assessment approaches generally resulted in similar risk management decisions. The Tetra Tech report identified two additional subareas that exceeded risk levels.

At the department’s request, Boeing performed a Corrective Measures Study to identify and evaluate possible remedial alternatives for the remaining soil and groundwater contamination. On behalf of Boeing, the RAM Group submitted the final Corrective Measures Study Report to the department and EPA in February 2012, with revisions in November 2012, July 2013, and July 2014. The report included Boeing’s preferred final remedy along with other remedial alternatives. The department selected the best remedy from the Corrective Measures Study Report, given site-specific considerations for each solid waste management unit and area of concern. The department prepared a Statement of Basis that summarizes the remedial alternatives and the department’s basis of support for the proposed final remedy. The department incorporated the proposed final remedy into Boeing’s draft hazardous waste permit during the permit renewal. The public was invited to review and comment on the proposed remedy and draft permit during a 45-day public comment period. On Nov. 15, 2017, the department, in coordination with EPA, approved the proposed final remedy and issued the final permit. The approved final remedy included property activity and use limitations in the form of enforceable environmental covenants. These covenants are clauses listed in the chain-of-title for the affected properties, which notifies in perpetuity, any potential purchaser of the environmental conditions of the properties. The environmental covenants were recorded in 2018 for Boeing and GKN. The Airport’s covenant was recorded in 2020.

Starting in 2023, Boeing began investigating and addressing previously unknown hexavalent chromium releases to soil and groundwater from the industrial sewer lines throughout the facility which receives wastewater from Boeing facilities at and near the facility. Interim measures have been implemented on a portion of the industrial sewer line to treat the contamination in place the potential of contaminated groundwater. The section of industrial sewer has been repaired and no longer releases to the environment.
Currently, with the approved groundwater monitoring program and the approved sampling and analysis plan, 34 monitoring wells are sampled annually and 17 are sampled once every three years.