Modine MFG Co. - Camdenton

According to applicable state and federal hazardous waste laws and regulations, after a hazardous waste treatment, storage and disposal facility stops operating in an area on its property, that area goes through a closure period. During closure, the facility owners and operators remove and clean their equipment, structures and soil. All hazardous waste treatment, storage and disposal facilities are also required to investigate and clean up releases of hazardous waste to the environment at their facility resulting from present and past hazardous waste handling practices. Closure and corrective action investigations and remediation activities can occur at the same time.

Details regarding the removal and initial closure activities for the three hazardous waste container storage areas are unknown. In 1983, Sundstrand graded and paved the Area 1 hazardous waste container storage area, turning it into an employee parking lot. Area 3 was also removed to make room for a building expansion to the south. In 1985, Sundstrand removed mud pit #2, closed the Area 2 hazardous waste container storage area and installed a wastewater pretreatment system over the area.

In September 1990, before Modine purchased the site, Sundstrand submitted a closure plan to the department to officially close the hazardous waste container storage areas and release the facility from regulations as an interim status hazardous waste treatment, storage and disposal facility. In December 1990, Modine notified the department and the U.S. Environmental Protection Agency (EPA) of the ownership change. According to applicable state and federal hazardous waste laws and regulations, Modine, as the owner of the property at that time, was required to investigate and clean up releases of hazardous waste to the environment at the facility resulting from present and past hazardous waste handling practices, including releases by previous facility owners.

In 1991, Law Environmental Inc. performed an Environmental Site Assessment for the facility property, on behalf of Modine. The sample results showed low levels of volatile organic compounds along the west side of the manufacturing building, in the area of the former hazardous waste container storage areas 1 and 2. Modine submitted a revised closure plan for the hazardous waste container storage areas in March 1992. The department approved Modine’s closure plan, with modifications, in November 1992. The modifications required additional sampling.

During this same timeframe, Jacobs Engineering Group Inc. performed a visual site inspection and preliminary assessment of the facility, on behalf of EPA, due to a complaint claiming 4,500 gallons of TCE had been spilled at the facility. The assessment was conducted to identify and gather information on actual and potential releases of hazardous waste to the environment. The 1992 Environmental Priorities Initiative/Preliminary Assessment Report identified six solid waste management units recommended for additional investigation. These units included City Lagoon #3, mud pits, three container storage areas and monorail vapor degreaser and still.

In July 1993, Law Environmental Inc. closed the container storage areas and performed the required additional sampling to further assess the presence of TCE and related volatile organic compounds. On behalf of Modine, Law Environmental submitted a closure report to the department in September 1993. The sampling results showed detectable levels of volatile organic compounds and lead in the soil.

At the department’s request, Modine performed additional sampling and an environmental risk assessment for the former drum storage areas. This process involved gathering information and using risk factors to evaluate the risk posed to human health or the environment by actual or potential releases of specific hazardous wastes. On behalf of Modine, Law Engineering and Environmental Services submitted an Environmental Risk Assessment Report to the department and EPA in August 1994. The assessment determined the minimal amounts of volatile organic compounds in the soil did not pose a health risk and the lead levels in the soil was not considered a significant health risk. However, the department determined the assessment did not fulfill the closure requirements with regard to the groundwater contamination. The department required Modine to determine where the waste was located to non-detectable levels (horizontal and vertical extent of contamination).

In August 1995, Dames & Moore performed the required investigation, which also included a groundwater investigation. Additional groundwater monitoring wells were installed and sampled every three months. Samples taken during installation showed groundwater contamination was present. On behalf of Modine, Dames & Moore submitted a Findings of an Investigation Report to the department in February 1996. The sample results showed detectable levels of TCE and other related volatile organic compounds in and around the employee parking lot and along the buried wastewater discharge line along the west side of the manufacturing building. Additional investigation was determined to be needed. A Deed Notice, signed by the Camden County Recorder of Deeds on Sept. 23, 1996, was placed in the property chain-of-title to notify any potential buyers that the property had been used to manage hazardous wastes.

In November 1996, Dames & Moore performed a soil investigation at the former City Lagoon #3, to determine whether volatile organic compounds, particularly TCE, were present and whether the lagoon was the source of the TCE contamination in the groundwater. Because the untreated wastewater from the Modine property mixed with sanitary wastes from nearby residences in the sewer system on its way to City Lagoon #3, legal limitations were imposed on the department’s ability to use Resource Conservation and Recovery Act (RCRA) authority to investigate the groundwater contamination. The groundwater contamination issue was referred to the department's Environmental Remediation Program, Superfund Section, and is regulated under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). For information about the lagoon investigation, visit the department'sCity Lagoon #3webpage.

In April 1997, Dames & Moore performed a soil investigation under the manufacturing building floor, in the area of the monorail vapor degreaser and still and former hazardous waste container storage area 3. On behalf of Modine, Dames & Moore submitted a final report to the department in May 1997. The sample results showed TCE was detected in the soil east of the former above ground solvent storage tank location and north of the monorail vapor degreaser. Volatile organic compounds were also detected in the soil beneath the manufacturing building foundation, in the area of the former monorail vapor degreaser.

In September 1997, Dames & Moore performed a soil investigation at the mud pits determine if a release had occurred. The sample results showed TCE levels increasing as the samples went deeper into the ground. In October 1997, the soil surrounding mud pits #1, #3 and #4 and debris from the mud pits (i.e., cement lining, PVC piping and scrap metal) were removed. About 13 tons of soil were shipped off site for hazardous waste disposal and 184 tons were shipped off site for disposal as special waste. On behalf of Modine, Dames & Moore submitted a final report to the department in December 1997. The areas where volatile organic compounds were detected above the cleanup goals were limited and in areas difficult to get to for removal. Removing the soil would have potentially weakened the building foundation or damaged underground utilities, such as fire lines.

In January 1999, TCE was detected in the City of Camdenton's Mulberry Well, at levels above the maximum level allowed in drinking water, as established under the Safe Drinking Water Act. The Mulberry Well is a city municipal well, located about 600 feet southeast of the Modine property and 1000 feet south of City Lagoon #3. The Mulberry Well was disconnected from the city's water supply system and is no longer used for drinking water. Because groundwater contamination issues were referred to the department's Environmental Remediation Program, Superfund Section, the Mulberry Well was also referred for investigation and remediation. For information about the Mulberry Well investigation, visit the department'sMulberry Wellwebpage.

On Aug. 9, 1999, Modine voluntarily entered into a Corrective Action Abatement Order on Consent with the department, Order No. 99-HW-002. The Order required Modine to carry out a facility-wide investigation to fully determine where the soil contamination at the facility property is located (horizontal and vertical extent of contamination) and possible remedial alternatives for the contamination. The department’s Waste Management Program, Engineering Section is providing oversight of these activities. Both the Modine facility and City Lagoon #3 appear to be contributors to the TCE groundwater contamination. The Engineering and Superfund sections are closely coordinating all environmental investigation and cleanup activities, given the connection between the environmental issues.

In July 2000, as part of a plant renovation, Modine removed the wastewater discharge line that connected the mud pits to the city of Camdenton sewer system. Soil samples were collected along the base and walls of the 220-foot excavation trench. TCE was detected at one sample location; however, the level detected was far below screening levels for residential use. TCE was not detected in any other samples collected along the excavation trench.

In October 2000, CH2M Hill Inc. was contracted by Modine to perform a soil investigation west of the manufacturing building, near the end of a former stormwater drain line. An approximately 4,000 square foot area of the parking lot, in the area of the former hazardous waste container storage area 1, was identified as contaminated. Excavation activities began in October 2001, and included removing about 4,800 cubic yards of soil. As more information became available, the amount of contaminated soil was more than originally estimated, especially to the east and southeast of the known impacted area. Excavation activities stopped and additional investigations were performed to better understand the extent of contamination. In 2002, an additional 4,700 tons of soil were removed. Confirmation sample results showed all contaminated soil above site-specific cleanup levels was removed. The cleanup levels were developed to be protective of groundwater.

In March 2003, CH2M Hill performed an indoor air quality assessment for the manufacturing building, in order to help the department complete an Environmental Indicator determination. Environmental Indicator evaluations were developed by EPA to measure the progress in protecting human health and the environment at facilities performing environmental cleanups. These measures evaluate current environmental conditions and calculate whether people are currently being exposed to environmental contamination at unacceptable levels, and whether any existing plumes of contaminated groundwater are expanding, stable, shrinking or adversely affecting surface water bodies. The department was concerned residual volatile organic compound levels in the soil or water beneath the manufacturing building, or along the west side of the building, could be vaporizing and entering the air inside the building. The sample results showed low volatile organic compound levels in the indoor air, below site-specific screening levels and the lowest OSHA occupational exposure limit. The volatile organic compound levels were also used to calculate cumulative risks, which were determined to be acceptable for an operating facility.

In 2006, CH2M Hill performed a soil investigation under the manufacturing building, on behalf of Modine. Soil borings were advanced beneath the west wall of the manufacturing building, at former mud pits #1 and #3. A horizontal boring was advanced under the manufacturing building in the area of the former monorail vapor degreaser and still. In 2007, additional soil borings were taken through the manufacturing building floor, in the area of the former monorail vapor degreaser and still. The sample results showed volatile organic compound levels were below site-specific screening levels.

As required by the corrective action order and on behalf of Modine, CH2M Hill submitted a RCRA Facility Investigation Report to the department and EPA in April 2008. The report summarized the soil investigations and included both a Human Health and Ecological Risk Assessment. It also evaluated the indoor air against OSHA occupational exposure limits, which are for operating facilities and do not take into account the potential for vapors to enter from beneath the floor. The department determined additional indoor air investigations were necessary to determine if volatile organic compounds were vaporizing in the soil or water beneath the manufacturing building and entering the air inside the building. In August 2010, indoor and outdoor air samples were collected at the facility property. The highest TCE level detected was below the screening level based on EPA’s preliminary TCE toxicity values. In March 2012, Modine stopped operating and removed all equipment and machinery from the building.

Modine's earlier investigations focused on soil contamination at the site. Due to advances in science and the understanding of potential health effects associated with vapors released from soil and groundwater contaminated with volatile organic compounds, the focus shifted to investigating vapors inside the manufacturing building and nearby residential homes, known as vapor intrusion. In 2013, CH2M Hill submitted a Quality Assurance Project Plan to the department, on behalf of Modine, for indoor air and sub-slab soil gas sampling in the manufacturing building. The actual sampling was delayed due to technical difficulties with the building’s ventilation system and the property going into foreclosure. During this same time period, EPA released final TCE toxicity values, which resulted in lower screening levels than were used in the 2003 and 2010 indoor air sampling events.

In March 2015, CH2M Hill collected sub-slab soil gas samples beneath the manufacturing building in areas not previously sampled, air samples inside the manufacturing building and air samples just outside the manufacturing building. On behalf of Modine, CH2M Hill submitted a Vapor Intrusion Evaluation Summary Report to the department in June 2015. The sample results showed no TCE detected in the outdoor air sample collected upwind of the building; however, TCE was detected downwind of the building. TCE levels in the indoor air were above risk-based target levels for non-residential land use and above screening levels for industrial air. TCE levels in the sub-slab soil gas were extremely high, above screening levels for residential and commercial use. It was suspected these vapors were entering the manufacturing building and were the main source of the measured indoor air concentrations.

In July and August 2015, CH2M Hill performed outdoor soil gas sampling on the eastern and northern facility property lines, next to the nearby residential areas. On behalf of Modine, CH2M Hill submitted a Vapor Intrusion Evaluation Summary Report to the department in October 2015. The sample results showed the highest TCE levels in soil gas were above screening levels for residential and commercial use. The sampling location was at the eastern facility property line, about 10 feet west of a residential property and 80 feet south of an existing sanitary sewer line serving the nearby residences. TCE levels in soil gas near the sanitary sewer line on the northern side of the building were above screening levels for residential use. The sewer line runs east from the manufacturing building into a sewer tie-in drain, where it splits north to Sunset Drive and east to Mulberry Drive (the neighborhood to the east of the facility property). The sample results suggested the possibility of TCE vapors entering the sewer line, traveling to and entering the nearby homes and building up to levels of potential health concern.

Based on the outdoor soil gas sampling results, the department requested Modine to obtain access to and perform indoor air and either sub-slab or crawl space soil gas sampling at select homes north of the facility property on Sunset Drive, east of the facility property along Mulberry Drive and any other nearby homes connected to the sewer line. The department also requested Modine collect soil gas samples from the gravel subgrade along the sewer line along the length of Mulberry Drive and another round of soil gas samples from the previously sampled locations on the facility property.

Sewer gas samples were collected within the sewer lines in early December 2015. Soil gas samples were planned in the gravel subgrade along the sewer line, but were not collected until March 2016, due to heavy rain and water in the sampling ports. Sewer gas samples were also collected at seven locations within the sewer lines in March 2016. Sewer gas at two locations was detected at levels above health concerns.

CH2M Hill began the Residential Vapor Intrusion investigation in early December 2015. Indoor air and sub-slab or crawl space sampling were conducted at select residences four times per year, in order to evaluate the potential effects of temperature changes on vapor intrusion. Ten total residences were sampled, located north of the facility property on Sunset Drive and east of the facility property along Mulberry Drive. The sample results showed TCE levels were above the sub-slab soil gas screening level at one residence; therefore, a sub-slab mitigation system was installed. Based on the December/January sampling event results, the department requested Modine expand the residential sampling to include homes north of Sunset Drive, along Bent Tree Lane.

The March 2016 sampling event included the selected residences along Bent Tree Lane and the residences sampled in December 2015. The sample results showed TCE levels above the response action level at one residence on Mulberry Drive. Air-purifying units were installed at this home and permanent vapor mitigation measures were conducted in October 2018. Permanent mitigation measures included replacing the subfloor and tile in the bathroom, affixing the toilet with new wax seal and conducting indoor air samplingafter the repairs to confirm that migration pathways had been removed.

A total of 25 residences entered into the quarterly indoor air sampling program. Indoor air and either sub-slab or crawl space soil gas samples were collected at each residence where access for sampling had been granted. Residences that complete four indoor air and sub-slab or crawl space sampling events, with sample results showing TCE levels below the response action level, were removed from the quarterly sampling program. As of October 2019, all 25 residences completed the quarterly sampling program. The two residences with mitigation measures are in an annual inspection program to confirm that the mitigation measures continue to operate as intended.

CH2M Hill began the sitewide soil vapor investigation in September 2016. Phase I of the investigation included sampling soil vapor, soil and groundwater on the eastern and northern sides of the building, to further evaluate possible ways the volatile organic compounds could move from the facility towards the residential properties. CH2M Hill began Phase IIof the investigation in December 2017. Phase IIincluded installing 62 passive soil gas samplers throughout the manufacturing building. Passive soil gas samplers are made of an absorbent material that is placed in a hole drilled through the floor of the building. The samplers are left in the hole for several weeks before being removed and sent to a laboratory to be analyzed. The results of the passive soil gas sampling showed that the highest concentrations of vapors beneath the building are in the northern partof the building. This corresponds with the oldest part of the building and where the majority of the degreasing operations were located. CH2M Hill used the results of the passive soil gas sampling to identify locations for installing soil borings to collect soil samples from beneath the manufacturing building.

During May and June 2018, CH2M Hill drilled 15 soil borings and collected soil samples from beneath the manufacturing building. Bedrock beneath the manufacturing building made installing the borings difficult and CH2M Hill was unable to install all of the soil borings that were planned. CH2M Hill returned in October 2018, with a different drill rig and drilling method and installed an additional 28 soil borings. The soil sample results confirmed that the highest concentration of TCE in the soil under the manufacturing building was in the northern part of the building.

In October 2019, CH2M Hill, on behalf of Modine, submitted a revised RCRA Facility Investigation Report to the department and EPA, as required by the corrective action order. Additional revisions were submitted in June 2020. The report summarized the soil investigations under the manufacturing building and included a revised Human Health Risk Assessment. The department approved the revised report in August 2020.

Contamination remains in the subsurface soil under the manufacturing building. Contract excavation workers may be exposed to contaminated subsurface soils. The property is currently inactive, however facility workers are not likely to come into contact with soils beneath the building. The next step in the cleanup process is for Modine to perform aCorrective Measures Study to identify and evaluate possible remedial alternatives for the soil contamination.When the study is complete, the department and EPA will review the possible remedial measures and select the best remedy given site-specific considerations.