Croda produces surfactants – short for surface-acting agents – which are used by other manufacturers to make a variety of consumer products, as well as processed into ethylene glycol, an ingredient in plastic polymers and antifreeze, at the Atlas Point plant off of Route 9 near New Castle. An industrial plant has operated at that location since 1937. Croda uses the chemical ethylene oxide as a material in producing its products. Prior to 2018, Croda imported ethylene oxide from other locations in rail cars, and offloaded it at the plant. Then Croda built the new ethylene oxide plant at the facility, to produce its own ethylene oxide. This is referred to as the ethylene oxide plant. The older portion of the plant that uses the ethylene oxide to produce Croda’s final products is referred to as the legacy plant or the batch plant.
On September 17, 2020, DNREC staff was onsite at Croda’s facility for a “stack test,” which is testing of the emissions release at the ethylene oxide plant. In the ethylene oxide plant, emissions from the processing and from the filling of storage tanks are either captured for reuse in process or are vented to the air via a “stack,” which is like a large chimney. Testing was being conducted at the “hotwell” (which is part of the wastewater discharge from the ethylene oxide plant) and the “scrubber” on the stack (which controls emissions from the ethylene oxide storage tanks as the tanks are filled). The testing was stopped midway through due to concerns about the results being observed at the hotwell. The ethylene oxide plant was shut down on September 17 and has not yet resumed operation. Croda provided results of the testing and other information to DNREC on October 6. The results showed the scrubber was not working as expected, and that there was ethylene oxide present at the hotwell, which would not have been present if the process was working as permitted. Some aspects of the system were not evaluated in the September stack test because the test was ended early. Investigation found that that there was a source of emissions connected to the scrubber that was not included in the permit application. This caused a reduction in the amount of pollutants being removed from the air emission, which caused the total permitted emissions at the scrubber to be exceeded. Both the undocumented connection, and the reduced scrubber efficiency were violations of the air permit for the ethylene oxide plant. Over the following weeks, DNREC staff requested additional information from Croda and completed calculations of the emissions to get an idea of how much ethylene oxide had been emitted over the prior months beyond what was allowed in its permit. The result of this work is the notice of violation that was issued November 11, 2020 for connecting and routing an unpermitted source into the scrubber; exceeding the annual emission limit for ethylene oxide at the scrubber; failure to meet the volatile organic compound (VOC) removal efficiency at the scrubber; and operation of an unpermitted source of ethylene oxide at the hotwell. The legacy portion of the Croda plant has continued operating, with ethylene oxide brought in from other sources. The NOV issued on November 11, 2020 can be found at www.dnrec.delaware.gov/Admin/Documents/croda-nov-20201111.pdf.
In November 2018, there was an accidental and uncontrolled released of ethylene oxide from the ethylene oxide plant that caused concern for the public safety of those in the area. The uncontrolled release was due to a failed gasket. The recent violation was issued because an air pollution control device, the scrubber, failed to meet the required removal efficiency, and allowed more emissions over the course of about 9 months. The current violation was an exceedance of the permitted emission level, but not a public safety issue.
DNREC and Croda officials realized during the September testing that the hotwell was not operating as expected due to the presence of ethylene oxide. The testing was stopped and the plant went into a shutdown, which the company is now using for maintenance. To date, operation has not resumed, so the emission violation is not ongoing. DNREC requested information from the company and used that information to calculate if emission limits for the year had been exceeded. Based on the calculation that emissions limits had been exceeded, the notice of violation was issued and the November 19 information session for the community was scheduled. DNREC takes seriously our enforcement responsibilities. The time it takes for a notice of violation to be issued is the time required to complete our investigation and ensure that the information in accurate.
The notice of violation is the beginning of an administrative process that could lead to a further enforcement action. DNREC staff will continue to gather information on the violation and the Secretary will determine what additional steps are necessary.
In the past 10 years, Croda has received two additional Notices of Violation from the Division of Air Quality besides the Thanksgiving 2018 incident and the most recent one. In 2014, the company was issued a violation for failing to submit an air permit renewal application on time. In January 2015, a stack test for a landfill gas-fueled generator found non-methane hydrocarbons being emitted beyond the permitted limit. The company made adjustments to the operation and passed the stack test three days later, but an NOV was issued for the failed test.
DNREC has urged and Croda has worked over the last several years to reduce ethylene oxide emissions at the legacy plant – from 1.35 tons in 2014, down to 1.16 tons in 2017, 1.10 in 2018 and 0.65 in 2019. The Croda plant is permitted for 20 tons of total volatile organic compounds, which includes a number of different air pollutants, and no more than 10 tons of any of the individual hazardous air pollutants Over the past few years, the Department has issued permits for the units in the legacy plant to install emissions control devices, which has reduced that facility’s ethylene oxide emissions. The legacy facility was expected to emit approximately 0.6 tons of ethylene oxide in 2020 and future years, due to a $15 million project to reduce emissions in the legacy portion of plant. The addition of the ethylene oxide plant to Croda has added back some of the emissions reduced in the legacy portion of the plant. With the emissions for which Croda has received a violation notice, the 2020 emissions will be around 1.8 tons of ethylene oxide. If the two parts of the plant – legacy and ethylene oxide – only emitted what they were allowed under their permits, the emissions would be approximately 0.89 tons of ethylene oxide. The Department is working on a plant-wide air permit renewal (called a Title V permit) for the facility which will incorporate ethylene oxide specific limits to reflect the ethylene oxide reductions achieved in the legacy facility.
Employees at the legacy plant wear personal EO monitors that alarm at 10 parts per million of ethylene oxide, ppm, but can read levels down to 1 part per million, which is the worker exposure recommendation from the Occupational Safety and Health Administration. There are also alarms for ethylene oxide installed throughout the legacy and ethylene oxide plants. There are local alarms that are activated at 5 parts per million within the grounds of the ethylene oxide plant. In addition to the EO alarms, there are LEL (lower explosive limit) sensors. The LEL sensors alarm at 0.3% EO (which is 10% of the LEL). The LEL and EO monitors in the EO plant did not alarm in 2020 because those levels were not reached within the plant area.
The Department is working with EPA to identify options for a continuous emissions monitoring systems (CEMS) to monitor the emissions from the scrubber stack in real time. Pending the outcome of that research, the Department may require further steps by the company for emissions monitoring.
The U.S Environmental Protection Agency revised its risk assessment of ethylene oxide in December 2016, determining that it was 50 times more potent than previously thought, and posed a cancer risk to humans when inhaled at specified levels. The EPA factored this risk level into calculations for plants around the country that emit ethylene oxide as a part of the 2014 National Air Toxics Assessment (NATA), which was released in 2017. At Croda, it should be noted that the emissions from the ethylene oxide plant are from a stack – basically a chimney – 110 feet in the air. This allows the emissions to disperse in the air more than a lower stack would. The reason stacks are used is so emissions disperse into the atmosphere well above the ground in order to prevent effects to people at the levels on which the EPA based its calculation. Based on available data, the EPA does not expect ethylene oxide levels in the air around facilities to be high enough to cause immediate health effects.
This is a critical question but also a hard one to answer. The known health risk from ethylene oxide is based on chronic exposure — exposure that takes place over a lifetime — inhaling at a sustained level of 20 parts per billion. The EPA’s calculations for the Croda plant – based on the revised health risk – is that there is a cancer risk of 110 in a 1,000,000 associated with ethylene oxide in the census tract to the north of the facility. This census track is modeled to have the highest risk in the area. That is based on Croda emissions level from 2014. (Please note that due to Delaware’s total population being less than 1,000,000, the Delaware Division of Public Health would report this metric as 11 in 100,000.) That is 0.01 percent. The other census tracts around the facility have risk associated with ethylene oxide that ranges from about 25 to 50 in 1,000,000.
At the virtual meeting on November 19, 2020, there was a question about the half-life of ethylene oxide. Half-life is the time it takes for the concentration of a chemical to be reduced by half, so it is a measure of how fast the chemical will react in the natural environment. Ethylene oxide is considered a volatile organic compound (VOC). Chemicals with this classification react in sunlight to generate ozone in the natural environment. Per EPA, the half-life of ethylene oxide is 69 to 149 days. After ethylene oxide is emitted, it dilutes and reacts in the natural environment. It’s important to remember that air mixing is constantly taking place in the atmosphere. Dilution and passage of time both act to reduce the concentration. The emissions from a facility, or any other source (such as a vehicle) do not stay in one place. They mix in the atmosphere and disperse away from the point or origin due to weather patterns. More information from the EPA about ethylene oxide can be found at www.epa.gov/sites/production/files/2016-09/documents/ethylene-oxide.pdf.
The ethylene oxide plant must prove that it can operate with emissions at or under the permitted levels before it can resume operations. For the purpose of testing only, DNREC will need to allow the ethylene oxide plant to start up, as authorized by the notice of violation, to complete stack testing of the emission sources at the ethylene oxide plant. The stack test is needed in order to determine whether the plant can operate with the lower level of emissions that is required and that it was not meeting earlier in 2020. Operation for the purpose of the testing will not include the hotwell or use of the unpermitted emission source connected to the scrubber. Plans for the stack test have been reviewed by DNREC and the EPA. The ethylene oxide plant will shut down following the completion of the testing. DNREC will then consider the path forward as Croda has requested to resume operations at the ethylene oxide plant. DNREC will consider that request based on proof of compliance and safe operation of the plant from the stack test.
As mentioned, the ethylene oxide plant will need to be started and brought up to full operation over a period of days before it is operating at a normal level where the stack test can be conducted. During the operation, the company must monitor water circulation and pressure through the scrubber. The tanks will be monitored for pressure and temperature also. These operational parameters will be reported to DNREC. During the test, DNREC staff will be on site and ethylene oxide levels and scrubber performance will be known in real time. The operational data will also be collected by DNREC staff for review.
This permit application remains an open matter, awaiting a hearing officer’s report and a technical memo that respond to and incorporate public comment from the July hearing. Work on this permit application has been on hold as the compliance issues have taken precedence, but it is currently pending for an eventual decision by the Department.