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Accident at a waste recycling plant in Järvenpää caused by a dangerous reaction

Publication date 9.2.2023 8.40 | Published in English on 10.2.2023 at 14.29
Press release

The Finnish Safety and Chemicals Agency (Tukes) has investigated an accident that took place at a waste processing and recycling plant in Järvenpää on 19 September 2022 in which the spread of a toxic gas generated in a dangerous reaction caused the death of an employee. During the investigation, significant deficiencies were discovered in the assessment of and preparation for risks in processing equipment. In addition to the investigated company, the investigation team proposes general recommendations to improve safety at waste processing plants and hazardous chemical plants that transport waste chemicals for disposal. The accident investigation report is now available on the Tukes website.

The chain of events leading to the accident started when an attempt was made to remove a precipitate adhered to a reactor vessel using mixed acid waste containing hydrogen fluoride and nitric acid.  The reaction between the precipitate and mixed acid waste generated toxic gases that spread from the reactor vessel to the process facility through an open sampling connection.   Two employees were exposed to the gases, resulting in the death of one of the employees.

The liquid metal salt solutions and neutralising acid and alkali waste handled in the plant’s production process had repeatedly formed a hard-to-dissolve precipitate which got stuck in reactor vessels. Attempts had been made to affect to the sticking by carrying out various process modifications and cleaning measures. No specific procedure had been established and no instructions were in place for the removal of the precipitate. Employees started to remove the precipitate without any pre-planning using mixed acid waste handled in the same process which resulted in a dangerous reaction. The employees were exposed to gas when they attempted to stop the dangerous reaction. 

The investigation team identified that the following factors had a particular impact on the accident: 

  • The hazards of mixed acid waste were not sufficiently understood in the company, and conflicting information about them was available.
  • Risks associated with the process had not been assessed sufficiently. The significance of risk control measures was not sufficiently understood, and they were not followed at the time of the accident.
  • No instructions or closely defined procedure were available for the removal of the precipitate.
  • The root causes of previous incidents taken place in the process had not been identified sufficiently.
  • The process did not include any measurements, alarms or other automatic protection measures that would have alerted employees of hazards or reduced the risk of human error.
  • The impact of the technical modifications made or the need to change working instructions had not been assessed.
  • Stopping the extensive gas leak in the situation by following pre-defined and trained operating models was too dangerous for employees. 

Recommendations for preventing similar accidents

To avoid similar accidents, it is essential that the hazardous properties of waste chemicals are identified in as much detail as possible. The best way is to identify the classification of waste chemicals in accordance with the CLP regulation*. In addition, it must be ensured, through the exchange of information between waste producers and handlers, that all parties have a similar understanding of the hazards and other properties of chemicals. 

Waste producers must ensure that the waste processing plant’s official permits address the hazardous properties of waste chemicals, meaning that the plant is permitted to process the waste in question. The volumes of chemicals generated as a result of any loss of process management must also be estimated in permit applications submitted by production plants to Tukes in addition to the volumes of stored or handled chemicals. 

Tukes will initiate several measures based on the recommendations

Based on the investigation results, Tukes will require more detailed clarifications and corrective measures from the waste processing and recycling plant to improve the handling and storage of waste. 

Tukes will also provide advisory and supervisory services for companies that send hazardous waste chemicals to help them better ensure the ability of waste processing and recycling plants to identify risks associated with waste batches and their capabilities to dispose of waste appropriately. 

Based on the investigation, Tukes will also specify permit and surveillance procedures related to changes in operations. 


Accident investigation report (in finnish), pdf

Presentation of the investigation, pdf

Further information about the accident investigation and report:

Timo Talvitie, Senior Officer, tel. +358 29 5052 654
Aatu Isotalo, Senior Officer, tel. +358 29 5052 243

Further information about measures initiated by Tukes as a result of the investigation: 

Kirsi Levä, Director, tel. +358 29 5052 162
Email format: [email protected]

* The CLP regulation is the regulation of the European Parliament and of the Council on classification, labelling and packaging of substances and mixtures.


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