The 17th edition of the Lessons Learned Bulletin (LLB) examines industrial accidents in waste management facilities. The study is limited to accidents occurring exclusively in dedicated waste management facilities, excluding interim waste storage or other activities within production sites. It primarily focuses on waste treatment, storage, and disposal facilities, with emphasis on the safe handling of chemical hazardous waste. Incidents related to municipal wastewater and sewage treatment are excluded unless the accident circumstances extend beyond these activities. Incidents involving non-hazardous waste facilities are considered if the substances involved become hazardous due to loss of containment.

Please note: The accident descriptions and lessons learned are reconstructed from accident reports submitted to the EU’s Major Accident Reporting System at

https://emars.jrc.ec.europa.eu 

as well as other open sources. EMARS consists of over 1100 reports of chemical accidents contributed by EU Member States and OECD Countries.

The bulletin highlights those lessons learned that the authors consider of most interest for this topic, with the limitation that full details of the accident are often not available, and the lessons learned are based on what can be deduced from the description provided.

The technical report, including the study findings and lessons learned, is available at the JRC Publications Repository (JRC137778).

Case 2 – Fire in a hazardous waste storage facility at a treatment centre

Sequence of events

A fire broke out in an outdoor storage area of a hazardous waste treatment centre. The infrared alarm system triggered an immediate response from the on-site personnel. However, their attempts to extinguish the fire were hindered by the subsequent explosion of multiple aerosols. The emergency services were contacted and they extinguished the fire after about one hour. At least 11 tonnes of waste, including two tonnes of special household waste (SHW, also known as hazardous household waste, HHW) from waste collection centres, four tonnes of various packaging materials (pallets, crates, plastic containers, etc.) and five tonnes of rubber hoses were consumed by the fire. A plume of black smoke was released. However, measurements indicated no signs of toxicity associated with the smoke.

Important findings

• The fire originated from a stock of 60-litre plastic crates containing special household waste from waste collection centres, which had been delivered just before the weekend and had not yet been sorted

• The operator suspected that an exothermic reaction caused by the mixing of incompatible SHW may have been the cause of the fire

• The area used for storing unsorted waste, located at a distance from buildings, was not specifically considered in the site's hazard study, which did not include a fire scenario for this area. Also, the potential projection of aerosol cans was not taken into account, which could have caused a domino effect.

• Different types of waste, including aerosol cans and hydraulic hoses, were stored together pending sorting. The presence of these items complicated internal intervention efforts by generating projectiles and heavy smoke, posing additional challenges for fire suppression.

Lessons Learned

Importance of fire detection.
The utilization of infrared detection equipment proved pivotal in the early identification of the fire outbreak. Smoke, heat, flame and ultraviolet (UV)/infrared (IR) detectors enable the prompt detection of fire hazards or outbreaks, allowing for timely response, potentially reducing the severity of accidents and enabling more efficient emergency interventions. Therefore, to enhance safety measures, the appropriate detectors should be installed in areas where inflammable hazardous waste is handled, including storage, pre-sorting, pre-acceptance, rejection, quarantine, and processing areas.

Timely sorting and processing of hazardous waste.
Allowing hazardous waste to remain unsorted for extended periods increases the likelihood of accidents and incidents. Timely sorting and processing of hazardous waste mitigates the likelihood of exothermic reactions that may arise from the accumulation of unsorted waste. Accumulation of waste can occur due to various reasons including low operational activity, stemming from equipment or workforce downtime (i.e., holiday periods). Operators need to establish practices to address situations where unsorted waste exceeds the capability of the facility to handle the waste in a timely manner. For example, operators can request that delivery of waste be delayed, have subcontracting arrangements with other waste operators for handling excess volumes or in the worst case, refuse to accept the waste. Such practices require planning and procedures to support them and avoid last-minute decisions that inevitably result in the accumulation of hazardous waste beyond manageable levels.

Specific hazards associated with handling substances such as aerosols.
When handling hazardous substances like aerosols, it is essential to carry out comprehensive risk assessments that account for all operational conditions. These assessments should ensure that emergency plans are resilient and can effectively handle a wide array of potential scenarios, considering the type, variability, and quantities of waste present on-site. For instance, failing to consider a fire scenario in the unsorted hazardous waste area, coupled with the possibility of aerosol cans projecting, resulted in unexpected challenges during emergency response.

Implementing hazard and compatibility zoning.
Strategic zoning of areas based on the classification of hazardous waste could significantly reduce the risks associated with incompatible materials reacting with each other. Segregating hazardous waste based on compatibility ensures that incompatible waste is stored separately. This practice reduces the chance of accidental mixing or exposure to potential chemical ignition sources, thereby mitigating the risks of hazardous reactions. Storing wastes with similar health hazards separately also reduces the potential for cross-contamination and exposure to toxic or hazardous substances. Moreover, segregation allows for easier identification and management of hazardous materials during emergencies. Emergency responders can quickly assess the situation, identify the risks, and take appropriate actions to mitigate them. Segregation of hazardous waste should align with regulatory requirements, guidelines, and industry best practices.

Source: Aria No. 48274

Summary of findings from the analysis of chemical incidents in waste management facilities

The French Bureau for Industrial Risks (BARPI) in their 2016 report, “Overview of accident statistics on waste management facilities” stated that “the waste sector currently ranks as the 3rd most accident-prone industry.” The EU generated a total of 2,135 million tonnes of waste in 2020, with 4.4% of that classified as hazardous waste (Source: Eurostat). As the EU transitions to a circular economy, the need to meet hazardous waste treatment goals is expected to increase. Coupled with the introduction of new types of waste associated with emerging technologies, such as the end-of-life batteries from electric vehicles, waste treatment facilities may be exposed to new chemical risks.

The Major Accident Hazards Bureau (MAHB) of the European Commission’s Joint Research Centre conducted a study on 85 chemical events in waste management facilities over the period 1989 – 2022, particularly associated with the treatment of hazardous waste. The aim of this study was to identify typical failures, on both technical and organisational level, associated with accidents in these facilities. Although the focus of this study is on recipient waste management facilities, many of the good practices regarding operational procedures and organisational management are also relevant for regulators, waste producers, suppliers and consigners, and indeed some recommendations are directed specifically to these stakeholders.

Classification of waste and operational state

Impacts

According to the analysis, the events studied collectively resulted in at least 16 fatalities and more than 300 injuries worldwide since 1989. One of the most catastrophic events occurred in Leverkusen, Germany in 2021 where following an explosion at the Currenta waste incineration plant seven employees died and 32 more were injured with economic damages exceeding 20 million Euros. Offsite impacts were also frequent across the cases studied with over 125 injuries reported and the neighbouring community being alerted to confine indoors and/or evacuate in at least 15 cases. As a case in point, in Apex, North Carolina, U.S., in 2006, more than 17,000 residents were evacuated for at least 36 hours following a fire at the “EQ” hazardous waste treatment facility and more than 100 residents were hospitalised shortly for respiratory disorders. The economic impact of similar events was generally significant although not all cases included economic impact data. Overall, 19 incidents recorded such data, that when calculated together, represent a collective loss of over 77 million euros.

Initiating events

As shown in Figure 4, the JRC study found in most cases (32 cases or 38%) that mixing of incompatible waste led to unforeseen reactions initiating the accident sequence. In these cases, operational and/or organisational failures caused an unforeseen reaction during mixing of waste. The undesired reaction may have resulted from a number of factors, such as misidentification of the hazardous properties of the waste, poor training on the process or how to respond when an unexpected reaction occurs, and possibly also a failure to perform an adequate risk assessment for the process at hand.

Almost a third of the cases (27 cases or 32%) indicated the presence of contaminants or particular waste streams that should not be in the process (e.g., aerosols or batteries in a furnace). Operators were not aware of, or did not know to be concerned about, the contamination of the waste stream before processing or storing the waste.

In nine cases (11%) a failure in the process equipment, such as the agitator, granulator, dryer, or scrubber led to loss of process control. In two of these cases, the sealings that ensure the safe hose hookup on vessels during the transfer of waste failed leading to loss of containment. Corrosion affecting the mechanical integrity of vessels and leading to the release of the hazardous waste content was also reported in two cases.

The omission of safe operating and storage requirements, such as temperature control, resulted in fires and/or explosions in six cases (7%). In three cases, ignition of flammable substances took place during hot work operations and in three others, batteries under storage or during processing, short-circuited and ignited. 

Underlying causes and aggravating factors

As shown in Figure 5, the study revealed that poor operating procedures were the predominant underlying cause, contributing to 66 cases (77%). Additionally, the accident investigations showed that in many cases operators had failed to analyse properly the processes associated with the treatment and disposal of the hazardous waste streams. It appeared likely that in at least 32 cases (38%) process hazard analysis had failed to identify all hazards including, potential reactions or their full evolution.

Figure 5. Underlying causes (N=85)

Notably, poor process hazard analysis was interconnected with deficiencies in other underlying causes since hazardous properties were either poorly identified or not identified at all. Poor or missing process hazard analysis (PHA) was also likely related to a number of other incidents, where the study identified:

• Lack of adequate training of employees (23 cases or 27%). In these cases, employees were not trained, or very poorly trained, on identification of hazardous properties and on how to respond during a process upset

• Poor process design, including equipment and installations, which was found to be inadequate for ensuring operation within the safe operating envelope in 23 cases (27%)

• Inadequate emergency preparedness, since accident scenarios selected for emergency drills were either not representative of the identified hazards or hazards were not identified at all during the PHA in at least 18 cases (or 21%)

In almost half of the cases (39 cases or 46%), waste acceptance procedures, including analysis of the incoming waste, inspection and verification, were found to be inadequate or incomplete (see Figure 6). This finding was quite common in cases where operators accepted on-site hazardous waste that did not conform to the consignment documentation.

In some cases (8 or 9%), poor housekeeping or corrosion issues acted as underlying factors indicating poor inspection and preventive maintenance procedures while in six events, storage conditions were inappropriate exposing waste to substandard conditions (i.e., temperature/humidity/weather) or excessive waste quantities were held under storage.

The study also identified several aggravating factors for some of the cases studied. These factors magnified the consequences of the events without modifying their nature. In the absence of this factor, the event would still have taken place. These were mostly related to:

• Low level of activity, related mostly to workforce shortages (15 cases or 18%)

• Inadequate detection and monitoring systems to alert and mitigate loss of containment sooner (nine cases or 11%)

• Limited firefighting availability in six cases

• Presence of excessive waste quantities in three cases

Case 3 – Poisoning in a wastewater treatment plant during dumping

Sequence of events
Following an erroneous transferring operation, a release of chlorine was reported at a wastewater treatment plant. The event started shortly after a tank truck driver started transferring bleach into an aluminium polychloride tank leading to the release of chlorine gas. The transferring operation was stopped and three site employees were hospitalised. An 80m safety perimeter was set up, and the facility’s ventilation made it possible to evacuate the vapours via a chimney. Pedestrian traffic around the site boundaries was prohibited for several hours.

Important findings

• Mixing of incompatible products during transferring was attributed to a handling error. A technician indicated to the tank truck driver both by hand gestures and orally the specific transfer opening on the station’s manifold

• The consignment documentation was not inspected and the transfer checklist indicated in site procedures, was prepared and completed without the necessary checks ever taking place prior to the acceptance of the tank truck into the facility and the commencement of transferring operations

Case 4 – Error while transferring acid at a household waste incineration plant

Sequence of events
A release of chlorine took place at a waste incineration plant during transfer operations of hydrochloric acid (HCL) from a tank truck to the plant’s acid tank. The driver connected the transfer hose to the two vessels and initiated the transfer. After 200 litres had been transferred, the employee responsible for accepting waste noticed a chlorine release stemming from the tank while monitoring the tank’s filling level. He suspended the operation and sounded the alarm. Despite wearing individual protective gear (a cartridge mask), the driver felt faint but still managed to walk to safety beyond the transfer zone. Around 1,500 litres of HCL were fouled and no other impacts were reported.

Important findings

• The lorry was transporting three large, 1,000-litre bulk containers of acid and another one containing 10% sodium hypochlorite (NaClO) in a single compartment

• The bulk containers of HCl and NaClO were identical and relied on the same transfer couplings

• The driver had mistakenly hooked the plant’s acid tank to the sodium hypochlorite bulk container, which had been intended for another client, and initiated the transfer

• The driver’s mask was inefficient, as the cartridge had been used for several consecutive days

Source: Aria No. 43406

Lessons Learned, Cases 3 & 4

Be informed about chemical hazards in loading and unloading and implement appropriate practices to manage the risks.
Waste management operators often ignore the full range of obligations that accompany the business of managing hazardous waste. Just as they need to handle, process and store waste safely on the site, they also have to manage the interface with transport. They need to comply with legal obligations associated with dangerous goods transport in loading and unloading operations. No transfer operation should be based solely on oral confirmation to initiate.

Moreover, the safety management system (SMS) must include the implementation of standardised procedures for reducing the risk of chemical release during loading and unloading operations. For example, staff should be trained on these procedures and they should be clearly posted in the transfer area as a quick reference for the driver and other personnel involved. An efficient SMS should also address the inspection and replacement of components on personal protective equipment, such as cartridges in masks, especially for personnel at risk of being exposed to toxic releases during waste handling and loading/unloading.

Particularly for the second case, loading of waste at the supplier’s site should also take into account the consignment’s delivery order. Pre-arranging and dividing the containers, that are appropriately labelled would minimise the risk of transferring the wrong consignment to the waste recipients. Additionally, dividing and compartmentalising the waste according to the delivery order would have significantly reduced the risk of delivery to the wrong recipient. Incorporating digitised logistics applications on both the waste supplier and treatment facility involving QR codes on waste containers and QR code scanning during waste acceptance can also reduce errors in waste deliveries.

Establish and enforce criteria and procedures for accepting waste into the facility
Operators should not only require, but actively enforce acceptance procedures. These procedures at minimum should require that waste conforms with documentation and that the documentation clearly specifies the hazardous type of the waste. Labelling of waste containers with prominent and standardised information (including the chemical name, concentration, hazard symbols, and any other relevant details) should also match the consignment documentation. Pre-acceptance should also include physical inspection of the waste and/or containers and packaging to verify consistency with the documentation and checking for any signs of damage, leakage, or anomalies. All records related to pre-acceptance should be maintained for cross-reference and verification purposes.

Ensure competency and certification of employees.
Personnel involved in the carriage of hazardous waste, particularly in loading and unloading and in handling during deliveries.  Both consigners (delivery personnel) and consignees (receiving personnel) should be required to have a minimum competence, documented appropriately, that certifies that they have been formally trained in safety management relative to the operations in which they are involved. For example, in the EU, a UN ADR certification should be required for anyone involved in loading and unloading operations with training updates at the recommended frequency. UN ADR training covers all areas of safe procedures, including loading and unloading and emergency response, but also legal requirements for documentation, classification, labelling and packaging of dangerous goods.

Case 5 - Incompatible mix at a hazardous waste treatment facility

Sequence of events
During transfer operations at a Seveso hazardous waste treatment facility, a yellowish smoke with a chlorine odour was released through the vents of a 30-m³ vertical tank. The incident occurred while an experienced technician was transferring 1,800 litres of a solution labelled as "acid" from three 1,000-liter containers. The operator initially sprinkled water on the tank and later neutralized the mixture with soda, followed by rinsing the tank. Several personnel experienced eye irritations, and approximately 125 individuals from the facility and adjacent firms were confined indoors for three hours.

Important findings

• The three 1,000-liter containers were mislabelled and misclassified as acids when they actually contained a sodium chlorite (NaClO2)-based alkaline chemical product

• The misclassification and mislabelling were intentional, as a result of an agreement between the waste treatment facility sales representative and the waste producer, due to delays in obtaining a site acceptance certificate

• The technician had conducted a pH test on the incoming waste and measured a pH level of 9, but failed to notice the inconsistent labelling

• The preliminary waste analysis test conducted to verify compatibility was not representative of the reaction risks for the volumes introduced (100 ml extracted from the waste delivered for a tank containing 10 to 15 litres)

• The hazard analysis included risks related to mixing incompatible substances but not such large quantities

• Following the release, the operator sprinkled the tank causing the smoke to thicken

Lessons Learned

Establish a robust waste analysis plan.
A robust waste analysis plan should be in place to allow verification of hazardous waste against the documentation provided as well as adequate waste sampling. An operator must establish a comprehensive chemical and physical analysis of a representative sample of the waste. This information can be obtained through either the process of sampling and laboratory analysis or by relying on other relevant documentation (e.g., chemical data from the source/process that generated the hazardous waste, Safety Data Sheets, relevant chemical test data from previous tests that are still applicable to the current hazardous waste).

Establish pre-acceptance procedures.
It is essential that the operator has waste pre-acceptance procedures in place and responsible.  The procedures should establish that only designated personnel can accept waste into the site and these personnel must be fully trained on the pre-acceptance procedures. Discrepancies against consignment documentation vs. the waste containers’ labelling and the site’s pre-acceptance sampling findings should be addressed before accepting the waste on-site.  When the waste supplier has misclassified the waste, or where a representative sample has not (yet) been assessed, the waste should be held in a separate area, for a limited time period, until the true hazardous properties of the waste are determined.

Non-conforming waste should be kept in a separate monitored holding area with a clear time limit for resolving issues before the waste is refused, in order to minimise the site’s exposure to potential reactive components or other unknown hazards. Thorough checks of the waste received and verification steps should be part of the waste acceptance procedures before initiating any transfer. An experienced supervisor should be reachable at all times by staff, in case there is any question regarding acceptance of a delivery. All personnel should be trained on these procedures.  The holding area for waste prior to acceptance should be separate from any other waste, with appropriate safety conditions (e.g., temperature controls, separation distances from other waste), and instrumentation for monitoring the condition of the waste (including video cameras).

Incorporate strict waste rejection procedures.
The pre-acceptance process should also include instructions on how to deal with non-conformance, depending on the type of conformance, and clear criteria for refusing waste delivery. In addition to procedures for dealing with misclassified waste, the instructions should also ensure that waste is rejected if the supplier has not alerted the operator to the hazardous waste properties in advance so that the operator can determine that the site has the competence and capacity to conduct treatment and disposal safely.

Connect quality assurance with waste supplier management.
The study identified at least ten cases where waste suppliers were complicit in sending non-conforming/incompatible waste streams to waste treatment facilities. Such non-conformance could involve contaminated waste, mislabelled waste vessels, delivery of different waste than the one documented or the presence of other types of waste within the waste stream against consignment documents. Hence, waste rejection should be supported by a rigorous quality assurance (QA) and waste supplier management programme. This programme should be in place to facilitate documenting and analysing deviations from agreed-upon waste deliveries, fostering a culture of accountability and compliance within the waste management supply chain. Employees associated with waste acceptance and rejection should have access to this system and be able to provide relative information, particularly in cases where incoming waste is rejected. Generating Non-Conformance Reports (NCR) from the relative waste facility QA department plays a crucial role in eliminating the recurrence of incoming non-conforming waste.

Identify realistic accident scenarios and train on proper mitigation and response procedures.
Waste management sites should understand the hazards and what could go wrong in a treatment or disposal process. This requirement means that a site needs to analyse the range of processes and the range of interactions that could go wrong, based on typical mistakes that can occur, such as an insufficient analysis of the dangerous properties of the waste. To this end, past events and near misses are an invaluable input. The site should investigate chemical incidents and near misses to adjust scenario information, identify mistakes, and incorporate the lessons learned in their safety management systems. Understanding scenarios, and typical sequences of events, that could lead to a dangerous incident is required for process hazardous analysis and worker training, in particular.

In this specific case, the operator decided to sprinkle the tank with water which resulted in a thickened smoke. This action could have led to even more serious impacts since chlorine gas can react with water creating hydrochloric acid which would precipitate near the tank. Instead, the site should have had a rigorous process to prevent mischaracterization of the waste, but they should also have identified the ways that the process could have gone wrong and trained the employees to react properly. Although the correct action was taken during the sequence of events, the operator could have omitted using water and directly applied the caustic soda to minimize the release effects.  A safe response to this mistake could have been assured by training staff on how to respond to scenarios involving predictable malfunctions in the process.

Source: Aria No. 42944

Motto of the year:

“No one deliberately works unsafely…”

 (T. Kletz, ICI safety newsletter number 19, 1970)

You can access the eMARS database here:

https://emars.jrc.ec.europa.eu 

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