Chemical Decommissioning: Safety Challenges

VERY few people would dispute that chemical decommissioning can be an inherently hazardous exercise, but when faced with varying legislative standards, complex plant constructs and often unknown levels of contamination, operators could soon encounter even greater safety challenges than they first anticipated.

But where do the most significant safety hurdles typically lie?

Whilst the list is far from exhaustive – and every chemical decommissioning project is of course different to the next – there are three key initial safety considerations that operators need to be able to navigate when undertaking an assignment of this nature.

1. Common services

Just because a decommissioning exercise may mark the end of one asset’s useful life, this does not mean that adjacent facilities necessarily have the same destiny – in the short or longer term.

It is not uncommon for there to be several ownerships on a single site, and many plants will need to remain uninterrupted and in perfect working order, when the decommissioning programme is underway. This presents a number of decommissioning scheduling challenges, with both pedestrian and vehicular movements requiring careful coordination to protect the health and wellbeing of all stakeholders.

But the safety challenge is magnified further still, when considering that these different operators may use centrally-supplied site services – such as electricity, water, natural gas and compressed air –delivered possibly by a single company. Decommissioning teams therefore need to be prepared to work around these live, common utilities.

The financial and operational implications of a plant being taken offline would be catastrophic, but the EHS impact could be even greater if these services were compromised.

2. Partial demolition of a multifaceted site

Linked significantly to point one, is the challenge associated with clearing only part of a chemical site. Sometimes the land may be occupied by multiple operators, as eluded to above. But it is also common for even a sole chemical manufacturer to wish to decommission and remove only selected assets from their footprint.

It must be stressed that such partial dismantling and demolition programmes can be carried out without incident. In fact, the practice is relatively common. However, the safety challenges – and therefore experience levels required – are invariably far higher in such cases.

A simple piece of equipment, of relatively straightforward construction, may need to be unpicked from a complex petrochemical site for example. This asset may not be particularly hazardous, but if there is a highly explosive atmosphere only 20 m away within the same facility, this changes the parameters of the whole project – more specifically, the methodologies used to take down the structure concerned. Hot cutting techniques would be forbidden, for instance.

Once again, the nearby presence of operational chemical assets does not prevent the decommissioning from going ahead, but meticulous planning and methodology development by experienced engineering professionals, is crucial.

3. The unknown

Chemical decommissioning is already complex as no two facilities are the same. There can therefore be no ‘one-size-fits-all’ approach. This means detailed drawings and historic operational details are always sought to help build a picture of what the team will be dealing with when works commence. Planning is extremely tough without this project-specific data.

The number of safety challenges then typically start to rise the longer a plant has lain idle. Generally speaking, the more time that has passed, the greater the degree of unknowns surrounding the integrity of the structure, the cleanliness of the interior and even the state of the residues inside.

An asset may have been partially cleaned, for instance, but if it has been dormant for a number of years and pyrophoric catalysts are present, the consequences could be devastating when the structure’s interior is exposed to air. In fact, varying residues may remain – they may have solidified, reacted or changed state, and it is difficult to say with any certainty what will happen when decommissioning begins, if thorough studies do not precede any on-site action.

This emphasises the importance of carrying out feasibility and options studies, plus detailed hazard identification regimes, before any decontamination, demolition and dismantling contractors arrive on site. The more insight the team has into the construction of the assets, specifically how they were used during their operational life, their structural stability and any cleansing regimes executed since they were mothballed, the easier it is to bring the project to a ‘known state’. Risks are far easier to manage – if not mitigate entirely – when armed with this knowledge.