A number of unexploded ordnance (UXO) risk management consultants use the term ‘best practice’ in their marketing, implying that they use superior processes and procedures to manage the UXO risk of a site. Rarely do you see the term ‘good practice’ being used on a website or during a sales pitch. Psychologically, stating “we follow best practice” just sounds better than “we follow good practice” and gives greater confidence in the consultant’s capabilities.

But what is the difference between good and best practice and what does this mean to the project stakeholder paying the bill to manage the UXO risk?

So firstly good practice is defined by the Health and Safety Executive (HSE) as the minimum standards for successfully controlling and managing risks to the legal point of reducing risk to as low as reasonably practicable (ALARP) and satisfying the law. This is the minimum point where a project stakeholder is compliant with statutory legislation, primarily the Health and Safety at Work Act 1974 and the Management of Health and Safety at Work Regulations 1999.

In terms of UXO project management, sources of good practice include industry recognised guidelines such as the “CIRIA (C754) Assessment and Management of Unexploded Ordnance (UXO) Risk in the Marine Environment” and “CIRIA (C681) Unexploded Ordnance a Guide for the Construction Industry”. Should a UXO related workplace accident occur, the contents of these guides would almost certainly be considered as industry knowledge for a ‘reasonable person’.

A risk assessment by a competent person to determine the risk of an unplanned detonation to employees/personnel from an item of unexploded ordnance is therefore in compliance with industry good practice and the law. Invoking the precautionary principle (paraphrased as better to be safe than sorry) when considering the functionality of any prospective UXO during a desk-based risk assessment would also, in my opinion, be considered industry good practice.

Good practice may also change over time with technological innovation, increased knowledge of the hazard and changes in the acceptable level of risk controls currently being applied within the industry. Unfortunately, it generally takes a catastrophic event for what was considered the current good practice to become more vigorous, with the introduction of standards and revision of current guidelines. In the wake of such an accident, a more stringent set of procedures and measures that constitute a reformed industry good practice would very likely lead to an increase in UXO risk mitigation project costs.

Best practice is defined as any procedures or practices in excess of this legal minimum ALARP point that is good practice. Therefore any additional procedures or measures introduced will have the effect of further reducing the residual UXO risk but will increase costs to the project in terms of time, money and effort.

Besides the health and safety aspect of managing the UXO risk, there is also the project risk to consider. The unplanned discovery of a UXO on a site can bring operations to a halt, causing project delays as arrangements are made to safely eliminate the UXO risk. Such unplanned delays caused by UXO will increase project costs.

By assessing the risk of an unplanned detonation to subsea assets, such as subsea tools or cables by an item of UXO, is moving into what I would consider industry best practice for the management of the UXO risk. The risk to personnel may be considered tolerable and at ALARP due to the water depth and large distance separation from any UXO on the seabed, fulfilling the requirements under industry good practice and the law. However, the project stakeholders may see an intolerable project risk due to the potential delays or equipment damage any potential UXO may cause. This would require additional UXO risk mitigation measures to be applied to the project to reduce the project risk to a tolerable level.

The carrying out of a UXO risk assessment is clearly compliant with industry good practice, but it becomes greyer as to what that legal minimum point is for industry good practice is for UXO survey design, ranges of detection, and the classification of magnetic anomalies, sonar contacts and bathymetric contacts as either potential UXO or non-UXO. Whilst the CIRIA guides provide a high-level UXO project management overview, the guides do not provide a standard methodology regarding the detection ranges and classification of magnetic anomalies as either potential UXO or non-UXO, or where the application of industry good practice begins.

The ability of a UXO consultant to classify targets as either non-UXO or as potential UXO can save the project significant investigation costs whilst reducing risks to ALARP and operating at or above this industry good practice point. It can therefore be in the UXO consultant’s and the project stakeholder’s interest to push the envelope of target classification where it goes from being safe (scientific rigor applied) to unsafe (a gamble) when detecting and classifying whether a magnetic anomaly target is either non-UXO or a potential UXO.

This good practice point and the dark arts/methodology of classification of potential UXO targets are often not discussed between the UXO consultant and project stakeholders, with the methodology often hidden behind an excuse of propriety information. Neither is the risk appetite of each party discussed and where that sits in relation to what is considered to be industry good practice for the classification of targets.

At the most extreme form of best practice and the reduction of UXO risk to de minimis, is the investigation of every magnetic anomaly target found, regardless of whether or not it can be avoided. This method can come about due to the “concern for future generations and environment” argument (often from a project stakeholder not paying the bill), or playing on the feelings of a stakeholder’s imagination and dread, using images of UXO exploding left and right.

Although an admirable practice and great for marketing the green credentials, investigating and recovering every item of debris from the seabed will significantly maximise project costs in terms of time, money and effort. The project stakeholder may indeed want the nearest to zero UXO risk for both the project and personnel and want to eliminate the UXO risk as much as possible to avoid any future complications. However, it can come as a big surprise to the project stakeholder if this was initially unplanned and is suddenly a condition of the UXO consultant’s ALARP certificate.

Climbing down from this extreme best practice position, there are variations in the risk mitigation methodologies, for example, avoid all magnetic anomalies that can be avoided and investigate all those unavoidable magnetic anomalies regardless of the magnetic anomaly size and any correlating seabed sonar contact dimensions. Moving further still towards what can be considered the industry good practice point, is the inclusion of any correlating bathymetric / sonar contact dimensions with the magnetic anomaly and discounting those contacts interpreted as non-UXO contacts to further reduce the number of potential UXO targets.

Even closer still towards that good practice point, is the combination of side-scan sonar and bathymetry datasets and the use of modelling software such as Seequent/Geosoft’s Oasis Montaj and further classifying targets based on applying threshold values to the modelled output.

The application of modelling software (Oasis Montaj) when appropriately applied can significantly reduce the number of targets necessary for subsequent inspection and can reduce the project’s costs for target investigation. Even a small reduction of 10-15 targets for investigation could save one day of vessel time spent locating, uncovering and visually inspecting seabed targets.

However, a poorly designed survey specification, and/or a poor execution of the survey specification by the survey contractor, and/or poor data processing can lead to erroneous model results. Poor data can potentially generate further additional targets, incorrectly classify targets, cause future project delays and at worst cause a UXO accident during construction.

Other factors of a UXO survey are also grey regarding industry good practice, such as the magnetic response of surrogate UXO items to design a survey and the acceptable data gap criteria associated with the adequate detection of the minimum ferrous weight of ordnance that poses a risk of harm to personnel. I for one am not a fan of surrogate item magnetic responses being used to design a UXO survey and would certainly consider it no longer industry good practice. A lack of including a factor of safety when deciding upon a threshold value on the modelled output values from Oasis Montaj would also most likely be outside of industry good practice.

For a project stakeholder, best practice may not always be desired. It may be beyond their budget in terms of time and money and that good practice and the certainty of protecting their employees from UXO is sufficient. They may be willing to accept the residual UXO risk to the project and risk encountering smaller items of UXO, UXO located in deeper water, or the presence of UXO where there is no strong evidence of a UXO hazard.

Such discussions of what is considered good practice, the classification of targets and the risk appetites of each stakeholder needs to be considered in the early stages of a UXO project for an appropriately designed and budgeted UXO survey, investigation and clearance programme.