Going deeper underground

Marc Hobell, Jim Stancliffe

Beneath our feet in the UK lies a vast labyrinth of millions of kilometres of buried pipes and cables, delivering key products and services essential to our social and economic well-being. These networks of buried assets need repair and maintenance, and the growing demands of the UK economy mean that in years to come the networks will continue to grow significantly, as will the amount of traffic on the streets under which many of these assets lie.

There are now more companies involved in digging holes across the UK than ever before. Latest estimates put this figure at around 4 million holes dug by utility companies annually, and this excludes any excavations made as part of construction projects and works away from the street. Every time a hole is dug it impacts on traffic and the local environment. Often, holes turn out to be ‘dry’ – inaccurate information means that assets thought to be there cannot be found.

In addition, with every hole or trench dug or excavation carried out there is a risk of hitting and damaging buried equipment. The estimated cost of third-party damage to utility companies alone is approximately £150 million a year. This figure is dwarfed by the annual £5.5 billion cost to society through delays to road users, disruption to business, environmental damage and safety costs.

Of all the types of underground assets in the UK some buried pipelines are more hazardous than others, due to the contents they carry or the pressure under which those contents are transported. In the UK such pipelines are classified by the Pipelines Safety Regulations as Major Accident Hazard Pipelines (MAHPs). There are nearly 22 000 km of MAHPs in the UK with 20 000 km transporting gas above 7 bar, 1 000 km transporting ethylene and the remainder transporting spiked crude oil and other hydrocarbons.

Whilst these extensive networks are an efficient and low-risk means to transport large quantities of liquids and gases around the country, there is considerable potential for third-party damage to occur if excavation works adjacent to pipelines are not adequately controlled. In particular, where the pipelines enter urban areas or are sited near to communication routes this potential rises sharply. The consequences of damaging an MAHP can be devastating for people and the environment.

In the UK we have thankfully not witnessed the kind of catastrophe that can result from damage to an MAHP. However, on 30 July 2004 just such an incident occurred in Ghislenghien, Belgium. A high-pressure gas pipeline, operated at a pressure of 70 bar, ruptured following recent third-party damage. Twenty-five people died as a result and 150 were hospitalised, mostly with severe burns. It is thought that damage to the pipeline occurred during the final stages of a car park construction project as a mechanical soil stabiliser was driven over it. Two weeks after the completion of the car park the gas pressure was increased in the pipeline, which then ruptured with disastrous results.

Regular maintenance and upgrading of the UK’s MAHPs has revealed instances where damage has occurred to pipelines but has not been reported to the operator. The UK Onshore Pipeline Association believes it is essential for all cases of damage to be reported to the operator immediately. This applies even in cases where only the pipelinecoating or surface appears to be scratched, as this can lead to corrosion and a weakening of pipeline integrity.

Marc Hobell, Jim Stancliffe

Things can only get better

Currently, there is no national approach to the way information on the nature and location of underground infrastructure is captured, recorded and shared. Records are not always complete. There are varying degrees of accuracy and referencing approaches. The time it takes to capture, store, retrieve and share data, how it is stored and policies and procedures followed also differ. Even scales of drawings, level of detail and symbols used are not standard across organisations. All of these factors combine to reduce efficiency and effectiveness, and increase health and safety risks. But all this is on the change. Following the work of the ICE/ICES Geospatial Engineering Board, the National Underground Assets Group (NUAG) was established in 2005 to deliver a new way of looking at the issues. In July 2007 it published the ‘NUAG Approach’ for capturing, recording and sharing underground asset information.

The ‘NUAG Approach’ forms the basis of a national high-level framework to deliver a set of minimum performance standards. It envisages a structured transition towards more comprehensive data capture using GPS-enabled methods, more consistent data being held in GIS as well as webbased enquiry and information sharing. It also seeks to improve the quality and consistency of legacy asset data through an opportunistic approach, with no requirement to convert all legacy data from a stated date; rather, the aim is for an improvement over time. Implementation of the ‘NUAG Approach’ will inevitably take time. The performance standards proposed are deliberately challenging in response to identified stakeholder requirements and can only be achieved as organisations change their processes and the market responds with more affordable and useable technologies.

Stakeholders have identified the lack of a statutory common approach as a major underlying cause of the problems, and are supportive of the NUAG recommendations and standards. Using the ‘NUAG Approach’ as the basis for wider engagement with appropriate government departments, NUAG is making positive progress on key issues of ownership, legislation and resources. In agreement with the Department for Transport (DfT), and the Highway Authorities and Utilities Committee (HAUC(UK)), the July 2007 NUAG report will form the basis of the forthcoming review of their Code of Practice for Recording of Underground Apparatus in Streets.

As the next part of its overall plan, NUAG is currently embarking on a project to build on its work to date with wider support from the Health & Safety Executive, Regulators and wider government stakeholders such as DEFRA and the Scottish Executive. The ‘NUAG Approach’ sets out standards to ensure data on underground assets is more accurate, consistent and complete, and made available more quickly. It also sets out a high-level process for sharing and displaying asset information in response to enquiries. This new project aims to define and describe in much greater detail the necessary underlying processes, protocols and technological capability, and how they might be implemented, based on an understanding of user requirements and available technologies.

This will be the next step in moving towards achieving the NUAG vision: All information on underground assets, and appropriate associated above-ground assets, will be shared between stakeholders in a consistent way, on demand.

The costs and risks associated with the lack of a common approach are high, and will continue to grow unless action is taken to resolve the problem. NUAG’s extensive stakeholder engagement over the last two years confirms widespread and strong support for action to improve the situation. NUAG is trying to piece together a road map to enable everyone involved with buried assets to develop their organisations so that all reach a common point at an agreed date. Successful deployment of the ‘NUAG Approach’ is fundamental to this aim and to the delivery of significant associated benefits to utility companies, highways organisations, and society in general.

More information about NUAG, and downloadable copies of NUAG reports, can be found at www.nuag.co.uk.