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Trenchless trends

Ground Engineering canvassed the views on attitudes to trenchless technology, particularly for new installations, from a number of specialists within the sector, including contractors, consultants and equipment manufacturers. Below we present the key find

Is trenchless technology used to its full potential?

All agreed that use of trenchless technology is way below its potential, particularly for new pipe installations, where respondents estimated trenchless methods currently have a maximum of 15% of the market.

Attitudes have definitely changed in recent years although growth, most believed, is likely to be slow. As one responded, growth will depend upon the attitude of utilities who are the ultimate clients.

However some predicted that within a decade, trenchless methods could account for 50% of all new pipeline installations and there is plenty cause for optimism.

'Trenchless technology is finally becoming accepted in the UK as a mainstream alternative for pipelaying.

Over the next five to 10 years, we foresee rapid growth driven by the compelling environmental issues' says Steve Vick, managing director of Steve Vick International.

Have you ever encountered reluctance from clients to use trenchless solutions?

All had experienced reluctance, but for some it was not frequent. The main reasons appear to be a lack of understanding and poor awareness of the available techniques, inertia, bad experiences, inability to inspect work buried in the ground, and preconceived opinions about high costs.

High cost is probably the most common counter argument against use of trenchless technology, although most trenchless practitioners argued this to be a fallacy.

A major problem is the use of inconsistent techniques for price comparisons, says Gary Houghton of Perco Engineering Services. 'Very often, when comparing prices, clients will look only at the direct costs and will not take into account ancillary works associated with traditional methods such as open cut (eg traffic management, landfill tax, public disruption).

Furthermore trenchless technology requires proper up front engineering and investigation which most utilities are reluctant to undertake. 'Bad experiences' commented one, 'are invariably due to incorrect selection of a technique appropriate to the job in hand. This needs to take into account the prevailing ground conditions, installation size and length and the subsequent use of the facility.'

Balancing the associated risks and benefits is also a serious problem, said another, clients can be at greater risk should the method fail.

However Dec Downey, chair- man of Insituform Technologies and chairman of UKSTT believes: 'There is rarely a serious reluctance to use trenchless methods once they have been considered and the facts are exposed.

'There remains however a tendency to consider trenching as the first option. Open cut requires no special equipment or training. But the work is usually in the hands of specialists and requires more effort to manage.'

Are some trenchless techniques more widely accepted than others?

Renovation techniques, such as soft lining for sewers are greatly accepted, compared to new installations. Of the new installation methods, pipe bursting on clean water and gas are widely accepted, although pipe bursting on sewers is relatively new and needs to be embraced.

Directional drilling and pipebursting are very widely used in the small diameter utility sector, because market entry involves a modest investment and skills can be readily acquired. Microtunnelling in contrast, though well established, is perceived as a difficult and technically complex with higher mobilisation and market entry costs.

What factors inhibit the wider use of trenchless technologies?

Expressions such as lack of knowledge, client education, ignorance and inertia in utilities and consultants, and some cowboy contractors, featured regularly in responses. Other factors cited include:

Pre-conceived and inaccurate views on the cost-effectiveness and efficiency of trenchless methods

Reluctance to change from conventional construction work

Perception and quantification of intangible benefits

Reluctance to include environmental and social costs into the tender evaluation process within urban schemes Market entry cost Skills development Concern for underground obstacles In which areas of trenchless technology do you predict strongest growth in the next decade?

Nearly all respondents rated directional drilling as having particularly strong growth potential.

Pipe bursting and augerboring, especially in connection with sewer replacement/renovation, were also considered to be likely growth markets.

Guided boring has had modest success to date compared to North America and Germany, and in the light of the experience there, 'it seams obvious that this will be replicated in the UK' said one.

Others stressed the importance of greater use of underground mapping and sophisticated detection methods which minimise risk and should encourage the general growth of cost effective trenchless methods.

Thanks to the following who supplied the information on which this article is based Paul Norris, Mott MacDonald Steve Vick, Steve Vick International Gary Houghton, Perco Engineering Services Dec Downey, Insituform Technologies and chairman UK Society for Trenchless Technology

Utility room

Use of trenchless technology has grown significantly over the last few years as a result of several factors. New legislation such as New Roads and Street Works Act and HAUC regulations have encouraged both utility companies and their contractors to use no-dig methods.

Contractors have led the development of the technology and many utility companies have only recently become aware of the significant advantages offered - particularly in terms of environmental issues, customer care and general disruption to the public.

As utility companies have become more customer-focused, they have recognised the considerable benefits of a rehabilitation policy that embraces trenchless technology. As a result many utility companies now specify that a certain proportion of their work let to contractors is undertaken using trenchless techniques.

Furthermore, projects are increasingly being awarded on a design and construct basis and this allows the contractor to choose the most appropriate technique.

Growth in the use of the sector will undoubtedly continue. DETR has recently issued a consultative document Reducing disruption form utilities streetworks and this may generate further legislation which will encourage more use of new techniques.

The introduction of landfill and quarry taxes is also bound to drive companies to more environmentally friendly construction methods.

Hit for six Six

compelling reasons to use trenchless technology Reduces traffic disruption by drilling under roads and footpaths.

Cuts interference damage by 90%.

Directional drilling or moling disturbs only 3% of the ground disturbed by open cut methods. There are in the order of 75,000 interference incidents every year in the UK and it is estimated that trenchless methods could reduce these by 90%.

Minimises reinstatement scarring.

Helps organisations to comply with ISO 14001 by protecting the environment, eg drilling under tree roots and planted areas rather than destroying them.

Reduces energy consumption. A typical road crossing to install a 90mm pipe by open cut methods requires 6m 3 of spoil to be moved. A pit launched directional drill makes a hole of 120mm diameter for the same job - that is 0.2m3of spoil or 30 times less.

Reduces health and safety risks by minimising potential traffic hazards, dust from road saws, white finger, back injuries, dangers associated with trenches and noise

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