Probing technology minimises land risks

The recent use by the BBC Timeteam Series of Ground Probing Radar (GPR) for their archaeological investigations and historical sub-surface ground examinations has increased public awareness of the benefits of using GPR to locate non-metallic and metallic objects prior to any ground remediation or top soil removal for contaminated land disposal.

Integrated Environmental Technology Group plc (IETG), a data capture and management

company, has recently invested in GPR systems manufactured by PipeHawk plc.

These systems provide additional capability in utility location on contaminated

ground investigations and overcome the problems of resolution and depth of penetration,

which can affect the effectiveness of any survey.

The depth of investigation can vary from less than one meter in mineralogical

clay soils like montmorillonite to more than 5,400 meters in polar ice. There

is also the additional benefit that sophisticated correlation software can take

out back scatter and improve the visibility of the trace, which means the techniques

are particularly useful for locating fibre optic cables, where even the slightest

tear during excavations will disrupt computer and telecommunications networks.

The Health and Safety Executive (HSE) have laid down guidelines for ground

remediation activities. In their document Avoiding Dangers from Underground

Services they have set out a three-step process for minimising the risks. It

involves a full review of all existing record drawings, a well-defined process

for locating all metallic and non-metallic services and only then proceeding

to dig. Insurance companies are now looking at any incidence of land remediation

accidents to ensure that the HSE guidelines have been adhered to.

Ground remediation

Two recent projects have indicated the value and efficiency of using GPR. At

a recent building demolition and land clearance project in Brighton, Fitzpatrick

used the services of IETG to accurately locate and protect a major communication

system fibre-optic cable.

Because the object being sought was non-metallic, conventional radiolocation

techniques could not find the cable and the teams knew that even the smallest

interference to the cable during excavation would have resulted in severe financial

and project delay penalties.

In another case, Amec used the services of IETG to locate underground services

for ground remediation and clearance for National Grid infrastructure expansion

programmes. National Grid is now so convinced of the value of using GPR that

they are specifying its use on all similar contracts.

The benefits in cost savings may be difficult to quantify, but as utility clearance

surveys and any corporate risk reduction figures must take into account the

effectiveness of the location techniques, what it is worth to the client in

terms of ‘peace of mind’ is priceless.

Action inspires action. Stay ahead of the curve with sustainability and energy newsletters from edie