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.
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.
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