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Specialist debuts vacuum excavation system in UK


A NEW specialist contractor has been set up to capitalise on the advantages of an innovative vacuum excavation system.

Excavation Technology has been launched by former McNicholas director John Knight to make use of the Servac II trenchless system, which claims the ability to drive boreholes without damaging services.

The system, revealed by Construction News in October, is being used on the upgrade of the West Coast Main Line, where contractor Balfour Beatty is installing a lowvoltage power cable running to a new electricity substation.

A section of the route between Watford and Elstree in Hertfordshire runs along a main road and interfaces with a large number of existing services.

A ground radar survey was carried out prior to the start of works and this revealed the location of services, but the vacuum system was called in as a precaution to excavate 150 mm trial holes at various points along the route, to determine exactly what lies in the path of the new cable duct.

The Servac II system works by loosening the ground with a fine spray of earth and water applied with a lance. The disturbed soil is then vacuumed out without touching the services.

Whereas previous vacuum excavators have suffered problems with blocked filters, the Servac II design avoids this by incorporating a dump valve immediately behind the vacuum hose, from which the soil is deposited alongside the excavation.

According to Mr Knight, there is no change in the soil's moisture content, and no problem in using it for reinstatement.

Mr Knight said the system's productivity in normal excavation work is equivalent to a two-man gang at a competitive cost.

Although the up-front cost may be more than conventional techniques, which the company also offers, the bonus provided by the Servac system is that there is no danger of damage to even the smallest BT cable.

Excavation Technology is currently the only contractor with the system in the UK.

Mr Knight said it has already aroused considerable interest, with potential clients and contractors visiting the current contract.

He said increased use of such a system could end the days of services interruptions caused by an unlucky pass with a backhoe.