From the magazine, HDD

Eliminate obstacles

With the Eliminator and the assistance of Akkerman’s crew of accomplished technicians, they successfully completed two 76.2 m drives of 686 mm inside diameter No-Dig clay pipe through non-displaceable clay and clay stone.

A member of the Akkerman sales team was informed of a project by a client, the City of Edmonton, where pipe installations were required in non-displaceable clay and clay stone. Akkerman and the City of Edmonton viewed this project as an ideal prospect for the Eliminator and soon organised the logistics. Using the Eliminator would prove to be a time saving alternative method for this gravity flow sewer alignment, which was designed as a ring-beam and lagging hand-minded tunnel with a carrier pipe followed by grout fill. The alignment had to maintain an accuracy of at least 51 mm for gravity flow.

An Akkerman technician and engineer arrived on-site to assess the project and meet the eight-man crew. They worked inside a 4.3 m diameter shaft at a depth of 14 m. The customer’s 4812A jacking frame, powered by a P275 diesel power unit, were used to propel the Eliminator through the ground connected to the 16 inch diameter 1 m long casings and hollow stemmed augers. The installation was a two-pass method. The first pass, consisting of the Eliminator attached to the casings and hollow stemmed augers, represented a mere three-day production time. The second pass, made with the 28.5 inch powered cutter head outfitted with an increase kit and the final product pipe, was completed in seven days. The tooling was recovered from a 3 m diameter reception shaft. The second drive produced similar production rates.

After two successful drives, the City of Edmonton purchased the Eliminator and accompanying tooling, adding to the versatility of their GBM system package for future opportunities.

About the Eliminator

The Eliminator is a new 406 mm diameter boring head designed to work with the GBM family of Akkerman tools that has been in service since 2001. Named the Eliminator, the cutter head excavates as the lead tooling in soils that are considered too hard for Akkerman pilot tube penetration, therefore eliminating the use of pilot tubes.

The Eliminator is optically guided using typical GBM guidance system components and a target which can be viewed through the string of hollow stem augers. The hollow stem augers are used to drive the cutter bit and transport cuttings back to the launch shaft.

Once launched, the Eliminator has the ability to be retrieved by pulling it back to the launch shaft. This functionality is extremely beneficial in the event that that there is a change in ground conditions so the operator can make a cutter bit change.

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