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Brownsdale, MN – February 12, 2013
A manufacturer and customer collaboration between the City of Edmonton and Akkerman this past fall, proved to be mutually advantageous. In fall of 2012, Akkerman put its new GBM system tooling, the Eliminator through the paces of real world testing in Edmonton, AB Canada. With the Eliminator and the assistance of Akkerman’s crew of accomplished technicians they successfully completed two, 250-foot (76.2 m) drives of 27-inch ID (686 mm) No-Dig clay pipe through non-displaceable clay and clay stone.
The Eliminator is a new 16-inch (406 mm) diameter boring head designed to work with the standard 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. Several cutter face bit configurations are available and can be tailored for specific ground conditions. While mining, steering changes are negotiated using three independently controlled, hydraulic shoes. The head is equipped with high pressure jetting nozzles to supply lubrication to the cutter face bit during operation. 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.
A member of the Akkerman sales team was informed of a project by customer, 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 organized 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 2-inches (51 mm) for gravity flow.
The contractor, The City of Edmonton designs, constructs and maintains all of their sanitary and storm water services through their Drainage Services Branch. They began providing pilot tube microtunneling services in 2008, with the addition of an Akkerman Guided Boring Machine (GBM) 4812 jacking system.
An Akkerman technician and engineer arrived on site to assess the project and meet the eight-man crew. They worked inside a 14-foot (4.3 m) diameter shaft at a depth of 46-feet (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-meter 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 (see Figure 1) represented a mere three-day of production time. The second pass, made with the 28.5” Powered Cutter Head (PCH) outfitted with an increase kit and the final product pipe (see Figure 2), was completed in seven days. The tooling was recovered from a 10-foot (3 m) diameter reception shaft. The second drive produced a 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.