Reconstruction of a 700 mm diameter steel sewer pipeline in Zaporozhie by the city utility company Gorvodokanal is one project contributing to the increasing popularity of trenchless techniques in Ukraine.
At the beginning of 2009, the company was faced with a challenge to replace a 1,225 m pipeline. Difficult as it appeared, the task was aggravated by additional complications. During its lifetime the inner diameter of the pipe had accumulated a thick layer of hard sediments and, as a result, the pipe cross section and its carrying capacity were reduced considerably. A further challenge was posed by the fact that some sections of the pipe happened to be encrusted with concrete as a consequence of numerous emergency repairs. In addition, the pipeline was buried quite deep in the ground, with some of its sections at depths of up to 4 metres. It is hard to imagine what the scale of material and labour costs would have been if the contractor had used the traditional open-cut method: the excavation at such depth and length would have undoubtedly created a lot of problems for the one million citizens of the city.
The job was performed by fitting and construction company MSK, who works in the field of trenchless construction and repair of underground networks. For the job, the contractor used a HammerHead HydroBurst 125, one of the most powerful static bursting machines manufactured by the USA-based Earth Tool Company (ETC).
The old 700 mm diameter steel pipe was replaced with a new 710 mm diameter PE pipe, increasing the output capacity of the sewer. The job was performed by using a step-by-step approach, with the new utility installed in segments of 75, 200, 150, 300, 200 and 300 m. MSK finished the job in only three weeks.
The accomplishment of the described project, quite important for the city of Zaporozhie and original for Ukraine in general would not have deserved attention of the international trenchless community but for the following detail – the replacement of the 700 mm diameter steel pipe was performed using the Hammerhead HydroBurst 125. The machine has a declared parameter for the renovation of pipes of diameters between 150 and 500 mm.
The question is how it was possible to achieve this and whether the contractor was taking any risk when using this machine for the renovation of a steel pipe of a larger diameter than envisaged by the machine characteristics. The answer is a definite ‘no’, as the contractor had modernised the cutting tools, while the ETC equipment had once again proved that the declared margin of safety is not a mere declaration.
This diameter is a record for the HammerHead HydroBurst 125. This job was the first renovation of a large diameter steel pipe carried out with a HammerHead machine – a national record.
