Drainage pipe installation with GRUNDOPIT 40/60

08.04.19 - The Polish town of Sady has a population of 890 and lies roughly 14 km north-west of the state's main city of Poznan, the airport of which, Poznan-Lawica, is just 13 minutes away by car. Dissecting the small town is the state road DK 92, a main road with 4 lanes. And passing close by Sady in the east is the motorway-like S11. The town is therefore extremely well placed strategically for industry and trade – and this is not just local knowledge: Across a wide area on the left and right of the state road is a row of huge buildings mainly from logistics organisations but also production halls from machine manufacturers, the food and packaging industry, building material suppliers, automotive supply outfits etc. as well as extensive warehouses from large online companies. The signs on the road and on the halls represent almost without exception companies and groups of companies that operate on an international scale.

Down and under

Over a roughly 1 km long section in Sady, it was necessary to completely renew the state road DK 92 (DK stands for Droga krajowa = state road) on which heavy trucks frequently drive. Associated with this new construction were of course also the new installations for effective rainwater drainage: six road drainage shafts and their line connections to existing drainage ditches. Since the road drainage shafts had to be placed in the central strip of the wide road during new installation, the respective pipelines (PE pipes OD 220 mm) – that are designed to direct the rainwater to the existing drainage ditches – had to be routed along a length of 12 m under the road in each case. When doing this, it was important to ensure that the lines had a certain drop.

Typical of GRUNDOPIT

To route lines from the road drainage shafts down and under the road, the horizontal flush boring method with a small drilling plant presented itself as the best option mainly due to the tight conditions and the very heavy traffic. To do this, the city of Poznan commissioned Nowo-Instal-Bud s.c. Pawel i Michal Swiergiel in Nowy Tomysl, 60 km away. The family-run business was founded in 1976 and is well versed in underground routing of all types of lines. It also has a good assortment of appropriate machinery. For the task at hand, they opted for a GRUNDOPIT 40/60, whose typical attributes include:

              -Controlled and steered drilling in tight conditions
                -High demands on precision
                -Fast, clean and cost effective execution
                -Compact and powerful – high power density

No sooner said than done

It turned out that instead of the six new road drainage shafts, only four of them needed a new line connection; two could be connected to the existing pipelines. For each of the four road drainage shafts, therefore, a hole of approx. 12 m had to be made under the road. Here, a pilot hole with a diameter of DA 80 mm was made from a small starter pit. The direction of the pilot hole (controlled gradient reduction) was controlled absolutely reliably with locating technology from DCI, a DigiTrak Falcon F1. With a pushing force of 40 kN and a flushing volume of approx. 20 l/min., the job was done in 50 minutes even though problems with the substrate were encountered unexpectedly: During drilling, demolition waste from the old road was found in addition to the normal road sub-structure (heavily compressed sand). An unexpected surprise that the drilling crew responded to quickly: Due to the unstable ground and also because of the gradient reduction, the integrity of the hole was at risk – not the best of things to happen under such heavy traffic. To ensure that there was no danger of the drill channel collapsing, the pilot hole was widened with a back reamer directly during reverse pulling and the PE pipes were drawn in at the same time.

Thumbs up

Overall, the team needed just two hours for each hole despite the unexpected surprise and without any tangible impact on the dense traffic flow. With the swivelling control panels and the compact dimensions, the mini-flushing plant GRUNDOPIT 40/60 has outstanding handling for tasks such as these. A small but powerful machine that the drilling crew handled with flying colours.



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