TPi January 2016

products & developments Record size microtunnelling with Hobas CC-GRP pipes

In the Polish capital Warsaw, a 3.2km-long Hobas De 3270 pipeline has been microtunnelled on the left bank of the Vistula River to transport sewage and rainwater from the central and northern districts to the wastewater treatment plant (WWTP) Czajka. The new line will discharge the old Burakowski sewer, and represents an extension of the De 3000 jacking project that earned Hobas the ISTT No-Dig Award in 2011. Within almost eleven months, a new interceptor sewer has been installed via microtunneling along Marymoncka Street in Warsaw. Built from Hobas pipes with an outside diameter of 3,270mm, it is claimed to be the largest-diameter microtunnelling project to be implemented with CC-GRP pipes in Europe so far. The Burakowski-Bis interceptor com- pletes the sewer system leading from the left-bank Warsaw area to the WWTP Czajka located on the right bank of the Vistula River. Due to its limited capacity, the over 50-year-old Burakowski sewer could no longer handle the large amounts of combined wastewater during heavy rains. Its poor operating conditions posed a threat to the entire sewer

depth of 8 to 13m underneath the green belt separating the two lanes of Marymoncka Street. There was also a tram line running close by, as well as underground technical infrastructure. It was recognised that trenchless installation would considerably reduce excavation works and traffic disruption, as well as shortening the construction time of the new sewer line. Only a short, 47m-long section of the project was realised in open cut, on a green space alongside Słowackiego Street. The total length of the microtunnelled sewer line is 3,204m, and it consists of seven segments ranging in length from 107 to 613m. The first, and most demanding, section led from the launch pit at Dorycka Street to the receiving pit at the Maria Skłodowska- Curie Bridge. It had a length of 410m and included a 97m-long curve with a radius of 400m, which was implemented with 1m-long pipes. Due to the good lubrication and high- performance properties of Hobas pipes, the section could be realised without difficulty, with a maximum jacking force of less than 600 tonnes. The intermediate jacking station originally designed for this section was not needed, which made the assumed work progress of 10m/day increase to 16m/per day. Hobas Engineering GmbH – Austria info@hobas.com www.hobas.com

system and regularly led to emergency discharges of untreated wastewater into the Vistula, causing an ecological hazard. The construction of a new parallel sewer with additional retention capacity should allow for a higher level of environmental protection. The new sewer should also transport wastewater to the WWTP Czajka and make it possible to discharge and modernise the old sewer. Microtunneling was chosen as the optimal method for the construction of the Burakowski- Bis sewer for several reasons. The dense urban environment meant that the new line had to be installed at a

Precision ball valve with greater flow

and a relatively small orifice, that configuration is not always easy to find.

When Beswick introduced its 10-32 threaded ultra-miniature ball valves, the MBVMD-1010-303 ball valve won Design News Magazine ’s Best New Product Award in 2011. The MBVMD-1010-303 is suitable for many miniature, high-technology- type applications. However, when an application requires a precision ball valve that is more compact than traditional NPT threaded ball valves, but that can also provide more flow than is possible with 10-32 threads

The Beswick MBV-1414-3 ball valve is designed with 1/4-28 UNF straight threads and a relatively large orifice diameter of 0.125", and weighs only 34g. It provides more than three times as much flow area as the 10-32 threaded valve. Beswick Engineering Co, Inc – USA besales@beswick.com www.beswick.com

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Tube Products International January 2016

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