TPi September 2014

products & developments Trenchless rehabilitation of drinking water pipes

leakages, to guarantee an immaculate 24-hour drinking water supply for future decades. In autumn 2013, the Shumen Water Supply and Sewerage Company commissioned Stroitelna Mehanizatsia, a construction partner of Sekisui SPR in Europe, with the rehabilitation of a deteriorated steel pipe with a length of around 3,000m and diameters of 544 to 920mm. The project included four sections, three of which were rehabilitated by trenchless Nordipipe™ CIPP technologies from Sekisui SPR. For the rehabilitation of a 328m-long drinkingwater pipe section with diameter of 920mm, Nordipipe as pull-in version was deemed to be the ideal technological solution. Open construction would not have been possible due to the challenging construction site conditions. The 920mm diameter steel pipe lies in an unstable ground with soft, loamy soil, which meant limited accessibility, particularly during persistent rainfall. Therefore only a fast trenchless technology solution was considered, for which excavation pits as start and end point and less equipment was sufficient. Further difficulties that the technology

The challenges often involved in drinking water rehabilitation projects are the available time window, residual flow capacity after the rehabilitation, diameter and length to be renewed. Other factors are the capacity to negotiate bends and local construction site conditions. In Shumen, Bulgaria, the drinking water supply is managed by the Shumen Water Supply and Sewerage Company, which selected CIPP technology and instructed the rehabilitation of four sections in its water network. One section was a pilot project: for the rehabilitation of a 328m-long, 920mm diameter drinking water pipe, the CIPP liner system Nordipipe™ was used as pull-in version for the first time. The region is supplied by 94 individual and independent water supply systems, covering eight towns and 143 villages. There is 1,450km of local distribution pipeline, with 56,159 lateral connections, and water is supplied by pumping along 890km of pipeline to 72,209 households. Most of the pipes were made of asbestos-cement, and were constructed between 1950 and 1970. Others were made of steel that needed to be rehabilitated because of

Inversion of the calibration hose at a speed of 3-5m/min by a pressure drum to position the main hose in the old pipe

had to compete with were the high groundwater level, a strong gradient of 6-8%, a 15° bend and an operating pressure of 16 bar. Nordipipe consists of a main hose and a calibration hose whose material combination has been approved in conjunction with Nordipox D resin for potable water under various approval schemes in several countries. The main hose is a fibreglass-reinforced needle-felt liner with a number of glass

Nordipipe is impregnated with Nordipox D epoxy resin on a mobile impregnation setup close to the construction site

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Tube Products International September 2014

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