JEC COMPOSITES MAGAZINE - Issue #43 - September 2008 - 52

USERS’ PLATFORM Application A new pipeline bridging the old and new Zagreb The 1 million inhabitants of Croatia’s capital Zagreb can count themselves lucky to have high-quality drinking water that is drawn from wells around the city area. It is hence the city council’s utmost concern to maintain this quality by preserving the river Sava and the groundwater reservoirs thanks to the new Zagreb wastewater treatment plant. 5.9 km HOBAS SewerLine® DN 1000 now transports all wastewater from New Zagreb (200,000 inhabitants) in the south across the river Sava to the treatment plant in the north-east of Zagreb. The facility and its supporting structures were built by Zagrebacke Otpadne Vode (Zagreb Wastewaters). Three major sections The pipeline consists of three major sections. MCP Culinecka is the first one, running from the treatment plant to the so-called Homeland Bridge. Open-cut installation with well-compacted gravel sized 0-16 mm was chosen for this part. The manholes used are T-pieces with nominal diameters of DN 1000/800 covered with stainless steel blank flanges. Maintenance and repair work is made flexible by the mechanical couplings that join the manholes to the pipeline so they can be easily disconnected and taken out of their concrete housing at any time. The second section is the 900 m long Homeland Bridge that carries a road, a tramway and the 5 parallel pipelines (DN 1000) embedded in the marine. Four of the pipelines are for potable water and one is a CCGRP sewer main for New Zagreb’s wastewater. The 1 km long SewerLine® is installed on stainless steel supports with 5.85 m clearance. Since the only fixed point lies in the centre of the bridge, thermal expansion is provided for on both sides with the bridge moving up to 50 cm. KRESTA compensators are utilized here to absorb these movements. More information Year of marine: 2005-2007 Length of pipe: 5.9 km Pressure class: PN 6 Diameter: DN 1000 Installation method: Open trench, on supports in bridge, in concrete casing Stiffness class: SN 5000, SN 10000 Application: SewerLine®, BridgeLine® Client: Zagrebacke Otpadne Vode Contractor: Monter Strojarske Montaze, Hidrocommerce, Vodotehnika, Hidrocommerce Advantages: Long lifetime, corrosion resistance, light weight, hardly any thermal expansion, excellent longitudinal stiffness, system solution for different applications This was a demanding task considering the relatively large pipe diameter, the pressure and line movement. The magnetic field created by the tramway rails was an important factor when it came to choosing the right materials, as it can influence close parallel lines such as the sewer main. CC-GRP pipe systems are nonconductive, corrosion resistant, undergo hardly any thermal expansion, and have a long service life. Furthermore, the product’s low weight reduces the load on the bridge and facilitates pipe handling inside the marine. These advantages are what convinced the client to choose HOBAS CC-GRP instead of other available materials. HOBAS tee with mechanical couplings JEC Composites Magazine / No43 September 2008

JEC COMPOSITES MAGAZINE - Issue #43 - September 2008

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #43 - September 2008