April 5, 2011 KenKar Plastics Supplies 1200mm Polyethylene Pipe to Mardi Dam

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In January 2011, KenKar Plastics successfuly delivered 295 metres of 1200mm SDR11 PN16 PE 100 Pipe to Mardi Dam in Wyong NSW. The pipe was made by Agru in Austria and then shipped in containers, decantered and delivered to site. KenKar Plastics coordinated the delivery to coincide with the Horizontal Directional Drilling stage of the pipeline. This is the first project in Australia where pipe of this size and class has been required. No local manufacturers could guarantee the supply of 1200mm SDR11 PN16 pipe which was when KenKar Plastics entered into discussions. UEA completed the first installation of 1200mm SDR11 PN16 HDPE water main in Australia using a Horizontal Directional Drill (HDD). This bore was under the Wyong creek crossing that formed part of the Mardi to Mangrove Link Project undertaken by John Holland for the Gosford City Council and Wyong Shire Council, using $80.3m in Australian Government funding from the Water Smart Australia programme in addition to $40m from the councils themselves. The project called for a 2.1km buried water pipeline from the Wyong River to Mardi Dam, a 19km buried pipeline through the Yarramalong Valley from Mardi Dam to the existing Bunning Creek Tunnel , 2 new pumping stations and associated works. UEA subcontracted to John Holland for the HDD works. The creek crossing was originally planned as a micro-tunnelling project but ground conditions and the depth of the required shafts (10m +) caused John Holland to look for alternatives. Because 1200mm PE water main was not available in Australia and had not previously been installed by HDD, it was not originally considered but UEA found a pipe source in Austria and calculated that its Vermeer D300x500 directional drill rig was capable of installing this pipe in the prevailing ground conditions. A 60” (1524mm) diameter hole was required for installing the pipe, which was at the limits of the Vermeer. Apart from the difficult ground conditions (alluvial clay, sand, gravel and sandstone), a further challenge to the project was provided by the difficult access, with a narrow 10m wide construction corridor over 1.2km providing access to the exit point. A pair of 180mm pipelines was used to return drill fluid from the entry to the exit site. KenKar Plastics (KenKar) sourced the pipe from Agru in Austria on behalf of John Holland, as this size pipe was not available from local manufacturers. The pipe was shipped to Australia in 11.8m lengths, packed in 8 x 40ft containers. The containers were decanted in Sydney, transported to site by semi trailer and stockpiled there for later welding. The pipe and welding equipment had to be tracked overland by a 40t excavator due to the poor site access. KenKar was responsible for the butt fusion welding of the pipe, as well as the supply and fitting of steel test plates (81mm thick) to the end of the pipe string for pre installation hydrostatic pressure testing. Upon completion of the welding the pipe string was pressure tested to 1600kPa to prove the integrity of the welding process. The pipe string was pressure tested again after installation into the HDD bore. KenKar used its existing Rothenberger 1200B butt welder, which was modified slightly in order to boost the welding pressure to that required for this project. The butt fusion welding was carried out in accordance with European Standards (DVS) as per the recommendations of the pipe manufacturer, as the local welding standard did not cover pipes of this wall thickness. Despite the many challenges, UEA completed the bore successfully in early June 2011. The milestone in installing 1200mm HDPE pipe via HDD has led to inquiries from other water authorities, and is causing a rethink in the industry about what can be achieved with HDD methods, which provide significant environmental benefits from reduced ground disturbance over traditional open cut methods.