WET News

14 WET NEWS JUNE 2014 One of the wastewater pipes to be lined with the 2.2m long patch liners TECHKNOW • Epoxy resin impregnated, ambient cured liner was installed in one length of 2.2m long and 800mm diameter • The technology offered a fully structural design capable of withstanding negative pressure • A 'one-piece' system that would cover the complete length of the renovated pipeline • Liners were assembled above ground and lowered the 17m using electric hoists • Measurements were taken to confirm the pipes' suitability of the proposed system THE VERDICT • Experience of large diameter and long length part-liners has helped innovate the rehabilita- tion and extension of life for existing pipework • The innovative design process has allowed liners not normally associated with negative pressure environments to be used • Bespoke solutions to a specific contract will help develop the envelope for other trenchless opportunities ONSITE Pipe renovation possible to exactly determine the diameter because the pipe, being a live sewer, meant that iLine could not get to the inside of the pipe. This also meant the precise internal condition of the pipe was unknown. The eight pipes in question were at the bottom of the chan- nel, 17m below road level and there was no vehicle access to the bottom of the well. A further limitation was that access to the valve side of the pipe was only moderate, with only enough space for two peo- ple and small tools to be utilised. Access to the other side of the pipe was technically possi- ble, but not great as this was the inlet channel from the main sewer and therefore came with a significant high risk factor, a requirement for confined space access and working. The deep channel was con- stantly full feeding the eight 800mm diameter pumps. Early involvement started between iLine Technologies and GCA in early June 2013, some five months before actual construc- tion work took place. This early involvement meant that protection system and rehabilitation systems could be planned to meet potential obstacles during the works including: • Flexibility to allow for possible changes in diam- eter during the construc- tion phase • A quick to install system given the tight time scale requirements during the construction works • A structurally sound sys- tem that could withstand negative pressure which would occur during pump shut down or during back washing • A 'one-piece' system that would cover the complete length of the renovated pipeline • An end sealant to prevent any tracking of water between the host pipe and renovation system The benefits of early inclu- sion of all parties and stake- holders during the planning phase had many benefits to the project when it ultimately took place. These benefits included early establishment of a regular programme of management meetings that ensured all par- ties were fully up to speed; short communication lines that meant decisions were made swi‹ly; a one team mentality that allowed for shared ideas and a high regard for safety was instilled in all those working at the site. The early inclusion also meant that mock-ups and sam- ples of the proposed lining could be provided and trial installations could take place to ensure everyone was happy with what was proposed. The project was located in the industrial area and old port of Liverpool and the works were located within the current con- struction site at Liverpool WwTW. However the actual renova- tion work focused on a major element of customer care, as the eight pumps li‹ed raw sew- erage into the treatment works. Preparing one of the liners for insertion The patch liners during the installation process. SHARE YOUR OPINION... yoursaywn@fav-house.com The works required four of the pumps to be decommis- sioned at a time during the ren- ovation leaving only four working. As such, the works had to be planned to coincide with expected low flow times with constant monitoring to pick up any potential increase in flows. iLine Technologies proposed the use of an epoxy resin impregnated, ambient cured liner that would be installed in one length of 2.2m long and 800mm diameter. Such liners could be installed in all eight pump feeding pipes. The material chosen met several requirements including: • It met with extensive wear tests undertaken by inde- pendent accredited testing houses • It offered a fully structural design which was able to withstand negative pressure • One complete length could be installed with no joints along the installa- tion length • Site specific installation equipment could be man- ufactured for this work site • It offered compatible end sealing epoxy The use of epoxy liners is well-known but what made this project "unique" was the involvement of several external experts in pipeline renovation, including Trelleborg, the mate- rial supplier of resin and patches; trenchless consult- ants, who assisted in the struc- tural design works; Sika Chemi- cals, which supplied the end sealant; and Exovia Testing, which provided final testing of the installed material. Rehabilitation Prior to the final go ahead and work starting on site, a sample installation was undertaken on an unused section of what was believed to be a similar pipe to that being renovated. A‹er installation and inspection, final approval for the works was granted. In November, four of the eight pumps were isolated to allow the rehabilitation work to proceed. The flow was diverted further upstream and warning systems put in place to con- stantly monitor flow levels. Once isolated, the pipes were accessed and cleaning was completed. Detailed measurements were then taken to confirm the pipes' suitability of the proposed sys- tem. Liners were assembled above ground and lowered the 17m using electric hoists. The installation equipment had been specifically designed and manufactured in Germany some four weeks earlier to ena- ble programme dates to be met. Once in position the liners were ambient cured for eight hours each. To enable the programme date to be met 24-hr working was undertaken to ensure suc- cessful completion and the min- imising of flood risk. Once cured, the liners were sealed and testing was under- taken by Exovia prior to the flows being returned. This test- ing was expedited to gain initial results in just 24 hours. As all liners were installed correctly and the testing confirmed this the flows were returned. iLine installed the other four liners in a similar process. Overall the project was com- plex and challenging but with all parties working together it demonstrated how innovative engineering solutions can over- come difficulties and deliver outstanding results. According to John Beech, business development manager for iLine: "Whilst to many look- ing casually at this project it may appear to have been just a few short liner patches. In truth, this was something of a com- plex and challenging operation given the location, depth, size and length of the patches involved. "The need to ensure the plant was kept operating whilst the renovation took place also added to the stress. Our team, working alongside and closely with the client teams and the various manufacturers and services involved, has achieved something with this project that few thought was actually possible." n MOANS AND GROANS 1 Being a live sewer, iLine was unable to get to the inside of the pipe 2 Ensuring the plant was kept operating whilst the renovation took place added to the stress All the world's a stage

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