Jurassic Coast First for Onsite & Aqualiner
The world renowned Jurassic Coast, which covers some 95 miles of stunning coastline from East Devon to Dorset along the English south coast, is renowned as the first place in the world where fossils were found in the rocks which are now known to record around 185 million years of the Earth’s history and also therefore as the birth place of palaeontology.
Now the Jurassic Coast can record another first, which in time may possibly be seen as just as monumental and historical as the finding of fossils. This new claim to fame is that the Jurassic Coast at Portland, Dorset has just seen the world’s first commercial application of the latest development in pipeline rehabilitation technology, that being the new Melt-In-Place Pipe (MIPP) system known as Aqualiner.
Portland Project
The project to install the Aqualiner system was undertaken for client Wessex Water by its main rehabilitation contracting partner OnSite, which holds the exclusive Aqualiner installation licence for the United Kingdom.
Wessex Water’s sewer team, under the guidance of Julian Britton, senior engineer for Wessex Water, has according to Nick Weatherby, technical director of Aqualiner “Played a highly important role in the Aqualiner development process by providing, alongside other stakeholder companies, several test sites for trial installations where initial developmental teething problems have been ironed out and out of which this latest ‘third generation’ now commercial system has grown.
While the project on Castle Road — the first Aqualiner installation ever to be undertaken on a ‘paid for’ basis — may not have been the largest diameter or longest length pipeline ever to have been rehabilitated using lining techniques, it was a very significant project for the people of Portland as well as Aqualiner Ltd.
Castle Road forms part of the main one-way system serving traffic entering and leaving Portland Bill, which is the land mass which is almost an island on the end of a narrow land spit off the Dorset coast near Weymouth. The ‘island’ has one entry and one exit route handling two-way traffic flows to and from the mainland running alongside the eastern end of Chesil Beach. Therefore, any work that could disrupt the traffic flow along this sole access route could have very serious consequences for the local population, businesses and the two best known facilities operating on Portland Bill, Portland prison, which houses some 680 inmates and the vital Portland Naval Base.
The lining operation itself comprised the rehabilitation of just 23 m of existing 225-mm diameter clay sewer pipe which runs beneath Castle Road at between 1.5 and 2 m deep. The work was scheduled to be completed in just one working day including set up, clean, survey, line and site break down, all of which had to be completed with full traffic flow allowed alongside the working area. All works were completed using access via existing manholes serving the sewer ensuring no excavation work was required on the busy Castle Road.
To compare options, according to OnSite’s engineer, to complete this same project using traditional open-cut techniques would have required something in the region of seven to 10 days with much greater potential for traffic disruption, noise and environmental impact for the local population on a major scale.
In the event, the lining installation process began at about 10 a.m. and was completed by 12:15 p.m., or just 2 hours and 15 minutes.
Aqualiner
The Aqualiner system is in many ways similar to other rehabilitation systems currently available to the market but differs in some very significant ways.
Firstly, the Aqualiner system does not use resins or chemicals as part of the lining process. This is achieved because the liner material is specially designed to eliminate this aspect of an installation. The Aqualiner process is known as a MIPP technique. The MIPP technique uses a liner material that comprises a combination of glass fibers (for stiffness and strength) and thermoplastic polymer fibers (which, after processing, becomes the matrix that surrounds the reinforcing fibers).
The liner installation technique follows what at first glance is a relatively simple process. Once the old pipe is prepared, the Aqualiner material is winched through the host pipe over the length to be rehabilitated. The main liner is normally installed with a protective outer pre-liner to prevent wear against the host pipe wall during the pull-in operation.
A power umbilical is then fed through the liner from the reception manhole end to the launch manhole. The umbilical is then connected to a heater pig, which is placed just inside the liner. A liner inversion drum is positioned at the launch end of the process, which is fitted with an appropriate length of inversion calibration tube. The drum is then connected over the end of the host pipe anchoring one end of the liner material in place.
The heater pig is a vital component in the lining process. Once up to temperature, around 200 C, the heat from the pig melts the thermoplastic component of the liner material which pushed against the inside wall of the host pipe by the pig. The melted plastic then permeates the structural glass fiber material. As this process occurs the calibration hose from the inversion drum pushes the heater forward into the host pipe melting the next ‘section’ of thermoplastic material. Once started, the process operates continuously. At Castle Road, the advance rate of the heater pig was about 3 min/meter. As the heater pig advances, the umbilical is collected at the reception end of the lining run. On short runs, this can be achieved by hand or for longer runs the umbilical is wound on to a cable drum.
Once the heater pig passes out of a section of liner, the temperature of the thermoplastic material drops quickly causing the plastic solidify in place. Thus, the liner is formed. This process occurs over the full length of the liner until the heater pig emerges at the reception manhole completing the lining installation. The inversion hose is retrieved, equipment is removed from the manholes and the liner ends are cut into the ends of the host pipe. If lateral connections exist along the pipe length, these can be reopened using standard robotic cutters. In the case of the Castle Road project, only one connection existed on the lining run. Once this work has been completed, a final as built survey can be completed and the pipeline put back into operation.
Aqualiner, it is claimed, brings with it several advantages as compared with commonly used lining systems. The absence of chemicals in the lining process means that odour emissions are significantly reduced, if not eliminated, during the installation process. The shelf life of the liner is unlimited because the materials do not react over time and are not altered until the installation process is under way. A further significant advantage of the Aqualiner system given the absence of chemicals in the liner process is that its standard material content and the strength this offers makes it not only suitable for installation in sewer systems but also pressure pipes including potable water pipes.
The process is also reversible. By heating the liner to the correct temperature, the liner can be removed if required with all the materials being fully recyclable.
A significant advantage that is claimed by the developers of the Aqualiner system is that the fully structural liner that is formed using the technique comprises very strong component materials. This means that for any given load bearing requirement the liner material for an Aqualiner lining can be significantly thinner walled than more conventional lining systems. In the case of the Castle Road project, a 3-mm thick liner was required, whereas for a conventional CIPP lining a wall thickness of around 4.5 mm would have been required. Not only does this mean that there is less material to handle at a lighter weight, so less potential hazard for operatives, but also the cross-sectional loss in the final lined pipe is significantly reduced. With the very low friction coefficient inner wall of the Aqualiner, this may have the effect of not just maintaining but possibly improving overall flow capacity within the renovated pipe.
Distinguished Guests
As the Portland project was the first commercial operation with the technology anywhere in the world, Wessex Water invited David Thurston, mayor of Portland and alderman Les Ames, a long serving member of Dorset County Council, to witness the historic event on their home ground.
During the course of the lining operation, both visitors were shown the installation first hand and were given a full explanation of how the system works by Aqualiner directors Gerry Boyce and Archie Adams.
During the course of their look around the site Thurston and Ames said they were most impressed by the technology and were proud to think that Portland was able to play its part in the commercial development of such an interesting and innovative technology.
Commenting on the operation for Wessex Water, Julian Britton said: “We are pleased to bring new innovations to the market that benefits our customers. It has been a long road to get to the point where Aqualiner has become a commercial system that we are able to utilize. However, this first commercial project in Portland may well mark a significant milestone for the technology. In the same way that lining engineers remember the first ever commercial CIPP lining installation, this project could well occupy a similar place in the rehabilitation industry’s history for MIPP technology.”
For Aqualiner Gerry Boyce said: “This is a very auspicious day for the Aqualiner system. We have overcome some very demanding technological obstacles to get here but now we feel that we have a world-beating system to offer to the pipe renovation industry.”
Commenting, Dec Downey, Chairman of Aqualiner, stated: “Very simply, this is a key milestone for Onsite and Aqualiner in the planned roll out of the product in the U.K. We, at Aqualiner, are extremely excited by the significant global commercial implications having achieved our first customer installation.”
From the contractor’s viewpoint Bryan Lord, business development manager for Onsite commented: “Our association with the development of this new process has been demanding to say the least. Now with crews familiar with the necessary procedures and with a full understanding of the materials and installation requirements, we feel that we have a lining system that will be a leading technology in years to come and one that will enable us to bring to our clients a much wider choice when it comes to selecting the right rehabilitation system for their pipe networks.”
This article was submitted by OnSite, Oxfordshire, United Kingdom.
