|
|
Renovating a Sewerage Pumping Main in the Heart of England
 Insituform Blue® is a new division of Insituform Technologies, Inc. (ITI) devoted to the pressure pipe renovation business for both potable water and non-potable water networks. Insituform Blue currently operates in North America and Europe, with the latter office based in Paris, France. Both operating centres also offer support to the relatively new and expanding operational division of Insituform Technologies in Southeast Asia. The UK subsidiary of ITI is Insituform Technologies Ltd (ITL) based in Ossett, West Yorkshire.
In early October 2007 ITL started a project to renovate a sewerage pumping main running between the picturesque towns of Matlock and Matlock Bath, both of which lay on the edge of the Peak District National Park, almost equidistant between Stoke-On-Trent, Sheffield and Derby.
BACKGROUND
The project is known as Matlock Bath Phase 3 Pumping Main and is being carried for client Severn Trent Water. Planning of the works was undertaken by Insituform Blue’s engineers in association with the main contractor for the project GF Tomlinson Civil Engineering Ltd of Derby, the approved sewerage infrastructure contractor for Severn Trent’s North and West region.
 The pipeline route runs between Matlock, laying to the north, and Matlock Bath. Over the past few years the pipeline has experienced a number of bursts and it was this ongoing situation that led Severn Trent to look at options for its renovation.
Careful study of the renovation options available for the 1.4 km long pipeline showed that, due to the very heavy traffic on the A6 trunk road beneath which the pumping main runs, an alternative to open cut replacement would be preferred. The potential disruption that would have been caused by open cut with the pipeline running under the main road was also compounded by the fact that the pipe route also passed over the River Derwent at a point adjacent to the very popular visitor attraction known as the Heights of Abraham. The area being on the very edge of the Peak District National Park is always very busy due, in part, to the numerous tourist attractions, sights and picturesque villages in the area.
In the end, it was decided that the work would best be completed using the new InsituFold® lining system from Insituform Blue®, which was appointed as the approved lining subcontractor for the project. InsituFold® is one of two high density polyethylene (HDPE) pressure pipe systems offered by the company, the other being the InsituFlex® system. In essence these lining systems comprise a PE pipe which is deformed to fit easily inside the host pipe being renovated. The liner is then reverted back to its original round shape to form the required close fit lining.
The reasoning behind the choice of the InsituFold® system was that it not only offered a trenchless solution to the lining project, minimising the potential traffic disruption, but also offered a close fit, relatively thin walled liner within the host pipe which would ultimately minimise any loss of flow capacity so keeping flow rates to a maximum.
InsituFlex®/InsituFold® Linings
The InsituFlex® pressure pipe lining system has been under development by Insituform Blue since early 2006. Designed to answer increasing demand for pressure pipe lining systems in the water supply industry, the system drives circular PE pipe through specially designed rollers. A winch is also utilised to aid the passage of the liner through the host pipe. The rollers reduce the liner pipe diameter, allowing it to pass into the host pipe being lined. Once fully installed in the host pipe, the liner ends are expanded out and fitted with end connections. Next, the liner is filled with water and pressurised, causing the liner to revert towards its original diameter inside the host pipe and achieve a close fit. The InsituFlex® product is currently designed to operate in host pipes from 50 mm diameter up to 250 mm diameter.
 The InsituFlex® product can be designed to form either a fully structural lining using thicker wall, lower SDR value PE pipe or a semi-structural/interactive liner using a higher SDR value PE pipe. The latter relies on the host pipe having residual strength which the liner utilises to fully withstand internal pressures once in operation.
Parallel to this development, Insituform Blue® developed the InsituFold® lining system, which was used on the Matlock project. This system is appropriate for work in larger diameter pipes over longer distances. As the name suggests, this system forms PE liner pipe by folding it into a ‘U’-shaped profile to reduce its effective diameter for easy installation into the host pipe. To do this, the pipe passes through a specially designed ‘folding’ rig. On this rig a hydraulic pushing machine advances the liner pipe through guide rollers and pipe folding wheels. The end of the liner is attached to a winch at the reception pit which guides it through the host pipe during installation process.
To ensure that the liner does not revert in the host pipe until required, the folded pipe is strapped as it exits the folding rig. This strapping holds the folded liner in its ‘reduced diameter’ profile until the lining pull-in is completed. Once the pull-in is complete the liner ends are opened out using air bags and end connections are fitted. The liner is then filled with water and pressurised to burst the banding and re-round the liner, again achieving a close fit lining of the host pipe. The InsituFold® system can be utilised on pipe diameters from 300 mm up to 1,200 mm.
Both systems utilise a lubricating bentonite slurry which is painted on the outside of the liner as it passes into the host pipe in the launch pit. This slurry reduces the installation tonnages required to pull or push the liner through the host pipe, a significant requirement with longer lining lengths.
The InistuFold® system also has the ability to operate as a butt and pull process, where shorter lengths of pipe are joined together during installation to make up the final lining length, thereby reducing the overall site footprint.
MATLOCK BATH INSTALLATIONS
 As previously mentioned the total length of the Matlock Bath installation project is 1.4 km. Some 8 individual installations will be completed during the course of the work. The sections of lining required to complete the project will comprise either a 300 mm or 450 mm diameter installation. On the section of pipe from the start of the project up to a length of 107 m a 300 mm diameter will be used. For the remainder of the project up to 1,430 m 450 mm diameter liner will be required.
The PE pipe being used to create the liner comprises 450 mm diameter SDR21 PE 100 or 295 mm diameter SDR21 PE 100. These are provided as 13.5 m long sticks which are fusion welded on site to form the installation length required.
When asked about the project John Beech Business, development manager for Insituform Blue® said: “Despite working on a very busy main road with restricted highway space being available, Insituform Blue® and Tomlinson have demonstrated their ability to overcome these difficulties and produce a quality solution for the client.”
|
|