Faced with the complexities of laying traditional ductile iron pipe or PE barrier pipe in contaminated ground at a housing development on the site of an old pottery in Liverton in Devon, South West Water’s framework partner Balfour Beatty Utility Solutions (BBUS) turned to Saint-Gobain PAM UK for an alternative solution.
The development of 11 social housing homes required a 5 bar water supply from South West Water, connecting from the nearest existing main with various service connections for the two to three bedroom houses. However, when it was confirmed that there was ground contamination at this old pottery site, there was a clear requirement for a pipeline that could protect the potable water inside.
Following in-depth analysis of the project, it was decided that Saint-Gobain PAM
’s innovative small diameter Blutop™
pipe could deliver the installation benefits of ductile iron
– ease of jointing, no requirement for imported backfill – at a lower material cost than the PE barrier pipe. In addition, Blutop™
had the ability to provide the answer to other problems faced by BBUS on this particular site.
David Cunningham of BBUS explains: “The most common problem associated with the current method of installing small dimension PE barrier pipe can be when restricted space makes it difficult to use an excavator to draw and hold the pipe. Further difficulties often experienced include the excessive effort required by the mains layer to achieve the coupling of installations and connections, the tearing of the pipe when it is being cut resulting in wastage because of uneven ends, and also the force required by the mains layer to control the coil as it is released from the pipe trailer. We found that these, and many other problems, were negated when Blutop™
pipe was used at the Liverton project. Because of its light weight, Blutop™
is manually manoeuvrable around site and, when lubricated, the main is easily pushed together via the use of a metal bar which, in turn, eliminates the need to use an excavator. Also, the 6° tolerance in the pipe collar allows the main to sweep around the trench line eliminating the need for extra fittings, saving on joints and overall cost.”
The Liverton project was the first time BBUS had used Blutop™
pipe and feedback from the operatives undertaking the Blutop™
trial was very positive. They were particularly impressed with its simplicity of use and manoeuvrability, and the heightened control by the mains layer in its application when laying and attaching installations and making connections.
Paul Hancock of Saint-Gobain PAM UK
explains: “A pipe bundle could be placed at a point close to the excavation and individual pipes picked up and transported to the installation point by two men without the need for any mechanical lifting equipment. There was a requirement for a change in the trench direction due to a need to avoid road gulleys, making it necessary to produce a “dogleg” within the excavation. This caused some concern that more Blutop
bends would be required to overcome the “dogleg”. However, due to the 6° of angular deflection available at each Blutop™ joint the need for extra bends - and additional cost - was avoided.”
During excavation, existing services crossing the trench were unearthed. If coiled PE barrier pipe had been used, negotiating the obstruction would have been a time-consuming and costly exercise, as the pipe would either have had to be withdrawn to thread through the services, or cut and the joint fuse welded. By using Blutop™
pipe, the operators were able to quickly cut to the right length and position the cut pipe under the services, ready for the next pipe to joint. This took approximately five minutes compared with up to 30 minutes if using an electro fusion method, and removed the requirement for specialist equipment on site.
Paul Hancock continued: “The BBUS team undertook the Liverton installation to compare Blutop™
against both PE barrier pipe and traditional ductile iron
. Against Natural® ductile iron pipe, it found the lighter weight (only 36kg per pipe) to be a major benefit. Pipes were very easy to manually handle and lay, saving time and money compared with using machinery.”
The team found it easy to locate the innovative Blutop™
gasket in the socket (“fitted within seconds”) and the low insertion force meant that the joint could be made using a crowbar rather than a digger bucket.
The 6° angular deflection at each joint eliminated the need for small angle bends and in turn, saved on extra gasket and assembly costs. It was necessary to fit an inline tee for washout purposes which, under normal circumstances, would require the use of a Redman (fluid compression) fitting. By using Blutop™
, the installation time was reduced dramatically and a material cost saving of 10 times that of the Redman fitting was achieved.
The ergonomic design of the fittings was also appreciated. In particular, the BBUS team was impressed with the design of the new handle which increased manoeuvrability and reduced insertion time aligning the next pipe.
Compared with PE barrier pipe, BBUS operatives felt that avoiding the need to ‘fight’ with coiled pipe was a definite benefit. They found the 6m lengths of Blutop™
‘just right’ for laying quickly with limited on-site cutting required, and welcomed the fact that push fit joints could be made in less than a minute compared with around 30 minutes using mechanical fittings required with PE barrier pipe.
Paul Hancock concluded: “Overall, Saint-Gobain PAM
provided BBUS with a solution that afforded the same protection as barrier pipe to potable water mains in contaminated land. In addition, it provided simplicity in its application and offered heightened control by the mains layer and proved to be a cost effective comparative to the currently used materials.”