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26 | 27TH - 3RD DECEMBER 2015 | UTILITY WEEK Operations & Assets T he traditional image of streetworks is of a coned off trench or pit in the road or pavement, with weeks of disruption being caused while essential work to cables and pipework takes place. However, as part of an attempt to mini- mise disruption to residents and customers, cut costs and reduce health and safety risks, energy and water companies are ploughing ahead with no-dig technologies. What: Mini-mole Who: Scottish Power Energy Networks (SPEN) Details: This project aims to deliver a safer, less disruptive and more resource-efficient way of repairing and replacing low-voltage (LV) and service cables, so as to provide an improved service to customers. Traditionally this has been achieved through open-cut trenching, and SPEN highlights that this not only causes disrup- tion to traffic, but can lead to "significantly increased costs and inconvenience" when cables need to be laid under ornate or deco- rative paving. SPEN is working with Tracto Technik (TT) and IQA Group to develop a miniature direc- tional drill excavation unit, which would remove the need for open cut trenching. It is hoped the mini-mole will "create a safer, less disruptive and more resource efficient way for the business to carry out the repair and replacement of LV and service cables". The project, which is being funded via the Network Innovation Allowance, started in April this year and has a budget of £544,555. The initial trial period will come to an end in 2017, where the results will be reviewed, and the technology could be intro- duced into SPEN's business-as-usual plans. What: Cured-in-place pipe (CIPP) Who: Yorkshire Water Details: Earlier this year and in a UK first, Yorkshire Water trialled the cured-in-place pipe (CIPP) which effectively creates a new pipe inside the existing assets by creating a watertight lining inside it. The trial took place in March in Willerby, Hull, aer CCTV inspection of a pitch-fibre pipe revealed it too be in "particularly poor shape". Parts of the pipeline were said to be "flaking like old newspaper" and in places the 100mm diameter connection was down to half that due to deformities. Yorkshire Water hooked up an over- pumping system so the properties served by the damaged sewer remained linked to the wastewater network while the repair took place. Rather than digging up the gardens and driveways of these properties, Yorkshire Water adopted to go with the CIPP system. However, before this could be inserted into the pipelines, they had to be cleared. Once this was completed, the polyester liner was cut to size and impregnated with epoxy resin – a process known as wetting out. This was then "rolled like a burrito" around an inflatable bladder and pushed into the pipe, before it was inflated and pressed against the walls of the pipe. It was le for three hours to cure and aer being checked by engineers the repaired and upgraded sewer was recon- nected. What: Ice pigging Who: Severn Trent Water Details: Ice pigging was first trialled by Bristol Water in 2008, and in 2010 Aqualogy (which was set up by former Bristol Water shareholder Agbar) introduced its first com- mercial service for ice pigging in the water industry. Severn Trent trialled ice pigging its early 2014 in Shropshire following continuous problems with a stretch of sewer that kept overflowing and would have to have been replaced unless it could be successfully cleaned. Rather than pressing ahead with a replacement, which would have required digging up the pipes, the 1,184m stretch was cleaned when a block of slush ice was pumped down the clogged up sewer. Four hours later, the cleaning had been completed, and the flow rate had shown a "significant improvement" with the two pumps on the stretch of sewer showing increases of at least 40 per cent. Using the ice pigging technique, rather than pressing ahead with digging up and replacing the sewer also represented a 99.5 per cent saving for Severn Trent. What: Close-fit PE pipe lining Who: Northern Gas Networks Details: NGN undertook two trials with the Subterra pipe-lining technology with partners Radius Plus, one of which was a tier three gas mains in Castleford. This was effectively replaced with like-for-like new pipes without the need to physically dig them up. The Subterra Subline lining process involved rolling down the new pipe, and this process reduces the diameter of the new gas pipes by about 10 per cent. This compressed pipe is then inserted down the decommis- sioned pipe that remains underground. In Castleford, this process was used to replace a 740m stretch of cast iron gas mains. Equipment focus No-dig technology Utility Week looks at six technologies that are being used and developed to press ahead with the no-dig revolution. Yorkshire Water's CIPP Aqualogy's ice-pigging technology