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Murphy stems the flow in the mains event


Thames Water has mounted a charm offensive to convince Londoners it is serious about stopping the leaks that spring from Victorian mains all over the capital. Damian Arnold joins the utilities company and contractor Murphy on the streets of north London to see how it is tackling the problem

REPLACEMENT of thousands of kilometres of leaky Victorian water mains is now officially Thames Water's top priority.

The utility has been mauled in the press for imposing a hosepipe ban and making healthy profits while allegedly neglecting its deteriorating pipe network that is spilling m illions of lit res of water each day.

In June, water regulator Ofwat announced that TW had failed its water leakage reduction target by 34 million litres per day. It is forcing TW to invest an ext ra £150 m illion by 2010 on pipe renewal. The alternative was for TW to pay a £66 million fine direct into the Treasury's coffers.

The £150 million will see an extra 230 miles of pipes renewed on top of the 1,000 miles it has already agreed to renew under its five-year asset management plan agreed with Ofwat in 2005.

The commitment will put more pressure than ever on TW's four main cont ractors, Murphy, Laing O'Rourke, Morrison and Clancy Docwra.

But the word from one of the contractors working the streets is that renewing London's water pipes is much more complex than the press would have us believe and that TW has already turned the corner.

'People say Thames Water is not reacting to the problem but it is, ' says John Chambers, Murphy construction manager for Victorian Mains Renewal in the Central/North London zone. 'We don't like to see Thames Water vilified when we are all working so hard together to improve things. It's unfair because it is making huge efforts.'

In the face of what TW calls 'deter iorat ing asset serviceability' in London's 30,000 km network of pipes, the challenge for the utility and its contractors is pinpointing the 1,235 km of works in the next five years that will have maximum benefit.

The key construction issue is to decide where it is possible to use faster techniques such as pipe bursting and insertion, which require less road possession time.

Pipe bursting, under which the new pipe is fed through the existing one, thereby peeling it away, requires far less digging up of the road. But it can cause problems that will see savings eaten up by financial time penalties imposed by local authorities for late f inishing.

Pipe bursting and horizontal directional drilling, under which a new pipe is simply fed under the road, are usually only risked if TW is certain about what assets are underneath the road. Damage to a nearby gas pipe, for example, could be very costly indeed.

'We only use these methods when we know there are no other services in the vicinity but our records of where gas, electricity and telephone services are can be quite poor, ' says Rob Archer, TW's project Manager for Victorian Mains Renewal in the North/ Central London zone.

Equally, with the insertion technique, whereby a smaller pipe is simply fed through the existing one leaving both intact, problems can emerge if the existing pipe is found to be too small.

'There is a risk because you don't always know what you're going to f ind , ' says Mr Chambers.

This is why many of the works visited by Construction News employed the traditional technique of digging up a whole section of road to ensure no other utility pipes will be damaged. It may be safer but it brings headaches of traffic management and site safety. This requires the contractor to work closely with TW to decide the opt imum t ime to dig up a stretch of road. For example, busy shopping areas are avoided in December and January when the streets are clogged with shoppers and busy junctions are tackled in the summer months or school holidays.

'When we have got a price and programme and we know what our methods are we contact the local author ity highways depar tment as well as local businesses, ' says Mr A rcher.

TW also talks to other utilities and highways departments about the possibility of co-ordinating works but this is often not workable, he says.

'We do get informed about new work going on and look at the possibility of sharing work but it's not always the best idea. We do it if it makes good sense but it's not a panacea. It's not like the advert on the telly.'

He points to examples where sharing of work has happened, such as at Bedford Square in Bloomsbury, where mains replacement work was accelerated to coincide with repaving.

On the day of CN's visit to the North/Central London Zone, many other complex construction challenges were illustrated.

'The biggest challenge is the scale of the work we have to do, ' says Mr Chambers. 'For example there are many different road surfaces and some of them such as cobbled squares require a lot of extra work and specialist expertise.'

Works teams also have to reinstate surfaces to very high standards under Highways Authority and Utilities Committee guidelines.

'After reinstating the road we are liable for three years and there's no way we want to be com ing back , ' says Mr Chambers.

Murphy and TW engage in met iculous plann ing with regular meetings to check progress on all sites but as someone once said, 'It's events, dear boy, events' that spoil the best laid plans.

Mr Chambers and his crew were all set to complete a major ser ies of works on Liverpool Road in Isling ton in May when they were suddenly informed that if Arsenal won the Champions League in a few days time, the trophy would be paraded around the streets and the all the works would have to be backfilled and started again.

'Things can happen very quickly and we often have to reschedule works and find somewhere else to go, ' says Mr Archer.

Another common problem is the extremely poor state of the existing steel and lead pipe work, corroded over many years by London clay wh ich, according to Mr Chambers, is par t icularly aggressive to the metal.

The majority of new pipe work, varying in diameter from 125 to 450 mm, is made of plast ic and designed to last more than 100 years.

Metal pipes may also have incurred extra damage in the dry summer weather. Subsidence mangles the steel pipework but plastic has greater f lexibility and can move with the ground.

Other occupational hazards for the works teams are making sure holes in the road are kept covered and not accessible to those still intent on playing the old trick of 'accidentally falling down the hole then mak ing a claim'. Mr Chambers adds that overly keen traffic wardens have also been known to climb site barriers and issue parking tickets to vehicles at a road works.

In an ideal world, the work would be done quicker and cheaper if there were more opportunities to turn off water supply and close off sections of road.

'It would be good if we could be more ruthless and cut the water off, ' says Mr Chambers. 'We could put the pipes in twice as quick but a lot of what we do is about retaining normality.'

Smart metering

AS PIPES get renewed, TW is embarking on a major programme to install water meters that are connected to the mains via a telecommunications cable welded onto the meter.

The long-term programme will eventually give TW a clearer picture of what it calls 'water balance' - the amount of water being piped in and how much is being used.

This 'real-time automatic meter reading' will give TW much quicker access to information about leakage. A trial of the equipment started in Angel in July but, says Mr Archer, it could be a long time before it is introduced all over London because of its high cost.

Under the system, TW is installing 'smart tags' which are not bat tery-operated next to the mains, enabling it to pinpoint location of the pipe to 10 mm at a depth of 1.5 m.

This will bring more certainty about the location of the pipe work, which could lead to less digging up of roads and more use of in-line installation techniques.