Scottish Water’s in the zone when it comes to leakage

For two consecutive years Scottish Water has been criticised by its regulator for not meeting leakage targets. It has been using SebaKMT equipment in its battle to reduce leakage levels. Maureen Gaines reports.

Scottish Water is on a mission – to drastically reduce its leakage levels. Over the past two years, the company has seen its leakage level drop but not by enough to meet the target set by its regulator, the Water Industry Commission for Scotland (WICS).

According to WICS’ investment report for 2007-08 Scottish Water decreased its reported leakage from 1,004Ml/day to 924Ml/day. The utility’s target was 855Ml/day. The target for 2008-09 is 855-825Ml/day based on a like for like comparison with previous years.

WICS said in the 2007-08 report: “This is the second year running that Scottish Water has missed our leakage target. Indeed, it has missed the target by more than in 2006-07 in both absolute and percentage terms. Although Scottish Water is beginning to make progress, leakage is still much too high.”

The regulator added: “While Scottish Water is working with us to improve the way it measures leakage, it must take the practical action necessary to tackle leakage and progress quickly to the economic level.”

Top priority

Scottish Water is doing its utmost to reduce leakage to acceptable levels.

Last summer it doubled the number of engineers and technicians as reducing leakage continued to be a top priority.

Back then, Richard Ackroyd, Scottish Water’s chief executive, said: “Over the past two years, we have reduced our reported leakage by 180Ml of drinking water. While this achievement is on par with the companies south of the border when they started tackling leakage it is still not good enough.

“Leakage has become ever more of an issue with climate change, the increasing cost of treating water to the highest standards and ensuring that we deliver better quality drinking water to our customers while increasing efficiency. We are well served in Scotland with water to supply all our customers and tackling leakage is part of our drive to become a more sustainable business.”

The company has identified five ways in which to address the leakage issue:

  • Locate and repair more leaks by investing in additional resources
  • Repair leaks faster – this has been reduced from an average of 15 days to five
  • Better pressure management through the installation of further pressure control valves
  • Managing service reservoirs better – telemetry and control valves are being installed
  • Mains renewal

In addition to increasing staff numbers working on reducing leakage, Scottish Water has been installing measurement equipment in District Monitoring Areas (DMAs), a zone in which flows and pressures into the area are measured continually 24/7. Analysis from the DMAs establishes where the water network is leaking more, and where the biggest volumetric reductions can be achieved.

Super DMAs

Squads of leakage control engineers sweep the DMAs across the area, checking valves and fittings and using specialist sounding equipment to pinpoint the locations of leaks and bursts.

In the Tweed area, Scottish Water has 350-400 DMAs. In Edinburgh, there are five “super DMAs”.

To tackle leakage in the Scottish capital, the company has been trialling leak monitoring and detection equipment from SebaKMT comprising P1 correlators, loggers and locators.

The Sebalog radio loggers, which feature an in-built aerial, measure and analyse noise levels and frequencies to help detect leaks during pre-location. Their measuring timeframes and reading points are pre-programmed and then deployed. Data from the loggers can be retrieved using the Sebalog Commander reader. The data is analysed, evaluated and documented using the Sebalog software.

SebaKMT’s Correlux P1 correlator is for locating leaks on pipes for potable water. The noise made from water escaping a leak under pressure is recorded by two sensors attached to the pipe amplified and transmitted to the correlator. The Correlux P1 compares both signals and calculates the exact distance to the leak from the signal delay, the sensor distance and the sound velocity

Apart from SebaKMT equipment, the Tweed Leakage Delivery team has also been trialling other manufacturers’ monitoring and detection equipment – Palmer and Halma, for instance. The teams trial the products and provide feedback.

Scott Young, leakage technician supervisor in the Tweed Leakage Delivery team, says the SebaKMT loggers were brought in to cover the five DMAs within Edinburgh because of the location – it has a busy traffic town centre – and the number of properties. With up to 20,000 properties in each DMA, some of the zones have been split and Scottish Water plans to redeploy some loggers to ensure areas and properties not in a DMA are covered.

Young says: “The loggers are being used to detect leaks and any performance issues to see how the [water] network is working. We’re hoping to pre-empt major bursts.”

Scottish Water is also using some loggers to monitor boundary valves.

He says 600 Seba KMT loggers have been deployed in the Edinburgh region, identifying where the leakage hotspots are. The data analysis will also help further reduce the two-week repair cycle to three days.

The loggers are programmed to automatically collect data daily between 2am and 4am when there is very little sound, says Young The correlators are used during the day.

The logger reader plugs into the Toughbook so that the engineer can “log on”, identify the logger and enable it to transmit the data it has collected.

Closer look

Data is collected from the loggers usually by the two-man squads doing “a drive-by”, although there can be places where the team have to get out usually because the logger signal is not being detected — amazingly, loggers have been missing. One team member drives while the other uses a Panasonic Toughbook.

However, collecting data from vehicles is not all plain sailing. The seals located in roads get clogged up from dirt caused by traffic, making it difficult to get drive-by readings so the patrol have to risk their lives from oncoming traffic to get a closer look.

If the logger has detected a leak the squad can call out engineers immediately, depending on how serious it is. If the leak is found to be under a house, for instance. all Scottish Water can do is serve legal notice to the homeowner to get the problem fixed. Scottish Water adopts a different approach for similar situations concerning business properties. It informs the business about the leak and offers to repair it.

If Young could change anything about the logger it would be to have a conical or triangular point on the device. The logger has a thin plastic top that is easily punctured by the probe tool, making it difficult to hear the signal, he says.

The Edinburgh team has also been trying out digital mobile telephony. The GSM (Global System for Mobile communication) boxes collect data from loggers – Young would like three or four loggers signed up to one GSM box and relays that back to the Leakage Delivery team.

One problem encountered that Young has found with these is that the boxes are positioned on lamp-posts and some have been vandalised. Ideally, he would like the boxes to be installed in “hard to get at places” and linked to a phone, although this could create a problem as they might not be able to pick up a signal.

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