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Scottish Water’s carbon challenge

High rainfall and low population do not make Scottish Water immune from sustainability concerns.

Scotland is rich in water resources compared with other parts of the UK, but that does not mean it is without sustainability challenges. There are some areas where the supply/demand balance is not ideal, and - like England - the population is increasingly migrating towards the more densely populated, drier south and east of the country, away from the wetter north and west.

Like its English and Welsh counterparts, Scottish Water, which is responsible for treatment and supply for the whole of Scotland, must also address the issue of security of supply.
From 2010, Security

of Supply Index (SoSI) scores will be part of the company’s Overall
Performance Assessment by which it is judged by its regulator, the Water Industry Commission for Scotland.

The legislation that allowed the creation of Scottish Water in 2002, included an obligation to adhere to the principles of sustainable development. Surveys indicate that the issue is very important to customers.

"They expect us to show a lead in the whole area of sustainability and climate change mitigation and adaptation," says Scottish Water’s asset management director Geoff Aitkenhead.

In contrast to most English water companies, Scottish Water has managed to keep price rises below inflation over the last regulatory period, and the company’s business plan for the next period (to 2014) also proposes below RPI rises. "Within that our customers want the highest standards and - increasingly - at a lower environmental cost," says Aitkenhead. "That’s a good catalyst in terms of looking at innovation, and it sets a fabulous challenge for future Scottish water engineers."

The company is way ahead of others when it comes to incorporating renewable energy into its operations, and has been measuring the carbon footprint of its operations and embedded carbon in construction activities during the current regulatory period.

"Before we started I was of the view that most of the carbon load would be in our operations," says Aitkenhead. "We are one of the biggest users of energy in Scotland, and there is also a lot of embedded carbon in the chemicals we use.

"But, when we looked at it, we found that the carbon footprint of our capital programme virtually matches our operational input.
"The challenge for designers is to optimise their designs going forward to make assets energy efficient and reduce the use of chemicals," continues Aitkenhead.

"But they also have to look at the designs themselves - for example the amount of carbon embedded in concrete and steel structural members, and balancing the amount of the building that is buried in the ground with visual impact issues."

Two recent projects demonstrate this thinking. In the Western Isles the company has just built a treatment works that uses a natural treatment process rather than typical energy-intensive methods. The "facultative lagoon" method, where wastewater is broken down using aerobic, anaerobic and facultative bacteria (which can grow without oxygen), was chosen because it does not produce a sludge - a major issue on a small island.

At the other end of the scale, construction started last month on a new £80M treatment works at Glencorse in Midlothian. It will supply the Edinburgh area.

"We looked very closely at the sustainability issues," says Aitkenhead. 2We intend to put water turbines into the new water aqueduct that will supply 60% of the plant’s power, and we have done some very innovative work in terms of the architecture, including giving the building a green roof."

He acknowledges that climate change mitigation and adaptation will force designers to think differently about the options available to them, but says: "I hope it is one of the things that will motivate the next generation of engineers."

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