The replacement WTW at Milngavie will serve 700,000 Glaswegians. We look at the progress of Scottish Water's £120M job, known as the Katrine Project
It’s costing Scottish Water (SW) £120M and will eventually serve some 700,000 customers in the Greater Glasgow area – the replacement WTW at Milngavie, or as it is known, the Katrine Project, is well advanced and ahead of target.
The project’s progress delighted SW’s former chairman Professor Alan Alexander, who visited the site shortly before his sudden resignation. Commenting on how the giant engineering jigsaw was coming together, Professor Alexander said: “Although one of the biggest challenges Scottish Water has ever faced, this flagship development has progressed extremely well indeed. The project team has overcome numerous technical and other obstacles to design and establish the necessary facilities, all of which have required innovation and a tremendous amount of co-operation.
“Naturally, everyone is delighted that the project is not only on schedule for completion according to plan, but will deliver a higher-quality supply to a huge section of the distribution network much earlier than orginally anticipated.”
Glaswegians were promised even higher quality standards of their drinking water with the advent of the Katrine Project. He added: “As a result of the latest technology incorporated in the filtration process at the (new) plant, they will get quality of the highest standards directed to homes and businesses.”
Areas such as Hillhead, Hyndland, Partick, Yoker and Glasgow’s city centre have been earmarked for upgraded supplies due to the earlier-than-expected completion of the giant reservoir and significant progress in the overall construction work.
Katrine Water project manager Gus Watt said: “As a result of the progress made by our principal construction partner, MJ Gleeson, we were able to re-examine the entire sequence of the building programme and identify areas that could benefit by further concentrated attention. Therefore we were able to focus on specific aspects of construction, which will allow the earlier delivery to some customers.”
Both the Mugdock and Craigmaddie reservoirs at Milngavie currently feed into the existing WTWs, which where built more than 150 years ago. By 2007, water from them will be supplied to the new WTW under construction at nearby Barrachan.
Already, one of the huge tunnels which draws raw water from Mugdock Reservoir for treatment is now complete. And tunnelling operations at adjacent Craigmaddie are under way and due for completion by the end of summer 2006. This will complete one of the most challenging aspects of the three-year Katrine programme. Eventually, both tunnels will be linked to a complex formation of intake pipework and a pumping station to ensure that sufficient quantities of water are available at all times for processing.
During the tunnelling work, engineers had to blast and drill a 15m diameter shaft down through 30m of rock, sandstone and clay before changing direction horizontally for 150m to pierce the Mugdock embankment below the water line.
Glasgow is currently supplied with some 240Ml/d and supplies have remained unaffected during the Katrine Water Project work. Mark Allan, contract manager for MJ Gleeson Group, the main contractors said: “Each of the two tunnels required has an intake structure built within the existing reservoirs. The embankment and surrounding infrastructure are all of listed building status. Therefore close liaison between client, contractor, sub-contractor and designers was essential to meet the challenges of delivering this technically difficult element of the work within such demanding constraints.” When operating, the new pumping station’s four massive pumps will take water from both reservoirs and deliver it to the new treatment plant some 500m away via a 1,400mm diameter steel pipe.
Professor Alexander concluded: “From the outset, it was appreciated that developing the new works within the residential and highly sensitive Milngavie area would require careful planning, co-ordination and consultation with the local community. One of our key objectives was to minimise the impact of construction activities in the local area.”
Around 40% of the treatment plant will be underground and purposely designed to blend with the curve of a local hillside and the surrounding tree line. Its concrete roof will be covered with grass. Raw water from Loch Katrine, about 42km away, will still be delivered by gravity and be treated through direct filtration – chosen after a year-long pilot plant trial at Milngavie.
Replacing the aging Victorian works will ensure that water supplies to Glasgow are free from Cryptosporidium, which forced customers in the city to boil their tap water in 2002.