Clean Water - The Professional Engineer's Contribution To Health
Glasgow Water Then And Now
It is not well appreciated that, by providing water of drinking quality and safely removing waste water, professional engineers' contribution to the health of the people of the world may exceed in importance that of medical doctors. In the city of Glasgow during the first half of the nineteenth century there were major cholera epidemics due to polluted drinking water with 32,00 deaths in 1831 and 62,000 in 1848.
In 1856 an ambitious scheme was commissioned by the Corporation to bring very high quality water from Loch Katrine to the City. This proved to be a landmark achievement of Victorian Engineering. But the delivery of quality drinking water is an ongoing activity. The design and construction of the new Loch Katrine water treatment works being installed at Mugdock is a good example of the very different style of twenty first century engineering.
In 1853 Glasgow Corporation appointed John Frederick Bateman as the Engineer responsible for the design and the construction of the Loch Katrine Works. He had full control of the design and construction for the scheme. The aqueduct from Loch Katrine to the service reservoir at Mugdock near Milngavie is 42 kilometres long with a fall of only about 6.6 metres over that distance i.e. a fall of just over 150 mm (of the order of the span of an outstretched hand) per kilometre. Transmission is all by gravity with no pumping although the gradient is not even. The water is transferred through sections of tunnel, cast iron pipes and syphons. The specification and workmanship was of the highest order. If you walk along the track where sections of the aqueduct are visible you can see how well the bridge and wall structures have survived to be still in excellent condition after 150 years of incident free operation due to regular maintenance.
Initially only minimal water treatment was applied to the Loch Katrine water to bring it up to the standard required at the time but these standards have developed to a point where a major water treatment plant is now needed.
In September 2000 the former West of Scotland Water Authority, appointed the lead contractor, MJ Gleeson to manage the design and construction of the new Loch Katrine Water Works. For the design of the original works John Bateman would have had assistants - but not many. The design of the new treatment works involved over 100 technical staff from 25 different disciplines. The process used in engineering design involves the initial consideration of options. Broad areas to be considered for the New Loch Katrine works included: the type of treatment process to be used, the site of the works and the site of the new reservoir. Criteria to be considered in the choice included cost, risk, reliability, sustainability, public access and amenity and environmental impact. 6000 possible options were considered with 17 potential development areas looked at in great detail. This part of the design took place over an 18-month period. Disciplines involved included: civil engineering, chemical engineering, mechanical engineering, electrical engineering, environmental consultants, cost consultants etc.
A decision was made to use what is called 'direct filtration' as the main treatment process. This has two distinct elements - the conditioning phase in which chemical are added to the raw water and the filtration stage where the conditioned water is passed through an anthracite filter bed.
There is a need for storage of treated water which is being provided by large covered concrete tanks with a total capacity of 160 Ml. These tanks allows fluctuations in demand to be smoothed out so as to allow optimal treatment conditions.
The treatment works were commissioned on 6 October 2007 at a cost of £120m. By comparison the cost of the original works was less than £2m.
It may not be realistic to compare the nineteenth century and the modern works because they do not do the same thing. The original works was for transporting water form Loch Katrine to Glasgow with very little in the way of treatment. The fundamental function of the new works is treatment. One could say that that the construction of the original works was challenging because of the lack of technology. The new works are challenging because of the complexity of the technology. Both are excellent examples of outstanding professional engineering.