Scottish Water has completed a key piece of engineering on a £120m water mains improvement project by diverting a river in East Ayrshire to enable the pipe to be installed.
In mid-August contractors working for the utility diverted a short stretch of the Craufurdland Water near Kilmarnock to enable them to install the water main beneath the river bed.
The operation was carried out by Caledonia Water Alliance (CWA) to enable a 60-metre stretch of the permanent riverbed in picturesque countryside near Craufurdland Castle to run dry before they could excavate and install the 900mm steel pipeline in dry conditions while allowing the river, and its inhabitants, to continue flowing downstream relatively uninterrupted.
The work, which took about five days to complete, involved the excavation of a temporary channel which needed to be wide enough and deep enough to carry the volume of water that naturally flows along the watercourse.
The channel was lined with a plastic sheeting to prevent the banks scouring away and to prevent any siltation of the downstream watercourse.
Straw bales and one tonne builders’ bulk bags filled with gravel acted as a barrier to redirect the watercourse in to the new channel that was excavated so that the water flow passed around the working area.
The watercourse was identified as significant and well stocked by the Ayrshire Rivers Trust (ART) who were engaged by Scottish Water to carry out ecology screening of watercourses where the pipeline crosses through them.
CWA liaised with the ART about the timing of when the watercourse could be diverted. No interference with the river bed is allowed between October and May due to spawning fish, such as brown trout and salmon.
A window was identified when a few consecutive dry days were forecast and the ART arrived on site to undertake a fish rescue using electro fishing techniques where an electrical current is passed through a metal rod placed in the water which attracts the fish towards it before the fish are caught in a net and transferred by hand downstream of the diversion and released unharmed back in to the water.
Certain species of fish were measured by ART before being released to allow data on the watercourse to be updated.
Mrs Jane McKenzie, Scottish Water’s communications manager, said: “Scottish Water is working on the latest phase of a its £120m water mains project which will benefit so many people across much of Ayrshire and East Renfrewshire.
“However, as with every project large or small, we are acutely aware of our environmental responsibilities and the diversion of a stretch of the Craufurdland Water during this key phase of the project is a prime example of that.
“We liaised with the Scottish Environment Protection Agency (SEPA) for the formal consent and permission to cross the river and we used a tried and tested method of moving a watercourse temporarily to enable us to install the water main while minimising disruption to the river.
“We are delighted to say the operation was completed successfully, while protecting the fish in the river, and we are now continuing to progress with the pipe installation beyond the river.”
Scottish Water is improving the water supply network by installing more than 30 miles of new water mains to connect the system in Ayrshire with the Greater Glasgow area’s network.
The new and expanded network will enable Scottish Water to provide customers with greater security of supply and to respond more effectively to operational issues such as burst water mains and minimise disruption to customers.
Customers across a large part of Ayrshire currently receive their water from a single source, the Bradan Water Treatment Works, south of Straiton in South Ayrshire.
The water is supplied to customers’ taps via a 34-mile-long trunk water main installed about 50 years ago which runs from the Bradan Water Treatment Works to a point north of Irvine.
The construction of the new strategic water main, which is expected to be completed in 2020, will connect the Bradan water supply network to the network served by the Milngavie and Balmore water treatment works, north of Glasgow.