George Leslie Ltd

Key Facts

  • Client: Scottish Water
  • Engineer: Jacobs
  • Conditions of contract: NEC 3 Option A
  • Contract value: £5.06m
  • Duration of works: August 2012 - July 2013

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Water Supply & Pipeline Work, Water Treatment Works

Katrine Aqueduct Refurbishment

Inaugurated in 1859 by Queen Victoria, the 42km long original Katrine Aqueduct has the capacity to deliver 50mgd of raw water by gravity flow, from Loch Katrine in the Trossachs to storage reservoirs at Mugdock on the outskirts of Glasgow and is the primary source of water serving a large part of the Greater Glasgow conurbation.

The aqueduct has a significant number of structures which include 40km of twin tunnels, substantial pipe-bridges, a large intake structure, siphon pipelines crossing valleys, cross-over chambers, together with control valve houses and this project involved extensive structural refurbishment and repairs to maintain security of supply.

  • Pipe-bridgework: encompassed steelwork replacement, enhanced steelwork support, crack sealing, abutment masonry repairs, and comprehensive grit blasting and application of a new full-protection coating system across sixteen structures, the largest of which was the 200m long aqueduct bridge in the Duchray Valley which comprises a rectangular cast iron trough 2.4m x 2m, some 16 m above ground level.
  • Tunnel repairs: masonry and concrete repairs and re-lining over a 4km section of 2.4m diam tunnel
  • Valve and Valve-House repairs: this work included refurbishment of thirty three large diameter valves and penstocks undertaken wherever possible without recourse to mains shut-down or alternatively rescheduled to run concurrently with other work under planned isolations. Repairs and access improvement were also carried out in the Valve Houses.

Other work included scour repairs and protection to an undermined pipe-bridge abutment carrying three 42″ mains over the Endrick Water with extensive special protective measures to prevent silting of this important watercourse during the mid-river construction work, and slip-lining a 27m length of corroded 42″ main.

With over thirty historic Listed Structures on the aqueduct, the essential repair programme required extensive consultation and approvals throughout.

Additionally, a significant number of properties received a raw water supply from the aqueduct and during planned shutdowns alternative supply arrangements had to be put in place.


News updates


The overall project involves the off-site fabrication and installation of a new linkspan structure at Oban Ferry Terminal for client Caledonian Maritime Assets Ltd (CMal).

12th February 2019

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GL return to the Sound of Kerrera

GL making a return visit to the Sound of Kerrera off Oban, to undertake substantial repairs to the breakwater which suffered collision damage following an altercation with a workboat earlier this year.

14th December 2018

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Polmadie Bridge official opening……..

Michael Matheson MSP and Cabinet Secretary for Transport, Infrastructure and Connectivity covered all his portfolios at the official opening of the new Polmadie Footbridge giving pedestrian and cycle transport access,

18th September 2018

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George Leslie Ltd, Blackbyres Road, Barrhead, Glasgow, G78 1DU  |  |  +44 (0)141 881 9131