George Leslie Ltd

Key Facts

Marine Works

Cowal Cluster Wastewater Project

The Cowal Cluster Scheme, consisted of the upgrading of the existing wastewater treatment works and marine outfalls, in order to comply with the EU Urban Waste Water Treatment Directive (UWWTD), and encompassed the three communities of Ardenfield, Carrick Castle and Colintraive, on the Cowal Peninsula of Argyll.

The main construction elements included the:

  • Removal of four existing sea outfalls
  • Construction of four new sea outfalls, with an average length of 225m.
  • Decommissioning of four existing septic tanks
  • Construction of three new septic tanks including M&E control, monitoring and telemetry

The improved treatment, which included the installation of new septic tanks and long sea outfalls, was required as part of the UWWTD to improve the quality of the existing continuous discharges.

Particular issues with this project included the remote locations, the impact of working within small coastal communities and the Planning conditions attached to the new installations and throughout the project, particular attention was paid to the management of the various third-party stakeholder issues.

The project development, detailed design, site construction and commissioning was undertaken by the Biwater Leslie Joint-Venture as a Delivery Partner with Scottish Water Solutions.

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