This project was to undertake various flood alleviation works which included the construction of a large flood attenuation basin, piled reinforced concrete retaining walls, river bank strengthening, and culvert up-sizing together with extensive channel realignment over a 1km length of the Knowle Burn through predominantly urbanised and residential areas in the centre of Dumbarton.
The high-profile attenuation basin works, adjacent to the main A82 trunk road in front of West Dunbartonshire Council offices in Garshake Road, involved the excavation of 22,000m3 of unsuitable material and geotextile protection of the formation prior to shaping and contouring the basin area to the final profile. The southern basin boundary was protected by a masonry-clad, 700m long reinforced concrete retaining wall on piled foundations. The finished basin surface was protected with coir blanketing to minimise soil erosion and encourage early vegetation growth.
A new 1.2m x 600mm box culvert flood bypass channel was installed along a 300m length of Round Riding Road, involving the prior diversion of utilities and extensive, road-closure traffic management.
Elsewhere along the greater length of the works, the river reach was widened and regraded with gabion and concrete walls constructed to provide near-vertical river banks within the heavily constrained and tight confines of adjacent back gardens on either side.
At the downstream end of the works, a newly aligned channel was formed, with a series of step features formed with cobbles and boulders creating a step-pool feature.
Throughout the duration of the works, close liaison was maintained with local residents and statutory bodies to minimise any inconvenience in undertaking much of the potentially disruptive and intrusive work.
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
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
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