Shieldhall Strategic Review
Project Details
Project Description
LBA Role
Project Highlights
Location
Glasgow, UK
Client
Costain Vinci GP JV
Date
2013 – 2018
Project Type
Provision of key tunnelling staff to bid. Construction phase of the works.
Skills
Bid management
Geotechnical Engineering
Engineering Management
CEM
(Contractor’s Engineering Manager)
Value
£130m approx.
Project Description
The Shieldhall Strategic Sewer is a new tunnelled sewer that will relieve the South Side No.1 sewer in Glasgow and provide flow conveyance and storage to improve water quality in the River Clyde and alleviate flooding at key locations. The sewer has a total length of 5435m and was constructed using a precast concrete segmental lining of 4.65m internal diameter and a 5.4m diameter Herrenknecht Mixshield tunnel boring machine. The works were undertaken by a joint venture of Costain and Vinci Grands Projets.
The tunnel was driven through highly variable ground conditions, ranging from soft alluvial deposits to sandstone bedrock. The tunnel route also passes through several areas of former mine workings, which were pre-treated using consolidation grouting techniques prior to the tunnelling works.
The tunnel route included 3 no. undertrack crossings of strategically important railway lines serving Glasgow. The characteristics of these crossings varied in both geometry and geology:
- Paisley Canal UTX: Driven at 70° to the track alignment in very soft alluvial soils with 3.5m cover
- Titwood Rd East UTX: Driven at 90° to the track alignment beneath an overbridge, in mixed face conditions with 4.5m cover
- Crossmyloof UTX: Driven at 20° to the track alignment through pre-grouted coal measures
LBA Role
The LBA team was deployed in two phases: providing support to the CVJV during the bid period from November to December 2013, and during the delivery of the works.
During the construction phase, LBA was engaged throughout the project in a geotechnical engineering capacity. This included managing the mine grouting works, both managerially and technically. Following the mine grouting works, this geotechnical role extended into the tunnelling phase by providing advice for face interventions and by providing technical support to compensation event compilation.
LBA’s geotechnical role also extended to cover the rail interface works. Additional site investigations were required at each crossing and these were planned, procured and managed by the LBA team, ultimately providing confidence to the Network Rail teams.
LBA was also engaged to provide tunnelling engineering management to manage the strategy and the technical approval for the three undertrack crossings. This included managing the interface with the various Network Rail teams, planning and securing additional surveys required for the assurance process and the planning of the disruptive possession in accordance with the Network Rail DWWP process. Risk workshops were chaired to gain a common understanding of each party’s risks.
Project Highlights
The project included the following highlights:
- Successful bid for the tunnelling works.
- Successful completion of the mine grouting works along the route of the tunnel.
- Successful negotiation with Network Rail to undertake the three railway crossings and the subsequent undertaking of the crossings with no adverse impacts to the railway or engineering over-runs.
- Working on the biggest waste water tunnel in Scotland, with the completed tunnelling works reported on by the BBC and hailed by the Scottish Environment Secretary as an “extraordinary feat of engineering which lies hidden deep beneath the city”.
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