Erskine Bridge project
Completed in 2019, SGN's Erskine Bridge project involved the replacement of twin high pressure gas pipeline carried on the underside of Erskine Bridge. The new 450mm pipeline installation used a combination of trenchless methods, including a 1km HDD beneath the River Clyde, linked by trenched installations.
Riggall and Associates were involved from the initial route selection in 2014 through ground investigation, planning and design, and construction phases, with the project being completed in 2019. Riggall & Associates also undertook the tasks required for Transport Scotland approvals in accordance with HD 28/08, including the Statement of Intent (SOI), Ground Investigation Report (GIR). and Geotechnical Design Reports (GDR).
The HDD crossing was technically complex with numerous key risks, including the following:
- the potential for unexploded WWII ordnance
- avoiding disturbance to the piled foundations for Erskine Bridge
- close proximity (<15m) of residences, a church, and a listed building
- drilling beneath an A road
- a 2.4m wide pinch-point in the easement at 100m from entry
- crossing beneath a lock on the Forth and Clyde canal, further complicated by an aqueduct located underneath the locks
- environmental considerations with the HDD passing beneath the the Saltings Nature reserve, Boden Boo Community Woodland and Mar Hall golf course
- crossing beneath the River Clyde
- difficult ground conditions; gravels, cobble and boulder, swelling clay, and boulder clay on the north side, changing to basalt rock on the south side
- the presence of artesian groundwater
- Challenges caused by the topography and restricted areas available for construction compounds and stringing alignments
The HDD used hydrofracture modelling, real time annular pressure monitoring, and settlement monitoring, to mitigate the risks for adjacent structures and environmentally sensitive areas. The expertise and proactive approach taken by LMR Drilling (UK) in managing the ground conditions was also a key part of the completion of the HDD.
SGN's thorough planning and management of the project through the various phases ensured that this challenging project was completed successfully. The project was shortlisted for the Project Management Institute 2019 Project of the Year Award [Large Private Enterprise].
The link below to SGN's video of the project provides further insight into the project as a whole: SGN ERSKINE BRIDGE VIDEO