Blairlinnans PSC Bypass

Project Details:

Blairlinnans Bypass Tie works was a high-profile dynamic time barred project. It involved bypassing a 700m section of failing pre stressed concrete 42” pipework. AG Wilson was appointed to complete the two-bypass tie ins.

As this large trunk main was supplying water to a large catchment, the pre tested back feeds available were supplying 10 litres per second less than the demand at peak times, this in turn left the Scottish water network team a reservoir with 12days of storage this was proven prior to shut down.

Prior to our works commencing, a rigorous methodology was prepared to tie in with the project constraints milestones and practicalities. This included working closely with the Scottish water Network team to determine the duration of time this trunk main could be shutdown. Two programmes were compiled, one for preparatory works and another for shutdown works.

Works in preparation to the shutdown involved the installation of a significant cofferdam around each of the connection points, further temporary works had to be installed around the pre-stressed concrete pipe to mitigate any disturbance of the ground surrounding these pipes which had been highlighted as fragile structures. AG Wilson developed a strategy to install large trench boxes which supported the PSC pipe whilst the surrounding area was reduced down.

The shutdown programme was developed in line with the SW duration of shutdown detailed tasks subcontractors concrete curing and also resources.

Pre planning exercises on the Blairlinnans Bypass Tie in works enabled us to identify desired goals, reduce risks, meet deadlines and ultimately deliver the project on time and within budget.