Scottish Water is starting work today on a major investment in its waste water infrastructure in Paisley, which will improve the water quality and natural environment in two local rivers.

The £17 million project will include the construction of a one mile long sewer, or waste water tunnel, under the streets of Paisley and the installation of Combined Sewer Overflows (CSOs) in the town centre. The new stretch of sewer will have a diameter of up to 1.5 metres and will be installed at depths of between 4m and 20m.

It will be installed using the ‘closed face’ method, with pipe-jacking used to install the pipes behind a Microtunnel Boring Machine (MTBM).  A total of 15 shafts will be installed along the sewer route, with the MTBM tunnelling between them.

The water company said the measures will substantially reduce the frequency of spills from the sewer network into the Espedair Burn and White Cart Water in storm conditions.

The investment, which is the biggest of its kind Scottish Water has ever made in Renfrewshire, is part of the company’s £250 million, five-year programme of work, launched in 2013, to improve river water quality and the natural environment and tackle flooding across the Greater Glasgow area.

The overall investment, which includes the Shieldhall Tunnel in south west Glasgow, is the biggest in the Greater Glasgow area’s waste water infrastructure in more than a century.

The Greater Glasgow area investment follows years of collaboration and studies by the Metropolitan Glasgow Strategic Drainage Partnership (MGSDP), whose partners include Scottish Water, the Scottish Environment Protection Agency (SEPA), Glasgow City Council, Renfrewshire Council and Scottish Canals.

The project in Paisley, which is expected to take two years to complete, will improve river water quality in the two watercourses and, in turn, the River Clyde.

The new infrastructure will fundamentally alter the performance of the drainage catchment in Paisley and retain a lot more of the storm flows in the sewer network, which ultimately go to the Laigh Park Waste Water Treatment Works, meaning storm spills to the White Cart Water will also be substantially reduced.

Contractors Amey, are carrying out the work for Scottish Water.