We are due to make our fourth and final visit to Blackburn and Darwen Wastewater Treatment Works (WwTW) next month. In 2017 United Utilities started work on a four year improvement project at Blackburn and Darwen WwTW, two of their major treatment works. The work is required to meet the new river water quality and bathing water standards and improve the quality of used water that’s returned to the environment.
The first of the three previous three visits this year saw us drill 600m of 125mm HDPE plastic pipe to connect Nabs Head works to Blackburn so that treatment can take place using the improved processes being constructed and installed at the much larger plant. Visit two and three involved 125mm and 180mm pipe installations in and around the plants and visit four will use 180mm pipe bringing the cumulative total up to around 1500m. Both sites are live and operational.
The project has been slightly unusual for us. Following installation and pressure testing of the pipe at depths up to around 6m we have cut into the pipe to fit air valves at high points and washouts at low points. These fittings are required to allow future maintenance of the pipeline. Chambers were then constructed around the fittings to complete the work. Our experienced rig crews also carried out the air valve and washout installation providing them with an interesting alternative to the usual operation of technical and sophisticated drilling rigs.