Blackburn Meadows Waste Water Treatment Works
Waste Water Treatment Flocculation Tank Scraper Bridge Design.
Blackburn Meadows wastewater treatment plant (WWTP) is located in the city of Sheffield in South Yorkshire, UK.
The WWTP was constructed on a 78 acre site which falls under the jurisdiction of Yorkshire Water. The site serves some 800,000 inhabitants of the cities of Sheffield and Rotherham.
The plant was upgraded by a joint venture (JV) of AECOM and Galliford Try with a contract value of £49m. The scheme expanded the plant’s capacity to serve up to 830,000 people.
Plant owner Yorkshire Water awarded the two contracts to the JV in April 2012. Worth in excess of £30m, the first enables the treatment plant to meet the requirements of the EU Freshwater Fish Directive (FDD).
Worth around £19m, the second contract enables the plant to treat 21,000t of sludge annually, with integrated thickening and dewatering processes. The upgrades were completed in April 2016.
During the upgrades, it was noted the scraper bridges within the sites flocculation tanks were suffering damage during prolonged operation. SGL were appointed to carry out structural inspections of the tanks to determine the probable cause of failure.
SGL found the scraper bridges, which were constructed of long span steel truss sections were twisting under load, resulting in excessive deflection of the scraper arms and inadequate operation of the flocculation tanks. On closer inspection, it was found the scraper bridges had undergone permeant plastic deformation and repair was none-viable.
SGL provided a new design for the 40m long scraper bridges which incorporated high torsional stiffness to resist the torsional stresses induced under load and minimise deflection of the scraper arms to ensure their correct and proper operation throughout their design life.
By working closely with Yorkshire Water and the steelwork fabricator, the new scraper bridges were successfully installed and began operating successfully.