The Industrial Emissions Directive (IED) requires water companies to demonstrate that appropriate secondary/tertiary containment measures are in place for their sludge treatment facilities. Northumbrian Water and Mott MacDonald worked collaboratively to develop a comprehensive submission, to the Environment Agency for the Howdon Sludge Treatment Centre (STC), using hydraulic modelling and specialist assessments of tank conditions, site topography and existing drainage pathways. Mott MacDonald Bentley subsequently led on the detailed design and construction of the required secondary containment, which involved bund walls, impermeable areas, isolation valves and drainage grids for a worst-case spill event. This presentation covers the lessons learned from this process, and offers attendees insight into the first STC in the UK to design and build secondary containment as part of the recent IED permit improvement condition implementation plans.