Optimus Prime is a large culvert that takes the River Irk underground for it's final stretch before the outfall into the Irwell. I met up with Nckt and Jim Gillette to have a look.

When I saw RCP through the grated infall I thought this would be another of Bury's boring prefab systems. I have to say I was pleasantly surprised when after a short length the concrete turned to stone and joined another culvert.

The drain starts off in brick around 7ft tall. This then alternates between short stretches of RCP where repairs have been made, before opening up into a large egg shaped section.

Hidden on the riverbank of the Irwell the outfall looks like a portal into a time gone by.

This drain is in one of Manchester's surrounding northern towns and was a bit of a stooper, 3ft RCP being king here.

A concrete CSO overflow built into a hillside near Bolton.

Lock Stock is a Victorian/Interwar period brick overflow system that has two large overflow chambers and a 9ft overflow culvert.