Dreadnought Storm Drain After Rain, Bristol.

(HEADS UP: Do NOT attempt this, these systems can be unpredictable and extremely dangerous. I know this drain quite well and river levels / rain severity was checked and closely monitored prior to entry, with someone waiting aboveground the entire time.) A brief look at the Dreadnought Storm Drain in Bristol after moderate rain. Dreadnought, AKA the Malago Stormwater Interceptor, is a large 2 mile long concrete drain built around 1974. It transports the flows of the Pigeonhouse Stream and the River Malago underground before outfalling into the River Avon.