TQ4881 : Cathedral of sewage More precisely, the large rectangular building on the right is home to FOUR triple expansion beam engines. Three are solid rust and one is beautifully restored and can run on steam. The squarer building on the left is a later extension and contained inverted vertical triple expansion steam pumps, long since replaced by diesel engines. There is a long term plan to install an inverted vertical triple expansion steam engine in here. This has been obtained from Victoria water Works, Clifton, Bristol.