In amongst all the veritable ‘flood’ of comments upon the sewage screw-pump failure at the Seafield Treatment works in Scotland, a few reasoned and temperate, the vast majority both uninformed and typical of the extremely low levels of knowledge of basic civil engineering processes; almost all missed the one basic action which was perfectly demonstrated by the increased flow of sewage into the Forth Estuary. This action is of course part of the established practice, extant in all areas of the developed world where civilised societies have built water treatment and sewage plants for the continued health of their population; in that when an ‘Event’ occurs, whether through an equipment failure or a sudden downpour threatens to overcome the existing works and storm systems, the ’emergency flow’ will always be towards open water! If stations had to be designed and built to cope and contain all eventualities, they would need to rise in size, cost and complexity by a factor of about thirty. One comment asking why there weren’t two archimedes screw-pumps in play at Seafield is a valid one, and that can only be answered by those who chose, finalised and accepted the design. The screw-pump in question raises the sewage, which flows into the works at a very low level, up a height of some ten metres, so that gravity runs virtually all the process after the pumphouse!
Where I personally would take issue with Scottish Water is in their choice of Thames Water to help build and run their plant, which was upgraded in a PFI set in 1999. Thames, from the moment of it’s inception as a privatised Company, has only been interested in one thing, increase of ‘Shareholder value’ and everything is subordinate to that purpose! During my own involvement with Thames, sometime as a direct contractor and sometime whilst working for consultants, the rush towards automation, and hence de-manning, was foremost in the minds of the original directors, almost all of whom have moved on once their damaging work was done. The lists of maintenance and breakdown tasks which grew exponentially was legendary within the industry, and when Thames was the body part of the old Metropolitan Water Board, such lists would have been grounds for dismissal of senior staff and management; nowadays this conduct is rewarded with promotion and bonuses!
The old adage of ‘you get exactly what you pay for’ does not ‘sync’ when one deals with Thames Water, and Scottish Water, in my own personal view, made a bad bargain for their fellow Scots when they signed up with this rapacious conglomerate!