Sinkholes have replaced Jeremy Corbyn this week as the centre of media attention, following the opening up of a huge sinkhole in St Albans. The appearance of the massive 66ft diameter and 33ft deep hole in a suburban street resulted in several families in the surrounding area being evacuated from their homes during the night.
There are several reasons why a sinkhole may appear, both natural and manmade. Even the construction industry can be responsible for the ground disappearing from beneath our feet. Whilst there is little we can do to prevent naturally occurring sinkholes, many occurrences have actually been caused by construction-related activities such as drilling, mining, excavation, broken water or drain pipes, heavy structures built on soft soil and heavy traffic. Sinkholes can also form when the land surface is changed.
It is difficult to ascertain what exactly caused the sinkhole in St Albans; however the number of sinkholes appearing across Britain has been steadily increasing – probably even since the advent of irrigation. The drying out of the ground below through the process of abstraction or the saturation caused by a burst water pipe have been causing sinkholes for years.
Construction has undoubtedly played a part in the increase, particularly over the last 100 years. By its very nature, the built environment morphs and changes the environment around us; inadvertently redirecting water into weak points underground. These weak points get larger and more unstable until eventually pits form with almost no prior warning, swallowing cars, houses, and sometimes even people.
Sinkholes are dangerous, inconvenient and costly to repair. As you read this, work is currently underway to fix the hole in St. Albans that appeared last week. The hole will be filled with foamed concrete – a slow and expensive process that is expected to take several days. Residents of Fontmell Close, St Albans had to evacuate their homes following the sudden appearance of a gaping 10m deep hole in their street.
According to the Evening Standard, an emergency access road was created for residents to get their cars out via a playing field behind the site, and the reception centre at nearby Batchwood Sports Centre was used to yesterday and today by people wishing to shower or take shelter.
Needless to say, the cost and the upheaval created by the St Albans sinkhole is something we would all do best to avoid. Whilst natural sinkholes are inevitable and cannot be prevented, there are perhaps steps that could be taken by us as an industry to curb the manmade ones. Good practices such as regularly performing maintenance on underground water systems and plumbing, site surveys and creation of adequate drainage can help deter that sinking feeling. It’s like the old proverb says; “a stitch in time saves nine!”