St Alban's Sinkhole: Part 2 - Terrafirma explore the possible causes of the recent St Albans sinkhole for a recent @BBC3CR radio interview…
Explore the legacy the UK's once great coal mining industry has left on property and land in Terrafirma's new Infographic. With almost a third of all buildings in the UK underlain by coal mines, over 9000 recorded hazards and a new mining subsidence claim made every week of the year…
Exploring the themes behind Sinkholes in the UK
At Terrafirma, understanding the ground is what we do best: Our CEO Tom Backhouse was recently asked to feature in Channel 5’s documentary Sinkholes to provide an expert insight into the roots behind their cause. Inevitably then, when high profile sinkholes such as those at Fontmell Close, in St Albans or in Wednesbury, causing up to six million pounds of damage and evacuating families from their homes, we ask ourselves “can sinkholes be predicted?”.
Over the last few months and years, the experts at Terrafirma have meticulously observed, understood and recorded each sinkhole as they form. Now, armed with this information, Terrafirma is proud to present a new dataset and report feature; ‘SinkholeAlert’, allowing our team to examine the common themes behind these hidden dangers.
The formation of a ‘sinkhole’ beneath a property in Wednesbury, West Midlands has received abundant coverage from the mainstream media during the last week. At Terrafirma, we have been looking into this event to try and understand more about its cause and wider context.
The age of solely relying on data in environmental risk assessment is over, with a visible shift in the way professionals perceive risks such as contaminated land and flood. Where historically data alone was enough to accept due diligence, now both a professional opinion and interpretative data modelling is a standard in assessing and managing these environmental hazards.
However, despite the significant annual financial expenditure (between 4 and 15% of all Buildings Insurance Claims in the past 5 years were attributed to subsidence) and the increasing visibility of the ‘Sinkhole’ phenomena, this shift in due diligence process has not been replicated in assessing the risks the ground pose.
On 29th June 2017, a 6 metre wide and 3 metre deep sinkhole opened in the middle of a busy Liverpool commuter route to the M62, Edge Lane, closing it for several weeks. United Utilities were called to the scene to assess the damage and discovered the sewer 6 metres down was blocked. The area rests upon superficial till rich with clays which are prone to subsidence which in turn can damage subsurface utilities.
A sinkhole has formed during September 2015 on Bull Street, Lower Gornal Dudley, West Midlands. As a physical example of ground subsidence, the Bull Street Sinkhole (BSS) is hardly remarkable; with a diameter of >2ft and a depth of 6-9ft1, the BSS is a relic of historical mine workings, typical of those that form in the regions of the UK with a pronounced mining legacy.
In this instance, the degradation of historic shallow coal workings (the exploitation of coal seams at depths of <30m) triggered subsidence, though subsidence caused by the exploitation of a further 60 resources (tin, lead, copper, iron, sandstone, chalk and limestone just to name a few) is common across the UK.