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Your sinkhole questions answered

  1. 02 December 2015
  2. By Rosie Rogers

We have invited PropertyDetective to discuss an important topic on the blog today - sinkholes. Those near St Albans and in other areas around the country understand the shock and fear which can be associated with the threat of a sinkhole.

At Property Detective our mission is to provide a complete and transparent picture of a local area for someone who is moving home, so this topic is of specific interest to us. When news spread of the St. Albans sinkhole we reached out to the company Terrafirma Mine Searches to get a better picture of the sinkhole threat that exists in the UK. The answers were a bit alarming, but we felt we needed to explore it further and host a Twitter chat to discuss the topic with the public.  Since the chat we’ve pulled together the following facts about sinkholes in an effort to inform and educate on the topic. 

What are the different types of Sinkholes and what causes them?

When it comes to sinkholes this answer isn’t a short one. There are many different types of natural and man-made sinkholes, however we have focused on sinkholes related to mineral extraction, a phenomenon that has recently becoming scarily more common across the UK.
Mining and mineral extraction touches every corner of every county in the UK, with mine shafts, shallow underground workings and surface quarries littering the landscape. There are a growing number of shaft and mine working collapses each year and in areas of the country that were never associated, at least to the unaware, with mining. Upon cessation of the mines, many shafts were capped with wood, backfilled with mine waste, rubble and soil and abandoned. Over the past two centuries, the wood capping shafts and shallow workings will have deteriorated, until, due to complete degradation, it inevitability collapses, causing devastating damage to the surface above. As well as shafts; shallow underground mine workings, drainage tunnels (adits), irregularly backfilled quarries and buried opencast pits can all pose a significant risk to ground stability and therefore to property and land.

Where in the UK can mining related sinkholes occur? How can I know if I am at risk?

Terrafirma has mapped mineral extraction of over 35 different minerals throughout the UK and can now, using its revolutionary new three-tier search system, identify and assess the risk to property and land from past, present and planned mining and mineral extraction. Mineral extraction related ground subsidence can occur across the UK and with the threat becoming more visible, such as recently in St Albans, it is important that we can provide you with expert information and solutions. 
Aside from the well-known mining hub of West Devon and Cornwall, West Midlands and the Coal Mining areas, there are numerous other regions where historic mineral extraction has left a hidden legacy lost beneath our feet. To name just a few areas, South East England, in particular, South East London, has seen numerous chalk, silica sand, limestone and clay mines lost beneath growing residential developments; Northamptonshire and Lincolnshire are riddled with long forgotten Iron Mines; North Wales was once the slate and lead mining capital of the world and much of North Somerset and Gloucestershire is potentially at risk from little know but once rich mining industries for; Celestine, Ochre, Calamine, Bath/Free stone and Fireclay. As for Fracking; this is an inevitable issue that will impact much of England and Wales, however the actual risk is very low; Terrafirma's search reports assess the risk from expert geologists perspective and provide you with professional peace of mind.

What advice would you give to a home owner or buyer?  

First of all, it would be beneficial to identify whether your property is within a risk zone from past, present and planned mineral extraction. In the event of a potential risk, we advise you to seek out further information from the expert team at Terrafirma, who can advise you on the next best course of action. 
If you are in the process of moving home, you can recommend your conveyancing solicitor to contact Terrafirma for our mineral extraction search report before purchasing a property or land.
If you already live in a potential risk area, it would be beneficial to seek out a local surveyor to assess your property’s risks. There are ways to prevent a potential sinkhole and your surveyor should be able to offer you these options as well. Remember, ground collapse and sinkholes associated with mining and mineral extraction are a rare phenomenon, however they are becoming more frequent and now is time to learn more about the ground beneath your potential dream home, as we always say researching prior to buying is always key!


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