Developers can no longer rely on coal mining searches as a result of recent guidance from the Coal Authority.
Given a recent subsidence case in the North-East of England, Isabel Alderton-Sell of DMH Stallard’s Property Development Team looks at a recent call by the Coal Authority to ensure that coal mining legacy issues are not overlooked.
The Coal Authority was contacted by the National House Building Council in July 2016 after extensive subsidence at a housing development in North Tyneside came to their attention. A subsidence zone of around 150 metres x 70 metres affected 35 properties on a housing estate.
Ground investigations subsequently carried out by the Coal Authority revealed historic coal mine workings which were not recorded on the historical mining plans held. The plans actually showed an area of solid coal when, in fact, the Coal Authority’s ground survey showed extraction rates in this area at over 70%, which led to the subsidence.
In light of this subsidence event, the Coal Authority has issued the following guidance:
- Caution must be adopted in assuming that the absence of a record of coal mining means the absence of mining. The historic plans might not give a true representation of the coal workings on the ground.
- Both desk based and ground investigations are necessary to confirm:
- potential for unrecorded shallow workings
- accuracy of the shallow coal old working plans
- competence of the strata overlying the coal
- potential effects of groundwater, including assessment of recovering levels post mining which are still taking place today
- appropriate ground investigations should always be undertaken to confirm site specific conditions, and local geology also needs to be considered
For more information on this or similar issues, please contact Isabel Alderton-Sell in the Property Development team.