On 12 February 2013 the BGS Landslide Response Team received reports of a landslide affecting the railway near Hatfield and Stainforth Station, near Doncaster in South Yorkshire.
The landslide occurred in a spoil heap at Hatfield Main Colliery and distorted a large section of train line along the Doncaster to Goole and Doncaster to Scunthorpe lines.
Train services in the region have been significantly affected and this section of the line is currently closed.
The landslide was first reported in the media on 12 February when NetworkRail issued a statement:
'We have been carefully monitoring the track near Hatfield colliery at Stainforth since Saturday afternoon (9 Feb) when a train driver reported a "rough ride". Unfortunately conditions have deteriorated and it is no longer possible to run services through the area. We anticipate that there will be disruption to services between Doncaster and Goole and Doncaster and Scunthorpe for some time.'
Since then, the media has reported that the landslide has continued movement and it is likely that this will the case for some time.
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The geology underlying the spoil heap is classed as alluvium, which is usually soft to firm unconsolidated, compressible silty clay with layers of sand and gravel, and has been deposited by rivers. Local thickness of these deposits varies between 5 and 10 m. These deposits rest on the Nottingham Castle Sandstone Formation (early Triassic).
Current land use includes large areas of artificial ground in the form of colliery spoil. The sequence of Ordnance Survey (OS) historical maps (1854, 1893, 1907, 1933, 1948 and present land use) shows that previous land use, that was dominated by agriculture before the 1930s.
The 1933 OS map shows an increase in industrial activity, including the construction of extensive railway sidings.
The historical OS maps also provide a further indication of the nature of the alluvial deposits.
The existence of land drains and borrow pits near a tile kiln just south of the site suggest locally high clay contents in these alluvial deposits.
It will take considerable investigation to determine the exact mechanisms leading to this slope failure. We will report on these outcomes as they become available. As the recent events of 2012 and early 2013 have shown, there is a close relationship between rainfall and the occurrence of landslides. Smaller landslides often occur during, or shortly after periods of heavy rainfall. Large landslides often require much more time and successions of rainfall events before these become unstable as water can take considerable time to percolate to greater depths. It is therefore possible that, even if the weather improves from now on, we might still see larger landslides occurring as a consequence of the long, wet period we have been experiencing.
The morphology of the slope strongly suggests a rotational mode of failure. Along the crown of the slope extensive tension cracks are now observed that are gradually growing in size as the landslide progresses its downward movement. A slope like this can be viewed as a large pendulum that slowly moves into a more stable position. However, this can take quite some time. Particularly as there is still considerable surface water visible at the top of the slope. This water will slowly seep through the tension crack (shown as red dashed lines) into the landslide and will continue to facilitate movement.
The white arrow indicates the main direction of movement of the landslide.The position of the railway line is at the toe of the landslide — the exit point of the main shear surface is right in the centre of the railway line (white dashed line), explaining the uplift of the railway line. Continuing movement of the landslide has caused further displacement of the track.
The BGS has recently added a 'Slope Failure' category to its landslide type in the National Landslide Database.
This allows us to capture the recent increase in landslides occurring on artificial ground, something that is clearly of interest to the public and infrastructure asset managers.