Guidance

North East England mine water block factsheets

Published 14 November 2018

1. Acomb mine water block factsheet

1.1 Description of mine water block

The Acomb mine water block is isolated from the main coalfield and is centralised around the village of Acomb, extending up to Barns Wood in the north to Target Wood in the east, Hexham in the south and Nether Warden in the west.

It is considered that the mine water levels in the Acomb mine water block are recovered.

1.2 Contouring methodology

Within the mine water block there is one mine water level monitoring point, a discharge from Acomb Drift. There is also an unmonitored discharge at Birkey Burn. Both the discharges are in the centre of the block.

As there are only two monitoring points within the block, the contours were generated in ArcGIS using the ground elevations at both monitoring points, rounded up to the nearest metre where appropriate, as the controlling outflows. In addition, 11 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the controlling outflow were used in the contouring process.

1.3 Methodology for creating future contours

The Acomb mine water block is controlled by a discharge at Acomb Drift and Birkey Burn and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

1.4 Data issues

There are only 2 discharge points located within the block and hence there is some uncertainty in the interpolated contours. Ground elevations have been used at the monitoring points for the purpose of contouring. There is a possibility that mine water levels are significantly higher than these levels, however this cannot be determined based on the information available.

2. Algernon-Hebburn mine water block factsheet

2.1 Description of mine water block

The Algernon-Hebburn mine water block extends from Shiremoor in the north to Wardley in the south, North Shields in the east and Wallsend in the west.

It is considered that the mine water levels in the Algernon-Hebburn mine water block are rising generally.

The northern extents of the block are well defined with sections of up to 400 metres of no recorded workings. The eastern extents of the block are very well defined with sections of up to 1.1 kilometres of no recorded workings. The southern extents of the block are fairly well defined with up to 100m of no recorded workings. The western extents of the block are poorly defined with possible connections to adjacent blocks.

2.2 Contouring methodology

Within the mine water block there are a total of 6 mine water level monitoring points. There are no current mine water discharges directly associated with the main mine water regime. Four of the mine water level monitoring points are considered to be ‘possible discharges’ and are taken as the approximate ground level. The data comprises a mix of data logger data and manual readings.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods, in this block, mine water levels are considered to be rising and therefore the most recent values, at June 2017, have been used.

Based on historic similarities, the mine water levels at the Shiremoor borehole and Algernon borehole are taken to be the same.

Two dummy control points were added for the purpose of contouring.

2.3 Methodology for creating future contours

The points used to model the future contours include 2 controlling outflows at Wallsend and Hebburn and 8 interpolated points spaced evenly across the block using a gradient of 1 in 114 to the nearest controlling outflow. The gradient has been calculated based on the gradient observed within the block at present.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

2.4 Data issues

The discharges at Wallsend and Hebburn are taken as the approximate surface elevation, rounded up where appropriate to account for any pressure heads required to cause the discharge at the site.

3. Allerdean Mill mine water block factsheet

3.1 Description of mine water block

The Allerdean Mill mine water block is rural and isolated from the main coalfield and extends from Billy Law in the north to Millers Bridge in the east, Felkington in the south and Bleak Ridge in the west.

It is considered that the mine water levels in the Allerdean Mill mine water block are recovered.

3.2 Contouring methodology

Within the Allerdean Mill mine water block there is one mine water level monitoring point which comprises a pipe discharge from Allerdean Mill, at Millers Bridge, on the eastern edge of the block.

As there is only one monitoring point within the block, the contours were generated in ArcGIS using the ground elevation at Allerdean Mill, at Millers Bridge, as the controlling outflow and 9 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the controlling outflow.

3.3 Methodology for creating future contours

The Allerdean Mill mine water block is controlled by a pipe discharge at Allerdean Mill, at Millers Bridge and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

3.4 Data issues

There is only one monitoring point located within the block meaning there is some uncertainty in the interpolated contours. For the purpose of contouring the ground elevation, rounded up to the nearest metre, has been used for the controlling outflow/discharge. There is a possibility that mine water levels are significantly different to this level, however this cannot be determined based on the information available.

4. Bardon Mill mine water block factsheet

4.1 Description of mine water block

The Bardon Mill mine water block is rural and isolated from the main coalfield and extends from Thorngrafton Common in the north to Bardon Mill in the east, Willimoteswick in the south and Hardriding, which is west of Henshaw, in the west.

It is considered that the mine water levels in the Bardon Mill mine water block are recovered.

4.2 Contouring methodology

Within the Bardon Mill mine water block there is one mine water level monitoring point which comprises a discharge from Bardon Mill Old Pumping Borehole in the east of the block.

As there is only one monitoring point within the block, the contours were generated in ArcGIS using the ground elevation at Bardon Mill Old Pumping Borehole as the controlling outflow and 9 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the controlling outflow.

4.3 Methodology for creating future contours

The Bardon Mill mine water block is controlled by a discharge at Bardon Mill Old Pumping Borehole and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

4.4 Data issues

There is only one monitoring point located within the block meaning there is some uncertainty in the interpolated contours. The ground elevation, rounded up to the nearest metre, has been used for the controlling outflow/discharge for the purpose of contouring. There is a possibility that mine water levels are significantly higher than this level, however this cannot be determined based on the information available.

5. Bates mine water block factsheet

5.1 Description of mine water block

The Bates mine water block extends from the River Wansbeck in the north, Whitley Bay in the south and to the west of Cramlington.

The mine water levels are controlled by pumping at Bates Colliery shaft in Blyth. In addition to this there is a gravity discharge at Seaton Burn. Water levels are being lowered to reduce/stop the flows to Seaton Burn.

The mine water block includes offshore workings, the full extent of these are not including in the mine water block for this project.

The western extent of this mine water block is unclear, for the purposes of this project, all the recorded mine workings form this block.

There is a connection between the Bates block and the Central Durham North block and/or Algernon-Hebburn block to the south. At present it is unclear if the southern extents of the Bates block are also controlled by pumping/overflows to the south.

5.2 Contouring methodology

Within the mine water block, there are a total of 10 mine water level monitoring points; 2 historic mine water monitoring points, that are no longer in use and 1 mine water discharge. The data comprises a mix of data logger data and manual readings. Along the coast, the mine water levels show a tidal pressure response of up to approximately 2m.

Due to the nature of the tidal related pressure responses in mine water level drawdown since 2016 and using a mix of logger values and manual readings a different approach to the standard methods has been used.

The contours were generated in ArcGIS and followed the agreed hierarchy of contouring methods. These contours were compared to hand drawn contours. The first contours drawn were means of data from May 2012 to July 2017. However, following discussion and agreement with the Environment Agency, the current mine water contours are based on water levels that are means of data over the time period of January 2013 to June 2016. This also represents a period of elevated mine water levels.

There were no dummy control points added for the contouring purpose.

Although the elevation of the discharge at Seaton Burn is 3.5m above ordnance datum (AOD) a water level of 5m AOD was given to the site. This elevated water level above the surface level is due to a pressure head required to drive the water and cause the discharge.

5.3 Methodology for creating future contours

The points used to model the future contours include 3 controlling outflows, at Seaton Sluice, Crofton Borehole and Bates Shafts and 6 interpolated points spaced evenly across the block, using a gradient of 1 in 500 to the nearest controlling outflow. One dummy control point has also been added to resolve the issue of future contours being lower than current contours in the southeast part of the block.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

The future contours were compared to the current contours to highlight any discrepancies, for example in areas where the current contours are above the future contours. An area in the southeast part of the block required this type of manual intervention. In this instance dummy control points were added to raise the future contours to match the current contours.

5.4 Data issues

The types of water level data collected vary across the mine water block. Some sites have continuous logger data whilst others have manual readings taken every 1 to 2 months. This causes difficultly in comparing some of the statistical values used for normal contouring method, for example the 95th percentile of the maximum.

Some of the monitoring points have tidal pressure related water levels, in some instances this can vary by about 3m. Where there are no data loggers recording high frequency readings, for example every 30 minutes, and just manual readings, this can lead to difficulty in comparing some of the statistical values used for the normal contouring method, for example the 95th percentile of the maximum.

Some of the water levels used for the contouring use trends in data, such as a site’s usual water level in relation to another site’s water level, to determine the values used.

Lack of data and possible links to the Central Durham North blocks resulted in some areas where future contours were below the current contours. This required manual intervention to resolve.

6. Batts mine water block factsheet

6.1 Description of mine water block

The Batts mine water block extends from Whitton Park in the north to Etherley Dene in the east, High Etherley in the south and Morley in the west.

It is considered that mine water levels in the Batts mine water block are recovered.

The northern and western extents of the Batts mine water block are well defined, comprising the edge of the coalfield. The southern and eastern extents of the mine water block is less well defined, with up to approximately 150m of no recorded mine workings in some areas.

6.2 Contouring methodology

Within the mine water block there is one mine water level monitoring point which comprises a discharge from Batts Water Level Dabbleduck Shaft in the east of the block.

As there is only one monitoring point within the block, the contours were generated in ArcGIS using the ground elevation at Batts as the controlling outflow and 5 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the controlling outflow.

6.3 Methodology for creating future contours

The Batts mine water block is controlled by a discharge at Batts and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

6.4 Data issues

There is only one monitoring point located within the block and hence there is some uncertainty in the interpolated contours. The ground elevation, rounded up to the nearest metre, has been used for the controlling outflow/discharge for the purpose of contouring. There is a possibility that mine water levels are significantly higher than this level, however this cannot be determined based on the information available and therefore the approach is considered to be conservative.

7. Blaydon mine water block factsheet

7.1 Description of mine water block

The Blaydon mine water block extends from Blaydon in the north east to Hedley-on-the-Hill in the south west.

It is considered that mine water levels within the Blaydon mine water block are recovered.

The northern and western extents are fairly well defined, with sections of up to approximately 900m of no recorded mine workings. The eastern and southern extents of the block are very well defined with large sections of up to approximately 1.2km of no recorded mine workings.

It is considered that there are some perched mine water levels in the southern half of the block. These have been included in the contouring for conservatism.

7.2 Contouring methodology

Within the mine water block there are 10 mine water level monitoring points. There are 3 discharges directly associated with the main mine water regime: Blaydon Main Hazard Shaft discharge, Freehold Pit discharge and Milkwell Brockwell Drift discharge.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods. The approximate ground levels at the monitoring points have been used for the purpose of contouring.

Three dummy control points were added for the purpose of contouring in the far east of the site so that contours lower than the lowest discharges were not interpolated.

7.3 Methodology for creating future contours

Blaydon is controlled by discharges and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

7.4 Data issues

The ground elevations, rounded up to the nearest metre, have been used for the controlling outflows/discharges for the purpose of contouring. There is a possibility that mine water levels are significantly higher than these levels, however this cannot be determined based on the information available and therefore it is considered that the approach is conservative.

8. Blenkinsopp mine water block factsheet

8.1 Description of mine water block

The Blenkinsopp mine water block is rural and isolated from the main coalfield and extends generally from Blenkinsopp Castle in the north to Haltwhistle Common in the east, Featherstone Common in the south and Eadleystone Rigg in the south.

It is considered that the mine water levels in the Blenkinsopp mine water block are controlled by pumping.

8.2 Contouring methodology

Within the mine water block there is one mine water level monitoring point at Blenkinsopp Smallburn Shaft. There is also a discharge located approximately 400m north outside of the mine water block at Byrons Drift Discharge, which is likely to be connected and hence has been used for the purpose of contouring.

The contours were generated in ArcGIS and followed the agreed hierarchy of contouring methods, and the 95th percentile of maximum values over a 5 year period from 2012 to 2017, were used. Ten dummy control points were added for the purpose of contouring across the block.

8.3 Methodology for creating future contours

The points used to model the future contours include controlling outflows at Blenkinsopp Smallburn Shaft and Byrons Drift Discharge and 10 interpolated points spaced evenly across the block using a gradient of 1 in 500 to the nearest controlling outflow.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

Although the Blenkinsopp Smallburn Shaft discharge location level is known from previous discharge, for the purposes of this project, the shaft ground level has been used. The ground level used is 127m AOD, compared to a decant level of 120.5m AOD on previous occasions.

8.4 Data issues

There are only 2 monitoring points used for the purpose of contouring and hence there is some uncertainty in the interpolated contours.

The data used for the current contours comprises mine water level data, based on a mixture of manual readings and data logger data and ground levels, rounded up where appropriate . The ground elevations, rounded up to the nearest metre, have been used for the controlling outflows/discharges for the purpose of contouring in the future scenario. There is a possibility that mine water levels may rise higher than these levels, however this cannot be determined based on the information available.

9. Bowburn mine water block factsheet

9.1 Description of mine water block

The Bowburn mine water block is rural and isolated from the main coalfield. The Bowburn mine water block extends generally from Moor House Farm, which is north of Bowburn, in the north to Quarrington Hill in the east, East Howle in the south and Hett in the west.

The northern extent of the Bowburn mine water block is well defined with up to approximately 450m of no recorded mine workings. The eastern extent of the mine water block is less well defined, with up to approximately 50m of no recorded mine workings in some places. The southern and western extents of the Bowburn mine water block are fairly well defined with up to approximately 150m of no recorded mine workings.

It is considered that the mine water levels in the Bowburn mine water block are recovered.

9.2 Contouring methodology

There are no monitoring points within the Bowburn mine water block. It is considered that based on International Mining Consultants Ltd plans that the water level within the Bowburn mine water block is either connected or overflowing to an adjacent block, either West of Wear, Sherburn-Houghall or Dawdon-Horden.

Based on International Mining Consultants Ltd plans it is considered that the Bowburn mining block is not connected to the South of Butterknowle Fault block.

The lowest mine entries are likely to be the Tursdale Colliery Shafts, with a ground level of approximately 80 to 85m AOD. This has therefore been used as the controlling outflow, with 8 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the controlling outflow.

Mine water levels are unlikely to rise to this level, however this approach is considered to be conservative.

9.3 Methodology for creating future contours

The Bowburn mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

9.4 Data issues

There are no monitoring points located within the block and hence therefore there is a large margin of uncertainty in the interpolated contours, however it is considered that the approach taken is conservative based on the available background information.

10. Burnhopefield mine water block factsheet

10.1 Description of mine water block

The Burnhopefield, known alternatively as Burnhopfield or Burnopfield, mine water block extends from Whickham in the north to High Park Wood in the east, Tantobie in the south and Rowlands Gill in the west.

It is considered that mine water levels in the Burnhopefield mine water block are recovered.

The northern extents of the block are well defined with up to approximately 300m of no recorded mine workings. The southern extents of the block are very well defined with up to approximately 2.5km of no recorded mine workings. The eastern and western extents of the block are less well defined with up to approximately 150m of no recorded mine workings in some areas.

10.2 Contouring methodology

Within the mine water block there are a total of 10 mine water level points, all of which are recorded mine water discharges.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods. As all of the mine water monitoring points are recorded mine water discharges, the approximate ground levels, rounded up to the nearest metre where appropriate, have been used for each location for the purpose of contouring.

Three dummy control points have been added for the purpose of contouring so that contours below the lowest level discharge would not be incorrectly interpolated.

10.3 Methodology for creating future contours

Burnhopefield is controlled by 10 discharges and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

10.4 Data issues

The ground elevations, rounded up to the nearest metre, have been used for the controlling outflows/discharges for the purpose of contouring. There is a possibility that mine water levels are higher than these levels, however this cannot be determined based on the information available and therefore it is considered that the approach is conservative.

11. Central Durham North mine water block factsheet

11.1 Description of mine water block

The Central Durham North mine water block extends from Newcastle in the north to Birtley in the south.

Currently the mine water levels are controlled by pumping at Kibblesworth shaft, which feeds mine water into the co-treatment scheme at Birtley. Following a pump failure in 2015, the mine water level reached surface at Swalwell in 2016. Since then, mine water pumping has lowered the water level to stop the flows at this discharge.

The northern and northeastern extents of this block are unclear, and there might be a multi-layered mine water regime under parts of Newcastle. Water level drawdown trends at East Holywell, in Bates Block, suggest there is a link between the Central Durham North block and Bates block. The nature of this connection is unclear

The eastern extents of this block are unclear and there may be overflows to or from neighbouring mine water blocks.

The south extents of this block are unclear, but there appears to be limited connectivity between Central Durham North and Central Durham South. Although, it should be noted that pumping patterns in these blocks makes assessment difficult.

The western extents of this block are fairly well defined, especially to the northwest extent, where there is a wide section (>100m, generally >500m) of no recorded mine workings

11.2 Contouring methodology

Within the mine water block, there are a total of 5 mine water level monitoring points. There are no current mine water discharges directly associated with the main mine water regime. However, one discharge did occur in Swalwell in 2016 due to pumping issues.

In addition to the discharge at Swalwell, there have been reports of a discharge at the Garden Festival Site along the River Team and this may be related to elevated mine water levels. This discharge point has been used as a proxy for current and future mine water contours. The data comprises a mix of data logger data and manual readings. There are, or were, 3 discharges with the mine water block. It is unknown if these were due to increased mine water levels, if they are perched mine water, or if they are not mine water related.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods, in this block, the 95th percentile of maximum over a 5 year period between 2012 and 2017. The data includes a period of time with elevated mine water levels and uncontrolled discharges due to insufficient pumping. This would lead the water level data towards the potential future, non-pumped, scenarios. For example, those required for this project.

Although there was a discharge at Swalwell, this was not continuous for the 5 year time period of data used. However, information gathered during the discharge and water levels in the area allows for a comparison of the 95th percentile and Swalwell to be made. Therefore, an interpolated value for Swalwell has been used in the contouring, this value being below the surface level of the discharge point.

There is, or was, also a potential discharge at Garden Festival in the Team Valley. Unfortunately there is limited data about this discharge. For the contouring, this site has not been used.

There were no dummy control points added for the contouring purpose.

11.3 Methodology for creating future contours

The points used to model the future contours include one controlling outflow at Swalwell and 6 interpolated points spaced evenly across the block, using a gradient of 1 in 500 to the nearest controlling outflow.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

The potential discharge sites at Tyneside House and Garden Festival were not controlling outflows in the future contours. The specific details about these 2 sites to control flow are uncertain. Using these 2 additional sites for controlling outflows would lower the levels of the future contours.

11.4 Data issues

The types of water level data collected vary across the mine water block. Some sites have continuous data logger data whilst others have manual readings taken every 1 to 2 months. This can cause difficultly in comparing some of the statistical values used for normal contouring metho, for example the 95th percentile of the maximum. The main variability is due to pumping and the site does not specifically respond quickly to rainfall events. Therefore, the 95th percentile values could be considered reasonable.

The discharge at Swalwell assumes an interpolated elevation that is above the surface level. This is to take in to account any pressure heads required to cause all the flow to discharge at the site.

The borehole at Freeman Road was in twice. Once as Environment Agency data and once as Coal Authority data. The sites had slightly different locations and slightly different water levels and this caused a slight issue with contouring. The Environment Agency data was removed, due to this being historic data.

12. Central Durham South mine water block factsheet

12.1 Description of mine water block

The Central Durham South mine water block extends from Ouston in the north to Durham in the south, Chester-le-Street in the east and Edmondsley in the west.

Currently the mine water levels are controlled by pumping at Kimblesworth shaft. Pumping at Kimblesworth shaft is due to be reduced overtime, and eventually will be switched off. This will result in development of artesian conditions and subsequently a controlled outflow of mine water at the Busty monitoring borehole. This will be the source of the mine water which will be treated at the newly built Kimblesworth mine water treatment scheme.

The south eastern extents of this block are fairly well defined, where there is a wide section, up to approximately 500m, of no recorded mine workings in some areas.

12.2 Contouring methodology

Within the mine water block, there are a total of 7 mine water level monitoring points. There are no current mine water discharges directly associated with the main mine water regime.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods, in this block, the 95th percentile of maximum over a 5 year period from 2012 to 2017.

Two dummy control points were added for the purpose of contouring to the north of the block so that the low ‘pumped’ point at Chester South Moor was interpolated correctly.

Based on historic trends, the water level at Busty artesian borehole is taken as 0.5m higher than the water level at Kimblesworth shaft.

12.3 Methodology for creating future contours

The points used to model the future contours include one controlling outflow at Busty artesian borehole and 5 interpolated points spaced evenly across the block, using a gradient of 1 in 500 to the nearest controlling outflow.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

12.4 Data issues

The types of water level data collected vary across the mine water block. Some sites have continuous data logger data, whilst others have manual readings taken every 1 to 2 months. This can cause difficultly in comparing some of the statistical values used for normal contouring method, for example the 95th percentile of the maximum.

The discharge at the Busty artesian borehole assumes an interpolated elevation that is slightly above the surface level. This is to take in to account any pressure heads required to cause all the flow to discharge at the site. The regional water levels prior to the artesian borehole being drilled have been higher than the surface level of the boreholes. However, there is limited data on gradients using the artesian borehole as a controlling outflow.

13. Dawdon-Horden mine water block factsheet

13.1 Description of mine water block

The Dawdon-Horden mine water block extends from Silksworth in the north, to Seaham, at the coast, in the east, Hesleden in the south and Hetton-le-Hole in the west.

Currently the mine water levels are controlled by pumping at Horden shaft and Dawdon shaft, which each feed into mine water treatment schemes.

The mining block is entirely concealed by the Magnesian Limestone aquifer and groundwater level information for this should be sought from the Environment Agency.

The northern extent of this block are fairly well defined with up to 200m of no recorded mine workings in some areas. The eastern extents of this block are well defined and mark the edge of the coalfield, although for the purposes of this project, the offshore workings are clipped to the low-tide. The southern extents of this block are fairly well defined, with the south east marking the edge of the coalfield. There are areas of up to 150m to 750m of no recorded mine working in the south. The western extents of this block are fairly well defined with a section of approximately 70m to 200m of no recorded mine workings.

A single underground roadway connects the northern part of this block at Dawdon to the southern part at Horden, meaning there is a requirement to pump at 2 sites in the block.

13.2 Contouring methodology

Within the mine water block there are a total of 4 mine water level monitoring points. There are no current mine water discharges directly associated with the main mine water regime. The data used comprises a mix of data logger data and manual readings.

The contours were generated in ArcGIS following the agreed hierarchy contouring methods. In this block, mean values for the last years worth of data have been used in order to correct for tidal influences and to discount for changes in pumping prior to 2016.

Eighteen dummy control points have been added for the purpose of contouring in order for the drawdown cones around Horden and Dawdon to be correctly interpolated.

13.3 Methodology for creating future contours

The points used to model the future contours include 4 controlling outflows at Dawdon Colliery Beach Drift, Easington Beach Drift, Horden Colliery Water Level Drift, Blackhall Water Level Drift and 7 interpolated points spaced evenly across the block, using a gradient of 1 in 500 to the nearest controlling outflow

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

13.4 Data issues

The types of water level data collected vary across the mine water block. Some sites have continuous data logger data whilst others have manual readings taken every 1 to 2 months. This can cause difficulty in comparing some of the statistical values used for the contouring method. It is considered that using mean values for the last years worth of data will correct for any discrepancies and will correct for tidal influences variations in pumping prior to 2016.

In addition to the difference in monitoring frequencies over the past 5 years, please note that all 4 sites have data loggers installed, the coastal sites show diurnal ‘tidal pressure’ related water levels, where the water level varies significantly daily. In the data assessment, daily means of logged data is used where possible.

The future discharges at Dawdon Colliery Beach Tunnel, Easington Beach Drift, Horden Colliery Water Level Drift and Blackhall Water Level Drift assume an interpolated elevation that is above the surface level. This is to take into account any pressure heads required to cause all the flow to discharge at these sites.

14. East Consett mine water block factsheet

14.1 Description of mine water block

The East Consett mine water block extends from Hamsterley in the north to Annfield Plain in the east, Delves in the south and Consett in the west.

It is considered that the mine water levels in the East Consett mine water block are recovered.

The northern extent of the block is very well defined with up to approximately 1km of no recorded mine workings in some areas. The south and western extents of the East Consett mine water block comprise the edge of the coalfield. The eastern extent of the mine water block is not clear.

14.2 Contouring methodology

Within the mine water block there are a total of 14 data points, 13 of which are recorded mine water discharges. The remaining mine water monitoring point comprises Hamsterley John Shaft located on the northern boundary of the mine water block. Although the mine water in Hamsterley John Shaft is controlled by 2 discharges to the surface from shaft culverts. The 2 recorded mine water discharges located approximately 80m north of the mine water block which have been used for the purpose of contouring.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods. For the mine water discharges, the approximate ground levels, rounded up to the nearest metre where appropriate, have been used. For Hamsterley John Shaft, the 95th percentile of the maximum value over a 5 year period from 2012 to 2017 has been used. The data for this monitoring location comprise manual data readings.

14.3 Methodology for creating future contours

East Consett is controlled by the 13 discharges and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

14.4 Data issues

The ground elevations, rounded up to the nearest metre, have been used for the controlling outflows/discharges for the purpose of contouring. There is a possibility that mine water levels are higher than these levels, however this cannot be determined based on the information available and therefore it is considered that the approach is conservative.

15. Ellington-Lynemouth mine water block factsheet

15.1 Description of mine water block

The Ellington-Lynemouth mine water block extends from West Chevington in the north, Ashington in the south, Longhirst in the west and to Lynemouth, at the coast, in the east.

Currently, the mine water levels are controlled by pumping at Lynemouth Colliery shaft in Northumberland. Water levels are being lowered to approximately 40m below ordnance datum (BOD).

The mine water block includes offshore workings, and for the purposes of this project the offshore workings were clipped to the low-tide limit.

15.2 Contouring methodology

Within the mine water block there are a total of 12 mine water level monitoring points. The data comprises a mix of data logger data and manual readings. Along the coast, the mine water levels show a tidal pressure response of up to approximately 1.0m.

Due to the nature of the tidal related pressure responses in mine water level, drawdown since pumping began in 2015 and using a mix of logger values and manual readings, a different approach to the standard methods has been used.

The contours were generated in ArcGIS and followed the agreed hierarchy of contouring methods. These contours were compared to hand drawn contours. It is considered that, despite pumping at Lynemouth No1 shaft, mine water levels are rising in the area and therefore the contours drawn were based on maximum levels recorded in July 2017.

There are no dummy control points added for purpose of contouring.

The water level at Ashington appears to be below that being pumped at Lynemouth. This is likely to be due to a factor of ‘tidal’ variations at Lynemouth and possible minor errors in datum levels used. For the purpose of this project, the water level at Ashington is the same as Lynemouth. This is based on pre-pumping data when they were the same.

There is no water level monitoring data available for Karva borehole since 2010. Based on historical water levels recorded in 2008 to 2010 at the Karva borehole, a value of 5.0m AOD has been used.

As there is no water level data available for New Moor Borehole from July 2017, an average value has been used based on water level data recorded between June 2017 and September 2017.

There is no data available for Ellington No2 Shaft since February 2016. Based on similar historical trends, a water level for Ellington has been set as the same as Woodhorn.

15.3 Methodology for creating future contours

The points used to model the future contours include 3 controlling outflows at Lynemouth No1 shaft, Ellington Blake Moor Drift and Bewick Drift and 5 interpolated points spaced evenly across the block, using a gradient of 1 in 500 to the nearest controlling outflow.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

15.4 Data issues

Some of the water levels used for the contouring use trends in data (such as a site’s usual water level in relation to another site’s water level) to determine the values used, as discussed in Section 2.

The discharges/controlling outflows at Lynemouth No1 shaft, Ellington Blake Moor Drift and Bewick Drift are interpolated as the surface level, rounded up to the nearest 0.5m where appropriate.

16. Fourstones mine water block factsheet

16.1 Description of mine water block

The Fourstones mine water block is rural and isolated from the main coalfield and extends generally from Fourstones in the north east to Brierwood Hill in the south west.

It is considered that the mine water levels in the Fourstones mine water block are recovered.

16.2 Contouring methodology

Within the Fourstones mine water block there is one mine water level monitoring point which comprises a discharge from Fourstones Junction Shaft in the centre of the block.

As there is only one monitoring point within the block, the contours were generated in ArcGIS using the ground elevation at Fourstones Junction Shaft as the controlling outflow and 9 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the controlling outflow.

16.3 Methodology for creating future contours

The Fourstones mine water block is controlled by a discharge at Four Stones Junction Shaft and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

16.4 Data issues

There is only one monitoring point located within the block meaning there is some uncertainty in the interpolated contours. The ground elevation, rounded up to the nearest metre, has been used for the controlling outflow/discharge for the purpose of contouring. There is a possibility that mine water levels are significantly higher than this level, however this cannot be determined based on the information available and therefore the approach is considered to be conservative.

17. Haltwhistle mine water block factsheet

17.1 Description of mine water block

The Haltwhistle mine water block is isolated from the main coalfield and is centralised around the village of Haltwhistle, extending up to Lees Hall, which is north of Haltwhistle, in the north, to Melkridge in the east, Broomhouse Common in the south and Birchfield Gate in the west.

It is considered that the mine water levels in the Haltwhistle mine water block are recovered.

17.2 Contouring methodology

Within the mine water block there is one mine water level point which comprises a discharge named ‘South Tyne’ that discharges to the Haltwhistle Burn located to the north of Haltwhistle.

As there is only one discharge point within the block, the contours were generated in ArcGIS using the ground elevation at the ‘South Tyne’ discharge as the controlling outflow and 16 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the controlling outflow.

17.3 Methodology for creating future contours

The Haltwhistle mine water block is controlled by the South Tyne discharge and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

17.4 Data issues

There is only monitoring point located within the block meaning there is some uncertainty in the interpolated contours. The ground elevation, rounded up to the nearest metre, has been used for the controlling outflow/discharge for the purpose of contouring. There is a possibility that mine water levels are significantly higher than this level, however this cannot be determined based on the information available.

18. Hauxley mine water block factsheet

18.1 Description of mine water block

The Hauxley mine water block extends from Amble-by-the-Sea in the north to the coast in the east, West Chevington in the south and Acklington in the west.

It is considered that the mine water levels in the Hauxley mine water block are nearly recovered, although future contours have been modelled to account for any continued rise.

The northern extents of the block are very well defined and comprise the northern edge of the main coalfield. For the purposes of this project, the eastern boundary is taken to be the low-tide limit and it does not include the full extent of offshore workings.

The southern boundary of the mine workings is well defined by the Causey Park Dyke. The western extents of the modelled block are defined as the limit of the main coalfield, with sections of up to approximately 3.5km of no recorded mine workings. The blocks contain extensive areas of former opencast sites and the impacts of these on the mine water situation is unclear.

18.2 Contouring methodology

Within the mine water block there are a total of 6 mine water level monitoring points. There are no current mine water discharges directly associated with the main mine water regime. The data available comprises a mixture of data logger data and manual readings. The hydraulic gradient across the Hauxley mine water block currently is very gentle.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods and the 95th percentile of maximum values over a 5 year period from 2012 to 2017 have been used.

There were no dummy control points added for the purpose of contouring.

18.3 Methodology for creating future contours

The points used to model the future contours include 1 controlling outflow at Hauxley North Old NCB Borehole and 10 interpolated points spaced evenly across the block, using a gradient of 1 in 3000 to the nearest controlling outflow. This gradient is three times greater, or steeper, than the current gradient across the Hauxley mine water block and is therefore considered to be conservative.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

18.4 Data issues

The types of water level data collected vary across the mine water block. Some sites have continuous logger data whilst others have manual readings taken every 1 to 2 months. This can cause difficulty in comparing some of the statistical values used for normal contouring methods, for example the 95th percentile of the maximum. Where we do not hold any recent data, and where historical relationships are known, approximate water level values have been used for the purpose of contouring.

19. Lambley mine water block factsheet

19.1 Description of mine water block

The Lambley mine water block is rural and isolated from the main coalfield and extends generally from Hartleyburn Common (North Side) in the north to West Garbutt Hill in the east, Halton-Lea-Gate in the south and Hainingburn Gate in the west.

It is considered that the mine water levels in the Lambley mine water block are recovered.

19.2 Contouring methodology

Within the Lambley mine water block there are two mine water monitoring points which comprise a discharge from Lambley Drifts Mid-Tyne Drift and Lambley Drifts Coanwood Discharge. There is a further unmonitored mine water discharge located approximately 250m north of the block which has been used for the purpose of contouring.

The contours were generated in ArcGIS using the ground elevations at the 3 monitoring points as the controlling outflows and 9 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the nearest controlling outflow.

19.3 Methodology for creating future contours

The Lambley mine water block is controlled by discharges at Lambley Drifts Mid-Tyne Drift and Lambley Drifts Coanwood and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

19.4 Data issues

There are only 3 points that have been used for the purpose of contouring meaning there is some uncertainty in the interpolated contours. The ground elevations, rounded up to the nearest metre, have been used for the controlling outflows/discharges for the purpose of contouring. There is a possibility that mine water levels are significantly higher than this level, however this cannot be determined based on the information available.

The 3 mine water points in the block are located very close together in the centre of the block and therefore contours interpolated further away may be less accurate.

20. Lemington mine water block factsheet

20.1 Description of mine water block

The Lemington mine water block is considered to be the smallest mine water block within the main coalfield and extends from East Denton in the north and east to River Tyne in the south and west.

It is considered that the Lemington mine water block is recovered.

The south and western extents are well defined with a wide section, up to approximately 200m, of no recorded mine workings. The north and eastern extents of the block are less defined and there may be some connectivity between Lemington and Central Durham North.

20.2 Contouring methodology

Within the mine water block there is one mine water level monitoring point which is associated with the discharge at Lemington.

As there is only one monitoring point within the block, the contours were generated in ArcGIS using the ground elevation at Lemington as the controlling outflow and 2 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the controlling outflow.

20.3 Methodology for creating future contours

Lemington is controlled by a discharge at Lemington and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

20.4 Data issues

There is only one monitoring point located within the block meaning there is some uncertainty in the interpolated contours. The ground elevation, rounded up to the nearest metre, has been used for the controlling outflow/discharge for the purpose of contouring. There is a possibility that mine water levels are significantly higher than this level, however this cannot be determined based on the information available and therefore the approach is considered to be conservative.

21. Lumley mine water block factsheet

21.1 Description of mine water block

The Lumley mine water block extends from Follingsby in the north, to Durham in the south, Chester-le-Street in the west and Houghton-le-Spring in the east. There may be overflows to neighbouring Dawdon-Horden mine water block located to the east of Lumley mine water block.

Currently the mine water levels are controlled by an engineered gravity outflow at Chatershaugh.

21.2 Contouring methodology

Within the mine water block, there are a total of 6 mine water level monitoring points. As mentioned previously, one of these monitoring points is a current mine water discharge at Chatershaugh which is directly associated with the main mine water regime. The water levels used for contouring are based on data logger data.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods, in this block, the 95th percentile of maximum over a 5 year period between 2012 and 2017.

Two dummy controls points were added in for the purpose of contouring. These were added in to the north east of Chatershaugh in order for interpolated mine water contours to reflect a south westerly flow direction towards the controlling outflow at Chatershaugh.

21.3 Methodology for creating future contours

Lumley is controlled by an engineered discharge at Chatershaugh and the mine water block is considered to be recovered. The future contours are therefore considered to the same as the current contours.

21.4 Data issues

Data for Warden Law has been as the 95 percentile based on data up to May 2015, as data beyond this date is considered unreliable.

22. Scremerston mine water block factsheet

22.1 Description of mine water block

The Scremerston mine water block is rural and isolated from the main coalfield and extends from Spittal in the north to Scremerston in the east, Allerdean Mill in the south and Unthank Moor in the west.

It is considered that mine water levels in the Scremerston mine water block are recovered

22.2 Contouring methodology

Within the Scremerston mine water block there are 2 mine water points which comprises a discharge from Unthank Blue House Farm in the south west of the block and a discharge from Berwick Hill Copper Eye Water Level located along the north eastern boundary of the block. There is a further discharge outside of the north eastern boundary which is also considered to be a controlling outflow.

The contours were generated in ArcGIS using the ground elevations, rounded up to the nearest metre where appropriate, at the 3 controlling outflows and 4 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the nearest controlling outflow.

22.3 Methodology for creating future contours

Mine water levels in the Scremerston mine water block are controlled by the 3 discharges and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

22.4 Data issues

The ground elevations, rounded up to the nearest metre, have been used for the controlling outflows/discharges for the purpose of contouring. There is a possibility that mine water levels are significantly higher than these levels, however this cannot be determined based on the information available and therefore the approach is considered to be conservative.

23. Sherburn-Houghall mine water block factsheet

23.1 Description of mine water block

The Sherburn-Houghall mine water block extends from Sherburn in the north to Shadforth in the east, High Shincliffe in the south and Houghall in the west.

Currently the mine water block is considered to be controlled by overflows to adjacent blocks. The nature of any connections is unclear, however is likely to be connected or overflowing to the adjacent Bowburn mine water block.

The northern and eastern extents of the Sherburn-Houghall mine water block are poorly defined, and there may be overflows to adjacent blocks. The nature of the possible connections to adjacent blocks is unclear.

The southern and western extents of the Sherburn-Houghall mine water block are well defined with sections of up to approximately 650m of no recorded mine workings.

23.2 Contouring methodology

Within the mine water block there are 2 mine water level monitoring points, one in the east of the block at Sherburn Hill and the other in the west of the block at Houghall.

As there are only 2 mine water level monitoring points in the block, contours were generated in ArcGIS and followed the hierarchy contouring method, for example the 95th percentile of maximum over a 5 year period. In addition to the monitoring points, an additional 6 dummy control points were added across the mine water block. These additional points were used to give improved contours.

23.3 Methodology for creating future contours

The points used to model the future contours include one controlling outflow at Houghall and 5 interpolated points spaced evenly across the block, using a gradient of 1 in 500 to the nearest controlling outflow.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

23.4 Data issues

For the purpose of future contouring, the ground elevation, rounded up to the nearest one metre, has been used for the controlling outflow/discharge. There is a possibility that mine water levels are, or could, be significantly higher than this level, however this cannot be determined based on the information available and therefore the approach is considered to be conservative.

24. Silksworth mine water block factsheet

24.1 Description of mine water block

The Silksworth mine water block extends from South Hylton in the north to Hastings Hill in the east, Moorside in the south and New Silksworth in the west.

Mine water levels in Silksworth are monitored by one site and shown to be rising.

The mine workings in the Silksworth mine water block comprise of Silksworth colliery, with deep workings, with the mine workings being almost entirely concealed by the overlying aquifer.

The northern extents of the mine water block are well defined with sections of up to approximately 400m of no recorded mine workings.

The eastern extents of the block are less well defined, with sections of up to 75m of no recorded mine workings.

The southern and western extents of the block are well defined with sections of up to approximately 350m of no recorded mine workings in some areas.

24.2 Contouring methodology

Within the mine water block there is one mine water level monitoring point at the Silksworth borehole located in the south of the block.

The contours were generated in ArcGIS following the agreed hierarchy of contouring methods,and hence the maximum value, and/or most recent data, for Silksworth borehole has been used, along with 3 interpolated points spaced evenly across the block using a gradient of 1 in 500 to the Silksworth borehole.

24.3 Methodology for creating future contours

As the Silksworth mine water block is almost entirely concealed by the overlying aquifer, the worst case scenario for a future discharge is into the overlying aquifer groundwater. The likely pathway for this to occur is via the Silksworth mine shafts at the top of the shaft tubbing. This has therefore been used as the controlling outflow.

In reality, the mine water level should equalise with the source of the inflow, which is likely to be leakage through the overlying strata, however the approach used is considered to be most conservative.

Based on likely sources of water to the mine workings, the mine block is considered unlikely to discharge water at surface. The mine water level would likely equalise with the surrounding groundwater level.

The points used to model the future contours include one controlling outflow at the top of the shaft tubbing in the Silksworth No1 Shaft, which is also similar to the groundwater level, and 7 interpolated points spaced evenly across the block using a gradient of 1 in 500 to the controlling outflow.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

24.4 Data issues

As there is only one mine water level monitoring point in the Silksworth mine water block there is some uncertainty as to the current gradient across the block. It is assumed that the 1 in 500 gradient is a conservative approach.

25. South of Butterknowle mine water block factsheet

25.1 Description of mine water block

The South of Butterknowle mine water block extends from Comforth in the north to Butterwick Moor in the east, Wackerfield in the south and Woodland in the west.

It is considered that mine water levels in the South of Butterknowle mine water block are recovered.

The eastern, southern and western extents of the mine water block are very well defined and demarcate the edge of the main coalfield. The northern extent of the mine water block are fairly well defined with sections of up to 850m of no recorded mine workings.

25.2 Contouring methodology

Within the mine water block there are a total of 19 water monitoring points, 8 of which are surface mine water discharges directly associated with the main mine water regime. Outside of the block there are 6 mine water level monitoring points, or discharges, which correlate well with water levels recorded in the South of Butterknowle mine water block and so have been used for the purpose of contouring. The data comprises a mix of data logger data and manual readings.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods, therefore in this block, the 95th percentile of maximum values over a 5 year period from 2012 to 2017 have been used.

There were no dummy control points added for the purpose of contouring.

25.3 Methodology for creating future contours

Mine water levels in the South of Butterknowle mine water block are controlled by the discharges and the mine water levels are considered to be recovered. The future contours are therefore the same as the current contours.

25.4 Data issues

The types of water level data collected vary across the mine water block. Some sites have continuous logger data whilst others have manual readings taken every 1 to 2 months. This can cause difficulty in comparing some of the statistical values used for the normal contouring method, for example the 95th percentile of the maximum. However, based on the data available it is considered that this approach is reasonable.

The ground elevations, rounded up to the nearest metre, have been used for some of the controlling outflows/discharges for the purpose of contouring. There is a possibility that mine water levels are significantly higher than these levels, however this cannot be determined based on the information available and therefore the approach is considered to be conservative.

Some of the mine water may be discharging in to the groundwater, hence if groundwater levels change the mine water levels could also change in the future.

26. Stanley mine water block factsheet

26.1 Description of mine water block

The Stanley mine water block extends from Tantobie in the north to West Pelton in the east, Burnhope in the south and Annfield Plain in the west.

It is considered that mine water levels in the Stanley mine water block are recovered.

The northern extents of the block are fairly well defined with sections of up to 250m of no recorded mine workings in some areas. The eastern and western extents of the block are fairly well defined with sections of up to 100m of no recorded mine workings. The southern extents of the block are the least well defined with sections of up to 50m of no recorded mine workings.

26.2 Contouring methodology

Within the mine water block there are a total of 12 mine water points, 11 of which are discharges directly associated with the main mine water regime. The data comprises of manual readings and estimated flow rates.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods, therefore in this block, the 95th percentile of maximum values over a 5 year period from 2012 to 2017 have been used.

Four dummy control points were added for the purpose of contouring so that contours below the lowest discharge level were not interpolated.

26.3 Methodology for creating future contours

The mine water levels in the Stanley mine water block are controlled by 11 discharges and the mine water levels are considered to be recovered. The future contours are therefore the same as the current contours.

26.4 Data issues

The ground elevations, rounded up to the nearest metre, have been used for some of the controlling outflows/discharges for the purpose of contouring. There is a possibility that mine water levels are significantly higher than these levels, however this cannot be determined based on the information available and therefore the approach is considered to be conservative.

27. Throckley mine water block factsheet

27.1 Description of mine water block

The Throckley mine water block extends from Dinnington in the north to Blakelaw in the east, Newburn in the south and Heddon-on-the-Wall in the west.

It is considered that mine water levels are recovered in the Throckley mine water block.

The eastern and southern extents of the block are clearly defined. The western edge of the block defines the edge of the coalfield. The northern extents of the block are less well defined.

27.2 Contouring methodology

Within the mine water block there are 5 mine water points, 4 of which are located very close together at Throckley, with the other an unmonitored gravity discharge from Walbottle Winning Shaft.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods. As all of the mine water monitoring points are recorded mine water discharges, the approximate ground levels, rounded up to the nearest metre where appropriate, have been used for each location for the purpose of contouring.

Eleven dummy control points have been added for the purpose of contouring. These interpolated points were spaced evenly across the block, using a gradient of 1 in 500 to the nearest controlling outflow.

27.3 Methodology for creating future contours

Throckley is controlled by the discharges at Throckley and Walbottle Winning Shaft and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

27.4 Data issues

The ground elevations, rounded up to the nearest metre, have been used for the controlling outflows/discharges for the purpose of contouring. There is a possibility that mine water levels are higher than these levels, however this cannot be determined based on the information available and therefore it is considered that the approach is conservative.

28. Trimdon Grange mine water block factsheet

28.1 Description of mine water block

The Trimdon Grange mine water block extends from Wingate in the north to Eden Vale in the east, Trimdon in the south and Coxhoe in the west.

The Trimdon Grange mine water block is concealed by the overlying aquifer and the status of the mine water recovery is unknown, however for conservatism, it is assumed that the mine water levels are rising in this block.

The northern extents of the mine water block are well defined with sections of up to 200m of no recorded mine workings in some areas.

The eastern extents of the mine water block are very well defined with sections of up to 500m of no recorded mine workings in some areas.

The southern extents of the mine water block demarcate the edge of the main coalfield.

The western extents of the block are less well defined with sections of up to 50m of no recorded mine workings in some areas. There may be some connections to the adjacent Bowburn block along the western extents of the mine water block.

28.2 Contouring methodology

Within the mine water block there is one mine water level monitoring point which is located in the south west of the block.

As there is only one mine water level monitoring point in the block, the contours have been generated in ArcGIS. There is no recent data available for the mine water block, therefore the water level used for the current contours is based on water level data presented on a historical International Mining Consultants Ltd map. In addition, 7 dummy control points have been added across the mine water block, using a gradient of 1 in 500 to the controlling outflow, in order for the contours to be interpolated.

28.3 Methodology for creating future contours

The points used to model the future contours include 1 controlling outflow at Raisby Main F Shaft and 7 interpolated points spaced evenly across the block, using a gradient of 1 in 500 to the controlling outflow.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

28.4 Data issues

The ground elevation, rounded up to the nearest metre, has been used for the controlling outflow/discharge for the purpose of future contouring. There is a possibility that mine water levels are significantly higher than this level, however this cannot be determined based on the information available and therefore the approach is considered to be conservative.

The only water level data we have for the Trimdon Grange mine water block is based on an old International Mining Consultants Ltd plan dated 1995; therefore the current contours may be underestimated. However, the ground level has been used for the future scenario and therefore the approach is considered conservative.

29. Walker mine water block factsheet

29.1 Description of mine water block

The Walker mine water block extends from Walkerville in the north to Felling in the south, Low Walker in the east and Gateshead in the west.

The extents of this block are unclear, and there may be a multi-layered mine water regime under parts of Newcastle. There may be overflows to neighbouring mine water blocks of Algernon-Hebburn and/or Central Durham North.

It is considered that the Walker mine water block is likely to be mostly recovered, but future contours have been generated for conservatism.

29.2 Contouring methodology

Within the mine water block there are 2 mine water level monitoring points. There are no current mine water discharges directly associated with the main mine water regime.

It is unknown whether one of the mine water level monitoring points, referred to as Ouse Burn in the west of the mine water block, is directly associated with the mine water in the area. It has been used for the purpose of contouring as it correlates well with other mine water levels in the area, but is likely that this discharge is likely to be recovered mine water in continuity with the groundwater levels in the area.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods. In this block, the 95th percentile values over a 5 year period from 2012 to 2017 have been used.

A dummy control point has been added in the south of the block for the purpose of contouring.

29.3 Methodology for creating future contours

The points used to model the future contours include 4 controlling outflows at Walker, Ouseburn Borehole, Ouse Burn and the dummy control point created for the current contours, plus 4 interpolated points spaced evenly across the block, using a gradient of 1 in 500 to the nearest controlling outflow.

The contours generated in ArcGIS are produced using a different method to the current mine water contours. The future contours are modelled based on mine water elevations increased by 1m from the current contours. This method was used as it is considered that the block is likely to be recovered and using ground elevations at the monitoring locations would result in a change in flow direction.

29.4 Data issues

The types of water level data collected vary across the mine water block. Some sites have continuous data logger data whilst others have manual readings taken every 1 to 2 months. This can cause difficultly in comparing some of the statistical values used for normal contouring method, for example the 95th percentile of the maximum. The main variability is due to pumping and the site does not specifically respond quickly to rainfall events. Therefore, the 95th percentile values could be considered reasonable.

The ground elevation, rounded up to the nearest metre, has been used for the Ouse Burn discharge for the purpose of contouring. There is a possibility that mine water levels are higher than these levels, however this cannot be determined based on the information available and therefore it is considered that the approach is conservative.

30. West of Wear mine water block factsheet

30.1 Description of mine water block

The West of Wear mine water block extends from Langley Park in the north to Sunderland Bridge in the east, Newton Cap in the south and Tow Law in the west.

The mine water levels in the West of Wear mine water block are considered to be recovered.

The southern extent of the West of Wear mine water block is well defined with sections of up to 250m with no recorded mine workings. The western extent of the block defines the western edge of the main coalfield. The northern and eastern extents are less well defined.

30.2 Contouring methodology

Within the mine water block, there are a total of 22 mine water points, 4 of which are current mine water discharges directly associated with the main mine water regime, these are Whitworth Park discharge, West Hunwick North Shaft discharge, South Brancepeth Page Bank engineered gravity discharge and Bowden Close Hutton discharge.

There are also 7 unmonitored gravity discharges in the West of Wear mine water block. The approximate ground levels have been used for the purpose of contouring at these locations. The data comprises a mix of data logger data and manual readings.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods, in this block, the 95th percentile of maximum over a 5 year period from 2012 to 2017.

There were no dummy control points added for the contouring purpose.

30.3 Methodology for creating future contours

The West of Wear mine water block is controlled by the discharges and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

30.4 Data issues

There were 3 further mine water monitoring points within the West of Wear mine water block that were not used for the purpose of contouring due to the data not fitting the understood main mine water regime in the respective areas.

31. Westoe-Wearmouth mine water block factsheet

31.1 Description of mine water block

The Westoe-Wearmouth mine water block extends from South Shields in the north to, the coast in the east, Hendon in the south and Fellgate in the west.

The mine water levels in the Westoe-Wearmouth mine water block are rising and therefore the most recent values, up to September 2017, have been used for the purpose of contouring. There is a pumping test currently underway at Whitburn, which is located in the east of the Westoe-Wearmouth mine water block, however it is considered that recent mine water levels are still representative of the block as a whole and hence are conservative.

The northern extents of the Westoe-Wearmouth mine water block are very well defined with sections of up to approximately 1.4km of no recorded mine workings in some areas. The eastern extents of the block extend past the coast and demarcate the eastern edge of the coalfield. The southern extents of the block are fairly well defined with sections of up to approximately 400m of no recorded mine workings. The western extents of the Westoe-Wearmouth mine water block are very well defined with sections of up to 250m of no recorded mine workings.

The mine water block includes offshore workings, the full extent of which is not included in the mine water block for this project.

31.2 Contouring methodology

Within the mine water block, there are a total of 4 mine water level monitoring points. There are no current mine water discharges directly associated with the main mine water regime.

The contours were generated in ArcGIS following the agreed hierarchy; therefore in this block the maximum or most recent values, up to September 2017, have been used.

There were no dummy control points added for the purpose of contouring.

31.3 Methodology for creating future contours

The points used to model the future contours include 1 controlling outflow at Westoe Crown Shaft and 5 interpolated points spaced evenly across the block, using a gradient of 1 in 500 to the nearest controlling outflow.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

31.4 Data issues

The ground elevation, rounded up to the nearest metre, has been used for the controlling outflow/discharge for the purpose of future contouring. There is a possibility that mine water levels are significantly higher than this level, however this cannot be determined based on the information available and therefore the approach is considered to be conservative.

32. Whittle-Shilbottle mine water block factsheet

32.1 Description of mine water block

The Whittle-Shilbottle mine water block is rural and isolated from the main coalfield and extends from Bilton in the north to Birling in the east and Longframlington in the south west.

It is considered that mine water levels in the Whittle-Shilbottle mine water block are controlled by pumping from a borehole at Whittle Colliery.

32.2 Contouring methodology

Within the mine water block there are a total of 5 mine water level monitoring points. There are no current mine water discharges directly associated with the main mine water regime. There are 4 further mine water level monitoring points within the block but these have not been used for the purpose of contouring as levels recorded indicate that they may be recording groundwater instead of mine water. Some of the mine water monitoring boreholes may be in to ‘perched’ areas of water. These water levels have been used for the purpose of contouring which is considered to be a conservative approach. The data comprises a mix of data logger data and manual readings.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods, in this block the 95th percentile of maximum values over a 5 year period from 2012 to 2017, have been used.

Three dummy control points have been added for the purpose of contouring so that contours below the lowest point, at Whittle, are not incorrectly interpolated.

32.3 Methodology for creating future contours

The points used to model the future contours include 3 controlling outflows at Hazon Borehole, Hart Law Borehole - perched and Grange Pit Borehole - perched and 11 interpolated points spaced evenly across the block, using a gradient of 1 in 500 to the nearest controlling outflow.

The contours generated in ArcGIS are produced using the same method for the current mine water contours.

32.4 Data issues

The types of water level data collected vary across the mine water block. Some sites have continuous data logger data whilst others have manual readings taken every 1 to 2 months. This can cause difficulty in comparing some of the statistical values used for the normal contouring method, for example the 95th percentile of the maximum. However, based on the available data it is considered that this approach is reasonable.

The ground elevation, rounded up to the nearest metre, has been used for the controlling outflow/discharge for the purpose of future contouring. There is a possibility that mine water levels are significantly higher than this level, however this cannot be determined based on the information available and therefore the approach is considered to be conservative.

33. Winstone mine water block factsheet

33.1 Description of mine water block

The Winstone mine water block is rural and isolated from the main coalfield and extends from Walker Hall in the north to Winston in the east, High Cliffe in the south and East Whorley Hill in the west.

It is considered that the mine water levels in the Winstone mine water block are recovered.

33.2 Contouring methodology

Within the Winstone mine water block there is one mine water level monitoring point - a discharge from Tees-side Winston Drift in the east of the block.

As there is only one monitoring point within the block, the contours were generated in ArcGIS using the ground elevation at Tees-side Winston Drift as the controlling outflow and 5 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the controlling outflow.

33.3 Methodology for creating future contours

The Winstone mine water block is controlled by a discharge at Tees-side Winston Drift and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

33.4 Data issues

There is only monitoring point located within the block meaning there is some uncertainty in the interpolated contours. The ground elevation, rounded up to the nearest metre, has been used for the controlling outflow/discharge for the purpose of contouring. There is a possibility that mine water levels are significantly higher than this level, however this cannot be determined based on the information available.

34. Wylam mine water block factsheet

34.1 Description of mine water block

The Wylam mine water block extends from Ryton in the north east to New Ridley in the south west.

It is considered that mine water levels are recovered within the Wylam mine water block.

The northern extent of the block is well defined with up to 100m sections of no recorded mine workings. This area corresponds with the River Tyne.

The eastern and southern extents of the block are well defined and represent the western edge of the main coalfield. The eastern extent of the block is fairly well defined with mine workings extending to the edge of the block.

34.2 Contouring methodology

Within the mine water block there are 2 mine water level monitoring points, both of which are discharges directly associated with the main mine water regime. These are James Consented discharge, which controls the discharge from James Shaft Wylam and Atkinson Drift discharge, which controls the discharge from Clara Vale.

The contours were generated in ArcGIS and followed the agreed hierarchy contouring methods. The approximate ground levels at the controlling outflows have been used for the purpose of contouring along with 5 interpolated points spaced evenly across the block, using a gradient of 1 in 500 from the nearest controlling outflow have been used for the purpose of contouring.

34.3 Methodology for creating future contours

Wylam is controlled by discharges at James Shaft Consented discharge and Atkinsons Drift discharge and the mine water block is considered to be recovered. The future contours are therefore the same as the current contours.

34.4 Data issues

It is considered that there may be some perched mine water in the west of the block based on a reading from Prudhoe. However it is not known whether this is perched mine water or groundwater. This has therefore not been used for the purpose of contouring.

The ground elevations, rounded up to the nearest metre, have been used for the controlling outflows/discharges for the purpose of contouring. There is a possibility that mine water levels are higher than these levels, however this cannot be determined based on the information available and therefore it is considered that the approach is conservative.