Cleveland Potash Limited 2012 Supplement to Environmental Statement
Cleveland Potash Limited Boulby Mine, Loftus Saltburn-by-the-Sea Cleveland. TS13 4UZ
Supplement to Environmental Statement
May 2012
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Contents
1.0 Introduction ...... 3
2.0 Reason for application ...... 5
3.0 General description of the area ...... 6
4.0 Proposed mineral development ...... 14
5.0 Subsidence predictions and computer modelling...... 15
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1.0 Introduction
1.1.1 In 1968, following a Public Inquiry, planning permission was granted to Cleveland Potash Ltd (CPL) for the underground winning and working of minerals (potash and salt) from an area of approximately 8,200 hectares which extended from Brotton in East Cleveland Area into the National Park. Permission was also granted for the erection of buildings, machinery and plant at the mine site at Boulby. In 1969, work began on the construction of two mine shafts and in 1973 the first potash was extracted from the mine. Since that time, CPL have successfully been supplying customers around the world with potash products mined and refined at Boulby.
1.1.2 In addition to supplying potash products, Boulby mine is also responsible for supplying approximately half the de-icing rock-salt used to keep the country’s roads safe each winter, without this supply of rock-salt from Boulby imports of salt into the UK would be necessary.
1.1.3 The Environmental Statement was submitted as part of the planning application made on 2 September 1996 and related to a proposal for “Retention of existing potash and salt mine, including all surface installations, buildings, plant, etc. and extension to approved underground mine working area to South” The purpose of the Environmental Statement was to examine the environmental effects of CPL's future operations at Boulby Mine, that is situated within the North York Moors National Park. A copy of the Environmental statement is attached.
1.1.4 Planning permission was granted on 6 May 1998 where permission authorised mining of potash and salt and to retain the surface installations, buildings and plant for the processing of those minerals only until 6 May 2023, a period of twenty five years. The planning permission contained several conditions, the reasons for which were identified as part of the planning decision document No. NYMR/003/043B/PA, a copy of which is also attached.
1.1.5 One of the conditions contained within the planning decision document related to restrictions within the authorised mining area. This condition (Condition No.4) was sub- divided into two sections, Section ”a” related to an area around Loftus, Skinningrove and Brotton and Easington, Section “b” related to extraction of mineral or any other underground development within 1.5km of the coastline (high water mark). The reason for these conditions was included within the planning authorisation document and was stated as being “To take account of concerns relating to mining under established urban area and concerns relating to coastal erosion, coastal processes and possible sea level rises”.
1.1.6 Since that time CPL has continued to mine potash and salt within the terms of the planning permission. Boulby mine continues to be a major employer in the area and the Mine has a substantial effect on the local economy. CPL are aware of their responsibilities towards local communities and the environment and will continue to ensure that all their activities are assessed for their environmental impact and that procedures are in place to eliminate or minimise any impact their activities may have on the environment. CPL operates an environmental management system to ISO 14001:2004 and has formulated policies and procedures to ensure the environmental objectives are met. CPL also has EMAS certification for its Environmental Management System.
1.1.7 The 1996 Environmental Statement Section 4.4 of the key issues states ”It has been recognised since the inception of the Boulby Mine that underground mining will eventually cause subsidence at the surface. Indeed, this is the principal mechanism by which underground activities can possibly interact with receptors at the surface and is, therefore, considered to be a key issue” .
1.1.8 Subsidence has been continually occurring in the area since production first began at Boulby Mine in 1973 and a surface area of land over 50 square kilometres on-shore, 70
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square kilometres offshore and 15 linear kilometres of coastline has now been affected by mining subsidence although there are no visible signs of any subsidence and there are no records or instances of any damage to any properties, structures, land, coastline or any water course, wildlife habitat or ecological system due to underground workings at Boulby Mine.
1.1.9 Since mining first began in 1973 a total of 95 million tonnes of potash ore and salt have been hoisted out of the mine. This mineral extraction has created a void underground of 45 million cubic metres. It is the creation of this underground void and the subsequent roof lowering that is the source of the subsidence observed on the surface ground levels.
1.1.10 Subsidence monitoring has been carried out since 1976 and the observation lines now total over 40 kilometres in length. This monitoring system will continue to expand in advance of the mine workings and improvements in surveying technology will continue to be introduced.
1.1.11 All the subsidence that has been observed has been of a gradual nature with a shallow dish shaped depression forming above the workings, the edges of the dish shape spreading over a very wide area. This subsidence can only be detected by precise survey observations over long periods of time.
1.1.12 Potash reserves have been identified in the deep south east of the mine, these reserves lie within the zone that is the subject of the planning condition No.4b.
1.1.13 A large amount of research work has been carried out or funded by CPL over the last twelve years in order to address the concerns identified in condition No. 4. The results of these years of research have led to an unrivalled understanding of the coastal processes pertaining to this stretch of coastline and the development of a computer modelling system that will predict the effects of any particular mining layout on the surface.
1.1.14 The 1996 Environmental Statement identified that there was no evidence which suggests that mining activity has increased coastal recession. This document is intended to provide additional information to that contained in the Environmental Statement in order to address the concerns raised in Section 4b of the planning consent.
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2.0 Reason for application
2.1.1 Generally a mine will continue operation as long as there are sufficient minerals to economically extract. A key requirement of any mining operation is the need for investment in new equipment to maintain efficient operations, sufficient reserves are required to be able to justify that investment.
2.1.2 Areas of workable mineral are discovered by exploration techniques and once identified as being recoverable these areas are classed as “Mineral Reserves”. Once an area has been identified as being capable of supporting viable levels of production, a mining plan is developed and manpower and equipment is deployed in order to recover those reserves. As existing reserves are mined out, exploration continues in order to find new reserves in other working areas.
2.1.3 Mineral reserves can only be worked where they are found and as such the mining operations involve a continuous process of movement from existing mining areas into new areas. As the old area becomes exhausted the mining equipment is salvaged and moved into the new working area. Proving new reserves by exploration and opening up of new areas in a mine can often take several years.
2.1.4 As part of the previous planning application in 1996 Cleveland Potash had identified the need to extract minerals from beyond their existing planning permission boundary in order to ensure the future viability of their operations. A similar situation now exists where there is a need to expand the onshore working area in order to maintain continuity of production.
2.1.5 Longer term exploration and development will continue offshore in the north and east of the mine.
2.1.6 It was stated in Section 8.12 of the 1996 Environmental Statement that “Although it is not anticipated that mining will take place in the coastal area in the near future, CPL appreciate that the coastal zone represents a particularly sensitive element within the application area. Therefore, CPL undertake to give due consideration in future mine planning to: • Limiting extraction and workings within the coastal zone, • Providing protection zones adjacent to sensitive structures and areas, and • Provide subsidence data and information relating to future mining areas to the statutory bodies involved in the design of coastal structures and preparation of the Shoreline Management Plan”.
2.1.7 Sixteen years have elapsed since the above statement was made and during that time CPL have limited requests for workings within the coastal zone to three previous occasions.
2.1.8 As stated in the introduction potash reserves have been identified in the south east of the mine, these reserves lie within the 1.5km zone that is the subject of the planning condition No.4b of the planning permission. CPL now submit a Supplement to the Environmental Statement giving additional information on their proposals in this area including detailed information on the proposed potash workings.
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3.0 General description of the area
3.1.1 The Proposed Development relates to proposed potash workings under land immediately to the east of Ellerby and to the south west of Runswick bay and is shown on the attached plan Ref. CPL/2012PA/1. The approximate area of the land shown bounded in red is 163 ha.
3.1.2 The application area falls within the boundary of the North Yorkshire and Cleveland Heritage Coast. It is also within 1.5 kilometres of the coastline and as such falls within condition 4b of the 1998 planning permission.
3.1.3 The Cleveland Way National Trail also passes through this stretch of coastline.
3.1.4 The coastline in the proposed zone stretches from Rosedale Cliffs in the north through to Kettleness Sand. There are numerous sensitive receptors within this stretch of coastline including National Trust Holdings, Sites of Special Scientific Interest, Scheduled ancient Monuments and Conservation Areas, these are identified in the North Yorkshire and Cleveland Heritage Coast Management Plan, a copy of which is attached.
3.1.5 The geology of the area is generally made up of recent (two million years) Glacial Till and Boulder Clays overlaying sandstones, shale and mudstones of the Jurassic age (two hundred million years) Lias and Ravenscar Groups with areas of the Cleveland Ironstone formation showing on the foreshore. The area is crossed by several small faults and jointing in a north-south direction is visible in the mudstones throughout the foreshore.
3.1.6 There are several water courses that fall within the area all of which eventually fall steeply into Runswick Bay. The closest of these to Runswick village is Nettledale beck which runs down the side of the car parks at Runswick followed by Limekiln Beck and Calais Beck that enter the bay in the area of the Sailing Club. The furthest east is Claymoor beck which is the largest of these features and has cut a steeply sided erosive channel through the surrounding mudstones and marls. Further inland Barnby Dales and Widgeytoft Gill form tributaries to Calais Beck and Claymoor Beck.
Limekiln Beck as it enters Runswick Bay
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Calais Beck as it enters the bay by the Sailing Club
Claymore Beck as it enters the Bay to the east of Hob Holes
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Claymore beck .
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Claymore Beck
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3.1.7 Land use is predominantly grazing although there are areas of arable farming and woodland. The following photographs show typical views of the application area, the first is the view looking South West above Calais beck with Westfields Farm to the right of centre.
View looking south west across Claymore Beck towards Westfields Farm.
View looking south up Widgeytoft Gill from the coastal footpath.
3.1.8 The Topography is typical of the area with undulating glacial drift cut through by steep sided valleys.
3.1.9 The coastline of the area is known both nationally and internationally for its geological importance. This section of coastline is predominantly made up of near vertical cliffs of Jurassic age interspersed with low lying sandy bays and beaches.
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3.1.10 The surface rocks and drift deposits contain a wealth of mineral deposits that have been exploited from roman times up to the present day, extraction of these minerals have all had an effect on the coastal landscape and are evident both to the east and west of the bay.
Old Jet workings at the east side of the bay (Hob Holes)
Old ironstone quarry waste at the west side of Runswick bay
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View from Runswick village looking south towards the sailing club buildings
3.1.11 The standard port for tides at Runswick is Whitby, approximately 9 kilometres to the south east of Runswick bay. The National Oceanography centre website shows the tidal predictions for 2008 to 2026 and gives MHWS level of 5.59m and MLWS level of 0.99m giving a range of 4.60m. MHWN is 4.50m, MLWN 2.25m giving a range of 2.25m. The HAT figure is quoted as 6.21m, LAT is 0.22m.
3.1.12 The following photographs were taken on 8 May 2012 on a Spring tide when low water was quoted as 0.6m and high water 5.70m.
Low water at Runswick Bay
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High water at Runswick Bay
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4.0 Proposed mineral development
4.1.1 The mineral reserves in the proposed development area have been identified by underground boreholes drilled between 2002 and 2006.
4.1.2 The depth of the proposed development is between 1230 metres and 1310 metres below the surface.
4.1.3 The minimum horizontal distance from the proposed workings to the coastline is 500 metres.
4.1.4 The proposed potash workings are an extension to existing potash workings that were mined between 2006 and 2007.
4.1.5 Potash production from the proposed development area will commence early 2013 and is phased to provide continuity of production from existing reserves in the area. In practice the geology and mining conditions are difficult to accurately predict and a precise start date is difficult to determine.
4.1.6 Potash workings will be by the conventional modified room and pillar method normally used at Boulby. Exact panel and pillar dimensions will depend upon underground conditions but will be similar to the existing dimensions of workings.
4.1.7 Additional salt development to maintain access will be required as potash mining progresses.
4.1.8 Workings are planned to commence at the south east side of the proposed development in 2013, gradually working through the area and finishing in the north west by 2017.
4.1.9 CPL will supply suitable plans showing mining progress of workings in the coastal zone as part of the routine subsidence monitoring report.
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5.0 Subsidence predictions and computer modelling.
5.1.1 A large amount of observations and research into potash mining subsidence has been carried out by CPL. A more detailed study of the subsidence monitoring information is shown in the Annual reports produced by Durham University.
5.1.2 In order to assist in future predictions a subsidence prediction model has been developed at CPL, based on actual observations taken at Boulby. The subsidence model has been developed from over thirty years of measurements and observations and will predict expected values for different mining layouts.
5.1.3 Computer modelling of subsidence is not new, an early subsidence prediction model was introduced by the NCB in 1987. This “Mulpan” system was trialled at Boulby although was found to be unsuitable due to the differences in the partial extraction mining systems in place at Boulby and the total extraction longwall systems employed in the coal industry at the time.
5.1.4 Independent modelling of subsidence at Boulby was then carried out by Durham University in 2006. This model has subsequently been developed as further information has been included. The figures generated by the model are the final subsidence and it should be noted that it can take many years to reach these values.
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