Minerals Plan: Key Issues & Options

Derby & Derbyshire Minerals Core Strategy: Key Issues & Options

Chapter 4: A Portrait of Minerals in Derbyshire

Geology of Derbyshire

4.1 The limestones, sandstones and coal measures, which are today exploited commercially in Derbyshire, were formed during the Carboniferous, Permian and Triassic Periods, which covered the time between 354 and 200 million years ago. 

4.2 The river valley sand and gravels were laid down much more recently, during the last ice age (around 14,000 years ago).  Large amounts of sand, gravel, silt and clay were eroded rapidly by glacial melt waters and deposited in wide tracts alongside the major rivers.

Mineral Resources in Derbyshire

4.3 In terms of quantity, Figure 2 shows that by far the most significant mineral extracted in Derbyshire is limestone, accounting for over 90% of all minerals produced (by weight). The next most significant mineral produced in Derbyshire is sand and gravel (9% of production).

4.4 Minerals extracted in smaller amounts include coal (<1%), vein minerals (mainly fluorite & barytes), gas, sandstone, silica sand & clay and shale (all less than 0.1% of the total county production by weight). Although the tonnage of these minerals extracted is low compared to that of limestone and sand and gravel, their higher value per tonne often makes them economically very significant. They are used by several nationally important industries such as brick making, electricity generation and steel making.

4.5 The Minerals Local Plan notes that Derbyshire's other minerals, namely gypsum, ironstone, natural pigments, ganister and peat have been worked in the past. However, in view of their limited occurrence in Derbyshire, and an abundance of deposits elsewhere, they are unlikely to be worked here again in the future.  In some cases (e.g. ganister and natural pigments) their use has been largely superseded by other minerals or changes in process technology.

4.6 Derbyshire's production of limestone is highly significant in national terms, providing over 17% of the UK's supply. Other minerals provide a far smaller proportion of national mineral requirements, although they are still important locally and regionally (e.g. sand and gravel for aggregates use in Nottingham/Derby). 

Figure 2: Comparison of Minerals Produced in Derbyshire and England in 2007 (000s tonnes)

 

Derby City & Derbyshire County

Peak District National Park*

Geographical Derbyshire (i.e. PDNP + DC & DC)

England

DC & DC's % of National Supply (Geographical Derbyshire)

Sand & Gravel

1,157

0

1,157

67,137

1.7% (1.7%)

Sandstone

3

194

197

6,918

0.0% (2.8%)

Limestone

11,610

5,515

17,125

67,378

17.3% (25.4%)

Clay & Shale

606

606

9,269

‡% (6.5%)

Coal

41

0

41

8,729

0.5% (0.5%)

 

12,811

5,709

19,126

 

 

Source: 2007 RAWP Returns, 2007 ONS, 2007 Coal Authority Returns

PDNP Estimated (i.e. ONS - Derbyshire RAWP Returns)

* The Peak District National Park Authority is responsible for mineral planning issues within the National Park. It is included here for completeness (as an important part of Derbyshire) and because some figures used to construct the table do not distinguish between Derby & Derbyshire Mineral Planning Authorities' areas and the PDNP area.

‡ Figures for Derbyshire County and Derby City's share of national supply not available

Figure 3: Significant Mineral Resources and Permitted Sites in 2009

Derived from BGS data with permission of British Geological Survey (c) NERC

(c) Crown Copyright. All rights reserved. 100023251 2010

See Appendix B for Site Key

Significant Mineral Resources & Permitted Sites in 2009 (locations indicative)

Distribution of mineral resources

4.7 As shown by Figure 3; large areas of Derbyshire have some potential for the extraction of a wide variety of valuable mineral resources.

4.8 Limestone resources, whether of aggregates or industrial quality, are located mainly in the north west of the county (Carboniferous), in the Matlock/Wirksworth area (Carboniferous) and in the north east area of the county, east of Bolsover (Permian). In 2009, there were a total of eleven quarries within Derbyshire producing limestone, ten exploiting the Carboniferous resource and one exploiting Permian resources. Two further quarries produce limestone as a result of vein mineral workings.

4.9 Sand and gravel resources are concentrated along the river valleys, the most important being the Trent Valley to the south of Derby, as well as the adjoining river valleys of the Lower Derwent and Dove.  In 2009, there were four active operations spread along the Trent and Derwent Valleys.

4.10 There is a less widespread sand and gravel deposit in the hard rock formation of the Sherwood Sandstones (whilst these are called sandstones they are poorly consolidated and used in the same way as traditional sands and gravels).  It is found in a small area around Mercaston, between Ashbourne and Belper.  This area is worked by one operation.

4.11 There remain substantial resources of coal in the exposed coalfield, particularly in the east of the county in the North Derbyshire Coalfield, despite the cessation of large scale coal production in the 1990s. In 2009 there were four operational sites; one small underground mine and three surface operations.

4.12 Whilst some surface coal resources remain in South Derbyshire this coalfield is of a limited size, urbanised and largely exhausted by previous surface mining operations.

4.13 Additionally, there is a large potential resource of deep coal in north east Derbyshire contiguous with the surface coal resource shown on the map, and dipping beneath the Permian Limestone to the east. However, development of a new deep mine or the re-opening of a closed deep mine seems unlikely due to very high costs.  It is also unlikely that this area would be suitable for coal bed methane extraction due to the low seam methane contents and uncertainty over the permeability of the coals.  Additionally, the area has been worked heavily in the past and operators tend to prefer virgin seams. There may, however, be further opportunities for abandoned mine methane extraction, such as currently occurs at the former Whitwell Colliery, but potential is also low as workings tend to be older and have probably flooded.

4.14 In Derbyshire, brick clay resources are found under the Mercia Mudstone and Carboniferous Clays (mudstones of the Coal Measures Group). Fireclay is found in   association with the coal measures.  These fireclay resources are not explicitly mapped in Figure 2; the carboniferous clays and fireclays are found together with the coal resource.  The Mercia Mudstones are found in a band in the south of the county, as shown on Figure 3 but currently have little or no economic importance.

4.15 In the UK, Workable deposits of vein minerals such as fluorspar and barytes are found exclusively in mineralised veins and related deposits in carboniferous limestone. Fluorspar occurs in only two areas in the UK - the Northern Pennines and the Southern Pennines. Production in the northern area (Durham) ceased in 1999, leaving the Peak area as the remaining potential source. However, production of these minerals in Derbyshire is currently limited to intermittent supply from two sites. The majority of national supply comes from sites within the Peak District National Park.

4.16 Building stone (mostly sandstone and gritstone, but including some limestone) is produced mainly from small quarries in the central part of Derbyshire, but also from the North-West.

4.17 There is some potential for finding conventional oil and gas deposits in Derbyshire, particularly to the east of Calow, Hardstoft and Ironville on the western margin of the East Midlands oil province.  The area to the west has less potential as the main East Midlands reservoir sands, which hold the oil deposit, are absent or only shallow. One site within Derbyshire currently produces methane from an abandoned coal mine.

4.18 There are very limited natural deposits of Silica Sand in Derbyshire and these lie near Brassington.  They have been worked to some extent in the past with little likelihood of being worked in the future.  

4.19 In terms of recycled and secondary aggregates, there were (in 2009) two active sites; Chaddesden Sidings and Callywhite Lane, Dronfield.

Permitted Mineral Reserves[1]

4.20 At 31st December 2008, current mineral reserves (i.e. that part of the overall mineral resource that has planning permission to be worked) of limestone for aggregate uses totalled some 828 million tonnes, enough to last for 95 years at Derbyshire's current level of annual apportionment.  Reserves of industrial limestone are estimated to be around 360 million tonnes, although these serve a wide variety of different markets.

4.21 The cement works at Tunstead Quarry has sufficient reserves of limestone to last beyond the 25 years recommended by the Government.

4.22 Reserves of sand and gravel are significantly lower, standing at some 10.5 million tonnes at the end of 2008. Based on Derbyshire's current level of apportionment, these reserves will only last for about 8 years.

4.23 Reserves of coal were, at the end of 2008 about 1.5 million tonnes, distributed between 3 sites (two operational and one not in operation).  Since the end of 2008, a further 160,000 tonnes of coal has been granted planning permission. The level of future demand for these minerals is not explicitly defined.

4.24 Current reserves of sandstone (at operational sites) stand at around 500,000 tonnes. In 2008, production from these sites was approximately 2,800 tonnes.

4.25 Although there was no production of brick clay in 2008, permission was granted in 2009 for the extraction of 600,000 tonnes of brick clay from Foxlow Tip, Staveley. There are two further clay and shale extraction sites in Derbyshire and whilst there has been no extraction since 2007 at either, there is the possibility of some production in 2009.

4.26 There is currently one site in Derbyshire producing gas (abandoned mine methane) at the former Whitwell Colliery.

1. Whereas figures for the preceding chapter are for 2009, figures in this section are for th situation as of the 31st December 2008 as this was the most up to date information available at the time of publication [back]

Usage & Markets

Limestone

4.27 After extraction, limestone is crushed mechanically to varying sizes and its end use depends either on its physical properties (used as aggregate) or its chemical properties (industrial limestone).  A single bed of limestone can provide rock for both purposes and many of Derbyshire's quarries produce both industrial limestone and aggregate limestone.

4.28 Aggregate Limestone is important mainly for its physical properties. It is used mainly as fill material, roadstone and in the manufacture of concrete.  Around 75% of Derbyshire's limestone aggregates production is sold outside the county. The largest share of these exports is to the North West Region (35% of total production). 15% of total production is sold to other counties within the East Midlands and 25% to other regions, notably Yorkshire & Humberside, the West Midlands and the East of England regions.

4.29 Industrial Limestone is used for a great variety of generally high value industrial processes (such as agricultural and steel industries, sugar refining and glass making and as filler in products such as paints, plastics & rubbers). Markets are national and, in some   cases, international.  A more local use is for cement manufacture and in this case, cement works tend to be located very close to quarrying operations. The cement works at Tunstead uses large quantities of limestone from the quarry in which it is situated.

Sand and Gravel

4.30 This is used primarily in the manufacture of ready mixed concrete, pre cast concrete products and as a bulk filling material.  In Derbyshire, a high percentage of sand and    gravel is used in the manufacture of concrete.  Most of the active pits in Derbyshire have ready mixed concrete plants on site, producing concrete for the pre-cast concrete plants within the county. These serve a national and regional market for products such as blocks, floors, pipes, kerbs and street furniture.  Sand is used mainly in the production of   mortars and asphalt, or as building sand.

4.31 Most sand and gravel originating in Derbyshire is used within 10 - 15 miles of the pits, mainly because of the high cost of transporting the material, but also because of competition from other sources of aggregate in the area. In 2005, 21% of total sand and gravel output from Derbyshire was used within the county, with 73% being exported to elsewhere in the East Midlands and most of the remaining 6% used within the Yorkshire and Humber and West Midlands regions.

Coal

4.32 Derbyshire coal is of a quality suitable for use by the electricity industry in power generation. The nearest coal fired power station is at Ratcliffe-on-Soar in Nottinghamshire.  Over the longer term there is likely to be increasing pressure on coal resources as additional technologies to extract coal become economic, such as underground gasification. New uses for coal, such as substituting for chemical uses where oil and/or gas are currently used, may also become economic.

Clay

4.33 Brick clay is the term used to describe clay, shale and mudstone used in the manufacture of structural clay products.  The largest use is for facing and engineering bricks, followed by pavers, clay tiles and clay pipes. Clay is a high volume, low value commodity, and as such is expensive to transport long distances. Manufacturing facilities for clay products are often located close to the source of clay. Fireclays are used in the manufacture of   refractory products, i.e. furnace linings, and are also an important raw material for the manufacture of engineering bricks. Cream and buff coloured bricks are manufactured from fireclay as it has a low iron content.

Vein Minerals

4.34 There are two vein minerals which are significant in Derbyshire; Fluorspar and Barytes. Fluorspar was used as a flux in the manufacture of steel. The recent decline in the British steel industry and new technology has negated this.  All Fluorspar ore mined in Britain is now processed to produce Hydrofluoric acid, which is used in a variety of industrial processes. Barytes is produced in small amounts in Derbyshire. Due to its relatively high density, it is used mainly as a weighting agent in drilling mud in the offshore oil and gas industries. It is also used as a filler in paper, textile, rubber, plastics, oilcloth and linoleum manufacturing and as a pigment in paint.

Oil & Gas

4.35 Both are internationally traded commodities with a wide variety of uses.  Gas can be used either close to its point of extraction or can be transported by road or fed into the national grid.

Sandstone (for building stone)

4.36 The market for traditional building stone is small and is mainly concerned with the restoration of historic buildings or with the repair/extension of existing properties or new build properties in areas of high environmental value. The specific properties and value of the stone mean that it is often economically viable to transport it substantial distances.

Recycled & Secondary Aggregates

4.37 Recycled Aggregates & Secondary Aggregates materials can be used to provide bulk fill for construction projects, in concrete manufacture, road surfacing and for the manufacture of light weight aggregate blocks. Due to their low value, the market will tend to be for local construction projects.

Contribution to the local economy

4.38 In 2007, approximately 1,700 people were employed by the minerals industry in Derbyshire (incl. the Peak District National Park). We estimate that up to 50 million pounds is paid annually in salaries to employees in the minerals industries in Derbyshire, with many of these jobs located in rural areas where employment can be scarce.

4.39 The minerals industry in Derbyshire also supports a network of production and processing facilities, such as the cement works at Tunstead and the brick works at Chesterfield.  In turn, these industries supply the raw materials for other essential industries, such as construction.

Transportation

4.40 Most of the minerals produced in Derbyshire are transported by road.  Generally, rail links are only viable at high volume, long life quarries where the significant capital costs can be recovered, although smaller operations can sometimes access the rail network when opportunities arise. In 2007, there were three active rail facilities in Derbyshire, at Tunstead Quarry, Dowlow Quarry and Doveholes Quarry and three inactive rail facilities at Hillhead Quarry, Whitwell Quarry and Hindlow Quarry (which is however used for imports from Tunstead).

4.41 Additionally coal has been transported from the Oxcroft Coal Disposal Point near Bolsover by rail and there is a current planning application pending for the retention of this use.

Reclamation

4.42 Generally, mineral extraction by its nature is a temporary use of land although one which in some cases may last for many years. Once extraction has ceased the site must be restored to its former use or to another suitable and beneficial new use, such as agricultural, wildlife or leisure uses. The type of restoration possible will be affected by site specific issues and the type of quarry that existed, for example it would not be possible for the large limestone quarries in the Buxton area to be restored to their original ground levels, although they can often be reclaimed for agricultural use within a changed landscape setting.

4.43 In Derbyshire many of the currently operational quarries have conditions requiring their restoration to agriculture and/or amenity uses. Some quarries currently have no agreed restoration scheme, an issue on which we will need to work positively with the mineral operators concerned.

4.44 Although in the past, most of the permitted sand and gravel workings in Derbyshire have conditions requiring their restoration to agriculture, restoration to water uses is becoming more common as inert fill material becomes increasingly scarce. Where sites are close to airports, this has to be balanced against the need for restoration schemes to take into account and mitigate the risk of birdstrike.

Legacy of mining

4.45 The extensive history of mining and quarrying within Derbyshire has left an environmental legacy, but one which should not be overstated. Whilst there are many former quarries in Derbyshire, most are small and having blended into the landscape over time, do not have a significant detrimental impact on the local area.

4.46 Although underground mining is currently no longer so environmentally significant, potential public safety and stability problems can still be triggered and uncovered by development activities. Such problems can include the collapse of mine entries and shallow mine workings, emissions from mine gases and spontaneous combustion and the discharge of mine water from abandoned coal mines.

4.47 Within the Derbyshire area, there are approximately 9,800 recorded mine workings and large areas of shallow mine workings.  To date, around 185 hazards related to coal mining related have been recorded.  To address this issue; the Coal Authority along with North East Derbyshire, Chesterfield & Bolsover District Councils are working on a map to help identify areas where issues (e.g. ground instability) resulting from the legacy of coal mining in Derbyshire need to be considered when determining planning applications.

  

Key Points from the Portrait of Minerals in Derbyshire:

 

  • Derbyshire has a nationally significant role to play in the provision of aggregate minerals, including crushed rock and sand and gravel and limestone for industrial uses.

  • There are several other minerals worked in Derbyshire, including sand and gravel, coal, gas, vein minerals, building stone and brick clay, for which demand could increase in the future.

  • Mineral extraction can have a variety of impacts on its surroundings, from increased noise and traffic, to a potential wide impact on the landscape, although these can be reduced by careful site design and management.

  • Road transport is generally good in the east and south of Derbyshire, around the M1, A38 and A50, but there are significant road transport constraints in other hillier areas in the west and north west.

  • The impact from mineral workings continues once extraction has ended. We need to consider after uses and how the final landform will fit in with its wider setting, especially given the scale and long term nature of mineral extraction in Derbyshire.