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Chapter 8 Loss of soil to development and mineral extraction

This chapter discusses soil sealing through residential, industrial or transport development and mineral extraction, the scale of the issue in a national and regional context, the impact on soil by these developments and information on trends, scale and location of developments.

8.1 Summary

• Data on the loss of land and soil as a result of development is not collected in a consistent manner either at the national or regional level.
• Based on the limited information available, land appears to be being developed at a higher rate than at any time during the last 50 years; this raises questions about the sustainable use of resources and whether soil is being recognised and protected by the planning system.
• Soil lost to development is unable to fulfil any of its other functions; some such as biomass production is almost eliminated.
• There should be encouragement to re-use the soil that is removed during the construction phase.
• Based on previous data, a disproportionate area of our good quality and most flexible soils is lost to development; many of Scotland's settlements are located next to the best land within that area. As new developments tend to 'grow' from existing urban areas, this trend is likely to continue.
• Given the recent findings on reductions in soil organic matter levels (Chapter 2) and role that Scotland's organic soils have in Scotland's climate change programme (Chapter 3), it is recommended that data on peat extraction be collected centrally by the Scottish Executive.
• It is recommended that mechanisms be set in place to capture data on land and soil loss to development. In addition to location and area, information on soil type and quality should also be recorded.

8.2 Introduction and Description of Threat

Built development frequently results in the loss of existing soil cover and of many of the functions it previously performed. This does not directly equate to soil loss as the soil is usually stripped prior to construction and reused elsewhere in verges, amenity ground or as part of the remediation process on brownfield or derelict sites. However, soil reused in this way cannot be directly compared with soil in its original state as in all likelihood it will have been disturbed and the original horizons mixed to some degree.

Not all the land that is developed is 'sealed' and a certain proportion is retained as open space in the form of gardens, parks, amenity areas etc. There is an increasing awareness and requirement that these provide vital 'lungs' within our cities and towns. There is a consultation currently (August - November 2006 ) on planning for open space in new developments (excluding domestic gardens) in which minimum open space standards are recommended (Scottish Executive 2006). These vary according to the type of development; for most types of development, the suggested area is between 6 - 18 m ² per 100 m ² of gross floor area. This equates to 6-18% but when roads and pavements are taken into account, the proportion of the total area will be less. In residential areas, the figure is expressed differently as 60m ² per household. Similarly not all land with existing urban areas is completely sealed, the most obvious of these are parks and domestic gardens.

Mineral extraction includes removal of the soil resource itself, for example peat, or disturbance of the soil to allow extraction of the underlying material for example sand, gravel, bedrock or increasingly in more recent times, coal.

8.2.1 Impact on soil functions

Biomass, food and fibre production

Loss to development prevents soil performing this function to any great extent. Although some land will be retained for gardens and allotments, the rural attributes and food production capacity of the land has largely gone for good.

Environmental Interactions

This function has been seriously diminished, but is retained to some small degree in gardens, amenity areas, roadside verges etc. However the major impact on soil function is the reduction in infiltration of water which leads to change in hydrological regimes in rivers, specifically greater runoff and peak flows. Increases in the area of sealed hard surfaces will be offset to some extent by the implementation of Sustainable Urban Drainage Systems ( SUDS) which uses the natural capacity of soils to help prevent or minimise flood risk.

Support of ecosystems, habitats and biodiversity

The current planning system and designation of sites of high conservation interest should prevent development on land with valuable and/or rare habitats and sites of high biodiversity. It is also worth pointing out that most of the extensive areas of valued and/or rare habitats in Scotland are not found adjacent to potential development sites. However, there are likely to be specific areas where conflicts may arise, notably on the location of wind farms and where conservation and development objectives may clash, for example within National Parks.

Green space within urban areas does provide the necessary 'lungs' for the well-being of the location itself but also of its residents and can contain elements of biodiversity not found in rural areas. Many of these are highly desirable, for example where contaminated land has been restored or where derelict land is being managed in such a way so that biodiversity objectives are promoted. However, many non-native species are introduced into urban areas which, in this context, is undesirable. Overall, soil sealing has a highly negative impact of the biodiversity function of soil.

Provision of raw materials

Soil stripping is part of the land development process and, ideally the soil removed should be re-used on site for landscaping and amenity areas. As a substantial proportion of the site is likely to be covered by buildings, roads etc, surpluses are likely to occur. These can be used in areas, particularly of redevelopment, where topsoil is in short supply but clearly this requires a high degree of co-ordination. It must also be recognised that there are environmental and economic costs associated with the transport of soil as well as the social costs of dust and noise nuisance.

Protection of cultural heritage.

Soil protects archaeological remains but also provides a record within it of previous cultivation and improvement and therefore of the development of landscapes and societies. It might be argued that urbanisation is another step within the process of change, but the disturbance and redistribution of soil associated with that does destroy any historical record of change captured within the soil.

8.3 Policy

Planning policy and locational priorities for different types of development are identified within structure and local plans. These will have gone through a public consultation process and various committee debates at Unitary Authority level before being approved by the Scottish Executive. Soils are not explicitly protected but those within SSSIs and the Natura suite of protected sites will have indirect or implicit protection from development as clearly any disturbance on the scale caused by building operations will have a serious impact on the integrity of designated sites. In addition, development plan policies designed to prevent urban sprawl (including the designation of clear settlement boundaries) and to protect countryside and green belts afford significant protection to soils.

The Town and Country Planning (Scotland) Act 1997 requires that development plans include measures for the "conservation of natural beauty and amenity" and the "improvement of the physical environment". There are a number of Scottish Planning Policies ( SPPs), National Planning Policy Guidelines ( NPPGs) and Planning Advice Notes ( PANs) that provide further information and advice on a wide range of planning issues. See:
http://www.scotland.gov.uk/Topics/Planning/AdviceGuidance/PANs
http://www.scotland.gov.uk/Resource/Doc/83958/0036126.pdf

Until 2002 National Guidelines existed that sought to protect the most versatile agricultural land from development unless there was no other suitable site for the purpose. In 2001, the Scottish Executive issued a consultation paper proposing that the blanket national protection afforded to prime agricultural land (Land Capability for Agriculture Classes 1, 2 and 3.1 (Bibby et al 1991)) be removed and that the planning authorities be given flexibility to determine for themselves whether such land should be used for new development. After consideration, the Executive decided to remove the blanket protection and argued that 'Prime agricultural land will continue to be protected through relevant policies in National Planning Policy Guidelines and Circulars (for example, Green Belt policies) and Ministers will still have an overview of prime land, given their role in approving structure plans and being informed of any significant proposals contrary to structure plans.

Within the Scottish Executive's Sustainable Development Strategy (Scottish Executive 2005), it is acknowledged that we must live within the limits of our natural resources. The introduction of Strategic Environmental Assessment means that development plans will in future be considered at a very early stage to identify and mitigate potential impacts on, for example, biodiversity, soil, water, air and landscape. The Scottish Parliament has recently passed a Bill extending the scope of European requirements to cover all public sector plans, programmes or strategies with significant environmental effects.

8.4 Evidence

8.4.1 Current status

Built-up land is quite difficult to define and as a result a definitive statement on its location and extent is difficult to obtain. In 1988, the Land Cover of Scotland dataset estimated that 1.8 per cent of Scotland was described as urban and a further 0.6% as rural development. This latter category included features that clearly equate with soil sealing, such as road and rail infrastructure, factories and airfields, whilst others are clearly associated with mineral extraction activities such as quarries. The National Countryside Monitoring Scheme ( LCMS) arrived at a figure of 1.7% of urban land cover for the late 1980s ( http://www.snh.org.uk/strategy/Landcover/results/built.asp). A follow up analysis covering 1990-1998 (the Countryside Monitoring Scheme) estimated the urban area at 2% and for transport features at 1% although these numbers have been rounded. The Scottish Office (1998) classified 2.6% of the Scottish land surface as urban. More recent estimates could not be found readily on the Scottish Executive website. Care must be taken in the interpretation of these numbers; the differences are likely in part at least to be due to differences in definition and method of data capture.

The area of urban land as a proportion of the total area varies widely across Scotland and any national data masks that variation. Clearly the four major cities have the highest proportions but there are a number of other Unitary Authorities that have urban percentages much higher then the national average. They are all in the Central Belt and include East Dunbartonshire (14.6%), East Renfrewshire (8.3%), Falkirk (6.8%), Fife (8.8%), North Lanarkshire (15.3%) and West Lothian (10.7%). Along with the City authorities, these are all close to or well above the EU average of 7% (Prelier 2005) . Disaggregating Scotland in this way does identify the well recognised population imbalance across Scotland and those areas where pressure on land is greatest. More information can be found at: http://www.scotland.gov.uk/library/stat-ses/sest2-1.htm

8.4.2 Data availability

Precise and consistent data on changes in urban land area are difficult to obtain. The best source of change in the second half of the 20 ^th century is the LCMS as a consistent methodology was applied between 1946 and 1988. The method was based on a random sampling strategy rather than a full census. Increases of 22% and 46% were reported in transport corridors and urban land respectively and in 1988, when combined represented approximately 2.7% of the land area of Scotland. No significant change was found in the area occupied by quarries. The increase of 46% in urban area equates to approximately 400 km ² (40,000 ha) most of which was lost from improved grassland and arable land. For more details see ( http://www.snh.org.uk/strategy/Landcover/method.asp)

Between 1970 and 1999, 25,217 ha of agricultural land were converted to roads, housing and industry and 9,481 ha to mineral workings (Scottish Office 1998, quoted by Birnie et al., 2002). These figures may be an underestimate of the conversion of all land to built infrastructure. In absolute terms they represent annual conversions of approximately 850 and 316 ha respectively.

The most recent data on conversions from agricultural land are presented in Table 8.1. Conversions to recreational land are included for comparison. Between 1989 and 1996, the conversion of land to roads, housing and industry was approximately 700 ha yr ^-1. In the succeeding seven years this rose to c. 1,200 ha yr ^-1. As previously described, these figures do not equate directly to soil sealing as a proportion of the land will be retained as amenity grounds, domestic gardens etc. There is a range of different standards set by different Councils for the provision of open space and for garden sizes and a number of these are difficult to convert to percentage areas as they are based on population rather than area. If we assume that the suggested thresholds in the current consultation (Scottish Executive 2006) represent a reasonable consensus of current guidance, then around 10-12% of these recent developments, excluding domestic gardens, might be considered to remain unsealed. However, the soils are likely to be in a different state and will perform quite different functions than prior to development.

There is also an increase in the rate of conversion of land to mineral workings, although these figures are heavily skewed by individual years.

Table 8.1 Conversion of agricultural land to selected other uses.

Source: http://www.scotland.gov.uk/Publications/2005/06/2290402/05121

There is clear, albeit incomplete, evidence that soil sealing has been taking place over the last half century, and at an apparently increasing rate in recent years, during a time when the total population was static.

This trend has taken place at the same time as substantial and welcome decreases in the amount of vacant and derelict land in Scotland. Decreases in the amount of derelict land and vacant urban land recorded fell from 15,400 ha in 1993 to 10,661 ha in 2004. Compared with the previous survey, 466 ha of vacant and derelict land were brought back into productive use. The main new use for this land was residential development (285 ha). There is clearly development pressure on both brownfield and greenfield sites and although the former offer a number of advantages in relation to the sustainable use of Scotland's land, many of these should be restored for use as amenity land.

Source: http://www.scotland.gov.uk/Publications/2004/12/20392/48569

There are a number of datasets and techniques that could be deployed in the future for monitoring rates and locations of built development. These include:

• Land Cover of Scotland 1988 ( MLURI, 1993). This dataset provided an excellent snapshot of land cover at a specific date but it is almost 20 years old.
• Countryside Survey 2000. This dataset is based on a sampling framework of 1 km ² squares in which land use was mapped in both 1990 and 1998. Estimates are available for these two dates but differences in the interpretation in the two maps prevent their use in estimating change over time (Haines-Young et al 2000)
• Land Cover Map ( LCM 2000). This dataset, captured from satellite imagery, does offer potential for future monitoring (Fuller et al 2005).
• OS mapping. There is a lag between changes actually occurring and those changes being recorded, with the majority being picked up after 5 years of surveying.
• Remote sensing. In their report in 2004, describing the potential of remote sensing to deliver soil monitoring, Wood et al. concluded that it had the greatest potential for monitoring soil quantity rather than soil quality. LCM 2000 is an example that might be used to demonstrate this potential.
• Agricultural Census data. Table 8.1 above has been derived from these data, but considerable doubt has been cast on their accuracy in England and Wales (Sinclair 1992). Adjustments were necessary to provide categories for earlier years and to offset the effects of definitional changes and the report contends that the official figures fails to record the urbanisation of 180,000 ha of land between 1945 and 1990.
• The Scottish Vacant and Derelict Land Survey.

Data on peat extraction appears to be equally fragmented and in 2004, in response to a question asked in parliament on how much peat is extracted annually from peat extraction sites, the minister Ross Finnie indicated that this information is not held centrally. In 1988, ( MLURI 1993), approximately 30 km ² of peat was being actively harvested on a commercial basis. However this is much smaller than the 500 km ² that is being used on a domestic scale throughout the crofting counties. Unlike traditional hand cutting for domestic use, modern commercial peat extraction is large scale and mechanised and can present a significant conflict with nature conservation and archaeological interests. Under the EC Habitats Directive ( CEC 1994), active raised and blanket bogs are classed as "priority habitats", which means that a selection of pristine examples are designated as Special Areas of Conservation ( SACs). Sites thus designated will not normally be acceptable for development.

Given the recent findings on reductions in soil organic matter levels (Chapter 2) and role that Scotland's organic soils could potentially play climate change (Chapter 3), it is recommended that data on peat extraction be collected centrally by the Scottish Executive. Peat extraction contributes vitally both economically ( e.g. to the whisky industry) and socially ( e.g. to the crofting community), so a ban on peat extraction is both undesirable and unacceptable. However it is important that extraction be carried out with great care to ensure that environmental impacts are minimised.

Since the demise of deep mining, opencast coalmining is an activity that has grown over the last 15-20 years. Better information is available on the extent of opencast coal sites compared to development (Table 8.2).

Table 8.2 Areas (ha) of derelict and non-derelict land approved for opencast coal mining

* not differentiated
Source: Planning Officers Society, reproduced in Chapman et al., 2001.

These figures do not indicate whether the areas outlined have actually been exploited in full, but they are useful for indicating the scale of the issue. Information on the location of these sites is not collected centrally, but is held by the relevant planning authority. Planning guidance is given within Scottish Planning Guidance guideline SPP 16 (Scottish Executive 2005 http://www.scotland.gov.uk/Publications/2005/07/13111617/16198). Protection of soil is not explicitly covered although there is a section on restoration, after care and after use and a recommendation that PAN 64 'Reclamation of surface mineral workings' (Scottish Executive 2002 http://www.scotland.gov.uk/Publications/2003/01/16122/16256) should be followed. Of particular interest is the section on agricultural land that indicates that 'prime quality agricultural land should normally be protected against permanent development or irreversible damage'. This appears counter to policy changes specifically on the protection of agricultural land discussed above.

More recent data on approvals for opencast coal sites can be found at: http://www.bgs.ac.uk/mineralsuk/minequar/coal/occ/home.html

8.4.3. Gaps in data / evidence

The data presented above are at the national level and although useful for indicating the scale of the issue at this level, it provides no indication of where it is occurring, the quality and type of soil that is being displaced and the range of functions that those soils were performing. This type of information is captured, but is less easily accessible than previously (M. Johnstone, pers. comm.). A request was made to SEERAD to obtain some of this more detailed information but on closer examination, the data were not in a form that was readily useable or interpretable.

Data on the quality of agricultural land that became developed were routinely captured and presented during the 1970s and 1980s (Davidson, 1992) approximately half was prime agricultural land (Figure 8.1). Prime agricultural land however represents only 7% of the total land area of Scotland. There was a marked decrease in new development during the first half of the 1980s (500-600 ha yr ^-1) from that during the 1970s (1000-1,200 ha yr ^-1). This trend has been reversed in recent years and rates of loss of land to development are now at the levels of the early 1970s. Figure 8.1 also demonstrates the reduction in quality of information with no indication on the type of land that is being lost.

Figure 8.1. Loss of prime agricultural land from 1971-1985 (Davidson 1992) and of loss of undifferentiated agricultural land in Scotland from 1989-2003 (Table 8.1).

A study was conducted for Angus Council to examine how their current and proposed Local Plans would address both Central and local government objectives of sustainable development, soil protection and of sustainable agricultural production (Project Management Scotland Ltd 2004). Land quality, based on the Land Capability for Agriculture classification, was determined for those areas identified for potential development with the Local Plans. In the current local plan (up to 2006), 37.4% of the total area allocated for built or irreversible development is prime agricultural land, whilst in the proposed local plan, this rises to 62.7%. The report concludes that local delivery of central government objectives is particularly difficult in areas such as Angus where most of the towns are surrounded by an agricultural hinterland of predominantly agricultural land. This tension is likely to be replicated throughout much of the eastern lowlands of Scotland and even in the west, where prime land is much scarcer because of climatic constraints, some development is likely to take place on the better soils. This study (Project Management Scotland Ltd 2004) provides a valuable contribution to the debate on land development vis-à-vis soil protection, but is flawed where it makes the assumption that land lost to development is proportional across all land classes; this assumption leads to a serious underestimate of prime land loss and an overestimate of losses of the poorer quality LCA classes.

In the absence of localised data that explicitly identifies the quality of land being developed, Fife was used as a trial area to test whether different ages of digital data could be used to identify and characterise land lost to development. It was based on the hypothesis that the area of built-up land indicated on the various datasets would increase in size through time. To test this, the 1: 25,000 soil data (the mid 1960s), the 1: 25,000 scale LCA data (the early 1980s) and the 1: 25,000 scale LCS88 data ( MLURI 1988) were examined within a GIS. The experiment was only partly successful, in that the definition of built up land and the accuracy of their depiction on each dataset varied. It did not prove possible to determine the LCA class of much of the developed land, but there was a 31 km ² (37.5%) increase in built up area between the oldest and most recent dataset and the soils that have been replaced could be identified. The LCA class and the overall functionality of these soils could be determined retrospectively, and although it is beyond the scope and timescale of this project, it is an option for future study.

8.5 Conclusions

• Data on the loss of land and soil to sealing (development) is not collected in a consistent manner either at the national or regional level.
• Based on the limited information available, land appears to be being developed at a higher rate than at any time during the last 50 years; this raises questions of the sustainable use of resources and whether soil is being recognised and protected by the planning system.
• Soil lost to development is unable to fulfil any of its other functions; some such as biomass production is almost eliminated.
• There should be encouragement to re-use the soil that is removed during the construction phase.
• Based on previous data, a disproportionate area of our good quality and most flexible soils are lost to development ( LCA classes 1, 2 and 3.1); many of Scotland's settlements are located next to the best land within that area. As new developments tend to 'grow' from existing urban areas, this trend is likely to continue.
• It is recommended that data on peat extraction be collected centrally by the Scottish Executive.
• It is recommended that mechanisms be set in place that captures data on land and soil loss to development. In addition to location and area, information on soil type and quality should also be recorded.

8.6 References

Bibby J S, Douglas H A, Thomasson A J and Robertson J S (1991) Land Capability Classification for Agriculture. Macaulay Land Use Research Institute Craigiebuckler Aberdeen.

Birnie R, Curran J, MacDonald E C, Mackey C 2002 The Land Resources of Scotland: trends and prospects for the environment and natural heritage. The State of Scotland's Environment and Natural Heritage (eds Usher, Mackey and Curran) pp 41-81. The Stationery Office Edinburgh 2002.

CEH 2002 Critical Appraisal of State and Pressures and controls on the Sustainable Use of Soils in Wales. Contract report to EA/National Assembly for Wales

Davidson D A 1992 The Evaluation of Land Resources. Longman Scientific, London.

Chapman, S.J., Towers, W., Williams, B.L., Coull, M.C. and Paterson, E. (2001) Review of the contribution to climate change of organic soils under different land uses. Environment Group Research Programme Research Findings No.17. Scottish Executive Central Research Unit.

CEC (1994) Council Directive 92/43/EEC on the Conservation of natural habitats and of wild fauna and flora

Fuller, R.M., Cox, R., Clarke, R., Rothery, P., Hill, R.A., Smith, G,M., Thomson, A.,G., Brown., N.J., Howard, D., & Stott, A. (2005) The UK Land Cover Map 2000: planning, construction and calibration of a user-oriented map of Broad Habitats from remotely sensed satellite images. International Journal of Applied Earth Observation and Geoinformation, 7, 202-216.

Haines-Young, R.H. et al (2000) Accounting for nature: assessing habitats in the UK countryside, DETR, London ISBN 1 85112 460 8

Macaulay Land Use Research Institute (1993). The Land Cover of Scotland 1988 ( LCS 88). The Macaulay Land Use Research Institute, Aberdeen.

Prelier S (2005) Built up and associated land increases in Europe. International Institute for Applied Systems Research, Austria .

Project Management Scotland Ltd (2004) Local Authority Implementation of Scottish Government Policy. Soil Quality. Project report for Angus Council

Town and Country Planning (Scotland) Act 1997 The Stationery Office Limited.

Scottish Executive (2005). Choosing our future. Scotland's sustainable development strategy. Scottish Executive, Edinburgh 2005. http://www.scotland.gov.uk/Publications/2005/12/1493902/39032
(accessed 5 ^th September 2006)

Scottish Executive (2006) Scottish Planning Policy: SPP 11: Physical Activity and Open Space Consultation Draft

Sinclair S (1992) The Lost Land. Land Use Change in England 1945-1990. A report to the Council for the Protection of Rural England.

Wood G A, Loveland P J and Kibblewhite M. G. (2004) The Use of Remote Sensing to deliver soil monitoring Report prepared for DEFRA.

http://www.scotland.gov.uk/Topics/Planning/AdviceGuidance/PANs
(accessed 5 ^th September 2006)

http://www.scotland.gov.uk/Resource/Doc/83958/0036126.pdf
(accessed 5 ^th September 2006)

http://www.snh.org.uk/strategy/Landcover/results/built.asp
(accessed 5 ^th September 2006)

http://www.scotland.gov.uk/library/stat-ses/sest2-1.htm
(accessed 5 ^th September 2006)

( http://www.snh.org.uk/strategy/Landcover/method.asp)
(accessed 5 ^th September 2006)

http://www.scotland.gov.uk/Publications/2005/06/2290402/05121
(accessed 5 ^th September 2006)

http://www.scotland.gov.uk/Publications/2004/12/20392/48569
(accessed 5 ^th September 2006)

http://www.scotland.gov.uk/Publications/2005/07/13111617/16198.
(accessed 5 ^th September 2006)

http://www.scotland.gov.uk/Publications/2003/01/16122/16256
(accessed 5 ^th September 2006)

http://www.bgs.ac.uk/mineralsuk/minequar/coal/occ/home.html
(accessed 5 ^th September 2006)

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