Information and Advisory Note Number 50 Back to menu
Waste heaps (bings1) arising from mineral workings form an important and visible
part of the landscape of central Scotland. A link to the area's industrial past,
their reclamation over the last three decades has often been seen as tangible
evidence of the cleaning and greening of central Scotland. There is, however, an
increasing awareness that the unique environments which bings provide can have
considerable value as a wildlife habitat, landscape feature or recreation
resource. This information and Advisory Note therefore provides a review of
recent research on the heritage value of bings and provides advice on factors
which should be considered prior to any reclamation.
In Scotland, the main type of bing is coal spoil from deep mining although other
wastes such as spent oil shale, ironstone, slags, metal ore waste and lime
wastes do occur. While bings can have negative environmental impacts in terms of
visual intrusion and contamination of land and water courses, they can also be
of nature conservation interest because of their highly distinctive environments
(e.g. acidic, nutrient poor, high heavy metal content). Many bings have been
reclaimed over the past twenty years. While there is an increasing recognition
that they can often support distinct vegetation or rare species worthy of
protection, the process of reclamation or restoration continues, albeit at a
slower rate.
1 Bing is a Scots word meaning to heap or pile up but it is also used to
describe a slag heap.
Five Sisters, West Lothian (Photo: Lorne Gill, SNH)
In 1993, Scottish Natural Heritage commissioned the Centre for Research in
Environmental Science (CREST) at Glasgow University to undertake a study
entitled" The natural heritage interest of bings (waste ops) in Scotland:
inventory and review* to provide a comprehensive background to the issues
relating to bings in Scotland. The three principal aims were:
1. to draw together existing knowledge of basic site information on Scotland's
bings in the form of a database;
2. to undertake a physical survey of a sample of 30 bings; and
3. to conduct a questionnaire to appraise local community perceptions of
selected bings.
This Information and Advisory Note provides a summary of the CREST report. The
full report (Allan et al., 1996) and the accompanying PC based database of
surveyed bings is held at SNH HQ Library in Edinburgh and Regional offices. The
database is currently being developed by the Landscape and Restoration Branch in
the Research and Advisory Services Directorate.
Mining waste is comprised of two components:
2.1 Coal mine waste
Coal mine waste, the waste which has been produced in Scotland for the longest
period, became a serious issue following the introduction of mechanised mining
during the period 1870-1920. Mechanised mining resulted in more waste being
brought to the surface resulting in the formation of bigger, higher, generally
more loosely packed bings. The resulting problems of spontaneous combustion and
instability (which contributed to the Aberfan disaster in 1966) led to changes
in regulations to ensure that bings were more tightly compacted and not as high.
Most of the mining activity in Scotland has been confined to the Midland Valley
(e.g., Strathclyde Central, Fife and Lothian) and this is consequently the main
location for mining wastes.
Coal production in Scotland, which peaked in 1913 at some 43.2 million tonnes,
has declined consistently since the Second World War until by 1993 there were
only two deep mines operating in Scotland. While there has recently been a
significant increase in open cast mining this does not produce a waste
bing as the unwanted substrate and soil cover have to be replaced as an
extraction license condition. As a consequence of this change in the pattern of
Scottish coal mining, the bings which still exist are now in the main relatively
old and their number is not significantly increasing.
2.2 Oil shale mining
Oil shale mining was centred upon West Lothian and Midlothian with small
adjacent areas in Lanarkshire and Fife. The main products of the industry were
crude oil which could be fractionally distilled to produce naphtha, burning oil,
cleaning oil and lubricating oil as well as ammonia. Production peaked in 1913
at 3.25 million tonnes and oil shale extraction ended in 1962 as other source
materials emerged and the seams were worked out. The large bings near Broxburn
seen from the M9 and M8 are evidence of the legacy of this industry.
2.3 Ironstone mining
A source of bing material, ironstone mining for use in the iron smelting
industry was centred around the Lanarkshire/West Lothian area. The industry
peaked in the 1880s with outputs rapidly declining due to the exhaustion of the
richest and most accessible seams. Ironstone mining no longer occurs in
Scotland.
The legacy of mining and extraction has in part contributed to the high level of vacant and derelict land in central Scotland. The Scottish Vacant and Derelict Land Survey 1990 recorded 8297 ha. of derelict land and 3844 of vacant land in Scotland. Eighty three per cent of this was found in Strathclyde, Lothian, Central and Fife Regions. Land previously used for mineral extraction accounted for 35% of the total area of derelict land in Scotland. This percentage is higher than the comparable figure for England.
Bing reclamation often takes place for a number of reasons:
Bing reclamation in the form of earth moving operations to provide stability,
making them less obtrusive and providing a basis for agricultural re-use, has
therefore been common practice over the last four decades. During reclamation,
fertilisers, lime and organic matter to aid plant growth are usually added.
Until recently the principal after use was for agricultural production which
required a high input of nitrogen and phosphorus. However, in recent years, as
the demand for agricultural land has decreased, other plant covers which provide
an amenity value have become common.
Comprehensive bing reclamation has taken place throughout Scotland. While most
bings have been returned to agricultural production there are also recreational
developments at Newtongrange and Kilwinning, and golf courses, for instance at
Polkemmet and Loch Ore and Cowdenbeath in Fife. Unreclaimed sites by contrast
often have no planned use existing simply as derelict land used frequently for
fly tipping, casual recreation by local communities or removed gradually for
engineering purposes. Existing bings are often emotive and occasionally
unwelcome reminders of the harsh conditions in the mining industry which
employed many people in Central Scotland in the latter half of the 19th and
first half of the 20th centuries.
Although many bings in central Scotland have been removed for reasons of
landscape amenity, safety, economic necessity and/or
political will, there has been a gradual realisation that they represent
interesting and potentially unique habitats which can, with time, develop into a
valuable natural heritage resource.
The nature conservation importance of bings lies in the fact that they often
represent small pockets of a highly distinctive environment, thus providing
specialised ecological niches. For this reason bings may be worthy of
protection. Many old sites which have been colonised naturally show interesting
botanical features and may also be important habitats for wildlife.
Bings may also have an earth science interest in that some may show evidence of
soil formation. The waste material in a bing is essentially crushed rock which
may be considered as a soil parent material. This, combined with the known age
and history of most bings and any natural vegetation which has become
established, could provide a useful study site for the processes which act on
rock to begin soil formation.
Over the past 25 years, a number of studies, both in the UK and abroad, have
dealt specifically with the nature of the substrate in bings (particularly coal
waste) and its influence on the development of particular habitats. A
comprehensive bibliography is included in the full report by CREST.
Once dumped in a bing, the shale is subjected to natural weathering processes.
The most rapid breakdown of the shale occurs in the first 20 years. The extent
of weathering and hence the dominant particle size influences other properties
of the waste. On slopes where large pieces of shale predominate, the unstable
nature of the waste leads to erosion and creep. Both processes result in the
deposition of waste at the base of slopes which can in turn affect the
topography and hence ecological niche properties of a bing.
The chemical properties of waste materials in bings can have two consequences:
The central factor which affects the chemical properties of substrates is spoil
pH. While
colliery spoil has a fairly neutral pH of 7 to 8 when tipped, leaching by water
starts the process of the loss of exchangeable bases (calcium, magnesium,
potassium and sodium) If the shale is rapidly weathered, sufficient amounts of
exchangeable bases may be released to maintain only a slightly acidic pH.
However, if the weathering is stow, leaching of exchangeable bases can proceed
rapidly due to the open nature of the spoil and low cation exchange capacity. On
such sites, pH values of 4.5 to 5.5 are common. Thus the acidifying effects of
the leaching of bings can lead to moderately acidic conditions and is a process
analogous to that occurring in some natural soils in Scotland. A further factor
which leads to reduced pH is the presence of pyrites (iron pyrites FeS2) which
can produce pH values of 3 or less. The presence of pyrites can lead to loss of
vegetation, n increase in soluble heavy metals and the acidification of mine
drainage.
On sites such as coal and oil shale bings, the substrate for plant growth is
primarily mineral, with very little development of organic matter until
significant amounts of vegetation have become established. The spoil usually has
a low nitrogen content and the lack of organic matter means that the main
storage reservoir for nitrogen fixing is missing. Other nutrients such as
phosphorus, calcium, magnesium, potassium and sulphur are usually found in large
amounts in the substrate, but the problem is generally with their availability:
a factor which depends on the rate of weathering of the spoil, the pH and the
degree of leaching. Add spoils tend to be more deficient in these elements than
spoils with neutral or slightly alkaline pH.
Given the wide range of types of bing, nutritional properties can vary
considerably. Thus a great variety of plants may establish on bings ranging from
nutrient rich on wastes such as slag to nutrient poor on acidic colliery spoil,
oil shale and slate wastes.
There have been a number of studies which have examined plant succession on mine
waste bings and the difficulties of correlating plant community succession with
the age (since abandonment) of mine waste tips. Given that bings are often not
of a uniform age and will have often been disturbed as a result of tipping, coal
scavenging or unlicensed tipping, they are more likely to support a mosaic of
plant communities of differing successions! age than a single
vegetation type A basic typography was proposed by Hall (1956):
The floristic interest of bings in Scotland was first identified in the 1960s with discoveries of the club moss Lycopsida, the moss Bryopsida and the nationally rare moss, Buxbaumia aphylla. Further work on the bings in and around Glasgow in the 1980s revealed a number of coal bing plants of high conservation interest including:
Other bing discoveries include the rare grass viviparous sheep's fescue,
(Festuca vivipara), the rare mosses Rhytidium rugosum, Entodon condnnus and
Ditrichum plumbicola, which was described as new to science by Crundwell (1976)
from lead bings in England, Wales and the Isle of Man and was found on spoil at
Tyndrum (Hill, 1980).
Despite these discoveries, the flora of bings is still only partially known. The
faunal interest of bings has also been largely ignored although bings clearly
function as important wildlife corridors. What evidence there is relates to
easily observed and "popular" animals such as badgers, foxes and rabbits.
The study of Scottish bings by CREST obtained data from Regional and District Authorities in addition to the Vacant and Derelict Land Survey. Where possible, sites identified initially from maps were confirmed from other sources and both reclaimed and unreclaimed sites were identified. In total 560 sites (over 1 ha. in size were identified with another 283 unconfirmed. These include both reclaimed and unreclaimed sites. Lanarkshire has the greatest number of bings: 217 confirmed, plus 154 unconfirmed. These are concentrated in Monklands, Motherwell and Hamilton Districts. The survey highlighted the considerable lack of information about many sites. For example, information on flora is patchy while data on fauna is virtually nonexistent.
It was not possible to survey all 560 bings in central Scotland as part of the
project. Instead, a random sample of 30 bings representing a spread of
geography, attributes etc. were surveyed during June - August 1993. Data on
physical characteristics, vegetation and substrate were assessed. The physical
attributes of each bing comprised six habitat categories (e.g. physical features
such as ridge or steep gradients) and four aspect categories (e.g. orientation),
while vegetation was recorded within 11 separate categories (e.g. bare ground,
tall herb, planted woodland etc.). Substrate attributes included pH plus other
factors such as particle size, stability evidence of organic material etc.
The main conclusions were:
1. In general terms the bings surveyed tended to have a slightly greater
tendency to be oriented east-west rather than north-south.
2. The most important habitat features are summit ridges and steep slopes
although there is considerable variability across the data set.
3. Substrate pH was quantified as being an easily measured and useful means of
categorising soil conditions for plant growth. Three broad categories were
identified <pH 5.5; pH 5.6-7.4; >pH 7.5. Very acidic conditions develop where
pyrite is present in the spoil is common in
Lothian, parts of Ayrshire and southern Lanarkshire. Neutral to acidic pH values
were common on oil shale bings, and coal bings in Glasgow, western Strathclyde
and in Central Region. The most acidic conditions were found on summit ridges
and steep slopes while the least acidic were found in summit hollows and the
bing surrounds. The range of pH recorded across the sample was, however, very
large.
4. TWINSPAN classification (a means of
objectively classifying complex data) of the
30 survey sites in terms of whole site
vegetation suggested that several main
groups, relating broadly to pH could be
identified:
5. Generalisations about differences between bing site-groups do, however,
obscure the substantial within-site variability. Clearer differences in soil pH
and flora existed between site-groups when summit or slope habitats were
compared, than when bing surrounds were included in the comparison.
6. Bare ground and grassland (gappy or closed turf) predominate throughout the
sample, with the poorest cover of vegetation being on summit ridge and steep
slope habitats. These areas may have substantial nature conservation interest,
including locally rare or
uncommon species, and some support nationally rare taxa.
7. Scrub and woodland vegetation were the second most commonly encountered
vegetation types. The study team did not consider it possible to draw any
meaningful conclusions on rates of vegetation succession to woodland on bings
because of the unquantifiable influence of disturbance events during the history
of a bing; the importance of site-specific factors in influencing rates of
succession; and the mosaic nature of most bing habitats, which greatly increases
the discrepancies within the existing data.
8. Bing vegetation is perhaps most strongly influenced by substrate conditions,
although climatic and other factors are also of course relevant. Vegetation data
provide a reasonably good basis for classifying bings because the plants present
at a bing integrate the full set of environmental factors influencing the
habitat.
In addition to the survey of environmental attributes, five bings were chosen for an additional study of the attitudes of local residents. The survey was designed to identify the opinions of local people on the visual quality, use and perception of bing sites as well as possible future strategies for natural heritage use. Five communities living within one kilometre of bings at Cadzow near Hamilton, Dewshill in Lanarkshire, Newton near Glasgow, Lothian bridge in Midlothian and Dalmellington in Ayrshire were surveyed. The sampling of households was random although the surveyors did divide the questionnaires on the basis of perceived housing tenure (owner occupied and council housing) to gain an understanding of the issues across socio-economic grouping and highlight households with different views of and access to the bing. In total, 122 households were surveyed by means of a face to face interview. The questionnaire was designed to address:
In summary:
1. Most local residents appear to be at least satisfied with the visual quality
of the bings in their current form (see Figure 1 below) although much lower
levels of satisfaction were recorded at Dewshill and Dalmellington reflecting
the relatively recent mining history and the obtrusive nature of the bings. The
highest levels of satisfaction were recorded at Cadzow where the bing is heavily
wooded.
2. The large majority of local residents held the view that bings should be
maintained and landscaped to form part of the continuing landscape.
3. A minority felt that bings are an unwelcome reminder of the past, that they
intrude on the life of the community and that they should be removed completely.
4. Only a third of respondents made use of the bing for informal recreation
reflecting, in part, issues of safety and difficulties with access.
5. The majority of respondents considered that the nature conservation interest
related to the faunal aspect and were unaware of the botanical or
geomorphological significance of the site. This is significant in view of the
existence of nationally important species on a number of sites.
6. In terms of future management, most respondents considered that the main aims
should be to improve the quality of the landscape and to utilise it for some
educational or recreational purpose. Creation of a tree cover and regular
tidying
of sites were considered to be important aspects of management. There was little
support for extensive earthworks to change the shape of bings although at
Dalmellington and Dewshill there was some support for the complete removal of
the bing, reflecting the perceptions of the local communities of both poor
visual amenity and site maintenance.
7. The majority of respondents considered that site access should be improved,
for example, by the provision of maintained footpaths and local information.
Increased access should be accompanied by a safety policy for such sites.
In recent years there has been a considerable amount of bing reclamation,
particularly in urban areas and on the urban fringe. This has generally been
undertaken for good reason reflecting the fact that bings often represent safety
hazards, can result in pollution to air land and water On the form of dust) and
are frequently considered unattractive. However, a number of factors should be
considered when a bing, which may be perceived to have natural heritage value,
is scheduled for reclamation:
1. Is the site safe? If not, can it be made safe?
2. What features of a bing are of natural heritage value worthy of protection?
Are they unique/rare/common? If so:
3. Is it essential to retain the whole bing to protect the natural heritage
interest?
4. Will earth moving operations and/or application of amendments, change the
important habitat or environmental features of the bing?
5. Can the natural heritage aspects of the existing bing be incorporated into
the landscape design for the reclaimed site?
6. Are there any opportunities to create natural heritage interest on a
reclaimed bing, for example, by creation of an artificial wetland habitat?
7. Are there any educational opportunities to use a site because of its
industrial heritage or habitat/nature conservation value?
The study highlights the need for careful consideration to be given to any bing
reclamation proposals to ensure that the distinctive and potentially unique
natural heritage interest is adequately considered.
Allan, R.L, Dickinson, G., Dickson, J.H., Duncan, H.J., Murphy, K.J., Pulford,
I.D., Rogerson, R. and Watson, K. The natural heritage interest of waste tips
(bings) in Scotland: inventory and review. SNH Review No. 48, SNH, Battleby.
Crundwell, A.C., (1976). Ditrichum plumbticola, a new species from lead mine
waste. Journal of Bryology,_9,167-169.
Hall, I.G. (1957) The Ecology of disused pit heaps in England Journal of
Ecology, 45 689-720.
Hill, M.O., (1980) Musci. Bulletin of the British Bryological Society, 36,
32-49.
Dickson J.H. (1990). Conservation and the botany of bings. Transactions of the
Botanical Society of Edinburgh, 45,493-500.
Jobling. J., (1987). Reclamation - colliery spoil. Forestry Commission Bulletin
65, HMSO.
Palmer JP., & Chadwick, M.J., (1985). Factors affecting the accumulation of
nitrogen in colliery spoil. Journal of Applied Ecology 22, 249-257.
Fraser Mackenzie,
Landscape and Restoration Branch,
Research and Advisory
Services Directorate,
Scottish Natural Heritage
Centre for Environmental Science and Technology
University of Glasgow
GLASGOW
G12 8QQ
Urban Conservation Officer
Landscape and Restoration Branch
Research and Advisory Services Directorate
Scottish Natural Heritage
2 Anderson Place
EDINBURGH
EH6 5NP
Tel 0131-446 2465