British Coal Opencast is responsible to British Coal for the development, evaluation, planning and supervision of opencast coal mining operations in England, Scotland and Wales. By extracting coal from seams at shallow depth opencast mining helps to provide valuable fuel for the nation, earns profits for British Coal, offers imaginative restoration and the removal of industrial dereliction.

History

Opencast mining for coal as we know it today started in 1942 as a wartime expedient. To boost vitally needed coal output, surface mining became the responsibility of the Mines Department of the Board of Trade and was carried on by the Ministry of Works until 1945, then by the Ministry of Fuel and Power.

In 1952 the National Coal Board, now British Coal Corporation, was given responsibility for opencast coal production and the Opencast Executive was established.

In the early years opencast operations were limited by the size of the excavating plant then available. Maximum depths were only about 10 metres and ratios of strata above the seams — overburden — to coal were restricted to about 5 to 1. Over the years, however, there were substantial increases in the size of plant and by 1948 the maximum depth of excavation had increased to 30 metres. Today working depths of 80 metres are commonplace and the deepest excavation so far has been 215 metres at the former Westfield site in Scotland. The average overburden to coal ratio now is 18 to 1 with parts of some sites being worked up to 40 to 1.

The excavating plant of the early 1940s was limited to a bucket size of less than one cubic metre but today there are draglines with bucket capacities ranging from 10 to 27 cubic metres. The largest weighs 3,000 tonnes and can excavate 50 cubic metres with each cycle.

In 1990 the name of the Executive was changed to British Coal Opencast.

Production

In 1945 opencast coal production in Britain was about eight million tonnes a year. Throughout the next few years this figure was raised progressively until 14 million tonnes was reached in 1958.

For several years afterwards output was restricted owing to reduced demand and by 1968 annual tonnage was down to 6.5 million tonnes. From 1970 demand again improved and since deep mines could not provide all the coal required, opencast output increased to 9.1 million tonnes in 1974/5. In line with the Plan for Coal published in 1974, opencast production steadily increased so that in 1980/1 output reached 15 million tonnes for the first time. Since then annual production has been at about 14 to 17 million tonnes, and the Opencast plans to increase output to meet demand for low cost high quality fuel.

Site planning

Several years of investigation and preparation are necessary before work can begin on a new opencast coal site. Local authorities and other statutory bodies as well as landowners and others with an interest are consulted, so that working arrangements which will cause the least disturbance and make the best contribution to the future use of the land can be discussed. A full environment impact assessment precedes every planning operation.

Where possible land for new sites is purchased, as this provides maximum flexibility when planning restoration. However, temporary possession of the land, for the life of the site, can be obtained under the terms of a Working Rights Agreement negotiated with the occupier. Negotiations with landowners and occupiers are carried out by the District Valuer on behalf of British Coal.

As in the case with all mineral developments, planning permission to work opencast coal sites is sought from the Mineral Planning Authority. If this is refused a Public Inquiry may be held and the decision is then made by the Secretary of State for the Environment, Wales or Scotland as appropriate.

Once planning permission has been granted, tenders are invited from civil engineering contractors to prepare, work and restore the site.

Site operations

The large-scale multi-seam mining operations now undertaken, start with the topsoil and sub-soils being separately stripped and placed in baffle mounds around the site to screen the workings. The mounds are grassed and kept cut to improve their appearance.

An initial working void is excavated by a combination of excavating machines and ancillary plant and the excavated overburden material stored on the surface. Work then progresses in a series of cuts. As coal is exposed it is lifted by smaller excavating shovels and transported by road vehicles to a Disposal Point for sizing, screening and blending prior to sale to Power Stations, general industry or the domestic market. It is frequently used for blending with lower quality deep mined coal to improve quality.

Great care is taken to control and minimise problems of noise, dust, vibration from blasting, water pollution and visual impact. Large draglines are electrically powered and efficient silencers are fitted to diesel plant. Where blasting is necessary it is carried out at specific times and within strict safety limits recommended by independent experts to ensure there is no possibility of damage to surrounding property. Water bowsers spray internal haul roads to suppress dust. Settling ponds ensure that the quality of site water discharged to local watercourses meets the requirements of the Water Authority.

Restoration

The replacement of soils in sequence is followed by a five-year period of aftercare to rehabilitate the land for its planned future use, usually a return to agriculture. During this time fixtures such as hedges, fences, ditches, water supplies, shelter belts and woodlands are replaced and the land is cropped and managed by the Ministry of Agriculture. On higher grades of land there will be a mixed cereal and grassland rotation while the lower grades will be used for grazing or hay rotation and silage production. Except for upland areas of high rainfall and low land quality, restored areas have a permanent under-drainage system installed as early as possible often in the first year. Land is returned to its owner if it has been leased, or sold on the open market, once restoration is complete.

Because the extracted coal represents only a small proportion of the material removed, restoration is possible to original contours. Restoration after opencast coal mining can create opportunities for a change in land use, particularly on those sites where dereliction clearance has formed part of the mining operations. If land is not required for agricultural use it can provide infrastructure or recreational facilities in localities where these are in short supply. The land can he contoured and restored to specifications agreed with the local authority to provide a basis for a country park, nature reserve, golf course, sports field or other leisure uses. Alternatively the land can be prepared for industrial or residential development.

In recent years the efficiency of farming within the EEC has led to some over-production. As a consequence future restoration planning for opencast sites is likely to be directed to a more balanced land-use which takes into account a lessening emphasis on agriculture and an increasing emphasis on conservation, landscape renewal, recreation and redevelopment in urban areas.

Consultations take place before sites commence, to establish methods of preserving special areas of natural habitat, regenerating them during restoration or creating new areas attractive to wildlife.