326 CONFERENCE ON NATURAL BEAUTY 



percent of all strip mining, iron ore, sand, gravel, and clay being 

 responsible for the balance of the 200 million tons of mineral pro- 

 duced annually from surface mining. 



With regard to the deep mining of coal, it has been possible to 

 mitigate any surface damage caused by subsidence, in some cases 

 by back-filling underground, and also by what we call harmonic 

 extraction of the coal seams which so limits the stresses set up in 

 surface buildings that damage is obviated despite a lowering of the 

 surface. Special structural precautions are normally taken with 

 new buildings on land liable to mining subsidence. 



Work is also proceeding to eliminate the ugliness of waste dumps. 

 Some of the material is used for brickmaking and vast quantities 

 have been removed for the construction of new motorways. We are 

 now contemplating the use of this waste material for the manufacture 

 of aggregate used in concrete constructions. Where it is not possible 

 to utilize the waste material, much work is being done in contouring 

 the dumps in conformity with the surrounding countryside. Experi- 

 ments are in hand for planting the contoured dumps with suitable 

 trees. 



In strip mining the land has always been completely restored ever 

 since this form of coal mining was started in 1942. This not only 

 involves filling the final void, which can sometimes be extremely 

 expensive, but we have to strip and segregate subsoil and topsoil. 

 When the site has been regraded and the soil replaced, fences are 

 erected, ditches are dug, and the land is then given a 5 -year course 

 of agricultural rehabilitation by the Ministry of Agriculture on behalf 

 of the National Coal Board. This includes intensive fertilization 

 and the installation of tile drainage. The average cost of this restora- 

 tion, excluding the filling of the final void, is in the order of $1 per 

 ton of coal extracted. This may well seem high to my mining friends 

 in the U.S.A., but even after meeting this cost we still manage to 

 make a profit of about $2 per ton on our strip-mined coal. 



In an endeavor to improve our restoration even further and to 

 enable us to screen our operations from view when working close 

 to housing or major roads, we have in the past two years been using 

 mechanical equipment designed and developed in the United States 

 of America for transplanting semi -mature trees. (We are par- 

 ticularly indebted to the Civic Trust who pioneered semi-mature 

 tree transplanting in Great Britain and to the authorities of the Mor- 

 ton Arboretum near Chicago for the know-how of the system.) 



