IMPROVEMENT OF ENVIRONMENT AND ECOLOGY IN MINES
RECLAIMATION OF LAND
By
Saifuddin Saifee, M.I.E. (Mines)
Mining Engineer (Plan)
Mines Department, Secretariate, Ja ipur.
According to Prof. B. B. Dhar of Banaras Hindu University "the-environmental problems
are increasing with increase of mineral exploitation. Every mining project should now
introduce an environmental assessment and management plan at initial stage of mining."
Rajasthan State has made progress in the field of mineral industries during last two
decades. The State produces nearly 60 minerals including minor minerals. These playa
vital role in the economic main stream of the state. All the minerals except base metals
(Pb., Zn. & Cu, etc.) are raised from open cast mines. The important minerals are
limestone, gypsum, rockphosphate, marble, soapstone, sandstone, calcite, dolomite,
silicasand, garnet, mica, barytes, clays etc. with the increasing industrialisation the
demand is also increasing year by year. The State Mines & Geology Department is
planning to exploit lignite deposits which is the main resource of the energy and boost the
growth of industrialisation. Mis. OIL and ONGC are making their efforts to assess the
reserves of petrol and natural gases in Jaisalmer, Barmer and part of Bikaner/Nagour
areas. This will also help in meeting the increasing demand for energy.
In Rajasthan number of mines has increased from 1870 in 1960 to 25663 in 1986.
* Table below shows trend of mining leases in Rajasthan from which most of the
minerals are produced by opencast mining methods :
Year
MINING LEASES
Total
Major Minerals
Minor Minerals
Leases
Leases
Quarry Licence
1960
1965
1970
1975
1986
500
680
800
1315
1900
800
1050
1400
4035
6783
570
8025
8750
15000
16980
1870
9755
10770
20350
25663
* The following areas were granted llnder mining leases during 1970, 1980, 1985 ;
Areas given under Mining Leases
(in Sq. Km.)
Year
Major Leases
Minor Leases
Quarry Licence
Total area
1970
965 25
28.00
15.50
1008.75
1980
2005.50
80.70
27.00
2113.22
1985
3125.00
116 00
29.00
3270 00
Note: It is further likely to go up by the end of this Century.
The opencast mining results in a constant decline of cultivated and green areas as it
involves the removal of surface soil, overburden, etc. to excavate the mineral deposits
lying under the surface of the earth. It disturbs the surface land consisting of different
layers of soils which maintains ecological balance. The entire eco system is changed due
to the excavation of the land. This causes deforestation further resulting in soil erosion,
land subsidence, flooding etc. Air, water and noise puJlutions are associated with
exploitation of the minerals from opencast as well as underground mines. Therefore, it
becomes imperative to reduce this demage and to restore the excavated land to the almost
in original state.
Recently the Central and all State as well as Union Territory Govts. have paid
attention to environment planning and are making efforts for environmental
consciousness among the people so that they may counter the attempts to pollute the
environment, to deforest and destroy the forest growth, and disfigure the natural surroundings. The increasing demand of the minerals is aggrandizing the need of environmental
planning in future.
ENVIRONMENTAL POLLUTION IN OPENCAST MINES.
The environmental pollution in the context of opencast mining can be divided into
the different categories mentioned below ;
1. Land Degradation.
2. Air Pollution.
3. Water Pollution.
4. Noise Pollution.
5. Ecological Pollution.
6. Others such as damages due to heavy blasting and Socio-economic changes, etc.
1. LAND DEGRADATION:
Excavation of land in surface mining changes the landscope which creates voids
due to removal of mineral and overburdens. The waste overburden and tailings are most
of the time thrown, spread over large areas and effeet"1he scenic beauty of the land and
such overburden also causes deterioration of aesthetic values. The land degradation is
mainly due to opencast workings whicn causes land slides.
To control the land degradation due to mining, the followings should be kept in
mind while mining the minerals by open cast workings:
i) Prompt removal of dust from different sources.
i i) Spreading of frequent water on the haul roads in the mines.
iii) Dumpers which are main causes of dust formation on the haul roads, should be
replaced by belt conveyor. Dumpers also generate a lot of exhaust gases which may be a
problem particularly when workings are at deeper places.
iv) Plantation in & around the mine and along the road sides in mining areas should be
made. This serves as good dust arrestor.
v) Collection of Mine Water in an artificial pounds or sinks and use of this water after
proper treatment.
vi) Dumping should be systamatic so that the top soil layer is not disturbed.
vii) By adopting reclamation, the mined out area can be made suitable for forestry.
2. AIR POLLUTION:
There are two causes for this pollution :
a) Emission of dust particles to atmosphere,
b) Addition of gaseous pollutants.
Various mining operations generates dust which causes health hazards due to
inhalation and diseases like pneumaconosis, silicosis, etc.
Gases like Carbon-di-oxide(COz ),Carbon monoxide (CO), Sulphur-di-oxide
(SOz). etc. pollute the air. These gases are produced during blasting, operation of various
equipment at the mines and factories near mines as well as town. Air Pollution is clearly
visible near cement factory, soapstone grinding units, crushers, etc.
3. WATER POLLUTION:
Discharge of mine acid water is the main cause of Water Pollution. Lowering of
water table in mines changes the hydrodynamic conditions of underground recharge
basins and subsurface drainage system. Surface mining considerably lowers down the
water level.
4. NOISE POLLUTION:
Heavy earth moving machineries, mobile and stationary plants operating at the
mines drilling and blasting are the major sources of highly intensified noise in Mining
Industries which is harmful for humans may cause permanent deafness. Higher noise for
shorter intervals can be safer but for huge duration. or for a continuous noisy shift it
becomes very serious and cause health problems.
5. ECOLOGICAL POLLUTION:
Development of a pit for exploitation of mineral deposits which are generally
located in forest, destroys trees and vegetation and gives an ugly look to the area due to
throwing of overburden and mine dirts nearby the pit. Regular destroying of trees and
vegitations changes the condition of climate. Due to this, rainfall, temperature and
humidity of the area are effected and results in disappearance of wild life.
6. Others such as damages due to heavy blasting and Socioeconomic changes, etc. :
Sociological and Cultural aspects relate to environmental effects of opencast
mining due to which pollution of drinking water, air, reduction of fertility of agricultural
lands, etc.
LAND RECLAMATION:
The present society is paying attention towards the surface lands which were
disturbed and damaged due to hectic mining activities. To check this damage, proper
measure should be taken to reclaim the abandoned mining lands and to reuse it for
productive and recreational purposes, say for agricultural, forestory, etc. Land
reclamation is necessary to avoid accumulation of watar in worked out opencast mines.
Due to this, disfiguration of land scope caused by spreading overburden and mine dirt
would be avoided.
Reclamation planning should also be integrated with Mines Planning. The reclamation planning can be made in two stages:
i) Pre-mining use of land, and ii) Post-mining use of land.,
The actual success to reclaim the cite is in planning for post-mining land use. The
main points to implement successful reclamation planning are :
1) To ensure that the planning is suitable technically, economically Clnd socially.
2) To chalk out the flexibility of mining programme to achieve maximum and efficient
land reclamation.
3) To check the chemical and properties of the overburden.
4) To evaluate additional cost in relevelling and spreading of sub-soil and top soil and
also evaluate the hydrology of movement of water in the mine area.
HOW TO RECLAIM THE LAND
It depends on the depth and volume of overburden removed. The reclamation of
land are classified in categories below :
1) Deep pits with no overburden:
Such pits can be converted into lakes or ponds to store water which can be utilised
for forming or forestry, e.g. cru3hed stone quarries, gypsum mining etc.
2) Deep pits with ample overburden:
Mostly coal and nonferrous metal mines develop deep pits with ample overburden.
Such can be filled back for the development of forestry/farming.
3) Shalow pits without overburden:
The mining of minor minerals like grounds, building materials like sandstone,
limestone, marble and also small deposits at the surface like, asbestos, soapstone, calcite,
clays, silicasand, etc, is the cause of development of shallow pits The building mDterials
mining are nearer to the City or Town. If the mines are developed in better way, can be
converted into lakes, pounds and parks for very good recreational facilities.
4) Shallow pits with ample overburden:
Most of the minerals like iron, limestone, coal, lignite. rockphosphate, soapstone,
etc. came under this category. In such mining due to ample overburden. the reclaimed
land is mostly used for forming and social forestory.
All the previously worked pits are back fillen by overburden already removed and
then sub/top soil is despreaded over such refilled land by grading in planned contour
with the help of bulldozers, graders, scrapers, etc. Back filling can be made by shovel
and dumper, stripping shovel or dragline, bucket wheel excavator with sprea-. der, etc.
After completion of spreading top soil,' the biological reclamation commences to restore
fertility of the disturb land which further depends upon the depth and nature of top soil,
climate of the area, local socio-economic factors. Complete biological reclamation
generally takes around 5 years time to complete.
RECLAMATION COST:
This varies with the topography of the land and the purpose for which the land is
being used. The cost varies from about 25 to 45% cost of mining. The cost varies due to :
1) Preparation of ground system & 2) Drainage (3) Plantation.
The reclamation cost consists of :
a) Cost of removal of top-soil and dumping at separate site.
b) Chemical analysis of overburden from time to time.
c) Cost of back filling, spreading, levelling, grounding of sub-soil and top-soil.
d) Cost of plantation and fertilizers.
In case of Coal mines in India, this cost ranges between Rs. 2 to 5/- per tonne of
Coal produced.
Conclusions:
From the above it is evident that the impact of mineral mining on environment is
Inevitable. With the growth of mineral production, the environmental problems are also
growing up.
There would be much concern in future about the environmental pollution. Hence
the environ mentalists and policy planners should payattention seriously for protection
and improvement in environmental conditions by way of reclamation of mined area. For
this every mining project should prepare a requisite environmental assesment alongwith
the details of preparation of site, working of the site restoration of site or reclamation
methodology after completion of working, rehabilitation of plants, etc. Such an approach
is essential for effective land utilization in the mining industry for which the envolvement
of related departments, such as Mines, Forest, Revenue, Agriculture, Planning eto. is
essential.
Reference:
1) Mineral Statistics of Rajasthan, 1971-72
2) Mineral Statistics of Rajasthan, 1981-82
3) Mineral Statistics of Rajasthan, 1984-85
4) Prop. B. B. Dhar. Process of Improving Environment & Ecology: Journal of the
Institution of Engineers (I), VOl 67, Nov. 1986. P. 35.