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Use of Global Positioning System in coal mine surveying
A way-out is possible on these points:
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Initial high investment:
A cost of about Rs.15 to 16 lakhs may not be a debate at all in case of coal companys atleast those which are profit making.
- Accuracy:
Accuracy achieved by normal GPS is not absolutely useful for mine surveying, since what is spoken is about a single digit metre in horizontal and two-digit metre in vertical accuracy. But, methods are available to achieve a few mm. accuracy in both horizontal and vertical parameters. One of the systems of Survey using GPS is to establish a known station and carry out relative observations at other stations spread over certain period of time and get the relative position very accurately. A quadrilateral network for survey with reciprocal observations have proved very effective in achieving good results. All the vectors are measured very accurately, from which the angles between the vectors can be correctly worked out and rest is simple mathematics.
- System of Coordinates:
It may be true that GPS data is in WGS 84 coordinate system, which is different from our system. But, there are programs to calculate the position and height of points in the desired grid system through suitable translation software. We may choose desired software and overcome this problem by consulting experts on this subject.
- Need for clear view of sky:
A clear view of sky without any canopys is needed for working with GPS and hence, it is not suitable in underground mines. However, it can be used in Opencast projects, which are nowadays contributing very much for targets and profits particularly in coal sector. In case of underground mines, the surface base line can be established through GPS, which can be transferred to underground by conventional methods.
The possible fields of GPS application in mine surveying may be:
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Establishing National Grid bases at new areas:
National Grid bases can be established with the help of GPS in the new areas irrespective of their topography or distance from the central station duly established with known parameters.
- Establishing boundaries in case of mining lease areas:
In case of existing mining leases for renewal, latitude and longitudes, of each corner can be obtained with GPS and a renewal is sought very accurately. For new mining lease areas, stations around mining lease area required can be established as per surface features in relation to geological occurrence of the mineral, their values can be obtained through GPS, area calculated and mining lease is applied. Having done this survey with the help of GPS, the most modern tool, the lessee can win the confidence of Forest officials, State Govt. officials etc. involved in inspections and the process of granting of Mining Leases.
- Documentation of land holdings:
Coal industry needs land in huge extents. After the boundaries of the land holdings are jointly established by Forest/Revenue authorities and the mining company, the pillars can be surveyed with the help of GPS and the locations are documented. Subsequently, when the land use commences, the intervisibility of boundary pillars gets affected and the document can be used to reestablish the lost boundary pillars without any source of disputes.
- Establishing control stations around OCPs:
At OCPs, permanent stations can be built, whose values can be obtained through GPS and a good, accurate plan with control stations can be prepared. Periodically they can be checked for their positions. Experience reveals that the positional values remain unchanged over years.
- Training the present generation to face future challenges:
There can be no doubt that GPS becomes an essential tool over the forthcoming years. In case GPS is available with the mining company, proper training can be given to all those who will be required to use them in future. A physical touch of the instrument gives more knowledge than its view in a pamphlet.
Conclusion:
GPS can be very well used in mine surveying also initially for the purposes mentioned in the above paragraphs. An S & T project to assess its usage in Opencast projects for estimating the excavated volume can be organised jointly by vendors, Research Institutions and mining industry.
The views expressed in this paper are exclusively of the authors and need not necessarily belong to the organisation for which they belong.
The authors are thankful to the management of the Singareni Collieries Company Limited for having accorded their approval to present this paper at the 2nd Asian GPS Conference.
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