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I am working with old borehole coordinates in the Mpumalanga region in South Africa. I suspect the coordinates are referenced to Cape Datum (Clarke 1880) before the Hartebeesthoek 94 datum was introduced. When I try to convert them using QGIS or EPSG the answer that I get is inf;inf. My input coordinates are X+29383357;Y-745884.

Can you help me?

Here is an image.

enter image description here

The reason why you had to divide by 10, I don't know, but it certainly delivers a better answer. The reason why you had to switch X and Y, makes me think that it could be a coordinate system similar to Hartebeesthoek Lo29 (ESRI 102487) and Hartebeesthoek Lo29 (E-W) (ESRI 102567) but I am not sure. What I have figured out by trial and error, is that if I add the number 66000 to your X coordinate, the borehole plots on the farm Langverwacht 282 . This farm name is also mentioned on the borehole report sheet that I have uploaded. So intuitively I think we are moving in the right direction, but I am not sure why.

Map of LangverwactHartebeesthoek Lo29

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  • Suspect you'll need numbers not strings to do a conversion, so will need to work out what X and Y are first. Also not sure what you mean by convert them using EPSG, do you mean some conversion tool supplied by EPSG (epsg.org)?
    – nmtoken
    Commented Mar 15 at 17:33
  • It would be nice to see what you see. Please post a pic of the sheet you got these numbers from.
    – Pointdump
    Commented Mar 15 at 17:53
  • Thank you. The transformation tool by EPSG that I have used can be found here: <Transform coordinates - GPS online converter (epsg.io)> There is also a spreadsheet published by National Geospatial Information that can be used for the transformation which can be found here: <NGI Coordinate Conversion Utility (dalrrd.gov.za)>. That also gives me nonsensical answers, or I am not using it correctly. I am struggling to upload an image or a file in the comment section. If somebody can guide me through that, I will happily oblige. Commented Mar 16 at 7:11
  • Edit your original post to add an image.
    – Pointdump
    Commented Mar 16 at 7:23

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The coordinates seem a bit large, so divide both X and Y by 10, and switch X and Y to work in EPSG:22289 Cape/Lo29:

Y: 2938335.7, X: -74588.4

Puts your borehole about 20 miles NorthEast of Standerton, Mpumalanga.

enter image description here

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  • Thank you. The reason why you had to divide by 10, I dont know. Commented Mar 19 at 7:26

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