Saturday 7th January – surveying for accurate alignment


Today I used the dumpy level for its intended function role and levelled H2 and H1 soffits so the Trelleborg could be re-connected. I also set up a new surveying position that would allow me to sight through H2 and extending the sight line for the all the future module positions. I marked this with a new flag line and the offset at the end of the modules that I raised yesterday so this was then clear for everyone.

We also set up the lattice towers that form the Southern Gateway burying the foundations some three metres below ground level.  This will allow the connection of the modules with external infrastructure as well as being the datum point for future level surveys.
At the end of the day the BAS Project Manager, Station Leaders and I discussed the new alignment.  I suggested we could go back to the original setting out points and simply re-create the original bearing and compare with this new line. The setting out is only relevant to lengths of infrastructure connections and most importantly the snow wind tails which impact on the snow management around the building. The accuracy of the original snow tail measurements on this empty site in 2016 is unknown and further complicated as the Brunt Ice Shelf rotates by around 0.4 degrees each year so the accuracy will change with time.