Guest blog: How to move an Antarctic research station #2
6 March, 2017 Halley
This is Part 2 of a guest blog written by Ramboll engineer Ben Rowe, who was embedded with the British Antarctic Survey for 11 weeks to advise and assist with the challenging task of moving Halley VI 23 km upstream away from the path of a previously dormant ice chasm.
Friday December 30th – First Halley Module is moved.
It’s a sunny but very cold windy day. Six Adelie penguins walked through site at the southern end. We waited for the STMO (short term maintenance outages) power generator necessary for the hydraulics system and the vehicles to do preparation works to separate the H1 module.
We successfully unhooked the H1 module stairs so that we could lower it when necessary. I carried out a number of final checks on the various frames that are used for towing the first H2 module across to the new site tonight.
We again discussed the separation of the E modules and the complexities of support on a pair of cranes whilst pulling the E2 away. This is complicated by having to do so with the legs fully extended – with risks of damaging the mid-leg bearing. It was vital that we did this smoothly whilst monitoring movement at ski level and on the bridge.
The first Halley Module, H2 successfully arrived at the new site, known as VIA, just before 2am to be greeted by the Station Leaders, Project Manager and number of the new site staff. The chief engineer was delighted that the stopping distance was just as I had assessed a couple of weeks ago and this will give us confidence in stopping the other modules. We were all delighted to have safely and successfully moved this first module.
After some work to disconnect the load cell and snow depth sensors, those of us travelling back to site VI jumped into the sledge to make the return journey. Although the sun does not set below the horizon the night temperature drops and combined with the wind chill from the sledge speed we were feeling frozen and reluctantly wide awake. However after an 18 hour day and this chilly trip back we were pleased to go to warm beds satisfied after successfully moving the first module.
Saturday December 31st
Today we were getting the plastic membrane under the legs of the H1 module ready for the next move, scheduled for Sunday evening. We winched the module forward to get separation from the E2 module. This took around 26 tonnes (and a round a quarter of the module weight) to break the static friction (stiction) and get some movement.
In the evening we held the annual summer BBQ outside and to bring in the New Year.
Sunday January 1st 2017
Today I checked the H1 bolted connections on the towing frame and noted all was good apart from a poorly fitting rear steering tie. We came up with a solution to overcome this.
The final check ahead of this evening’s move was a check on the A-frame connection and load shackles. We leave to quite a crowd at site VI and arrive to a small group at VIA. Again another cold sledge ride back and a very late night.
Monday 2nd January
The routine of moving the modules is becoming slicker, and I’m managing my input to suit the night moves.
Wednesday 4th January
Today was a big day as we separated the E2 module with the bridge attached. During the preparation the fixed pins had been removed so that as E2 was pulled away the bridge would stay where it is, and could be slid out of the E1 letterbox and lowered onto the temporary support frames.
To enable this tricky part of the operation, we had the normal Piston Bully and two dozers at the front of the E2 module, and a dozer behind pre-loading the rear skis to help gently move it away. We also had the bridge suspended from two cranes and all the bridge connections free.
As the E2 module was gently moved away the bridge moved with it for approximately half a metre so a stop was called. The cranes lifted the bearing a little higher and this allowed the E2 unit to be pulled clear. The bridge was then lifted down onto the temporary support frames and the vehicle team added some strops to reduce the stress on the frame whist transporting it to VIA. After some adjustments we got the bolts into various towing frame components for module E2, I then checked all was good for the night’s move. This time, a couple of people from the MEP team over-nighted with the module which was great as I got a full night’s sleep.
Friday 6th January
Today will be my first day’s work at site VIA.
I was told that the H2 module was within one degree accuracy from the setting out established in summer 2016, and that we should use it as the basis for the other module alignment. I was asked to set up a line to advise how much the H1, E2 units need to be moved laterally. Given the combined length of the modules was approximately 200m this 1 degree of variation would equate to a 3-4 metre offset from the current flag line. So it was important to reset the flag line so that we could minimise the amount that future modules arriving on site would have to be moved into alignment.
This took me back to my early engineering days. The only instrument on site at this time was a dumpy level, which is fine for levelling, but pretty useless for any bearings etc. So first thing we got some timber pegs cut and hammered these into the snow so that I could form a stable base for the tripod legs that was not going to settle into the snow during the days use.
I used the dumpy level as a simple sight line across the three modules. I was able to record offset readings on the H2 module legs and therefore establish a leg line relative to my sightline. Using horizontal lengths between the module legs I was able to determine the offset to the other module legs to extend the H2 alignment.
In the afternoon we were visited by a six Adelie penguins, quite remarkable given that we must be 30-40km from the coast.
Monday 9th January
Today having aligned module E2 we pulled it onto H1, and re-connected the Trelleborg.
Tonight I spoke to my youngest son, Daniel, as tomorrow he leaves to go traveling, starting in Thailand then onto Cambodia, Vietnam, Laos, Malaysia and then maybe New Zealand and Australia. It’s not something I ever thought about at 18, as it was always about further qualifications to start a career. However I am proud that he has the confidence and independence to do his own thing. So I sent my love and asked him to stay in touch so we know he is ok. This might seem obvious, however most lads do not see the need to communicate at all unless they need something or it’s gone horribly wrong! In between these times it would be nice to know where he is in the world and what he’s exploring! I followed up our chat with some photos from down South. He said that he had set up the digital photo frame that I gave my wife Luci at Christmas, to pick up photos uploaded to the web from wherever he is during his travels. This sounds easier for him and more likely than a call!