Saturday 30 July 2011

Rocks, rocks and more rocks

As we reported a couple of days ago, there had been some problems with two collapsed cable ducts. This had prompted us to completely excavate the cable trench in that sector and replace the ducting.

Well, although we managed to get those rocks, the ducts were still moderately close to the surface. Thus the decision was made to continue digging down to better establish to trench and put the ducts at a safer depth.

Removing the last few 'pebbles' from the trench bed was non-trivial and it took a large portion of the day to get things to an acceptable state.

Of course, other LOFAR stations would not have had this problem (although the RAF-base foundations at Chilbolton may have come close). They tend to be on flat ground, perfectly drained, with a decent layer of top-soil, manicured lawns... okay, okay, I'm exaggerating now, but you get the idea.

Put a massive receive array in a rugged location and you can only expect rugged ground conditions too.

Anyway, here are some of the photographs that we took during a day of very hard work.

Rauno Oikarainen, Marko Kauranen and Pertti Nissinen pause
for breath before lifting out one of the smaller specimens.

Markku Postila and Rauno Oikarainen drive in some levers to try to dislodge the next one.

Some were a bit big and required some mechanical assistance for their removal.

Stuart Keenan and Marko Kauranen fit some lifting straps around an
even larger example. (Watch out for any lurking lemmings, Stuart!)

But even the Land Cruiser couldn't manage this one.

A borrowed tractor from the University of Helsinki was used to finish the job.

With all the rocks (finally!) cleared from the trench we put down a layer of sand to even things out and then recommenced the laying of the cable ducts ready to run the cables. There will be some more photographs of that coming soon. (Hopefully by the end of the weekend, the web log will have caught up with its own progress reports!)

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