Thursday 12 May 2005
Still shovelling
No matter what you need to get done at Halley, from snow chemistry experiments to to clearing buried vehicles, it always seems to involve shovelling snow. This week was no exception, but with the added inconvience of being 25 metres below the surface.
I don't think I've talked about the melt tank here before so I suppose I should start at the beginning. It's too cold for rain at Halley so the only source of fresh water available to us is the ice shelf we're sitting on. To melt the snow we have a melt tank, which is basically just a big tank of water with heating elements inside. Each day, in any weather, 4 of us spend 15-30 minutes shovelling snow into the 50cm wide chute. The snow falls down the chute into the tank where it melts, giving us enough fresh water to supply all our needs for the day.
Why do we have to shovel snow by hand every day when we have bulldozers? That's a question that has been asked many times down here - usually at about 9:15 in the morning! When the current station was built in 1990 the melt tank was on the surface, but everything here is quickly buried by snow accumulation. Today the melt tank is nearly 25 metres below the ground (that's six stories down). The chute that connects the tank to the surface is extended each year but it's not wide enough to allow us to fill it by dozer.
With plans for a new station on the horizon, it looks certain that we'll struggle on with the current system for the next few years. Hopefully when they build the new station they'll come up with a less time consuming approach. Options include a similar system with a bigger tank that could be filled mechanically or something more fancy like the Rodriguez well they have at the South Pole.
If all the shovelling isn't bad enough, a common problem in the summer is for the chute to get blocked. With the station population increasing from 16 to nearly 80 the heaters struggle to melt the snow quickly enough for the demand. Sometimes an icy crust forms on the surface and if the digging team aren't careful they can end up back filling the chute and blocking it. The worst blockage I've seen was about 4 stories of snow, but I've heard that once it was filled right to the brim before anyone noticed!
To clear the chute when this happens there are hatches at each level which can be opened to give access. Given a big stick and enough time the chute can usually be cleared without too many problems. Unfortunately many of the hatches won't shut properly. Fine snow has a way of getting through even the smallest of gaps so after a year of digging there's often a big pile of snow at the bottom of the shaft.
Clearing that pile was a job for this week. Here's what it looked like before we started:
The snow that built up below the chute. The handle of a shovel is just visible in the centre of the pile.
In the end it took four people a couple of days to dig it all out.
Technical note: I've fixed the notification system recently, so if you'd like to receive an email each time I post to this site, sign up here.
Posted by simon at 5:55 PM | Feedback (1)