Above: The mine tunnels are bored through almost pure salt. Salt dust coats all the equipment and most of the workers. Fortunately, salt is non-toxic and non-flamable, unlike coal, so the dust is not a safety problem. At this depth in the Earth the temperature is almost a constant 95° F year round. Salt has an affinity for water and the mine air can be quite dry even though safety requires constant ventilation. As a result, workers in the mine loose fluid both through perspiration and simply by breathing. The team installing the seismometer hardware needed to carry plenty of water since the installation would take all of the day.

Below: Preparing to poor the cement slab that will form the instrument pier. The slab needs to be as level as possible.