Ethylene glycol

[Guest gusgus]

A strange occurence happened at my dads work and we can't figure it out. Hurricane Ivan completely flooded the basement (about 10 feet of water). They have a 50/50 mix of ethylene glycol and water in a 200 gallon tank which was set at 35 degrees F and was used for circulating through condensors. It had a 1 1/2" closed cell insulation lid which had lifted as the water rose, exposing it to the muddy water pouring in the building. 2 days later when the basement drained, he and his workers were amazed to find that the exposed tank was exactly in tact, not a speck of muddy water in it. It stayed just the way it was before the flooding. Can anyone explain this?