High, persistent moisture content in the soil can conduct the frost deeper since it doesn't act as an insulator when it's wet (much like any insulation). Compression (like walking or driving) also can accelerate driving the frost deeper too. We have to be remarkably competent about laying water lines up here, as long as the cold season can be, and the way it's not just plain cold, but goes through repeated freeze-thaw cycles that assure moisture is driven down far.
My water line is 8-10' deep and I made sure to keep it in a shaded area that doesn't get driven over. It only freezes where it comes up into the cabin. Which it does every few weeks during winter. It's no fun when that happens, but this last stretch of bitter cold and wind managed to freeze it badly enough that it took me a day or so to thaw it. I think the heat tape came unplugged too.
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branchandroot
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Date: 2007-02-04 05:47 pm (UTC)My water line is 8-10' deep and I made sure to keep it in a shaded area that doesn't get driven over. It only freezes where it comes up into the cabin. Which it does every few weeks during winter. It's no fun when that happens, but this last stretch of bitter cold and wind managed to freeze it badly enough that it took me a day or so to thaw it. I think the heat tape came unplugged too.