oh yes it is... just gotta spend more time and make a visqueen tent.
our soil is frozen about 3-4' deep here. boss had a trailer show up on the construction site with a diesel furnace inside, recirculating pump, several hundred feet of hose & reflective heat blankets. yesterday the soil was thawed deep enough inside the garage of the house and the exterior porch that the soil was workable & concrete was poured. the diesel salamander heaters are still running under the drapery of visqueen but its entirely manageable
frost laws are gonna come into effect soon around here and the trucks won't be capable of driving heavy loads on the roads for a few months though.