We have a basement conversion in our Edwardian terrace, done 2 years ago, which is drained by a sump pump from the usual sump pit. The water table must be quite high because during the winter the pump hammers away at up to once a minute, the sump pit fills so fast. We've worked out we're draining next door either way as well as us!
We're wishing we'd found out about installing a gravity drain from the sump pit right at the start but the building programme did not bring the question up and we didn't think of it at the time. We now want to impact mole a pipe to connect the sump pit straight down to a deep inspection chamber of the surface water drain which runs down an alley through from the back between us and next door.
We reckon we can do this by moling from the drain inspection chamber up to the sump pit under the basement and then break through with the pipe below the level at which the sump pump kicks in to create a gravity drain outlet.
Anyone heard of this technique being used in this way?