Ah ok. Yes, that's what I thought too, but our civil engineer wants to do the pipelines only after the houses are standing. He says it doesn't make sense to do it before...
if he removes 30-40cm of topsoil for the construction road, he already has half the depth of the trench, and 1.5m from the fence the trench is never ever a lane. Ask him for 2 quotes, now and later