Trenching in Granite without explosives

My friends at Montdami Construction were laying the underground services as part of a new housing estate project when some hard granite was encountered, they had a shot at hammering it with a big hydraulic breaker on a 36 Tonne machine but the progress was not substantial and the breaker point was worn down quickly. Normally we would just blast the rock with high explosives and the show goes on, no big deal. Not this time... Parallel to the trench we were working in, is another underground service - a very