The Limestone conditions in Spearwood proved to be of little concern for the Rockman Microtunneler.  Rockmans specialised rock drilling system was utilised to install a 400 diameter steel sleeve as a carrier pipe for DN150 sewer pipe.  As the sewer was a gravity line, it had to be installed to exacting position in order to piece up to an existing line laid down stream at a grade of 1/240.

The drive was just 50m long, but due to the vicinity of some major underground services crossing the path of the sewer line, a trenchless solution was proposed.  The services crossing the sewer included a large Asbestos water main, high pressure gas main and fiber optic cables.

Because of the danger associated in damaging any of these services it was considered far less risky to carry out this part of the works by Microtunnelling. The drilling was completed in less than three days, with a final bore deviation from design of less than 5mm.