The project was undertaken to reduce the number of wet weather overflows from 10 locations in the area around Park Avenue and Glover Street in Mosman. The work comprised of upgrades to some of the overflows, amplification of some sewers and sewer diversions to areas of the system with spare capacity. The individual solutions were combined to minimise disruption to the local community. Primarily targeted at swimming sites, the program will provide benefits to the environment and human health, and is part of Sydney Water’s long-term SewerFix program of sewerage system improvements.
Due to the complexity of the bore UEA engaged the services of a steering engineer and a Paratrak 2 system. UEA utilised its 45 tonne Vermeer D100 x 120 HDD rig to undertake the pilot bore which was completed in twelve days and within 30mm of the required intersection point.
Site specific challenges included maintaining the grade, working in a densely populated area of Sydney, intersecting an existing manhole and limited room for the new polyethylene pipe sting.
The design of the project allowed UEA to utilise PDC forward reamers with all cuttings and drill mud returning to the drill face. UEA chose to upsize the hole in two passes – an initial cut of 13 inches and then a final cut of 18 inches. Upon completion of the ream UEA pushed the pipe into place.
For more information about this project or UEA Trenchless, please send enquiries to Steven Hopkins.