GFWAust were appointed to backfill the annulus along the 550m bore around the mains sewer pipe.
As part of the sewer fix program, Sydney Water constructed a new mains sewer from Glover Street to Park Avenue in Mosman. The 355mm diameter pipe was installed in a 450mm diameter bore excavated by UEA. About 80m from the top of the 550m bore groundwater was intersected at a rate of up to 20,000 litres per day. From a manhole in Park Avenue a plug was formed with non shrink grout prior to injecting over 24m3 of flyash grout into the top of the bore from Glover Street. The top of the bore was then also plugged with a non shrink grout. The works were carried out in a busy urban street with great care required to limit the impact on the local community.