The location

The University Hill Precinct Development in Bundoora is a light commercial and housing estate on 400 acres. Originally the site of the State Government Jane Field Hospital, it is located in an environmentally sensitive area.

The project

The project was undertaken for Yarra Valley Water and principal contractors MFJ Constructions. This involved the installation of 900 m of 355 mm diameter poly pipe for a branch sewer for the housing and commercial development. The design was undertaken by MWH Global, which was divided into three different drilling set ups of 450 m, 320 m and 161 m respectively.

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Line 1

This was drilled in one length from the downstream end. The line went through a hill and at its deepest point was 20 m deep. The drill rig was then transported to the top end where the pipe was then pulled in. Manhole No 1 was installed over the top of the pipe after the pipe installation was completed, with the pipe being at the correct invert level.

Line 2

This was also drilled from the downstream end and was drilled and finished at manhole No 2, at this point being 14 m deep. The ground conditions of river cobble and mud stone were going to make the installation tricky due to the possible collapse of the hole. The 320 m pipe was installed by using thrusting technique.

Line 3

This was drilled from the upstream end back to manhole No 2, at which there was a tangent point where the line had a change in direction. The pipe was installed by using a thrusting technique. This Line was always going to be critical as this had to be accurately joined with the downstream line at manhole No 2 with a 30 mm tolerance. The set up area was a highly sensitive Aboriginal heritage site which required permission from an Aboriginal Tribal Leader. Although this did cause a slight delay the people were very good to deal with.

The technology

The technology utilised by AHD Trenchless gives more control and accuracy in the application for achieving on-grade drilling through all types of ground conditions.