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Green Square Sewer Diversion & Manholes

Green Square Sewer Diversion & Manholes

Client: Mirvac

Asset Owner: Sydney Water

Project description

This Scope of Works relates to construction works at Mirvac’s Green Square Site 15 Project. The project consisted of four (4) mid-rise apartment buildings (up to 23 levels in height) with a total of 342 quality apartments.

The Site is located in Portman St, Zetland NSW 2017.

As the project including a three (3) story basement carpark, Mirvac were required to carry out a sewer diversion of the line that was crossing the site.

Killard Infrastructure were involved in the following works:

  • Caisson Shaft excavation as boring launch pit
  • Underboring works of two 45-metre lines
  • 3 x 1800mm internal diam. manhole constructed up to 9 metres deep
  • Connection works to the existing sewer infrastructure and disuse of redundant sewer line

Killard subcontracted and managed the boring works that included an OD700mm steel pipe being case bored to allow the installation of DN450 GRP sewer carrier pipes.

Due to the manholes being located beneath high voltage power cables, a DN5500 segmental steel shaft was installed using an excavator with a telescopic arm to reduce the risk of overhead electrocution as sheet piling and shoring boxes were ruled out. Two receive pit excavations were dug on top of the existing sewer line to allow the construction of the manholes to connect the existing sewer to the new alignment. The manholes were constructed in each shaft and lined with a HDPE protective liner.

Plant type

35t excavator, 33t excavator with telescopic arm, AKS liner, dumper, skip truck, shoring boxes, caisson shaft segments

Pipe Size & Length

Pipes: DN700 Encasement Pipe & DN450 GRP pipe x 90m

Manholes: – 3 x 1800mm ID x 7m to 9m deep

Design and build dates

Sep 19- Jan 20

Project value

Killard Scope $1.25m

Roles and responsibilities

Killard – Sewer and Manhole construction

Stakeholder liaison

By Project Management Personnel

Safety and environment

Safety incidents – nil

Environmental incidents – nil

Client referees

Mr. Norm Chow & Mr Matt Stephenson



This project demonstrates our expertise and ability to use technology and innovation to adapt to obstacles arising during a construction program.
With one manhole being constructed in the middle of the Portman St, extensive community consultation was carried out to minimise disruption to the public. This also included detailed traffic management and control.

Killard Infrastructure has been an approved Sydney Water contractor for Works for more than 20 years.

Project Info