Upper Parramatta Source Control

Customer: Sydney Water

Location: Parramatta Region, NSW

Delivered: June 2020

The Challenge

Time was of the essence during the Upper Parramatta Source Control project. Whilst schedule is always a crucial part of delivering cost-effective outcomes for our customers, Sydney Water had a mandate to deliver a completed program of works by 30 June 2020.

The crews encountered unforeseen issues at many of the varied locations which required changes to be made to the design. This led to variations to the project scope which required design, approval, and planning before works could commence. Wet weather, asbestos contamination, environmental concerns, and the rising threat of COVID-19 put further pressure on the already-tight schedule.

The Solution

Unforeseen challenges put pressure on the tight time constraints of this critical upgrade project. By challenging conventional processes and procedures, upskilling our people, and introducing flexible scheduling across 7 crews, Interflow was able to manage delays and uphold its commitment to Sydney Water.

Stakeholder management also played a crucial role in the success of this project. Through open communication with Sydney Water, Councils and other stakeholders, Interflow was able to identify many of the challenges early and manage design changes and variations in a way that minimised delays.

The Project

Sydney Water has a program of works designed to reduce the impact of wet weather overflows on the environment. Interflow was engaged through this program to deliver the Upper Parramatta Source Control project aimed at reducing the inflow of stormwater into the sewer network through existing Emergency Relief Structures (ERS). Sydney Water had a mandate to deliver these works within an extremely tight timeframe, and Interflow was ready to rise to the challenge.

The project was split into two packages and covered an impressive 47 site locations. The varied works involved the construction of new chambers, retrofitting one-way valves into existing assets, and building new headwalls to facilitate the installation of further new valves.

The challenge for the project team was planning and delivering works at each of these distinct sites, many of which came with their own unique design complications, community needs, and environmental concerns. By engaging stakeholders early, Interflow was able to plan around many of these challenges and incorporate re-designs into the initial project schedule.

Hardworking crews faced further challenges on this essential upgrade project. Despite early engagement and careful planning, unforeseen design changes, wet weather and the rising threat of COVID-19 all posed a threat to the schedule on this time-critical project. Interflow took an agile approach and introduced streamlined processes and flexible scheduling to deliver the works well before Sydney Water’s committed deadline.


Interflow developed a number of new work methods to complete this project on time and on budget and without any interruptions to service, or safety or environmental incidents. The solution has been engineered to take all loads, including soil, traffic and groundwater. This project has extended the known capabilities of spiral-wound lining and has pioneered methods that can be applied to other projects in the future.

Taking an agile approach to project management