West Hornsby & Hornsby Heights

“Delivering Biological Nutrient Removal Upgrades”

What’s the best way to ensure successful upgrades to two Australian sewage treatment plants at the same time?

That was the task of the joint venture team of Transfield Construction/MWH (TMW) for Sydney Water Corporation (SWC) -– Australia’s primary water and wastewater provider for New South Wales.

The team’s delivery of Biological Nutrient Removal (BNR) upgrades to two sewage treatment plants – West Hornsby (42-ML/d) and Hornsby Heights (21-ML/d) – received industry recognition.

The design-build project was honored with the "2002 New South Wales Project Management Award" in the construction and building category. The Australian Institute of Project Management established the awards program to recognize and honor outstanding achievements in project management.

Challenging Circumstances

The West Hornsby and Hornsby Heights Sewage Treatment Plants serve a combined population of approximately 90,000. TMW designed the upgrades to both plants simultaneously, and dealt successfully with differences in process arrangement and capacity.

The team worked within tight confines of limited space, but kept the plants operational at all times. At the peak of the design process, more than 20 engineers and draftsmen handled civil, structural, mechanical, process, electrical, control and instrumentation factors.

The overall effort included the coordination of more than 150 live cut-ins with plant operators.

As SWC Managing Director Alex Walker explained, “The project team was able to meet challenging construction work, while minimizing impacts on the local community and environment. At the same time, they maintained the smooth operations of both treatment plants.”

The A$22 million upgrades to the sewage treatment plants were delivered on time and under budget. Since going into operation in May 2002, the plants have eliminated sewage-induced algal blooms in the Berowra Creek. This has significantly improved the effluent quality.