Overview

The northern suburbs ocean outfall sewer (NSOOS) collects sewage from the northern side of the Parramatta river and transports it under gravity flow to the ocean outfall at North Head. Between Dundas and North Head the sewer has been in continuous operation between 90 and 105 years. In the last 30 years the sewer has experienced considerable deterioration of the internal concrete surfaces from the aggressive sewer environment leading to an extensive rehabilitation program. 

This presentation considers two aspects of the rehabilitation work related to the engineering heritage of the NSOOS. The first relates to heritage considerations that taken into account on the rehabilitation of high visibility above ground structures such as aqueducts and syphon structures. 

The second deals with the impact of the original decision to use of a very unusual concrete mix for the construction of the tunnel lining. The mix contains sandstone as aggregate which makes the concrete low strength and more porous than typical concrete and how this has played a major part in how the concrete has deteriorated and the impacts on methods chosen for rehabilitation.

Learning outcomes 

In this presentation you will learn: 

• An understanding how increasing modern demands on an old trunk sewer asset can have an impact on its performance in terms of the rate of deterioration. 
• A description of aspects that need to be considered and incorporated in the repairs for the rehabilitation of a highly visible aged sewer asset. 
• What happens when a highly unusual sandstone aggregate concrete is used for a sewer lining and how and why this has affected its deterioration performance. 
• A description of what processes were adopted for the inspection, assessment and repair of a sandstone based concrete tunnel lining.

Event program

In-person:

• 5.30 pm AEST – Registration opens and networking 
• 6.00 pm AEST – Presentation commences with Q&A session 
• 7.00 pm AEST – Presentation concludes

Online

• 6.00 pm AEST – Presentation commences with Q&A session 
• 7.00 pm AEST – Presentation concludes

About the speaker

Lance Horlyck MIEAust CPEng NER

Principal, SASTTI Joint Venture

Biography

Lance Horlyck is the Principal Engineer at SASTTI Joint Venture. For more than 30 years Lance has been working on the assessment and rehabilitation of Sydney Water’s structures including reservoirs, pumping stations, sewers, treatment plants, ventshafts, pipelines and buildings. 

This work has included the majority of Sydney Water’s heritage listed structures including such items as Crown St Reservoir – the oldest reservoir still in operation in NSW, the magnificent Centennial Park Reservoir, Johnstones Creek sewer aqueduct – the oldest reinforced concrete structure in NSW, Potts Hill Reservoirs, West Ryde Bolierhouse and Pumping Station, and most of the early water, sewer and stormwater systems constructed in the late 1800 and early 1900s. 

Lance has always had a strong appreciation for the heritage significance of the structures that he has had to assess and has consistently adapted and modified repair and renovation methods to preserve and minimise impacts on their heritage significance.