Ovoid Sewer Project

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1914 Ovoid Sewer Project

Barwon Sewer Restoration (BSR) was awarded a relining contract that included upsizing three existing manholes and constructing four new ones on the Geelong 1914 Ovoid Sewer Main. The project aimed to create corrosion-resistant manholes capable of accommodating the new liner’s size.

Scope of Work:

Manhole Construction and Upsizing:
- Depth Variability: Manholes ranged from 2.5 meters to 7 meters deep, presenting diverse construction challenges.
- Rock Breaking and Structural Support: Required for managing an undermined 600mm GRP rising main.
Safety and Environmental Measures:
- Ventilation and Breathing Apparatus: Ensured safe working conditions in toxic atmospheres.
- Dry and Wet Abrasive Blasting: Utilized for surface preparation.
- Wire-Saw Cutting and Coating: Employed epoxy and polyurea coatings to enhance corrosion resistance.
Additional Challenges:
- Rock Breaking: In certain sections, the sewer main had been tunnelled through basalt rock, necessitating careful rock breaking. This was executed carefully to remove the rock without damaging the adjacent 100-year-old corroded structure.
- Structural Support: Required for managing an undermined 600mm GRP rising main.
- Preventing Water and Root Ingress: Implemented measures to protect the integrity of the manholes.
- Removal of 100-Year-Old Corroded Structures: Managed the safe dismantling and removal of old concrete.
Construction Approach:
- In-Situ Footings and Custom Pre-Cast Components: Combined to build the manholes, ensuring a robust and efficient installation.
- Polyurea-Coated Components: Used to achieve long-lasting, corrosion-resistant manholes.
Project Management:
- Minimizing Impact: Completed the project promptly to reduce disruptions to residents, traffic, and other contractors.
- Maintaining Sewer Flow: Ensured uninterrupted operation of the sewer main during construction.

Outcome: BSR successfully upsized and constructed the manholes on the Geelong 1914 Ovoid Sewer Main, overcoming significant challenges. The use of innovative construction techniques and materials resulted in durable, corrosion-resistant manholes, with minimal impact on the surrounding community and environment.