Background

The country town of Gundagai has security in sewerage infrastructure with a state-of-the-art treatment plant, pump stations and rising mains, all constructed above the 1:100 year flood level.

The plant uses the intermittently decanted extended aeration (IDEA) treatment process, in which micro-organisms in the sewage to break down organic matter. The effluent is then disinfected by ultraviolet treatment and chlorination, making it suitable for reuse. This has added social benefits, as it helps to drought-proof the nearby Bidgee Golf Course.

Cootamundra-Gundagai Regional Council engaged NSWPW to deliver the sewerage augmentation from inception to completion. Our services covered options assessment, concept and detailed designs including site investigations, geotechnical assessment, site survey and environmental assessment.

At the completion of design, NSWPW provided tender procurement services to secure an experienced contractor for construction. We also managed the construction works providing contract administration services and site supervision through the challenges of the COVID-19 pandemic.

Expert technical design support was provided throughout the construction phase, undertaking final site testing and commissioning to ensure operational compliance meeting design objectives.

Outcomes

Gundagai Sewage Treatment Plant augmentation was completed in July 2022, with the successful commissioning of the new treatment plant. The project was completed within time and budget.

The augmentation work included:

• new inlet work with screening and grit arrester
• new IDEA reactor
• concrete balance tank
• two sludge tanks
• sludge pump and dewatering system
• chemical storage and dosing
• UV disinfection
• effluent storage tank for reuse
• new pump stations
• rising mains
• new amenities building
• power upgrade and electrical services.

The sewerage augmentation will safeguard the community over the next 30 years and beyond.