Advanced Backflow and Flood Protection for Critical Infrastructure Along the Hawkesbury River

AWMA is proud to have played a key role in the successful delivery of the Cornwallis Road Culvert Upgrade, a critical piece of infrastructure that restored access, improved flood resilience, and protected the surrounding road and riverbank environment along Cornwallis Road beside the Hawkesbury River in NSW.

Following significant damage during the 2022 flood event, where large sections of the riverbank and road were washed away around the existing culverts and headwall, comprehensive remediation works were required to reinstate and strengthen the site. The project focused on replacing damaged structures, improving foundation conditions, and installing high‑performance flap gates engineered to withstand extreme hydraulic loading and provide long‑term reliability.

Construction progressed through challenging site conditions, including four separate flood events that tested both the works program and onsite operations. Despite these impacts, the project team achieved key milestones while ensuring safety, quality, and long‑term performance were never compromised.

As part of the remediation works, AWMA supplied and supported the installation of two 2400mm (W) × 2400mm (H) Grade 2507 Stainless Steel Flap Gates, installed within the Cornwallis Road culvert headwall at the Hawkesbury River. Designed to withstand up to 11.5 metres of head pressure, these high‑performance flap gates provide robust backflow prevention during flood events while allowing efficient discharge under normal conditions, significantly enhancing the resilience of the road and surrounding infrastructure.

The completed works restore connectivity along Cornwallis Road, improve flood resilience and bank protection, strengthen long‑term infrastructure performance, and protect the surrounding Hawkesbury River environment.