Safe passage into the Tweed River requires a clear navigational channel and ongoing control over the sand shoals that form periodically at the river entrance. River training works and dredging have been undertaken since the late 1800s in an attempt to improve navigability. These works culminated in the extension of the training walls at the river entrance during 1962–65. Although extension of the training walls improved navigation for a period, the entrance bar reformed and again created navigation difficulties. As a result of the construction of entrance training walls, natural coastal processes, including patterns of erosion and accretion were altered in the region. After extension of the training walls in the 1960s, accretion occurred to the south of the southern training wall, resulting in an accumulation of sand along Letitia Spit and subsequent significant erosion along the southern Gold Coast beaches. Eventually, the sand moved past the end of the breakwater and created a large, shallow bar at the Tweed River entrance that was hazardous to navigation.
Vertical Image from 1974 showing eroded beaches at north Kirra and significant shoaling at the Tweed River entrance
The Tweed River Entrance Sand Bypassing Project (now known as Tweed Sand Bypassing, TSB) was formulated following extensive negotiations between the New South Wales (NSW) and Queensland (Qld) State Governments to overcome these problems. Agreements between the two States were reached by signing of a Heads of Agreement in 1994, to carry out a joint project in order to achieve the two objectives of maintaining a safe navigable entrance to the Tweed River and restoring and maintaining the amenity of the beaches on the southern Gold Coast of Qld. Legislation was subsequently adopted in both NSW and Qld for the sand bypassing project.
Tweed Sand Bypassing was designed to be conducted in two stages. The first stage, which was completed in 1998, involved dredging more than three million cubic metres of sand from the Tweed Bar and entrance to create a navigable channel. This dredged sand was used to nourish the southern Gold Coast beaches, including Coolangatta and Kirra.
The second stage has involved construction and operation of the fixed sand bypass system as well as dredging from time-to-time, as required, to keep the Tweed River entrance navigable. A contract (Concession Agreement) was entered into between the NSW and Qld governments and TRESBCo (a subsidiary of McDonnell Dowell constructions) to build Tweed Sand Bypassing and operate the system until September 2024.
Vertical Image from 2020 showing nourished southern Gold Coast beaches and a navigable Tweed River entrance