Esperance Bay Coastal Erosion
Coastal erosion along Castletown Quays occurs annually due to sand drift from west to east. The Shire needs to undertake Sand Renourishment to maintain the buffer between the ocean and infrastructure.
Erosion of the Esperance Bay has always been a problem but has been exacerbated as a consequence of development that has been undertaken in the bay. This has changed the natural flow of sand drift. Currently there is an average annual net deficiency of 20,000m3 of sand in the bay. This is currently solved by placing approximately 20,000m3 of sand each year in the erosion zone know as Sand Renourishment.
The Shire receives an annual grant from the Department of Transport to cover up to 50% of the cost of these works each year.
What is the Shire doing?
In 2018 the Shire engaged BMT to undertake a Report to look at the Esperance Bay Coastal Erosions Options and recommend a long term solution, found here. The report looked at 5 options with some different variations.
- Sand Renourishment - Status quo
- Sand back-passing – Take sand off the Castletown beach and pump it back to the erosion zone.
- Coordinated dredging and Sand back-passing – coordinate with the Bandy Creek Boat Harbour dredging program to pump the dredged sand to the erosion zone
- Seawall – Offers direct protection of the coastline from erosion
- Rock seawall
- Sandbags seawall
- Groyne(s) – Changes the shape of the bay to alter the equilibrium point
- 1 large rock groyne
- 2 T rock groynes
- 3 T rock groynes
- 4 small rock groynes
- 4 small sandbag groynes
From the report the most cost effective solution over 20, 50 and 100 years was the Coordinated Bandy Creek Boat Harbour dredging & sand back-passing that offered a number of benefits. Otherwise we should look at constructing a seawall or groyne(s). Council resolved to investigate the possibility of a Coordinated Bandy Creek Boat Harbour dredging & sand back-passing.
The Shire engaged BMT to develop the Coordinated Bandy Creek Boat Harbour dredging & sand back-passing, including designs, environmental planning and liaison with the Department of Transport. The Trial for the dredged sand will begin pumping from early May 2021, between Monday and Saturday from 7:00am to 6:00pm, with the Trial expected to run until early August 2021.
Media Release - Sand Backpassing Trial Begins