Merimbula Sewage Treatment Plant Upgrade and Deep Ocean Outfall

We are continuing environmental investigations around Merimbula Bay to help our project team develop options for the deep ocean outfall and Sewage Treatment Plant upgrade. This will make our iconic beaches and lakes cleaner and improve public health.

In October, we completed heritage investigations at the Sewage Treatment Plant to search the area for heritage items, including items of Aboriginal significance. In November, we carried out geotechnical investigations around the exfiltration ponds at the Sewage Treatment Plant. The results will be correlated with available historical information to help us understand ground conditions to inform infrastructure design.

In May, we carried out our second dye dispersion test. These tests help us to understand how waterborne materials travel and spread in the bay’s currents.  This important information will feed into a model we will use to develop options for the deep ocean outfall.

Working with the Community

Our Community Working Group has been meeting regularly since the beginning of the year. They are working collaboratively to select the location of the deep ocean outfall. We will be meeting before the end of the year to give them an update on what our investigations have found.

We’ll be back out in the community in early 2019 to provide you with a project update. We look forward to seeing you then!

We are continuing our work on this long-term investment that will improve the water quality of our iconic coastal environment, from the beaches to the lakes.  

In November 2017, we introduced the project to the community to explain the project process and better understand your concerns. We did this through drop-in community information sessions and briefing sessions for key stakeholders. Thanks to everyone who gave us valuable feedback. We will use this to help develop the concept design.

Our community working group (CWG) is using your feedback to help select the location of the ocean outfall. The CWG first met in December and they will be visiting the STP site this month to better understand the plant’s current condition. They’ll meet again in March to continue assessing the possible location of the ocean outfall.

This month we’re doing our second dye dispersion test in the bay. We did our first test in August 2017. By testing at different times of year, we can get information on how currents behave in different water temperatures. To do this, we release a harmless, bright red fluorescent dye into the water at several locations. This shows our designers how waterborne materials travel and spread in the bay’s currents.

This March, we’ll have another round of drop-in community information sessions and briefing sessions for key stakeholders. At these sessions we’ll be able to give you more detail on the investigations we’ve done and the progress of the CWG.

We look forward to seeing you then!

We’re continuing fieldwork to gather more information about Merimbula Bay. This will help our project team develop location options for the deep ocean outfall and STP upgrade.  

Starting this week, we are doing hydrographic surveys. This means scientists in boats will be measuring the physical parts of the bay like water depth, surface of the seabed and the shoreline. 

Throughout October and November, we surveyed the marine ecology in the bay to better understand habitats and refine existing maps of the area. We used underwater videos at selected locations to identify habitats and groups of fish. Abalone fishing is vital to the economy of the area. We included specific surveys to assess the abundance of abalone in shallow sub tidal reef areas.

In early September, we did flora and fauna surveys to list the different plants and animals in the area between the STP and Merimbula Bay. This information will help us understand the area’s variety of plant and animal life, and minimise impact from the project.

We carried out dye dispersion tests in Merimbula Bay earlier this year in August. We released a harmless, bright red fluorescent dye into the water at several locations in the bay, including Haycock Point (east and north). This information will show how waterborne materials travel and spread in the bay. It will help our designers understand how water flows there. We will do this testing again in the warmer weather.

Bega Valley Shire Council will carry out dye dispersion tests in Merimbula Bay in August, weather permitting.

With Council commencing an environmental assessment process and developing a concept design for the Merimbula Sewerage Treatment Plant (STP) Upgrade and Deep Water Ocean Outfall, the testing is critical to the hydrodynamic modelling for the project.

Council’s Water and Sewerage Services Manager, Jim Collins, said Council is acting on advice from the NSW Environment Protection Authority and also local community concerns, that the existing beach-face outfall at Merimbula STP is not sustainable.

“The information we receive from these tests will show the dispersion rates and travel times of waterborne materials in the bay, and will help our designers determine the best location for the placement of the deep water ocean outfall,” Mr Collins said.

“The process will involve Council’s consultant hydrologists releasing a harmless, bright red fluorescent dye called Rhodamine into the water at up to four locations in the Bay, including Haycock Point (east and north) and Merimbula Embayment.  

“The exact timing of the testing is dependent on weather and ocean conditions; however Merimbula Bay will be open and safe for all water users during the tests.

“Rhodamine, which will disperse rapidly, follows the pathways of currents closely and has a low impact on water quality. It will be used to measure how long it takes the currents to move water between predetermined sampling sites, with the testing set to take a few hours in each location,” Mr Collins said.

Photograph:  Merimbula Bay looking south towards Pambula Beach and Haycock Point with the Pambula Merimbula Golf Course and Merimbula Sewage Treatment Plant in the foreground.

Bega Valley Shire Council is taking action on advice from the NSW Environment Protection Authority (EPA) and the community that the existing beach-face outfall at Merimbula Sewage Treatment Plant (STP) is not sustainable. 

Council’s Manager of Water and Sewerage Services, Jim Collins said the Merimbula STP needs upgrading to meet environmental regulatory requirements. 

“In recent years, the existing beach-face outfall has caused community concern around the aquatic environment and public health. To address this issue we have appointed engineering consultants AECOM to help with the upgrade” he said. 

The next step for the STP upgrade is developing a concept design and environmental assessment. This will include environmental investigations, design, community consultation and preparing an Environmental Impact Statement (EIS). 

“This is a complex process which will take between 18 to 30 months and Council aims to finish the process by 2019.

“Community involvement and consultation will be a key part of the project. In the coming weeks, the project team will launch a website to provide information on the project and how the community will be able to provide feedback.

“We encourage the community to provide feedback and attend drop-in community information sessions when they are announced,” Mr Collins said.