Deep Ocean Outfall

Community Work Group (CWG) – just a PR exercise?

BVSC claimed the Ocean Outfall is supported by the Community Working Group. This is what they had to say about their role in the process.

“To say the least we were quite taken aback with the limited two lesser treatment option scenario….we questioned what was the benefit of us being there at all? It left us feeling like we were just being used as a PR exercise, all very token stuff. “

” We were clearly informed by council’s consultants AECOM that as part of the EIS process it was a mandatory requirement to review all options and alternatives previously considered, plus to consider any new options and alternatives not previously assessed… With that in mind 8 out of 10 CWG members did prepare a draft proposal which was reluctantly accepted by the consultants to be forwarded to Council. Disappointingly we never did receive a response to that initial submission at all.”


Effluent is liquid waste from sewerage treatment, that has been aerated and chlorinated. Effluent from the Merimbula Sewage Treatment Plant is currently discharged onto Merimbula Beach. The Council is proposing to discharge the effluent into Merimbula Bay via a $30M pipeline extending 2.5kms at a depth of 30m. This places the pipeline less than 1000m from the artificial reef. No studies to date have been undertaken to assess any impacts upon the reef.

SWAMP is advocating for higher almost potable treatment and up to 100% reuse while any possible discharge can be from the current beach-face outfall.

Frequently asked questions; SWAMP answers

Is it true when BVSC says the combination of an upgraded STP, the ocean outfall and increase reuse “is the only solution” for this location (Merimbula) and the environment?
Answer: NOT TRUE.

East Gippsland, for example, boasts 100 % reuse across its eleven wastewater treatment plants. They have similar landscape challenges like Merimbula for water recycling. Zero ocean outfall as the ocean protection generates income to East Gippsland. They are the home of one of Australia’s largest fishing fleets and significant abalone industry. BVSC didn’t have any new reuse scheme disclosed in their plan. The combination of Byron Bay wetland, Shoalhaven REMS and East Gippsland water storage & agriculture irrigation scheme is a workable and practical solution for Merimbula.

What other reuse/recycling options are presented?
Answer: There are options to re-use the recycled effluent to irrigate agriculture. Potential recipients of recycled effluent include:

  • Pambula Merimbula Golf Course
  • Oaklands Agricultural Irrigation
  • South Pambula Agricultural
  • Lochiel Agricultural
  • Millingandi Agricultural
  • Wolumla Agricultural
  • Yellow Pinch Dam Indirect Potable Reuse

There are a variety of pipeline routes to service these recipients

What are the key challenges & constraints of other alternatives?
BVSC say:

  • The high capital
  • The operational cost
  • The topography (slope)
  • The construction footprint

SWAMP says:

  • The operational cost is mostly electricity, but the council didn’t consider solar power
  • Capital required for re-use and other alternatives is far below ocean outfall’s
  • Slope is a moderate challenge; many other similar projects (long pipeline) in NSW have been implemented.
  • The construction footprint could leverage powerline clearance and avoid residential and A1 highway.
  • The key challenges & constraints are BVSC’s mindset and attitude or other untold stories. There are proven successful examples can be implemented in Merimbula.

Did the council involve the community in the decision-making process?
Answer: YES but formed in the PR exercise mode. The community representatives refused to back council’s ocean outfall decision while the council continue to claim the ocean outfall is selected and preferred by the community.

Why the BVSC ignoring Community’s voice?
BVSC said
“Our credentials in the reuse space are significant and our experience over many years gives us the insight to know what works and what does not”
SWAMP says:
BVSC cannot claim its credentials when BVSC only recycled ¼ treated wastewater compared to other similar environment. BVSC only achieved 24% wastewater recycle, when our neighbourhood East Gippsland achieved 100% wastewater recycled/reuse.

Bega Valley Shire Council questions and answers

The following information is sourced from the Bega Valley Shire Council; the responses are the BVSC’s not SWAMP’s:

The Merimbula Sewage Treatment Plant (STP) is one of 10 that Bega Valley Shire Council owns and operates to provide safe and sustainable sewerage services to the community.
Council currently reuses about a quarter of the recycled water for irrigation at Pambula Merimbula Golf Club and Oaklands Farm. We’ve been distributing recycled water to the Pambula Merimbula Golf Club for over 40 years and irrigation to Oaklands began in 2013. The amount of reuse varies according to rainfall and in those years of high rainfall, these sites need less irrigation.
As much as we’d like to be able to, it is just not possible to reuse all of the treated wastewater because of our climate, existing land use and topography.
Council discharges excess treated wastewater through a beach-face outfall pipe on Merimbula Beach or into an area of the dunes. The area we use is significant to our Aboriginal community and is also endangered Bangalay Sand Forest; a community of over 50 endemic species including Eucalypt, Banksia, Dianella and Dichondra, among others.
The NSW Environment Protection Authority (EPA) has instructed Council to upgrade the STP and construct an ocean outfall to dispose of excess treated wastewater during high rainfall periods.
Upgrades to the plant will also improve the quality of its treated wastewater. The Merimbula Sewage Treatment Plant and Ocean Outfall Project, which has been thoroughly investigated over the past 10 years, aims to protect the area’s unspoilt aquatic and land environment and ensure public health standards are met.
In December 2017 the Community Working Group (CWG) started working with AECOM (specialist environmental consultants) to consider how the STP will be upgraded and the most appropriate alignment for the ocean outfall.

Merimbula Ocean Outfall Q&A (BVSC)
What is involved in the Merimbula STP upgrade?
Depending on the CWG’s recommendations, upgrades to the STP could include reducing nutrient concentrations, lowering suspended solids and algae counts and improving disinfection using ultra violet light.

Where does the sewage recycled at the Merimbula STP from?
We collect sewage from our communities in Merimbula, Berrambool, Pambula, Pambula Beach, South Pambula and Millingandi. The largest proportion comes from residential and holiday dwelling showers, baths, washing machines, sinks and toilets. Total average inflow to the STP is about 700 million litres per year.

What are the benefits of the upgrade to the Merimbula STP?
The upgrade will improve the quality of treated wastewater and minimise public health and environmental risks with using and disposing treated wastewater.

How did we get to a deep ocean outfall option?
The beach-face outfall has caused community concern around its impact on the aquatic environment and public health. In 2009, the EPA required Council to start investigating better disposal options. After investigating a wide range of options, Council assessed the options with a community focus group made up of state government, interest groups and local community members.
In 2013, the group and Council agreed a deep ocean outfall is the preferred effluent disposal option. Compared to other options the deep ocean outfall has:

  • the greatest environmental benefit through improving water quality and ecology
  • least construction and operational impacts recognising the value the Merimbula community places on its beach and ocean fronts
  • is more socially, environmentally and economically sustainable in the long term.

For more information about discounted options, visit: Fact Sheets 1 – 16 Merimbula Effluent Options Investigation (BVSC & AECOM 2013)

As a result, the EPA amended Council’s operating licence for the STP to include a requirement to construct a deep-ocean outfall and upgrades to the STP.

Where is the existing beach-face outfall?
The beach-face outfall has been discharging treated wastewater at the centre of Merimbula Beach since 1974. The treated wastewater flows across the beach and into the ocean waters of Merimbula Bay.
Located here:

51% of effluent from the Merimbula Sewerage Treatment Plant is discharged here, on Merimbula Beach. The remainder goes to a disused quarry in the dunes, where it exfiltrates into the groundwater, and nearby irrigation. (Source BVSC & AECOM Factsheet 2013).

Have we always had a beach-face outfall?
The original ocean outfall was commissioned in 1972 following the sewering of Merimbula, Pambula Beach and Pambula and construction of the Merimbula STP. It extended into the ocean and beyond the surf zone. In 1974 it was damaged by large seas and a temporary beach-face outfall was constructed. This temporary outfall remains in the same location to this day.

Why is an outfall needed?

  • After prolonged rainfall, the beneficial reuse sites do not have the capacity or storage to take extra treated wastewater. The excess needs to go somewhere. Currently, it is sent to a beach-face outfall pipe on Merimbula Beach (or to exfiltration ponds in the nearby sand dunes), which is not acceptable or sustainable.
  • All large sewerage schemes need a way to deal with the volume of treated wastewater unable to be reused.

Are ocean outfalls commonly used in NSW?
Coastal sewage treatment plants with ocean outfalls are very common. There are 30 active ocean outfalls along the NSW coast.

How far out into the ocean will the pipeline go?
The transfer pipeline from the STP will run mainly underground to a submerged diffuser located on the seabed up to five kilometres from the STP. The exact distance has not yet been determined.

What does a diffuser do?
The diffuser releases treated wastewater in fine jets and makes sure that the treated wastewater is effectively mixed and diluted with ocean water.

How deep will the discharge location be?
The depth of the discharge point will depend on the distance of the pipeline out to sea. It will likely be between 20 metres and 40 metres deep.

Where will the pipe be aligned?
The exact alignment is yet to be determined. The State Significant Infrastructure approval pathway has specified a limited area, which we can consider. This extends from the STP through the southern part of Merimbula Bay and offshore from Haycock Point.

Will there be ongoing assessments of the aquatic environment where the outfall is?

  • Yes, the Environmental Impact Statement (EIS) will establish an ongoing program of monitoring of any potentially impacted environment.
  • Read more about the Environmental Assessmentsthat have been undertaken so far.

What about a river outfall?
Ocean outfalls pose fewer risks compared with river outfalls because river ecology is more sensitive and the conditions for mixing, dilution and dispersion are more limited.

Could we use our existing wetlands?
There has been considerable discussion regarding the merits of wetlands to help manage and treat the treated wastewater. If the natural wetlands in the Merimbula and Pambula areas were to be utilised in some way, the outflow from them would be to Merimbula and/or Pambula Lakes and pose an added risk to oyster farming and recreation and aquatic ecosystem protection values of those lakes. The Coastal Management Act 2016 would not allow this to happen.

Could we use constructed wetlands?
Constructed wetlands require a large land area and a discharge location for water flowing from them. There is no identified available land or suitable discharge location for a constructed wetland in the vicinity of Merimbula STP. Wetlands also have variable performance due to seasonal/climatic factors and fall outside NSW EPA licencing provisions.