Byron sewerage systems overloaded, says former councillor

Paul Bibby

Lying just beneath the Shire’s green and leafy surface, a giant, unwieldy beast creaks and groans.

With every new house, unit or secondary dwelling, it quietly grows, gaining another set of tentacle-like pipes.

Such is the nature of the sewerage system beast that most of us are content to simply flush and forget until something goes wrong.

But the reality is that our sewerage system has become an overburdened animal that chews through large amounts of electricity and is, in some places, significantly overloaded.

Byron Shire Council did not answer any of The Echo’s questions about the sewerage system when contacted last week, so we dug into the issue ourselves.

We found Council documents which show that, despite millions of dollars worth of works in recent years, the system is facing major challenges on multiple fronts that are set to become more acute as new residential developments begin to rise.

Alternative approaches

Duncan Dey, a civil engineer specialising in water and a former councillor, believes it is time to consider alternative approaches.

‘We need to look the current scenario in the face and say, “if we’re going to double our population, do we really want to double the size of our urban sewerage systems?”’ he says.

‘I believe we need to look at alternatives such as non-sewered systems of dealing with wastewater.’

‘We can’t keep on like this forever.’

Perhaps the most concerning aspect of the Shire’s sewerage system is the amount of energy it consumes and the greenhouse gas emissions this creates.

Power hungry

According to a recent emissions report prepared by Council staff, the Shire’s waste water treatment systems used 3,764,502 kWh of electricity during the 2016/17 financial year.

That represents 65 per cent of the council’s total electricity use for that period.

It translates into 3,162 tonnes of greenhouse gas emissions – that’s the equivalent of 670 typical passenger vehicles running for one year.

The Council report also goes on to say that the amount of power being used by the sewerage system is increasing.

‘For example, the West Byron Sewage Treatment Plant had a 128,947kWh increase between 2015/16 and 2016/17,’ the report states.

But the emissions produced by the sewerage system’s power use are dwarfed by the so-called ‘fugitive emissions’ it creates.

Fugitive emissions are the emissions that occur as a result of the organic matter in our waste decomposing as it is treated.

The Shire produced 8,955 tonnes of fugitive emissions last financial year, up by nearly ten per cent from the previous year.

When considered as a whole, the Shire’s sewerage system is responsible for 34 per cent of the Council’s total greenhouse gas emissions.

Footprint reduced

Mr Dey believes reducing the system’s footprint is the most pressing issue.

‘The first step has to be figuring out how we can reduce the amount of energy used,’ he says. He supports Council’s proposal to harness the fugitive emissions through bioenergy facilities at the Brunswick Valley and West Byron Sewage Treatment Plants (STPs) and to partly power the former facility through solar panels.

However, the argument for alternative non-sewered solutions remains compelling, particularly when Council’s rate bills start hitting ratepayer letterboxes.

Higher cost than other councils

According to a draft water supply and sewerage report prepared for Council late last year by Hydrosphere Consulting, the typical sewerage charge for a residential property in the Byron Shire is $1,149 – significantly higher than for any other shire in the northern rivers.

This charge, which includes a fixed charge and a metered residential usage charge, reflects the high cost of running and maintaining the urban sewerage systems.

Council’s most recent budget estimates that it will have to spend $11.25m to run the system this financial year, with a further $6.51m needed for new works.

Council’s Sewer Fund, which bears this burden, has been forced to borrow extensively over the past decade.

The most recent budget indicates that the fund is in debt to the tune of $47,759,649, though three years ago it was significantly higher.

Infiltrated and overloaded

A major contributor to the cost of running and maintaining Byron’s sewerage system is the infiltration of stormwater and groundwater.

In older, more established areas such as Mullumbimby, a significant proportion of the rain that falls onto people’s roofs and gardens ends up in the sewerage system, rather than the stormwater system as is intended.

The draft water supply and sewerage report indicates that during heavy rainfall events the flow into the sewerage system is 15 times higher than in non-rain times.

Mr Dey says this is largely the result of illegal or substandard plumbing within both private properties and the public system in Mullumbimby.

‘Every time there’s an extension to an existing house or a secondary dwelling, or even a substantial piece of landscaping, the plumber comes in and says to him or herself: “Okay, where is the water from the roof going to go?”

‘And unfortunately they often just identify the most accessible collection point because it’s the easiest way to get the job done.

‘What you end up with is all of these downpipes and drains going straight into the sewerage system rather than the stormwater system, so when it rains heavily, all of that water ends up at the sewage treatment plant and gets processed as sewage.’

According to the draft report, there is also a significant amount of groundwater infiltrating the sewerage system.

While there are little data regarding the extent of this infiltration, it is thought to occur via the porous and in some cases cracked and degraded clay pipes that are still in use in and around Mullumbimby.

Brunswick River affected

These dual forms of infiltration are overloading the Brunswick Valley STP, which caters to the large area in and around Mullumbimby.

The so-called ‘hydraulic loading’ at this plant is more than triple the design standard during non-peak dry weather, according to the draft report.

Referring to a previous risk assessment, the report notes that, because of this very high hydraulic load, ‘the risk of inadequate treatment of pathogens… suspected solids and chemical contamination is very high’.

The impact is felt by the Brunswick River, which the vast majority of the treated waste water goes into.

While significant works undertaken by Council over the past decade have resulted in a 15 per cent reduction in overflow incidents and a 39 per cent reduction in overflow volume, the Brunswick Valley STP remains very much under the pump.

OS STP operating above capacity

Around the corner, the Ocean Shores STP is already operating well above its capacity according to the draft report, with population growth set to place even greater pressure on the system.

The council is now facing the prospect of a $30m redevelopment of that plant, or running the sewage to Mullumbimby, which would have to be significantly upgraded to meet the demand.

The prospect of further large residential developments in West Byron and Mullumbimby is enough to have any water engineer quaking in his RM Williams boots.

Mr Dey believes it adds further weight to the argument for a non-sewered solution such as the onsite systems currently being used in  rural-residential areas like Ewingsdale.

‘It means you capture the sewage coming out of your house at your house,’ he says.

‘You run it through a treatment system and, once processed, it goes into the backyard.

‘It means the backyard has to be bigger than the house itself, which bucks the trend of big houses and tiny yards that we seem so attached to, but I think we have to really ask whether we want to keep going in the direction we’re going.