Where to for your Fisher Library poo?

Many have flushed a Fisher toilet, few know what happens next.

Art by Maxim Adams.

Flushing the toilets of Fisher Library usually feels like the end of a journey. But, for your newborn Number 2, it is just the beginning. By the time you walk the few steps back to your study desk, your plucky poo is already deep beneath the asphalt of Parramatta Road, having set out on a ten-kilometre journey to Bondi that will eventually take it on a grand tour of New Zealand and the isles of the South Pacific. Determined to learn what happens to our campus sewage, I set out to unearth this little-known, but much used, subterranean voyage.

I meet wastewater wizard Chris Hipsley in the Fisher Library foyer. As the University’s Fire and Hydraulic Engineer, he oversees infrastructure projects across campus, but on this June morning he is a tour guide for a half-dozen sewer-curious Honi Soit editors. Although the sewers themselves are (perhaps mercifully) off-limits to us, Hipsley is able to walk us through the first stages of the route that sewage takes from the lofty heights of the Fisher Stack to the sewer main in the streets below. Flushing Fisher Library’s Level 9 toilets injects the contents of the toilet bowl into the upper reaches of a vertical pipe which falls through the hollow dividing wall between the male and female bathrooms on each storey. Wastewater rockets straight down, completes a brief victory lap of the building’s south-east corner on Level 2, and plunges into the ground beneath the loading zone on Barff Road.

Here, waste flows into a sewer line that runs along the Victoria Park fence — just under a metre deep, according to a 1960 service diagram found in the University Archives. Hipsley leads us along the line from above, manhole covers helpfully marking out the route. The sewer heads gradually downhill towards Parramatta Road, crossing University Avenue in front of the Chau Chak Wing Museum. These are gravity sewers, which rely on a slight gradient, rather than a pump, to propel their contents. Until Bondi, it’s all downhill from here.

Hipsley takes us as far as the University’s boundary at the northwest corner of Victoria Park. It is here that waste graduates from the quaint backstreets of the University’s private line to the sewage superhighway of the Bondi Ocean Outfall Sewer (BOOS). A precipitous ten-metre slippery dip launches your fearless faeces into a 1.2 metre by 1.5 metre brick tunnel over twelve metres beneath the surface of Parramatta Road, where it begins a long traverse down Broadway.

The BOOS is a heritage-listed engineering marvel that shuttles the waste of hundreds of thousands of Sydneysiders to Bondi. Despite its near-invisibility, more people unknowingly use it every day than cross the Harbour Bridge. In the 1800s, Sydney Harbour was a fetid dumping ground for the city’s untreated sewage. Plans to intercept this waste and redirect it to the ocean were drawn up in the 1870s and the BOOS was completed by 1889, exhibiting expert brickwork and notable as the first sewer of its kind in Australia.

“The development of any great system, extending over many years and contributed to by a variety of minds, is inevitably a combination of improvisation to meet immediate needs and of planning with an eye on the distant future,” wrote T.H. Upton in his foreword to the classic 1939 volume The Water Supply and Sewerage of Sydney. Indeed, after 130 years, sludge still flows through these same brick-lined tunnels to the great, if ungrateful, benefit of thousands.

Your Fisher poo bears first-hand witness to this history as it slides down Broadway to Central Park, then beneath Central Station and Belmore Park. Bearing north-east, it passes under a few private properties before reaching a great junction at the intersection of College and Oxford streets where sludge from various branches that stretch across the city’s inner suburbs join together in a grand chamber at the southeast corner of Hyde Park.

Now united in a large oviform tunnel, the city’s collective waste flows directly eastward, initially along Liverpool Street, then beneath the well-plumbed bathrooms of Double Bay to the destination of all inner-city excrement: the Bondi Sewage Treatment Plant, in the cliffs of North Bondi.

The treatment plant is a cavernous facility buried under 40 metres of solid sandstone, hosting enormous tanks and 15 metre-high chambers. Sewage is screened for grit, plastic and other materials, before flowing into sedimentation tanks, where solids gradually settle. These days, part of your poo may also be sampled for COVID-19 testing in a laboratory, if it is lucky. The resulting sludge from the sedimentation process is scraped from the bottom and placed in digester tanks, where it is heated for days on end, and dewatered. 

The remnants of your poo, now converted into nutrient-rich biosolids, then enjoy a road trip by truck to one of dozens of farms in western New South Wales, where they are mixed with soil to help grow canola, wheat, oats, barley and pastures for animal grazing. Alternatively, they may instead be part of the 25% of biosolids that are used to rehabilitate construction sites, degraded mines, and parkland around Sydney.

For any parts of your contribution that don’t join the sludge, the ocean awaits. The opening of the original Bondi sewer outfall in 1889 cleaned up much of the harbour, but the city’s coastline was not so lucky — raw sewage now flowed straight into the ocean, metres from Bondi Beach. The completion of the Bondi treatment plant in the 1960s allowed for primary treatment of the waste, but for growing numbers of swimmers and beachgoers, if conditions were unfavourable, a day in the surf meant a day floating in wastewater.

The solution was the opening of a deep ocean outfall in 1991. A pipeline shuttles what remains of Fisher Library’s waste 2.2 kilometres out to sea, releasing it across a 512 metre-long diffuser zone, 63 metres beneath the waves. The outfall releases 130 million litres of effluent every day — enough to fill three Fisher libraries. The diluted particulate leftovers of your humble poo are picked up by the East Australian Current, eventually drifting just north of New Zealand before venturing out into the big blue of the South Pacific.

Not having a boat of my own, it is clear that if I want to visit the fabled outfall itself, there’s only one thing for it: I’ll have to swim. Determined to track this piped pathway to its bitter conclusion, I head to Bondi Beach and wade out between the waves. I do not get far before I am unceremoniously dumped and swallow a mouthful of seawater. Beating a reluctant retreat, I am grateful that, unlike bygone years, the only taste that remains in my mouth is salt. Perhaps it’s for the best that not every journey must be followed to its end.