The Sheep Wash Without a Water Balance

Tom had found himself a sheep wash.

Not one of the old concrete plunge dips Bill remembered from when he was a kid. This was a tidy bit of gear. Stainless rails, spray bars, pumps, a header tank and a covered race the sheep walked through while water blasted the mud, manure and dags out of the wool.

It had come from a property down near the coast.

Tom had gone to have a look at it before buying it and reckoned the whole arrangement was pretty impressive. Water came from a big tank beside the yards, passed through the wash, then disappeared through drains beneath the race. The dirty water ran into a settling sump, where the heavier muck dropped out, and from there a pump sent it away to the farm's treatment pond.

Nothing fancy.

But everything had somewhere to go.

Bill had gone down with him the second time, mostly because Tom wanted another opinion and partly because Dog had already climbed into the ute and refused to get out.

Bill walked around the wash, looked at the pumps, followed the pipes and opened a couple of inspection lids.

"Good setup," he said.

That was enough for Tom.

Two weeks later the whole thing was sitting beside Tom's new sheep yards.

The wash race was bolted down. The tank was plumbed in. The pumps were wired. Tom had even poured a neat little slab around it.

Dog had installed his own piece of infrastructure beside the shed: an old stainless-steel water bowl in the shade.

Bill arrived just as Tom was finishing the last connection.

"Looks good," Bill said.

"Exactly the same as the old place."

Bill walked around the back.

A length of pipe came out from under the wash race, ran along the concrete for a couple of metres, and stopped.

Bill looked at the pipe.

Then he looked at Tom.

"Where's that go?"

"That's the outlet."

"I can see that."

Tom waited.

Bill pointed at the open end.

"Where's the water go?"

Tom looked at the pipe as though the answer might be written on it.

"Well. Out there."

Bill looked across the paddock.

"Out where?"

Tom frowned.

There had been a sump at the old place.

And beyond the sump there had been a pump.

And beyond the pump there had been a treatment pond.

None of those things had arrived on the truck.

Tom stared at the end of the pipe for a bit longer.

"Could put a tank there."

"You could."

"So that's fixed."

Bill nodded.

"Until the tank's full."

Tom scratched his chin.

They found an old thousand-litre tank beside the machinery shed, dragged it over and connected the outlet pipe.

Then Tom filled the header tank.

He reckoned there was no point solving a problem until they knew how big it was, which Bill thought was a surprisingly sensible position right up until Tom opened the gate and ran twenty sheep through the wash.

The machine worked beautifully.

The sheep went in dirty and came out wet and considerably cleaner.

The water came out the other end brown.

Not mildly brown either.

It carried mud, bits of wool, manure, grass seed, grease and enough miscellaneous sheep material that Dog took one sniff and backed away.

The tank began filling.

Half full.

Three-quarters.

Then almost to the top.

Tom was watching the sheep.

Bill was watching the tank.

Dog was watching both.

The first brown trickle came over the rim.

Dog stood up.

Another followed it, running across the concrete toward the shed.

Straight toward Dog's water bowl.

Dog looked at the advancing brown tide, looked at Tom, then picked up his bowl by the rim and carried it several metres up the hill.

Bill watched him go.

"Dog's done his water management plan."

Tom spun around.

The tank was overflowing.

"Bugger."

He shut the pump down.

Brown water continued dribbling across the slab.

Dog put his bowl down safely above the high-water mark, drank from it, and lay beside it.

Tom stared at the overflowing tank.

"Need a bigger tank."

"You could get one."

"So that's fixed."

Bill looked at him.

"For longer."

Tom sighed.

They pumped some of the dirty water back through the sheep wash.

Tom brightened immediately.

"See? Recycle it."

"Yep."

"Save water."

"Yep."

They ran another batch of sheep.

The water came back.

It was still brown.

Possibly browner.

Bill poked a floating lump of something with a stick.

"It won't get cleaner."

Tom had another idea.

"Wheel wash."

Bill nodded.

"Wash the ute and trailers with it."

"Yep."

"That's useful."

"It is."

Tom waited.

Bill didn't say anything.

Tom sighed.

"And then where does it go?"

Dog lifted his head.

They considered spraying it onto the paddock.

That raised the question of what was actually in it, how much they would be spraying, where it might run if it rained and whether repeatedly putting the concentrated muck in one place was such a terrific idea.

They considered an evaporation pond.

That sounded better until Bill asked how big it needed to be, what happened after three wet weeks, and what would be left behind once the water evaporated.

They considered an even bigger tank.

That solved the problem for longer.

Dog looked at his bowl.

It did not solve the problem.

Tom suggested carting the water away.

Bill agreed that would work.

"Where to?"

Tom didn't know.

"And in what?"

Tom pointed at the truck-and-dog they used for sheep feed.

Bill looked at the tipper body.

Tom looked at the tipper body.

Dog looked at both of them.

"Right," Tom said.

They would need a tanker.

Unless, Tom reasoned, they could take dirty water back on the same trips that brought something else in.

Bill liked that better. At least then they would not be running empty trucks both ways.

But they still needed a tank, a pump, a tanker that could legally carry the stuff, somewhere willing to receive it, and enough storage to keep the sheep wash operating when the tanker couldn't come.

Tom sat down on the rail.

"This was a perfectly good sheep wash when I bought it."

"It still is."

"Then why has it turned into such a bloody complicated thing?"

Bill leaned against the gate.

"Because you bought the machine."

Tom looked over.

Bill pointed vaguely south, in the direction of the old property.

"The system was bigger than the machine."

Tom said nothing.

"At the old place, water came in from somewhere. Dirty water went somewhere. There was a sump, a pump and a pond. Somebody had worked out how much water it used and what happened to the muck."

Bill pointed at the shiny new wash beside them.

"You moved the bit in the middle."

Tom looked at the tank.

Dog's bowl was still sitting safely uphill.

"So what do I do?"

Bill shrugged.

"Plenty of things you can do."

"You can recycle some. Evaporate some. Treat some. Cart some away. Build enough storage to cover the days when something isn't working."

He nodded toward the dirty water.

"But whichever way you do it, you need to work out how much goes down every path, what's in it, what happens to the muck, and where the water finally leaves the system."

Tom watched another piece of wool drift across the tank.

"And until I do that?"

Bill pushed himself off the gate.

"You haven't got a water system."

He headed toward the ute.

"You've got a sheep wash with a pipe sticking out the back."

Dog picked up his bowl again and followed him, apparently unwilling to take any chances.

Tom stood beside his immaculate new installation.

Everything that had arrived on the truck was working perfectly.

That, he was beginning to understand, wasn't quite the same thing as having a working system.

The Water Has to Go Somewhere

There is a simple problem buried inside the Glan Devon biosolids proposal.

The plant takes wet biosolids, dries them, and turns the dried solids into fertiliser. In the process, it removes roughly four to five tonnes of water every operating hour.

That water does not cease to exist.

And between the February 2026 version of the project and the revised Glan Devon concept presented in May, the clearly defined pathway for that water disappears.

That is the gap shown in the diagram.

In February, the water balance made sense

The February information included an Andritz budget proposal for the biosolids dryer. It was originally prepared for Caboolture, so it is not a final Glan Devon design, but it is important because it shows a complete water pathway.

Wet biosolids entered the dryer at around 18 per cent solids, and about 4 tonnes of water an hour were evaporated. The exhaust then passed into a direct-contact condenser/scrubber, which also received about 95 m³/h of WWTP effluent as cooling water.

This system produced roughly 99 m³/h of mixed condensate and process water, which had a clear destination:

the sewage system.

So the February logic was simple and complete:

water in → dryer → condenser → wastewater → sewer.

There was both a source and a sink.

Then the project moved to Glan Devon

Glan Devon is not a wastewater treatment plant, and there is no sewer connection available to accept ~100 m³/h of liquid.

By May, the system had changed. The dryer still removes about 4.9–5 tonnes of water per hour, but the defined outlet for that water is no longer present.

Instead, the documents refer to process water and condensate reuse, with potential uses such as wheel washing, equipment washdown, and cooling.

Individually, these are reasonable engineering ideas. Collectively, they do not yet define a final destination.

The key question remains unresolved:

Where does the water ultimately go?

The nature of the water has not been defined

It is important not to assume the dryer produces clean distilled water.

The February design shows why. The condenser is a direct-contact system, where cooling water is sprayed into the exhaust stream. This means the resulting liquid is a mixture of:

• condensed water from biosolids evaporation;

• process cooling water; and

• captured particulates from the exhaust gas.

For Glan Devon, the actual composition is unknown, because no representative condensate analysis has been provided.

Dryer exhaust may carry volatile or condensable compounds in the gas phase, together with entrained droplets, aerosols and particulates. Depending on partitioning, the resulting process water could therefore contain ammonia, salts, organics, metals, PFAS and other biosolids-derived contaminants. The actual concentrations are unknown because representative condensate data have not been provided.

Without data, the condensate cannot be assumed to be clean, nor can it be assumed to be highly contaminated. It simply must be treated as uncharacterised process-derived water requiring definition before reuse or disposal is determined.

Reuse, cooling, and disposal are not separate solutions

The May concept suggests multiple possible pathways for this water, but they are often discussed as if they are independent solutions. In practice, they are interconnected parts of a single mass balance.

Reuse

Water can be reused for internal purposes such as washdown or cooling, but reuse only delays disposal. It does not eliminate water from the system. Any reuse loop will accumulate contaminants unless there is a defined purge or loss stream.

Cooling systems

An evaporative cooling tower could provide a genuine water sink through evaporation. However, this introduces a second mass balance:

• water is lost to the atmosphere via evaporation and drift;

• dissolved and non-volatile substances remain and concentrate;

• a blowdown stream is required to control buildup.

So the cooling tower does not eliminate the water problem; it redistributes it into:

• atmospheric emissions (vapour and drift), and

• a concentrated liquid waste stream requiring disposal.

Importantly, the cooling tower is currently treated as a noise source, not an air-emissions source, in earlier assessments. If it becomes a major pathway for process water, that classification gap becomes significant.

Off-site disposal

Off-site transport of process water is also feasible in principle, but it is not currently defined in the project design.

At ~4–5 t/h, the plant produces roughly 32,000 tonnes of water per year. This would require on the order of 900+ tanker movements annually (depending on load assumptions), plus return logistics.

However, the current design describes truck-and-dog tippers for biosolids, not liquid tankers, meaning a liquid export system would require new infrastructure, regulatory classification, and transport arrangements.

Off-site disposal is therefore not a minor adjustment; it is a fundamental change to the logistics and traffic model.

The Xetrov pathway is not a complete water solution

The May documents also suggest that dryer steam or off-gases may be directed to the Xetrov thermal unit.

This is technically plausible, but it does not resolve the water balance.

If 4–5 t/h of water remains in the gas stream, the Xetrov must heat a significantly larger gas load. This has implications for:

• combustion temperature and stability;

• oxygen demand;

• residence time;

• heat balance;

• stack flow and moisture;

• and air pollution control performance.

A simple sensitivity shows that heating this steam to operating temperature is not negligible relative to the stated thermal input of the system.

More importantly, this represents a change in operating conditions compared with those assumed in emissions modelling, meaning the validity of existing test-based assumptions must be demonstrated under the revised gas composition.

Storage is only a buffer, not a solution

At 4–5 t/h, the system generates approximately:

• 96–120 m³/day, or

• 672–840 m³/week.

This is far beyond the scale of the conceptual stormwater storage shown in the proposal (~120 m³).

Storage can manage short-term imbalance or outages, but it cannot absorb continuous production. It is a buffer, not a sink.

The system therefore requires a defined sink

Across all options—reuse, cooling, off-site transport, Xetrov integration, and storage—the same conclusion emerges:

water is being moved, transformed, or delayed, but not yet given a fully defined final exit pathway.

A complete system must show:

• where water is permanently removed from the site balance;

• or how evaporation and discharge are quantitatively controlled;

• or how off-site removal is reliably achieved.

Without this, the system is not closed.

The project likely requires multiple pathways working together

A realistic design may combine:

• condensation and recovery;

• internal reuse;

• evaporative cooling with controlled blowdown;

• off-gas integration with the Xetrov;

• off-site liquid export; and

• storage for operational variability.

This is not inherently problematic. The issue is that the integration has not been demonstrated as a single mass-balanced system.

The governing equation remains:

water in = water out + change in storage

And it must hold under all operating conditions, not just nominal averages.

Before this can be considered a bounded system

The engineering challenge is not the absence of solutions, but the absence of a defined, integrated one.

To resolve this, the project must clearly define:

• the full water input stream;

• the fate of evaporated water (gas vs condensate split);

• the composition of process-derived water;

• the true capacity of reuse systems;

• the cooling tower design and blowdown pathway;

• the impact of dryer steam on the Xetrov system;

• the ultimate liquid disposal route (evaporation, discharge, or off-site transport);

• and the required storage for operational resilience.

Until these are defined in a single coherent mass balance, the system remains incomplete.

The February design had a clear destination for water.

The May design does not yet replace it with an equivalent one.

The water has not gone away.

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