Completed June 2025. Perfect Contracting delivered the tank farm demolition and site remediation works for Cleanaway at its former liquid waste treatment site at 10 to 12 Waynote Place, Unanderra, south of Wollongong. A shed full of steel and plastic process tanks, reactors, pumps, overhead pipe racks and an exhaust stack came out over five weeks, and the site was handed back clean, with the client signing off the scope as complete on the last day.
Perfect Contracting won the work through a competitive tender and was engaged directly by Cleanaway under a Minor Works Agreement. It was the first of several Cleanaway sites the company has since worked on.
Services delivered
- Pre-start inspection of every tank and line to confirm isolation and decontamination by others before any cutting
- Gas testing around pipes and tanks before hot work
- Removal of mechanical and electrical services, overhead racks and pipework by hand from elevated work platforms
- Cutting and processing of plastic tanks with a 20 tonne excavator
- Demolition of the vertical steel tanks and reactors, held from the top with a shear attachment while the legs were cut, then lowered and processed
- Hot work permits, fire watch and oxy cutting of tank shells in an isolated processing area outside the shed
- Removal of the exhaust stack by mobile crane, cut down in sections from two elevated work platforms
- hazardous materials removal: lead paint removal from tank and steel surfaces under controlled conditions before cutting
- Cleaning of concrete bunds and pits, and pump out of residual liquids for tracked removal
- Segregation of steel for recycling, with plastics and contaminated material to licensed facilities
- Final clean of the shed floor and yard, and handover
The challenge
The Unanderra site had been a liquid waste treatment plant. That means tanks that once held oily water and process liquids, reactors, pipework running in every direction overhead, and bunds and pits with residue in them. Cleanaway had decommissioned and cleaned the tanks before we arrived, but on a site like this you treat nothing as clean until your own supervisor has inspected it and the gas monitor says so.
The tanks were tall, thin walled and close together, inside a shed with a roof not far above them. There was no room to swing a machine at them. Some carried lead paint. The exhaust stack stood well above the roof line and had to come down without touching the shed. And the site sat inside a working Cleanaway depot, with the client's trucks and staff moving around the fence line every day.
Perfect Contracting's role
Perfect Contracting was the head contractor to Cleanaway for the demolition and remediation package. Our estimating team priced the job, our bid team negotiated the agreement, and a Perfect Contracting supervisor ran the site from day one to handover with a crew of five to seven and our own plant: 20, 30 and 35 tonne excavators, a skid steer and elevated work platforms.
The demolition methodology was written by us before the first tank came down and set out what stayed, what went, and in what order. Cleanaway's site representatives signed the daily site diaries, so both sides knew exactly where the job was every day.
How the tanks came down
Work started at the top. The crew took down the mechanical and electrical services and the overhead pipe racks by hand from elevated work platforms, so that nothing was hanging over the tanks when the machines moved in. The plastic tanks were then cut up and processed with the 20 tonne excavator.
The vertical steel tanks and the two reactors were the main event. Each one was held from the top with the shear attachment while the legs were cut, then lowered to the floor under control. The smaller tanks were pushed over to ground level. Nothing was dropped free. Once down, the tanks were carried out of the shed to an isolated processing area in the yard, where the oxy cutting happened under hot work permits, with a fire watch and a gas test before every cut. Cut sections went straight into the scrap truck.
With the shed empty, the exhaust stack was the last structure standing. A mobile crane held it while the crew cut it into sections from two elevated work platforms, one cutting and one rigging, and each piece was lowered to the ground and taken to the processing area. Then the bunds and pits were cleaned out, the floor was washed down and the site was handed back.
Environmental controls
- Residual liquids pumped out of tanks, bunds and pits and removed as tracked waste before any cutting
- Lead paint removed under controlled conditions with signage and exclusion zones before hot work on painted steel
- Steel and pipework segregated and sent to a metal recycler, plastic tanks and contaminated material to licensed facilities
- Hot work confined to an isolated processing area outside the shed, fire extinguishers and water on hand
- Fenced exclusion zones and signage separating our works from the operating depot
- Every load off site recorded on the daily site diary and signed by the client
Safety on a tank farm
Tank farm demolition is a permit job. Every day started with a pre-start meeting and a documented site inspection. Hot work permits and working at heights permits were issued and closed each shift, and a gas test was taken around the pipes and tanks before any cutting started. Elevated work platforms were used for all work above the floor. Nobody worked under a suspended tank, and the exclusion zone around the processing area was held while the excavators and the scrap truck were moving.
The methodology gave the crew a sequence, and the supervisor stuck to it. When the site was fully cleared, the last site diary of the job reads that the scope of work was 100 per cent complete, signed by the client's supervisor.
Industrial demolition in the Illawarra
The Illawarra has a lot of this kind of work coming. Old process plants, tank farms, workshops and warehouses around Unanderra, Port Kembla and Wollongong are being cleared for new industrial uses or handed back at the end of a lease. Perfect Contracting runs industrial demolition in Wollongong, plant decommissioning and tank and vessel demolition across the region from its Sydney base, with the same supervisors, plant and permit systems used on this job.
The outcome
Five weeks on site. Tanks, reactors, pipework and the stack gone, bunds and pits cleaned, floor washed down and the site handed back to Cleanaway with the scope signed off as complete. Since Unanderra, Perfect Contracting has gone on to deliver demolition and remediation work for Cleanaway at other sites in New South Wales.
See more Perfect Contracting projects or contact our estimating team.
Perfect Contracting acknowledges the Aboriginal and Torres Strait Islander people as Traditional Custodians of the country on which we live and work. We pay our respects to the Traditional Custodians and Elders past, present and future, and honour their connection to the land and ongoing contribution to society.