Project: Neerabup Resource Recovery Facility

Location: Neerabup, Perth, Western Australia

Asset Owner: SITA Environmental Solutions

Date: February – November 2008

Scope: Fabrication, assembly and transportation of two composters

RCR Construction and Maintenance Welshpool operation was also contracted to assemble, align and weld the two composter halves together at the Neerabup site. The two drums together are more than 65 metres long and are able to hold more than 420 tonnes of waste at any one time.

The composter works in a similar way to a backyard composter, but on a much larger scale.  General household rubbish is loaded into the front end of the composter. Waste then travels through the length of the composter over a three day period and is composted using an aerobic digestion process.

The waste travels through the Resource Recovery Facility for approximately one month, where it breaks down and decomposes at an accelerated rate. After the rubbish passes through the composter, it continues to Primary Refining, Sorting, Secondary Refining and then to the Maturation Hall. The recyclable items such as steel, glass, rags etc are removed during this stage and are sent to external contractors for processing.  Plastic is also removed as this is unable to be processed.  The waste is then regularly turned over a 28 day period through the Maturation Hall to produce the market quality compost that is despatched to companies for use as an organic soil conditioner.

The two composters were fabricated from 320 tonnes of plate and forged materials, sourced from Western Australia, the east coast of Australia and Korea. The 25mm – 75mm thick and 14.5m long sheets of steel were cut, prepared and rolled to form the cylinders prior to welding. The cylinders were then welded together with sub arc welding.  Welding was ultrasonically tested to thoroughly check for welding defects or cracks, no failures were recorded.

Special tyres were manufactured and shrunk to fit onto the fabricated composter shells following machining in order to ensure an interference fit. Cylindrical pivot trunnions were incorporated into fabricated drive bases which were used to mount the composter on site.

Due to the size and logistical challenges in moving the equipment, the composter was built in two halves at the RCR Welshpool facility.  The halves were then transported to the Neerabup site along a carefully planned route which required assistance from the WA Police and an escort by Western Power. The sections of the composter were individually delivered on a six hour road trip to its destination at Perth’s new $80 million waste management project site by a purpose-built, 128-wheeler to transport the 160 tonne cargo from Welshpool.

The acquisition and completion of the composter project has been a great success for RCR. This can be attributed to close working relationships between the RCR Engineering divisions - Fabrication, Engineering, Heavy Machining and RCR Construction and Maintenance. The integrated team approach resulted in RCR being able to complete the job without outsourcing, allowing RCR to ensure the composter was delivered on time with a high quality of workmanship.

The first stage of the planned three-stage Resource Recovery Facility was constructed on a 10 hectare site in the Neerabup Industrial Area. The facility will treat up to 100,000 tonnes of household waste annually and convert about 70 per cent into market-quality compost.  The facility, operated by BioVision 2020 and jointly-owned by SITA Environmental Solutions, is expected to be producing compost in the first half of 2009.

Site Work

Installation of the composter involved establishing four off drive base assemblies. Each concrete plinth was surveyed to confirm its elevation and the hold down bolt’s location. The drive bases were then positioned for installation and levelled using shim plates.

After the correct location was assessed, support frames were erected to ensure the composter would be level when lifted into position.  The two composter sections were placed and aligned on these support frames, tacked together and internal gusset plates fitted to allow the assembled composter to be rotated on the two drive base assemblies.  The composter halves were then welded together.

Numerous checks were undertaken throughout the installation, which included a recheck of the alignments,  adjustment of the drives to ensure the composter does not ‘walk’ during operation and confirmation that all rotating equipment was correctly lubricated.

Lastly, all of the periphery equipment such as end plates, gates, chutes and platforms were installed.

Other assessments include the ‘dry’ and ‘wet’ commissioning operational checks and testing.