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Meet the staff – the Prep Lab

In last month’s issue we met Issy Purwanto, who is the first point of contact for your samples at the lab. After Issy enters all the details in the system, the samples go off to the Prep Lab. In this article we meet the technicians there who prepare your samples for analysis and run the first tests.

What we refer to as the Prep Lab in fact consists of four separate rooms, each equipped for different tasks, dependent on the tests you specify.

Currently we have four technicians working in the Prep Lab. Although their responsibilities overlap and all can substitute for one another, each one looks after a particular area.

The most senior technician by experience is Andrew Sheldon. Andrew joined SESL last year after 12 years working in a coal prep lab in Newcastle. Andrew looks after sample drying, subsampling, pulverising and sieving. Samples that may contain asbestos, like recycled soils, wait while an outside lab tests for asbestos. If asbestos is reported, the samples are discarded, and the client is informed. Most samples receive the all-clear.

In the Pulverising Room, various drying ovens dry plant tissue samples at around 40 °C for later extraction, while others dry soil samples at 40 to 50 °C, generally overnight. Soil samples must be reduced to powder for chemical extraction. Andrew takes a sample of about 50 g and places it in the ring mill. This is a cylindrical container made of ultra-hard zirconia ceramic, which houses a smaller, loose zirconia ring and a central, loose zirconia puck. The container, with its lid, is clamped inside the pulveriser machine, which then shakes everything rotationally for 15 to 20 seconds. The result is a fine, dry powder.

Wood chip and compost samples go through the chipper, a machine that grinds the samples through a coarse mesh to reduce the particle size to a standard size for analysis.

In the same room, Jesse Fenn looks after T276 testing. This RTA test concerns the presence of foreign materials in samples. Any foreign materials – plastic, glass, metal etc. – are sorted by hand, weighed and reported back to the client. Jesse also looks after sample weighing and centrifuging of soil-in-water samples.

Jesse was trained at SESL under the administration of the NSW Vocational Education and Training Accreditation Board, and holds a Certificate IV in lab work.

In the Wet Lab, Josh Shaw looks after Australian Standard tests 4454 (Composts, soil conditioners and mulches), 4419 (Soils for landscaping and garden use) and 3743 (Potting mixes), testing samples for their compliance with parts of those Standards. Josh is also responsible for carbon, sulphur and organic matter testing in an induction furnace, and the testing of physical characteristics: bulk density, particle size distribution and solid contaminants content.

Josh also looks after toxicity testing, sowing radish seeds in growing medium samples and then measuring root lengths after 4 days. The degree of root length reduction against a standard determines whether any samples are phytotoxic.

Josh has been with SESL since last year, and is being trained as a lab technician under a TAFE Certificate III program. Josh aims eventually to study at university to further his scientific knowledge.

Finally in the Prep Lab, Harry Leake helps out when he is needed. Harry, Simon’s son, is gradually being trained in all jobs at the lab, with the ultimate aim that he can substitute in any role when needed. Harry is also studying programming through the University of New South Wales so he can administer SESL’s database.

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