Rocky Hill Recycled Sand and Soil composting processor Richard Williams and manager Tammi Thrower in front of a windrow, which generates enough heat to eradicate weeds and seeds. The mix will eventually be sold in bulk to replenish and rejuvenate gardens. Photo: John Thistleton.
Most gardeners use a wheelbarrow to top up their compost heap. Richard Williams, the son of a legendary Goulburn nurseryman, uses a freight train.
Tonnes of food and garden waste Sydneysiders dump into their green bins comes by train to Tarago, along with even more general waste collected in red bins. The general waste is tipped into the old Woodlawn mine void. But the FOGO (food organics and garden organics) is processed and trucked into Goulburn.
And the city can’t get enough of it. Packed with nutrients, it’s the magic ingredient in eco soil produced at Rocky Hill Recycled Sand and Soil.
Rocky Hill recyclers have produced tonnes of cost-effective eco soil for landscapers laying turf, backyard growers perking up their veggie patches, and local governments across the Southern Tablelands and Highlands.
Gardeners, mowing contractors, tree pruners, handyman services and landscapers bring much of the green waste in for processing at Rocky Hill’s large Hetherington Street site.
Richard Williams puts it all through a chipper first, and with a giant loader pushes it into three-metre-high windrows. Then pasteurisation occurs, heating the broken-down waste and baking it in 60–70-degree temperatures.
“We also add water to it — that helps it heat up and kills any weed and seed,” Richard said.
He is continually turning the windrow edges into the middle of the heap to bake it all evenly.
“I like to leave it for a minimum of three months, from the time it is mulched to the time we screen it,” he said.
Manager Tammi Thrower said the well-baked waste was run through a trommel screen to separate finer material. Anything smaller than 14 millimetres was separated and called ‘’fines’’.
“We’re mulching and then composting. We have three windrows going most of the time. We have always got the result (eco soil) there ready to go,” she said.
Multinational waste manager Veolia has a similar breaking-down process at Tarago for the FOGO. Moving over a conveyor belt, the waste is picked clean of any plastics or other unsuitable items before being chipped, mulched and windrowed.
Veolia’s fines are 8 mm, much finer than Rocky Hill’s 14 mm fines. About 40 tonnes a week is trucked into Goulburn to the soil and sand recyclers.
“We buy it as an additive,” Richard said. “We have what we call our eco fines, which is the product after it has been screened. Then they have their fines, then we buy it and mix theirs with ours with recycled topsoil and a bit if coarse sand.”
Coarse sand comes from a quarry near the Lachlan River at Dalton, and a Sydney company supplies the recycled topsoil, known as virgin excavated natural material (VENM), such as natural soil, rock, clay, or sand.
Mixing all these materials is like making a dry cake mix with a big spoon, says Richard, who inherited his passion for healthy gardens from his father, Graeme Williams. More than 30 years ago, Graeme owned Thomas Williams Garden Centre on Sydney Road, Goulburn, and before that, a nursery at Crookwell.
Aiming to keep waste out of landfill, Rocky Hill recycles plasterboard scraps into gypsum for farmers, and broken-up concrete into road base. Of several varieties of soil it sells, eco soil is a top seller, according to Tammi.
Like the stone tower at the top of the hill it is named after, Rocky Hill Recycled Sand and Soil has deep roots into Goulburn.
The business began when Keith, Max and Bill Burgess began carting sand. Years later, they sold their venture to the Wybrow family, who sold the site to the Divall family in February 2021.
Divalls had extensive experience composting, and the Rocky Hill venture began refining the operation and adding many more customers to the long-term Divall clientele.
Tammi, the third member of her family to work for Divalls, is stoked with the role eco soil plays in keeping waste out of landfill and its acceptance in the market.
“Everyone loves it, especially with the FOGO, because there’s so many nutrients in it,” she said.
”It’s very light and fluffy. They’re getting good results. The turf and garden beds are doing beautifully well.”
