For the Serra family, having a versatile drill rig is necessary for the region and the type of work they do. The multi-generation family business is located on the fertile Atherton Tablelands of northern Queensland, Australia, and the T4W drill rig is its workhorse, drilling boreholes for agriculture, residential and mining customers.
Before his family started the business in the late 1960s, Joe Serra says if you needed a well drilled, you’d put your name on a list with a drilling company that would come around occasionally. His father saw a business opportunity – and he was right.
Serra admits that when his father started the business, he bought the wrong rig. It was a mud-rotary rig that didn’t work in the varying formations of the Tablelands. In 1981, they bought their first used T4W, and that gave them the hard rock power they needed, and they’ve stuck with the T4W ever since.
After 30 years of running T4Ws, the family recently purchased its newest rig. “The old rig was running great, but with the incentives offered by the government, it didn’t make sense not to buy now,” explains Serra. The Australian government offered tax incentives to make capital expenditures at the time.
Today, the family business drills water wells for irrigation and drinking water, while also doing work for mines in the region. Serra likes the versatility of the T4W that allows him the finesse to drill 620-foot water wells – including running 118 feet of slotted PVC casing at the bottom – and the strength to drill 950 feet of steel casing in the coal-mine region.
The distance the family drilling business will travel has grown over the years. Population and farming development has levelled off. So Australia’s mining industry has developed into a good base for the Serra business. Within a day’s drive, coal fields and metals mines offer an alternative source of revenue drilling for ground monitoring, dewatering and chip sampling.
In the Tablelands near the family farm where the Serra family got its start, the ground is rich with volcanic surface soils that make the region perfect for everything from bananas to potatoes. The land once was a tropical jungle that was cleared in the first half of the last century. Below the surface is honeycombed basalt rock that holds a large amount of water. Below that is solid granite.
Serra gives an example of the formation: Two feet of surface soils, 20 feet of sub-soils, 200 feet of clays, 80 feet to 90 feet of decomposed or 50 to 60 feet of honeycombed igneous rock. “When going through the decomposed formation, it’s important to slow down,” he cautions. Although it’s fast drilling, the ground can swell behind the hammer, causing it to become trapped below the expanded ground. Serra says going slow allows the formation to move with the hammer, and not swell after penetrating the formation.
At times, they also encounter sandstone below the volcanic rock, but once the tight granite is reached, there will be a low water yield.
Serra talks about one situation that other drillers might encounter. On a mine property, he says they were getting half the expected life out of their hammers. After looking at all possibilities, he found that it came down to the water they were injecting. The minerals in the water were caustic, reducing the piston life. The solution was to bring water from off-site to fill the tank.
After so long on the job, trouble-shooting has become second nature to Serra and the rest of the family – similar to most drillers. And similar to many drilling firms, the Serra family has been at it for three generations.