It’s not an easy task to dig a hole down through layers of soil, limestone, sandstone and shale to reach the layers of gravel and sand that catch and store water underground.
Even in earliest human history, it became obvious that the water in surface streams, rivers and ponds would not be enough to supply everyone. So people started digging wells. The Bible says that Moses smote the rock with his rod and fountain of water burst from the ground. Archaeological evidence shows us that the ancient Persians, Egyptians and Chinese built wells to tap groundwater.
Those ancient wells were dug by hand, a laborious and dangerous task. As the wells got deeper, the walls were in constant danger of caving in. It could take weeks, months or even years to build deeper and deeper wells.
In the 40s, the technology finally caught up with the need.
Before World War II, augers had been used to drill shallow wells, but there was a limit to how far down an auger could be turned and the walls of the hole were not supported as the well was dug. In another technique, a hollow “drive point” was hammered down through the rock until it hit water. But the drive point percussion system could not produce a very wide hole, and so the amount of water produced by the well was very limited.
The irrigation industry borrowed techniques from the oil industry. Since the mid-1800s, oil well drillers had been building large pyramid shaped derricks over a well site. Then a cutting bit with industrial diamonds imbedded in it was attached to a pipe, and the pipe and bit were rotated and forced down through the dirt and rock. The debris, or “cuttings,” were then forced back up the hole by water that was pumped down either the outside of the hole or the inside of the drill pipe. The walls of the well were stabilized by the introduction of a dense clay substance that penetrated the loose dirt on the side walls and hardened it.
Farmers who wanted to drill irrigation wells adapted the oil well technology to their needs. They didn’t need a huge semi-permanent derrick. Instead they needed a system that could drill an irrigation well fast and move to the next well site. They built a smaller derrick that would tip up from the bed of a truck. Then they added powerful new engines to drive the drill bits down.
Most well drillers in the Midwest, where water tables are relatively shallow, began using a technique called “reverse hydraulic” rotary drilling. The term hydraulic referred to the fact that they used water to pump the cuttings back up to the surface. A pond of water with clay in it was dug at the surface of the well. The water flowed down around the outside of the hollow drill stem and was then sucked back up to the surface by a pump attached to the drill stem. Gordon Schmidt says that reverse hydraulic drilling was “a very wet process.”
Gordon’s father-in-law, John Thieszen, built the first irrigation rig in York County, Nebraska, in the 1940s. It was built from a used truck, some new parts and stuff that they scavenged from the farm.
In York County, drillers had to go through 80 to 100 feet of soil and rock to reach a sand or gravel layer that usually contained water. They could tell when they reached sand by the motion and sound of the drill rig – sand is easier to drill through than the rock above it. Also they could look at what was in the cuttings as they came up.
When they reached the top of the sand layer, they kept going. In the 1940s and 50s, Gordon says, they figured that a hole another 60 feet lower in the sand layer would draw enough water for the well. Today, they dig irrigation wells as deep as the sand layer goes, sometimes another 110 or 120 feet below the top of the sand. They have to make sure they take advantage of all of the water potential in the well.
After reaching the bottom, all of that 200 feet of pipe would be hauled back up out of the well. Then, the first of many sections of perforated casing would be lowered into the well. This “screen” would allow the water to flow into the bottom of the well. When enough screen was attached, sections of solid casing would be added to the top of the well. Every sixth section of casing would have spacers attached to the outside to keep the casing centered in the well and plumb.
Finally, a carefully selected gravel mixture would be packed down around the outside of the casing. In the water layer, the gravel would filter out the finer particles of sand and keep the well water clean. In the rock layers, the gravel stabilized the casing.
Next the irrigator had to solve the problem of getting the water to the surface.