Introduction to water wells

Assisting a group of engineering students led to this water well introduction. Here we start with the well seal, sand and gravel.

Okay. Sanitation is first, actually. Maintain significant distance between toilets and drinking water. Dig for water in places safe from flooding and away from sewage.

Well casing is a pipe put in a hole drilled into Earth. Perforations in the well casing allow water to enter the well casing when pumping. More holes let in more water. And big holes let in more water.

An open hole refers to a water well that has no well casing. This is possible in stable geologic formations that do not erode. It is an unusual occurrence.

Another unusual geologic formation is a water source that includes fine sand that flows with the water. Fine sand requires many small perforations or contiguous slots. The size of the perforations excludes large grain sand placed around the well casing. A more typical well packing is gravel.

Water well sand packing around the well casing has interstices between the sand particles that catch the larger grains of native sand. Fine sand geology is as rare as the geology that supports an open hole. There is a three way relation between; 1. water yielding strata (geology), 2. the sand or gravel particle size installed around the well casing, 3. the size of the water well casing perforations.

New water well. Install pump. Run the pump until water is clear and without sand.

drawing of water well

A small crane can be made of 5 cm water pipe (2") that fits into a 6 cm or larger stand pipe (2.5"). This small derrick has been sufficient for small pumps and 3 Meter lengths of pipe. at 30 - 40 Meters of depth ± (95'). It is easy to move from one water well to another. Each water well requires a derrick mounting pipe, as illustrated.

The upper part holds the pulley. It is partly made of 6 cm pipe that fits over the vertical pipe. This crane requires very little fabrication effort. It provides independence from expensive machinery for minor water well maintenance. The top of the derrick is 3.7 M ± above the top of the well casing (13').

The total length of derrick pipe needed for sufficient work space for the pulley and all parts is 6 Meters (19.7'). Use a full length of pipe and cut it shorter with experience.

A strong man can stand up a 6 Meter (20 ft) length of 5 cm (2") pipe. Use a stable 3 Meter ladder (10'). Warning! Cinch the ladder with tight wires to do this. Two people working together can raise the 6 Meter pipe quite easily.

drawing of small derrick and well

The hand crank has a ratchet mechanism. The handle does not spin free if a person makes a mistake. Dropping the pump or tools into a well begins what is known as a fishing expedition. One must go through a sometimes heroic effort to retrieve the object that fell into the artesian well.

A falling pump presents added danger from the electric line and the rope attached to it. A person can be injured. Do not try to stop a rapidly falling object! Maintain personal safety.

Back to the job

The lifting loop: it is made to thread into the female connector at the top of each pipe section. The hook is inserted into the bale loop to lift or lower the pump. This is a necessary tool. It is easy to make. Weld a loop of steel to a short pipe. Similar to the drawing below. Use ordinary steel pipe. Black steel is best. The bale fits the pipe connector of the pipe in the well. Shown sitting on the support. (slip = ) be careful.

A swivel hook is best. If there is no swivel, turn the suspended pipe joint backward a few turns before connecting (during installation).

drawing of bale

All the weight is held by the pipe connector. The connector is larger than the slot. Tie a saftey rope to the crane pole when the hook is temporarily disconnected. Small bumps on both sides of the U shaped slot will help keep the pipe in place.

Some well-head tools have safety chains that hold the pipe firmly in position. Much thought has been devoted to safety clamps for well pipe support because pumps have fallen into the water well. A short length of rope around the pipe under the slip and then over the slip will help hold the drop pipe in the slip yet still leave room while using wrenches to work with pipe and joints, some people also attach small safety ropes to the wrenches.

drawing of slip

Threaded connectors are commonly used with steel or heavy wall plastic pipe. If plastic pipe is glued, put a few small screws through the glue joint. The slip functions the same with threaded pipe and connectors or if threaded male and female connectors are glued to the pipe. Allow glue to cure for several hours before setting pump. Be wary that a threaded pipe may break where it enters the connector, if the pipe is bent with too much force. A strong crew can do this during a struggle to lift a pump without a crane. Secure the safety line before working with threaded joints of any type.

Water well quantity test

drawing of well test

Many pump controllers automatically turn the pump off when it sucks in air. A sensor registers a reduction of amperage draw when the load decreases because of air rather than water in the pump. Be sure your pump controller includes this or some other way to turn off the pump when there is insufficient water. A dormancy time can be set for pumps installed in low yield wells. This restarts the pump after the water source has refilled the well casing.

Geological Water Search

drawing of geological strata

The solid horizontal line represents the starting direction of a horizontal well bore hole. The associated broken line indicates a probable path due to gravity. The vertical well direction tends to move downhill with gravity, also. The oval represents an exposed cliffside that shows a peach-like blush of moisture during the rainy season. The small broken line represents a road from which one might have seen the subtle damp oval. Perhaps living nearby for years before realization of the full meaning.

Imagine standing on this mountain with even larger mountains and a continent to the left. Subterranean water will flow from the lower left to the lower right. And then up and back toward upper left. This happens because water flowing from lower left is continental. The subterranean water encounters an impermeable strata and is blocked until it finds a route to the sea.

Gravity pulls subterranean water downward and to the sea; if that direction is blocked, pressure from higher mountains will push it upward as high as distant continental mountains. Up-and-down and side-to-side, zig-zag routes can happen many times as continental water travels to the sea.

In this drawing, seasonal water from local rain flows from upper left toward lower right. Occasionally, subterranean water will encounter an impermeable layer and appear as running water on the surface (not a good strata for a water well). If one sees the blush of moisture on a rock cliff, as illustrated by the oval, this is a good strata for a water well.

Vertical and horizontal wells in the same strata will yield a similar amount of continental water during a dry summer; this happens when the vertical well is artesian because the water originates from higher mountains.

The point here is that looking for water can be successful with simple observation.