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Hole Driling for the Sensor Array
Designed by Mark Little
 
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Installing Sensor Array into the Ground

The installation of the sensor array into the ground requires a hole either 50cm or 100cm deep. Depending on the soil where the sensor pipe is going to be installed, it may either be necessary to dig a vertical hole using a post pole digger or shovel.

In some cases, it may be easier to use a stream of water from a hose to make a hydraulic drill.

How successful hydraulic drilling will be depends on a few things:

(1) The available water pressure. Without sufficient water pressure, it will not be able to excavate a hole deep enough;

(2)  The composition of the soil. If the soil has lots of rocks/rubble and/or is very tightly packed, the water may not be able to excavate a hole straight down and deep enough; and

(3) The ability to couple the high pressure water to the pipe so it can be efficiently delivered to the bottom where the soil needs to be displaced.

If you are unfamiliar with digging holes using water, then lots of information can be found on the Internet by searching for "digging a well using a garden hose". Of course, digging a 100cm is  not in the same league, but it will give you some idea of how it works.

Hydraulic Drilling

The following method only works properly for areas where the soil is greater the length of the pipe and does not have a lot of rocks and/or rubble. This is probably the case in domestic gardens. However, this not the case, then the use of a shovel may be required. It should be noted that after the hole has been dug, it will tend to collapse from the water in the hole, making it hard to re-insert the pipe into the ground as the hole dries out and slumps a bit. Ideally, one piece of pipe should be used to drill the hole, when a second piece holds the constructed and tested sensor array. Make sure that the connector is protected from dirt and water during the installation.

The first step in the process is find a nozzle for the hose that provides as as high a pressure as possible as it will be this pressure that blasts the dirt out of the way. Once the hose has been set up, identify the area where the sensor array will be installed.

Put the nozzle as close to the ground as possible before turning on the water flow. This will reduce the amount of water and dirt that start flying around. Once the hole been started, place the the nozzle on one end of the pipe and the other in the hole. Once the water is flowing again, work the pipe up and down, and rotate, to assist the water to drill down into the soil - and to help clear the soil from the hole.

The problem that you will have is that if you remove the pipe with all the water there, the hole may collapse and prevent the sensor pipe from being installed. If you leave the pipe in place and let it dry out, it may be difficult to remove when you wish to build and insert the temperature array.

Depending on your soil, it may be enough to just occasionally move the pipe that you used to drill the hole while the ground dries. Alternately, if you get two length of pipe, you can build the sensor array before you drill the hole and have it ready to replace the drill when the soil firms up a bit.