We have taken the time to compile the information that you will need to put your mind at rest before you make an informed decision. There are four steps involved between the moment you decide to invest in a domestic borehole, and getting water pumped out of the earth. We thought it beneficial for our clients to understand the steps involved, so we outlined the four steps below..
Before borehole drilling there is need to conduct a Hydro-geological Survey in the proposed site. Generally groundwater is unequally distributed surveys ascertains suitable sites for exploration of significant quantities of groundwater before carrying out any drilling exercise.
This ensures the best spot is selected according to the geological data and our clients’ plan. The hydro-geological data, maps, graphs and cross-section profiles obtained from the hydro-geological survey are used in determination of important information such as estimation of drilling depth and Identification of stress areas
Site Mobilization consists of preparatory work and operations necessary for the movement of
personnel, equipment, supplies, and incidentals to the project site.
Mobilization includes the transferring to the job-sites of all equipment, plants, supplies and materials, personnel, and all items necessary for the execution and completion of the work, and shall also include the setting up of all equipment, instruments and all other plants until rendered operable, subject to the confirmation of the Engineer.
It is only when the rig is complete set up that the workers can begin the operations for the drilling itself. It all begins in the starter hole where a surface hole is drilled down to a specific measurement. Afterwards, the stages of drilling are continued.
Rotary using the mud flush technique (Mud drilling)
Here, a drill bit made from tough materials is attached to the end of a drill pipe. When the process is started, the driller waits until the bit is moving across the substrata. Once it has been confirmed, some drill fluids are passed through the drill pipe, into the hole and then back to the surface. This process is very important as it washes the residue and cuttings back to the surfaces. The fluid has many purposes including the fact that it gives lubrication for the drill bit.
Rotary with air percussion and flush (Air Drilling)
This method makes use of compressed air to help break up hard rock formations. This borehole drilling mode requires the skills of an expert. The compressed air is usually used to operate an air hammer which is situated deep down the hole. The same air is what will eventually blow the crushed fragments as well as water up the hole that is being created.
The collection of representative subsurface samples is key to the development of relevant and accurate geotechnical evaluations and assessments. As the drilling process continuous, geological rock samples are taken at set intervals. Struck and water rest levels are constantly recorded. This process enables us to estimate the yield of individual aquifers encountered.
The cassing process keeps the well open and protects the earth, similar to the efforts to protect groundwater. The hard metal cassing shores up the borehole and extends through both the verticality and the horizontal drilling phases, assuring the long-term integrity of the well from end-to-end. In addition to providing stabilization and keeping the sides of the well from caving in on themselves, cassing protects the well stream.
Developing a well is the process of removing fine soil particles, drill cuttings, and residual drilling mud from the well screen and borehole annulus in order to establish a good hydraulic connection with the surrounding formation. This development aims at repairing the damage done to the aquifer during the course of drilling by removing additives from the borehole.
The final stage of borehole drilling requires the pumping and piping of water from the successful borehole. The end use of the water will largely determine the type of pumping and reticulation system that will be installed. With too many variations on the nature and type of pump installations to go into detail here, we will discuss the most appropriate options with you in person. Contact Export Hydro to learn more about this processtowards investing in your own borehole.
Test Pumping involves pumping of a well from a measured static water level at a known yield, and recording the rate and pattern by which the water level within the well changes. Once a dynamic water level is reached, rate of inflow to the well equals the rate of pumping. Towards the end of the test a water sample is collected for chemical analysis.
The duration of the test is 24 hours, with a further 8 hours for a recovery test. The results of the test enables the hydro geologist to calculate the best pumping rate, the installation depth, and the drawdown for a given discharge rate.
