With over 170 million population, less than 25 percent Nigerians are able to access portable water and as such majority of people have resolved to drilling boreholes in their houses as a means of accessing potable water. Sometimes, this is done indiscriminately, without considering the health implications.
T. R. Ajayi, Professor of Geologist, Obafemi Awolowo University, Ile-Ife said if a borehole is too close to a soakaway there must be a leakage. He noted that there must be a minimum distance away from the soakaway. He insists that the quality of materials used must be top notch to avoid contamination which can lead to loss of life.
“If the soil is sandy the only thing to do is that you go deeper and blind all the upper area, from the top soil to the rock. You must avoid the possibility of any leakage to your borehole, you must bind it thoroughly so that there are no perforations.”
“There’s what we call water table and it depends on where you are, if it’s dry season your water table is very low and if it’s raining season your water table will be high. Depending on your used material, borehole erection varies from place to place.” Ajayi states.
Ajayi further adds that it is important to give 10 metres away when putting up a borehole however, it is crucial that you meet with the ministry of environment or a geologist to tell you the nature of the environment before you can site your bole hole.
According to John Owo, C. E.O Cooha Water Technologist Limited, “National Agency for Food Drugs Administration control (NAFDAC) standard requires 10 metres that is 33 feet away from the septic tank and also the civil engineers have said the same thing. Sometimes the situation can change in an instance where we have a cavity due to issues in the ground where there is a mixture of the water from the soakaway trying to penetrate the bore hole.”
“If there is no space of 10 metres you can at least give up to 7 to 8 metres, and if there’s a space at the back of your building depending on the side your engineer wants to site the bore hole, use 4 square or 10 by 5 or it can probably be 15 by 5 that is in a straight form, depending on where the space is.” Owo adds.
For Oretayo Oni, a medical practitioner in Lagos, “Borehole water contains microbes that can cause ill health. It may also contain chemicals such as Calcium, magnesium and so on. These elements are not bad in themselves but when consumed in large amounts can predispose to stone formation.”
Soakaway construction is a low environmental impact solution to drainage because it is uses few materials. As this drainage system deals with the surface water in the area where it is occurring, you are avoiding the need for processing or adding to the overburdened council drainage and sewerage systems. It also avoids the need for chemical treatments before being returned into the eco system. The surface water is less likely to become polluted before it returns to the ground.
A borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water, other liquids (such as petroleum) or gases (such as natural gas), as part of a geotechnical investigation, environmental site assessment, mineral exploration, temperature measurement, as a pilot hole for installing piers or underground utilities, for geothermal installations, or for underground storage of unwanted substances, e.g. in Carbon capture and storage.
Drilling has over the years developed to a highly specialized and technical activity. Drilling with jumper rigs as in the olden days rarely takes place and most of the boreholes drilled are drilled with the air percussion technique. This technique is fast and efficient. However, when drilling a borehole for groundwater abstraction purposes, drilling becomes much more than just making a hole in the ground.
Drillers may sink a borehole using a drilling rig or a hand-operated rig. The machinery and techniques to advance a borehole vary considerably according to manufacturer, geological conditions, and the intended purpose. For offshore drilling floating units or platforms supported by the seafloor are used for the drilling rig.
Typically, a borehole used as a water well is completed by installing a vertical pipe (casing) and well screen to keep the borehole from caving. This also helps prevent surface contaminants from entering the borehole and protects any installed pump from drawing in sand and sediment. Oil and natural gas wells are completed in a similar, albeit usually more complex, manner.
TIAMIYU ADIO
