The Four Stages Of Borehole Drilling and Construction In Zimbabwe!
Groundwater is undeniably a very important freshwater resource for drinking water supply, irrigation and industry, in addition to its natural role of sustaining river flow and aquatic ecosystems.
Sustainable groundwater development is fundamental in order to provide universal access to safe
drinking water. The lack of understanding of groundwater resources in much of Zimbabwe undermines
its potential to contribute to poverty reduction and economic development and threatens its
environmental sustainability.
Over the past two decades, Zimbabwe has witnessed a significant increase in Drilled Boreholes. These are financed by development programs as well as investments by water users and
local businesses. The use of groundwater in Zimbabwe is on the rise; the use of groundwater for irrigation in Zimbabwe is expected to grow significantly.
Boreholes are one of the best means of obtaining clean water in field conditions. However,
constructing, or repairing, boreholes requires specialized knowledge and technical expertise, much
of which can be gained from the standard literature; but field operations in remote areas or in
difficult conditions often require flexibility and imagination in avoiding and solving technical
problems.
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| The Four Stages Of Borehole Drilling and Construction In Zimbabwe! |
If boreholes are not properly sited, designed and constructed in the first place, supplies
cannot be maintained, and investments are wasted. And in the longer term, if groundwater
resources are not properly managed, there is the risk of over-abstraction and pollution and massive
failure of drinking water supplies. This cannot be allowed to happen.
Stage 1: Site Survey (Groundwater Investigations)
This is the first stage in the process of constructing a borehole. Depending on the geologist contracted to carry out the survey (Geophysical assessment), various techniques will be applied to sound (scan) the subsurface mainly to pick data from the site for technical analysis. This stage determines and answers the following questions:
a. Is there groundwater potential at the site.
b. Geological formation and setup of the area in question.
c. Recommended drilling depth required. This will influence the cost of drilling.
d. Likely challenges and possible solutions during the drilling exercise.
b. Geological formation and setup of the area in question.
c. Recommended drilling depth required. This will influence the cost of drilling.
d. Likely challenges and possible solutions during the drilling exercise.
Stage 2: Drilling and Casing
The drilling stage is the actual exploration exercise carried out using a rig operated on site. Borehole drilling is the process of punching a hole in the ground to extract groundwater. Everything that happens at this point is in reference and under the guidance of the surveyor’s report.The drilling exercise is usually completed by installing casings and well screens to keep the borehole from caving in yet allowing water to percolate into the well. This also prevents surface contamination, sand and other sediments from drawing into the well
After the drilling is completed, the drilling supervisor will provide a report with all the drilling logs mainly reporting on the following.
a. Total drilled depth.
b. Depth to the water strikes.
c. Driller’s estimated yield.
d. Well design and depth to screened water strikes etc.
If this stage is poorly handled, can lead to under pumping or total malfunctioning of the well. And worst-case scenario would be over pumping the well leading to a chain of problems like draining the well and eventually spoiling the submersible pump and its installed components. The aquifer test report will provide the following information that is later used to size a proper pump and power supply during the installation phase.
a. Static water level what some people prefer to term as the water table.
b. Dynamic water level
c. Safe abstraction or recommended pump installation depth.
d. Recommended pumping duration and rest interval to allow for recovery.
e. Discharge rate. This is the actual yield of the well-measured as m3/hr. (litres per hour) which is very crucial while sizing a pump.
After the drilling is completed, the drilling supervisor will provide a report with all the drilling logs mainly reporting on the following.
a. Total drilled depth.
b. Depth to the water strikes.
c. Driller’s estimated yield.
d. Well design and depth to screened water strikes etc.
Stage 3: Test Pumping.
Aquifer Tests also referred to as Test Pumping is done after the drilling exercise is completed. This is a scientific process that experiments with the performance of a borehole. This is done by pumping groundwater from a well, usually at a controlled rate and measuring the change in water level (drawdown) during and after pumping.If this stage is poorly handled, can lead to under pumping or total malfunctioning of the well. And worst-case scenario would be over pumping the well leading to a chain of problems like draining the well and eventually spoiling the submersible pump and its installed components. The aquifer test report will provide the following information that is later used to size a proper pump and power supply during the installation phase.
a. Static water level what some people prefer to term as the water table.
b. Dynamic water level
c. Safe abstraction or recommended pump installation depth.
d. Recommended pumping duration and rest interval to allow for recovery.
e. Discharge rate. This is the actual yield of the well-measured as m3/hr. (litres per hour) which is very crucial while sizing a pump.
Stage 4: Installations
Typically, what renders a borehole useful and complete is the installation of a submersible pump and all the accessories that come along. The most important information needed for a successful installation process is expected from the aquifer test (Test pumping) report. This includes the drawdown and rest water level, the safe abstraction or recommended pump installation depth, percentage of recovery versus recommended pumping duration time.This information helps to implement the right specifications for both the submersible pump and the capacity of the power source.
Conclusion: The stages as identified above can only be implemented one after the other. It would be a gamble to cost a single part of the process ahead without completion of the previous step. For example, you wouldn’t know the right size of the pump to install without knowledge of the actual discharge rate, and recovery rate of the well.
Conclusion: The stages as identified above can only be implemented one after the other. It would be a gamble to cost a single part of the process ahead without completion of the previous step. For example, you wouldn’t know the right size of the pump to install without knowledge of the actual discharge rate, and recovery rate of the well.
PROWATER SYSTEMS ZIMBABWE
Standard Prices For Borehole Drilling
Borehole Siting (Geo-Survey)
$80 USD
Get Quote
Drilling & Casing (40m)
Standard Class 6 Casing included.
$1,000 USDGet Quote
Premium Casing Upgrade
Upgrade to Class 9 Casing for extra durability.
Add $250 USDGet Quote
Borehole Deepening / Extra Metres
For drilling beyond 40 metres.
$30 USD / mGet Quote
Double Casing
For unstable ground conditions.
$20 USD / mGet Quote
Tank & Tank Stand
5000 Litre Tank with a 4-metre Stand.
$1,000 USDGet Quote
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