Wednesday, July 15, 2015

Why do boreholes collapse in Lagos

Borehole failure can be described as the instability of subsurface strata due to inadequate compaction and inability of the bored well to perform up to its installed capacities.
This is due to
1 Low quantity of cement materials (clay) and inadequate compaction
2 High hydraulic conductivity of the concerned  loose layer
3 Vibration of the ground from adjacent vibrating source.
4 Excessive withdrawal from adjacent well.
5 Wrong screening of the pipe and use fake water pump etc
NOTE: This is also applicable to basement complex areas like Ibadan , Ilorin, Akure, Ondo etc

Why do you need geophysical survey before drilling a borehole

Although one can come across water at any depth in a sedimentary environment like Lagos (the reason for so many “successful” shabbily executed shallow holes in Lagos) however there is more to borehole drilling and construction than just locating the depth to water table.
Geophysical exploration helps in locating region of abnormal water potential (high hydraulic conductivities) hence give information about the subsurface region that is prone to possible collapse. It helps to demarcate fresh water and salt water boundary especially in places close to the coastal region of Lagos (Lekki and environ). It particularly differentiates between regional water table (main aquifer) from perched or local water level which are usually polluted and inadequate for prolong use. Etc


SUGGESTED SOLUTIONS
1. Contact, consult and/or contract only experts in the field from project conception to execution. 
2. Have a clear and deep understanding of the geology of the area (your site) before developing a site plan or erecting permanent structures (ensure your soak away is not sited on the best and only aquifer with your site or neighbourhood).
3. Carry out detailed geophysical appraisal of the proposed site to reduce future wastages and ensure   engineering and architectural best practices. 
4. Use well formulated drilling mud during construction of borehole to prevent failure.
5. Insist on having a project report with drillers/well log for convenient and smart borehole maintenance.
6. Beware of quack Doodle buggers or ensure you have a maintenance commitment/agreement if you must use one.

For excellent geotechnical, geophysical and other geoscientific services at rock bottom prices by seasoned professionals contact:

Eris Akpe

Eris.akpe@gmail.com
08130942347

Or 

made@madeonlineng.com

No comments: