With the below documents at hand, one is now ready to drill a borehole. Drilling a borehole involves sinking a 8″ diameter hole to the recommended depth. The borehole is then installed with 6″ diameter casings to depth drilled and the annular between the borehole wall and the casings is filled with gravel packs. The borehole is then developed for about four hours depending on level of silt and backfill in the borehole.
A hydro-geological survey ought to be conducted on the client’s parcel of land by a registered hydro-geologist. This is done to ascertain depth recommended and also enables the drilling contractor as well as the client to understand the soil/rock formation of the intended drilling site.
This is issued to the client by the Water Resource Management Authority (WRMA) offices upon application and submission of the hydro-geological survey report. Geologist’s will often assist the client with this procedure upon request.
This is a requirement by the National Environmental Management Authority..
This applies when one wants to carry out drilling and related activities within major towns like Nairobi.
County governments also have their own requirements and will sometimes levy some fees for drilling activities.
The drilling process involves sinking a 8″ diameter hole to the depth recommended in the hydro-geological survey report. The hole is the lined with 6″ casings whereby approx 60% of the casings are usually plain casings and approx 40% are slotted casings that enable tapping of water at aquifer bearing zones. The annular of the borehole is then filled with gravel packs. Borehole development is thereafter carried out to clean the borehole of any silt and back-fill accumulated during the drilling exercise. Pump testing is then carried out to determine the yield of the borehole and a water sample is then taken to a government laboratory for Water Chemical Analysis. A bacteriology analysis can also be conducted at the client’s request.
A borehole is ready to be equipped with a pump after drilling and test pumping it to determine the yield. Our pump testing reports usually include a recommendation of the pump that is suitable for your borehole given the yield and depth. Pumps are of various types and we recommend depending on the power supply most available to the client. Shallow boreholes upto 90m depth in rural settings do well with hand pumps as they are most cost effective. Boreholes of up to 130m depth can work with solar pumps installations. We also have electric pumps or generator driven pumps.