Kisima Drilling (E.A) LTD
Borehole Drilling Procedure
- Formalities :
- Geological/Hydrological Survey to be done by Registered Geologist.
- Getting Authorization from Water Resource Management Authority ( WRMA )
- Conducting Enviornment Impact Assessment ( EIA ) & getting Licence from NEMA.
- Getting No Objection Letter from Water Service Provider like Nairobi Water Company, Mavoko County Council etc.
- Actual Drilling Process :
- Drilling of 11”until loose top formation & installing 9” temporary casing then Drilling 8” up to recommended depth.
- Casing : Installation of 6” Casing pipe – Class – B ( 4.5mm thickness ) up to bottom . Generally ratio of Plain Casing & Screen casing is 70 : 30. but depends up on the hole drilled.
- Gravel Pack : Inserting 2-4mm natural gravel outside the casing and inside the open hole for artificial filtration.
- Development : one need to do development by air jetting until water come out clean. Generally it is 3 hours but still depends up on the hole.
- Well head Slab : on the top 1mtr x 1 mtr x 1 mtr ( LBH) digging pit & then making slab by using Cement, Send and gravel in proper ration which will prevent the hole by contamination. Some time client like to have a manhole which will be under ground with metal cover , so that place will look like flat .
- Capping : fitting cap on the top until installation of pump etc.
- Test Pumping : For the measuring exact yield of the borehole one has to do test pumping i.e. pump out water continuously 24 hours , then one can know the yield of the well and the rest level & pumping water level etc. This is most important process to decide the size of pump.
- Water Chemical & Bacteriological analysis by government chemist to know the water is suitable for the domestic / industrial use or not .
- Completion Report : preparing completion report ( Form 009 A ) as per WRMA rules & submit to the WRMA office as well as to the client.
- Installation of Pump :
On the basis of test pump report one can decide the Pump Installation depth , and size of pump , motor, delivery pipe, cable , control panel, water meter and
other sundries.