Mogotio Road Nairobi
Borehole Drilling Procedure
Geological/Hydrological Survey to be done by Registered Hydro-Geologist.
Getting Authorization from Water Resource Management Authority ( WRMA )
Conducting Environment Impact Assessment (EIA) & getting License 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 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 comes out clean. Generally it is 3 hours but still depends up on the hole.
Well head Slab: on the top 1mtr x 1 meter x 1 meter(LBH) digging pit & then making slab by using Cement, Send and gravel in proper ration which will prevent the hole by contamination. Sometime 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.
Obtaining Borehole number from the Ministry.