The shallow well type of technology is a very good and appropriate technology for providing safe and clean water to purely rural areas and communities and is cost effective. They can be evenly distributed in the water strained rural communities so that people especially women and children reduce on the walking distances they move to go and collect water.
Walking long distances to fetch water from far distant water sources in pushes brings about high risks of rape and defilement to the women and children. Many children also fail to go to school in time because they have to walk long distances to fetch water for house hold use and livestock i.e. chicken, cows, pigs, goats among others.
The shallow wells can easily be funded by NGOs as they can be phased out in small numbers for the construction and makes it possible to raise the money and implement projects in phases.
Method of Construction
Shallow wells are dug manually to depths of up to around 25 ft minimum and 35 ft maximum depending on the strength of the aquifer zones of the well and the yield and a diameter of about 1.5 metres.
The design of the well should follow the standards. The supervisor in consultation with the contractor during the digging process will confirm the type of well lining to be used depending on the stability of the soil formations encountered, most preferably porous cement blocks should be used.
Aquifer zones shall be completely lined with porous cement blocks. The blocks will be bounded together and tight enough to avoid openings which could lead to siltation of the well and they must be centralized in the hole. All wells should be vertical and all lining should be straight, round and plumb.
Backfilling: Suitable hard core should be supplied and applied by the contractor for the purpose of backfilling the hole especially when caving is encountered. The hard core (boulders) used should be irregular in shape, clean and from fresh rock.
Clay seal: Suitable to provide and effective seal to the entry of contaminants, the remaining annular space between the lining and the well wall will be laid with a well-prepared clay seal minimum 2 meters deep.
Cover Slab, Apron and Drain: After lining the well, a cover slab with an appropriate provision for the hand pump shall be placed and sealed on to the lining. A concrete apron 1 meter width shall be built as for the tube well platforms.
Cleaning and Disinfection of wells: In order to remove native silts and clay deposited on the well lining during construction, and to destroy pathogens that may be introduced in the well during the process, cleaning and disinfection of the wells shall be carried out by the contractor upon completion of the digging and lining of the well.
The cleaning shall involve the use of a hard abrasion brush. For disinfection purposes, a strong solution of chlorine in a bucket should be introduced in the well and mixing will be effected by re-circulation of the water using the dewatering pump. The well will be allowed to stay overnight to enable effective contact time to kill the bacteria.
Next day, the well will be pumped dry and the time taken to fill one ring or to fill a certain depth of lining will be an indication of the yield / recovery of the well.
Capping of well: After the well is constructed, the contractor shall use all reasonable measures to prevent entrance of foreign matter into the well as may be required or recommended by the supervisor.
Acceptance of the well: A well shall only be accepted by the supervisor upon satisfactory completion of all construction operations and well recovery monitoring.
Cleaning the site: On completion of each well, the site must be left clean and free from all debris with pits filled to the satisfaction of the supervisor.
- When the water holes for the shallow wells are dug to the depths of 25 ft. and beyond, there will be no problem of drying up but if the holes are lower than this depth, and if the yield the well is weak, there is a possibility that during the dry season, the facility might dry up.
- No shallow well facility should be constructed within a range of 30 meters radius of any existing latrine.