Tanzania

Engare project

By Novembre 9, 2019 No Comments

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Here is the Report on the hydrogeological and geo-electrical survey for selection of the potential site for borehole drilling for water supply to Nadosoito Village Terati area 
in Simanjiro District, Manyara region – Tanzania.

The company has done a boreholes investigation fore borehole drilling for water supply to the village. To have water, the women of the village have to go to a place one hour far each way to collet dirty water.
Pumping test: A test that is conducted to determine Aquifer or well characteristics.
Aquifer: A geological formation or saturated which store and transmit water and which may supply water to wells, boreholes or springs.
Fault: a fracture or a zone of fracture along which there has been displacement of the sides relative to one another parallel to the fracture.
Recharge: The general term indicating the process of transport of water from surface sources (i.e. from rivers or rainfall) to the groundwater.

At the present there is no any source of water supply to the area.

Simanjiro - north of Tanzania

Engare project

For Tanzanian women

LOCATION OF THE SURVEYED AREA:
Nadosoito village is located some 65 kilometres south of Arusha City centre, off Arusha – Custom main road. T
he investigated are
a is approximately bounded by Latitudes 3o341′ and 3o36′ South and longitudes 36o25′ and 36o27′ East.

The surveyed area is occupied by granites and gneissic granites, calcareous limestone overlain by red siliceous soils and black clay soils. The granites and gneissic granites are highly fractured/weathered and fissured. The fractured /fissured and weathered granites and gneissic granites are potential aquifers at the area surveyed. This has been revealed by a productive borehole at the south of the area.

Generally speaking, the groundwater quality at the surveyed area is expected to be good since the existing groundwater sources from boreholes drilled in the vicinity of the surveyed area, have good quality water except fluoride concentration in some places.

A great variety of geophysical methods are available to assist in the assessment of geological sub-surface conditions. In the present survey the resistivity (Vertical Electrical Sounding) and Magnetic Profile method have been used.

CONCLUSIONS AND RECOMMENDATIONS:

a) Geological, hydrogeological, geomorphological, climatological (heavy rainfall at the surveyed area, resulting to groundwater recharge) condition, as well as the results of the resistivity sounding which has thick overburden underlain by thick layers of fractured/weathered basaltic rocks, favour the occurrence of groundwater.

b) Direct mud rotary or percussion method of drilling is recommended right from the start to avoid caving in of the unconsolidated sediments during the drilling operation.

Suitable sites have been located by means of geo-electrical field measurements, (Magnetic Profile and Vertical Electrical Soundings) where the rock is found to be fractured to greater depth (estimated 30 – 140 metres below ground level). The quantity and quality of groundwater at the site selected for drilling is expected to be good.

A pilot hole of should be drilled to the recommended depth, reaming will be done after proving the water

Application of the drilling permit according to Water Resources Management ACT WRM no 11 of 2009 is recommended.

c) The recommended depth and well assembly for the borehole to be drilled are 140 metres, and 15.24 cm respectively. The borehole diameter is recommended to be 20.32 cm.
However, the final drilling depth can be altered by site supervisor depending on the rock strata penetrated, quality and quantity of water struck during the drilling operation.

d)  Drilling of the borehole, design and installation of well assembly and pumping test should be carried out under supervision of a Hydrogeologist/senior Technician

e)  Large, clean, well rounded quartz pea-size gravels (2 – 4mm diameter) should be used in packing the borehole.

f)  Water from different strikes/aquifers should be chemically analysed for quality at the Water Quality laboratory.

g)  A concrete slab should be built around the top of the well assembly for sanitary
Protection. The top five (0 – 10) metres should be cement grouted to avoid Pollution.

h) After construction the borehole should be fully developed by compressed air until the water becomes absolutely silt free before a production testing of at least 6 hours.

i) The recommended drilling site was marked by a wooden peg and is known to: Village chairman Isaya 0764377777 and Mh Michael Haiyo 0739169430

 

Marin  Salala
HYDROGEOLOGY  UNIT
AL – AMRY DRILLING  COMPANY