USAID ETHIOPIA...Verification and Findings of Each Project area 2.1.Gult 2.1.1. Location Gult is...
Transcript of USAID ETHIOPIA...Verification and Findings of Each Project area 2.1.Gult 2.1.1. Location Gult is...
Ethiopia Health Infrastructure Program (EHIP)
Health Centers Groundwater Investigation Supplementary Report October 2017
This publication was produced for review by the United States Agency for
International Development. It was prepared by Tetra Tech, Inc.
USAID ETHIOPIA FROM THE AMERICAN PEOPLE HEALTH INFRASTRUCTURE PROGRAM
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Contents
I. Introduction ................................................................................................................................... 3
1.1. Objectives of revisiting of sites ............................................................................................... 4
1.2. Approach and Methodology of the study .............................................................................. 5
1.2.1. Field investigation ............................................................................................................ 5
1.2.2. Desk study........................................................................................................................ 8
Part II. Verification and Findings of Each Project area ...................................................................... 9
2.1. Gult ......................................................................................................................................... 9
2.1.1. Location .......................................................................................................................... 9
2.1.2. Physiographical set up of Gult ....................................................................................... 9
2.1.3. Existing Water Supply ................................................................................................. 10
2.1.4. Geology and Hydrogeology of Gult area...................................................................... 11
2.1.5. Geophysical Survey ...................................................................................................... 16
2.1.6. Environmental aspects for the off-site of Gult health center ...................................... 18
2.1.7. Conclusion and Recommendations .............................................................................. 19
2.2. Maksegnit ............................................................................................................................. 22
2.2.1. Location ........................................................................................................................ 22
2.2.2. Physiographical set up of Maksegnit area. .................................................................. 22
2.2.3. Existing Water Supply .................................................................................................... 23
2.2.4. Geology and Hydrogeology ............................................................................................ 23
2.2.5. Geophysical Investigation............................................................................................. 27
2.2.6. Conclusion and Recommendations .............................................................................. 29
2.3. Gulem Dengin....................................................................................................................... 31
2.3.1. Location ........................................................................................................................ 31
2.3.2. Physiographical set up of Gulem Dengin area ............................................................. 31
2.3.3. Existing Water Supply ................................................................................................. 32
2.3.4. Geology and Hydrogeology .......................................................................................... 32
2.3.5. Geophysical Investigation............................................................................................. 34
2.3.6. Conclusion and Recommendations .............................................................................. 37
2.4. Gerbicho ............................................................................................................................... 38
2.4.1. Location ........................................................................................................................ 38
2.4.2. Physiographical Set up of Gerbicho ............................................................................. 38
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2.4.3. Existing Water Supply ................................................................................................. 39
2.4.4. Geology and Hydrogeolgy ............................................................................................ 39
2.4.5. Geophysical Investigation............................................................................................. 40
2.4.6. Conclusion Recommendations ........................................................................................ 42
III. Schematic Design, Delivery system and Power Generating system ........................................ 44
3.1. Schematic Design of Gult extracted from Google Earth .......................................................... 44
3.2. Water Well Design ............................................................................................................... 47
3.3. Proposition of Estimated Bill of Quantity for Boreholes ......................................................... 52
3.4. Propostion of Bill of Quantity for Solar PV and Pipe lines ................................................. 57
List of Figures
Figure 1. Discussion on Field Visit .......................................................................................................... 7Figure 2. Geophysical Investigation ......................................................................................................... 8Figure 3. Get to Gult Health Center ......................................................................................................... 9Figure 4. Hand Dug well site of Gult ..................................................................................................... 11Figure 5. Massive Basalt along the perennial river east of Gult Health Center ....................................... 12Figure 6; Geological map of Gult area. .................................................................................................. 14Figure 7. Hydrogeological Map of Gult area .......................................................................................... 15Figure 8. Gate to Maksegnit Health Center ............................................................................................ 22Figure 9. Geological Map of Maksegnit ................................................................................................. 25Figure 10. Hydrogeological Map of Maksegnit ...................................................................................... 26Figure 11. Get to Gulem Dengin ............................................................................................................ 31Figure 12. Geological Map of Gulem Dengin area ................................................................................. 33Figure 13. Hydrogeological map of Gulem Dengin area......................................................................... 34Figure 14. Geological Map of Gerbicho area.......................................................................................... 39Figure 15. Hydrogeological map of Gerbicho area ................................................................................. 40
List of Tables
Table 1. Geophysical Interpretation Result of Gult area ......................................................................... 17Table 2. Interpretation Result of VES in Maksegnit Health Center ........................................................ 29Table 3. Interpretation result of Gulem Dengin ...................................................................................... 36Table 4. VES interpretation result of Gerbicho ....................................................................................... 42
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I. Introduction
This report is an ancillary study document prepared by Shumet Kebede water Works
Consultant to TETRATECH/USAID, concerned on the possibilities of relocating the sitting of
wells inside the four named health centers compound than the previous proposed sites. The
report deals on Physiographical set up of the area, Geological, Hydrogeological, Water supply
schematic design and recommendations about the revisited four sites.
It is to everybody’s knowledge that the preceding study document has proposed the water supply
options of the 17 health centers constructed by USAID in Amhara National Regional State and
SNNPRS regions. As has been portrayed in the technical details of the previous Technical
Report, the scheme type proposed for most of the health centers is drilling of shallow to medium
depth boreholes, in most cases, inside the premises of the health centers. However, in some of
the health center sites, the well sites are located outside the compound of the health centers when
the health center compounds are identified to be poorly responsive to hydro-geological
parameters.
Of these sites, Maksegnit, Gult, and Gulem Denjin health centers in Amhara region and another
site named as Gerbicho in SNNPRS are revisited and studied again to relocate the sites and for
possible drilling options inside the health center compounds with an anticipated minimum daily
water demand of 5M3 per day, which is even less than 0.5 lit/sec.
Except Gult site left unchanged, the rest three well sites are shifted to the health center
compounds with adjustments on the depth of the wells with an anticipated minimum daily
abstraction of 5m3/day, as has been suggested by Tetra Tech/USAID.
The relocation of sites was conducted jointly by staffs from Tetra Tech and the consultant,
shumet kebede water works. The team members for the revision of the sitting of wells are: Mr.
Tom Keefe and Mr. Samson Kifle from Tetra Tech and Mr. Shumet Kebede and Mr. Nuru
Mohammed (Hydrogeologist and Geophysicist) from the consultant.
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The first round site visit was conducted from September 3, 2017 to September 7, 2017 in
Maksegnit, Gult, and Gulem Denjin health centers in Amhara National Regional State whilst the
second round was performed from September 13, 2017 to September 15, 2017 in Gerbicho site
in South Nation Nationality Peoples Regional State, after celebration of the New Year Ethiopian.
The field site was done separately from the consultant team to respect conveniences.
The Report consist of mainly three parts
Objectives of the present study, Approach and Methodology of the study for all sites
Verifications and Findings for each Investigated site
Schematic Design, Delivery system and Power Generating system
1.1. Objectives of revisiting of sites
The principal objective of the study was:-
The objective of this contract is to identify borehole sites and provide schematic design
for the most feasible and cost-effective means of supplying water to the four health
centers.
The specific objectives includes (but not limited to):
Verification of previously studied sites and Groundwater assessment
To identify and propose appropriate scheme types and sitting of wells
Proposition of schematic design for off-site sources
Preliminary Recommendation of Pumping system
Preliminary Engineering estimates of drilling cost and construction cost
• • • • •
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1.2. Approach and Methodology of the study The methodologies adopted and applied in the project areas are widely accepted standards and
definitely improves the success rates significantly. The work at this stage consists of: Field Visits
and Desk Study. The Field Visit was the first approch performed for these four Health Centers,
for the reason that most of the works has be done by the same consultant. However, the previous
report was revised thoroughly.
1.2.1. Field investigationThe field investigation works were conducted from September 3 to September 7, 2017, in three
Health Centers, namely, Gult, Maksgnit and Gulen Dendin in Amhara National Regional State.
And then the second field visits performed from September 13 to September 15, 2017 at
Gerbicho Health Center in South Nation Nationality Peoples Regional State. The field works was
interesting that have been supported by a detail all rounded professional discussion and have
attained mutual understanding of the groundwater conditions at all revisited sites.
The major activities covered by the field work include:
Reaching to the project areas and visit previously selected borehole and spring sites
Brief explanation on the previously selected sites in terms of Physiographical, Geological
and Hydrogeological viability.
Transect walk in conformity along the inferred geological structures and drilled
boreholes, considering the remote sensing data interpretations and other relevant
documents analyzed at the first task.
Detailed assessment of structural and Geological setup of target areas and their relation
with Geological structures and Hydro-geological importance.
Evaluation of recharge and discharge conditions /catchment area and hydrometeorology/,
Evaluation of available drilled boreholes.
Geophysical investigations in the compound of Health Centers for feasible
Hydrogeological condtions and outside for non-feasible hydrogeological areas in the
compound of Health Centers
Discussion with relevant professionals and project coordinators
Selection of Borehole site based on the overall investigation and detail discussion with
the team.
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Collection of water samples and conduct in situ measurements
The most important equipments used include.
Earth Resistivity Meter (PASI, Brand New digital resistivity meter made in Italy)
pH and TDS meter
EC meter
Lap top computer
High resolution GPS (The UTM coordinates, i.e. Easting and Northing, obtained with the
help of a GARMIN II GPS receiver in Adindan datum and then transferred to WGS Datum)
Thematic Mapper satellite images and DEM(Digital Elevation Model 30X30m
resolution)
Digital Topographic Maps(1:50000) and Hydro-geological map of Ethiopia (1:50000)
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Figure 1. Discussion on Field Visit
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Figure 2. Geophysical Investigation
1.2.2. Desk study
Water Resources investigation at this phase started through examining the previous Groundwater
Investigation report. And then after field visits detail interpretation made Usage of Shuttle Radar
Terrain Mission (SRTM) data generating for Digital Elevation Model (DEM) with 30 * 30
meters resolution and identify regional structures and drainage patterns. After detail discussion
with Tetra Tech higher Experts and His Excellencies Mr. Tim Michael, water delivery rout
suggested. Finally this Technical Draft Report produced.
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Part II. Verification and Findings of Each Project area
2.1. Gult
2.1.1. Location
Gult is located in Amhara National Regional State in south Gonder Andabet Woreda. It can be
reached to the site through Jara Gedo Town, Which is third grade asphalt road to Jara Gedo town
and then 10 km to west through all weathered gravel road and 6 Kilometres along only dry
weathered road. The health centre is under construction and close to the final stage.
Figure 3. Get to Gult Health Center
2.1.2. Physiographical set up of Gult
Physiography is the physical characteristics of an area, which includes Topography, Drainage,
Vegetation cover, Soil type etc. The study of Physiographic features and identification of
geological structures and drainage patterns is done by interpretation of Enhanced Thematic
Mapper satellite images at a resolution of 30*30 meters. In order to confirm the observed SRTM
observation has been confirmed by Geo traverse.
Gult, is part of the North-western Highlands of Ethiopia, aligned in Guna mountains catchment
GULT HEALTH CENTER ,.,.......,_,,_.,,.,._., .......... _., -... ....... USAIDo,_...._ ... .,_..,,ltt,yo,-
7-A-), /..'i "NI.,
.&u 111.'S' "IA.,r l.\14Sta .... I: :,f: '11-t,tt ,-,,- • • t: +1-t:A .2-CJ!+ lr""f fl'I_,. -..u .. c :,c 1•• 41C +lltit•
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which has a peak altitude of 4120masl. The Health Center is located at a local water divide,
where either side is drained by intermittent streams. The intermittent stream has base flow for not
more than a month after the offset of the rainy season. The streams emerge at the foot of water
dividing hills fed by small catchment areas and generally drain to the Blue Nile basin located a
few kilometers away from Gult Village.
The area receives precipitation from its uni-modal rainfall pattern annually from June to
September. Gult is classified as humid sub tropical / weina Dega / based on the Ethiopian Agro-
climatic zoning. The mean annual temperature is 14-18 0C and the mean annual rainfall is 1000-
1200mm annually
Development of soil is very poor in the area; the thickness varies very few centimeters close to
the hill and very few meters downstream of the village. The prominent soil type is reddish
brown. The vegetations covet also poor except along the river.
2.1.3. Existing Water Supply
For village water supply the peoples are getting water from Excavated hand dug well. There are
three hand dug wells excavated along the Perennial River close to each other, however one of
them is not functional. Location of the hand dug well has a walking distance of 10 to 15 minutes,
therefore most of the community are getting water from unprotected perennial river, during wet
seasons peoples are preferring to fetch water from small seepages emanating at the banks of river
and stream to minimize their walking distance.
In order to supply potable and clean water the Regional Water Well Drilling Enterprise, which is
a governmental owned enterprise drilled two shallow wells along the perennial and seasonal
stream, but the wells are dry and abounded. The study team has evaluated positions of drilled
wells and has got locations of pinpointed sites has been found wrongly sited. Details are
elaborated in Geological and Hydrogeological part of this report.
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Figure 4. Hand Dug well site of Gult
2.1.4. Geology and Hydrogeology of Gult area
The regional Geological and Hydrogeological set up of the area is explained in the previous
study document. Hence, this report deals mainly on the local Geology and Hydrogeology of the
study area. The study team made geo traverse to understand the local geology along rock
exposures, seasonal streams and perennial rivers, besides its map based studies.
The rock exposure along the seasonal stream exhibits colluvial deposits and aphyric compact
basalt that covers the whole river bed extending to the cliff. See Fig 5, below
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Figure 5. Massive Basalt along the perennial river east of Gult Health Center
As it can be observed in the above picture, the exposed rock along the seasonal river bank is
massive and doesn’t exhibit cracks and fractures that can facilitate groundwater percolation. The
geological feature along the stream is characterized by massive alkaline to transitional basalt and
comprising small catchment area close to the hill.
Gult village is located on a hilltop and a local water divide bounded by two opposite lying
hanging valleys to the north and the south of the health center.
The south lying valley starts at the foot of the nearby hill and covers small catchment area. The
area is highly degraded and the intermittent stream is flowing over the basaltic layers (as shown
in the above figure). The rock units exposed on this part of the valley are fresh and massive in
nature. The joint density of the basaltic rock is minimal that favors runoff than infiltration of
water. Besides to these the poor hydrogeological situation of the area has been proven by the
well drilled in the area at a position of37P + 373434E and 1257252N along this stream, which
was drilled by Amhara water well drilling Enterprise to a depth of 60 m was dry. The study team
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surveyed the abandoned well site and has understood the site is wrongly selected without detail
and scientific step by step methodological procedures.
Hence, this part of the catchment is concluded as not feasible for drilling of wells from
Hydrogeological point of view.
The other side of the village, the North West catchment, drained by a perennial river with little
base flow, is characterized by massive alkaline to transitional basalt as exposed along the stream
bed. The recharge area stretches Far East and north of the village to the regional water divide
stretching N-S. The relatively elongated catchment area, presence of fractures and cracks,
exposed phonolites, volcanic extrusive plug prevails damming effect of surface and groundwater,
Presence of weak zones, river water forming an ox bow type structures, and presence of
productive hand dug wells are indicative parameters to consider the area as promising
hydrogeological site for drilling.
The Regional Water Well Drilling Enterprise also drilled a well to a depth of 70m on the
extrusive plug type structure but dry and abandoned. Similarly, there was mis-location of the
drilling site. It could have been out of censure, if it was drilled up stream of the plug type
structure.
For better justification further Geophysical investigation performed to confirm the presence of
groundwater and depth of abstraction, Geophysical study analysis verified in section 2.1.5.
The newly selected site is pinpointed upstream of the northern bridge at a position of 37P
373042E and 1257964N at an Elevation of 2344 m.a.s.l.
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Figure 6; Geological map of Gult area.
L..egend
• Loc,ation of' study area
Faul
- Road
River
Town
C+~ Gult new BH location
,0 2-5 5
·- -Geology
Tertiary
15 20 Kilometers
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Figure 7. Hydrogeological Map of Gult area
Legend O 2 4 8 12 1,a
Kilometers
• Loe tlon of udy r -Fault - Rod Ttiwn
Geology Tertiiary
PNlb T m b ,ousse) Form t1 on alkalln to transit! nal basalts oft n form in~ sh, Id vol.c no s w,u, mmor trachyte and p onolites plugs
r2s A,hllngi torrn~llon: Alkaline end trans~ ion,0,1 basaltic flows with rare I nlerc.a1 ation s. o nu ff
Gult new BH location
Hydrog1eolog1ical classification
Fractun~d aquifers with moderate productivity
Fraclures aqui1fers witli law to moderate producUvity
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2.1.5. Geophysical Survey
The geophysical Survey was conducted along the perennial river at a relatively flat land. The
maximum electrode spacing was AB = 440m.
The VES survey result revealed seven contrasting resistivity layers, the first layer shows reddish
brown soil cover, underneath of the first layer weathered intermediate basalt, with a resistivity
value of 3.5 ohm-m with thin thickness is characterized by highly weathered basalt and
transported colluvial deposits. The low resistivity value at this depth is the influence of the river.
The third layer is attributed to weathered and fractured basalt with a resistivity value of 18 ohm-
m with a thickness of 7.3m is characterized by weathered and fractured basalt with water bearing
formation. The fourth layer is attributed to massive basalt with a value of 256 ohm-m with a thin
layer then follows relatively low resistivity value 15.6 and 9.08 ohm-m with a thickness of 7 and
161m, respectively are characterized by fractured and weathered basalt and/or trachy basalt. The
layers are prevailing semi-aquifer property. The last layer is characterized by massive basalt
and/or trachy basalt. Based on the geophysical data signature the site is feasible for drilling of
wells to a depth of 180m.
100: ' ' ' ' ' Pa ' ' ' ' ' ' ' ' ' ' ' ' ' 0 ' ' -- ----~ ------~ ---- ' ' ' -- ··r·-----
"" ---- ,-------,-----' ' ' t ' ' ' ' ' ' ' ' ' ' ' ' ___ --:· <-' ' v ____ ' ' ' ' ' ' ' ' ' ' -----~------~---- ,~ .. _______ , _____
' ' ' ' ~ - ' ' ' ' ' ' ' '
0 ' ' ' ' ' ' ' - ' ' ' - ' ' ' ' ' ' - ···r······ ----- ----- ------ ---- ~-------,-----
' ' ' - ' ' ' ' ' ' - ' ' ' ' ' ' ' ' ' ' ' -----~------J----- ••••• L •••••• ~ ••••• - - - - - J. - - - - - - _,_ - - - -
' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' AB/2 1 ' ' ' ' ' ' ' ' ' ' ' ' 1 10 100 1000
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Layers
Resistivity
(Ohm m.)
Thickness (m) Depth (m)
Probable formations (interpretation)
Remarks
1 12 0.8 0.8 Reddish brown soil
2 3.51 0.6 1.4 Weathered intermediate basalt
3 17.9 7.3 8.7 Highly Weathered basalt with colluvial deposit
4 256 5.2 14 Massive basalt
5 15.6 7 21 Weathered and fractured Basalt and/or trachy basalt
6 9.08 161 182 Weathered and fractured Basalt and/or trachy basalt
Water Bearing formation
7 213 substratum infinity Massive basalt and/or trachy basalt
Table 1. Geophysical Interpretation Result of Gult area
N p h d Alt 1 12 I 0. 775 I 0. 775 -0. 77 ~ 2 3.51 0.587 1.36 -1.36: 3 17.9 7.33 8.69 -8.69: 4 256 5.23 13.9 -13.9: 5 15.6 7.05 21 -20.91
6 9.08 161 182 -182. 7 213
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2.1.6. Environmental aspects for the off-site of Gult health center
Literally, the environmental impacts that could arise in the course of implementing such projects
are of two types; pre-operation and post-operation impacts. It is very important to forward some
remarks regarding environmental aspects of the water well drilling and water pumping from the
safe guard of the environment and as well as for sustainable and environmental friendly use of
the well.
There are no hazardous industrial wastes and practice of mechanized farming in the area that are
potential sources of risky contaminants. The excepted groundwater pollution is from bacterial
contamination from human and animal wastes as a result of poor hygienic and sanitary practice
from the upper catchments driven by the stream water. However, these are the most common
type of contamination to be managed by grouting the upper portion of the well section and
continuous chlorination of the well and storage tanks as well.
Drilling by its nature is less destructive, and has less disturbance of physical environments,
displacement of households etc. In the pre-operational/drilling/ phase, the project has less and/no
adverse effect on the environment, since the project needs a few square meters of area, and
displaces few volume of sub-surface soil and rock to the surface. Moreover, the drilling method
uses clay, foam and air that have negligible negative impacts on the surrounding areas.
Moreover, water to be pumped out from volcanic terrains has suitable chemistry for domestic,
agricultural, and industrial uses. No salt or toxic substance pumping is expected from such wells.
The daily water abstraction anticipated from this well is less that has negligible effect on ground
water table depletion and associated land subsidence.
In order to control to pollutants, preventive measures has to be taken during water well drilling.
The following and other appropriate measures should be taken to avoid any contamination of the
aquifer.
Appropriate cleaning and disinfection of the well has to be done after borehole
construction with recommended chemicals.
Pumping of the well should be as per the recommended safe yield and over pumping
should be avoided.
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The well has to be protected with sanitary/surface casing grouting, well head to seal
runoff and waste water percolating into the well.
Water quality has to be checked before use checking the compatibility
Periodic Water quality Monitoring has to be done for safety issues.
2.1.7. Conclusion and Recommendations
The main goal of the study is to verify the sites proposed in the preceding phase of the study
located in and out of the center, and propose best suited sitting of the well so that safe and
adequate water is abstracted for the Health Center. So as to achieve the goal, maximum effort
and different disciplines were incorporated one after the other. After a thorough investigation and
discussion with the team, the only possibility for Gult Health Center is drilling of a deep well
off-the compound about 780m North West of the Health Center along the perennial river.
As has been depicted in the geological part of the document, Gult Health Center is located on a
steep local water divide drained outward to the south and north, small catchment area, exposures
of fresh and massive basaltic units associated with very poor fractures and cracks network
favoring runoff rather than infiltration, moreover the dry and abounded well at the vicinity of the
Health Center obliged the team to look after outsides of the compound.
The North West catchment which is taken as promising hydrogeological area is comprising
elongated catchment area, presence of fractures and cracks, exposed phonolites, volcanic
extrusive plug prevails damming effect of surface and groundwater, Presence of weak zones,
river water forming an ox bow type structures, presence of productive hand dug wells and
geophysical signature are indicative parameters to consider the area is promising
hydrogeological site for drilling.
Land ownership in the Ethiopian context is public owned. There is only lease right for small
holder farmers. Thus, when a physical project for community use lies or passes on a land where
its lease right has been occupied, the local administration will arrange modalities for the project
owner for compensation of live crops, houses or plantation and loss of advantages for few years
time. Land is to be made available for project implementers after settling the above few issues.
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In the case of Gult well site, the identified well site lies on communal grazing land owned by the
local administration and the pipe line route follows an existing foot track for about 500m length
of the route. The rest route passes on barren land. Hence, compensation of crops and structures is
avoided to the minimum and/or negligible.
Analysis of geological, Hydrogeological and Geophysical investigation should be completed by
pinpointing abstraction point. Before going directly pin point sitting physical parameters that
help for sitting was assessed. Accordingly Position of the well is pinpointed at 37P 373042E and
1257964N at an Elevation of 2344 m.a.s.l. upstream of extrusive plug type structure (near the
northern bridge) which prevails a damming effect. The site is selected at a common graze land of
the localities. Hence, there will be no any conflict with the intended project.
Water samples from nearby areas in this area are classified dominantly as Na-HCO3 and Ca-Mg-
HCO3 type; whereas few springs show mixed type water with SO4 and Cl. Sodium and Calcium
are the dominant cations followed by magnesium. The water type is classified as suitable for
human consumption, industrial and agricultural uses.
The following points was considered for sitting
Topography of the area with in the area of interest.
The geological/structural set up of the area.
The closeness of the site to the compound.
Pipe lay out path that couldn’t create conflict with private land owners.
Project cost through avoiding anchorage construction and other civil works.
Reducing collapse problems during drilling
Considered Hydro power Electrical Transmission Line, which is under construction (for
future use)
Risks to Groundwater pollution.
The study has been concluded on the following conclusions and recommendations.
A hydrogeological setting of the project area is site specific and comprises relatively
favorable area for ground water storage and utilization.
The annual amount of rainfall is enough to replenish the exploited ground water or the
out flow from the basin.
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The Water Chemistry is under the range of WHO and Ethiopian standared as taken
before.
Ground water utilization is promising from borehole with an average yield of 2-4 l/s
and anticipated drilling depth is 180m of depth.
Type of drilling method is predominantly DTH ROTARY with bit diameter of 9 7/8”
(Bit dia = 9 7/8”) and surface casing diameter should 12 inch and thus drilling for surface
casings should be carried out by 14 inch drilling bit.
Steel Blind and Perforated or Screen Casing should have an outer diameter of 6 5/6’.
The well site has to be fenced and guarded by metal poles and wire mesh of 25m2 for
security purposes.
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2.2. Maksegnit
2.2.1. Location
Maksegnit is located in Amhara National Regional State in south Gonder Merab Este Woreda. It
can be reached to the site through Jara Gedo Town, which is third grade asphalt road to Jara
Gedo Town and then 17 km to North through the only dry weathered road. The health centre is
under construction and close to the final stage.
Figure 8. Gate to Maksegnit Health Center
2.2.2. Physiographical set up of Maksegnit area.
The study of Physiographic features and identification of geological structures and drainage
patterns is done by interpretation of Enhanced Thematic Mapper satellite images at a resolution
of 30*30 meters. In order to confirm the observed SRTM detail investigation has been made by
Geo traverse.
Maksegnit, like its neighboring Gult site is physiographically located in the North-western
Highlands of Ethiopia, inside the main sub basin of Guna mountains catchment that rolls from
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Guna mountain peak down the Blue Nile Gorge. The area is drained by two major streams
surrounding the village on both sides before they merge as one to form the water fall south of the
village.
The village is located on hilltop overlooking the Blue Nile gorge southward. Two major streams
form the confluence on aphanaitic basaltic flows NE of the village where the previous borehole
site was located. These streams are draining extensive valleys from Jara gedo area to the main
Blue Nile River. The Health Center is located at a local water divide on a relatively elevated
ground aggravating run off than percolation.
Development of soil is very poor in the area; the thickness varies from very few centimeters to
very few meters downstream of the village. The prominent soil type is reddish brown clay soil.
The vegetation cover is also poor except along the stream embankments.
The area receives precipitation from its uni-modal rainfall pattern annually from June to
September. Maksegnit is classified as humid sub tropical / weina Dega / based on the Ethiopian
Agro-climatic zoning. The mean annual temperature is 14-18 0C and the mean annual rainfall is
1000-1200mm annually
Development of soil is very poor in the area; the thickness varies very few centimeters at the
Health center, and its thickness increases towards the perennial elongated river catchments. The
prominent soil type is reddish brown. The vegetations covet also poor very poor.
2.2.3. Existing Water Supply
The villagers usually fetch water from unprotected intermittent springs at the foot of hills and
mostly from Zeray stream located NE of the village, about 1km away, accessed through a
moderately steep slope and winding foot tracks. The sources are usually contaminated with
bacteria and worms where water borne diseases are prevalent in the area
2.2.4. Geology and Hydrogeology
The terrain is an igneous volcanic terrain composed of the trap series. The village area and its
vicinity are composed of thin layer of residual soil underlain by tertiary volcanic rocks. It is
dissected, rugged topography over the Blue Nile River catchment.
Supplementary Final Groundwater Investigation Report at Four Health Centers
24
Transect walk made with team members to evaluate significance hydrogeological importance of
the outcrop rock characteristics across and along the slop towards elongated river catchments.
The exposures are characterized by massive alkaline to transitional basalt with minor cracks and
fractures. The seepages emanating at the foot of water divide and direct precipitation doesn’t
have significant role for groundwater percolation. Hence, an intermediate and deep aquifer
groundwater storage and movement expected at a distance rather than direct precipitation.
The local aquifer systems can support low yielding boreholes if drilled around. The area is
characterized by Moderate to low volcanic aquifer systems. Based on the desk and field survey
results, Maksegnit area is classified as Low groundwater potential area because of its geologic
makeup and geomorphology. Considering small amount of water demand of the Health center it
is possible to abstract groundwater at a depth. To determine the depth and confirm presence of
water geophysical survey made inside the compound.
Supplementary Final Groundwater Investigation Report at Four Health Centers
25
Figure 9. Geological Map of Maksegnit
0 2.5 5i --• loca ~on o s dy area Geology
- , aul Tertiary
- Roa
River
C•~ Maksegnit new BH location
0 15 20 Kilometers
Supplementary Final Groundwater Investigation Report at Four Health Centers
26
Figure 10. Hydrogeological Map of Maksegnit
3700)0 l75000
Legend 0 2 4 8
4IIOOOCI
16 Kilometers
• Location of study area _ Fault _ Road Riv r .~ Town
Geology Tertiiary
IT]
. . -
PNlb T mab CGtJSS ) Fonnetl on, elkalln to transit! nel basalts oft n form inf.I sh1 Id vol<:ano s w1lh minor trachyte end phonoll tes plugs
r2a Ashongl form8Uon Alkalme end transitional bssalbc nows with rare interca1ation!i o f tuff
Maksegnit new BH location
Hydirog eolog ical c lassificatlon
Fractured aquif rs with moderate productivit y
Fraclures aqui.fers with km to moderate productivity
Supplementary Final Groundwater Investigation Report at Four Health Centers
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2.2.5. Geophysical Investigation
The Geophysical Survey was conducted in the compound of Maksegnit Health Center. The
maximum electrode spacing was AB = 1000m.
The VES survey result revealed ten contrasting resistivity layers, the first layer shows dry
reddish brown soil cover characterized by a resistivity value of 745m with a thickness of 0.5m,
and then follows a thin wet zone with a resistivity value of 22 ohm-m with a thickness of 0.5m is
attributed to wet soil. The third layer is massive basalt with a resistivity value of 210ohm-m
having a thickness of 2 meter. Following to this a thin weathered basalt with a resistivity value of
15.7 ohm-m is interpreted. Massive layer with resistivity value of 322 ohm-m interpreted over
the six and seventh layer, these layers are considered to be a shallow water bearing horizons with
a value of 40 and 67 Ohm-m, their thickness is about 10m. Hence, from a shallow aquifer at a
depth of 20 to 25m groundwater can be extracted. The Eighth and the Ninth resistivity layers are
characterized by high resistivity value comprising 237 and 162 ohm-m with a thickness of 266m,
which is thick and aquiclude horizon are attributed to massive basalt. The substratum is
characterized by moderately weathered and fractured basalt and/or trachy basalt interpreted as a
water bearing horizon with small amount of water.
Based on the geophysical data signature the well can be drilled in the compound of Maksegnit
Health Center to a depth of 300m.
Supplementary Final Groundwater Investigation Report at Four Health Centers
28
P a I I I
I I I I I I -----~------, ---- - -----r------,- ---- - - - - - T - - - - - - -, - - - - -1 I I I
I
I I
I
.----.---~-'
I I ---- - .--- --- , --
I I I I -----L-- ___ .J __
I
---L I
I I I -r----- -,- ---- -----T -- - - - -,- - - - -
I
I I I I I I
- - - - - L - - - - - - J - - - - - - - - - - J. - - - - - _,_ - - - -I
10 AB/ 2 ~-~~~~~~~-~-~~~~~-~-~~~~
1 10 100 1000
N I e I h d Alt 1 754 0.45 0.45 -0.45(] 2 22.2 0.467 0.917 Lo.91 6
3 210 2.16 3.07 -3.07 4 15.7 4.06 7.14 -7 .1 3 1
5 322 5.84 13 -12.9 6 40 2.56 15.5 -15.5, 7 67.5 7.19 22.7 -22.7 8 237 60.8 83.5 -83.5 9 162 205 289 -289
10 I 16.5 C
Supplementary Final Groundwater Investigation Report at Four Health Centers
29
Layers
Resistivity
(Ohm m.)
Thickness (m) Depth (m)
Probable formations (interpretation)
Remarks
1 754 0.45 0.45 Reddish brown soil
2 22.2 0.5 0.9 Wet Reddish brown soil
3 210 2.16 3.00 Massive basalt
4 15.7 4.06 7.14 Weathered basalt
5 322 5.84 13 Massive Basalt and/or Massive trachy basalt
6 40 3 16 Moderately Weathered and fractured Basalt and/or trachy basalt
Water Bearing layer
7 67.5 7.2 23 Moderately Weathered and fractured Basalt and/or trachy basalt
Water Bearing layer
8 237 60.8 83.5 Massive Basalt
9 162 205 289 Slightly weathered basalt
10 16.5 substratum infinity Moderatly weathered and fractured basalt and/or trachy basalt
Water Bearing layer
Table 2. Interpretation Result of VES in Maksegnit Health Center
2.2.6. Conclusion and Recommendations
The study in this specific site is conducted for the possibility of relocating the well sitting inside
the compound Health Center. Previously, the consultant has based its assessment on the best
possible and feasible hydrogeological site to supply water to the center without any defined daily
water requirement of the center. As a result, a well site relocated back to the compound with
possible depth adjustments after further geophysical data verification in the compound.
Based on the geological, hydrogeological and geophysical investigation inside the compound the
well can be drilled to a depth of 300m. The proposed well site inside the compound at a position
of UTM37P 378328E and 1250101N
Supplementary Final Groundwater Investigation Report at Four Health Centers
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Water samples from nearby area like jara gedo are classified dominantly as Na-HCO3 and Ca-
Mg-HCO3 type; whereas few springs show mixed type water with SO4 and Cl. Sodium and
Calcium are the dominant cations followed by magnesium. The water type is classified as
suitable for human consumption, industrial and agricultural uses.
Ground water utilization is poor from borehole with an average yield of 0.7 to 1.0 l/s
and anticipated depth of drilling is 300 mbgl.
Type of drilling method is predominantly DTH ROTARY with bit diameter of 9 7/8”
(Bit dia = 9 7/8”) and surface casing diameter should 12 inch and thus drilling for surface
casings should be carried out by 14 inch drilling bit.
Steel Blind and Perforated or Screen Casing should have an outer diameter of 6 5/6’.
Supplementary Final Groundwater Investigation Report at Four Health Centers
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2.3.Gulem Dengin
2.3.1. Location
Gulem Denjin is located in Amhara National Regional State, west Gojjam zone, Burie Woreda
about 15kms from Burie town of Gojjam on an all weather gravel road. The Geographic
coordinates of the health center location is UTM 37P 292400E, 1170838N, Elev. 1982m (WGS
projection)
Figure 11. Get to Gulem Dengin
2.3.2. Physiographical set up of Gulem Dengin area
Gulem Denjin village is Located in Burie Woreda of Amhara National Regional State. Gulem
Denjin site is physiographically located in the North-western Highlands of Ethiopia, as part of
the Blue Nile basin recharged mainly from Chokie mountain ranges. The village is surrounded
by a relatively deeper extensive valley aligned west to east situated north of the health center
than its rolling gentler plain in the south. There has been ample experience of drilling shallow
Supplementary Final Groundwater Investigation Report at Four Health Centers
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wells by the Regional Water Resources Development actors where about 5 shallow wells fitted
with manual pumps are operational for community use but all wells are located in the southern
plain area.
Development of soil is moderate in the area; the thickness of soil in the low lying plains accounts
to some meters of depth overlying the basaltic flows. The prominent soil types are reddish brown
clay soil to black cotton soil. Eucalyptus is the common type of vegetation found everywhere
apart from cultivated farms.
Gulem Denjin area receives uni-modal rainfall that lasts from June to September. The mean
annual rainfall is characterized by high mean annual rainfall ranging from 1100-1200mm. The
mean monthly minimum and maximum temperature ranges from 10-14 0C and 16-20 0 c
respectively.
2.3.3. Existing Water Supply
The villagers usually fetch water from shallow wells almost all of them drilled in the southern
gentle plain fitted with manual pumps. There are about 5 of them with depth ranges of 60m to
80m including the recently drilled well that is yet to be operational. A new shallow well drilled at
a location recommended by our previous report for the Health center, but information about well
characteristics couldn’t be found easily.
2.3.4. Geology and Hydrogeology
The terrain is an igneous volcanic terrain composed of the trap series. The village area and its
vicinity are composed of residual soil underlain by tertiary volcanic rocks. It is dissected, rugged
topography over the Blue Nile River catchment. The local aquifer systems can support boreholes
to be drilled around. The area is characterized by porous media and volcanic aquifer systems.
Based on the desk and field survey results, Gulem Denjin area is classified as low to moderate
groundwater potential area.
Supplementary Final Groundwater Investigation Report at Four Health Centers
33
Figure 12. Geological Map of Gulem Dengin area
Legend
Gulem dengin new BH location
Supplementary Final Groundwater Investigation Report at Four Health Centers
34
Figure 13. Hydrogeological map of Gulem Dengin area
2.3.5. Geophysical Investigation
The geophysical Survey was conducted in the compound of Gulem Dengin Health Center at a
relatively flat land. The maximum electrode spacing was AB = 660m.
The VES survey result revealed eight contrasting resistivity layers, the first layer shows black
cotton soil, beneath lays wet soil. These two layers extending to a depth of 1.2m, and then
follows massive basalt with a resistivity value of 156 ohm-m with thin thickness reaching to 3m..
The fourth layer is attributed to weathered and fractured basalt with a resistivity value of 18
ohm-m with a thickness of 7.3m is characterized by weathered and fractured basalt with water
-I ;
1-:: d
~ Gulem dengin new BH location
) • ' ,:
Supplementary Final Groundwater Investigation Report at Four Health Centers
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bearing formation. The fourth layer is attributed to weathered and fractured basalt with a
resistivity value of 18.3 having a thickness of 3m. A massive basaltic layer underlain with a
resistivity value of 1288 Ohm-m with a thickness of about 5m, and then follows moderately
weathered basalt with a thickness of 12m. The seventh thick layer is attributed to massive basalt
with a thickness of 52m. The last layer is characterized by moderately weathered and fractured e
basalt with a resistivity value of 50.5 Ohm-m with an infinity thickness. Based on the
geophysical data signature the well can be drilled to a depth of 150m.
1000~ ' ' ' ' ' ' Pa ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ~-----~------~ ' ' ' ' ---- -----r ---------- - - - - - - y - - - - - - -,- - - - -
' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' - ' ' ' ' ' _____ ,_ ______ ,, ---- _____ .. _____ ., ___ o---·-----
' ' ' :~ ... ' ' ' ' ' ' ' ' '
100 ' ' .,
' ' £ 1 ' ' ' >- ' ' --. ' ' ' -----r------~---' ' -----r- ---- .. ----
>- ' ' ' ' ' ' ' ' ' ' ' ' >- ' ' ' ' ' ' ' ' ' ' ' ' ~- ---_._ - ____ J ---- -----L------~----- - - - - • J.. - - - - - _,_ - - - -
' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' AB/2 10 ' ' ' ' ' ' ' ' ' ' ' '
1 10 100 1000
Supplementary Final Groundwater Investigation Report at Four Health Centers
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Layers
Resistivity
(Ohm m.)
Thickness (m) Depth (m)
Probable formations (interpretation)
Remarks
1 212 0.5 0.5 Black cotton soil soil
2 61.2 0.8 1.3 Wet soil
3 156 1.4 2.6 Massive basalt
4 18.3 2.3 5.4 Moderately Weathered Basalt
5 1288 4.34 10 Massive basalt
6 52.7 12.6 22.3 Weathered Basalt Water Bearing formation
7 738 52.1 74.4 Massive basalt
8 50.5 substratum infinity Weathered and fractured Basalt
Water Bearing formation
Table 3. Interpretation result of Gulem Dengin
N p h d Alt -
1 212 I o.427 0.427 -0.426
2 61.2 0.78 1.21 -1.201
3 156 1.37 2.58 -2.58"
4 18.3 2.78 5.36 -5.36~
5 1288 4.34 9.7 -9.7
6 52.7 12.6 22.3 -22.21
7 738 52.1 74.4 -7 4.4: 8 50.5
Supplementary Final Groundwater Investigation Report at Four Health Centers
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2.3.6. Conclusion and Recommendations
The borehole site in this specific site is relocated to the health center compound after all the
necessary investigation is conducted in and outside the center. As usual, depth adjustments are
made here also after considering the topographic differences during shifting assisted by the
geophysical log data obtained during the second survey.
Water samples from nearby boreholes in this area are classified dominantly as Ca-HCO3 and Na-
Mg-HCO3 type; Sodium and Calcium are the dominant cations followed by magnesium. The
water type is classified as suitable for human consumption, industrial and agricultural uses.
Hence, the new well site location sited inside the compound is at UTM37P 292400E and
1170838N (WGS projection).
Ground water utilization is poor from borehole with an average yield of 2 to 3 l/s and
anticipated depth of drilling is 150m.
Type of drilling method is predominantly DTH ROTARY with bit diameter of 9 7/8”
(Bit dia = 9 7/8”) and surface casing diameter should 12 inch and thus drilling for surface
casings should be carried out by 14 inch drilling bit.
Steel Blind and Perforated or Screen Casing should have an outer diameter of 6 5/6’. In
this case the consultant recommending Steel castings for the reason that in some cases
drilling might extended beyond the target depth due to different unseen reasons. From our
experiences drilling companies don’t show willing to install PVC casings if the well is
below 150mbgl. Considering our experiences we are supposed to recommend steel
casings. However, in the bill of quantities the price of PVC stated as well, which has to
be considered during contract agreement.
Supplementary Final Groundwater Investigation Report at Four Health Centers
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2.4. Gerbicho
2.4.1. Location
Gerbicho is located in SNNPRS, Sidama zone, Aleta wondo wereda, 11kms from Aleta wondo
town on an all weather road partly covered with asphalt. The health center is located at
Geographic coordinates of UTM 37 + 438277E, 723717N, elevation 1989m (WGS projection).
2.4.2. Physiographical Set up of Gerbicho
Gerbicho site is physiographically located on the west facing slopes of the South Eastern
highlands of Ethiopia, within the main Ethiopian Rift. The eastern escarpment of the Rift is
sharply defined and owes steep and sharp slopes while ascending from west to east. The area is
densely vegetated and hills around the foot of the escarpment are dwelling areas where Gerbicho
is one of its type.
As a result of its topographic break and occurence of steep slopes, ground water table has better
chance to cross ground surfaces expressed in the form of low yielding springs and water oozing
contacts around the foot of hills.
There has been no previous experience of drilling in this village rather tapping of natural springs
and reserving the flow is quite common practice.
The Development of soil is moderate in the area; the thickness of soil in the low lying plains
accounts to few meters of depth overlying the basaltic flows. The prominent soil types are
reddish brown clay soil to black cotton soil.
Project areas located in SNNPRS Region are dominantly classified as Humid Sub Tropical
(Weina dega) and cold humid sub- tropical, dominated by distinctly bi-modal (two peak) rainfall
pattern. Rainfall is well received from September to November and March to May. The mean
annual rainfall of the project area and its surrounding are characterized by high mean annual
rainfall ranging from 1000-1200mm. The mean monthly minimum and maximum temperature of
the study areas and its surrounding area ranges from 10-14 0C and 16-20 0 c respectively.
Supplementary Final Groundwater Investigation Report at Four Health Centers
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2.4.3. Existing Water Supply
The villagers usually depend on protected springs with concrete storage reservoirs located at the
foot of hills after descending down on sharp and steep slopes. In most cases, the spring discharge
decreases with the offset of the wet season and gets replenished considerably in winter.
2.4.4. Geology and Hydrogeolgy
The terrain is an igneous volcanic terrain composed of the trap series. The village area and its
vicinity are composed of residual soil underlain by tertiary volcanic rocks and in few cases by
the Rift formation. The local aquifer systems can support shallow to medium boreholes to be
drilled around. The area is characterized by porous media and volcanic aquifer systems.
Gerbicho area is classified as low to medium groundwater potential area.
Figure 14. Geological Map of Gerbicho area
Geological Map of Garbicho Area -
P ng • S r alf.h Center
2 3
Legend
Geological Structure
Roads
II
+ [±] Garbicho new
BH location
I
Supplementary Final Groundwater Investigation Report at Four Health Centers
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Figure 15. Hydrogeological map of Gerbicho area
2.4.5. Geophysical Investigation
The geophysical Survey was conducted in the compound of Gerbicho Health Center at a
relatively flat land. The maximum electrode spacing was AB = 440m.
The VES survey result revealed seven contrasting resistivity layers, the first layer shows black
cotton soil, beneath of it lays weathered basalt. These two layers are extending to a depth of
1.5m, and then follow weathered basalt with a resistivity value of 22 ohm-m with thin thickness
Hydroeological Map of Garbicho Area
Supplementary Final Groundwater Investigation Report at Four Health Centers
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of 2m. The fourth layer is attributed to massive basalt with a thickness of 4m with a resistivity
value of 340 ohm-m. The fifth and six layers are relatively moderate resistivity value are
attributing to Slightly to moderately weathered basalt with a thickness reaching to 148m The last
layer is characterized by moderately weathered and fractured water bearing basalt with a
resistivity value of 50.5 Ohm-m with an infinity thickness. Based on the geophysical data
signature the well can be drilled to a depth of 180m.
N 1 2
3 4 5 6 7
1000 Pa I I I I I I
- - - - - , - - - - - - 1 - - - - - - - - - - r - - - - - - , - - - - - - - - - - T - - - - - - -,- - - - -I I I I I
I I
.--.... I I
.......... --~-- ---J-- - - - - - L - - - - - - _. - - - - - - - - - - .L - - - - - - -•- - - - -
I I ----- ______ J ____ _
I I I I
I I I
I
I I I I
-----r------,-----
I I _____ L ______ J ____ _ I I I I
I I I I I I
0 - T - - - - - - -,- - - - -
I I I I
I I
- - - - - .L - - - - - - _,_ - - - -I I I I
: : AB/2 I I
10 100 1000
__e h d Alt 34.6 I 0. 755 0.755 -0. 75~ 206 0.694 1.45 1-1.44~ 21.9 1.62 3.07 -3.06~ 340 3.71 6.78 -6. 771 104 9.07 15.8 -15.8~ 90.5 139 155 -154.~ 33.2
Supplementary Final Groundwater Investigation Report at Four Health Centers
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Layers
Resistivity
(Ohm m.)
Thickness (m) Depth (m)
Probable formations (interpretation)
Remarks
1 34.6 0.7 0.7 Black cotton soil soil
2 206 0.7 1.4 Moderately weathered basalt
3 21.9 1.6 3.0 Weathered basalt
4 340 3.71 7.0 Massive basalt
5 104 9.07 15.8 Slightly to Moderately Weathered Basalt
6 90.5 139 155 Moderately Weathered Basalt
7 50.5 substratum infinity Weathered and fractured Basalt
Water Bearing formation
Table 4. VES interpretation result of Gerbicho
2.4.6. Conclusion Recommendations
The previous scheme types proposed was developing and pumping a series of springs located NE
of the health center. Taking in to consideration of the low water demand of the health center,
i.e 5,250 lit/day, it is revised to leave the idea of developing springs outside but to drill a deep
well inside the health center compound.
Based on Geological, Hydrogeolgical and Geophysical investigation the new well site is located
inside the compound is at UTM position of37P 438277E and 723717N .
Ground water utilization is poor from borehole with an average yield of 1 to 2 l/s and anticipated
depth of drilling is 180m. In line with this we are recommending the following points for future
consideration during drilling
Supplementary Final Groundwater Investigation Report at Four Health Centers
43
Type of drilling method is predominantly DTH ROTARY with bit diameter of 9 7/8”
(Bit dia = 9 7/8”) and surface casing diameter should 12 inch and thus drilling for surface
casings should be carried out by 14 inch drilling bit.
Water samples from nearby boreholes in this area are classified dominantly as Ca-HCO3
and Na-Mg-HCO3 type; Sodium and Calcium are the dominant cations followed by
magnesium. The water type is classified as suitable for human consumption, industrial
and agricultural uses.
Steel Blind and Perforated or Screen Casing should have an outer diameter of 6 5/6’.
USAID/Ethiopia U.S. Agency for International Development
US Embassy, Entoto Street PO Box 1014
Addis Ababa, Ethiopia