Birete Dam Project - Geological Investigation Report Summary

MINISTRY OF MINES, ENERGY AND HATER RESOURCES
LAND AND WATER STUDIES AGENCY
BIRETE DAM PROJECT
GEOLOGICAL INVESTIGATION REPORT
1
*7.
February 1981 ADD 15 ABABA
. ~ ’v -w rf’~-Ministry of Hines, Energy and Wpier Resources Land art! Water Studies Agency
EIHETF EiEJ PROJECT GEOLOGICAL INVESTIGATION REPORT
by
Nsfia Ahn!Rd  ON En<inssrinig Adviser
(
Aklilu Assefs, senior Geologist, EIDS
BunteyEhun Halle* Engineer* LtfSA
February, ig#i AUDIS ABABA
%1
BIEETE DAM PROJECT GEOLOGICAL INVESTIGATION REPORT
ABSTRACT
The geological investigation report covers the geclDgical mapping for the Diretc Dais site and includes & geological eross-section along the axis cf the dam. Nine boreholes have been logged and the permeability tests are conducted in four holes. The foundation is assessed 
as competent for building the dam. Prospecting for construction materials m carried out and the test results are appended. Recommendations are included regarding the use of construction materials.
i2
TABLE OF CONTENTS
Itea
ABSTRACT . ..................... ..  . ................................................................. 1
TABLE OF COMTEKrS .................................. -................ ..  2
I.       Introduction. ........................ ......... - 3
?. Basin digcription.............................. ................................ ..  3
J.      Previous Viork.................. .. ............................................... .. ..4
1. General Geology of the Area............................................................. ..  4
i. Dam Hite {J&alogy................................................... ..  5
Prillings  ........................................ .. ................................................ ..  6
1
'. Permeabilitj  testSi*................................... ...................... ..  7
Cons true tian materials............................................................ ..  8
i. Reconniendations.................................. .. ..............................___________ .10
L Appendices ..................... *..................... ... .................. ♦ ♦♦«,„ .,14
■1. Introduction
The Birete 2am study was initiated by building material corporation in collaboration with the Ministry of Mines ■ Energy and Water Resources.
Engineers from land and Water studies agency and geologist from the tfthiopian Institute of Geological Surveys closely investigated the Birete river basin to identify all the possible dam and reservoir sites so that sufficient water will bE stored. The investigation was not limited to the indicated requirement of water 2000m^/day for the cement plant but also considered other needs and uses of water inorder ta have the optimum utilization of the water which could be stored in the reservoir.
2 ■ Basin Riseription
Birete rivBr  is one of the tributaries of sodoble river
t
which drains into Mugher river tributary of Blue Nile river TEie basin extends between latitudes 9° 25' N and 9° 29' ft' and longitudes 33° Q3*E and j3° 20’E and covers an area of 38 square kilometres* Birete river orginates near
V’ajuturie village about 10km north of water-shed divide of Blue Nile and Awash rivers. The altitude in the oatchenent area varies from 2450-2670 metres above sea level and is characterized by undulating topography gradually sloping to the north. The top soil which is a residual weathering product of the basalt, covers moat of the cstchcment area end outcrops are rare. More then 95$ of the area ia an 
open grass land moat of which is used for agriculture and posture. Bore and Likimsg are the mein tributaries end join Birete river one kilometre south (upstream) of the dam site.- 4 -
3, Previous Work
Reoonnajssflnee geological nigj of the area has been prepared by D.EJ.Jebsen and M*j.Athesrn, tf.S. JJaparWnt of State dgenpy International development in 1963- ^yrfrogeophysicsl end geological invEstimations of the area wsre carried by Ethiopian Institute of Geological Surveys in 1973 and 1979 respectively- The preliminary llydrogeochysical study revealed that the under ground water potential!ty is limited and. the geological investigation indicated the geological condition 
of the Dam site and construction materials.
fitting
Thirty four pits were dug along the two previously proposed dam axis designated qs profile f-I and II-II in tha geological report of December T£79- Profile I-rl 13 Vflty close to the final dam axis. The average thicknEss of ovtrburden in profile 1-1 for 16 pits is about 2,^0 metres and in profile
II-I1 for twelve pits 2.90 ftetrea.
I- Oenerol Geology of the Arae
the srec is located in the central Ethiopian plateau series of basalts which e&nsistsof the following stratigraphic successions.
&} upper besic volcenitcs
bl ignimbrites
&) lower basic volcanites
The basic unit is predominant in Blrete river basin and is underlain by thin ereateoeous sandstone  limestone
(
with gypsum, shale and marl intercalation at the base. Ths Triassic sandstone is exposed further north at theconfluence of sodoblE and Much61* river. Piffsrent leva
flows with poleasoil formation arc oacrvd in the dissehted 
part of the plateau.
jUong the hank of Bireta river the rocks are not well
exposed and almost all the rocks in the surrounding ridges
sit highly weathered and altered- The deep weatharLng of
the basalt has resulted in the formation of residual claya
2 4^5 metre a thick.
Major faults are not observed in the vicinity of the Ban
site, however according to D.H.Jebstn Dnd Murray J.Mhearn one major fault is shown further north (downstraamj from
the Dam sits.
5* Dam Site l^ology
The den site is situated about two to three kilometres
south west of the cement plant site, the arcs at the Don 
site end considerable areas down and upstream of it were mapped on the ecsle 1 ;2000,95Jfc of the mapped area is pevotpd by soil, as a result of detailed geological study in the
three patches of basaltic out crops, the' following joint direction and intensities were observed.
Outerop
I
Strike
Dip
Sot
110-120°                 40-55  WE      1
Spacing
15-2500
II
210-220°
vertical
to
4° 2
15-30dm
300-320°
M
III
290-310°
20 £
2
15-50cm
22O°-23O°
fin- 6 -
The width of the columnsr Joint varies from few millimeters
to flight niillimEtrefi on the surface which is probably due
to weathering, The joints are rtsirtly filled by calcite
or clayey material bb observed in the boreholes. Dus to 
the scarcity of outcrops it was impossible to calculate
the ooeffleant of jointings.
6- Drilling*
In Order to uhder-atand the exact nature Of the dsc Bite
nine bore holes, were dr it 1 Ed along the dSE axis r to 
a total of 173*40 linear aeteia, the cores were systematically 
logged. Bore logu are shown in sppEnJix I* Field permeability 
tests were conducted in boreholts Ng J, 4,7 and JJ. Results
of permeabilities at various locations appear in sooendix II, 
The subsurface features of the dem site were interpreted as
to whe the r grouting is needed or not * disturbed and 
undisturbEd samples from the boreholes wflre sunmittei to 
tha Building college and the physico-meohunical test results
are shown in appendix III,
Thin      sections      of      the      core      sample      revealed      the      following mincrallogicsl            composition.
Phenocrysts ofplagiocloser
ground mo S3  plagioclsae
pyroxene and ^u^ite
45^
pyroxene
<o£
/icc€53ory 
otho pyroxene magnetite (opaque)
According        to        the        obova        mineralogies!        composition,        the rock is augite basalt.- 7 -
Jis depict^ in drawing Ho. SW 1OT and cross-section in figure 1 along the <u<n axle, the following inforration ftUe deduced:
|> The centre part of the valley is deeply weathered and consists from top to bottom of clay gravel and highly weathered basalt, the valley elopes (sides) arc covered VtitK clayey detrital materials and weathered basalts.
2. At least two lava flows have taken place within the drilled death (30 metre} and the paleasoil formation with indication of peat and silty clay stone suggests that the area was swampy before the laat flow*
J. As shown in the cross section along the Dam axis an average of about 2.50 metres depth of clayey material has to be stripped off,
4. There is a confined shallow artesian ground water on the western terrace (left bank) of the river at and 
in the vicinity of Borehole No. 5 where the water was overflowing for several days. The water encountered in the other borehole and pits .has no relation with it,
7. Tct F.eab i J i ty_ Les t a
Permeability teats were carried out in four boreholes (ltd,?, and B) by numplng in teat method where Water is forced into the section of borehole under teat through drill rods (pipe aquiped with rubber packers), The interval of testing and the pressure applied varied according to the mater tola under test* It depended on the compactness cf the material under test tp hold the packer tightly in the bcrehtlo and it also depended on the weight of the notarial above the length of hole
■- 8 -
undcrtest. TIie minimum pressure applied was C.3 kg/cm
2
g
and the maximum 2kfr/cra .
Due to the physical condition of the material encountered
ot certain  depths undertast,, not performed  at those depth the following;
Borehole No 3
4 7 8
water pressure tests were intervals and are listed in
Interval 15.3-18.00m
0.00-14* OOci 0.00-5*00m 0.00-4-00m
The permeability coefficient results are 3hown in appendix II
0. Construction fraterials
a} Hock
The exposed basalt st Likirnsa river 500 metres south west of the dam site could be used for quarry. It covers an 
area of 3800 square metres and can be quarried with open pit to 10 metre doth. The other Exposure cf basalt la
700 metres north of the dam site, it can also be eo3ily quarried to 10-12 metres depth.
b) Clay
Three localities have been investigated, in the vicinity 
of the dan site.
i)          Plant Site
In order to use the clay to be excave ted from the plant
site phyaico mechanical testa on tho clay samples had been carried at the Building College but the clay type is net suitable for the construction af the dan- Teat resultsar& attached ag appendix IV,
ii)     Kotcha Creek
The clay area near kotcha creels 1? kilometre north east
of the dam site was investigated snJ "es found to be
satisfactory es a core material for dam purpose- ihe borrow
area is designated as 3A in the drawing* Test results ere
included as Appendix V, Relevant sanpie numbers are 118418 and 113078,
iii)       Hud-gcbeya
The clay occurrence near hud-gebeye is situated Jkm north 
west of the Dre site and could be used es core materiel
for doo- This borrow area is designated as j3 in ttiE drawing. Relevant laboratory test results for this borrow sxee are
alao given in Appendix V bearing sample Ros. 118417 and 118079
c) Transition Materials
i)    Weathered Boselt
The weathered basaltic rocks at Blys, area 7A snd near the church at Makoda, area 7B in the drawing DE 101, can be used sb traneition material.
ii)     Tuintu Banda tana
The friable sandstone which can he easily made into sand available at Tumtu, 14km a&uth of the dam, can ba used as a filter layer next to tha impervious core,
iii)       Sodcble River Alluvial Deposit
The river send in the salable valley has been investigated by pitting with an average dupth of 2 Eetrta, The sand is mixed with gravel, boulder and silty cmtariols in the following proportions.10 -
Boulder 50$, Gravel JO$, Sand 15$. Silt 5$. Grein size analysis revealed that the material could be used as a transition material after proceaaing but the sand proportion of the oaterial which can bs only obtained by screening is fine and La not considered suitable for mating concrete.
9+ Fecpmgiijnda tions
a) Foundation
i)     Perusal of the bore logs shows that the bed rock would provide a suitable foundation for the dam. Thera is no aarious weak spot in the foundation area. Localized thin past layer is encountered at u depth of 30m below the foundation level. The dam is about 20,5n high and considering load dispersion for the depth at which pest layer is encountered, its presence is not considered of
any serious consequence.
ii)      Permeability in the boreholes 3,4,7 and 3 shows that in hole No. 4 at depth l8.50ir, and in hole No.0 at depth 
-4 
22m, it ia 6.96 x 10 and 5-42 X 10 cd per Second 
-4
respectively. Artesian flow «bb also experienced in hole No. 3. In hole Mo, 4 permeability tests could not be conducted from 0 to 14m depth. In the light of the above information it i3 suggested that the arsa between horizontal distance 240 to 310 from the left abutment should be provided with a single line grout curtain for n depth of
18 metres.
In case the physical ootcntial for grouting ia not available the area from the impervious core to the upstream toe of tha doo could be provided with dental treatment and then the dental treated area could ba tied with a clay blanket11
upstreeo* Tyin^ of upstream clsy blanket nith the core
is not suggested in view of the very low shear psrazatres
of thE clay available*
b) Materials
i) Clay maternal for cote
Clay material has been tested in the Building College
laboratory. The facility for triaxiel testing is not
available. The values of internal shear angle indicated 
are hRsed on the direct shear tests.
Teat results of clay samples from the plant ar da (Appendix IV) indicate internal shear angles of 1° and 5°* This eoterial
is unsuitable for ths clay core.
Teat results of clay sumplaa frtun Sorrow area, Kotcha creek 
(3A) and Hud-gobayw (SB) appear in Appendix V und internal sheer angle values show a largo variation. Two samplea
No. 11Q417 from JB Borrow orca and No. I1d41<3 from 3A Borrow
□res were tested earlier. Since the sample No. 113417 
which had higher percentage of fines smaller than 2 microns and had higher liquK. lioit and plasticity index showed higher internal friction anglo compared to atmple So. 11&41S it was considered advisable to get rww samples from the two Borrow araoa and run the to&ta again. The tests ware repeated by s different engineer.. The na* results are
higher in both cusea. A comparision is shown bclowj-12 -
Sample
No
Borrow
area
L.L
P.I
Angle of
shearing 
resistance
Cohesion 
k/cm
unified soil
classification 
group symbol
110417
110418
JB
3A
70
64
43
36
23.0
15.0
0.10
0.16
CH
CH
118078
113079
3A
IB
76
75
49
46
26.5
26.0
CH
CH
Since the variation in the results is so much it wea considered advisable to use averagE values aa given in table 8, chapter
V of the book, "Design of Small Darcs by U.S. Bureau of Declamation. ■' The following shear parametres were adopted for the design of Sircte Den Embankment.
Anglo of internal friction, / = 15°
cohesion 
0*05 kg/cro
ii)     Transition material
Drain aizc curves from area 7 A sample No 110077 and area 7Br sample No 110000 are shown in Appendix VI. Though it is not a well graded material and is deficient in finer fractions
it ig conoidered that during transport and compaction it would produce finer fractions thot would improve its quality as
a transition material. The material from the area near the church is considered better, it is also nearer to the dam aite
and may be used,
iii)       Rock
Rock can be obtained, for constructing the rock-fill sones, from two locations, one from 500 metres upstream and the other700 metres downstream of the dea, The upstream location, though near, ie within the reservoir area. Rock quarry from that site would expose all the joints, fissures etc., which 
ceil be a source of leakage from the reservoir, unless the
quarry area after the completion is properly dressed and 
is covered with a clay blanket. In view of the above it is recommended that the downstream location which is about 700 metres north of the dam site may be Exploited as a rock quarryAPPENDIX I BORE LOGSLocality BERETE
8 H NqI
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To
Graphic log
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13-50
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baton
95
69Locality BERETE
B H No 2
Elevation
Frow
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75
1
ILocality Biretc
□♦Plh Ln.ffltttL ftaphlt
Elevation 114 7
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■.^==2—--Locality BERETE
e H No 5
Elevation 111-5
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water
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DarfcQFeyctav with vtofbered boialt
Ffagme^H
Highly wtafhared totaled bee all Bilk
» ly ctaymoltnol
10*15%
90
100
P PP
PPP
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IO $0
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95
65
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1------ ------------ JLocality BERETE
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75
1Locality BERETE M m t ei
B H No-7
Elevation 113 4
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Graphs k>q
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9 50
Wtath+rkd j&UMtd b-dkoAt with clayey
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Cla   fn i i>td wiih
55
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is
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Iotolily BEftETE
e-H Nob
Elevation III-1
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95
TBLocohly BERETE
B H No 9
El ever i on 1197
PiBBih in metir
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—~             ——
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9*
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95
75appendix it FIELD PERMEABILITY
TEST RESULTSComputation of Permeability Values
t
2
3
4
5
6
BH
No
Bore Hole
Depth
S)
Water
T^w Q
3
(«  /sec)
Water Loes
(g&)
Applied Pump Frees-'
ure             9.    ' Hi(Ke/chT)
Apolied Pump Press-
ure
Hi.(PSl)
3
4.67x1O’6 1.67x10'° 2.0 x10"5
1.3JX1O-5
9 x 10-6
7.4X10"2
2.64x10"2
0.32
2.11
0.14
0.5
0.8
1.0
1.2
i*3
7.1
11.38
14.23
17.07
18.49
■II
II
IP
II
+
7
a
fi*5o-'5iG
4.5 -7.2
7*20-10.40 10,40-13.05
13,.05-15.SO 15.80-1e
18.0 -22*20
14-17.36
17.36-20.80
20,30-24.54 24.54-27.56 27.56-30.12
5*0 - B.p
6-11*0
11*0 -15*0
4*0 - 7*0
7.0 -10*20
10-13
13-16
16-19
19-22
22-25
3,0 x10“5
4 x10"4
4.5 x10“5
3.3 x10‘7
4.67x10“6 5.67x1 o"5 7.83x10"5
-
1.57X1O-5
1.67X1O"5
3.33x1O~5
1.21X10’4
3.13xio“5
8.33x1 O'6
3.O3xio“4
0.46
6.34
7.24x1 O'1 5.28x1 O'3
7.4 x1<?“2 8.98x1 O'1
T.24
-
2.48X10-1
2.64x1O-1
5.29x10“1
1.92
4.97x1 O'1
1.32x1 0“1
4.81
-
0.5
1,2
1.5
1.8
2.0
0*4
0*5
0.5
0.7
1.0
1.2
1*5
1.5
1.3
-
7.1
17.07
21*33
25.60
28.45
5.69
7.1
7.1
9.96
14.23
17.07
21*33
21.33
18.49
-Computation gf Permeability Values
1 '        7
Applied Pump 
Pressure x 2.31 
(PSlx2-31)
16.43
8
9                  10
11
12
Head 
of
1 Water
Ho
Feet of Water H
( ft)
Length of The column 
Tested L ( ft )
C  =^—log“ T1 P 20L r
for
L £ 10r
k-M
ciu/flea
1
11*5
27.58
48.44
6.19x10" 3             1,66x1O-5'
26.29
32.87
1    22.15 I
32.0
64.87
8.2 8.06
10.5
5.81xld'3
5.13*10" 3
3.17x1O"6
2,53X1O”5
39.43
42.49
81.92
8.69
6,19xi cT3
1.59x10"4
42.71
52.33
95.04
9*02
5.97x1o"3
8,79x1O"6
Bi
M
II
II
H
11
r-r-
16.43
10.04
26.47
11.06
5.25X1O"3
9.12HO"5
39.43
a, 46
46.86
10.96
5.1 5*1 O’3
6.96x1o"4
49.27
7.05
56.32
11.38
5.02x10“J
6.45x1O-5
59-14
7,15
66.29
9.91
5*52x1O^3
4.4 ±10"?
65.72
7.15
73.44
8.14
6.60x10“3
6.65x1 (T6
13.14
22,77
35.91
9.84
5.45xlO"3
1.36x1O"4
16,43
32.01
49.24
9.84
5.45x1 o’3
1.37x10~4
16.43
7.71
24.14
9.84
5.45x10"3
5*6 xio-3
23.0
14.11
37*11
10.5
5.13x10-3
3.65X1O"5
32.8?
13-45
46.32
9.19
5.67x1o"3
6.46x1o-3
39,43
15.26
54.69
9.84
5.59x10"3
1,96x10“4
49.27
14.93
64.2
9.84
5.59X1O’3
4.33x10" 5
49.2?
12.8
62.09
9.84
5.59x10" 3
1.19x10" 3
42.71
9.60
52.39
9.84
5,5 9x1O"3
5.42x10"4PRESSURE TEST
ETHIOPIA!* BUILDING MATERIALS CORPORATION BIRETI DAM SITE - NEft' MUDAER
BORE HOLE No, 3
DEPTH  w
From
1
2.50  m.
To
2
5,00 m.
Pump Pressure Kg/em2
~
3
Start 4
CONSUMPTION T,*3 End
5230.5578
0.3 kg/cm
II
II
it                                                   11
rt
rt
El
ir
it
ii
II
ri
it
II
II
n
230.5552
230.5576
230.5590
230.5612 
230.5626
230,5598
230*5612
230.5626
230.5640
0.5 kg/cm2       230-5640       230.5654
II
H
4.50  m.
it                                          11
7,20 n,
0.6 kg/ciE
9
El
SI
II
II
II
ir
ii
II
II
1!
II
II
IT
It
II
II
n
ii
0,8 kg/cm
II
II
230.5654 230- 566B
230.5705
230.5717
230,5724
230.5729
230.5734 
230*5739 
230.5746 
230,5753 
7.20 m.
10.40 m.
u
1.0 kg/cm2       230.0725 
B
11
II
II
ii
n
ii
II
IE
!■
II
230,8800
230.8867 
230.8927
230.8987
230.5668
230.5682
230.5717 
230,5724 
230.5729 
230.5734 
230.5739 
230.5748 
230.5753 
230.5758
230,8800
230.8867 
230.8927 
230.8987
230,9047
10.40 m.
13.05 m,
1.2 kg/cm2       231.8315       231.6750 
h
rt
II
II
ii
M
ii
ii
ir
ii
II
H
13.05 m. M
15,80 m.
1 ,3 kg/era2
II
II
ii
1.1
11
n
ii
ii
11
11
H
16,00 m.
22.20   m,
II
ir
1.8 kg/ch2 u
__________
11
ii
II
231.8750 
231.9157
231- 9557
231.9957 
232,1830 
232,1875 
232.1905 
232.1932 
232.1959
232.2905
232.2905
232.2905
231.9157 
231.9557 
231.9957 
232,0357 
232,1875 
232.1905 
232,1932 
232.1959 
232.1986
232.2905
232-2905
232.2905
Water Loss M3
------—------- -
0.0026 0.0020
0.0014
0,0014
0.0014
0,0014
0.0014
0.0014
0.0012 0,0007
0,0005
0.0005
0,0005
0.0009
0,0005
0,0005
0*0075
0,0067
0,0060
0.0060
0.0060
0,0435
0.0405
0.0400
0,0400
0.0400
0.0045 0.0030 
0.0027 
0.0027 
0.0027
0*0000 
0.0000
0,00007DG
DATE
1!
Start
End
Duration 
(Min.)
Start
Completed
'7
S
7
10
11
is
3:20
3:25
3:30
3:35
3:40
3:45
3:50
3:55
2:00
2:05
2:10
2:15
2:20
2:25
2:30
2:35
2:50
2:55
3:00
3:05
3:10
3:40
3:45
3:50
3:55
4:00
12:50
12:55
1 :00
1:05
1:10
10:05
10:1A
10:15
3:25
3:30
3:35
3:40
3:45
3:50
3:55
4:00
2:05
2:10
2:15
2:20
2:25
2:30
2:35
2:40
2:55
3:00
3:05
3:10
3:15
3:45
3:50
3:55
4:00
4:05
12:55
1 :00
1:05
1:10
1:15
10:10
10:15
10:20
5  sir..
27/9/80
27/8/90
IP
Fl
H
11
tt
11
fi
H
T
n
n
R
M
m
IW
w
Hole disaster 100 C=- H-3.40=.*0.3 k$:/c='
L • 2.50 r.
n
M
It
. 2
'■
Ft
5  am.
28/9/90
23/8/SO
IF
II-
III
III
kt
LI
H
11
11
IB
II
IP
It
la
■r
FP
IT
■t
M
H
Ht
H-3.40=.-C.5k^/=
Hole disaster 100s.
5  mln.
■1
it
■1
H
29/8/flO
29/8/90
II
IF
EF
>1
II
i*
Id
11
5  sin.
II
11
II
kt
30/G/&
30/8/80
II
M
rl
kt
II
41
rl
!■
5  sin.
1/9/SO
■■
ir
ii
Ik
If
II
II
■1
1/9/90
H
n
F"
in
5  min*
3/9/*C
II
41
3/9/30
1i
M
4
H*6.75a.*O.5k$/ca2
L • 2.70 3«
■5
H-6.^5c. *0.3kg/e=*
Hole dlaxeter
1*9.’5a--1.2k£/c=“
1 3.20 a.
Hole diaaoter 85&bu li • 12.95ft. *i. 2 te/es?
1 - 2.65 e.
Hole diaae'.er S5st H»i5.95a.»l.3»ce/^
1 - ?.?5 a.
Hole diaacter T5ska H*21.95a.*l,3kg/ea'
1 • 4.20 a.
?oTTs f? 1VL ?J
1
(l fe froo j5aSC tc 18.00 ■iepth  10 found ta be the aa=r u previously tested column (Le. froft iJ,Q5 - 1^,80), Ue« fore
he column r.oi tested !■ taken to be the stue ata there te in't*-* previously tested coluz^n. 
y?" *£* pcrfomBd at depth frra 15.9© condition of t.-.e oolutn
_P ............... *
........MGROUND WATER LEVEL 1*1.6_ra
BORE HOLE No.-_4
nPDTW firl
CONSOllPTrON                     -     —
From
To
Pump
Treasure
Kg/cm2
Start
End.
Water
loaa m3
1
2
3
4
5
6
14<00 tn. 
11
17*36  m.
0. 5 kg/cnr
IF
It
ir
■r
if
11
ii
11
H
ar
ir
IF
11
H
if
ii
ii
IF
11  □
0.3 kg/cm
11*
11
IF
17.36  JSt
! 20.80  a.
H
11
n
ii
n
if
Er
n
o
ii
n
ii
ii
ii
n
Fl
1.0 kg/crc^
II
II
1*2 kg/cm
11
?
11
11
rr
IF
23.SO  in.
IF
11
H
11
II
II
II
24*54 itu
■r
1 .2 kg/cm
tr
ii
IF
11
ii
ii
24.54  nu
u-
ii
ii
27.54 HL<
1.5 kg/cm -
11
11
11
1.4 kg/cm2
II
II
11
El
II
n
ii
ii
ii
ii
1.3 kg/finT2
II
11
11
11
27*56
30*12  m.
II
11
11
II
■1
III
El
II
Ii
11
n
IE
n  > 2
1.5 kg/cm
IF
11
II
- j2
2,0 kg/cm
ii
IE
224-9340 225,O03S
225*0132
225.0222
225*0312
225-0402
225.0505
225-0605
225.0705
225.3710
225-4960
225.6170
225-7380
225.9240
226.0475
226.1700
226.2900
226,4100
226.5695
226.5808
256.5908
226.6008
226*6160
226*6313
226.6450
226.6587
226.6785
226*6790
226.6790
226*6795
226.6795
226.6302
226*6809
226*6890
226.6915
226.6927
226.6939
226*6956
226*6970
226.6984
225-0038
225,0132
225.0222
225.0312
225.0402
225*0505
225*0605
225-0705
225.0805
225-4960
225-6170
225-7380
225-8590
226.0475
226.1700
226.2900
226*4100
226.5300
226*5808
226.5908
226*6008
226*6008
226*6313
226.6450
226.6587
226.6724
226*6790
226*6790
226.6790
226,6802
226.6790
226.6809
226*6816
226*6915
226.6927
226.6939
226*6951
226,6970
226.6934 226*6998
0*0098
0*0094
0,0090
0.0090
0*0090
0.0103
0.0100
0.0100
0*0100
0*1250
0.1210
0.1210
0.1210
0.1235
0*1225
0.1200
0.1200
0.1200
0.0113
0.0100
0.0100
0*0100
0*0153
0*0137
0.0137
0*0137
0.0005
0.0000
0.0000
0*0001
0*0000
0.0001
0.0001
0.0025
0.0012
0,0012
0.0012
0.0014
0*0014
0.0014GROUWD WATER LEVEL 1,18 m,
BORE HOLE Mo, 4
TIME
DATE
Start
End
Duration (min*)
Start
REMARK
Completed
11 130
11:35
11:40
11:45
11:50
11:55
12:00
12:05
12:10
10:40
10:45
10:50' 10:55 11105
11 :10
11:15
11:20
11:25
4:15
4:20
4:25
4:30
4:40
4:50
4:55
5:00
2:20
2;?5
2:30
2:40
2:35
2:45
2:50
9:25
9:30
9:35
9:40
9:50
9:55 
10:00
11:35
11:40
11:45
11:50
11:55
12:00
12:05
12:10
12:15
10:45
10:50
10:55
10:00 11:1O
11:15
11:20
11 :25
11:30
4:20
4:25
4:30
4:35
4:45
4:55
5:00
5:05
2:25
2:30
2:35
2:45
2:40
2:50
2:55
9:30
9:35
9:40
9:45
9:55
10:00 10:05
5 min.
ri
n
in
II
II
11
11
II
5 min.
II
II
m
ir
II
11
11
11
5/7/80
5/7/ao
ir
ii
El
II
II
11
II
11
II
11
11
11
11
11
II
II
7/7/80
7/7/00
II
li
11
11
n
ir
n
■r
II
II
M
11
1.1
ir
:
5  min.
II
II
II
n
li
n
ii
0/7/80
11
11
II
II
11
ET
El
8/7/80
ir
it
ii
n
ii
ii
n
5  rain.
9/7/80
II
IE
II
11
n
n
M
H
■r
ii
ii
ti
9/7/80
11
11
11
11
II
n
5  min.
11
H
ir
ii
li
tn
10/7/80
11
11
It
rt
ir
ti
10/7/B0
ii
hi
ii
ii
it
n
Hole diameter 85 am, 
H«3.06m.+o.5kg/cm^
L - 3.37 it..
H"3.06m.+0.8kg/cm2
Hole diameter 85 mm. 8 - 2.58m,+1.Okg/cm^
0 “ 3,34 m.
8 ° 2,58m.+1,2kg/cm2
Hole dimeter - 85mm.
1      -      2.15m.+1,2kg/cm* L w 3.74m.
8 " 2.15m. +1.5kg/cm^
1
Hole 0 w 85mm.                 - -- = 2.1 8to. +1.41cg/
L - 3.02 m.
H«2,18m,+ 1 .Skg/cEi2
Hole dimeter -85mni,^,
H =■ 2»18m, 4-1.5kg/c-m "
c
1 “ 2-56 is.
.1 Bqq . -2, Okg/cni^
L
0
9
10
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BORE HOLS NoBORE HOLE. ;tc. _7
time .
DATE
Start
End
Duration 
(min .J
Start
Completed
7
S
9
10
11
9:30
9:35
9:40
9:45
9:50
10:00
10:05
10:10
10:15
10:20
2:25
2:30
2:35
2:40
2:45
2:55
3:00
3:05
3:10
3:15
3:45
3:50
3:55
4:00
4:05
4t10
4:15
4:20
9:35
9:40
9:45
9:50
9:55
10:05
10:10
10:15
10:20
10:25
2:30
2:35
2:40
2:45
2:50
3:00
3:05
3:10
3:15
3:20
3:50
3:55
4:00
4:05
4:10
4:15
4:20
4:25
5 min.
29/7/00
29/7/00
11
11
II
II
II
11
ll
IF
11
11
Fl
n
EF
■r
ii
ll
ii
n
11
Fl
If
II
cr
n
IF
II
ll
remark
12 
Hole diameter=*iOOmjn^ 6* 94m. +O*2kg/cm'
3.00 m.
2
6.94m*+0*4kg/cm
5 min.
1/8/80
1/0/00
H
II
H
H
El
■r
1!
11
M
IF
IF
11
II
h
il
ii
ii
ii
11
II
M
II
II
EE
II
11
II
Hole diamater^l 00mm. g 10.00m■ +0  *  Jkg/cn/ 3*00 m,
10. 00m* +0* Skg/cpT
5 min*
3/s/ao
11
n
IF
11
II
II
11
II
11
Ll
n
ii
ii
H
3/8/SO
Ll
11
II
11
cr
H
IF
Hole diamtteri100mm,? H = 12,25 tn.+0.8kg/cm L = 4*00 ra.
H = 12.25m*-t-1,2kg/cm'?Bore Hole ,No ______ S
f
■I
Depth (M)
Consumption (nr )
From
To
Pump
Prtjaure
Kg/cit^
End
Water      , Loss m‘
1
2
3
*
5
6
4*00 ffl. j
7,00 ro.
0.3 Kg/cm2
Ik
ir
IP
ii-
it
ii
1*
it
IP
if
it
il
ii
II
11
H
N
11
IP
tl
it
«
7*00 m.
»i
H
«
■I
ii
ir
IE
11
11
10,20m,
IE
0.5
0,3
M
IP
IP
ii
*
Fl
■1
ii
II
w
in
ri
0.7
ii
it
1r
10*00m*
13.00+
0*8
■i
ii
1!'
IP
IE
i       1"
IB
!'■
li
H
fl
II
11
11
Ii
«
■i
ii
II
1 .0 "
13+OOtn,
16.00m.
ia
H
il
II
II
ii
II
PI
il
II
1*0 11
II
n
ii
1 *2 n
ii
Ii
228.36*5 228.37OS
228.3756 228.3^10 228,365® 228.3906 228,3975
228,1(023
228,1*070
228,4725
228,1*80?
228,1*860
228.4913
228,4963
228,JOI 3
228,5116
228.5169
228.5219
228,5269
228,6510
228.6257
228.6352
228.6447
228.6537
228,662?
228.6820
228+6930
228,7035
228,7135
228.7235
226.7*15
228.7730
228+8038
228.8330
228.8622
228.8967
228.9330
228.9693
228+3700 220;3756
228+3010
228+3356
228,3906
226,395* 228,1*023 228,*O7O
228,1*1 17
228.*807
22B+*860
228,*913
226,*963
220,5013
228.5063
228.5169
228.5219
228.5269
22S.5319
228,6257
228,6352
228.6**7
228.6537
228.6627
228,6717
228.6930
228.7035
228.7135
228+7235
228.7335
228,7730
228*8038
228,8330
228.8622
228.891* 228,9330 228,9693 229*0056
O.0O63
0.00*8
0,005*
0,00*8
0,00*8
0,00*8
0*0051
0,00*7
0.00*7
0,0082
0,0053
0,0053
0,0050
0*0050
0*0050
0,0053
0*0050
0*0050
0 * 0050
0*0107
0.0095
0+0095
0.0090
0,0090
0*0090
0.01 IO
0.0105
0*0100
0*0100
0,0100
0,0315
0.0308
0,0292
0,0292
0*0292
0.0363
0.0363
0.0363Tian
Onto
Start
End .
Duration
(Mini.
Reoark
Start
1 COQP.
7
a
10
1 1
12
12*35
1200
1205
12 00
12i55
1 lOO
1 :10
1i15
1:30
12:35
12 00
1205
i2s5C
12:55
1100
1 8 TO
1:15
1 [20
1 fZ5
6 [50
iijij
7 too
71O5
?tio
7tij
7*25
7 i30
7:35
7:40
705
1 110
1:15
1i20
1:25
1130
l oo
105
1150
12 t40
12 [45
12:50
12*55
1 too
1:05
1:15
1:30
1:35
12:40
1205 121 50
12:55
1 :00
1 [05
1:15
’1:20
1 t25
1:30
6:55
7:00
7:05
7:10
7:15
7:20
7»3°
7*35
700
7O5
7:50
1:15
1:20
1 t25
1:30
U35
1 05
1:50
1155
5 min »
M
!■
1"
IE
11
n
11
■1
11
n
11
h
II
11-
ii
■ri
■1
H
H
H
n
h
H
N
11
it
it
It
Hi
II
it
ii
10/8/80
10/8/80
11
1!
H
ft
«
It
IP
11
■1
■1
H
IP
IF
It
4P
II
Hole $ p 100 pnu                                        2 U _ 2*J5 ni* * °*3 Kc/etn
L = 3.00 ei..
, 2
H - 2*35 n>. + 0*5 Kp/cm
11/8/80
T1/8/80
.
H
M
II
1!
II
11
II
11
II
It
It
II
ir
11
n
ii
11
pi
Hole 0 a 100 dm* 
H - 4,30 ta* + 0*5 Kfi/cra
L . 3*20 a*
H = 4.3Q id* + 0*7 Kr/cp
16/8/8O
H
H
II
■1
I"
II
If
II
II
IP
16/8/80
II
p
n
IP
II
ir
II
II
11
II
Hole 0 ■ WO ma... 
H • 4*10 cn* + 0,8 Kg/cm
L        2*80 Qi,
. ,2.
H a 4*^5 H!4 + 1*2 Kg/cra
?
18/8/80
18/8/80
n
■
11
It
IE
IP
it
ip
11
H
H
If
II
II
II
II
II
I"
Hole 0 a 85 EMfi#
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—— ~..r iiz?.- -jia.'—-<■
-Depth (hi)
Cons
1
-
uapption L® ) ——
Fro*
To
Pump
Pressure
kg/cn2
Start
End
Hater Loo a m'
1
2
3
4
5
6
l6,00m.
Il
■1
II
II
41
H
II
11'
41
19.0Qrn.
H
1.2 Kg/cm5
PI
Fl
it
n
M
M
ri
R
II
■1
R
II
II
1,5          “
1 9.00m.
22 B 00m *
IP
II
1!
H
■I
H
R
M
n
n
22. .<'Ora.
11
IP
ia
II
2 5,00111,
11
41
II-
IB
IP
IP
o
1.5
II
II
II
nl
■1
1.3
II
■1
ai
tl
229.0170 229.0252
229.032** 229,0332
229.0*52
229.0512
329,0635
229.0735
229.0829
229.0923
229.1907
229.19*2
229.1972
229<2000
229.2025
229.2050
229,3260
229,3310
229,*270
229,5160
229,6070
229.0252 229.032* 229.0392 229.0*52 229,0512 229.057a
229.0735
229.0829
229.0923
229.1017
229.19*2
229,1972
229.2000
229,2025
229.2050
229.2075
229.3310
229.4270
229-5160
229.6070
229.6980
0.0082
0.0072
0.068>
0.0060
0.0060
0,0060
0.0100
0.009*
0.009*
0.0094
0,0035
0.0030
0.0028
0*0025
0.0025
0.Q025
0,1050
0.0960
0.0910
0.0910
0.0910
?J OTl t
On bora holes Ni,
i B permeability testa were not
performed at the following depths respoct±v*lyf#
From 0*00 to £<50 th B p 0 B 00 to 1 QOip, 0< OO to 5 . OQ re.
and O.PQ to ■U.OO ij. b  due to softness of the
over-burdanvTime
Start             End
0
Da tc
10:35
IQ:  40
10:43
10:50
10:55
11100
1 1 1 10
11:15
11:20
11 (25
10:20
10:25
10:30
10:35
10:40
10:45
10:40
10:45
10:50
tO:55
11:00
11:05
11:15
11:20
11:25
11:30
10:25
10:30
iot35
io:40
10:45
10:50
Duration (Min )
■9 5 Min,
ir
ir
al
II
n
Start
to
19/B/0O
■1
Cosp.
1
Ij/0/80
N
ii
ir
11
■I
n
I?
ir
tt
IF
B
rn
H
l>
41
■I
M
!■
II
'll
II
H
u
It
II
It
11
RoE]»rk
12
Hole 0-85 ™.
H      4,55      a,      +      1-2      Kff/em L, ■ 3,00 tn.
H o 4,55                   + 1-5 Kg/cm2
2
20/B/80
It
■i
H
M
20/8/80
■
+
1.5 Kg/coi"
14
IP
Hole 0-85 man,
H s 3*90
L ■ 3*00 m.
!■
H
IP
12:10
12 :15
12(20
12:25
12:30
12:15
12:20
12:25
12:30
12(35
21/8/80
II
21/8/80
It
It
II
41
rt
Hole 0 ■ B5 Enm. 
H =■ 2.95 tn. + 1-3 K</cid
£
It
ii
L s 3.00
+ water table struck at
2^.20 jd. depth which
ro»ult<id is the continous rises of water to the
surface.APPENDIX III BOREHOLES SAMPLES
TEST RESULTSI
BI/ILlMNBT
No. 7*7*
SfiTtplc Nd- J6TCA-7&9
t
i ’           ■
J.'
MATERIALS RESEARCH and testing department
faculty of technology
ADDIS ABABA UNiVtHSITT
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IrH fc BUHHING MATERIALS
RESEARCH ANl I TESTING department
.WD'S
_________ ________
CERT
ENCL N,THE BUILDING MATERIALS -------------- ~ - research and testing department
GRAIN SIZE DISTRIBUTION
CERT    Na.    7C?2 ENCi. N, 3
♦
GRAIN SIZEAPPENDIX IV CLAY TEST RESULTS
PLANT SITEb
QMlilLfiriMfei T
Lei uhciie No 7416
Sample No 34494-495
MATERIALS research and testing department
FACULTY OF TECHNOLOGY
*&□!■                    UbWERSJtY
Addlfl Ababa
fe*l;
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td N U4>:
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Ethiopian Building Material* Ccrrcratton  Addie Abeba*
ikll auplua
The oil ant (c/o A to Bant eye bun Relle)
January 4i 1?BO
Birati - Jaw Huger
A to Benteyebun Helle
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■aaple description
? C — tefi/cs
- (degreae)
___        ___________  a (ka/tar) ___________________
A—1 
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^lature-dattaity relationship curves* plaaa
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MfjHE BUILDING MATERIALS ——'
RESEARCH ANO TESTING DEPARTMENT
CEHT N«
iDDlS
__________ ______
GRAIN size DISTRIBUTION
1
ENCL No
3•;. j: *'_______  i J i: ■;■ ■■- ■ J ■
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APPENBIX V
clay test results
KOTCHA CREEK - BORROW AREA 3A Samples 113419 &118076
HUB - GEBEYA - BORROW AREA 3B
T■
Stales 110417 4c 118079rtui.i.0iN»r
hV 759* Sumpie nd. y  734-7 .J5
3
MATERIALS research and testing department
M**
FACULTY OF TECHNOLOGY
ADDIS *BA1A WtVBfl-BlTY
Addis Ababo
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Mtarhcrg     liaita,     grain     size     awl;     si     fl     »     ffec     Swell,     specific direct ahair, shrirkaQB littlt und coriaction woii.fiod AASIlC-
TEST SHULTS
C’itnl’fi markin g
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z?g-              depth (ifi*)
Ll.i. Li- a e i ».
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l
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depth (it..
}
0 - in kg/cn 
resistance £ - decrees
Specific
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1&J17
1 
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2.72
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2 
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15.0
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 —
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—
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fa-ximum              Optiuiuci moisture
sWh
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dry-denei ty
* d-kc/dm-^
content
£
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116415
1 
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2 
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1.65
1.67
25.0
27.6
flj- .
---------------—            — 
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fat      £Tjin         a^z*      distributions,      P
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bob encloBtirafi 2-4-
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:MI-FIL.EXI.HlhT
l. L inlr-jt* No.  7766
simple No. 57407-408
MATERIALS
RESEARCH1 AND TESTING DEPARTMENT faculty of TECHNOLOGY
ADQiS 4Bi0^ UNiVBR^iTY
Add I* Ahab*
pw
EtLiOlm Buildltif Katarina 
Soil Ml>lu
Til<1 *M*nf (*A AtO Bant^lwn Bulla) February 6, LjBl
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TEST O 8 V L T S
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76       27        49        55
75       39        46        50
2fi-5
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1.iHt  ydil IJING MATERIALS
REStARf'1      AN.    i      IT    STING    OE    PARTMEE.    r j Oors * e i h -          ____________ ______________
■jHAIN, Size DISTRIBUTION
U- U4
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1
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_!_.U Lt’izizuIAPPENDIX VX TRANS ITION MATERIALi
*' ftpoftiii SwiLfiiHir
P q •%*
r*L. --**«**
L«iiwkal« frto. 76?f-
Samplt IS'O
£19
materials research and testing department
faculty of technology
APOC5 aiada UHiVIPMTY
Addl* Ababa
Client;                 Building Watariali Carjioratienn Addie Ababa.
TlM Ofe.teir
S-nnpkd fry:
1 i,ic Ra\iw*l-
2 narr.pl ee of
acetates
Iril
urnl oT lai
by:
Thn   client   (c/a   Ate   JLklilu   Aa^efa) Noveaber 16, igflQ
New Mu^iat
A  to  Akliln  AflJtfa SiflYt analyses
! i,^ r. i i ll.
TMt Ht*ullJi
Si eV* alia I .  Siwe Jnil;-ate test rsai;Jte, . (bv vni/ht^
(ASTH)
Sa, L]flO77
Coarse arzrojnte Mo. 11&080
As received
After
iaraeriion *nd
drying
Aa rocBivfeiJ
Af ter 43-krV iHMraUn  and irvina
2 ■•
2*
1*
3/4 *
3/8*
Ao. 4
No- 8 
Mo. 16
No. JO
Ko. 50
Ko.100
Mo.200
100 
a?
77 
55 
43 
32 
25
12
7
4 
3
2
1
1
100
96 
88
69
57
41
31
15
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96 
95 
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93 
70 
54 
40
24 
15
10
7
5
3
2
4
r                  "I
according to ths client'e request.y/THi ecHt-CFNG MATERIALS
“
resfa^h AN  testing department
n
aODrE ABflfi*
CERT fcu. r‘L4. ENCL Ko
GAAIN SIZE DISTRIBUTION
__    - —     —“ " 
" 
i a 111           J7 j.A'J
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j               CL^X £«•4
' IF -.

Summery

Report Date: February 1981
Location: Birete River Basin, Ethiopia (Latitude 9°25'-9°29'N, Longitude 38°03'-38°20'E)
Prepared by: Nafis Ahmad (UN Engineering Adviser), Akiliu Assefe (Senior Geologist), Bantayehun Haile (Engineer)

1. Project Overview

The Birete Dam study was initiated to store water (2000m³/day) for a cement plant while considering other water utilization needs. The investigation included geological mapping, borehole drilling, permeability tests, and construction materials assessment.

2. Basin Description

Area: 38 square kilometers
Altitude: 2450-2670 meters above sea level
Topography: Undulating with northward slope
Soil: Residual weathering product of basalt (2-5m thick)
Land use: 95% open grassland for agriculture and pasture

3. Geological Findings

General Geology

The area is part of the central Ethiopian plateau series of basalts with the following stratigraphy:

Upper basic volcanites
Ignimbrites
Lower basic volcanites

Dam Site Geology

Outcrop	Strike	Dip	Joint Spacing
I	110-120°	40-55° NE	15-25cm
II	210-220°	Vertical to 90°	15-30cm
III	290-310°	20° E	15-50cm

Drilling Results

9 boreholes drilled (total 173.40 linear meters)
Core samples revealed augite basalt composition (45% plagioclase, 40% pyroxene)
Average overburden depth: 2.50m (to be stripped)
Evidence of at least two lava flows within drilled depth (30m)

4. Permeability Tests

Tests conducted in boreholes 3, 4, 7, and 8 revealed:

Highest permeability at BH No.4 (18.50m depth): 6.96×10⁻⁴ cm/sec
Highest permeability at BH No.8 (22m depth): 5.42×10⁻⁴ cm/sec
Artesian flow experienced in BH No.8

5. Construction Materials

Rock

Upstream quarry (500m SW of dam): 3800m² area, 10m depth
Downstream quarry (700m N of dam): 10-12m depth

Clay (Core Material)

Borrow Area	Location	Liquid Limit (%)	Plasticity Index (%)	Shear Angle (°)	Cohesion (kg/cm²)
3A (Kotcha Creek)	1.5km NE	64-76	36-49	15-26.5	0.16
3B (Hud-Gebeya)	3km NW	70-75	43-46	23-26	0.10

Transition Materials

Weathered basalt at Biyo area (7A) and Mekoda church (7B)
Friable sandstone at Tuntu (14km south)
Sodoble River alluvial deposit (50% boulder, 30% gravel, 15% sand, 5% silt)

6. Recommendations

Foundation

Bedrock assessed as competent for dam foundation
Grout curtain recommended (18m depth) between horizontal distance 240-310 from left abutment
Alternative: Dental treatment with upstream clay blanket

Materials

Adopted design parameters: φ=15°, cohesion=0.05 kg/cm²
Preferred clay source: Borrow areas 3A and 3B
Preferred quarry location: Downstream site (700m north) to avoid reservoir leakage

Conclusion: The geological investigation confirms the Birete Dam site as suitable for construction with proper foundation preparation and use of recommended construction materials.