THE FEDERAL DEMOCRATIC REPURUC OF ETHIOPIA MINISTRY OF WATER RESOURCES
Ar.jo Dedessa Irrigation Project Feasibility Study Report
VOLUME - I
Survey and Investigation
VOLUME - 1(a)
Annexure - 1
Topographic Survey
Annexure - 2
Geo morphological
Investigations
Annexure - 3
Geological & Geotechnical
WATER WORKS DESIGN & SUPERVISION ENTERPRISE
W ASSOCIATION WITH
IHTTHCSKTIMEMTAI C0NSBITAMT5 AMD TtCHMOCFATS INDIA W LTD
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d ruki-Liin ih.1 IARJO-DEDESSA IRRIGATION PROJECT FE ASIBJ!L ITY STU p Y REPORT
CONTENTS OF THE REPORT
SERIAL
NO.
1i
VOLUME NO-
PARTICULARS EXECUTIVE SUMMARY
MAIN REPORT
2
3
Pan t - Report
Pan II - Maps 3 Drawings
ANNEXURES
VO L UME - I
SURVEY AN D INVETIGATION (ANN EXURE S - 1 tu J I
4
Volume -1 (a)
Topographic Survey, Geomorphologra! Studies 3
Geofogicai 3 Geotechmcafl investigation
Part I - Reoon:
5
6
Volume •1 (b)
Pad II - Appendices
VOLUME -II
NATURAL  RESOURCES  1  ANN  EXURE  S  -  4  to  3)
Forestry Energy & CafcWent Deueioomeni P an
?
VOLUME -III
WATER RESOURCES (ANNEXURES - 7 Io 11f
7
Volume • llija)
Meseoroic-S'tni 4 Hydrological 3 Hydrogeoiogcai Studies
Dam 3 Aopurterant Works
3
9
10
tl
12
13
Volume - III (o)
Pan i - Report
Part II - Drawing*
Irrigation 1 Drainage
Volume-III {c)
Part I - Report
Part II - Drawings
Hydraulic Structures
Volume - III (d)
Part I - Report
Part II - Drawings
VOLUME IV
AGRlCUTLRUE (ANNEXURES - 1 2 to 18)
14
Volume  -  IV  |a)
Soil Survey 3 La^d Evaluation
’6
16
Volume  -  IV  |b)
Agricultural Planning
Volume - IV <c)
Livestock. Fisheries. Agricultural Mechanization 3
Agricultural Marteliruj
VOLUME-V
ENVIRONMENTAL       ANO       SOCIO-ECONOMIC       ASPECTS
I ANNEXURES - IS to 25)
17
13
Volume-v (a)
Environment -Health 3 Socio-economic Aspects
Volume - v (b)
Organization 3 Management. Physical Infrastructure
Resettlement. Financial 3 Economic AnalysisANNEXURE- 1
TOPOGRAPHIC SURVEYArjo tadma Irrigation Project
Topographic Survey
WayZW?
Table of Contents
TOPOGRAPHIC 51'RVEY
Illi
^■nurviiirauiHii
I
1
1-
J.
4
Sr
b.
T,
liNTRODUCTFCHN -
RECONNAISSANCE
RESERVOJR AREA . .. ..
COMMAND AREA,,—............. ,
SAMPLE- AR£.U
mu.
■Villi Illi
IIMIIII
1
CONTROL POINTS/BENCHMARKS____________________
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a     USE OF SOFTWARE
Water Works Design & Supervision Enterprise [DAsBoeliEian irltii Inlcrconttntnial Cgnsu Rants and Technocrats Pvt LrriArjo Dedeua Irrtgsdon Project
Topographic Survey
May 2007
TOPOGRAPHIC SURVEY
1.
Introdu
ction
The
planning,
design  and
c
onstr
uction  of  water
resource
s  de
velopment
prefect
s  require
very 
detailed
knowledge
of
the
topographic  fea
tures  of
the
area  Acc
ordingly
detailed
topographic surveys have been earned curt for lhe dam 4 appurtenant works, reservoir area and 1he command area; and based on the details  of the survey  topographic  maps  on different scales  and contours  at required interval have been prepared to be used for planning and design of various components of the project. These are discussed below
2.       Reconnaissance
Prior to the start of the detaired surveys a rapid reconnaissance survey was made of the area from the previous Master Plan study document and 1.50,000 EMA base map to define the scope of work  and identify  lhe irrigable area and dam site. After thal a hand GPS Garmin 12xl instrument was used lor navigation and fixing the command area and dam site feature to be surveyed by total station al later dale
3.       Dam Site
After detailed topographic survey for the dam Site Che following topographic maps have been prepared
I)  topographic  map  of  dam  site  with  one  meter  contour  interval  on  following scales 1:500, 1;100Q and 1:2000.
ii)         Longitudinal  profile  at  15m  interval  along  dam  axis  and  also  along  lines parallel to dam axis at 2S m interval up to 500 m width on the both upstream and downstream of dam axis
iii)        Longitudinal  profile  along  the  center  line  of  spillway,  intake  structure  and proposed scheme of diversion
4,       Reservoir Area
The contour map with 1 C meter contour interval and scale 1 10 OOD for the reservoir area was  prepared by  generating contours  with Global Mapper since lhe area was  very inaccessible. The Digital Elevation Model {DEM) used for generation of one meter contour was based on 90 x 90 meter resolution image. National benchmarks were used to calibrate
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TopograpbteSurrey
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Ule contpun Subsequently  detailed ground topographic  survey  w» undertaken to take cross-sedions  across  the reservoir al five representative locations  spread over eniire reservoir Cross  sections  were prepared based on the actual lopography  survey  and contours devetoped with DEM The comparison of the two sets of the cross sections of the reservoirs area shows that lhey are quite m agreement with each other This shows (hat process adopted is quite reliable
5.     Command Area
The detailed topographic Surveys (or (he proposed command area indicating all tenures & natural dramage lines have been earned ou( and the topographic maps on scale 1 10.000 wlh contour interval of one meler have been prepared. Against a lentalive command area of 16.600 ha as  given m the TOR, the topographic  Surveys  have been earned Out for 27.000 ha Altogether, ine following seven topographic maps have been prepared fpr the command area
Topographic map tof Arjo UedtaM Imgaban Shm N(i 1 to t
6  Sample Area
Detailed topographic surveys for sample area measuring about 500 ha have been carried out anti topographic maps an scare I 2000 with contour mterv.il of 0 5 meler have been prepared These maps will be util-zed for detailed planning of rhe distribution system
7. Control Points / Benchmarks
A total of 72 control points were established and concrete pillars were constructed al all these control points fhe topographic survey has been transferred from Ethiopian Mapping Agency  (EMP) references  and connected to all project topo-maps  and references Permanent benchmark  has  also been established al al these points  The values. of benchmark along with location of these control points are available in fable 1 I
8. Use of Software
The topographic surveys have been carried out with the heip of r«al stations The delaiFs of the topographic surveys obtained from the field have been ted directly into the computer for processing and preparai+nn of maps on desired scale and requued contour interval The encoding of lhe surveying data to computer prggr^nrwne and processing to produce topographic maps profiles iayouls and boundary mark have been done by using LIS CAD Land C-AC surfer and crv«i designer software
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Arjf DedMsi IrrigiliM Project
Topographic Survey
Mij’DOT
Tlblr l.l Bench Mirk Dm
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EAST | WORTH
2427«l i Miwoejn 2*2l2< 912295.7465 J4KJC 943147 1124 242104 9430N.MII T4J9W 943260 2482
24JI II          943164 909
242756       941903.1133
242644        940626.6414
Z428O6          940661252
2UW      942055.7404 MJfW     | 942072 6493
242464 941619.0418 2*1213 942591.6461! 2*33)4 ■742566 9109 3*322* 942J19.334!
24JJ4B 942536.5806 243200 942463.1763 24120? 942476 4079 243272 '■4 7-ilH 671
24jm            M264IH7I
2*2n>  94 1931.5725
242746      94F890 ISJ4 2426U      91181# EH 12 242722 i    9418711 1|?4 239ft9| 1    V4261T 72 U
2i?25j p    944231 5579 237400       944208 8067
ELEVATIONE                                REMARK
1*31 293     . flW-C
1+01
euj
1335.41 r
1324.966
BM-2A(INS )
1391=683
BM-3
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BM-3A
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BMfl
1345 242
1317 652
BUG
BM 1G
1164 515
TP-GIt
I367.35S
1392 135
■420.167
TP G11A
BM-MA-I
ElMMA-l
1400.765
BM-MA-4
J 389.115
AM MA-5
■397.182
BM MA-6
I3W 131
BM.MA-7
1166 661
&MMA-0
1424,712
0M AX-2
1429 786
BMAX-1
1427 146            BMAX3
I4J1.OI9             BUAX-S
I4M6UI
flMAX-7
1 126 106
BM AX-7-BM AX-6
1362 275
IHtJUt
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BM-7A
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235574
1164.923
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6m m
214335
9417)0 0781
04.1660 nil
-M 7496 9271
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23*2]?       H7472.9771
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Topographic Survey
TtbFs 1J JCont.-.j Bench Mark Data
BAST
NORTH
REMARK
21W |
951991 M23
213386       933472.2572
215220    933511 7991
226698 . 94)655 6774
22664 1 943876.9281
224194 946721.1277
ELEVATION
1321 443
BU-lQ
DM IDA
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1334 721
2134281
_95]  143.3039
218004 J      951061.7923            i3H.ni
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BM-4GA
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217986 i 952161.2236
LUO 391
948347 24)7
HM-5G
215535
948J7J 2| p
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[umM
224929
I 95950077331399J)66 ]
11332222.884422
BM-MA-IJ
224507
950957 7891
1354 496
954043.6531               1541.758
221923      954039 8439
1536155              0.M-MA-I8
9)3980 2967                1442 464                0M-MA-I5
222145
i 95)9% 145! I
UM.fcCA-16
21802?
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1)16445
BMBz2 MAiToUlsU™ FCI80
951218 0548
itM-SZi-J I MA
224198
94678J.2 322
1325 772
BM MA’If
947IDU4IJJ1                  1322 789
221976      946759 317?
I ]6? 659             BMStVll
224340
946750 JH 5
951172 3198
1307 381
H.M BZ
935474 4432
I296 5JI
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1289 02 r
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Tabl« 1  9 iCofrL...) 0«nch MM □*»
LAST           NORTH              ELEVATION                             REMAAJf
11*40$
V'S             1410 95 1
BM M«S
217724 9591,3(1603* 1)12 II*
21'MS | 95900) TOO1 11120*9
COMMON Pt BM JrGugw A B«in,. COMMON PT OM l.Gugu A
|
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0M 1*
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211071 93*135 63)7
12*1 131
1299 371
6M-15A
B.M 17
2110)9
95*223 SI 12
1)02 771
BM I7A
22 W4
2297*7
235*77
■)*21<W42«
136$ M2
0MF3
Mini jm<            H*4 *27              BM F4
.. .
■14 592* 02 S2               I1I7.ITI               BM-1G
235*86       941850 8)03
1317011
BM-JG
2)7171              MiJIJ M4) 238005       945922 1101 2JAl'U       04 5422. JW
l)|6 5)1
1)19 4?1
A M14
B M14A
1)24 Ul               BM15
2J9HI     94 5554 94-76
lu'-flll
BM15A
24UMJ7   *■■ 1 «5ni hM9?             1)51 4*|               BM BZl
24014) 944*2? M?D2 13)1561
2M29? 0494)2 5391 1321 751
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2152*1      S5M5Sul$B
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211*35 956 HJL 4301
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Waiflr Works Design & Supervision Enterprise
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In AhiMlaUna *lth ImrrrjDLnfDlaJ Den ml tin ft uJ Trrltnorrits Pvt Lid.ANNEXURE-2
GEOMORPHOLOGICAL
STUDIESArji iMdusi Irdfuaon Project
May 2007
TABLE OF CONTENTS
TABLE DF CONTENTS
LIST OF FIGURES.....
1. INTRODUCTION,
f t GFwCPJt
1.2 Objectives UMEhiODOLOGv 
t
...J
111 >JI M IIM I11 ■*■ 11 ■
hi immim
a 4 Previous GEow>RPMaLOG*C*L Works 2. LANDFORM S DESCRIPTION OF TH.E AREA
2.1 General F’mvMGRAPH'y. .
2
,.3
2.2 LAN&SCAPf EVOLUTION
LIIUHIIMUI III
3.
FLUVIAL GEOMORPHOLOGY OF T
HE DlOESA
RIVER
3
.*
11 General
3.2 Stream Tvpf
11 ■ it-Mf • »»t
f •
.muiiiai nimi aii.i am
n)
3.3 LORGITUOWAI PROFILE ...
13
3* Entrenchment....
I I ITWf •tTT'TTf
._.I5
3 5 Channel Reaches.
16
3.6 Channel disturbance and response potential
RAJA HTDRAULICS AND RELATED GEOMOftFWC EFFECTS ON DlDESSA.
4.
IIIMIIIII III IIIIIJUHIllll IUIIH
RIVER CHANNEL...
4 1 GENERAL...
4 2 DaMON 1h£ (MfSA RimTA
5 FUTURE WORK ............. ......... .. ...............
5 1           StaoE’Time Relations
6. REFRENCES.........
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HIM* III I Mill Mill!
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M*J2W7
list of figures
Fig 2.1 Type of landforms around the Arjo-Dtdesa Irrigation Project Area . ......................... 5
Fig 2 2 Geafogtal units around Arjo-Didesa Irrigation Project area.....................
.7
Fig 2 3 Major Lineaments around the Aqo-DuJesa Irrigation Project area....................        8
Fig 3.1 Photographs of Didesa River features ..
Fig 3.2 Plan view of Didesa River around the Dam sic 
......... ........................... 11
....... 12
Fig 3.3 LongHudinal) cros^secfponal and plan view of major stream types...................... 12
Fig 3.4 Longitudi&l profits along lhe Dictesa River channel......................... .......................13
Fig 3.5 River across sections across the Didesa River.......................... ........ ..... 14
Fig 3-6 Types of channel entrenchment........................ .......... ....... ............................ >...... 15
Fig 3 7 Photograph of pool-riffle channel reach of the Didesa River, downstream □(
the Dam axis . ........ ......... ................... ....... -........ .....
Fig 3 9 The spatial distribution of reach types with a drainage basm
.......... ........ ............ 16
iin^%UShnC@Siar ■ ■ ■ in- ■ m--s
...... ...... . . ..................... . t ■           ■ . ■         ■■
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I]Arjtt ledmi irrictdco Project GeomorphDloft^nresdgiUona
GEOMORPHOLOGIC INVESTIGATIONS
1 .INTRODUCTION
1.1 General
May 2007
An understanding of landscape type of an area, river-and stream-channel response to both natural and human factors is necessary for addressing several important issues including 1t*e protection of property  and structures; dam-brldge-sde selection, design^ and maintenance; protection and rehabiMstion of riparian and aquatic habitat; channel capacity; ground-water levels, general aeslhebcs; and recreahon The channel bank  erosion that accompanies natural channel migration across a flood plem represents a constant threat to property and structures located m or near :he channel Human disturbances such as dams, channelization, in-channel sand and gravel extraction and urbanization introduce additional mstabiMy  to which riiws  and streams  adjust by  such processes  as  channel-bod degradation (erosion), channel-bed aggradation (deposdron of material}, and 'or channel widening These adjustments, which represent 1he channel's attempt to establish a new approximate equilibrium, pose additional threats to property, structures, jftd habitat located m or near the affected channels.
Channel adjustments are major concern for several reasons. A significant lowering of lhe channel bed poses  an immediate threat to bridge pier foundations  as  well as  buried pipelines and cables In addition, significant bed lewenng increases bank height and bank instability lhal may trigge* channel widening Channel aggradation raises lhe bed elevation, reduces channel capacity and increases the livelihood of flooding Any channel change that occurs on the mainstream rivers and streams also may migrate upstream on the tributaries where additional property structures. and habitat may be at risk Finally, any long-term channel adjustment processes atso may instigate or worsen local scour problems
1,2 Objectives
The mam aim of this study is to present landscape types in foe Arpo-Didesa Irrigation Project area and fluvia! geomorphology of the site, and predict future changes Lhal might be expected due io lhe proposed dam project through a combination of field observation data analyst and interpretation
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Geomorphologic [uTustlgatlotM
Haj 2007
Knowledge  Of  geomorpholgicBl  oondlions  of  an  area  can  be  used  to  plan  and  undertake economically a subsurface investigation and design
1.3 Melhodology
The ability to recognize both landforms and fluvial geomorphology of an area on topographic maps, aenal photographs and site investigation combined with a geologic knowledge of the area, is very important when characterising a site and when tocatmg poleniiai sources for construction matenals
Land-sat imagery  and aenaf photographs  interpretation combined wtto brief on-sile inspection were used to determine 1he geomorphology of Arjo^&desa Irngation projecl area near toe dam site The fand-sat imagery available is in 7 bands, is of 1:250. GOO stale taken to 2003. The image cover the project area and Ils environs, was used m constructing lhe preacoenvri.THSnt of toe project site in general The aenal photographs are those taken in 1973 and are 1 02. MO scale Stereoscopic  interpretation of the aerial photographs  was 
done to 1race lineaments, landforms and plan view of the River channel morphology around the dam site The site inspection nciuded studying depositional landforms, sediment types and channel geomelry. While on-si1e, photographs  of the stream channel and the surrounding physiography  has  been taken Analysis  of photographs-derived landforms description and channel information 13, included in assessment of the plaeoenvimoment and Changes in bank full channel Width and shape gf the channel upstream and downstream from the dam
1.4 Previous Goonriorphologlcal Works
GeofliorjtotJi'ogicBl investigations around lhe pro|ttot area nave lo date barely scratched rhe surface. These may have ma|0r implications for a design of an engineering structure on lhe Didesa River USBR (1864) slated thaL toe mam CWesa River around rhe dam site and in toe reservoir Hows on volcanic rocks from headwaters to toe approximate area of Qdesa-Wama function,  m  toe  bend  where  toe  River  lurns  to  toe  northwest  and  then  entrenched  in melamorphto rooks to (he rest of the way to lhe Blue Nile According IO V7APCOS 11890) and BCEOM (1998) studies toe NNW flow of the Didesa Rmer around lhe proposed dam site is controlled by faults. In the upper reaches the bedrock constituting the River valley is volcanic of Tertiary age
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2, LANDFORMS DESCRIPTION OF THE AREA
2,1 General Physiography
The Odesa Irrigation Project area and its  environ* are divided in to three physiographic regions. These are We Chdesa plane (1270- 1400m). uplands  ex  cham of ndges fl400- 25D0mk plateau (greater than 2500m) and pediments (Fig 2.1 a, b 4 c).
The CJidesa plane is found close to the Didesa River. The chains of ndges are rugged and dissected by the tributanes of Didesa River The prateau is found on top of the basanre ridges. The Didesa plane is covered by elkivial soils. They are mainly shy to sandy reddish brown and black cotton  soils, ar*  products  of  the  break  down  of granitoids and basalts. While  the  Plateau  area  being  made  oF  Tertiary  basalts  the  uplands  are  made  up  d Precambrian granitoids and Tertiary volcanic rocks (Fig 2,2). Pediments are gently sloping erosional surfaces, exposing volcanic and basement bedrocks or covered with a veneer of alluvium  that can  be  transported  off  the  pediment  Surface  wi|h  (he next  significant  flood flvenl
Lineaments wilh general 1rend of NE-SW, NW-SE and rarely N-S and E-W can be traced frwn aerial photographs (Fig 2,3) for the area Locally, the lineaments govern stream and river courses and atgimgnt of ridges They a<« mainly straight to curvilinear -.ath variable lengths
2.2 Landscape evolution
Knowledge of geological history helps us to understand the present-day landscape of the Didesa valley. Precambrian rocks are exposed in We uplifts surrounding the plateau in the Atp-Didesa area They  consist of highly  metamorphosed gneissic  counlry  rocks  intruded by  grenries  Approximately  9M million years  ago an east-west compression produced a continent scale North-South trending orogenic belt and the associated Precambrian rocks in western Ethiopia Different Ternary  to Quaternary  volcanic  rocks  1hat come through the regional fault lines and fissures characterize the rest of the bedrocit geology of the Aqo- Oidesa area. Surface deposits, alluvium, residual and colluvial soils cover ihe rwer valley and the stope areas.
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In Ethiopia and In the Arjo-DWess area landSMipe development since early Tertiary has been dominated by episode* of continenfrwitfe uplift. The epicaogenic uplffl Of Afo^Arstjia. chat do« r*Ot Involve deformation, which is reJatad Id mantle plume whose decompression melting generated an enormous oulpounng of large volume of magmaP fanned LM plfllMu volcanic regions in Ethiopia The fissures that MTMtf SS a COndUd far ll*e magma are created by upraised Sftd up parched landmass (proto rifting) n response 1o Ihese uplifts volcanic activity dominated tut almost nvers eroded downward, hill stopes repealed, and deep river valleys were formed Over Irma. Uhs* processes have resulted in me removal of Siibstamiar thickness of rocks from SCUM* large areas of exposing many of the formerly buried land present d?y Streams estabWshad their courses al thia lime and because they were lifted high above base level 1hey twgai to ngorousiy down cud Deep entrenchment of Streams and differential erosion Of the plateau began ait Ihra lime. The slream courses were established on flat lying undeformed strala. tn valleys such as 1hat of the Didesa, this process Of erosion is cwdmuing today. aflhOugh at 1 rate impeFCCpCiKn during a human lifehme
As rocks have been eroded deep river valleys have peen farmed. Separated from neghhonng valleys by Steep. Had-fapped escarpments or hills rising up fa '-300 m above lhe adjacenl valley floors The escarpmenLs and hills are mainly formed m volcamc rocks with trachyle and phonolite often capping iheSe escarpmenls or forming prominent, tioultfer- Hrewi ritfges Soli Covers are typically IhiCk bu1 grassy ground covers are extensive.
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Fig 2.1(a); Type erf lancHccms around the Arjo-Uidesa Irrigation Project Area
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Fig. 2.1 (a)
F.g 2.1 [c|
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runs
Fig 2.2: Geological units abound Arjo-Dicfesa Irrigation Project area
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l'ij> 2.3: Mapi I iiwoment* around the \ijo-Didesa hrie.mou Ph»ic<i area
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X FLUVIAL GEOMORPHOLOGY OF THE DFDESA RIVER
3,1 Genera)
!Uy2007
An understanding of the channel geomorphology of a river Is important for several issues including the protection of nparian (sireamside) resources; protection of wldlrf# habitat (for example, the in-stream habitat for the threatened Hippos), and bank stabifeatron related to property loss Also, such information may be important lor the site selection, design, and construction of dams
The focus of this study is the channel of the Didesa River, upstream and down stream of the Dam axis Throughout this  reach an anastomising. silt-bed channel characterises  the Drdesa River.
The Ddesa channel bed around the dam site » situaled on erosion-resistant bedrock.
Efiuvium in the Dicfesa River Valley is typified by Silt and clay with a basal layer of sand and
gravel The bank materials consist mostly of cohesive sift and clay that are relatively 
resistant to erosion compared to sand banks. Also the banks typically have partial-In
complete mature tree cover that may enhance or reduce bank stability al specific locations 
(Fig 3.1).
Along  its  couvse.  the  Didesa  River  is  presently  eroding  perhaps  upstream  areas  where  it's young  Pronounced  and  abrupt  changes  in  the  character  of  the  nrver  occur  where  it  flows from  one  rock  type  onto  another  For  instance.  when  developed  on  volcanic  rocks,  valleys are   characteristically   wide   and   the   river   meanders   within   broad   floodpla-ns   marked   by numerous   oxbow   and   abandoned   channels   In   contrast   on   basement   recks,   valleys   are narrower,  ihe  river  toBowS  comparatively  a  stra  ghter  course,  and  floodplain  development  is limited (Fig 2.2)
Traditionally the channel pattern of a river has oeen classified into straight, meandering and braiding types. However, a more recent classification incorporates ana branching (including
anastomosing) as a recognizable pattern The diversity in the channel patterns is caused due to variably of water discharge sediment load, bedrock outcrops ground slopes 
human achnratoes and tectonic influence. Tectonic movements change the gradient of a river
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and modify  the valley. Alluvial rivers  are not significantly  affected or constrained by  bedrock and flow through sediments  that have been eroded and deposited by  them or their ancestors.
3.2  Stream Type
From   the   Figs   3.1a,   3.2   the   Didesa   River   can   be   classified   into   Stream   type   DA   - Anastomlsing stream (FFg 3.3} based on the following characteristics:
Qenrtfjrh   Anastomising   narrow   and   deep   with   expansive   welt   vegetated   Pood   plain   and associated wetlands Very gentile relief with highly variable sinuosity. Stable stream banks
Landform/soJI/featurcs; broad, tow gradient valleys  'with fine ahuvujm/lacustrme. Anastomising geological control crealmg fine deposition wrih wen vegelated bars  that are laterally Stable with broad wetland flood plains
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Fig 3.1: Photographs of Didesa River features a) anastomising b) bank vegetalion cover ano o) silty tank material
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Fig 3.2 l Ptan view of Didesa River around the Darr site
Fig 3.3: Longitudinal cross-sect tonal and plan view of major stream types (Modified after Rosgen. 199-4)
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3J Longitudinal profile
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Plol of lhe relative elevation of a streambed from headwaters  to mouth is  called ils 'longitodmal profile'. The longitudinal profile of a stream is  generally  concave upward which is in accordance with lhe sleady  downstream decrease in slope. The longitudinal protte and
river  cross  section  of  the  Odesa  River  channel,  which  is  inferred  from  global  mapper  5
served  as  breaking  the  stream  reaches  into  slope  categories  that  reflect  profile  morphology (Fig  3,4  and  Fig  3.5).  Fig  3.3  represents  types  of  dominant  slope  ranges  of  major  stream types   (Rosegen,   1934)   The   Dltfesa   river   longitudinal   profile   can   be   classified   into   slope range  of  E,  with  a  dominant  slope  range  of  <  2%,  and  belongs  Io  those  of  gentle-gradient types.  Bed  features  generally  are  related  to  channel  slope.  In  such  rivers,  mere  is  a  little change  in  lhe  etevalron  of  the  riverbed  along  lhe  over  channel  They  are  also  chraclerised  by lack   of   high   derbis   transport   (Supply   limited)   and   absence   of   waterfaris,   bed   forms   are relatively   stable   Longitudinal   profile   also   mdicaies   a   stream   reaches   (Fig   3.4)   related   to slope  categories  that  rchtscl  profile  morphologies  fhal  is  10  say  Ihat  riverbed  features  are related  Lo  a  channel  slope.  ANuvial  bar  development  requires  a  large  wtdth’to-depth  ratio  and smaH  gra  n  easily  mobilized  and  aggraded  by  flow  Gradient  and  bed-  feature  relationships are ntegral to the delineation of Stream type calegones
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■870m
From Pos: 2421 19.67. 942S7B.49
To Pos: 243620.14
943141J J
1400 m
1380 m
1360 m
1340 m
1320 m
0m
670m
From Pos: 243102.00. 942300
To Pos; 243605.00,
942809 00
1380 m
1360 m-
1340 m
r
eam
1320 m
Fig
3.5:  River  across  sections  across 
the  Didesa  Rivera)  up  slream  of  the
Dam  axis  b)  at
the dam axis c) down stream of the darn axis Note Distances in between are indicated
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3.4Entrenchment
M1T2XXT7
An innportant element of delineation ift relationship Of a hwer to Ils valley or/and landform featwee. This  interrelationship determines  wtidher the river is  deeply  mosed or entrenched m the valley  floor or in the deposit feature. Entrenchment is  defined as  the vertical containment of r™er. the degree to which it Is  incised in the valley  floor. This  makes  an (■important distinction of whether ihc surface adjacent fo the channel is a frequent flood plain, a terrace or is outside of a flood prone are# The flood-prone area is defined as lhe width measured at an eievahon, which is determined at Twice the maximum bank-full depth The entrenchment raUd t$ the ratio of flood prone area to the bank-fol surface width of Iha channel Comparing the lealures  of River Dedesss  as  given in Fig 3.4 and Fig 3 5 with those in Fig. 3.6 fRosgen, 1994), it can be concluded that the Oidesa River belongs  to moderately  entrenched river with entrenchment rabo ol 1.41 - 2.2, typified by  a well developed floodplain
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3.5  Channel Reaches
Channel reaches  exhibit similar bed forms  over stretches  of streams, across  channel widths and ils  length The Didesa River is  characterised by  pool-nffte reaches  (Fig 3.7) in the length under study  It is  untorrfined by  valley  wait and consists  of oscillating sequence of bars, pools  and nffles  resulting from osciiratmg cross-channel now that causes  flow convergence and scour on alternating banks  of the channel Concordant downstream flow divergence on the opposite side of the channel results  in local sediment accumulation m discrete bars  Bed form and grain roughness  provide the pnmary  flow resistance m pool- ritfie reaches. Bed forms  in many  pod-riffle reaches  are relatively  stable morphologic features, even though the matenal formmg the bed is  transported annually  Pool-riffle reaches  are commonly  armored exhibiting a near hank  fijEl threshold for general bed surface mobility
Fig 3.7: Photograph of pool-nffle channel reach of the Didesa River Dam axis
downstream of the
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3.6 Channel disturbance and response potential
Response   to   environmental   change   varies   tor   different   channel   Reach   morphologies   are associated   with   physical   morphologies   and   the   environment   that   limit   the   range   and magnitude  of  possible  channel  responses  to  changes  in  hydrualic  discharge  and  sediment Supply.   The   specific   response   of   a   particufar   channel   reach   reflects   the   intensity   of disturbance  or  the  magnitude  of  change  as  well  as  the  conditions  cf  the  reach  Table  3.1 iltugtrale*  patterns  of  potential  response  for  Didesa  Rrver  channel  reaches  Lower  gradient pooto-rrtfle    reaches    become    progressively    more    responsive    to    altered    discharge    and sediment   supply   with   decreasing   ratios   of   transport   capacity   Io   sediment   supply,   smaller grain  sizes,  and  less  Ghannel  confinement  Pool-nfflB  reaches  as  ih  Gumera  River  project area  snows  potentially  greater  response  of  bed  surface  torture,  scour  depth  and  generally have   significant   potential   for   channel   geometry   response   to   perturfautatton   m   sediment supply   and   discharge   Changes   in   both   channaf   and   valley   storage   are   also   likely responses, as well as channel roughness due to alteration of channel sinuosity.
Interprjjjed Didesa River poor - riffle reach level channel response Potential to moderate changes in Sediment supply and discharges (» «likely to charge : = unhkely Io change) Table 3.1 (Modified from Montgomery and Bufingfon, 19971
Grain
Width De
pth Roug
hne
ss Scour
depth size
Sediment Stope Storage
Response
+
+
Reponsts 
segments 
consist
of
tower
gradient
more
transport-limited   reaches   m   which
significant morphologic  adjustment occurs  in response to increased sediment supply. The spafial distribution of source, Iransport and response segments  generally  reflects  the distnbution potential of impacts  and recovery  times  DHtribution of these segment types define watershed - scare patterns  « sensitivity  to altered discharge and sediment supply (Fig 3.7) Sediments  delivered to transport segments  rapidly  propagales  to downsUeam response segments, where sediment accumulates  Consequently, locations  in (he channel network  where transport segments  flow into response segments  indicate places  particularly susceptible to rmpacis  from accelerated sediment supply  Because response segments  aw sensitive to increases m sediment supply, mey are excellent sites for monitoring the effects
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of  upstream  actions  and  can  be  considered  locations  of  critical  importance  in  watershed monitoring programs
Fig 3.8; The spatial distribution of reach
types with
distribution of potential impacts and responses
D»desa River
drainage basin influences the to disturbance
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4. dam HYDRAULICS AND RELATED GEOMORPHIC EFFECTS ON DIDESSA RIVER CHANNEL
4.1 General
Majr 2007
A  River  modibcabon  by  a  reservoir  will  alter  significantly  the  flow  characteristics  the  channel cross-sections. and the longitudinal profile of a river.
Dam construction changes  both the discharge regime and sediment supply  downstream channels  resulting In channel incision, constriction or widening and changes  rn channel substrate. Studies  document channel incision and bed surface coarsening immediately 
down st re am of dams  in response to sediment impediment (Williams  and Wolman. 1984) Tributanes  channels  also may  incise in response to mainstream channel incision through upstream knick  point propagation from lhe<r confluence Decrease In discharge below a dam may  cause narrowing of actrve channel width. Tributaries  sediment inputs  downstream of dams  may  cause channel aggravations  and accumulation (Alien cl al, 1989) and accumulation of fine sediment because at decreased sransport capacity  resulting from dam construction Differences  in channel form and function affect the probability  of specific response to a given perturfoatran. Channel classification can aid interpretation and assessment of response potential by grouping similar physical environments
4.2   Dam on the Didesa River
The Didesa Rver channel is  a stable river channel, naturally  anastomises  across  <ts  valley over bme while maintaining approximately  the same aoiS-sectional shape It has  shown Ihai it has  a moderate gradient Therefore the expected changes  in channel geometry  due to damming of Ihe river may be used to infer channel instability
Reservoirs  can be thought of a$ permanent floods  that affect ihe river system upstream from ihe dam in a quite different way  than the annual floods, which lasted far only  a lew weeks  or perhaps  a mcrnlh. The planned reservoir will cover many  of the pools, riffles  and rapids across the reach of the Didesa River.
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Dants crap sediment in the upper reaches of reserve** where tnbirtartes enter the relatively quiet water of lhe reservoir and deposit sediment Io create deltas and wetlands, which can have effects on the environment that are both positive and negative
Downstream changes in the stream flow regime atlnbuted to che operation of a dam might be expected due to a decrease in the magnitude of peak  flows  and an increase in ihe magnitude of low flows. Also, post-dam suspended-sediment concentrations  could get substantially  reduced rmmediaftely  downstream from the dam. Farther downstream, several tnbutanes chai contribuie unregulated flow to the Oidesa Rnrer will moderate ihese effects
Dams  result  m  upstream  and  downstream  changes  In  a  river  channel  Upstream  from  (he dams a backwater pool is created, the depth and extent of which depend on lhe height of the individual dam and she slope of the channel Wflhiri thus backwater reach of the nver. lhe decrease in flow velocity may result in some deposition of material on the channel bed As lhe  water  flows  over  the  dam.  its  velocity  and  erosive  power  increase  The  potential consequences    of    these    effects    include    increased    channel   bed   and   bank   erosion rffimediately  downstream  from  the  dam  as  the  nver  expends  the  extra  energy.  Most  □(  lhe erosion occurs during hrgh flows when the nver's erosive power is the greatest Bed erosion may  create  a  plunge  pool  at  the  base  of  lhe  dam.  with  the  formation  of  companion depositional  bars just downstream as lhe river loses its ability to transport the scoured bed load  The  depositional  bars  may  divert  the  flow  toward  or  away  from  lhe  banks  Bank erosion  results  m  channel  widening  and  also  may  contribute  to  the  formation  01  the deposflponaJ bars The form and downstream extent of these effects vary from site to Site as affected  by  human-caused  and  natural  conditions  that  may  either  promote  or  inhibit  lhe nver's response to 1he overflow dams
Effects of damming w«ll change the character of the Ctdesa Jt wifl cause lhe water-surface area, the channel area and lhe sand bars to decrease The change m channel-surface area rs relatively easy to determine from maps and aerial photographs However, the thickness of sediment on the flood plains is not as easy to determine This stored sedimeni also contains targe amounts  of slcxed carbon, which is  of current concern to many  research scientists interested 4n rhe global carbon oubget (Stella rd 19^0)
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5- FUTURE WORK
Various  fcmns  of  channel  activity.  Including  widening,  tank  erosion.  meantar  movement, and  degradation,  have  been  identified  in  the  downstream  pad  of  the  Dldesa  River  basin. Because the channel spdlvrty wourd be intensified during the period following impoundment Of  stream  now  and  sediment  designed  reservoir.  Il  would  be  powuMe  that  part  of  the channel  changes  is  the  result  of  changes  in  hydrologic  regimen  by  the  reservoirs.  It  is desirable  to  investigate  this  possibility,  as  well  as  to  explore  feasible  methods  of  reducing the economic losses and enhancing Brie anwonmenlal character resu 1i ng from the channel changes
A  future  geomorphologic  investigation  should  be  able  to  provide  sediment  and  channeL geometry  data  and  interpretations  of  those  data  pertinent  to  1he  bank-stabilization  project. Therefore,  it  would  include  description  of  the  analyses  of  sediment  data  and  would  provide data and interpretations of the channel geometry of the Oidesa River.
An objective of the investigation might be directed to determine whether significant alterations in sediment size and supplies to lhe downstream pad of the 3 des a Rrver basin mpght occur in the future if changes  would occur, an additional objective would be to describe those changes  in quantity  with time The nformation may  be relaled Co man's effects  on land use and constnjctKin of the ma|or reservoirs  in Che Odesa basin and to natural effects  of topography, geology, climate, and physiography  To permd reasonable evaluations  of the area and temporal variations  in sediment yield, sediment stze. and channel characteristics. Che future work  should consider the entire Oidesa River tasm in parts, as  well as  from adjacent parts  of other drainage basins. The study  resutt would be able to report fluvial- sediment transport and channel morphology  data for the pe riod of extensive stream flow regulation in the bas«n and for the period -mmediately  preceding regulation All of Lhu data and generalizations  to be presented might be intended to represent controlled hydrologic  conditions  or uncondoned conditions  of a generally agricultural rather than a pristine watershed
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5.1 Stagg-TJme Re Fl Mons
[JhjuigeS in lhe elevation of a stream ch-an net wtth time provrifl an addili&nal mean 3 of evaluating channel Injtahilrty. Degrade  hen commonly occura <1 channels downstream from reservoirs. The water rebased from a dam 1$ largely sadimwit free and thus ha a a tendency to  re  glare  me  sedimanl  bad  1C»  an  amount  similar  to  lhat  Of  unregulated  Condition*  The KCtfrenre   and   airtent   of   charmrf   degradation   is   a   measure   of   the   imbalance   that   a reservoir  h3S   imposed  on  a  stream  Changes  slagt  (water,  level  erevatlpn)  with  time  rate largely  are  rotated  Lo  datum  changes  of  the  channel  bed  (aggradation  or  degradation) Changes of stage elevation for np^tJuraUon rale result bcm from changes of bed Elevation and  from  changes  m  charmal  cohvayante  a1  discharge  Mb  exceeding  those  equivalent  to the  act  rye.  channel  stage  An  explanation  of  Lhasa  trends  would  be  that  aggradalions  or degradation  Of  [he  Charmer  twd  U  nql  occurring.  but  that  me  relatively  targe  rebase  rates from the upstream reservoir are causmg erosion  of the channel sides be ow Lhe ban* full stage
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6. REFRENCES
Allen.   P  M.,  Hobbs  R   .  MMf,  N
1359-  Downstream  impacts  of  a  dam   on  ■  bedrock 
fluvial syslem Bulletin Qf the association of Engineering Geofogisfl 26. 165-189.
ECEOM. 1996. Abbay River basin inlegralod development master plan project
Httllay.   R   F   19S7   PodimwtS   and   pediment   fwmmg   processes   Jouma/   of   Geologtcai Education. 15  63-09.
P
Montgomery.    DR.    Buffington.    J.M.    1997.    Channel    Reach    morphology    in    mountain range drainage basi ns Geological society of American Bulletin 109. 596-611
Qsierkamp, R E, Crowther H .
1962 Sediment and channEl-geamelry
invesligaiions  far the Kansas  Riverbank'-slabihzation study  Kansas. Nebraska and Cciarado U S. Geological Survey. Water-Resources  I nvestigalions. Open. Fite Report 01-120
Rpsgen, D I 1994 A classification of natural rivers, Catena 22, 169-199
Mengesha,  I  Tadrwps.  C.,  WorkiHeb,  H.,  1996.  ExpJanabon  CO  ihe  geolOgruat  map  of Ethiopia, Scale 1.200090, 2nd edition Geological survey ofEttiiopia
USER. 1994. Land end waler resources of 1he Blue Mile basin
WAPCOE. 19M Prel.mmary waler resources development master plan f&r Eth+opia Williams. GP Wolman. MG 1984 Downstream effects of dams on alluvill rivers Lfmled Stales Geofogicgt Survey professional paper 1206 US Government Printing office. Washington DC. USA
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23ANNEXURE- 3
GEOLOGICAL AND
GEOTECHNICAL INVESTIGATIONSAfj® Dedessa Irrigation Project
Geological & Geotechnical Investigations
TABLE OF CONTENTS
Table of CONTENTS............ -....
list o f tables.
LIST OF FIGURES_______ __ - LIST OF PLATES-______ __ — 
U5TQF APPF-VEHCES........... .... .■ -■ i■ 11■ -—•!111rrr^tft■ ii" ■?»•»• i
LIST OF AfiRFVjATIOXS. ...
1.    INTRODUCTION—--------------------------------- ---
2.     INVESTIGATIONS             ____________ — 
2r (ifNiRAi
............ ............................................
2 2 Previous XHVEsntiATnN in the ajika 2.3          Objectives of die WEMNT ttwr  _
24
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Supervision Enterprise
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4. CONSTRUCTION MATERIALS
Introduction
4.2           Clay Materials
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4.3
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J? J         Z.afrtwftf-Lin TiffJP’jk'
5.2.4
£taw Zoning
mu
5.3
54
J*2J         2‘rfter &NT£JT
PERMEABILITY OF Main’ Dam, SajDMjH DAM ABUTMENT AREAS .
53J
4$
4ft
4^
.49
49
50
JO
.....JO
..5/
iiniiiicimri 53
.11 .
5S
LAW sliding
listoftables
Table 2.1                 HORFWI.IiAlLLIND DETAILS
........................................................................ ................................................ 5
table i i
Table 2.3:
Table 2.4
SUMMAS V OF H* U&WGIC LAYERS AT na IJAW AN fl JAC IDLE AXIS tKOM THE DRILLING
DEPTH TO TIC WATER TABU .................................................................................. .................................................... 6
........ ....... 6
DETAILS <1F Ct AV JI.^UICW AREAS
..................................................................... .................................................... J
Table 25:                    E-SFMATED QUAJiTI Ieks W HORRO* ANO QUaMi V MATERIAL
................. _............................. ................9
Table 2.6
T*SU! Il
Lamia™? IsnCONDUCTIO.................................................... ........................................ ............................ _..._............................ ... | ]
GRCUbTWATU HJINTUATA Of THE PROJECT AREA--------------------------------- ----------- ------------- ,...,_................... ........„,.. J«
Tablf ] 2                     VESruirmtAT AJUoDEhtssAiiTE.................................. _........ ...... ............................ ................................................... ................._.4i
Table 3.3:
Summa* Y Of THE VESjijr vs Y ........................... ............................................................................................... ... . 42
Table 5.1                    SLMM.AR Y of CLAY DtSIGN PARAMETERS ______________________________ ______________________ ________ _.... 47
Table 5 2.
SUMMARY Cf ROCK DESIGN PaEamfTERS................................................................................................................. ................... W
TABIC I y                   Location w Clay wmce areas ........................................ _ —.............................................. ............... ....... .. ............... .................jq
Tabu H                  stilctel^DesignFii.rtK bam>... . _
u..i.... .. « m* ■—........................................... ....—52
Table 5 5:                   Sl.TUMA AX QF FALLING H£aP PEJLMEaJi:i JTY TOT RESULT ..................... ...... .......... .................. ........... ............. .............. 54
TaHLE1.6:
Table 5.7.
SUMMARY c* THE LUGEON VALUE .............................................................................. ............................. ...................... 53
SUMMARY UfPEAMFAaiLJTir 1L5T RESULTS FOR BOTH TEST TYPES
...................
ill
Water Works Design & Supervision Enterprise
In Assocl-aLin-ri with la tern I) tin tn Hl Consul Lui Ls ind TetlmtcnU PH LLdArjo Dedessa IrrlgitlM Project
Geological & Geo tee tuilcal Investigations
M*j2W7
LIST OF FIGURES
Fh i«BJ1      Ekjfti3®X 1 I a’MJATIQN MAP — ------------------------------------- - --------------m------- ..hi.i-.-hiii;. Uiiii—IHII-.UI................................................................................................ -.Hi.—;!;.. -.m; ri 4
Figure 2 2
Hl iRROW AREAS t CKAT1DN MAT., .tiniraiiiuwsiuii
inm-
1-1 ; mm i; m. ill ;m- ■!!!■
■      ms- (0
Figure J 1 Geological ma^ui- the dam a-ndresfrwmr area----------------------------------------------- - —---------------------------------------------------- -...20
F(GUR£3.2            CjBDUUOICAI MAPCU THF Dam. SADDLE AKD 5KL! WAY AREA................................................................................... 21
FIGURE 3.1*         GEOLOGICAL lRCSS SECTION OF THE v*AM AXIS ALONG A M Figure 3.4             GEOLOGICAL CROSS S&C i I'jM r.+ 1 i^F fJAM jTTfJ aLONQ Al j i
........ ............. 22
23
FKWM S 3
CjtUtOGHjAl “CRljSSi SFlTTklN DF THE SaD(X«E DaM 3mE =.r .....
c                 1ll]; ;i;, «■■■■
nm :hh24
FCLiRE 3 6           GEOLDGKaLCROSS SECTttJK UF THE SPILLWAY......................... ................................ 23
F«UMl 1 7             STtSfOnbTOf anil HUNlOW^miiN IN rut ALKAUbT BASALT Of RIGHT ABUTMENI [N*35j .... .... 32
Feure J.k.             STEREDKDT OF TIE XJ4VT DflP DiMELTkXM IN DiE aI.kajJNF RaSAJLT C5t LEFT ABUTMENT 1N Wj.. RGUfcB 3 9          STUtEOFLUrOFTHE ICOTT EHR ElDON N THE ALKALINE RaSaLTOF h-HMX E DAM 0
FlGLUE J 10a: JttMWC DIRECTION Of THE A- X.AI. 3NI BASALT A r “HE MJVUt COURSE IN THE RESERVOIR AREA. I N-iU| 15 PTL.il.TCJf. 1 1011 Ii hkiWm WK'WWDf DIE APHANmC BaSaLT (LEFT RESER YcxR]. iHl MAJOft DIP DIRECttW IS N251*AT
33
......... .. 34
AM AVERAGE DIF AMSU OF Jf*C *<0> ________ ____ ——...._______________________ _______________ _________  W
c
FhilrttE  1-  IOC  bflT3lkfiLlli  K4<.Q  JCKNT3TXF  THE  ALKALIK  BaSaL  T  AU  OvFM  rUF  ARtA  I  DAM  SITE  AND  RESERVOIR!  THE
MAM 4XT DIRECTV*! IS Ml I &‘aT Ah' AVERAGE DCF ANGLE OF TZ*(Sr-1 35I
JA
FIGURE 5 1 SAND FILTER DESIGN ...._________________ __________ _______________________  ____ ___ _______________________ „„,S3
LIST OF PL ATES
Plate 1             Mcxpholog*/ o3 tom site iooking d/s
Plate 2            Fraclure condition of Che alkahne basalt as observed in (he river course
Plate 3            Jointed aphanitic basalt exposed an the surface on “he ten side Of i.r e rwer outsito
the reservoir level
Place  4  Alkali  basalt  difce  at  Ketkelo  spring  ctoe  Lo  the  confluence  of  Wama  wrth  Dedessa river
LIST OF APPENDICES
Appendix A Appendix 6 Appendix C Appendix 0 APPENDIX E
Borehole logs
PlKHograpM of ccxe
Field Pe/meabihiy Teit resuiis Test ptli tog sheets 
l*hoh*tc«¥ Tests result
Appendix F           Geophysical survey results
Appfndix G>        Piezometer Insiallatiqh Detail
Waler Works Design & Supcrrislon Enterprise
In Asia cJitlon wlW JnterconiintDULi ComuJtuits uid Tnchnncny; Prt Ltd.
IVAi>D< dess* Jjvlfstlca Prtjed
Ewtogfcai & GEQtwhnfca) Invejtig&tions
LIST OF ABRE VIAT1ONS
ADi                   Ana-Dedcssa BorehoTe one ar dam site AOCAO           Ar^ Dadtissa Coaese Aggregate Quarry s-ile ADQ1               Arjo-DedessJ Borehole one aE rack quarry site ADS1               Aij>Dedeaaa Borehole one ar saddle dam sJe ADSPt              A/jo-Detfessa Borehole ore ar spillway site
AtSTPt
BCEOI/I
Are Borrow area Teat Phone
C                      Cohesion
CD                   Confined droned
CDSCO Construclion Design Share Company
CJhBTPI cmi’31
Chewo Bcxfow area Tesl Pit one Centimetre per second square
CU                   Confined untrained
OhBTPI Dhtndessa Borrow are* Test Pit one
0
K/A/ KrVm3
Gravniahonal Acceleration Potassium Argon
Kilo-Newton per meter cube
LL                     Liquid limit
ffi
metre
M0TP1             Manbo Borrow area Test Pit one
MDD
N13tf
Max Dry Density
130 degrees from north
NE                    North east
MMC                    Natural Moisture content
NW                   North west
Ob6TP!             OtXMiB Borrow area Test Pd one Ohm-m             Ohm meter
OMC                 Optimum moisture content
PI
Plasticity index
PL                        Plastic limit
SE                    South east
SSD                  Soaked dry sand
SSWIN              SpftenStat for Windows
SW                       South west
Water Works Design i Supervision Enterprise
In AilUcilUon wl(i lultrnnUneiilil CotwaHui Li tnd TetluitcrtU Plrt. tHLAr jo Dedessa Irrigation Project
Geological & Geotechnical InvesUgattous
ucs
Unco*tfu*ed compressive sltenglh
USBR
United Slates Bureau of Reclamahon
UTM
Universal Transverse Mfrreaniile
uu
Untra ned unconfmed
VES WAPCOS WWDSE
Vertical Electrical Sounding
Waler Works Des:-gn and Supervision Enterprise
XRD
X-Ray Diffraction
Water Works De a I go & Supervision Enterprise
Id Auodtuaq Tita tuttmeUDtoul Gooavlcuiu ujdTechDflcrits Prt HiArjp-Dedessa IrrlgillM Project
Geological & Geotechnical InvBSllgatLpns
May 2007
1.
Introducti
on
Thit
report  relates 
to
the  gEofo
gHial
and
geotec
hni
cal
investigations  co
nducted
in
relation
to
feasfi
ihly  study  of
Arj
o-Dedessa
irrigat
ion
project.
Il
als
o  discusses  the
interpret
ativ
e  Dart
on
some aspects of (he study
The Afjo-Oedessa irngatkm project development consists of
■   Main dam
■   Saddle dam adjacent to the main dam
•    Primary Canals running on lhe left and right banks of Dedessa Rirer towards 1he command area
*    13665 ha irngaLed area
The Report has been organized in the following manner
tntfodudjon Investigation
Secton  1  provides  the  Mtroduction.  It  inuoduces  the protect component
Section  2  outlines  the  investigation  methodology  and scope ol lhe field investigation worts conducted
Regional Geology         Section   3   drscusses   the   Regional   geology   of   lhe project area
Constructor! Materials
Seclion 4 presents  resuhs  of the various  construction materials  investigated and studied for use in the dam section and elsewhere during implementation of the project.
Geo4echnical Design Consldeuaton
Secton      5      derails      the      geotechnical      design considerations in the design of the dam
The Appendices  contain supporting documents  as  follows  Borehole logs  (Appendix  A> Geophysical invesligaton Results  (Appendix  F); Field Permeability  test Results  (Appendix  C); Photographs of cores (Appendix B): Test pus tog sheets (Appendix D), Laboratory test resulls summary  and interpretative charts  (Appendix  E); and Piezometer installation details  (Appendix G}-
1
Water Works Dcalgn & SuporrUlon EoterprUe
Ln Assortadtm with lalertguUnmal Consultants and TreJinc ersts Pvt. Ltd.)
]
■B rfi i .'T           11 iflMlArjp Detlessa Jrri?*ikin Project
Geological & Geotechnical Investigations
2.    Investigations
2.1  General
May 2007
The aim of the  field mvestigations was 10 address all Issues necessary to present the technical
and  econqmtcal  feasibility  of  the  proposed  structures  with  sufficient  revel  di  ilWMlljallCin*.  At
lhe  beginning  alt  relevant  information  found  from  previous  studies  of  the  project  area  was 
reviewed and analyzed
Ba^ed  on  rhe  avaifabfe  information  ground  conditions  characterization  program  W5  developed
giving  allent-on  Io  how  the  various  conslruction  parts  are  affected  by  the  character  of  1he
ground  Consequently.  major  proWems.  were  defined  and  the  gap  of  information  related  10
feasibly of me project structures was identified and acted upon
Rolary  core  drillings  was  used  for  investigation  al  the  dam  sue.  saddle  dam  sites  and  quarry 
sites.  The  drilling  program  was  constantly  reviewed  during  the  field  work  and  revised  in  order
Io  gel  optimum  result  from  the  drillings  The  final  program,  including  adjustment  ba  sod  on
continuous  evaluation of results obtained during drilling is shown on Ta ole 2.1. The Rotary core
drifting work was conducted by the Construction Design Share Company (COSCO).
Vertical  electrical  sounding  work  was  sub  contracted  to  Ethiopian  Institute  of  Geological  Survey 
by  the  contractor;  COSCO  The  a-m  of  this  geophysics  survey  was  to  get  additional  information
■n  between  the  exploratory  boreholes  along  the  dam  axis,  saddle  dam  axes  and  (he  spillway 
area   A   total   of   10   vertical   electrical   sounding   (VES)   were   conducted   along   the   above
mentioned profiles.
2.2    Previous investigation in the area
The project site had earlier Deen studied by the USSR (1958-64) as pan of the Land and Water
Resources  Study  of  (he  Blue  Nile  Basm.  by  WAPCOS  (1989  -90)  as  part  of  (he  Preliminary 
Water  Resources  DevekipmenC  Masta  Plan  of  Ethiopia  and  by  BCEOM  (1989)  as  part  of  the
Abbay River Basin Inlegrated Unvelopmenl Master Plan Project
A  detailed  review  of  the  previous  worfcs  had  earlier  been  reported  in  the  Inception  report  All'
(he   above   studM   were   general   des*   sludms   and   did   nc(  include   investigation!   consisting    f
a
drilling,  mapping  or  laboratory  testing  The  cufrenl  dam  site  investigated  is  a  new  site  proposed
by WWDSE So no previous investigation had been conducted al this site.
2
Water Works Design & Supervision Enterprise
In AsiDdaUan with IcCtrwntlnflnukJ Cflnsnlumu ud TtthnocrMa Pvt Ltd.ArjoDedMsa IntfstiiM Project
Geological & Geotechnical Investigations
2.3 Objectives of the present study
The obicctwes of the geotechnical and geology investigations conducted are
*    I u Study subsurface corMditions at major structure sites including the dam site
•    Identify suitable construction materials for use in the proposed dam
■   Study the property of the construction malerials
•    Assess founoation permeabihty properties
*    Identify ihe geology of the project site at feasibility revel
■   Prepare preliminary design Jewel to engtte 10 conduct IM feasibility of 1he project
2.4 Methodology
The methodology followed for geoJogical and geotechnical investigations were as follows:
*    Geological mapping of the dam sue including the dam axis *    Borehole drilling at dam site spillway and quarry sites
May 20OT
*    Permeability testing within the boreholes for lhe dam site and installation of piezometers *    Cieophysicai Investigation to augmanl the Dore drilling works
■ Test pilling at construction material borrow areas and sampling
*    Laboratory tesling of samples collected from boreholes and lest pits
2J        Geological mapping
Geological mapping of reservoir area has  been done making use of aerial photograph topography  maps  and field work. Outcrops  nt rocks  were mapped along with joint orientations spring areas etc. Details of the mapping conducted are reported under section 3
2.6 Borehole drilling
2.6.1 Location of Borehole
12 boreholes were dulled wrth a total depth of aG5m Out of lhe 12 boreholes 7 were dnibed along the dam axis fNamed AD1 to AD7), 1 at spillway (ADSpl), 2 at rock quarry sites (ADQ1 >nd ADQ2) and two afong the saddle dam (ADS i and ADS2). Except two holes drilled along the dam axis at 60° to Ihe horiiontal, the remaining ooreholes  were vertical Drilling depth varied between 3m to 92m The borehote locabon map is presented in Figure 2.1 and details are available in Table 2 1
___ 3
Water Works Design & Suppnlslon Enterprise
In AssodatloB With lnltrrandnepm Ceoiultants tad Tedmocmts Fn Ltd.MK»H
QOflHHB
UfiGH
ilWEbF.
DDffilb-B
£OOi»B
OoSCrrE
MAP SHOWING DR LL HOLE LOCATION
L±GEH*>
M*n a «■<
contour
SOLE
i-
2.1 Borrhcle Location Mi
*TlONSAT ARXI        ’jEOGSSA irrigation project dam and saooi
IT.
244000
244
z«awn
FiOur« 2.1
Loc *,k>nArjemede ssa Irrtgitlon Project Geological & Geotechnical Ingestigaiions
_
MayjOO?
Depth 10 bedrock  and ground water table, variation in nock  type [litho tagy] degree of weatnerrng and fracturing of the rock mass and rhe tike are the information collected from the cores of exploratory drillings and the boreholes. DelaiJs information is shown in lhe borehole logs included in rhe report from the dnJHng contractor under Appe/vdix A.
Table 2.1 B<iftholt drilling tetirii
Ho.
Miin Dim
Axil
Ai5rf
AD-2
AD-3
A£M
]|
Elttin®
|UTM|
243055 243096 243147 243198
N&rthlng
IUTMI
EIh-v.
Orientation
|GP5            in dag From
reading^
H'fl-r.
Onentadan
[dtg.J
Dnlftd
(mJ
Permeability
t4»t*
cDnductnd
'9*52*4 1360m 90
9422$!?            l34Cm              50
&4236S           1320m             60
9424M            1322m             90
■a
33 30
«
7
7
0*5
92
50
41.70
15
-
9
AD-4
243305         942643            1365m           L».
7
AD-e
243605          942809            1355m             60
000
30
«
W"                    243073         942365            1342m             90
-
29.10            4
Spillway
w                242550
941740
1379m
M
T
24.20             1
Owmti
ADqd 242190
943103
1357m
90
-
15                 0
____
2*3582          934498            1447m
M
-
3
0
Siddhe
0*m
AjDS-1       2442(50 ADS-2            244
942S50
1350m
90
■
24.60
4
942500
90
22.20
Tolll
1
4084
61
ZrG.2 Drilling Results
The subsurface geology of the site was determined from the core drilltng and tests pitting The drilling  tog  shows  targe  variations  both  in  fraclunng  and  weathering.  The  left  abutment  fs  not only sirongly fractured but also highly weathered On the ocher hand, the weathering of the right abutment   is   moderate   as   compared   to   the   left   abutment   The   river   course   area   was investigated  with  the  help  of  an  inclined  borehole  AD3  and  this  showed  relatively  strong  rock with   moderate   fraclunng   The   subsurface   geology   of   the   saddle   site   is   characterized   by fractured  rock  at  ine  middle  of  lhe  saddle  land  2  and  Hood pla-in deposits at the depressions where  ADSland  A.DS2  were  drilled  Summary  of the upper layers of the dam and saddfe sites as reconstructed from the drying result is depicted In Table 2.2
5
Water Works Design & Supervision Enterprise
Ja Ajssortatlo-d with litteres nUAnntaJ Consiilumcs ud Techaocnts m Lid.Arjfo-DedEssa. Irrigation Project Ceologtcal&Geotectmlc&IIavestigallOns
__________  ^_May2M7_
Table 2.Z: Summit *f th* ga^fll* ****** at Ch* *nd saddle axis from the drifting
Laytr and
tocttfcw
Ttikckniti
(m|
Formation
Remirk
r  ?;e
Fr^clunnotoe altering
1 (livar binfcil
d5
Sandy, ally day
Aauvium
i.Dc-te malarial
2 {left afei£mi?fm
About*
&avt*T sandy ttyer
Cc«jviufn&
Hatflrogfineous rralenad
3 (lift abufcmeflh
About 25 m
Iratfiy
Spangly       fractured       ard h-ijbiy weathered
Through  aUl  Iho drying depth
■3 [rive* cnurse}
w-io
Traehy basalt
Highly       ID rnqdpralely fradured     and     weathered fr&Chy basjll
Strong material
4 fiver cwiriei
> 15
Trathyia
Fraah oui
Strpns
5 fi^lM aOUliiwrtl|
>20
Alkaline basal-fiyhowia
Modwalfly            weathered and fractured
Slrixig
IlMEkflfl
0-5
Say day
Flood p£ain deposit
soft
r 2 i.&addle.
7-17
TracJlyhC ryixalile
Decornpcs-id
|3 (saddle)
About 5
Wkahne basalt
Moderately         vrtaihered. iracxuued
--------—------- ---------
2-6.3 Permeability testing
In silo permeability of lhe vanous rock formatK?n$ has been determined by the use of Packer tests and falling head method m the section of the boreholes Test sections have been confined by  use of single packer in the boreholes  The total number of permeability  lests  conducted in borehofes  was  in the order of 61 Piezometers  AD4 and AD7 were nstalled in two of the borehole's for observation of ground water fluctuations.
Table 2 3 shows the revel of groundwater observed dunng doling. Titre 2.3 Depth tq the water table
Borehole
Eteva(ion(m]
Depth to water table, m
minimum
AD-1
Maximum
Elevation
1360
ni
29
AD-2
1340
195
10.3
1320.5
AD-3
1320
5,7
52
1314.3
AD-4
1322
2 OS
1 80
1319 95
AjD-5
1355
mH
Mill
-
AD-6
1355
mil
Hill
-
AD-7
1342
19 65
10 2
1322.3
ADj-1
1350
17
14 05
1333
ADs-2
mil
Mill
■
ADsp                          1379
mil
Hill
The results Of lhe permeab^fy tests conducted am provided under Appendix C
Water Works Design & Superrislou Enterprise
Ln AsMdadau wlte IntertonUfientaJ Couullanu and Tectmocrau Pvt Hi
L■.
6ftrjo Dedeasa Irrijatlfla Projtec
GBflloEfgilfcGcDl
eehnical Inyestlgatlons
MayEW^
2A4 Test pitting a
nd sampling
Test pits were ex
cavated at borrow areas 
Io decemine
depth of suitable material! available and
to  evaluate  their
engineering  property  by 
comducling
laboratory  tests  from  samples  collected
Test pls were excavated along spillway axis to determine depth to bed rock. The location of the borrow areas where the test pits were excavated is provided in Figure 2.2 The total number ol tests  pits  manually  excavated in 5 designated clay  borrow areas  was  53 Besides  the lesL pits excavated m clay  bo/row areas  5 tests  pits  were excavated in sand quarry  areas  to determine extent of sand availability  and to assist in collection of samples  Details  of lesl pits  excavated are provided under Appendix  A Table 2 4 shows  the details  of test pits  excavated wilhin the designaled borrow areas  And Table 2.5 the quantities  available at these borrow a^eas  and quarry sites
Titlf 1.4! Detai ls-gP day borrow arv-jt
l
1
No,
-f-—1
Reference
Location
Easting
Northing
Excavated
Depth fmj
1
AtBTPl
ATE
244382
935180
1 10
2
AtBTP2
ate
244344
935313
1 10
3
AI0TP3
ATE
244256
935489
230
4
A1BTP4
ATE
244395
935587
080
5
-
AtBTPS
ATE
244476
935478
1 10
6
ALBTP&
ATE
244521
935350
240
7
AtBTP?
ATE
244545
935192
290
a
AtBTPB
ATE
244156
935280
1 00
&
A10TP9
ATE
244005
935329
1.40
w
AiSTPlQ
AlSTPlt
ATE
-
244030
935205
1 35
11
ATE
242700
933750
1.60
12
Ataipu
ATE
24MW
933866
2 10
13
AtBTf 14
ATE
242329
933554
1.20
14
AtBTPlS
ATE
244775
935295
315
15
A10TP17
ATE
245U3
935500
1 50
16
ChGTPi
CHEWO
244204
936980
090
17
CMTPJ
CHEWO
244014
938895
t 15
ie
ChBTPJ
CHEWO
243815
938862
2 ib
to
ChBTP4
CHEWO
243614
L
933802
335
Water Works Design t Supervision Enterprise
hi AMOdaaOD with Intert®otinentij ConssItsbLs sad Teetamntl Pn Lid.Arjo Dedessa Irrigation Project
Geological & Geotechnical Investigations 2.6.4 Test pitting and sampling
May 2W
-
Test pits were excavated at borrow areas Io determine depth of suitable material available and to evaluate the-r engineering property  by  conducting laboratory  tests  from samples  collected Test pits were excavated along spillway axis to detenu ine depth to bed rock. The location of the borrow areas where the test p<ls were excavated is provided in Figure 2.2. The total number of tests  pits  manually  excavated m 5 designated day  barrow areas  was  53 Besides  the test pits excavated in day  borrow areas  5 tests  pits  were excavated in sand quarry  areas  lo determine extent of sand availability  and to assist in collection of samples  Details  of test oils  excavated are prowded under Appendix  A Table 2 4 shows  the details  o! lest p-ts  excavated within the designated borrow areas  And Tabte 2.5 the quantities  available al these borrow areas  and qusrry sites.
Tibl» 2.4:             OetlUl Of clip bwmw imt
Ho.
Reference
Location
Easting
Horthlng
Ejteavatad
Depth fm)
1
AI0TP1
ATE
244382
935100
1 10
2
A1BTP2
ATE
244344
935313
1 10
3
AtBTP3
ATE
244256
935409
2 30
4
AUBTP4
ATE
244395
935567
0 00
5
AlflTPS
ATE
244476
935470
1 IQ
6
AIBTP6
ATE
244521
935350
2.40
7
A10TP7
ATE
244545
935192
2 90
&
AfBTPe
ATE
244155
935260
1 00
9
AIBTP9
ATE
244005
935329
1 40
10
AtBTPIO
■i ■■■ ■"        ™—
ATE
244030
935205
1.35
ii
AtBTPlI
ATE
242700
933750
1.60
12
AIBTP12
ATE
242605
933866
2.10
13
A1BTP14
ATE
242329
933554
1 20
14
AIBTP16
ATE
244T75
935295
3 15
15
A!6TP17
ATE
245133
93550Q
1 50
16
ChBTPI
CHEWO ----- 1
244204
936900
0 90
17
CftBTPS
CHEWO --- ii rr
244014
935695
1 15
ia
ChBTP3
CHEWO
243615
936662
2 10
19
ChBTP4
CHEWO
243014
933802
3 25
Water Works Design & Supervision Enterprise
In AiMJriidcD rich InterauttaeoUI Cattsvltifits and Technocrat Pvt Ltd.Arjfl-Dedessa Irrigation Project Gfr&fogleal & Geotechnical [nwescigatlors
May 200?
~20 ■
CKBTP5
Chewo
| 243555
938642
1 85
21
ChfiTPS
CrtEWO
243751
93B658
1 90
22
ChBTP7
CHE V/0
243840
930755
0.90
23
O6TP8
CHgWO
243960
938820
1.80
' 24
ChBTP9
CHEWO
243448
L
930792
3 00
i-
‘ dSbtpi
DHENDESSA
249564
339460
2 10
26
DhBTP2
DHENDESSA
249515
939663
1.50
27
D46TP3
DHENDESSA
24^476
939850
T 75
28
DhBTP4
DHENDESSA
249554
940026
1 90
29
DhfiTPS
DHENDESSA
249726
940139
3 25
30
DhBTPS
DHENDESSA
249B59
939994
1 90
31
DhBTP?
OHENOESSA
249884
910714
1 90
32
Dh6m
DHENDESSA
249936
939531
1 OG
33
PhBTP9
DHENDESSA 2+9868
939307
145
34
DhSTPiO
DHENDESSA
249344
939493
2 60
35
DhBTPll
DHENDESSA
249245
939670
2 10
36
DiifiTPl2
DHENDESSA
24915$
$39488
1 75
37
MBTPI
MARIK?
250341
933153
1 70
30
L.
____
30
MBTP2
MAR ISO
250538
93S172
1 45
MSTP3
MARIBO
250547
938043
1 50
40
MBTP4
MARIBO
250413
937951
1.70
41
M8TP5
MARIBO
250269
937970
2.40
42
MBTPG
maribo
250190
937940
0,70
43
MBTP7
MARIBO
2500®
937912
a 30
44
M6TP8
MARIBO
250002
930057
210
45
MBTP9
MARIBO
2S0154
935204
2.70
46
MBTPiO
MARIBO
250271
938227
2.20
47
ObBTPl
OSSE
244690
946171
2 30
46
Ot£lTP2
OBSE
244805
9+6299
1 60
49
ObBTPS
=---------------------                        3
OBSE
■
244684
946397
1.70
__________________  B
Water Works Design 4 Supervision Enterprise
tn Association with iHtmoatlneotil Consutl&nU ind Technocrats Pit Ltd.Arjo Dedtssa lrrlE>Uan Frucci Ge uC-og’Icat 4 Gaotacliiilcai [pfastlgadons
May 2007
TiH# 2-5:             Ettlmafed Qu«n1i1m* al B crrow
Item
no
Site ruffle
I Estimated
3
Volume (m )
Distance from
dam
sltelkm)
Location
Easting
Northing
Type/narne  of  the malerial
Cray.foj core
11
|A1e
31.541.56
8
244000
935329
Silty clay
2
Chewt
345.32750
5
243550
936640
Sfljf day
3
Maribo
502 603 13
10
250000
937910
Silty clay
4
Dhendnssa
S .062455 00
6
249725
940140
6
Obae
140.567 50
4
244805
946300
Silty day
Silty day
Sum
2.082.494 79
■
Aggregate
1
ADCAQ
>1.000.000
—
243582
934696
1
Maribo
>1 oco.ooo
2
247500
942350
Basal
>2.000,000
Shall material
1
AOQi
>6624000
1
242190
943100
Trachy basalt
2
Guche
>3.000.000
12
234489
943400
Burt
>9.642.000
Riprap
1
Bukeia
180.000
6
249320
941079
Phonohte/T r^chyte
2
CcHisin
120,000
26
224180
946815
PhrjflflditeTrrachiffle
300.000
Sand
1
BOrCJlt
800
f
GO
214802
959157
*
2
Lo*o severs
700
w
211860
960600
-
3
Lokc bndge
500
so
215289
961337
-
4
Tuflu sen&tle
L
«
65
1
-
■
MH t Sfirrtaltd
5 NQt
m wtn seasons
9
Water Works Design & Supervision Enterprise
In Assflctatlon with luUmMlnentaJ Consultants and Technocrats PTt. Ltd,borrow areas of clay and quarry     sites for shell material, coarse aggf&gat® and riprap materials
233000
2*0000
242000
244000
24*000
2*KOO
250000
252000
2SW00
A
LEGEND
* Bcrehole locar»on
Quwr- area
f
Shell maternal! Quarry Clary core borrow area Riprap Quarry tilt Main River
ScOndary R'i-e* Dam tj«i$
SCALE
r 53000
4faii*rA
Fig<»e 2.2 fiorraw areas U»< -rf"511 ,n*
238000
240000
242000
244000
J44M0
24MOO
250000
252000 J 54000I
■I
ArJdDedesia ErrtEitkin Project
GfrologlcaL & Geotechnical Investigations
2.6.5 Laboratory testing
MayZODT
Soil  testing  has  been  ca/ried  oul  at  CDSCo  fatwatery  to  determane  engineering  properly  or various materials on samples collected from
*    Foundation areas
•    Impervious Clay material
•    Sand Fitter material
♦   Rock samples
♦   Aggregate samples
The  laboratory  tesls  conducted  are  shown  in  Table  2.6  and  details  of  results  are  available  in Annex 5.
Ta fate 2.fi LatKJfitory tMte CanducBtO
Type oT cm
Number
XRD
5
Standard pr cd w Compaction
2S
Aflerbrg L.mitt
52
TriflUi^H
UU.1D.CU 5. CD 2
Pfimeablhy
4
DiSperjijyi (p^ hide)
20
Fra* Swell
25
Grain Size Analysis
27
Specific Gravity
25
CoHMMtdbn
Shrwikage Lamd
5
I
10
Neural Moisture ccnlem
43
11
Water Works Mfc* 1 Supervision Enterprise
In AiMdailen wllli iBtertontlMntel Comultuti and TwKnocnt! m Ud.Aijo Dedeasa Irrigation Project
Geological & GeotecImlcaUbvestigatioiis
May 2007
3. Geological investigation
3.1    Regional Geology
The geology of the valley is mapped as metamorphic rock m the Geological Map of Ethiopia. 1996 by ElGS However, field observation and regional correlation show that apart From th* metamorphic rocks. volcanic  rocks  have also covered the project area Accordingly  from field observation and corretabon with 1he geological map of Ethiopia IM regional geology of the area under consideration is frnefry descnfced in the following paragraphs
3.1.1 Metamorphic Rock
Field observation of the metamorphic rock was made along the road rrem Beaele to Arjo and
towards the dam site through the dry weather read along the right canal route Granitic hills and
boulders were also observed along the right mam canal route
According Io IM geological map Ethiopia by Tefora *t al. 1996, the metamorphic rock of the project arc* is  the Alghe Group This  group cl roc* consists  of grey  gneiss  with variable colour mdex Showing development ol layenng Much oi this  unit is  relatively  uniform and poorly  layered orthogenesis, representing deformed and metamorphosed plutonic  rocks  of diorife and quartz diorite and fonoMc com position
3 J. 2      Tertiary Vol ca n Ic roc k $
3.1.2.1   Jimmi Volcanics
As  cried in the explanaiicn bulletin of Geological map or Ethiopia. 1396 lhe volcanic  rocks  are analogous  Io the Mam Volcanic  Sequence of Davidson 19B3 They  form a thick  succession of basa ls  and felsic  rocks  with basalts  dominating the lower part of the volcanic  Dav*dson has reported K/Ar age of 42 7 1o 30.5 Ma for the Jima volcanic These Jima volcanics form lhe base of the reservoir and extend in the upstream direcban of lhe nver basm
3-1.2-2    Mekonen Basalt
Tnese are thick sub-honzonlai flood basalt mapped by Davdson 1933 The Mekonen basalt mostly directly overlay the basement complex in lhe southwestern plateau and are dated K/Ar age of 34 8 to 23.1 Ma | late Of^occne-early Miocene) The Mekonen Basalts are considered analogous to lhe Wotega Basalts, which a- e outcropping m Wotega area
r
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Geological & Goo technical Investigations
3-1.2.3 Quaternary plateau basalts
Hay 2007
These bauRS Outcrop malnry al me dam site area They are strongly fractured and wealhered as observed in the field These Quaternary  aixa ne basalts  and trachytes  were erupted atong pre existing structures  The area is  characterized by  NE-SW trending major lineaments  whtch are observed on Ehe satellite imagery The eruption of these localized alkaline basalts and trachytes is expected through these major fissure directions. The rocks are believed to be Pleistocene m age
3u2 Arjo-Dedessa Project Area
3.2.1 General
According to lhe field observation the geoTOgy of the project area can be described by crystalline rocks (igneous and metamorphic) which are covered by alluviar and colluvial deposits. teSidua^
sols and flood p*ain deposits Upstream side of lhe command area and lhe reservoir area are
covered by both volcanic at the lop and metamorphic rock at the bottom under the soil cover
Votesnic rocks cover the abutment of the Dedessa valley while going dose to the valley bottom downstream or the Dedessa-Wama Junction the metamorph c rock is Outcropping
The escarpments Crf the valley m the upstream area from the dam axis are Jma volcanics and on both escarpments  downstream of lhe dam site is  Makgnen basalt. The mapor volcanc  piles  are cropping oul at the escarpments and are observed on the plateau and escarpments of lhe Dedessa valley At lhe valley bottom where the dam sde is located the alkalme-lrachy-basall rock outcrops and forms  ridges  and abutments  Moving further upstream following the ftve* course is  aphanitic basalt which can be associated to the flood basalt of Jima Vo*c*n»c$ The geological map of the dam and reservoir site is depicted m Figure 3 1
Therefore the general stratigraphy of lhe valley can be summarized as follows
*    CoRuvkabAlluvial - F lood plain sediments.
*    Aikahne-’irachy basaivyquaternary plateau basalts *    Aphanitic OasalVjima volcanos
*    Metamorphic rock/AJghe Group
13
Water Works Design & Supervision Enterprise
[n MJOCtadOD wtLh Intercontinental CoosultiriLs tod Tethndcrals Pvt Ltd.Arjo Dedessa Irrigation Project
Geological & Geotechnical Investigations
3,3     Dam Site Geology
3.3.1   General
May 2007
Two rAla'rvefy atop abutments bounding Flat River /alley which is situated CkHC tq the fool ol lhC ;eh abutment. Chmdwtee the morphology ui the dam sue Alkaline verbca? dikes al the ifcpe and tap of Che ndgcs Of ihe abutment gdvfl Che landftxm U> bo iteepC' The shape of the dam iMfr lacing down stream is as shown in p?ate 1
Plate 1 The morphology of the dam me looking dawnscream
3.3.2  Dam Axis Geology
According  to  the  fieM  observation  and  subsume  mvesbga'ion  resuds  stratigraphy  of  lhe  dam  sice am is composed or
•    Alluvial deposit
•     Colluvial soils
■* Strongly fractured a-’d weathered vesicular alKahne baRalt ryhcfite and trachyte
13,2.1 Alluvial deposits
The alluvials  are deposited along the riverbank  ano are abaul 3 !t> 5 m thick  above 1he alkalme^achy. basalt dose to th> dam site area and above the aphannic  basalt in (he upstream areas of lhe reservoa. The soil is loose. Orownuh Ip reddish in colour composed predominantly of
Water Works Destgri & Supervision Enterprise
in fcsnnJadrirt with lott motlaeattl Coosultiau ind Tsehimeri ti Pvt LtdAfJoUcdesai Jrrlgadcin Pro] act
GeolDglcal & Geotechnical In vesLlg'atioias
Hay 2007
hnc sand and eft with rHinor graved. Tha average Wckrwss of the soil at the dam srie as measured from [he exposure at the riverbanks rs aboul 5 m. The tfr^m^g at the exploratory boreholes ADJ a"d AD4 recovered cores of alluvisl material Io range from 3 8 m Io 4 B m thick
3.3.2.2        Colluvial soils
Th*it serfs are wth minor transportation from tnejr place of format-on The sligh! rnuvornem across lhe slope i$ due to gravity Colluvial soils are available at slopes of the left a&frlment and at the laolnill of the right abutment The colluvial soils of lhe left abulmenl cover sites where ADi, AD2 and AD? were dr - ed The ngiht abutment however has no cCiluwai cover at me dam axis al its lower stope side At the right abutment the co'iuv-ai toils are off the dam axis and occur on boflh sides of lhe dam axis. The sods are mixed’ ranging m gram size from clayey to boulders with no Strauricaba*i or horizons. The visual obscrva-lion and mterprclatign of lhe drilling resuK showed that lhe average thickness of this coltuvium along She dam axis ranges from 07 al ADI. 4.5 m at AD2 and  1  5  al  ADS  However,  due  Io  the  scanty  of  the  structure  of  cdluviai  soils  with  strongly weathered  aftllfte/traohy  basalt  it  is  hardly  possible  to  make  cto-sr  disbncfion  between  the coHurvium a^id the dsccmppged rock from the core samples
3.3.2.3       Alka line/trachy-Basalt
This rook unit is forming 1he abutments and remnant hills both in the upstream and downstream area  of lhe dam sits  The  rock as vesicular al the foothill area and is massive towards up slope The  vesicles  are  partly  filled  with  while  predprlaBS,  hence  are  amygdalodal  and  partly  free from   in-fillings   The   rock   is   strongly   fractured   ai   the   left   abulmenl   ar«a   as   compared   io moderate  fracturing  al  the  right  abutment,  The  fraduras  are  closely  spaced  m  the  left  abutment and  widely  spaced  and  closed  in  the  right  abutment.  Moving  farther  upwards  to  the  top  of  lhe hill    ryholilic    rocks-   in   composition   predominate   especially   in   the   right   abutment.   The petrographic  analysis  of  this  rock  unit  from  sample  of  boreholes  at  different  depths  described the  rock  as  weathered  amygdat&idal  basalt.  Andesite,  trachyte.  No  exploratory  borehole  has penetrated  this  alkalineftrachy  basalt-  tr&ehyte-ryhoide-’  denies  al  the  dam  srte  Therefore,  lhe total  thickness  is  not  known  The  strongly  fractured  and  highly  weathered  upper  pad  gf  the  rock series  reaches  to  a  depth  of  30  m  at  AD3  below  which  strong.  relatively  fresh  trachyte  was encountered  Boreholes  AO1  (33  m)  and  AD2  (40  m)  which  are  on  the  left  abutment  and aligned  along  (he  dam  axis.  ended  within  the  upper  strongly  fractured  and  weathered  ione  of the  volcanic  rock  series.  The  thickness  of  the  weathered  zone  al  AD4  and  ADS  aligned  along the dam axis on the right abutment is 0 and 1.5 m, respedhvefy
15
Witef Works Design & SuperrLslon Enterprise
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Geological & Geatechnlcsi iHVJstJgJLttons^ _
3.4   Geology of the Abutments
3.4.1  Right abutment
iHyao7_
The nghc atutmeni is ctwwKteriifti alkuhiT* b«aB »th -widely MUHd jom*& The alkaline t»»ll greatly  grades  (0  ryholibc  rotk  Itwards  tM  top  oi  1he  hill  Th*ffi   u  only  a  mhor  oulcrop  d vessUar basill at lh& slope of lhe AHI According Io the ewzavation for acc«» 1o 1he drill s4bS, the boliom part lhe abi/lment H nWfrelp fractured and a weathered IraChy MSflir The generalized stratigraphy of the nght abutment Is
• Colluvia* deposes
« Missive attaline basail-CraChyle -ryholi le
■ Frac-lured and vesicular alkaline basalt;
The ccfcviunn is relabvsly thick facing the saddle site and downstream of the abutmenl The weathering degree is high on the saddle Side and relalwefy fresh outcrops are tou^d «l the dam axis and towards lhe top of the hill Traversing uphill foDowhg the dam ax>s shows massive alkaline basalt-jr*^1e-7holrte senes The bottom and eastern face of the abutment *s relatively fractured vesicular ba$aii
3.4.2  Left Abutment
Unlike lhe right abutment lhe rock of left abutment is strongly fractured with closely spaced joints and is stronjly weathered especially at the foothill. The rock type -s mare of
alkaline basalt at the bottom and slopes of die hill with White precipitates in-filled and grades Io ryholnic rock a1 the cap The general stratigraphy of lhe lett abutment can be shown as
* Colluvium
■   Decomposed alkaline basalt
■    Fractured and moderately weathered alkaline basaiHrachyte
The slope and the foolhill area are covered with colluviums above the decomposed basalt. The top of lhe hil is composed of fractured but fresh alkaline basalt-ryolile rocks Aphan-rtc baaal! was encountered at borehole A07 of the left abutmemt, which was drHtd off the dam axis on ths downstream side. This rod? is interpreted Io be basatbc Sill wdhin the alkaline basalt
16
Water Works Design & Supervision Enterprise
In Idsoclittea with EnterMotlnienuLl Consultants and Tecbno-crats Ptl LettArJ&'DEdttSa imffittan PrtjtCl Geological & Ceo[< ctmi c al JpvestlgaiIo
3.5   Valley Bottom
May 2007
The Vilty tHJtiom is (M rivw wwj  i<=erff and 1he f'ai lying plain *here rhe finer changes I(s covise wuh lime. The over COLKW is about 60 wde. which Wtt putty covered wHl WBfcr and partly showing gjk aline bault outcrops during 1he fetd IrtVMtigitai m Aprri 2006 The rock at ttw rtw course close CO (he dem Site recks dark on surface owing to weatherinp 6u11he non- evposed part of (he fMk is pnkrSh - greyish Co reddish Drown when sampled ThlJ rock a1 ih& river course due co the dam Si1e IS alkalme-lrachy bualr end fradmed. The fracture spacing is wide and the fractune’s are closed ones
The vah’ey bottom on both .sides of the rivsf course is about t50 wide at the dam site and wider upstream of the dam site Alluvial deposits cover Uhis pari of the valley bottom The stratigraphy of the valley bottom is
■   Alluvial deposits
■   Afkaline-trachy- basalt
AllWial deposits of the rtvar valley a-re as described above under |h& stratigraphy of the dam am seoFogy  The alkaline basalt observed at (he surface is  pinkish, vesicular and partly amygdalordat The drilling however showed inlemiixed rock of alkaline- traohytie - ryholrtrc in composition. The core sample of (his rock shows fracturing and precipitates of caJcite and dark mr<>erars indrcabng the movemenl of groundwater undernealh The geological1 map and cross- section of the dam axis is depicted In Figures 3.2 and 3.3. respectively.
3.6    Geology of the Saddle Dam site
Two saddle dams designated as ADS a and ADS2 are proposed on the righl side of the nght abutment The area on the right side of the right abutment is undulating gerdly There is one small hil between lhe two saddles The saddles  wifi be closed from lhe fight abutment lo lhe middle small hill as one Segment of the saddle dam and another one from lhe right side of the smal hill to 1he main Mariko hill.
The surface of the saddle is covered by WackP soft, s4y day soit, which is mapped as flood plain deposrt of about 3 m thickness at saddle 1 and only veneer cover al saddle 2 above Ehe trychtec. ryohSic-alkaftine basalt series Closer to lhe right abutment is colluvial malerial and at lhe middle is fractured alkaline rock outcrop. Therefore, lhe slraligraphy of the saddle dam site is as follows
_____________________________ ____________________________  17
Water Works Dcslg-n & Supervision Enterprise
In Association wim hiterccDUneaud Caojuttaiitj and Technocrats Ptc Ltd.AlJr»Drdrwa IrriglLtoa FTOJSCt ErCDiDg'IC'H I & {rfotfflmJcai Investlgad pits
Ccxrwiai -Residual sorts
Flood plam deposds
Trachyte-RhypIrlfrAlkaline basalt 3 6.1 C Oil’Ll v lal-Restdual so I Is
Mar 2OT7
The  wllmrjal  soirs  a!  this  site  ate:  sunrtBr  to  lhos#  al  [he  dim  sue  and  elsewhere  in  lhe abolman!.  They  are  brownish  and  composed  ol  day.  srt|.  sand,  gravel  and  pebtJas  and boulders The collwral soils occur close 1&1he mn Qi the rtgm abutmenl TJ»a drill, ng at A0$*T ADS-2 did n&l encoiteler 1he coNuviaF soils as the dnHihg Sites WWC on the depression areas where flood plain secfimenls predominate According to 1he visual observation the thickness of this Sdf Close to me right abutment are expected to be not more 1han 4 m Mdvihfl towards Wama along 1he centre of lhe right saddle a faddish (0 brownish day SM WM observed in the field. These sods are mapped as residual soils as shewn on the geologies! map <jf tee dam and saddle sites (Fig.3-2). These residual SdiIs are off the saddle axis
3.6.2 Flood Plain Deposits
Flood plain deposes cover the am ai lhe depressed Sites Of lhe saddle dam sites ThesE are composed of mainly clay with silts ano organic matter and are typified by dark colour due to the admixture of organic matter rhe saiis are ma-Tily clay and organic mailer With almost no OMTSd grains  Ihtf  they  can  be  considered  imperious  and  expansive  soils  Because  &1  tee  high plasticity.. Swelling and shrinkage propemas of these serfs with changes in moisture GOntefll cracks were observed IP the soils dunng tee dry season visit to the reservoir site. According |g the dnllrng results lhe Lhickness of |hu sod unit ai the saddle dam site rs about 4 nt al ADS-' and 2 m gt aDS-2.
3.6.3 Aiks I in e/Tra chy-Basalt
The rock is covered by COHwmum at the right abutmanl by flood plain deposit in the flatter and depressed areas <jf lhe saddles al ADS-1 a 2 and exposed on th# surface at 1he elevated area at  tee  boundary  between  lhe  Iwq  saddles  The  rock  is  completely  weathered  and  partly decomposed ai rhe borehole ties and relatively ires n ai ihe uplands between the saddles and righL abutrttenl areas As revested from |t*e drtiling at AD6 of the nght abutment of the mam dam  site,  the  Miming  degree  ls   very  high  This  may  be  attributed  io  tee  MW  oriented fracture line observable at [he nghl abutment and lhe predominant regional l.neament/faulting direction at transversal (fraction eg this iradure line. The weathered zone ryf this roc* unit ra
16
Water Work* Da sign & Sap*rFUion Enterprise
tn Msocisdon with IntSrCdaUDEDLui Coosidtinls m: d TechflUCnti PtL LtrLArjoDedwsa Irrigation Project
Geological & Geotechnical Investigations
May 2007
not  peneirated  by  any  of  the  three  boreholes  imptying  chick  wealhered  zone  under  the soil cover The geofog icaJ cross-sedion of the saddle dam site is depccfed m Fig 3.5
3.7    Geology of the Spillway
The spillway line is located wrth in the saddle dam site and will be under saddle 1 As The geology the spillway site is as described under the saddle The information of A0S1 shows lhal flood plain deposits above !he strongly cover the site weathered alkaline rock The geotogical cross-section of the spillway is deputed m Figure 3 6
19
Water Works Design & Supervision Enterprise
to Association with IntereoDtlnontal Consultants and Tadnmrati Ptl Ltd.Fig. 3-1 GEOLOGICAL MAP OF DAM AND RESERVOIR AREA OF DEDESSA tRRIG. PROJECT
4<4>i7nj
3 46000
3 » SASS'
1SO-0-D5
3^00
//     CONTOUR
A/
•
♦-
Retervoir level Hot Springs
Boreholes
A/
Lineaments
/y
Faults
A/
Dam axis
/\/
Fractures
A/ River st str earns
□    Alluvium
i --1 Residual soils
O   Colluvium
□    Flood plain deposit a    AIL aline Basalt
o    Apphanarfc basalt
Sjjfrpq 
3**000
^46UMJ
l*epQ0
250GDD
3
0
21i j Qgg
6 KJ lometer 8i o r,FOl OGICAL MAP OF DAM AND SADDLE SITES OF aRJO-DEDESSA IRRIG PROJECT 
MU
________________________ ______________________________________________ ,44500
t
KiS,....................... .............
~~----------------------------- A-:
*
V
V
i I I I
I
I
I
I
I I I
SPILLWAY ADLE-1
—IM
SADDLE-2
242000
244CZ-3
242500
244500
245000
ilWOC
246000
243000
'5 A
I
0-4 Kilometers
/\Z
A/
Lineaments
Contour
Fractures
Faults
Boreholes
Residual   soils
Alluvium
EB Floodplain deposits _ Alkaline basalt
_ Apphanatic basalt
Rivers/st^ams ColluviumRBNA*amtroNE> ju- mgm
SA TV CLAY (ALLUVIAL) CLAYEY SANOY GRAVEL(REGOLlTM)
highly WEATHERED to DECOMPOSED TRACHYTE
MODERATELY AEATHEREDRNYOllTE
MOOERAf Ely weathered fractureo STRONG BASALTIC TRACHYTE
FRESH  MOOERATELY  STRONG  TO STRONG TRACHYTE
FAULT L'NEAMENT UNFERED) iNFERRCO BOUNDARY
2   THE GEOLOGICAL SECTION DEVELOPED BY THE ENGINEERING GEOLOGIST HAS FORMED THE SAS>S FOR SCHEME OF STRIPPING OF DAM FOUNDATION ANO FOUNDATION GROUTING
3   BOREHOLE LOCATIONS ARE APPROXIMATE
•r»&
o«*»
E
GROUND ElEvA^ON ij
I
partial distance f 3
?   s   1   •*8    f  S
as
RR
■
a
totai distance
• 
R
?!
R4
of
R
R®«o
8
J
963
**»
oR
*
R3 R® 21 ?
LJ*
. II iRijht AiKi'merX NFi
LE worn 512.0m
NATURAL GROUND lEVE L
SX* city {Am^j
,p **’w.e«r g ? t
*       3♦
fi J----- —
IS
------- _.
5
ft
s
§
fir
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ntwr
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f n«i M
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"•wiirtd
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Pl
o                _F                 3
0H 5
is
GS
!!
-•
-E
S
5
z
fe
>-i
J
*
5
H
ooo
ODD
I.JW
83 04
BJM           13Mi
2»»        126 344         1390
1400?
100 6©          1350
396 6B
BBGS
1355
, 4S3 *7
43&0
E       1I
5/4 rfl
MOS
13XJ
623 91
4966
1360
tiin n 7091 1360
749 63 54 90 1365
BIO 62 60 M*
0M93          44 31
IJ6O
1359
899 21         44 23            13»
939 42           4022 | uoffi-U*
39 oa
1359
1»U I
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h
I1
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J 33H19NV                      10 deCOTpOMd
r r>Ch/tC ^yotta
9U« Sc< SMy
Mod«rwt»ty wemnered a»cArrd BASALT
W^e-ocky
MOIL
’ UCVATiQHt DISTANCES ARE PC METERS
2     TMfc GE OLOGCAl SECTOR DEVELOPED BY TX ENGINEERING GEOLOGIST HAS FORMED THE BASS EORE SCHEME of stripping of dam foundation ano fcundatdn grouting
3   BOREHOLE LOCATIONS ARE APPROXIMATE
r «w« Cw*«e<MC M Et»«w
V*«ry </ 'WMw Amm^m
UUC OtOtMA OAM AMO I MAX* AT ION RMJKT
w                         ___ __ ___
•OOLOOICAL MCT1OM
ALON 3 oml
LWAV
q*h
pci0«ir
KMC
•TW4
oMtccsr
****••I
I
■
■Ar Jo Dedessa Irrigation Project Geological & Geotecimlcal Investigadotts
3-8 Reservoir Area
JtaySOO?
The landform of She middle part of the reservoir can be described as flat to gently slopir*g Hood plain The wide area of lhe ro&ervoir is  mapped as  flood plain deposit as  shown on She geological map in Fig 3 i The deposit rs  expected to have a thickness  of about 5 m The thickness of this flood plain deposit was ascertained from the water well drilling conducted at downstream site of Ate village. This well was under drilling by Hard R-ocfc drilling company for the water supply of the village during the field investigation period.
Some remnant hirig. composed of aikahne basalt typify the reservoir area on both side* ol lhe
River An example of such hill is the one at UTM 244d47rn&939160mN and elevation 1375 m as shown in the geological map (Fig.3. l) This remnant hill is made up of fractured alkaline
basalts
Most of the flood plain deposd in the flat lying reservo r area is underlain by aphanitic basafl as observed in lhe rive/ course Some residual soils  were also noted to lie within the reservoir area as shown in the geological map These residual soils are reddish in colour, stiff day. The genesis  of these residual soils  is  associated mainly  with the decomposition of the aphanitic basalt.
The generalized stratigraphy of (he reservoir area is
•    Alluvial deposits
■   Flood prain deposits
•    Residual soils
•    Alkaline basalt
■   Aphanitic basalt
3.8.1    Alluvial Deposits
These are deposited mamfy  along the riverbank  of Dedessa The alluvium is  reddish brown composed of fine sand, sill and clay The thickness of these deposits on average is about 5 m as observed along the riverbank and ascertained from (he drillings al the dam site The aHuvial deposits over lie lhe alkaline ba salt-trachyte dose to the dam site and the aphanitic basalt in the upstream areas as observed in the river course mapping
26
Water Works Design & Supervision Enterprise
la ASHCtlttoo with Interroatlnentu Consulting ind Technocrats Pvt Lid.Arjo Dedess* Irrlfation Project
Geological & Geotechnical Inraidgadons 3.0.2 Flood PJain Deposits
Mayzwrz
Flood plain deposits aro common in 1he reservoir area and are typified by dark color due to tte admixture of organic matter The so is are mainly day and organic matter with minor granular material that they can be considered impervious and expansive. Al places they are mixed and these sediments include reddish, brownish and black soils localized both « vertical stratification and fateral expansion.
3.8.3 Residual soils
They are soils developed tns-ilu by me decomposition of rocks on which i| lies The residual soils identified In the fiefd are associated with the decomposition of aphanitic basalt in the reservoir area These soils cover gently sloping areas where recent sertiements/vilfages are established The distribution of me soils reservoir area s deoicted m Fig 3.1
The soils at the site are mixed with some gravely, pebbly residues al lbs contact wilh country rock These soils are red to brownish red in colour and have thickness up to 3 m at the borrow sites.
3.0.4 Alkaline basalt
The alkaline basaH rack rs observable at remnant small hills in lhe reservoir area and in the river course close to the dam site This basalt outcrops m the reservoir area al places like Chewo hill on the left side of the nver and around Martbo area on lhe right side of the river The surface characteristics of lhe alkaline basalt are Similar Io the rock at the dam site. Il tg pinkish to brownish fractured and weathered The fractures are widely spaced and mainly filled with secondary material especialty at 1he river course The fracturing condition of the rock in the river course is as depicted in Plate 2.
27
Water Workf Deslga & Supervision Enterprise
la Aswetadon with tmercooUeental CoosuliMts and Technocrats ht Ltd.ArJoDEdrssa tnl£atrfln Project Geological & Daoteclmlcal Investigations
Mar 2007
FJatt 2: frsciur* e^rtdiir-on of the ilkaknc has alt as obsarvad in the 'Ivar courso
3.8 5 Aphanitic basalts
Tlws rock u*M was observed at lhe upstream area from the dam site in places like upslream of Ate i^age. Wachamo and Manto hills. As observed on me surface m an Artenshre oulcrop al Wachanw hill and upstream of me Ale village area on the way 1o Yanfa. (he 'OCk is yack, line- grained and strongly jomled The joints are mostly open and cfosefy spaced. The surface exposure condition of (he aphanilic basalt on the left SKJe of lhe nver at Ate area is demoted in plate 3. Uus fraclured aphanitic basalt outcrops oul side the reservoir level
On the other hand, (he aphanitic basalt at Manto area -s highly weathered No fractures were measured on lhe right side of lhe nver as the weathering is so high that the rock 15 almost decomposed and partly changed 1o soil
The aphanitic rock is encountered only at AD7 which ,5 on lhe left abutment but slightly off downstream of 1he dam axis. The aphanitic  basaft encountered at AD7 is  fresh, slightly fractured and its probable ongin is as a sill within lhe alkaline basalt. This basaltic unit ts not encountered in the other exploratory boreholes
28
Water Works Design & Supervision Enterprise
In JUJCClidon wlii lnltrcontmeulJLl CanjuJcints and Tecltnocrsts Pn Ltd.Arfn-DeueiM j nigsciwa fTcjm Gflotogfcal & g?atet waJca) teresUgatlens
Msy20O7
Plate 3 Jointed aphjaltJe basalt exposed on the surface on the left side ol the over ouEsrde
the reservoir level
3.9         Main Canals
3.9.1 General
Two Long mam canab ■» proposed Oh both sides of the river course. The canal lines are covered mainly win clay sod At places along the left canal, weather?# ^kaitni basaltic rack outcrops while at places along ths rigM canal weatherea metamorphic and granite rock is outcropping
Pie general stratigraphy i$
*    Alluvial deposits along stream cfdssirgs
*    Flood plarji deposits in Hal areas
t Residual soils m ths gently sloping areas
*    Aftaimc basaH
*    Granitic protrusions and wealhered metamorphic rock at the downstream area
3.9.2   Left Canal
The landform of th? left canal tine is undulating cwpedsNy in the upstream areas and lhe canal route may possess a meandenrWJ Shape otherwise quite large CUI Wduld be required Id reach the required level of the canal m straight line. Geological mapping was conducted using GPS traversing along Lhe probable canal Hre and tee foi owing points were ncled
_____________________________________________________ 2S
Water Warkj DasLjjd & Supervtsioo Enterprise
tn iLSSOCi AtlWi wl th IntfrconUnanLaJ tanjullajitj iad TCCthjOcraU Pvt Lt JArjtb Dedessa FrrigatJtm Project Geological & Geotechnical Investigations
MiyZOCr?
•    Long portion of lhe line is covered wi1h ofay soil ranging in thickness from 0 6 Io 2 m
•    Most of lhe soiF along me ime is clack soil and somalimes-dark brown soils especially at Sfoppmg hilts and black al flatter ano depression areas
•    Remnant ridges of alkaline baulk rhyolite - trachyte and rolling landforms interrupt the
main canal line in lhe upstream area of the command area
•    A number of river crossings of which three deeper valleys (2 - 3 m deep) were observed during traversing along 1ha probable canal line.
3.9.3   Right Canal
The nghl side of the command area and lhe corresponding man canal line is relatively flat Field observation shows thal |he right canal ■> covered wrlh black soils at most places and sandy  soil (weathering product of the metamorphic  rock) ai places  At the lower portion of probfible canal lmer lhe granitic ridge doses almost to the mrer course area Accordingly, the following pomts were noted
i A number of nver crossings were observed during the traversing atpng the probable
canal line.
*    Brockage of the canal line by elevated land (grannie rock mass) at tha downstream of
the command area
*    Sandy soil covers at places where decomposed metamorphic rock is the basemenl
3.1D Geological Structures
3.1D.1 General
the geological structure mapping and study of the project area focused on 1hB  iden1»fica1ion of major   lineaments,   faults.   fractures   and   land   sliding   indications   Air   photd   and   imagery interpretation  at  the  desk  level  shows  that  major  faulting  direction  >s  NE-SW.  which  is  the direction of lhe dam axis Th*s ma|or faulting direction u m concordance with Lhe Adosa Hot springs of artesian well field in lhe reservoir area at about 4 km upstream of the dam axis along lhe main Dedessa River. The keteketo Hot spring at Wama valley and the associated alkaline dikes at the spring site and at the abutment of lhe saddle dam site are also m NE-SW direction In addition io NE-SW regional direction of faulting, there are also young faults in the NW-SE.
30
Water Works Design & Supervision Enterprise
In AssocUdoo with InlrrconUneotil Consultants and Technocrats Pvc Lid.-
Moreover fieid measuremeni was  made an fractures  on rock  outcrops  al ihe dam site area (right abutment, leh abutment and saddfe dam site}, Cdnsequenlly, two joint set directions (HE* SW major and E-W minor fracture directions) were recorded at the dam site and river course rock outcrops during the field mapping at the site.
3.10.2    Faults
According to the air pholo and satellite imagery mferpreiation rhe major Jineamerrt direction is WE“SW at the dam axis Field observation showed also the game alignment of dikes at the abutments the saddle dam area and at the Keteketo hot spring near Wama River
The recognized fault plane on the massive alkaline basalt at the fight abutment and complete Shattering of the same rock al the left abutment are indicators of faulting and displacement al. the dam site The recognised fault plane at the right abutment strikes at N140^ and dips al 47,_ from horizontal
Moreover, the core sample study d the exploratory boreholes ctose to the fault lunes on both sides (AD3 and AIM) revealed that there exists fauHing along the fool of bolh abutments Two indimed boreholes  towards  the abutments  are recommended to be drilled at detailed study phase m order to verify the fault direction and exaci line on the ground. The trend of these faults on both abutments Is determined 10 be NW-SE These fault fines are also shown on the geological map at Fig 3 I and 3,2
The field observation showed that (he right abutment is  relatively  massive white the left abvlmert *s completely shattered Most of me E-W trending fradunes on lhe atjulmants made ol alkaline basalt are probably  associated with this  NW-SE trending fault The parallel and transversal fracturing are predominantly vertical io sub-vertical in dip
ArJilDflilHsji IrrlfKtlflB Project
Gcologtea I & Geotechnical I nvestlgatln as
MjlfW
31
Waler Works Design & Supervision Enterprise
Io Association wltli hitereontlnen.ta.1 CarxsutlanLs i_nd TechnncriLs PtL Ltd.AjjeDEdessi Intention PrDjtrt
Geologies! & Qeotec httical Investigations
3.10.3 Jofnta 3.10.3.1 General
Nay 2007
Dp dirfitliarr and amount of dip ware mmwed on me outcropping rock jointed 9 C fore with lhe heip of geological compass These Jrtrit/fractiX* meWHVfnentS were Dqn ducted on I hs rocks fit both the abutments saddle dam Site, fWWVDfr area and shell material sde The joints are plotted wtfh the help of windows compatible SSWIN MfthVt separately for «ach specific ?de to anatyze lhe joint onenlaiion al Mtn Site To have lhe overall structural impression all the jfiirtls recorded In lhe Md were plotted together
□etailed analysis of the joint seis is presented *s FoffowS.
Hfl.ia ft'gtM Abutment
Analysis of the joinls measured on alkaline PasaH aulcrops in lh-s abutroerl ■r.'dicale s trial there are three directions PT Jointing These Mt N25fin N2ao  and N 0  with an average dip amount
of al lhe tftreclrpnj reaching 7f/ from honzontal According fo rhe analysis th* predominant fracture direction Is Nfc56g (towards west) as decided io F gyre 3 7 These E vV point sets are believed fo be relate J to the NW trending fault shown an rhe map al Fig 3,7
cD
?
figura IT: m -w plM of <1 + plot UlrecUori hi th* |imdln« bai*H at r lyhr *tmUn*nt [n-JSJ
3?
Water Works Efostgn i Supervision Ebtirprlsn
In UrodsLlcn wtLt: CntenrarrtlnaptU Cenaultents and TecKrUmU PTl ltd,Arj-olcdtssit IitIiJ jUjji Project
G^dIdkIciI & GecEflchdlcal Jnyostlgidons
3.10.3.3   Left Abutment
Nay 2007
The left abutment is simngty fractured The fracture tfreCSons and their dips measured m the field is plotted and analyzed Three directions wWS noticed from I he anatyStS. njtmery N1C3fl N9(]F and N29O* with average dip amount of 71’ from horizontal According to lhe analysis the predominant fracture direcfon is NlOS" ftowardi as deoictEcfin Figure 3$
These E-W joihl sets tn believed to he related to the NW trending fauU Shown Of the map at Fig. 37.
FIgurn IS: ittiro plql of th* K*ntdip direction |r> Uh ■ Ihilint built of lafl Htatmeht (n^40|
3.10.3.4           Saddle dam site
The saddle dam site >oci +6 also fraclured and- measurements we^e made on dip amount and dvftflion The Stone Plots oT these points are as shown in Figure 3 9 The analysis Shows lhaL there are two dip directions, naft>ely N32011 and NI4S5 The joints dip partly !o the NW and P&riry to the SE. The predominant d-P direction is however N32O11 with an average dip angle of
33
Water Works Ossip] & Suparriston Enterprise
In IsidcUlUdd w&Lh kiterwGlliitntAl CatmjSuuitt nn d TwimeenU Pvt LEUArje De Jess* Irrifidoo Project Geological & Geotechnical Jnvestlgatlom
May 2007
Figu?« 3.0 stereo plot erf lhe point direction in the alkaline basalt of saddle dam site | n*3O>
3.103-5 Reservoir area
Flood plain and alluvial deposits  cover most of the reservoir area Rock  outcrops  in the reservoir area are in the n«er course area arid reservoir rimes Dip direction and amount joints were measured m 1he reservoir area bo m on the alkaline Oasall and aiphambc basalt The iomt analysis  is  made independently  for each rock  type The fracture measurement data of both alkaline basalt and maffic rock are plotted and depicted in Figure 3.10 a, b & c
The jointing of lhe alkaline rock at lhe over course has three directions, namely HI SO . N70s and N3305 According io the fracture data analysts lhe predominant direction of dipping iomt on lhe alkaline basalt al lhe river course is N90n (Fig 3 fOa) vrith average drp amount of 76* from horizontal
0
34
Water Works Design & Supervision Enterprise
In Allocation with InterwBtlJisiiLilUoJUttanls indTethDocriti Pvt Lid.Afjo-Dedessa Irrigation ProJ eer
Seologl-e al & Geolectmlcal Inwsilgatloiis
MayZW
Figure 3 10a Joint*™; <jir«|iort Of lAe alkaline beeaK at the r*ver course m iha reserv&r area |n=3O)
I he stereOgraphiC plot o( the points. Iran the aphandit rock n the reservoir area shows throe dip dipectoris  of  joining,  namely  N19Qf,  N253?   and  M2&S0   with  pretfarnmanl  direction  of  M253* (Fit? 3 1flb| and average dip amount a1 75s from hocizonlal
FiBur+ 3.10b: Jointly d>MC04n or OH * phi nidi biaalt Heft ra»»rvoir]. Th» major dip <Jlr*tt>Dn it
»n a«rafl» dip anaH ol t5* (h^Uk
W*(er Works Basics ^Supervision Enterprise
In AisdcIsUdzi wllh [nLtrwnCiJitrtL*l Co rtju-lixnti and Twhosmia Pvi ltd
35AcJd Bedesa* JjTig*Uua Pro]?ct
EteofogJcal & GeatedmlcaJ InvcstlgaUoiu
ITijr MOT
Plate 4; alkaline basalt dike at Ketekelo jprlng clem? to Ihe confluence ot Wama with
Dwtessa River
3,11 Ground Water Condition
The rock of the area is sfrongty traciuibd and is of high potential zone for grourdwaler storage and movement in the subsurface Volcanic rock with such fracturing -a normally a good aquifer The hghly weathered and decomposed Ihm layers observed from the dnil cores can serve as confining layers Study of the fractures from the drill cores showed that mme.’als are precipitaled on  the  fracture  surfaces  indicating  Ihe  percolation  of  groundwater  in  rhe  subsurface  fo understand  the  groundwater  depth  at  and  around  the  dam  and  reservoir  area  preliminary groundwaler dala inventory was conducted on site Accordingly, ground water point inventory of the project area is tabuFated in Table 3.1.
Hot springs wem observed in the reservoir area and within Wama valley They were identified to be fraclure springs. These springs are mamly artesian and have high yeld All the springs are refaled to regional tectonic structure and are aligned along the faulting direction of the area The hot spnngs may be also indicative of rhe presence of magmalic anomaly in the area The ho<  springs  are  observed  to  flow  towards  ihe  Odessa  river  area  These  springs  may  be potentials for seepage under reversed head of water table as a result of high water column m the reservoir area after impoundment However the springs art far away from the dam axis that the effect on the impoundment may be minimal
37
Water Warks Design & Supervision Enterprise
la ASSOtHUtHl With InteramllnentiJ ConsuhtUlti ud Technocrat! Pvt Ltd,Arjo-Itedess* IrdfBUoD Project
Geological & Geotechnical Investigations
Maf 2007
Groundwalcr level was  frequently* measured n the boreholes  during the mvos  bgalion Accordingly Che waler table of the grounrtwater at the valley bottom at borehole AD3 and AO* was at 5.6 m and 2_3 m depth, respectively The water table is at about 20 m below ground level at borehole AD7 which rs located on the left abutment. The water table al AO4 H within 1he alluvial deposit indicating an artesian effect. For further monitoring of 1he groundwater table< two piezometer were installed al borehole AD* and AD7.
Tibia 3.1: Graundwaler paint data □! the propel area
I
No
SO
5putc«
1
Rornarks
X
¥
Z
1
AjftM        <**♦*.        tfota        iu DtftUI ftVW
Hoi|
245711
raws
1*14
* krr- upslrevn
jnrt'jn
1
2SS mS£ at Ad os a ipr.ng
24*42-3
935236
1325
W4«                               fbo^i 4 5         u^tifWri
J
KQljtktlti fixing-
hal     artesian spring
245067
I3&7
along il~-a           ih^nmn-nl WWM MHWy
4
Aqc Deden a rqad
wlffn spmg
21O77S
rasooi
1420
AD$QCET«Df»j
5
AW ViIKje
w«wr wflff
244428
937949
1337
under      d'rir-j      bn*-     tod cover
A
Cofr/nard are-f
Aia-Wr -*«l
2*5207
94*342
1365
tiffed iwlh r.aftd pum
depLn 28 m and r
pir
PvittJiii 1 1 m
VUfffii-WUii&o area
wMer^eii
7
246157
flbtWM
1*47
uTidw drriirjj.                  5 m 5-diI cover
Water Works Design & Supervision Enterprise
In AssodaUon wilt lolfnsntineotiJ CctMulluits irnj Tectmoerau Pvt LW.Arjc-Dcrfrssa tnigaUOn FT Cd Mt
Geological & Geotechnical InuestlgallonJ
3.J2 Se ijmie Hazard Assessment
311.1           Region ai SafaIBoFectonics
May 2007
The she fa loraled on tOUlh west-Highlands and iscuts-de from Ihemain ftTiiqpon Rdt, which MfliMutes me northern part of Ihd African Rrfl Valley The Airman Rift Valley, including its northern Ethiopian branch, is a consequence cf global plate tectonics. Tha Western PEsteau of Eihnjpa is moving north-northwest, the South-eastern Plateau is nwtfng southeast and tho northern parts [Arabian Plait} are moving north-ncxlhcast The 8HB delineated hy thHdhWtefon ofmese 3 prates has a triangular shape (Bw Afar Triangle) a nd fa an area ot extension
Crustal deformations are consequences of loading-unloading cycles of leciontc stresses When siresses  ere released, due to r«mation of rfraotogical and frictional forces  of me Eirths materials, dislocation (earthquakes) taka place These an processes  over geological lime periods to come whereby crustal deform alians can be well predicted and extrapolated irtLu forthcoming UlMperiods, far irislance rhe expected Ete time of j civil construction
Tectonic stress accumurairon and release occur rather pwDdfcaNy and stresses arc therefore perrodict4y released by earthquakes Areas prone to seismic activity have ip consider the sesmiC hazard Of 1he area, i e oonsideralions with regard to conslructipn and safety 01 Chill
■works
3.12.2          Seismicity of the Region
The Arjo Dedessa site is  located *5 tho Mulh-western highland Ol 1ha country  The Arp Dedessa dam site is about 340 km away (fam lhe 5.-S magnitude earthquake of the I9&? m south-western Ethiopia Thfa WthqLMiH location is lhe closesi h*gb seismic potential area Idr the dam site
38
Witter Works Itesign & SuperrfsIOQ Enteriirlss
in AJi*C±aHcm with fiileffin nUrtcnlkl ConautLan ts *flif Tcchnurrsfa Ftl Lt±ArjoDerfessa IrflfflUon Project
Geological t GeotecbnJcal Investigations
lIajW7
3.12.3Selsmlc Hazard
3.12.4
Gr
ound
Movements/Dis
placements
There
is 
today
no  systemalto
monitoring
of  ground  mot
ran  or
crystal
def
ormations 
in
Ethiopia
and
Che
site
TO   estimate
ground   d
isplacements 
™   ere
toere
fore
referred
fb
global
observations of satellite geodesy, which suggests plate movements in the order of 3 5 cm per year Thus, averaging and emptying toese observations  we may  derive to lateral movements  (diversion of plates), vertical movements  (faulting) or oblique movements  In toe order of up to 1m per 20 years
3.12.5    Ground Acceleration
Assessment of lhe seismicity  around toe srte was  made based on seismic  hazard map of Ethiopia produced by Geophysical Observatory of the Addis Ababa University According to the map the Arjo Dedessa site lie in too zones with horizontal acceleration contours or less than M onto*
|n general it may be concluded Inal the site is situated m seitmically less active locations of the country  and toe expected values  of ground accelerations  from earthquakes  m the site or any macro-seismic phenomena wiki not exceed accelerations of lOQ-cmr sJ (- 0 1 of g) in any part of lhe site
3.13 VES Survey Results
Conducting a geophysical survey  was  found to be necessary  not only  to determine the overburden and fractured/weathered zone beneato but also to fill the data gaps  in between boreholes along lhe dam and saddle dam axis. For the intended study VES‘s were conducted at the dam axis to complement toe drilling Four VES's were used along the saddle dam axis and another 2 VES's along the spillway hne
The absolute tocaton ol the VES survey points » summarized m TuUc 3 2 and the location map «s 
P'C[ta td by the contractor and attached
r
in tne Appendix F .Geophysicar survey results" under a
separata report
______________________________________ 4-0
Water Worsts Design & Supervision Enterprise
la Asseciaitatl with InCercontlntntal Cunjultaats and Tecbnoerau Pvt Ltd.A-TjO-Detfc ill IrrijiltaD Project
GcDtagtcA) k 0#oi«eLtdcai l nves tirade tu
Tibi, j a ves pjinis iii Arj^Dedesjijiie
May 2007
VES No
Easting [mJ
Northing [mJ
Elevation (m)
’1
" 242-137
WlOST
13669
2
242560
wirsfl
1377 6
3
743CS4
942307
1342 4
4
243129
942340
1329
5
244850
■942445
1357.2
i
244620
942505
1359 2
7
244352
942730
1352 2
«
244079
942962
13SS 5
9
243287
BC013
1335 7
1325 1
______________1
The summary of (he resistivity survey results til the dim and saddle sites .s are Wimnuriud ih Tawe 3 3
According la the fMrttfvty values obtained, nfl Significant sal «W II detected in the valley
vi or ihe cfsm axis survey a™ The resistivity $wve? result of lire saddle dam srte srtgvvs 
□tf.X/viums cow above weal tiered and ftactvred rack (Tafcle 3 3)
10
243254
$42549
JI'
Water ffnrfc Design t Supsrvfclon Edtorpriis
Ert UHtfllfoii vilfa Intfreoatkii e LaJ CanjuHanta and Tedhnactlta Pvt LdArja DeJems Irnmioq frajecl
Geo]a rlca [ & Geo [4 etmicM InvtsLl^ailLias Table 3.3: Summary of th e VES td rvey
May 2007
VES
Na
Layer
Depth
(mJ
Resist
(Ohm-m|
Formation
Location
I
1
a-7.5
3923
fresh rccK^uldef
Dam ■ate, tell
2
7.5 ■ 48
774
lighUy fractured zone
3
bel™ 48
2354
fre±h roek
4
PT”
0-2
T?
lop soi
3
2-17
770
sTighllyfraclured batsH
6
1
0-25
630
bouldcreous material
Satfd e dam ;i- &
2
2 3 - 35
16
tfccoiVMd bataU
3
Stiff# Ji
75
weathered basalt
7
1
0-24
520
bouidereo^s zone
2
2 4 - 73
44
tfecompcsed baseH
3
below 70
137
n>ode<ately weathered bai»n
3
1
0-2 7
103
weaihe.'ed basail
2
2 7-33
36
decwnptised basall
3
below 83
si
weathered b.isali
a
1
0- 3
8699
fresh pawn
2
3-24
1462
si^hdy fractured
Dam #kis, right b*nh
3
OtUjw 24 1
8314
Trelh bfiialE
10
1
0-14
155
Icfl SC4
2
14-10
653
tr«» Pauli
3
W-54
IftS
taealhfried baaaiE
_________________ .
42
Water Works Design & Supervision Enterprise
m AisortiBofl with krtmwOMfiUl Conan ItMts ind Technoerata Ptl LtdVjuDEdessi lrrt£iCloc Project
Geological & GeotBchnlctJ lowstlgatiDns
Msr ZM7
4.
Const
ruct
ion materials
4.1 In
troductio
n
Asse
ssment
ol
avaifabiMy  nt
various  construction  materials  Suitable
for
the
purpose
of
constructing a dam at close proximity tp the proposed 5>te was initially conducted visually A closer investigation was made to determine suitability and determine available quantify Based on the initial assessment, the construcliOh materials further studied ncludcd the following
*   Clay material
*    Sand
*    Rocks for concrete aggregate
*    Rocks for shell maleriat
*    Rocks for nprap etc
Considering the foundation condition and available construction materials  in the area of Ck'dessa dam sue. the most suitable type of dam for rhe area t considered to he rockfi'l dam with central earth core with Iransmon filler on each side of the core and adjacent to the uts nprap Clayey material is m general rare Highly fractured and weak rock is available m large quality <n the project area
Consrfenng  the  above,  the  bulk  of  IPS  dam  malenal  shall  be  rockfill  material  winch  is abundantly available m the project area dose io me dam site and spilhvay area.
The findings of ihe construction material investigation are summarized here under
4,2       Clay Materials
Fine day  material suitable for use in dam sections  haq seen identified at several scattered locations  with in the project area. The reservoir area is  mainly  covered wnh dark  expansive days. Source of red day  had been identified at locations  outside the reservoir areas  The potential borrow areas are located on high grounds and all are currentEy being used as fa^m areas  The five borrow areas  identified are named after the villages  they  are located in as Chtwo (CUB). Obse (O6B), Dhendessa. Maribo and Ate Obse rs  located downslream ol the dam axis While ir>e real are located upstream
43
Water Works Design & Supervision Enterprise
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Geologies] & Grotectwjcsl Invesflgittons
Maj 2007
A total of 53 test prts were excavaled manually within the identified clay bonow sources The depths  of lhe tests  puts  excavaied varied between 0.75m 1o 5 m. Based on the test pin excavated, me total estimated volume of matenal available from the five borrows >s m excess of 2 miftion cubic metres
4.3     Shelf Material
Highly fractured volcanic rock was identified close to lhe dam site This material is available m ebundant quaniriy  although it may  lack  good strength The identified Quarry  is  totaled 1km downstream of 1he dam axis
In order to learn about the depth and quality of available material, borehole ADQ-1 has been drilled to 15m. The borehole rqgs are provided m a separate report Similar material has also been denlified in another site known as Guche area located at 12km downstream of 1he dam axis at GPS coordinates of 234469E and fr434flON to serve as a reserve site A large quantity of usable material is eslimaled 10 be available between the two quarry sites for use as a shell material
4.4 Riprap material
Two quairy areas have been identified for use a source for a riprap maierral Trie two sites are localed at places known as Buketa and Colism Bukela <s located about 6km upstream of lhe dam ax« cm the right side, where as Colisirt is localed 26km down slream from lhe dam axis on lhe left side
4.6 Concrete aggregates
Coarse aggregate quarries for concrete work have oeen identified at two locations designated as ADQ2 and Mariko Representative samples have been collected from bolh quarry sites and laboratory tests conducted on them
4.6 Sand sources
Borche, Loko Sefera Loko Bridge and Tullu senbett sites have been identrfred as sources for sand The sand is  to be used for concrete works  and fitter materials  withm the dam Tuflu Senbete source is located in the bed of the river Oedessa, white the other two are located in the bed of tributaries: Bqrche and Loko. The approximate distance of al! the four sites from the dam ____________________________________________________ 4$
Water Works D e sEgn & Supervision E atarprise
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Geotoglcal & G<otectmltril invwUgidoDs
May 2007
axis  IS about 60 km. Representative sand samples  have beta coveted from the thw sites Gombe. L.c-kD Sefera and Loko Bridge few laboratory tesliflg The fourth site «H rU3t accessible due Cd rain and therefore no sample had bean coltected Summary  of the (abOWlny  tests conducted and inter.pre1at.ve charts a re provided m Appendix 
45
Witer Works Dejipi & Supenislon EotsrpriM
to AliodadijQ wim la reran du mUJ CortraltulJ *MTeeKMcn.[j Prt l«lArJoDedessa Irrigation Project
Geological & Geotechnical Inrestlgatlons
May 2M7
— -------- --
5.      Geotechnical Design Considerations
5.1      Construction materials and Design Parameters
Ddarls  of  laboratory  tests  conducted  can  be  seen  in
the
tab
test  result  data  compiled  by 
CDSCo  A  brief  discussion  of  the  laboratory  test  result
s  rt
give
n  here  under  based  on  data
analysis and the summary provided in Appendix 0
5.1.1 Clay materials
The  Clay  borrows  identified  in  the  project  area  are  si
milar
m
origin  (mainly  residual?),  are
brownish to reddish In colour and also exhibit in general similar properties regarding plasticity Nearly all of them plot below lhe A fine signifying property of high plasticity sm
The results of the Atterberg limit tests showed that the PI varied between 4 and 68% with the average in the order of 24% The average LL was in general greater than 50% signifying high plast>a1y properties The average swell value is just below 50% for the whole borrow sites 
tested underlying potenliaJ swelling property The PI value for Chewo is lower than the other
clay sources
Test  results  for  dispersion  progeny  using  pinhole  testing  apparatus  indicated  that  the  clay maienal Is not dispersive
The coefficient of permeability is quite low (an average of 10*cm/s) making it quite usable as core matenal to minimize seepage
The  average  natural  moisture  content  of  the  clay  sources  varied  between  8  and  16%.  with Chewo bemg the driest and Dhendessa being the wettest Moisture application wnl n general be required to get it close to the Optimum moisture conlent to attain maximum sirengfh The variations m the optimum moisture content between the varrous borrow material is insignificant with the average for  all the clay borrows bemg around 37% Due to the property of the clay matenal,  workability  problem,  in  general,  could  be  expected  The  way  to  get  over  with  this problem is by undergoing a test embankment prior to construction and assessing the best way to  conduct  the  compaction  works  Another  way  to  deal  with  the  problem  of  workability  is  to leave  with  relatively  tower  slrength  by  compacting  the  so«l  few  percentages  tower  than  lhe optimum The lowering of the day slrength is expected not Io have a major effect on the dam
4G Water Works Design & Supervision Enterprise
In Association with IntercomincnUl Consultants and Technocrats Pvi Ltd.Arju Dedess* Irrlifitloo Project
Geological & Geotechnical Investigations
Miy 2D07
in terms of stability since lhe proportion of the cart in- the dam is not signrficanl compared Io the shell matenai
The triaxial shear strength tMls conduced gave the values reported m Appendix  Tht
etfeclive cohesion value reported is well higher Chao could be expeded *or such material This could be related to non saturation of rhe soil or, strain application, sample preparation elc Subject SO further study of 1he Irraxial fests, a C of 0 value shall be used for lhe analysis.
The various properties of the day are summarized in TaWe 5 1
Tabl* $.1 - Summary of clay d*vJgn parameter!
Property
Unit
Value
Mqisl unrt weight
Knfrnn
IS 4
Saturated unit might
KnJm1
18 5
Submerged unit -weight
Krum1
8S
Effective    angle    of    internal friCNGn 0
degrees
30
Effective Cohesion C’
Kn/mT
0
Total angle Of internal friction G
Degrees
28
Effective Cohesion C
_ ■- -
KrVm1
1--------------
38
Based qn USSR's average soil properties, the average values for the soil is given below
•    MDD* 1310KMm3
•    OMC = 36.3
•    Void ratio *1.15
- K ■ 0.16X1O-Gcrrdsec
•    Csat = 2tHtnJm2
•    Phi ’ 25 degrees
Most of lhe values reported agree well wrth the average values F urther revisron of the vanous values may still be required as further data becomes availaUe during the detailed desert stage
47
Water Works Design & Supervtslon Enterprise
tn Assorts ton with tnlereoncinsatal Conan Jc*nts and Technocrats Pvt LW.Afja Dtdfma IrrtfAtlon PlroJ eel Geological & Geotechnical [nmtlgaticos
5.1,2Shell Material
NeyZOTT
The shell material source is ad)*c#fil to the dam site Comparing the dam site geological condition and the atft¢ shell material quarry area it was considered Ihat whatever rs encountered at the dam srie is OKpe-cted to be available at the shell material quarry
Looking st the ttrsl results oi me shew materials d was observed that they are generally weak in Slrengih. Comparing the point road Cesls conducted on irregular samples during dry and wet condilion. it was observed that lhe material is weak Considering that the point toad tests were corrected for shape 1he average values obtained for dry and soaked conditions are 83G and 7S0Kpa respectively These values are considered as me*um sbengLh class.
Considenng lhal the core size used for UCS test was the standard N size core (54mm rfca). the average UCS value based on pant toad resuhs is in the order of 19 9 and 10 ? (or dry and soaked condition
The UCS and point iwd test results showed that the shell materral is not la the slandard the! mosi rock M materials are specified to be Aj rhe only economically available rocMill material is the relatively weaker roc* which is m abundant supply, one has 1o make use of n in the dam by accepting ihe lower strenglh and designing -1 accordingly At laige scale rackfill Inaxials arc not common, shear strength values are normally taken from data base compiled by others
Considering urnl weight of the rockfill to te in the order of 21KN/m3 and corisidoring dam heigJd of 50m, the friction angle of (he tow strength rockfill is estimated to be 3&13 (Indraratna et al
1993). The problem with usrng such matenal is expected to be crushing ol the rock fill and lhe material ending up with large properfron of sand and silt size making ine rock (ill non free draining. If this happens, 1he matenal tan sail be used but must be zoned and drainage provided High modulus ol compressibMy can be attained for such material. In order Io have a good contact and Intartoc* between the larger sized rocks and minimize compressibility, water applcalion during placement and compaction may be necessary
During construction, the fines passing 2 5cm sieves shall be limited to a maximum of 40% by weigM m order to achieve 1h»s conirador needs to carry out a trial of blasting operation Effort shall be made to ensure that excessive percentage Q( fme is not incorporated m the incoming quarry run matenal by provision ol Screening facility or otherwise
____________________________________________
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Water Works Design & Supervision Enterprise
la AjMcUdon will] InEercaetlMlij Coosultutl >ed Ttttmticrtu ptL Ltd.ArJoDedtsaa  liriEttioU  P™1  «*t
^logical &fl&^chnk il laveatlgaiioiis
May 2007
A lrtal ^kmen,
m
„.™, A »a kn^
g
«,«d prior .' pronto. »- *■*>- ■>*"••* '“'“V >’ rocfcfiti shell
xz xx
XXX »< .he
d 'a 'n"'9
Tabi* 3.2: Sumnupv tri n^f dt*kg» p*ra™tere
Property
Value
1. SHELL MATERIAL
1 Unit wefghi |KN/m3)
21
u Angle cH Internal Friction I degrees i
38
j
5,1,3 Sandy materiel
Tho Ml resUtls  Conducted flfl sand includes  grain Si« distnoutian permeability  and organic content The grain A&u distributer! showed that the sand is  wdt graded The effect of a fine percentage has  teen nolcd flrt ffle some of the tests  conducted One of the erttefta for sand inter being NO unco nF fled cdfnprwwd strength, presence of fine percentage and its  effect shall be yarifted ty &ddn>oflal bucket testa dunng the ce-ailed design si age Id determine if lhe sand cflllapses dunng movement in the dam
The organic con lent observed in lhe sand qbarnes also >i mtnu-nal especially considering that Lhe sampling had bcm done prior to the ms|or rainy season The fricbon angle found from 1he test itEuHS is quite high That is nol however expected to he a major influence in the design of the dam.
5.2 Filter Material
5.2,1 General
Tha autsectiwi discusses 1he materials ava-.iaOle for filter and drainage Sng design of filter ior Dedessa dam Filler sources already identified and their properties are alW discussed
Additional investigations and test, ng th&i need to be conducted during the delated design 5tanc
art »|$0 highlighted
4A
Water Warks Design &Super^|Oh Euterpri^ ~---------------------
In As^daunn wim ln«rtflnuaBQtaJ Consume-, 4Bj Tflchnoemts m Lte.Arjo-Dadesss Irrigation. Project
Geological & Geotechnical InvastlgatlotLs
5.2.2  Field Investigation
May EM?
Prospecting for suitable sand sources has been conducted during the geotechnical held ’-vork around the project area The prospecting has  concentrated on locations  downstream of the proposed dam on Warns  and Oedessa river All of the sources  that were investigated were stream deposited sand The following were the names  of lhe stream and the locally  where sand sources had been investigated
THjle $4                   Loc^tTQn of CFay source am*
No,
Locality Name
1
Borcht
2
Loko Sefera
3
Loko Budge
4
Tulu Senbtto
5.2.3   Laboratory Testing
Laboratory  testing that mainly  consisted of gradation analysis  was  conducted at CDSCO laboratory  in Addbs  The laboratory  testing for sand had been done at Construction Design Share Company  (CDSCo) The full laboratory  testing Jesuits  are provided in the respective laboratories reports
5.2.4    Dam Zoning
The basic dam zoning proposed for Dedessa dam is a rockfilt dam with a central clay core material wth upstream and down stream timers and transitions
Transition material of intermediate gradabon freed to be provided between the sand hirer and the coarse rock fin at both upstream and downstream The transition could be eriher one or two depending on the particle size difference between toe sand filter and the rock  firt shell The sand filler is  also proposed to act as  dram arid sufficient thickness  needs  to be provided considering core cracking. Relatively impervious material needs to be provided dte of the filter in order to keep the seepage water within the filter drain zone
Both  rock  filr  and  transition  materials  are  to  be  attained  by  blasting  of  the  available  vttcanie locks imce there arc no other naturally available suitable materials
50
Water Works Des l<a & Supervision Entc rprise
to Msamdaa with Intercontinental Corwultuou ind Technocnu Pvt Ltd.Arjo -Dedem Mctltan Project
Pipnlnrlr& Rentaf hnlcal Investl^adons
Ma? 2007
Continuous (Blanket) horizontal filters are not required to* the mam dam since the foundation is rock  not affected by  rhe expected hydraulic  gradient. Only  finger drams  are required for the mam dam to take seepage water safety out of the dam The drainage can be in the form of strip drains or perforaled pipes
The thickness of the downstream and upstream filler has been estimated to be in rhe order of 3m and 1.5m respectively  considering ease of construction and dramage capacity  Detailed calculation Co determine sizing and zoning needs to be done al the detailed design stage
The gradation of the transition material required to bridge the gap between rhe sand filter and th* shell material can onty  be determined accurately  once the gradation of the shell is accuratety  known Al this  stage only  a guess  estimate of the gradation of the shell material co-jld be made from consideration of fracture and joint spacing from the geological logs  of boreholes drilled for construction materials
5,2.5   Filter Design
Grain s*ze distribution curve of the clay  core material has  been analysed The Iwo bas*; functions of filters and drams m earth and rock fill dams are retention function and permeability function
The Classic  Terzaghi cnteria D15.i'dS5 < 4 addresses  lhe retention roquirement and the D15Jd15 > 4 addresses  the permeability  requirement The filtering, segregation, permeability, stability requirements have been considered in the design of lhe sand filter band lo retain the fine clay material The fiber design criteria used here is based on an extensive laboratory study earned out by Qunnigan. Talbot and Sherard
As could be seen from the gradation curve the clayey material identified is very fine. For very fine clay base sort, the (oilowing critena were used in designing lhe filter
* For filtering, maximum D1 ST shall be less than or equal Lo 9 XdBSb but no! less than
0.2mm
■ For permeability, the minimum D15. shall be greater than or equal to 4 Xd15b but not
tess thanO 1mm
- The allowable fitter design band must be kepi relatively narrow to prevent use of gap
graded filters
51
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Geological & Geotechnical lovestigaUons
MayW
* The designed filter band must not have an extremely broad range or particle sizes To
prevent use of possibly gep^graded filters
■ Segregation of the filler during construction shaN be minimized
Considering the abWft criteria. Ihe sand filler shown in Figure 5.4 has been recommended Comparison of the available sand malerial and Ihe designed Titter shows that the sand obtained from Dedessa shows lhal i| does not fd within the designed fitter band ma King it not suitable for the purpose. It has a considerable amount of fine to prevent it from being pervious Besides it has  a  cohesion  property  that  would  give  an  unconfined  compressive  strength  that  is  not required Tor filters
Further investigation to locale suitable filter material is therefore recommended to be carried out dunng the detailed design stage If using all natural sources  proves  to be difficult or expensive, crushing of available rocks  shall also be considered The revised selected filter band for the clay material proposed for use as a core is provided under Table 5 4 it is to be noted that the revised fitter band is made wider to accommodate wide range of filter material
Tatis 5.4      SrltCted Design Filter Gand
Sitvfl No.
Sieve Opening |mm|
% Panin
r
25
100
W
95
90-100
No. 4
4 75
8S-1Q0
Mo 10
2
75-100
Nd. 16
1.18
70-100
No. 20
0.84
65-100
No 30
NO. AO
No. 50
No. 60
No 100
No 200
06
042
0.3
025
0.15
0 075
50-100
40-95
30-70
25-60
5-35
0-5
______________________________________________________________ 55 Water Warks Design & Supervision Enterprise
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G*ologjeal & Geote cJinJc*-! lavestJgatloM
May 2007
5-3 Permeability of Main Dam, Saddle Dam Abutment areas
The coeffkient of permeability (K) of 1he varr*ote head tesl conducted in borehates of Dedessa site vanes between B 74E-04crrUsec and 1 50E-O6 cm/sec. These permeability values are
8
generally  below W mfcec.
Therefore  Ihe  soil  cover  of  the  S4e  can  be  considered  as 
impermeable The permeabdity values of ihe msilu railing head test results are tabulated in Table 5.5
According to the tesl result at Oetfessa geotechncal investigation, ihe averages Lugeon values lie below 10 units The Lugeon values al A£J3, AD4 and ADS-1 are very high. The les1 result al upper rones of these boreholes section varies in the different test sections conducted The tests from ihe boreholes on the tap of ooth abutments show mat only the upper sections, i e up to 1he depth 8 to W meters there is considerable amount of wate* irdake and when if goes down the Intake amount decreases and finally it becomes nil This is due to the fact that th#
53
Water Works Design 1 Superman Enterprise
la Asucladon with iDtercontlaeiiliJ CoiuuLt*nU uid Tw.hnocrats hl Ud.Arjd Dedmi [rrifltiM Project
GaolDelcal&GeotMbnieairutestigfttlgM _
_
MayW_
day  materials  from the weathering of upper l«tlon close J  1he fractures  and made it impermeable Mort OMf 1he ft Sts in 1he borehotes Ctase to fault W lineaments (ACM and upper pan of ADS) show that there is no change in the amount of intake Thwa boreholes sre drilled on the fractured zone or the vsfcy  bottom sbutmEnt. The geological mapping has  also jndicated fracturing Of Ibe abutments  at tbfi surface These high Lugeon values  &f me test indicate thal fracture zone with wde openings wot in the TOOK II Mme zones  al Ihfr indicated depth erf th& Dedesaa site
Therefore cement grouting is  recommended io be conducted to ourta I seepage IhrpLbgh foundation Of tne mam and saddle d&ms. The summary of Lugeon test results is tabulated in Table 5 6
Tab* 5 5 Summary erf tailing ht j rt pfrmtablllfy t««1 mult
Trit 5«elJon
BH
Casing
8H No Test
Frgim
To
Cham
Diim.
Pt= RM f ABILITY. K
No
(ml
t™i)
(cm)
(emt
OWWC.
AD1
1
3
55
1100
li.M
1 47E-D4
AD2
1
3
5
IlJW
11.50
4.5JE-C4
AM
1
5
5
-------
il«5
11.60
5 53E-04
2
fl
12
11 B5
11.60
1 5€-04
1
5
a
11 60
11 60
1 SSE-Mi
2
B
ii
11.60
11 60
4 44E-06
AO6
3
ii
15
11 60
11 60
6 5E -04
4
15
IS
11 60
11J»
1 ZED4
5
ia
23
r n 6o
ii 60
SflE-M
6
23
26
11 60
n 6d
1 26E-C*
7
26
26
i----------------
11 60
■—i--------
11 60
■3 74 E 04
AD?
1
5
T4
It 60
nw
5 5E 05
ADS-l
1
5
11 60
11 60
3 6E06
2
B
11
11 60
1160
1 Q7E-O4
54
Witer Works Design 4 Supervision Enterprise
tn AsMciitten wLib kitertontliieanl tenauiunis and Twhnomts PvL LtJ.*rj 0 Dtdt&si Irrtgalk q Prejffl
Geological £ Geotectnikil lnve$t^atlcms
u&r 2M7
Table 5.6. Summary of the Luge-on TOkM1
0H No
Test Nd             Teal Se&Eofl
Average
Luaeon
AtH                            1           ■3 5—11 5             30
2            11 5- 164
3            16 5-21 5               00i
4            21 5 26 5                OS#
' 5              26 5 33 3
04$
ADZ
1 M* 13.4 26 12
2            13.4 17 3               0 73
5            34 40 - 4 0             004
a
17 8 ■ 23 5
0.87
Remark
oermeabla
water t Ahl
wAier tghl
waler 'jhl
water t^ght
permeable
water tight
waler light
*4 '> oerrn*at>*e
waler t-ght
4
1$ 70 - J4 J
5.79
, permeate
ADJ                           1            14- 17
358                          waler t»gM
2            21 45 - 25
4
7&6 a<f*y berrre able
3            25-30                     0 06                        penreaWe
4            30- 35                    5 24
5
IE ■ 4-Z
d
’•a^ty permeable
6
40-45
0 97
waier
------- T"
45 50
8 74
permeable
8
soi-as
1 23
water tight
id
ii
60 65
9
k
waler -gnr
85 ■ 70
0 23
waler t gnt
12
76-31
2 71
water t 3hl
13           8i - M                    0
AD4 1 5 2-3* 0
2 io- 15 33 07
3 15-20 34 71
4              ZO - 2* 65               l 31
5 25 - 30 19 85
6 ■30- 35 21 54
7
B
d
35 - 40
B 49
40-45 17 19
45 50 22 04
ACS
1            5-9
26 87
2             10-15                      16
3
4
15-20 16 53
20-25                      1 59
water t jnt
water t gnt permeable
permeat-ie
water nght
permeable
permeable
fairly permeable
permeable
permeable
permeable
permeable
permeable
waler r j.nt
5
6
7
25 - 29 8
1 17
waier *»ghi
30-35
21 86
35-41 7
^permeable
Il 52
AD7
permeable
1
10- 17
l 52
2
waler tight
19-22.5
2 B5
water lghi
3            22 5 - 2?                 1 25
4            M - 20 1                311
ADS-1 1 13 17 11 67
waler light
2 17-22 7 99
3 21 8-25 3 24
ADS 2
waler tight
permeable
fairly permeable water' ght
1            6 io                       0
water bght
2            10-15                    0
water rjhl
3
13- 22 2
D 14
water ?jy»|
ADSP
1
18 ■ 24
38
wM*f
55
Wttxjr Worts De sign & SuparrUfon Enterprise
tfl Jif»<WKn ■rich Lnt^FcaffttnentU CbrnmlluiU 108 TMhHocnti Ptl Ud.Arjo Dede^ai Irrigation Project
Geo Jo glc al & Geotechnical Inyesagatl&ns
May 2007
Title 5,7;
Summary *f
permeability twl rtri Mtt* for berth |«l ty
pes
Lugeo
n Values
Cceff. of perm
eability IK
Formation
Borehole code
High
Low Average
Test sections
typ*
(Material
Avor
age
Flow type
Rwom
merwIiMl
Turbulent
30
6 1 g-OB
4 5E-CIS 5 IE-06
!
Ad
AO1
AC1
AD1
AD1
ADZ _
AD2
ADZ .
AD2_
AD2
AD2_
A»3—
AD-3
6JO-1U0
1 VSO-I.JGAO_
16 50-21 50
21.50-26 50
2B.50j3iS_
0JM>-'i3-4p.
H.4D-1T B0
I 17-60-23^1—
23.eO-2B.65
29 20-34
_
_
30
1
1
34.40-*0'QjL .                                  36                      10
20
13 .
IS
15 ;
0
9
6“ ^11
13__ if___
13
Laminar Laminar
Dilation
Dilation Turbulent Vod filling Laminar
Lanwn*/ Laminar Turbulent Void tilling
0
0.
1
'fi 2E M QOE + DD 0 BE-Dfl_________ 5 3E-C&      0q'0c£e*0+£oi o ■1i 0S6E-0-0oa
■ ^l-i-a- --E-- jjgTs z*<m I *•□£-«—
l'         1 0E’O7
2S
0
1
6
0
4
B
?5jE-C6
' 9 3E-DB ' l SE-07
' 6 5£-O7 3 FE D9 4 2E-M
3.5E-AM A4E-P*_____ ,
a.iE4M ra.BE-os _
e.zE-aa .' i7. c“
g.JE 06 ll'3EJJ7
5 6E-07     7 SE OY
4 7E-09    5 BE-09
Tse-ar
JJE'-CB
I
_
“
i
2'.ie-w
AD-3
AD-3 _
AD-3
7AD-3
_
xo
AO-3
AP-3
AD-3 __
—.An 
4^’
Y1 50^00 _
25 00-30 00.
^0035 00_____
"35,tX>4p.LpP— ■
40.00-45. DO 4S.OO&OJ?Q_
50. DD-55.09
ssoo^oopL—
50 00-65 9°
6
"12
Turbulent
T urbUlcn!
I jftdlf"! Turbols*?'* _®
6
1
1.46-06   ■ 2.4&«_
z 7 2"tE-o-0- 7 .
1 2
■>        '  iBtion
D----- T~D4afon__
1
1 5-3E'O6
_ '3.6E_-W ,
3 7E-05 3 6E-07
1 5EJW .
B 4E-07 9 7E-D7 | l 6E 07
I.7E4J6 , IZ?SE<*
'"l 9E-0&
' 1.2E-07
' 2.OE-09
iiE-o? . 4 4E.QB
0
1 ___
0
<miBpsS^
’   0 ~~D'E~T‘00''1S 64FE-QUf0l
3 2 £-07
0 OE+00
’ 4 7E-07
6S.DViL^i=i——
7000-B1^
c QE'tOO 7 DE;09^_
6 7E4»_ ,
AD J ' 8l OCh«J»--
| i amiftM ~ — dilation
Wu&h cnJi
"ujcijiwg. _
Laminar
AthL_
□ikitiQn Turouient
-—- ]3.5E^_- ' J3EO6 .
A£>4l^-
>Pt*______
AtX____
fX53_—
"1
3_.
0
■D_ 41
' *1— 
V? _
20 .
’_g_
JJ __
lx_
0^-T ll_ tieSlEU
2  29?___
"“^ldW*!9— 
0
0_
39
35
1
Z iE-0fl„ '3 5E-O0
“TaE^fi
2 6E 06
■<'2E_-06_
2OE-O6
56
Wash o*4 L -^=—
M;
r\ni JArjo-Dedessa lrrt<atlon Project
Geological & Geotechnical Investigations
May 2007
AD-4
30 00-35 00
39
22
30
Turtjuienl
22
A 04
2.7E-06 7
1 4E-06
1.6E-O6
35.004000
7
4
5
Wash duI
7
8 9E-07
5 0E-G7
AD-4
40.00-45.00
6.2E-07
35
17
24
Void filling
17
4 6E-06
A.O4
2 3E-0G
45.00-50 00
41
22
3 2E-06
30
Turbulent
22
5.4E-06 ■
29E-06
AD-5
5 00-9 00
.
3 87E-06
31
6
24
Void filing
6
3 9E-06
6.0E-07
.
3 04E-06
AD-5
10.00-15 00
18
0
11
Wash out
18
2 1E-06
0 0£*00
1 3OE-O6
A 0-5
15.002000
19
3
15
Wash out
19
2 26-06 1
3.5E-07
1 71E-O6
AO-5
20 00-25.00
3
2
2
Olation
2
3.0E-07
2 1E-07
AOS
25.00-29.60
17
1
9
2 29E-07
Voxj filling
1
2 2E-O6
1 5E-07
1 14E-06
AOS
30.00-35.00
25
20
22
Laminai
22
3.3E-06 |
2 6E-DG
2.54E-O6
AD-5
35.66-41.70
22
16
19
Tuftuteni
16
l"2.3E-D6
1 6E-06 i
' AD-7
10.66-17.50
2
2
2
Laminar
2
3 2E-07
2 2E-07
1.96E-06 2.66-07
AO-7
19 10^22.50
6
2
4
Turbulent
2
7 3E-07
2 6E-07
4 46-07
A 0-7
22.50-27.00
3
2
2
Void filling
2
3 2E-07
1 6E-07
2.2E-O7
AD-7
26.50-29.10
17
3
13
Void filling
3
2OE-O6
3.8E-07
1.4E-06
ADs-1
13.00-17.00
19
17
18
1.7E-06
1 3E-06
1.5E-06
ADs-1
17.00-22.00
11
6
9
Citation
6
1 4E-06
6.6E-07
1.2E-06
ADs-l
21.00-25.00
18
4
12
Void Mlmg
4
2 0E-06
4 6E-07
1 30E-06
ADo-2
6.00-10.00
H)
0
0
Laminar
0
ADi-2
10.00-15.00
1
0
1
Dilation
0
ADs-2
16.00-22 20
2
0
11
Dilation
0
A.DSp
18.00-24.70
5
3
4
Turbulent
5
TTTft+.ft-S-i n?A«ikrft Tt.ftftjiVn fl'. P-Hiftift mrtn Emu rm.+.th..; J - iArjc Db itEsia Irrigation Project
Geological & Geotechnical Investigations
5.3.1 Reservoir area
May 2007
A number of test pits  were dug on four borrow sites  in the upstream area from the dam site and along the saddle dam ax*s  Id understand the reserve and quality  of the clay  material and to study  the hydraulic  properties  dF the material as  foundation Study  of the test pits  dug for the investigations  of borrow material for clay  core of the dam shewed that the 1hey  are characterized by  reddrsh brown clay  with minor sand and srlt The pits  at the saddle dam site showed dark brown clay soil
The pitting, drilling sampling, insitu permeability  testing conducted to investigate both saddle dam Site and clay  material in the reservoir area reveal that (here are two prominent soil layers above the fractured and weathered alkaline basalt These are the dark  brown clay  associated with alluvial-lacustrine deposits  especially  at the saddle dam site area and middle of the valley where the major part of the reservoir area lies  and the residual red sod having nodular and uniform clay  layers  at the proposed borrow site far day  core located mosiry  slightly  up from the intended submerging area The thick  lacustnne deposit, which covers  the major part of the reservoir area, is  considered watertight The insilu permeability  test of the soifs  in the test pits at the saddle dam site and boreholes  at the saddle dam site snows  permeability  value in the order of io m/sec Ttns value is indicates that the soils are practically impermeable
The alluvial soils  at AD3 and A Cm and spreading longitudinally  parallel to the nver Dedessa up to the upper end of the reservoir are characterized by  fine sand to sill deposits  with clay  These layers can be considered as moderately permeable
The layer below the soil cover at the saddle dam site was  also packer tested for permeability and gave Lugeon-values  of 0 at ADS -2 to 11 52 at ADS-1 At the other boreholes  different Lugeon values  were calculated According to the Lugeon test results  some parts  of the at the dam and saddle dam area require grouting
The  rock  outcropping  al  the  river  course  15  also  fractured.  The  fractured  as  observed  at  the river course are filled with chemical precipitates that it can be considered as waiedight
f
_______-         _ -___________________________________ SB Water Works Design & Supervision Enterprise
—
in Association with Intercontinental Consultants and Technocrats Pvt. Lid.IrjciDtdegai rrr1 giti on Project
GeoJ[>jftea! & GeotecluiJeal Invcstigaddps
5.4 Land sliding
_ ._
ju?2g0?_
Most of the reserve and a&uiment e«5» have gftntta stops  tajngrapty. Exceot Iht presence of some c];jlliss tn rhe reservoir areo, <*Q siqn of earth flow or slrding is nQliceatil? T he slops .of (he area generally  varies  from 3 to 3% wap! st the dam site ibutmefib Therefore, no hazard of slope failure, landslide W earth Row exists wlhifl the gro|ect area
Vater Works Design & Superrlsion Enterprise
Id Asweiation with IntarwnttoflndJ Coeiu^du and Tarfe one rata Pvt LuiPLASTICITY CHART
Fig 3 ■ CLAY SAMPLE FROM OBSE BORROWPLASTICITY INDEX (Pl) (%)
PLASTICITY CHART
Aline Uline
LLw=35
LLw=50
LLw=70
LLw=90
DHB
LIQUID LIMIT (LL) (%)
ARJ0-DE06SSA IRRIGATION PROJECT
Fig 4 - CLAY SAMPLE FROM OHENDESSA BORROWPLASTICITY INDEX (PI} (%)
PLASTICITY CHART
Aline
- Uline
LLw=35
LLw=50
LLw=70
LLw=90
MB
LIQUID LIMIT (LL)I%I
ARJO-DEDESSA IRRIGATION PROJECT Fig. 5 - CLAY SAMPLE FROM MARIBO BORROWPLASTICITY CHART
£
-Aline
- Uline
LLw=35
LLw=50
LLw=70
LLw=90
Series7 ATB
LIQUID LIMIT (LL) (%)
ARJO-DEDESSA IRRIGATION PROJECT Fid. 6 - CLAY SAMPLE FROM ATE BORROWDHB TP9             DHfi TP5 DHH TP ifl
DHB TP 12 -* DHB TP 11
OHB TP 17 OHB TP J
CLAY GRADATION
Awo-otoesSA irrigation project
Flfl » - CLAY FROM DH6MDESSA BORROW
PERCENTAGE FtNER (%)— MS TP 5            ------ MS TP 3          -t- MB TP 8
MB TP 7 -»-MSTP4
MBTP9
CLAY GRADATION                   ARJG-OfOESSA IRRIGATION PROJECT Fig 10 - CLAY FROM MARIBO BORROW
PERCENTAGE FINER (%)------AT08TP7 --------------ATBTP2                 AT0 TP fl
ATBTP6
ATBTP17
AT8 TP 3
CLAY GRADATION
ARJO-DEOESSA IRRIGATION PROJECT Fig. 11 - CLAY FROM ATE BORROW
PERCENTAGE FINER (%)--------- ATBtJ 107----------------ATfctW                       CMbTIN ------- DHB ip* -------------  Dhb FP «Q--------------- a.1B tpu
AlfiWi
ATB-TP'Q — CM6TP?
alHTDJ _<- chb TP 1
-- ----- MB FPS -------------------- Mb TP- J
VglPj
VI* TP ?
MB TP 4
CHA TP*
Mil TP
CM® TPS CMflTP*
□i^TPli--* CUB TP 11
O4 1P»
OG’PlJ
---- ■ «------» •----------♦
TO —4-4          — - « M—
50
JO
*
H3
ru 100 10
001
QON
owai
PARTICLE SIZE' (mm)
CLAY GRADATION
ARJO-OEDESSA IRRIGATION PROJECT Fig. 12 • CLAY FROM ALL BORROWS
PERCENTAGE FINER (%)BORCHA SAND NO 2
BORCHA SAWO NO 1
SAND GRADATION
arjp-oedessairrigation project Fig. 13 ■ SAWO FROM BuRCHA SOURCE SOURCE<y
PERCENTAGE FINER (%)* LQKO BROGE SAND NO 2
LtXO SE FERA SAND NO 2
• i-OKO BRIDGE SAND NO 1
• 4.OKQ SEFERA SAND NO 1
SAND GRADATION
F| a- n • sand frohi lqko sefera and
load bridge source♦ l-Cm$ QiniDGE SAND nC —H— LCK0Sf»-tR*SANDhO1
l-^cg BROQE Saftj nd s
—•-- SMCrtA 5AWD NO 1
i&tCi srrERA SAnD no 7
—KWCHA 1AN&« *
PARTICLE SIZE (mm)
SAND GRADATION
ar jo-dedessa irrigation project
Fig. 15 - SAND FROM ALL SOURCES
PERCENTAGE FINER (%)ARJO-DEDESSA IRRIGATION FEASIBILITY PROJECT
CLASSIFICATION OF CLAY MINEROLOGY
FIG 16.ACTIVITY CHART
PERCENTAGE CLAY GRAIN SIZE BELOW MMmm DIAMETER VERSUS PERCENTAGE PLASTICITY INDEX
ATE BORROW
CHEWO BORROW
% clay-sued particle? (*=0 002mm}
Pftqc IAFtJOOEDESSA IRRIGATION FEASIBILITY PROJECT
CLASSIFICATION OF CLAY M1NEROL0GY
FIG 16- ACTIVITY CHaAT
PERCENTAGE CLAY GRAIN SIZE BELOW 0.002mm DIAMETER VERSUS PERCENTAGE PLASTICITY INDEX
DHENDESSA BORROW
% clay-sized particles (^0 0D2mm)
Page 2ARJO-DEDGSSA IRRIGATION FEASIBILITY PROJE ^ ftnDROWS
TEST CODUCTED ON CLAY MATERIAL FROM SEVERAL
CLASSIFICATION CHART FOR SWELLING POTENTIAL
FIG 17 • CLAY ACTIVITY Versus PERCENT CLAY SIZES (FINER THAN 0.002m ,
ATE
BOH ROW
CHE WO
BORROW
Page 1ARJO-DEDESSA irrigation feasibility project
TEST COOdCTED ON CLAY MATERIAL FROM SEVERAL BORROWS
CLASSIFICATION CHART FOR SWELLING POTENTIAL
FIG 17 ’ CLAY ACTIVITY Versus PERCENT CLAY SIZES (FINER THAN 0.002mm)
DHENOESSA
BORROW
MARIBO
BORROW
Page 2ARJO DEDESSA IRRIGATION FEASIBILITY PROJECT
TEST CODUCTED ON CLAY MATERIAL FROM ALL BORROWS
CLASSIFICATION CHART FOR SWELLING POTENTIAL
CLAY ACTIVITY Versus PERCENT CLAY SIZES (FINER THAN O.OClimm) MARIBO BORROW • OHENDESSA BORROW • CHE WO BORROW o ATE BORROW
Q 10                       20            30           40            50           60            70           80           90           100 PERCENT CLAY SIZESARJO DEDESSA IRRIGATION FEASIBILITY PROJECT
ROCK STRENGTH TESTS CONDUCTED ON SHELL QUARRIES
AG 18 . POINT LOAD TESTS (SSD)
APPLIED LOAD ON SHELL MATERIAL AT DIFFERENT DEPTH
I-*—ADI
34?
LOAD ;KNftn2|
37? 822
92Q
—•—AD 3
LOO (KNIM)
Page 1ARJO DEDESSA IRRIGATION FEASffiiLITY PROJECT
ROCK STRENGTH TESTS CONDUCTED ON SHELL QUARRIES
FIG 1fl ■ POINT LOAD TESTS (SSDj
APPLIED LQAD ON shell material at different PEPTH
ADS
LOAD (KWM2)
724
15   ------------------------ *------------------------ * 16 -
19- 20 J
.o*o ■-■v*-.',
H2X
18
19
2D
21
22
Page 2AR JO DEDES3A IRRIGATION FEASIBILITY PROJECT
ROCK STRENGTH TESTS CONDUCTED ON SHELL QUARRIES
POINT LOAD TESTS fDRYj
APPLIED LOAD Off SHELL MATERIAL AT DIFFER Mr pEPTH
—♦—ADJ
■EM                     7»                      MO
■th
a-M                      M2
LOADARJO OEDESSA IRRfGATION FEASIBJLJTY PROJECT
ROCK STRENGTH TESTS CONDUCTED ON SHELL QUARRIES
POINT LOAD TESTS (DRY|
AfPLIEO LOAD ON SHELL MATERIAL AT DIFFERENT DEPTH LOAD (KN/m2i
«5
I
t
8
17 5
LQA0(KNAn2>
ADS 2
lCaCiWi.-
P»ge2ARJO DEDESSA IRRIGATION FEASIBILITY PROJECT
ROCK STRENGTH TESTS CONDUCTED ON SHELL QUARRIES FIG 19-UCS TESTS
APPUEOIOADOHSHELI lAATERrAL AT DIFFERENTDEPTH
-*-aoj
LOAD |KH*t2)
27736            23122 JA3W 26720
3tl»
-•-AC 3
Page 1
MWflFwmmARJO DEDESSA IRRIGATION FEASIBILITY PROJECT
ROCK STRENGTH TESTS CONDUCTED ON SHELL QUARRIES FIG 19 UCS TESTS
APPLIED LOAD ON SHELL MATERIAL AT DIFFERENT DEPTH
LOAD iKMAnZi
LOAD fKWm2)
L0AD(KWm2)
Page 2ARJO DEDESSA IRRIGATION FEASIBILITY PROJECT
ROCK STRENG TH TESTS CONDUCTED ON SHELL QUARRIES FJG 19 - UCS TESTS
APPLIED LOAD ON SHELL MATERIAL AT DIFFERENT DEPTH
— ADS Z
LQAOlKH^I
59136
64356
Fage 3Appendix A
Test Pit LogsAppendix A
Test Pit Logstest pit report
pit™ atebtp-i? _
X)6 fwSJfiLfJvQMiH!
SHEET   OF________________ ’
1
CLIENT
at watw
_
PftOjecT
Ang
CtffM
rngatKg
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Ate
UnffiMn
^BPI
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LOCATION i jTMj. E 343133 N _9JSKO EJttWcr. 1255^ AV.
r'T DIMENSION Ltnnfli 1 30 Mb
SURFACE ARCTJND PIT MBJiy **- ■'W*Hw «—*<
1 4ft rtft----- Oipffi I Wlltt
jOescRipricw
samplE
Symbol
DEPTH SOU TYPE
mti J
■WKluft menij-e -jr>n UM* ; rJ CW.
r«w
Sav
<Mn
ZhealTi
Ifft-
□ gw 0 20 Tap soil
0r W* moot left cry sfty r-ty -nr. 4qhh glW rooH
ooflm
D M tn i 10
AflSlGui i sitty 
c!ay.
F<m ns sort, red *rth wme Week loots, dry W meat 5JLTV CLAY weathennn product cl
r
bnMrt
2
2430
■3.20 Id. 13
1 W»130
Residua I sandy
Silt
■fc
dense                reddab yty
■rtrfl- d*fk spats. 3icul# n iMOi GRAVELLY SWO wei r*M* cliy (rrUflui sd4‘>.
•eaflirTing remnant of b*Mflc ijx* ^derr+ ¥^
‘SAMPLING METHOD     ■Shipping CONTAINER
B-Tt*W M>«
G-Shnv*
H-C*Md Stott
0-Tdfii
P-Tto
Q-Gi#M jw
Srpiastc
T-UleUiW
u-Woeden ba>
R<Wthbag                     Zoncaraed
Inwfctar _ ____________
% oggect^ *C*r< A
Accrete __ ___________
Dal*test pit report
PTT No ATEBTF-H
-CS.
rvriMJBcn
SHEET 1 Of__________ 2
CLIENT
PROJECT flrfi >?f5T» r-iaancn SiTE A4t yPairt. LOCATCh (UTM) E                      4       ft3295 _ Eta*»W ijWfT'a‘
3l« Cam Awe.L rf^ae
PH DIMENSION Ltnofi 1 2fl fiURFAC 6 AROUND PIT ntarty M
Wan_____ 1 2S mB—O«P0i J.llT-t
d.
'SAMPLING METHOD
fi-Thri wii lufii
3-Sha^i
■SHIPPING CGNLAJNE3
O-Tum
P-Tfl
Q-ulUt J ST
RulCfli Cig
S-omc asg
T-Weiji
U-W&atfCn hex
Z-ctacatdetf
Aflpi^ed ________ __
Logged ty Acer* A
dawTEST PIT REPORT
PIT No |MEBTP-14_
JOB FtwHtHi.aWW
SHEET t OE__________ 1
CHENT u—5ITV
c ACj£vT jzU^TJTTS? -wt™. STTF
.OWHCfl I'J’U E
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5LRPiAC£ R C U NO 1T ~d~j y "ji ■■<■;[■:j?Mowtfl.
CESCHiPTiQN
sample                     1            R«mv«
Kern
'mb 1
MNL        B pdnp rtiirt         moMwi.        F**        w*
,
rf          a
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otj> safer eHUip:. jr»n
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fkj 1
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wme -jraw *M3
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RSSiiJjya Stf* hrwrflb rw         icm* 1 jiify       Bic* w&. ffiwfi SJL"¥
CLA¥; «tfaD#n«g            af
■" ?                    &imK
: juo
3 TO m2 30
*1 ®
R<Jidua               ^ewr^n I’eecnr grty 1  s-an  try  '             '      -  ™^i   *
..            ytjw sandy SilT a-tp Ft*
■:^y iftWuii 1^1. «eafrdring irnwc of bawtb; r&s
izxiemcjrt";
-rt1   zaril     5CCtli               f
B-**r *K tuba
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C-GUr» sir
-fr-UPL-NQ^E'-CE Sn<'"N'3<:JN 1.L.£P
R-SiOi E*S                   Z l/icor it rj
mpecliy __________________ _
l9ggH»f' *0-1 A
U-Wacdtrt boot
AOCTove'l ____________
0*f Ufa atest pit report
bi two argaTP-ii
JOB Fwblift
SHEET 1 O
F____________ 1
CLIENT Mimwry -of Wjtwt BMOrfCM
PROJECT arw OrtMit WNiaosn 51'; vma* 'Jp?irewn *
cffi th* Own Asr
LOe*r>QNL"Ml -EMMS N
EJtyrton
»
PIT DIMENSION Length '50 TH A  oth _' :0 nr? Drttn » ’FT*
1
SURFACE AROUND HT nwetv Kt. tttttliw awMft.
r---------- i--------  DESCRIPTION
sample
■ng            £-w
i*g i              mL i
1 Symbol
Remark
□EPTh
l&CIL T^P : fHUdm  »*hjre jr*r i*ze                 1
-r
mis l                           MhCiy £■** iijrtocv jr»r
OfllcOlO
Top soil
Brown mew. son. Mty •:*ay vrtft SOgrass reels -o*g»fnc nrtflin
3 20 in i SO
Residual silty
day
Firm t«i stiff ■ed win S0fl"if piack s pel a dry :□ mod!
5iL*¥ CLAY 'M-aih« r-g
n
crcduct gf basalt
21
2430
0 20 i «
Residual sandy
silt.
Ceriw yt*iOWSb M0dn gray
f
1 90MZ IG
wth dltfk spots Z ‘CV-S: n $PW fiANCr SILTGRAVE- Aim !>*■ cay | rmg-jal scil1 *e#ih*riftg zemiftam d Msdine rack ifiWBime-atf
■^JAIPL NG ME’KC
0-Th.r*»H lute
G-Starti
H-Carv»tf Stack
^ShfPP*M3 CONINES
C^uw
P-T«n
□ Glass, ar
R-oalh oaq
S-fiiaw c 3*g T-Matal “in
IMVftMen Ms
Inspector
Lc^gmtiy
_____________
4
Apc^ertd ____ __________ Ctfe Mltrtfltest pit report
CLIENT KntWrr otlAftMer PertmtM
PRDJKT ftfrOWMMlmfliM- SITE
LOCATION d"M) EW70L h B3JH0 EimOtfi ~ -Zr. jsi fttpiUENfflOH L«na1h i^1m| . Wm 1 50 Tjj. D«plh t BPffltt
PiTho ATcSyp-r
JOB; FmMfrirwfflHtfTitM
Sheet r OF___________ i UMtwnttflrn ihg C*m Xw.i.URgifrt
J
;
SURFACE AftOUW Pl? w»fr Hat vKKjfwn cow«j
[OESCAlPT'ON
SAMPLE
Synt&al
Remark
C£iPTn
ml* i
5QIL TYP
□urucn/e rTKWturr ytn W* pwifcfv odor 5*r<. ywi
-/ee-
Nfi
Set
itoa.i
C«0h
fmt|
30(9 020
Top soil
•
B/cwn. rnotat soft Mty day tone gras? rMts -wg»-»ie
□r.jr.
L
Residual silly 
day
Frm io           rec wrtT tone b’acx spots. dry SILTY CLAY weathering oioduct at Basalt
2
2420
0 20 io ’ 50
1.50 In 1 ffljf
Residual sandy
SMJIl.
E
Onw yei-o^sn ivMiah yay
•Rrttn dart SCOTS circular m srape SANDY GRAVEL w*W ‘*\¥ day |-*esicuai sod i neither .ng -eninarrt of
>aM<K rock undtmaaCh
•SAMPL'ING M&THQC 'Sb PP'NG CCMAINFA
g-Thin-w Bube               O-’utw
Q'Sitaw
P-T«fl
H-Carved Sleek              Q*0im jar
5-0Hk dag
T-Meial can
U-Wowan box
R’Ctoth bag                  Z-dhscariad
iroSttifif _________ __ .
Logged Aberj a________
Approved_____________
Dote Ma. W
?cCUE*"                      LWvc/WmfHwJm
«K),ECT ly
uX*noN<unii E
rf Mflcn FjTF
MMQi-
PrT DMENSON Lencn I JO Tty A'flJi Surface arcu'jc ft? Mr. ^eartixm gwrt
CEfiCfllPTCN
C€PTH S&t. ^P“BJrucCufS r^pX-i» jrfcfi MG
TEST PIT REPORT PtTMs ATESTR.W
JOS
SHEET A Cf__________ 1
/-.Taj-
E4v«w 2i25UL“-
i 5C nva !5cpfi 1 3!'^s
SAMPLE
f Symool
Tye*
-
Na
■ ms i
=■**-: <v. ariM ■><«&*:,■ /v
Ermwi           so* ufr rtav wif i£mt ijtjih, rMS -er Jiftt:
kg.)
C-*SUr
Irnt 1
0fl!o3xf Topsoil Gnom
Residua 5$fttn6rm
i - jN              bi*:* KO3 9 gnty
r           <Y ELAT. *eathrTTff
'
C 25 » 1 2C Cla^ product cf bMM
Re$KjuJ C^rfcf
21J0
3 25 :& 1 2C
roddafi irfty
1 sandv da™  ’=fCu4f fl
7 5/iaoe SAW 5lT-#di re*
S,rT
ray                mH!. «Jfhen^ tf fTWlFf DJ3*«£ ■*KJ«
i 20 to ' 15       ”            unmraaffi
-$AMP_ VT vE^CC EPPING CQMTWEft
S-Thn *al UM
-
O‘Tlj£w
S^ww sag
ij^Shcrrtii
P.Tm
T-Mnl
iH- Carved B'Kk
C-^jiasi ar
;
U-rtCMtf boi
R-pcth e a-g                   Z-tiKVCM
rtpeeior __________________ _ _
legged Cy J-era t
Apprised _________________
Dsn jjiw KTEST P!T report
piths aTE9TP4l_
B cs
wnMWtf*
sheet " Cf__________ L
oiewr ^toJl
rrt£  _R
J!      Q2L!TQ
fRCuSCT Ana Ccat-tM r^y"rr e.'E A<e*Uae. L^mn 'rnm T*Qyn to*Lrf?>3n LOCATTOhmjrUn Et**M5 n 335_l£±^'LHt
W CmfiNSKN Lr^r : lo-n& ftiarn i ?i Cw? '
5-JKwze AfiO'JHO PIT rw**««c »WBtWX1 KWH
CESCAiPTFCiM
ED-, TYP^irucirf* Tciiirt g-*f we
SfcHCti1 actor Mttttr
SAJUF^e-
Symbol
^errark
1
cepth
In-*]
True'  No         &ze         Depffi
i*a
rtm 1
grown nn*5t 'sGfr. i*IY£*V
wm wrrtt |)fj*s co% -orgaoc
r
Tap $Cul Qrgi-.
_
. a Illa 1 30
"i.esidLS     F^mtcs^     trownisli     i*rd     **T< I   |f„           «mc £p#c* wen. «y 5U.Tr
Sj
CLAY, w#«nr«g pr$»duc1 af
■          bMjfl
2  :.i2o        0 25 :d l JO
>1 JQ
1
ReSKfoia Ceme/yeiGw^ttxii ! 3^7
1 sJfdv -*0 ■**** M,:a- ertcW
T ^weSANOYSV-rrti'wr
C=xr iretaujl Kd|. weatfiErwg
remrart g* bHtt HgK
irfrtemnffi
■SAMPLING MET^CO Til--
20^TA'Ngft
0- Tbn w«i ?j?c C-Sw^ei
Q-Tudb
F-Tzi
S'ptasbc
T.Meal zii
H- Cjfrtd Sack
□-Glass ar
;
U-UVaocen toi
R-cW hag.
i^CKicr
__
AflCra^C _________________
Lc?q*ccv Abn ■*_______
Off' WBv QgCLIENT MhWyafWtiwRtMMlWHi
WCMECT Afltp«^S4a vnjatrcn SITE. flHjftW,
TEST PIT REPORT
PTTNff. A7gfIEJ_
JOB: Fea^Wv investigation
SHEET r DF_1
Kapjt Darn A"F.L=*t«l?
LOCATION fLT.W; E 244-15t W CjJjO Etarttfati 14»n kJ
SIT Cf,M6NSlCh L*nrt. I CK1 alts \Vdtfi 1 w TH5__Of plb- 1 90^
SURFACE AfiCXjNO PIT nwrty !L>L wmttWfi
I-------------- “
■     DEPTH Imts/i
J DESCRIPTION
SAMPLE
Symbol Rgmgrk
IsOIL TYPI
dmidwe -no^rur.                    we ctoXrtv xXr fclim
Tn-’
“NO
&ze
Ikgi
Depth
(nM |
a0i»0.3fl
TOC SOil
Brown. mwst, soft, silty clay wtfi some grass roots -organic onpo
■ii ?          'T
-■< ;■
0.M Mfl.90
Residua r silty 
clay
Fem io sitf 'ed wrth sor>e Wack spots moist SILTY CLAY weathenng product of imaU
2
2430
V W rod90
r‘
r'
t        ;*■£ r.         ix.
Resichja I sarxly
D?0 Io 1 W
Dense ^Icwrsb redrtsh grey with dark scots. ctroHar in Shope SANDY SILT wrth few cuy I residual sof); weathering remmanr of basaltic rock underneath
* ■        ns ’.5-J
■-J
■gAj^PL NG METIOQ POING CONTAINER
S-Thnwal Sute
O-Tufre                             S-plasSc bag
G-Shovel
P-Ffi                               T-Metai can
H ■ Carved Es&ck
Q-Gfass jar                    U-Wooden bos
R-ctoth oag                    2 dseardeu
krapflGfar __________________________ Lugged by: ^efa A
^opnjved_________________
Calf UfiJ*TEST PIT REPORT
PrTto argans
4CB Few*** evMaqaonn
SHEET r _ OF 1
CUENT
*ROJ=Cr Arg ->^1 r-^L
Sire fli Tf*a* JOTfrBBffl frflm tig cum Aaa Jjfrri*
LOCATION   rUTMl   E2u._545
N
_
ffiijfg EJwftoft l4O?m «r
PiT DIMENSION -<wi » 55
_ Wctb T SQrnta Owfr 2 9OTO
SURFACE ABOUND PIT
fl*
Wynd
CEsCfliFnch
DEPTH
i'mii
SAttRJ
| to Sier 2«tb
<ka i            4mtl
Syrofii
Rf*fl4TM.
sot type prj^u'fr rrofhzi jr*<1 **»
clriDei*. ado SiHr^-E .- ^fW
Ewv 3   3
s
1 0 fl I n Cl a
?op Mil
ar*m .tWL 14ft. WTf c?ay
»nj- afire# grata nets ■orgw'G <*Spn
L
f- -■■ - .
rM
L-- ^;^-
tEfitJiSi
0 30 10 1 W
Residua * Silty 
clay.
F/tf to tiff, ran *ih acme
-
mnotSILTV
CLAY wMHwr>S pfDdUCT ?’ baaar
2lW£
fl id i 3d
-■ ’•■ . \;5 i
: .-■ . <
leowzwl
Residua □e'**. re’o**11 ■e«T^ sandy >* =*"**%
ahape 5AM3r$ILT *rtfi tea cloy'frAfroji Mi\ *eatbm^g
art of trSaJ&c rtsck
•■            j"derne-iC i
s
"SAMPl.NG VE^HCD 3-Thn *n tube
G-ShQNfi
H-Cwwd&QcA
■SHiPP^G CCftTOjNEff
O-Tube
P-Tin
C-.Qew jar
S-ntas&c big
T Melai can
U-Womten &oi
buq                 Z ■aacarcz-d
nspectcr _
loggrt
A____
Acpovt: _ __________ ___ E*e "6
t
I
ITEST PIT REPORT
J- T             ’
<—*■ *Jf* -j Clent MnrtvrfWjItrRrwt™
PIT .Mo A»EBTM__
,OB
n>*y»Wcr
sheet j of 1
’lOjECr MP
*-UQcr SITE fluUci UPPW!3! jar
LGCATrOM(V™| E 2<j^i N S3&35Q SmBcw jii Bff tf
PIT OlUE^SION .enjr 1 W rft Wfcffl ; AC frra Ow-T. 2 4frrtt SURFACE AftDUND P*T rtfffr flt.va-jftfn PVTl
cescriptcS
SAMPLE
S fTEd
p                        RefffMk
T
DEPTH    SOIL TMP
— 1PWW  '"^Wf jr>"i «4»
;inb: r« ode-
"C4M Prcvji TiM! toff. t*ty ,d^r *tii rane J-’®t oni -
Tjffe"
Na        Sa 1kg 1
Dap*
IfflLl
r
OCtnOjO
i CJ Ril erganc cngfi
Residua Frm, icd *fF K<-e Bac>
'■
[“hi-l
I
1
92OU24C
aiHy              ipcis- e-^HX SIL TV CLAY weaCherrg producj oi baaat
2
2&3O
0 20 to 2 40
Residua ! sandy 34't
Ce^se yefcwtsn ftcctffl yty wTi dark toott crcilar n
$ANOY SILTY GRAVEL
•rtfi few na> ;res«Ou* icrfi wtfTerjifl emrort cf fcasarc roc* ^emir
>2 *3
1
‘5AMP-JM1WETW0C    +SH1PRNG CONTAINER
*jf tLfct
O-Tube
S crtastc nag
G-Shnre'
PTri
T-MeOion
H- 3an.ec 6cc<
Q-G»» |8f
U-Woo^tn Mi
R-com bag             MciM
r-Tp KKh _________________
r
^'^•d_______________________
L defied &■? Abera A
C«e ViY J]g
. ■* 1 ” . L jf□ r* «.x_
*1
*— ■
2f»i> KM "1
-w ' ‘mt
'■__________ -J
*_p<irr,rfe
: /**
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F"t
r .' -Il I *: rjp ICM
B—- —
J   < c           1 K-* ■ 1
Rri -JuJ Hff
r—i it
—n
■ rj
1dw?
"-*n
-r ZtfWdfott
qj-ct
p r ri
1-p.jpLX 0<ag
T-JKM r*i
; -Jmm _■
■3-ckrtT’ ~*v                 2
^4Wn =^»
TOrtf ________________________ _
..agfjari 31
1
. «LxTEST PIT REPORT
PIT nd ATE3~~-3
job
SHEET _! OF_____________ 1
CLIENT MWr of Wft»r Rtta/ctf
PRCJECT .Mo
lOCATICM ;UTMl E 24X17C N
(
mgjicr SITE Att v4aot. LW* from t* D»m Art.Utet 90SA7B EWvaftQH M>7m aei
P1TC1MENSCN           ^trqri          ‘          2C-Wctti          1,50           CTOtn           *           lOmtM SURFACE AROUND PT r«yfy  at_ yeaptatop. rgweTO
4
i DESCRIPTION
.-------- ----------- ------------
SteKi
Swnbtf
Rarr-anc
DEPTH IsOC TYPE
tUfMdhft -OrlTu1* flfir MIt.
ptMMity. m»» Uatarcv 'fw
Type"                   SlEB           Cep tr> «. :                   fmlii
flrcm. ^c<v writ t*ry dtp tome $r»i ana ciarc roots c rgartc ongr
—
OOtoOSO     Top soil
Residua Fem » wff to *»tn «-*»• :**:*
il Silty wea wySiurrCLAV
*er."»e v»j □ aCuc{ ert Dasat
r,
0 50 la 1 10
2423
0 20 :p 1 1 cl
*1 rfl
Residua 1 sandy silt.
!■
OrtK.yflawTW tow gray wrfn cart spers crojar <i srap« SANDY SfY GRAVEL -*Ti few day i/esduai stxl wtatTarng ramnirt of casite rock undame an
'SAMPLING MET.HQC
0-Thn w«i nx>a
G-5&M
H- Ca'vea Qtek
‘Shp^g container
OTuba
P-Tri
(MStea jar
S-piaw p«$
r-Mtfil
ij-wcoden ban
dag                 Z-sncarfleO
iraoecter .
____________
Logped ay .After* A______
Aewovej_____________ 0«t» v-n fraIO®
TEST PIT REPORT
ATM!?-* .
3
M=F7
'C
F_________
1
CL'EST                          j»Yjler
Sirs
AWWUM
Up
dTMHTi
frflffly
Otr
AfflLgftfcd*
,      QCATK3I*      [UTWl      EWE      N      —
935557 EfrvwW i*i5m J*
PIT OMEvSlCN
075fnfc _ -Vhir
1 Q5_rnB Onffi 0 Wma.
SJffPACE AfiCUND PIT ftWffr ^C*c*oy> C J*W3
CfiKJW’TlOi
saiIple
SrrrKti
flerwH
r*EpTj«
fl-™, i
SOL ■^PSHFVCflXf. rrwMWt
*Ua
Type-
Vo
rliiscfr MlP* jLJwnc. r*"1
StOTi
Imtl
0 0 tn 3 10
----------------- 1---------------
Dirt arown -ncnt 3^ fl.
cay wrh                          ■‘Mil - Topsail AQitw ongm
IQig 10 3M
RejiiJua   Frrn   Id   J5fl   -*Sd   Mh   some 1 5lltV           t*** 5Wfis n™“ S,LTV
Cunt -#rtr*«*g iiedbc!
"’*■               :™r
Residua
sandv
7
h     mp* SAWEY* SILTY GRAVEL -rfti lew z*ay itffMili K*X
n
weilWWIQ ri-xwrc ol tjasafr:
>0M
■SAMrliNG METHOD "ShiMinG CONTAINER
TVi wil !lE>*
Shmei
C-Tufce
P-Tfl
3-clartc Di?
T Melai ran
Caved Beck             C-Glasijir Ri’lcr bag
i%JKtCr______________ Logged by ^erj A
dataller &ai
Z-dsnrtitd
AflXWM_______ -arte May EftTEST PIT REPORT
PIT       Nd        ar.EBTTM
JOB f5jfrh.it-,. ^-ElbCJjlDn
ShEE T 1 OF______________ 1
Client
tfwror flasourcfa
PROJECT Ano 3awu imja*y 3iTE Ar* «tljqa. Utu^fyn Tpm -tin
LOCATION UTMi. E 2XAHS N                      835<ffl Glwbon 1ltgm at
Pit dimension Ltntn 1 4? mrs Wtoth i.4C.n B______________________________O*P* 2J2H3.
ax.5.
x
SURFACE ARC'JM! FIT rwtfrfcrf
1
DEPTH
■ma i
■DESCRlP’iON
SAMPLE
Symbol
Remark
SOIL TYFEirrMctyra. ,-wndurc jran atfc
^nboCV                 - iUd*TKT|< jma-i
^0
r
1*9 *
Depth
fmlLl
0.0to 020
Top soil
ETgwti, Tios? m* silty wdTi wma arm re« -or
engn
0 2C Id 2 10
Residua 1 silty 
clay
i- rm :□ sSfl. rad wth »mt black spots, 5-tghQy mcist 34LTYGL**; wwtfwftg
product or basjht
2
24M
a to »2 aa
Residua 1 sarxty
s l
□arse yeltewsh Io redn>ah
fifty MrfTh c*rh «ifcls. circular n sMape SAN0< SHI wflfi
day fresduari wl)                j pen ng fem^arr nf ban-attic rgcJc
>210
■S^2illiG M£ZMCQ ripping CCKTAiNEP
0-Thn wa< lute
O-TUbe
S-piastc tag
G-Sbovel
P-Trt
“-Mtlai can
H- Oved Bioci
U-S-asi jar
U-WflAdM bate
R-dflft bag
Z-dlKaHted
iMpMtaf ____________________ Lc«*d by aoera A__________
Approved _
Dm .yw C£
HTEST PIT REPORT
PIT
No
ATEBTP-7
JOB
awCET 1
gp______________1
CLIENT MhrtVtfWMFRBMTDM
^C.EC Ma JfjMsa ginrtcn 5;7j
UcjUT
MT,*nm Jig Dwr.>CTLj^t
UOCATKMJdLrtHi E 2M3« N -Bi
jl 1 EJW
WO '■1Zlm WL
PITDwENSClN Len Ji-
", ip
Wu» I ?J mja CrPtH '
SlMFACZARMJQpn
jhMwc<h*m
L'ESCRiPTlCh
SAttf.E
SfrflM*
1 OEPTh
. J™!1
SOIL TYPE
■yjtrj'ii        rra-mrt        gwi        m ft MW *7. ■Mfer Sf4^<V 7®*1
TW
Nd &es
ikg'
Deem
i/ntl
RennfeB.
J
H-'cwn  [fry  s-:*.  s-fly  ertav  ^Ti wmr yaw f«S
OOta a 20
T ap soil
20 la 0 30
RenOua 1 silty 
clay
Fwrfi !o tffl. *f 0 *ffi «rr9
biKk
*Eatbenng product -:i* Dass?
2
243C
020*0390
RfrSlduJ □■nw.yetawsn recdKn gwy
“1 sanCy
'              lie ‘ew clay ift&gbnJ
weaDen-Tg .’CHHiarit □! □suite
3 M la 1 ID.                          >§«*(
C *3X,B'
K SWOYSttMAWk
!
------ —1
SAMPLING METhOC            ’S^|WjinG CCN"  *«K
9-Trw wal Ltt
G-Shmd
H- Cwwd 0hft
C-Tuhe
PTn
Q Gism iar fl.-de IF b*g
5-dSVK OdJ
T-WttU »
U-WWSffi fics Z-<HCarSt«i
bipeclcr _ _
uoofd« ___________________
*p-|>«r-ed______ _ _______
Ma              Lfitest pit report
P'-mo ATES-v-'
SHEET___!_=t______ 1
CLIENT             hnrtvJWMr             AcwC** MWaECT A-:o D*J«m_n-€K)y
Te O»m AwaMtHiOt
i.OCABCN(V^)
AU tW£'*SICf1 L*r>rf, i_W mis
.*_
gitg Ay rfw
KHlM S«waW mirt-m
A crt1 t MN-b- Ofitfi '07!t>
SURFACE MQUNC P-T n^-witjfH^rycn
DgSCRiP-iCN
SAMPLE
SyfflOCi
Atm art
DE°TH
■!mti i
SCIL TV^Sojipyr                 wnptfBreyiM"»<y rtvcfb'l- I-Tvoi-IB 3TrH
1
(MK4 gdo . ->W<V IAU ^mpdrWXfl.Xijn
t   Ei
,^
Mu
SiXt
<kfil
|fTl£ j-
C 0 in 0 25
grown. notf wit arty c>
we’ MnM- grass tk£i -tfg
Tgp SOii
Residua        m t&ff,                          sama f gjify           b K* 1049. HKMt SILTV
, ,                 SLAV    wtarhmg ^ducr flr
FrTT1
025 taOW
w-      w
2
2*30
0 25|dO.K
RtSldUl                     yffcWHth rodUAH prev issndv “*■ “**!pch- amJi' *•
f^ape SANDY SILT wfli
ktejr .iwduil »M) MftMmg
•Emrrant art                 .«k
ft 85 TO 1 <0
’SAMPL ING ME~HCO         *SHPP*NG CONTAINER
3-Thta wai Tibe
Q-Tyte
5-D-Mt fcafl
G-3-^mH
P.Trt
T-Mtia CM
H- CVwd Start
G-G4AM
U-Wncden Dfisr
ftcMi&tg
Z-discarded
inspMW _____________
AfU'^ed_______
L3JSMtT At«ra A
Oiftr M*, ftTEST PIT REPORT
FffN»
joe         fsfssiiszjsraiHesc 
■Sheet • Of_________ i
g-iEhT wwvrfwtf-mrH
PSCJKT Ana 3aden.T* :n^»nn SITS Mjn&c LW»W *0^ fl* Aw* Rtghtede LOCATIONruTM;. £30271 N 92j22  E'wanpn Wi»l
PIT ClMENSCN. Length W<". ! mts 2 ZfrnB, SURFACE ABOUND PIT ffiBffr M WWtHW CWWld.
T
S*MPl =
C£PTH
■ ma I
DESCRIPTION
5CH FyPK "-W-                 urtflWKFir}---^-. lirytfint       ffWrtirt.       pr»r:       *£* p«l^       Wt*       SurflmcY.       QW1 3H*W OTTOM-i**" tTpJfi
Symbol
ft j mart,
Nd
Sar
lfcg.1
Dtpto
(Anti
0.0 to 0 10
&twf.     W.     W"L     WTr wme 9*au r jces -^£jn.c
T$p $0i| q^pn
Res  -Hua  F-4™n  to  Jif*  rnj  #r.n  some |   fty                              b*M« men* SLTV
Sl
fl TO to 2 2D
J
. _                                  GLW. Biearm^ POMT or “■*                baiaJ
2
2£Jc
0 70 fo2 00
>220 |
Residua      CeftSe.jnHiSwVi      Toisb      grtv IsandM                           ***■«&** ri
ihapt S^JStDv SZLJ              rs« 4               ciiy ■ njsKfcjaS mJ! wiilihtwigi
rerrwnant  cf  tusaAc   roc*
lummar
“SiAMPL'MG WETHOC         ♦SHIPPING CCNTAl^^
0-tm hH !Lt*
D-Tube
S-0astc nag
CS-ShMi
P.Til
’-Ve*ji can
H< Caved'Slat*
Q*Gau|v
U-A/oaden toi
R-clato Eag
2 -Ascardtd
IftSCtClor _______________________
Logged Uy a
^craved_____  _____ Oat* Mar/ qgTEST PIT REPORT
CLIENT UtMfry af Witer PROJECT Ana DrthMM^Bftthon
SITE Mantw
LOCATION |UTW E23J15* N 931835* Ei^rafi 135ffm *H PIT DimEns^. ^enplh 1 5D mis Wiatr. 3 53
PIT Mo MBrp-3
JOB Ffii'OilCy invf5Oqa1icr SHEET ? CP_______________ 1
VWffttfft from iM Dim
___ 3epn 2 70ma
SU-RFACE AROUND PtT
*-K_ rtWBM cqwd
!—
CESCRiPT'C^
SAMPLE
SymdOi
Remark
Depth
4mis i
Ln np-
■nctirr,    ■uoTuni    -jran    urr Jfcfcfr. «<■. eiHv^v. -jraei
W
NO
Siza
fkq. ■h
Deem
mt)
I
C C =<i U . 15
Top soil
Biewh. mfifft wft. miry day wflh seme grass fotfis <fgjfne
nngm
\d
-
d ria 1.M
Residual. silty 
tlffv.
Shffl. OmHSfti r*] :a me
■nc<ii SILTY CLAY. Mllher.fig
1
pr&duil Bi  btuM
2
0 90 tot 23 1
Resxfaaij sandy
silt.
if
rMio2 70|
jert«.yeilflwsrt recdiy firtiy dJwk apois arc Jar .n
Uiape £AN0y S<LTwrth *e*
:lay i rotdyal 50^ 1 ^alher-ng ffrir-jni or t^saiBc rat*
indMMMh
■SAILING METhQO -SHiPftNGcmTA^heR
B-Thin wall tvw
O-Tuie
G-Shc^fl
P-Tto
H- C«¥fd Block
G-Glass.ar
A-dClP Ci-jl
S-P'ssne d *g
TJblrtgl -7jn
L-Wo&den bee
Z*4iKSrM
Ifflpesfli' ____________________
legged By Ate*a A
Aporcved_____________ Date Mey 36TEST PIT REPORT
PfTNc MfilEJL-
jce
SHEET 1 Of____________J
y
CLENT MogTr 0^                     Atyx/rrq PROJECT AncCtonu .-nangi
SITE. MinbaWUm Jnfrwn frgr mt Qam A^ Rigrs**
LOCATION |UTMJ E 23XXEL- N /Ift/fT rkvtuxi
PITOME^SICN _L5fiUS> W«rth 1 $q>fi -Defy, &.*&*!.
SURFACE ARCUNO PfT
DESCRIPTION
CE?Tb
ima
&OHTVS«E
aruea* « h*>mww yi«" m* W
pouc-fi* sdw tMMsnc-* j*M1
SAMPLE
J Nd □JH Oeah
ikgJJ            rm I
S/rW         Aer-art;
Q Ok) 020
TwwJ
.
Brown. rnertt                   :!*, wih   K»r»*   grw   to«>
rry
RendUAJ Ftmlo-Mf* tm *rotfr$K.TY
s4ty day P* we«dWH> pttMufl of
L <4**^
fOLi
■- j-rx*.
F — —
r xnnnr’i j
.-■^i”"‘i.;: ■
Y
5
020 ID • 90
■ Eutue
1
2
15
I
Re^dual                  yt*ow*sn mmt y»>
mVi <Wk l«cts fcrtuUf rfl
T ir*e* SANDY SXTY GRAVEL
**-               wC V* City Irwtfbsl MHI
wwih*nrvj     -F-j-jrt     of     bSMtC
rort uxle'neatJ"
1<0 taMO     L
’SAMPywg v£>cc      ♦SHAPING CONTAINER
9-Dwi ■«£ lugM                  O*Tut«
G-5hcr*H
H* C*-*ed Strt
Mta
C-G4U ;«r
A<Xtf> bag
S-WtC 5*3
T*Ms« ~an
u.wooa^>cn
Z^lcarM
npedor ______________________
Lawed iff -tan A
Approved_____ ________
2mTEST PIT REPORT
CUENT.
PROJECT
nurty SITE
PIT Ta MBTP‘‘ _
jca
5HEE’ OF 1
y Fjsa.>agW>1 Itt JUjyi
iwnoatUTMi _£JSM»_ N —fiEzl. B-**" •«=*
PIT DiME'fSiCrt. Ltrffi-. I 5Qffm ■‘■‘<nh _. i»Tt> ,2W
SWAGE *MusD PiT: <w vwahen iLs*j3a
' ?<^n>
Tdescaiptsc^
sample
SymCO
Aernirfc
DEPTH
■Wl. I
EOIL TTP
■fcd*W               cnrcnJ&Brc^ dirtily 'fpe' r.uuAn                            gi>n pin
'OHfaper. rfcr diMrey flw>
srrjtfl
*
floe
Afl *
Zwh
«t 1
Resume
bUydsy.
OMloGtt
lEtni Ti-ff ne. -tm SiL "* CLAY. mffwrthg redyei
buail
I
2
OttlaSTO
r * -          -J tTv>-3
pj? —tr.-s ;
Residual sancSy
Cvw'ffWt «:r|h je*f
*Mch dart sp4h. ±r?"jdr *
va« SANQV <V GRAVEL wth iWw rdy *evda* w<i
w+aihtfing TOTw-arri erf ta»4c nxk j-tip-keafn
0?<ltaiM-
“SAMPLING WE THCO “SH’-DPiNC CG-M7AiN£P
S.Ttwi waihri*
S-S-Mve
Mid
P-Tft
a-flilKT i*?
T-Maoi or-
X- Carved Stock
Q-GdU*
j-'Amxj#!- bill
R<Jdh M4
Z>dKartirt
ARUM* _
Lagged Sy Afcrfr A
Didtest pit report
P4T fob MB TP-7
JOB =taygg¥
■SHEETS_______ OF______1
PROJECT Afifr CWdfrfcg* -□CAT|C+Ji;UTM| E2SXB6 pit dimension
5-'TE fiftft? YltlBBi
'.337912 Efewowi iJffr^Ml
" l^Tjrg1 <h*
isq^ , w-sm ___________ 1 53mi*, ^e**1 _L2*^
SURFAC E AROUND PrT. ntrtriif *t VABlman cgyral
DESCRIPTION
Sample
Rernift
DEPTH
iffltli 1
&CIL TYPE
(KflailaroidwiMy rammi'B                              gra** M*. frMWtf. -9dpi. di-trwrr
htwH u^eeMKn gw
prjw
‘■JO
Size
□*pih
liTTl 1
Rgjidual K"™ -°                       *  SILTY
r
reti mc  si
COOtoOTO
Silly clay. !eb*y- w“h*n"°
tawfl
1
2
OSacaOTD
OTOto' 30
Residual sandy
stt
J1
Dwr’M     ^kA*5n     iKfckshi     gray Will      tfiA      m™     CMSuiV      H sraM     SAAIPY     S-LTY     GRANS- wiih -few Ay                                sei) Rreaihe*inq np-71 i-ju^J tf CijnJJ£ rockuntarAft
■SAMPLING METHOD
fl-Thn *a»i tube G-SlwM
G-Tute
P-Trfi
SftiHlK./*?
T-Mp-Ji Ci«n
H- C*rwd etock
Q-GUm
U-WOMtefl tMK
R<tcihb*j
Z-dbM4JijM
inawctof ____________________ _
Apormd_______ ____________
DA a
S-ITEST PIT REPORT Nt MB ^=*4
§f«7_ 1            . CF.___;
clev LirrTrrrrrnimnw
kO&T'Ch■ ,.”V ESSCSC ■M __
_          _     . , ._ ._
a
"3Hbw ■*
a fT 5«SNSfiN
“ K "B War _ Tx-fr Z*nh C ~7T*
C=5Z=?F" Ch-
Srw
MFTH
fln-i
SdL">F2
'fTdGJV -DO&F1 pr fcf«
ztsabee, XM* TWnCY Z*'*
V-JC* ==*-pc«o- 3«p
** 5^>
<5 I
2«*X"
‘Sf
E.TTwn. -noal i£fl MTy C»y
Wd »-< jrw <*$•«
WTL<C
30b an    Teo sol     or^r
Restful
wnC?
sit
-X*l
ci5®gra
"SAMPLING ME7hC<D
E-'nai waJ i_«
C-TlO*
5-GHKK Z*£
s-t™
P-Tta
" Mr-Ji i**
H-GtfW = ■*>
L-A'xde* X?
^oanxe
Z-iscaried
b
i *5*W ___________________ uw**f jtesxA^—.
=«TEST PIT REPORT
PIT Nd
jOB F^a^bnty ^^SWfllcn SHF.ET ,L. OP____________ 1
CU€NT Mrirty flf Wrtar fftwrcn
PROJECT A-io 3mmm Urnahzr- 5-TE MrOo rfw UkM^ ** 0*^ uOCATiQN |LTW gMOQflt M CTW flcvJW iMZrftff;
a lTDlWEhS>Qh LfOfft* 1 frJ'nfc . 'sYkW 1 SO mfa E*P?i g
SURFACE ARCUNtJ PIT Ttarfr                  «W1W1 WOTtf.
DESCShP’XiN
iAMPu?
Symijcl        Rwiatr:
GcPTH
■mis 1
&CIL PPf^*«ncmsr- 4fFLrr
r
monJjr» pr*m U« PMiK-tr “**             ******■<-!■ Df*p BhK* coTtiMW onpn
■Type*
■ND
Sire
Ml
Cwth
IfflC
ootocnc
gram, JTKrtt MR. MF|i
iwffi «-Tie yin r«m -qrgtw:
Top Mil I^ijn
QMtoVTD
Residua I Silty
day
Frm Srcivr+sr red, nioT-l SILTY CLAY wtp few pfcnl root wtartrnpQ pradud ar1 btl*l
2
;i3fl
0 3Q So ’ 70
Residua sandy
Silt.
1 70102 43
Drat yelcnvan reddth tfeyi
wk iooo dnlv r
SUM 5ANCY $JLT r<w O4y ■'tt CL JI Hril: -ffltifwfirg. rfifwiant d tmtc rock iroerneaL*!
"gAMPUNfr MgTHCQ
NS CONTAINER
“■Thr wtf tUbf
C-Tuoe
■5-giuSc c-#5
•j-ShGW*
P-Ta
T Metal can
M- Caned Bi&ck
Q-£i*»iar
U-Vicaden oat
R <idPi ts»;
ZtOBcartffrd
irwOKWf _____________________ Lagped Cy AftO A
Apwc.td _
Cut 41 av JSTEST PIT REPORT
PIT Mo MBTPj_
.oa        2-? z-jaH*™? sheet 1 .SF_______ 1
CL£NT
.QCATION       .’UTMl       E25C41J       .M_ ’ITDtWE'OSION Lenjlh _jJOrn._
SL’^ACE ARCUNO PIT. -trv X -rotWri
537SB< E.^flm IlTfr^JJL _ZitiP i.gOnr^
~ 7P<m
5ymt»       Re-narx
DEPTH
nts
C^SCRlPTON
EC<L Type jcoo-r. wne«tmcyM*i*ty.
l*Mhn "wifiz* P*n w1
V M4 zcrrocafc* 3'■J*'
.Tjpf
r
SAMPLE
Stan
ifcgi
imU
DOtoQIS
Top soil
flruwn iwa, soft, sty cwi
**b Kjrrw $TSSS M>d PCOtS ofpmc QTgn
Residue clay.
Orn «c |Uft SrawrrtH ea to
-
-M nwnl $41. TY CLAY wutbcnrtj praoucs cf I»ut
3 15» t TO
2
;&3o
lOOtal 50
RwidOBl        -*’4*        .*'cwV        *»•"        4<*r *** CO* *°*1                           c*cv4*‘
y                               SANDY SILTY GRAVEL *"                 arih **- day (wAal sod)
-eilhe^                           a* basafcc *            rack untfemMib
*»70
•SAMPLING M6THQP
“SHIPPING CONTAINER
B-Thrwoi h£c
O-Tube
S-p*<c G«g
p.trfi
T Mm rar
H» Carxtf Stock
Q-G-4M *
' l-'A'ccdsr sen
R-cWwq
iftfCtcfsr ______________________
itwo Atea-S_________
Z d-scar red
AftMTTMtC____________________
Car* May ObTEST PIT REPORT
PrT-'Jo
JC0
KTt<jeflinon
client lantvorwi^fa——
FBftJGGT
LOCATION IL'TM) 5 250547 N . W DIMENSION Len^ui -~ ;
SURFACE.afidUNDPi'T neartv
SITE
3j»W- E rxnn
SHEET t CP_______________ I
Uwtreim frcm ti^ &nei Am.WWifd*
: 50 n^t >Vdh _ i 50 4Ta J_5ik2!i.
cjvrrrf.
JDESCfflPnaw
SAMPLE
Aprw&cM
BERTH
■ms i
&CHL TYP1
= C8kMC            ati-^rWWy.OtwKY
No
^■JE
affu=aj*t
iw w*
JJlPKrtf odor -MflKwy. flFXi WW Lij™i»*o--n pigpn
n-r
_____
&OW020
Tgp soJ
Brown rnont wit pJty slay Wdh 1OT* flflU rocn onjjnc flrtgpfl
Residual
Silty clay
Fam. Brown n ed. monfli
r
a X> io i so
6
SiLi * CLAY. watiianng prwJud or hauT
1
2
1
1
Residual sandy
H ft
,       M50
i ttowTsr fKteoh flrep Wrth 4*>h H£a. titular r shape SANDY M.T «*ri tv*| cov rre«1ual w*l. weairerihg r emnaN od Msarc rock u/KMirwjdn
“SAMPLING M£ThQ(     } ’SHIPPING          Ccntaineh
0-Tbr *ili kce
O-Twfca
5 -Gl*»hG 5*q
G-ShCrrtJ
P-Fhi
‘■‘-Metal car-
H-CifvnJ Btoih
Ci-Glu&iar
J-jVijQien Kik
Rt-aan m q
c r^rt4*Tiej
Inspector
kwdbr A
_
___________________
Afrfi r^-^i __ __________ ___
Ou. 4!±lQQTEST PIT REPORT
PIT Nth MBTP-;
JD0 ■
SHEET 1 CF______________ £
CLIENT My^ry Of Wif ft«aEEg
PRC-JEC" ^naC*WeMalrr-fl.Jh£gi SHc. Mgto^WT Mpfg^ LOCATION lUTM7 EMMS__________ N 93S171 gAwron 13 - : *it dimension l™?i i50mt> won L5C»iit>_ OoPih »* J*tofla
m
_
SURFACE AROUNQFTT
^mtahpn ccwfW
DESCRIPTION
SAMPLE
Syrnberf
Rmrtcl
D€PTH
imi
sen n*p^
sruefut  •.  *T»ottw«  gn*n  w» plx-yacrt. =£ot Alflt**cra
7yC-rJ
Na
S*zo
ikg I
l<m. ■
Btown rnaat                clay *tft Sfim 'BCtS <MQar<
No
urrpie hM boar
t*«»n
OOtoOX
Top sc*l
:
10 70*3145
Resriual Denw.y#**^                                -srrr aandv *■•* <*•'**■» •^e’Aer
7 V*p* SANOV* SILT                          f«« 'stay t.rrMdua* >p0 ....... w»annq
rerr*r4^ yf bauittc roCM
iJTGWi-r^jtri
’SAMPVNG METHCO           -SHIPPING CONTAINER
B-Thm w*l -vce
O-Tub»
S-p*«i»C !5»Q
O-Shov®
P-Tin
T-MeCP can
H. Car<«j Block
Q'&jb* (ar
U-TYooden doji
R-c^oth bag
2 4]tscarcM
•rspoaci _______________  _ ICWd&y -AfiESL-A. _TEST PIT REPOR T
tUENT Mrtfry aTWnw Ruouraa
’RC.'EC*
^!<yi SIT? UrW
AlTNo
5H££T_ 1 OF___________ 1 Lfrrirurn ^ -  Ara.Pg^g
y
LCCATON iU’Ui E 25031! _N SM-53 c*ev*w“ IffifrtBl
P:T lHME*J5.Csn Lgrrffi lEQwy_________ Wmr. 1Deyi
Surface abound ptt am. dKjrttwn ^.r»3
■CEStrtlPTlC’N
DE*TH SOIL TVP?
Lrris :
itiEij** *Kria*r> grfcn uxi
0HWly. Oder l-WCy Jf>«
iftiM ((*•[««*» =rpn
| SAMPLE
:7yt*'       NO          Stf*
Rrw<
:«m
ifflO
| oouoza
’cpbcH
5-sfMfrt "Ml ■rft c*»y
«fiw -jraasi rod* -ovir^
oryn
Rtsxju*:
wlty day.
FiTTI 02 Mr" Srwnifh r«l.
SLTy CLAY *<fr wry
4f* gifiM . Kt
J
C Kt> - KJ
2
243C
ZQia 12C
r   ■   -'3$
;■ ;.<g
1 . ■ — -«•-■-
1J            -i
'J
R«.dual iC* « rrWV: srowr «ib cut
r
t S .^. 4vms ctcuUk k* ■U-^p* 5ANDV
1       j£LTV t3JUV*L -tfr fo. d>y
¥
iC- ' WUT^nng
ipnhfH Ql UUiK rOC«.
I 40 la 1 FC                        ‘jndpr^fcr1
■S.1MPL V3 ME“HCC       ■S^iPGihQ CONTAINER
fi-Thr* -■*' tLte
t“iDi
G-5***
P-"fl
TJAraor
H.
B*w>
Q-C4ate#
U-WaxSir- dck
--dmF wq
1 Piped cr
UW^bT 2fiffJLA__________
_
Cjte M*r«TEST PIT REPORT
JOB J=MWMtf¥ rYfrHlMfcP^ SMfETT t._ GF________ 1
-• ■■.. ■_<jr
P|^QJC€T
5^
Rfljpifl
LOCATION
iuT^I
E2WM
N        2J^3S_        Ert*
“IT DIMENSION
I ,W *■!
Client Mr^sr .vug tmagti
SURFACE AflOUHO PR ^rt/"-n. ^rsTJCtfl L^r.fffcl
■ AVflh __________ jj
Dfsotjma
samaue
5rntw
Rsnwk
MPTw
SG4L F-TE.
Typ--
No
f«ta:
ilruct-i*
rrcndjf*
C*gen
4kg |                 m i
R ' ' 5-
O'D to QZO
lTdp Adi
8HJ*n.
matt Mrfl
fatf Cl*y <wtr»
VXn»
tttoC* •
■:<jan<
P"?n
Res»aua*    Saif. r«
silfy clay
TOM SILTV
CIA*.
wv«0ierv*9
CfWucr of
■-
r_
[?-. ”
d-
r    *■
r-- ' '
h■■*
fei ■" •' ■'
’5' -'
'
r*-’ - * *
*/
jqjd to i ra
2
2430                 OJOtoi 20 :
■*
r-V.
Residue .
sandy silt
C*^M JWGCW
nn i«i»sri
fire-r
ferii iCC4a
>1 ra
Ltvt-JAf m
u«*:<
SANDv SILT
*rf*i   irw   «¥
n>duJi
refnrart of
tusahc rock
f
'
^*WPUNfi.ygHgQ j7LE*inG.£QNTAiNE.Lr
B-Thn <¥i* lube
G-ohc^
O-Ti.ce
p-rm
S-oasbe. aaj T-M«O C4A
H- Gawd Stock
Q-Oukjx
U-ftWfrn tjcx
9-ctfhMg
2-^i»CJrd«
■timcIdt _____________^__ LO9P« b» A Lem a
Caie MWDgtest pit report
pfTNo pftSTPdi
JOB-FJW6.KV rysABjggr
SHE e~ i _ gf__________ 1
CLIENT Mc^awrer qpOLjCK
PROJECT Am OrfwM if"MWri
LCCAPCN I.L/TKI) E SiK4? N__________________ PIT CIMEN5IQN t waft 1 50
SLRFACE ARQUM3P1T "t*NN: veQglatsjn favffM
SITE CnttnJWJ
939670 clfrvjnoA 13B$m
UPffBari *otn Dxn ^H.^iOf'SKe
W<tth
1 $0 nta C*pTi 2 iQmte
jOESCHIPTtCN
SAME -
Symbol
Remark
DEPTH
304. TYPt
=Go*JUr                t<-X»WWCVJr*w*WV
Type'
■ No
Dea dr
wucfi-rt.
grwi **«■
i’mtS 1
FVlltertV        Mto'        JltfwrcY        Jilin CtfnDM^Xi.an^n
1 kg. i
imt 1
■■MH
Top soil
00 to c 30
C-Jrt prawn mc>^ foe grawtf mi*, jkiy day some gr«* rqoet -arganc
Iflf’QCI
SCfff.   red.   nwtrt   SlLTY   CLAY; product ol bznJfM fn«X
Q KWZ1Q
Residua 1 silty tJ»v
2
2J13D
i d la 1 *q
>3.10
_____
Residua                                cart
1        SAND* SILTY GfiAVE'J w*
sahdy
7 few d*y <fM>du4J W*l
.                  wtrtxmfl                  rtmmaflt           a?
■5j^hW4 fdKMs umSemearh
6-Thn *■*( tub*
G-Sho**i
H- c*ftfrd Bictk
-SHIPPING CQMTAilpEFg
ORUk
? rm
□-GUW jar
R-tWi b^j
S-pLdltc Sag
T-Mttal ^an
U-Wdotfen box
Z-di&cardeG
Irtspawr ___________________________
LaMfsey Atm* A.
Approve" _               _____
Oju Mav gfi
MiTEST PIT REPORT
Client M^ny-orwrar PROJECT Ano Ottdflwa^rwwcn LOCATION (UTMJ. E 2*9745 N _ at dimension i i jo
SITE frurtim*
PIT Na. OHeTE-11
-OS
SHEET _i OF________________ 1
Uwmm tamJhe Ai» FhqHw
339670 El^anon- 13fr5m
Wrftfi_ 1 Kmffl Chwfi s,.-/?ra.
SURFAC E AROUND PIT nrwN Ut v wlaMit goMared.
■DESCRIPTION
DEPT*-*
■ nMs >
Top soil Dfl^ brown ■"nwst fiM grained wft. l*hy ?lty wrtii
wm? yfma -i»tx -ofgarrc
Remark
Nd
Sue                DecrfTi
rkg 1
fffltl
flOlnOM
i^?n
Res*dua |s«t      "»*« s
rDd
ilty cuat;
■ S||fy Eroduct flF bata
fac rock
0 20 Io 2.10
clay
____________________
2  L130
J
>2.10
RCiiduJ Oenikrec *fth .dark ipols
3ANCY SO-TT GRAVEL! wflhi
r*w day |m>dual
weiffienng  en’man[
ram xidmrath
"5AMPUH0 M£ThOC              “SHIPPING CONTAINED
0-TNfi Wjll we*
□-Tub*
5-p**B0c bag
G-5hflMei
P-Tin
T-MWcan
H- C-arvf d Stock
Q-^fau far
U-WMd*ft box
R-Ctoih tag
2 -diMardM
ItWfClor ___________________________ Lagged by Atari A.
AppwH ________ ______
Dwe _May -J{£
ditest pit report
pit Ne OHBTP--0 ■
job
SrfgT 1 QF___________ 1
CUENT         V.rrtgy         tfWjrter         Rc^-uW ^OjECT Ano Dadfn imartan
grrt
0f» rtdwsa wl^oc.
ff
Tom ?frq Dam Ags.RlflrEKf
."CATION            (UTMl.            EM3M 5»lT DIMENSION Ltnath ~ I 50 m*
_
M          _ E’fvafion
_
MVlOtfl SQ-TO
a flQnilS
SUftKACE AflOUND PIT naaffM Hit vfcMatW WWfrtL
‘SAMPLING METHQp               •ShiPdikG CCwTAiNEft
S-TtawJI &bt
OTufce
S-^Mianz frag
5-5harfi
P-Tin
T-Me"j< ran
M- Carted BkKK
iJ-Wa&den aax
S-ikJtii bag
Z-dK«M
inwector __________________________ LGMMby Afcyj A
Acprcnr^ ______________
Dm* Ma> g&
95TEST PIT REPORT
CUEWT.
'ROjECT *q?
irngfep-
SJTc
PrTi*fa QHqrp-g _
SH£ET ■ OF___________* '
v«aaf_jJp»tCT£!-^gLt*
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wnftfi
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MSMIPTCN
SAMPLE
SPirs:o
Renuart
SOIL TfP
Type’
No
------------- .—
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irnti |
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0QW0B5
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D«3iai*5
T
Z
QrgtoOw
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!A
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OftK        WBfl to rRrtci *n 0fB? w«h dirt stria GRAVELLY SAnDV &JLT Mfltn few clay
newuas
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E-O«UC DUQ
T-M4UJ =an
box
R-rtMh taq                   Z-OttcacOed
Approved ..___________
D** MlyJS
Logged by ^1 ATEST PIT REPORT
PIT No DHaHM
JAB- Fwb.ntv tvyWiMMlion SHEFT_ 1 CF____________ i
CLIENT Mtnhtw af Ww Wtwtfai
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.ccation (utme emmm n aam . Efr^uwi jjspm am
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C-Tuba
P-Tifi
Q-OI9S5 .-ar R’dPih bag
S-pijs^ig bag
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Inspector ____ __ ________ Logged gy Ater a a
Approx ______ _______
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PIT NO. OHBTP-6
■rfia _FeM.ib.hfr r-Muaarpn
1
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GHENT Mlrwlrv af Water Rmoufco
PROJECT AioCedeaaa TiCJhon SITE £>*nd
ejsa wtflwe. UMfrfwi from the Dam toft. BigftW
LOCATION (UTM'r E 2406SS Y
9 3 5        _ Elevation. J^Qi’-n 33»_
PIT DIMENSION LawHi 150
Wteih J 50/nta Deplh LMffla
SLPFACE AROUND PIT. fMrtV flat WOfflon CgvwWd.
—
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o a to a .15
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a 15 r<H *J
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Firm 10 SDff. b*o*™»h red :&
■'«J. Jbflhtly rF»C--J4 SILTY CLAY
1
2
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Sait
J
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■SiIMPlIHG WETCO     ■SMIPP’KG CON'  "A1NSR
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R<iMh bag
Z-discardcd
inspector
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■Mfli'Otfcd ____ ___________
Owe M>y iMtest prr report
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r
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1
2
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test pit report
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SHEET J_ OF___________ 1
SITE QhgHflew nllJCt UPlF.ea™ Ehp Axis.R»flni&i
LOCATION |UTM I       E 2*9ATfi._. N 929650 E r/^ion jdfllffl mJ
PIT DIMENSION i wnam t 5fl mrs 
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1 50 tils____Dmjui -L^mEa
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B -Thm wan *lde
O-T ute                              S piastic tk&g
G-Shfl’/fli
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Q ■SHIPPING CONTA
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CLIENT Min-rtrygr Waief. Resource; PROJECT Mo CWMM ifriMBan
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SHEET T . OF1
SITE Oh^idcM vtflfcie Upstream from 1be Pom A*!l
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LOCATION (UTMJ EM8M W                          93^68 El^lran .l.ffii? »l P»r DIMENSION Lefl^b _ IMW Widtti 1_!W mt; _D*pt.1 2,igiTlH SURFACE AROUND PIT wuh fat rtOdKWl covWKL
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DESCRIPTION: stjuctuiw   rrwiftrt. gmm piartcrly
Ih iEncy jr»r
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SAMPLE
Remaa
DEPTH
SOIL
TYPE
T«rt-
NO
Size
>'kq.:
CepSi
mL
symbol
■rntai
D.0 Id D 40
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DW MfltSGTEST PIT REPORT
PIT Mo. C.hBTP-6
JC8 f—mv—WMtQO
SHEET _ 1 OF_________1
CLIENT lilkMlritfWwHwwtl
WfljECT Aita JedfiM ■i-™i,yl " STT1
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'nyj'ht i>-i Va.'ekg-
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SURf^CE jWOUW PiT n—frftiLvwanowd
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, DESORPTION Cotour, c»                                 SAMPLE
DEPTH
I’ltStl 1
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41Appendix C
Laboratory Test Results Summary and InterpretationsJA8LE1 NUMMARY OF ARJQOEDE93A LABORATORY TEST RESULTS
.Pg&JECT: ARJO-LJEDES SA FEASIBILITY STUDY___________________ ____________________
_SUMMAR Y Of LABORATORY TEST RESULTS________________________________ _________
A.CLAY MATERIAL SAMPLES “
1
BORROW
■Mi1 1 tT1 1   J“ IHf f *i ! W xl 3
1
i.specific gravity
ATB
CHfl
DHB
MB
06
L■——
lyPPER LIMIT
2.65
2.72
2.65
2 70
-
2.85
iLOWfFt limit
2.54
2.74
2.58
2.52
-
2.52
average
2.63
2.76
2.70
2.83
2.6fli
NUMBER OF TESTS
14
9
12
9
0
f ..
JI.FREE SWELL
UPPER LIMI 7i
60
-
60
70
60
70
LOWER LIMIT(%i
30
40
40
50
30
AVERAGE i%.
46
47
50
57
46
Inumber of tests
I4
0
a
7
3
1
I
IH. NATURAL MOISTURE CONTENT iNMCl
r
AU Borrow Ar»»
[upper LIMIT f%,-
20
15
25
16
25
LOWER UM1T i%
5
&
12
4
-
4
AVERAGER 1
15
a
1$
12
13
[HUMBER Of TESTS
12
5
4
4
0
[V OPTIMUM MOISTURE CONTENT iOMC,
L'PPER UMIT|%?
‘lower LIMIT, %)
AVERAGES)
[NUMBER OF TESTS
V MAX1MUM 0«Y DBMSrTf <MOOI
All Borrow Arg as
44
24
37 oa
All Borrow Areas
UPpfcRL^TjK^rn  j
J
LOWER LIMITiK^m I
1515
J2U
1346
W24
5 33!
AVERAGE iK^'IP 3>
1429
1 «L4D
1260
ri78
1660
1295
1435
NUMBER O-F FESTS
Vf. PERMEABILITY |K|
SBfiO
1214
1460
All Barrow Arjas
J
IjJPPER LlMlT'Cm/s;
461X10*
I SSX1D '
3.14X10- ‘
6 2X10*
| LOWER L KlTiChi.si
1 64X10 'l
J MXlfl1*
6 2X i r ~
3.14XF0"
62X10*
1 ^-Qlf ill
AVERAGES WSJ
2.85X10
m saxw*
1.14X10 ’
-
0.2X1 O'
'NUMBER OF TESTS
3
1
1
3 24X10 *
1
0
Page rJA6UE 1 NUMMARY OF ARJO-DEDES5ALABQRATORY TEST RESULTS
_PROJECT; ARJC-OED6S5A FEASIBILITY STUDY
a.clay material samples
BOMOW
A>r Borrow Areas
VIE SHEAR STRENGTH
COHESION < C I
ATB
CHB            one
MB
QB
UPf^EQ LIMITi KWm^l
44
37
—
4ft
46
-
46
LOWER L.MlT.KNrti’t
35
34
37
4«
-
34
Ave RAGE iKN/m i
38.8
35.5
38.5
46
-
38.8
’NUM9ER OF TESTS
5
?
2
1
0
All Borrow Ar&a*
angle of internal friction
UPPER LIMIT; ■ I
30
> LOWER LF.Ml
Tf" I
Average
26.7
- ---------- —-------------------
Vlrl EFFECTIVE SHEAR STRENGTH
COHE SION i c I
UPPER      L.MTT      iKN.TrZi
LOWER   UMJT   'KN/rrrl
average ianlw;-
NUMBER OF TESTS
[NUMBER   OF
TESTS
30
19
26.5
5
Aji Borrow A/nai
ANGLE OF INTERNAL TRfCTJON
Ail Borrow Artas
LPPER LIMIT j " I
LOWER LIMIT i " t
NUMBER OF TESTS
Page 2SUMMARY OF AffJQ-DEDESSJ LABORATORY TEST RES LILTS
.PROJECT. AFUO-DEMSSA FEASIBILITY $TUqt
.sjjmhahv of laboratory testresults-
________________________________
'
: A CLAY MATERIAL SAMPLES
______
BORROW
L.OUID limit
All Sorrow Areas
UPPER LlMrT(%I
27
w
71
73
-
73
(lower LIWJT|%>
16
55
55
ei
■
lo|
[AYERAGE|%|
&3
W
64
67
-
63
WM0ER OF TESTS
14
9
12
a
0
1
PLASTIC LIMIT
All Borrow Ar«as
UPPER LIM|7i%)
44
43
St
43
43
51
tOWERLlMlT.'M
34
31
19
33
40
19
AVERAGE.*/
38
36
41
40
41
39
NUMBER OF TESTS
34
9
12
a
0
I.
*W 1TA0LE f !5UMH*fiV CF ARJO-DEOESS* LABOtfUTORY TEST RESULTS
PROJECT : ARJO-DEDE3 5* IRR IGATIOW FEA SIBILTTY STUDY SUMMARY OF LAB OR*TORT TEST RESULTS
B.SAND MATERIAL SAMPLES
SORROW
LOKO5EFERA ]            BORCHE
OVEfi ENTIRE AREA
'■ SPECIFIC GRAVITY
SAND
'LOWER LIMIT-
2.55
2.55
2 55 *
UPPER lIMIT
2.55
Z55
2.55j
lAuERAGf
2.55
2.55
2.55;
NUMBER QF 7EST5
4
2
ILORQANfC content
LOWER LIMIT
D.74
12
0741
UPPER LIMIT -%
2B4
2.12
2.6a
AVERAGE'^'
1,W5
1 66
1.81
NUMBER OF TESTS
4
4
INEFFECTIVE SHEAR STRENGTH
COHESION . C’j
I
LflWERLIMIT (KNfrrY:
3
■-
3
LPPERLlMlT :KN.'Tr'
4
-
4
I1
AVERAGE rKNiWl
3.5
«
f
3.5
TIMBER OF TESTS
3
0
/
INGLE OF INTERNAL FRICTION
I
OWER LHMIT i *
59
-
L
59
IPPER LIMIT i ’ .
62
-
A
VERAGt ■.
62
6033
■
N
UMBER OF TESTS
3
50.33
0
1
Page 1TABLE 1 SUMMARY OF ARJO-DEDESSA LABORATORY TEST RESULTS
PROJECT : ARJ-O-OEDESSA IRRIGATION FEASIBILITY STUDY
SUMMARY OF LABORATORY TE ST R E S ULTS
C.ROCK MATERIAL SAMPLES
RIF
COLISIRI
h RAP
BUKETA
ALL RIPRAP QUARRIES
J-SPECIFIQ GRAVITY
CRQ 1/5
BRQ 1/2
LOWER LIMIT
2.72
2 7®
2.74
•upper LIMIT
2 72
2.76
2.74
AVERAGE
2.72
2.76
2.74
NUMBER OF TESTS
1
1
II. WATER ABSORPTION
~.
I
LOWER UMlt .%)
1.7®
3.24
1.5
UPPER LIMIT %i
1.76
1-24
1.5
AVERAGE %i
1 75
1.24
1.5
NUMBER OF TESTS
1
1
III.POROSITY
LOWER LIMIT i%|
4.24
3 26
3.75
UPPER LIMIT (%>
4 24
32®
3.75
AVERAGER
4.24
3.26
3.75
NUMBER OF TESTS
1
1
IV.ABRASiON
LOWER LIMIT (%)
32
31
31.5
UPPER LIMIT
32
31
315
’’AVERAGE %i
32
31
31.5
NUMBER OF TESTS
1
1
'V. SOUNDNESS
" ------------------------- <
LOWER LIMIT (%i
2 73
241
2.60
UPPER LIMiF(%}
2.78
2.41
2.60
AVERAGER]
2 70
241
2.60
.NUMBER OF TESTS
a
1
■|.tjgLfj           zSUMWAJjr           OF           AftJPd&fpeja*           mBblttTOsVTMT           RESULTS _ggOJECT ,■ ARJQ-DEBf                     IRRIOAHON FEASIBILITY HTflJOT
■ SUMMARY OF LABORATORY Tf ST RESULTS________________________________________
gJIOCK MA TERML SAMPLE?
iz
5HEJ. L QL'ABfliES
p-
.ALL SntLL QUARifflliS
-
AD 1
AD Z
AD 3
AD 4
AD 9
ADS
ADS 2
IlMUWDNESS
c
|LOW£R LIMIT *4,
3 19
4 14
2 16
3 24
a
i Z 26
2 IB
UPPER LIMIT %
3 24
4 14
J1E
3 24
-
2 26
_
4 14
"ZERAGE %
2 M3
4 14
2 16
3 24
-
2 26
-■
<04
HUMflEROF TESTS
I
I
1
1
0
1
M POINT LOAD
DRY
L3W£RL:MJT (KN/nY
»
634
622
STfl
916
m
r2S7
M0
UPPER LIFAT iK.MjiyY
MA
96Z
MM
932
1120
915
1287
1455
AVERAGE
639
BD1
965
>34
600
336
l«7
330
NLiVSER CF TESTS
4
6
5
2
7
1
1
990
LOWER LIMiT .KWjW
>■2
00D
S?0
724 ’
684
7J4
U24
342
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9-ZD
ME
»3B0
see
932
72<
1124
1380
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614
753
795
m
924
1124
780
NUMBER OF TESTS
4
51
S1
2
7
1
1
NLVC3
1
LOWER LIMIT iKftiim1
leeco
ZZ2ZG
23082
210 aS
20420
19 13S"~[
59136
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UPF£R LIMIT |KNAiY
2B4SD
31120
92i$2
3 MSB
29345
24130
92132
aue rage jKNMfflq
23640
255*8
4D974
26:93
25207
2ia7i '
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30375
DUMBER of tests
2
5
4
7
3
2
—L
L
L
P-ag* 1r
V U 4 I
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AUTHOR TITLE
Cali. no.
edition
VOLUME
CAw, NO.

Summery

Arjo-Dedessa Irrigation Project Summary

Arjo-Dedessa Irrigation Project Feasibility Study Summary

Project Overview

The Arjo-Dedessa Irrigation Project is a major water resources development initiative in Ethiopia, comprising:

Main dam on the Didesa River
Saddle dam adjacent to the main dam
Primary canals on both river banks
13,665 hectares of irrigated area

The feasibility study was conducted in 2007 by the Water Works Design & Supervision Enterprise in association with Intercontinental Consultants and Technocrats India Pvt. Ltd.

Topographic Survey

Detailed topographic surveys were conducted for:

Dam site (1:500, 1:1000, and 1:2000 scale maps)
Reservoir area (1:10,000 scale)
Command area (27,000 ha surveyed)
Sample area (500 ha at 1:2000 scale)

72 control points were established with permanent benchmarks. Surveying utilized Total Stations and software including LIS CAD, Land CAD, Surfer, and Civil Designer.

Geomorphological Investigations

The study area features three physiographic regions:

Didesa plain (1270-1400m elevation)
Uplands/ridges (1400-2500m)
Plateau (>2500m)

Key findings about the Didesa River:

Classified as an anastomosing stream type (DA)
Gentle gradient with slope < 2%
Moderately entrenched with well-developed floodplain
Characterized by pool-riffle reaches

Dam construction is expected to significantly alter river hydraulics and sediment transport downstream.

Geological & Geotechnical Investigations

Regional Geology

The project area features:

Metamorphic rocks (Precambrian Alghe Group)
Tertiary volcanic rocks (Jimma Volcanics, Mekonen Basalt)
Quaternary plateau basalts

Dam Site Geology

Stratigraphy at dam site:

Alluvial deposits (3-5m thick)
Colluvial soils
Strongly fractured and weathered vesicular alkaline basalt-rhyolite and trachyte

Key Findings

Right abutment: Massive alkaline basalt with widely spaced joints
Left abutment: Strongly fractured and weathered alkaline basalt
Valley bottom: Alluvial deposits over alkaline-trachy basalt
Saddle dam site: Flood plain deposits over trachyte-rhyolite-alkaline basalt

Seismic Hazard

The site is in a seismically less active area with expected ground accelerations below 100 cm/s² (0.1g).

Construction Materials

Material	Source Locations	Estimated Quantity
Clay for core	Ate, Chewe, Maribo, Dhendessa, Obse	2,082,495 m³
Aggregate	ADCAQ, Maribo	>2,000,000 m³
Shell material	ADQ1, Guche	>9,642,000 m³
Riprap	Buketa, Colisiri	300,000 m³
Sand	Borche, Loko Sefera, Loko Bridge	2,000 m³ (estimated)

Geotechnical Design Considerations

Clay Core Properties

Plasticity Index (PI): 4-68% (avg 24%)
Liquid Limit (LL): >50% (high plasticity)
Swell value: ~50% (potential swelling)
Permeability: ~10⁻⁶ cm/s (low)
Not dispersive (per pinhole tests)

Shell Material Properties

Medium strength class (UCS ~19-18.7 MPa)
Unit weight: 21 KN/m³
Friction angle: 38°

Foundation Treatment

Grouting recommended due to:

Highly fractured rock in some zones
Lugeon values up to 49 in some test sections
Permeability values ranging from 10⁻⁶ to 10⁻⁴ cm/s

Conclusions

The feasibility study provides comprehensive data supporting the technical and economic viability of the Arjo-Dedessa Irrigation Project. Key findings include:

Suitable dam site with available construction materials nearby
Detailed characterization of geological and geotechnical conditions
Identification of potential challenges (fractured rock, clay workability)
Recommendations for foundation treatment and dam design

The project will require additional investigations during detailed design phase, particularly for filter material sources and foundation grouting.