Summary of Baro Multipurpose Project Feasibility Study

THE FEDERAL DEMOCRATIC REPUBLIC OF ETHIOPIA
MINISTRY OF WATER RESOURCES
BARO MULTIPURPOSE PROJECT
FEASIBILITY STUDY
Final Report
Volume 4 A
Geology and Geotechnics Ground Conditions and Ground Engineering
Report Text Annex 4 A
September 2006
NOR plan STI NorconsultTHE FEDERAL DEMOCRATIC REPUBLIC OF ETHIOPIA
MINISTRY OF WATER RESOURCES
BARO MULTIPURPOSE PROJECT FEASIBILITY STUDY
Final Report
Volume 4 A
NORPLAN DU        Norconsult XITHE FEDERAL DEMOCRATIC REPUBLIC OF ETHIOPIA MINISTRY OF WATER RESOURCES
FEASIBILITY STUDY OF THE BARO MULTIPURPOSE
PROJECT
VOLUME 4 A - GEOLOGY AND GEOTECHNICS
GROUND CONDITIONS AND GROUND ENGINEERING
FINAL REPORT
SEPTEMBER 2006
Date of issue
Checked by
Approved by
14 09 2006
Norplan ESS NorconsultFederal Democralic Republic cl Ethiopia - Ministry ol Water Resources Feasibility Study of Bare 1 A 2 Multipurpose Projects
Volume 4 A Papei
Structure of the Feasibility Report
Volume 1
Main Report
Volume 1 is lhe Mam Report a stand-alone volume mat gives me reaser a complete picture of the recommended project and me mam results  s* the study Volume T starts with an Executive Summary
Details and data sheets of studies and analyses with n the various f - ds (ge ology  hydrology, sediments  s«rruiabons  hydrauhe analysts  economy analyses etc.) are given m separate volumes/annexes
Volume 2
Project
Drawing
s of Baro 1 MPP, Bare 2 MPP. and Genji Diversion
Serios
A
General drawings
Senes
Bai
Baro 1 MPP
Series
Ba2
Saro 2 MPP
Series
Ger
Gerji Diversion Pro ect
Volume 3
Supporting Documents Part t - Various analyses Arre* 3 A      Reservoir operation and power production
Annex J 0
Anne* 3 C
Arne* 3 D
Annex 3 F
Annex 3 F
Anna* 3 G
Hydrology and sediment transport Hydraulic    analyses    Octrmisation Access cads
Power system and transmission ires Surveyirq 3rd mapping
□trailed cost estimate
Annex 3 H       Eccnanvc and *injnaal analyses
Anne* J I
Annex J J
Cer i Diverstcn Bae agrcurd studies Fenns, of Reference
Volume 4 A                       Supporting documenta Part 2.
Geology and Geotechnlca.
Ground condition* and ground engineering
Report text and drawings
Annex 4 A Rotary core drillings (ARDCO ROOK3 JV>
Votume 4 B                      Annex 4 8 Core box photographs 
Annex 4 C Field permeability tests 
Annex 4 D Teat pit logs
Volume 4 C Annex 4 E Laboratory test results (ARDCO ROOtO JV>
VcihlHH? *
Annox 4 F Report from geological mapping by Mengesha and Molta Annex 4 G Seismic Hazard .Assessment at Ram Dani Site (Geophysical Observatory Science Faci^ty Addis Ababa University) rnvinmiimnui Impact Ass»s,m«ri
^vwvn*** >*** '«
1- •'<»* ■*- NORPLAN - NORCONSULT - LAHMEYER JV
In association wtih ShetMlle Engmeenrg anti WWDSE1
IFederal Democratic Republic ol Ethiopia - Ministry of Water Resources Feasibility Study of Bare 1 4 2 Multipurpose Projects
Volume 4 A Page li
TABLE OF CONTENTS - VOLUME 4 A
TABLE OF CONTENTS - VOLUME 4 A...........................
LIST OF TABLES
LIST OF FIGURES................. .............. -................ -.......... ....... *.................. ............ *...... *...... —*.........................
LIST OF ANNEXES........ . .................. -.................................................................. ............ . ................. ................. 1
LIST OF DRAWINGS ....................................................... ............................. ................ ....... *........................ ..... •’
1       SUMMARY.................... .............. ..... .................
IV
2        INTRODUCTION................. ...........................................-..........-................ *....................... *.....................2-1
3        BACKGROUND AND GENERAL LAYOUT
....... ........................ ............................. .......... 3-1
3 1 Overview of proposed hydropower development on Bare River
..... 3-1
3.2    Bare 1 - Bnef description of the recommended project             —            ...... ................... 3-2
3.3    Baro 2 • Brief description of the recommended project
...... .................. .     ........ ..     3-2
3 4 Genji Diversion - Brief description of the recommended project...............          ........................... 3-2
4        EXISTING INFORMATION.................................. .........—...... ............................................. ... .............. 4-1
4 1 Maps, aerial photographs and satelliie image
.... ....
4-1
4 2 Previous reports ......................... ...................................... .................. .................................. ...... 4-1
5
REGIONAL GEOLOGY - A SUMMARY....................................... ..... .................................
...........
............5-1
6
6.1 62
GEOTECHNICAL INVESTIGATIONS - STRATEGY, METHODOLOGY AND
PROGRAM.......................... . ...... ........................................................ ................................
...........
............ G-i
Strategy ' procedure for geological mapping and site investigations
5-1
Site investigation program... ............
6-1
62 1 Geological mapping .................... ...........................
622     Seismic Refraction Profiling .................
623     Excavation of lest pits _____
62
6 2 4 Rotary core drilling .......................................
...6-2
...6 3
63
6.4
Laboratory testing .
5 3 1 Laboratory testing of soil samples
6,3.2 Laboratory testing ol rock samples ________
Definitions - rock weathering ....
6-3
.6-3
.6-4
.6-5
7
results of the investigations
7.1
7.2
General.................................... ........
Exploratory core drillings.
7 2 1 General ......................... . .
7-1
........ 7-1
7 2 2 Infor ma ton on soil overburden, weathering and degree of fraclurinq
........... 7-1
72 3 Baro 1 boreholes........................
I
.... ... .7-7
7 2 4 Baro 2 and Genji boreholes
...... 7-14
..... 7-15
73
Permeability conditions.....................
.....7-17
BM0   Q
V lurm4A Gadw-1  September 20iw.doc NORPLAN - NORCONSULT
4
- LAH
MEYER JV
in association with Shebelle Engineering and VW/DSEFederal Democratic Republic of Ethiopia - Ministry of Water Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
7 4 Ground waler
7 5 Test Pits .............................................
7 6 Laboratory Results
7.61 Rock strength - UCS
7 6.2 Petrographic analyses
7 6 3 Sol Samples Testing.................
7 6 4 Construction materials testing
8 PROJECT GEOLOGY - BASED ON GEOLOGICAL MAPPING AND SITE
Volume 4 A Page m
7-25
7-26
7-27
. 7-27
7 30
7 30
7-35
INVESTIGATIONS.........................................................................................................................8-1
8.1 General geology.................................................................................................................................... 8-1
8              t 1 Geology of the Baro 1 area
8-1
8              12 Geology of the Baro 2 I Genji area   ................................................................................. 8-5
9       ROCK ENGINEERING PREDICTION     - GENERAL.................................................................. 9-1
9 1 General consideration regarding excavation methodology ...................................................................... 9-1
9  2   Tunnelling properties 
9 3 Rock stress conditions and influence on tunnels ...
9 4 Stability conditions I design considerations ................... ....
9-1
................................. 9-2
9-3
9 5 Rock failure modes needs for rock support I rock strengthening ............................. 9 3
9.6 Rock mass classification ................................... . .............. ................. ...
............ 9-6
9 7 Rock support philosophy 
9 8 Tentative prediction of rock support needs 
............................ ............................................... 9-7
98
9 9 Transition between unlined headrace tunnel and steel lined penstocks, location
of concrete plug-design considerations ........................ .... 9 10 Groundwater control in underground openings 
.... ............................. 9-11
...... ............................................ 9-12
10      GROUND ENGINEERING PREDICTION - BARO 1..................................... „......................... 10-1
10            1 Dam
................... ...
10 1
10.1         1 General          ............................................................................................ 10-1
10            1 2 Dam options   ...
...... . . 10-1
10            1.3 Desgn parameters tor embankment dam design              ..................... ..................... 10 3
10.1         4 Available materials.        ............. ........ .
....... . ..... ................. 10-3
10            1 5 Foundation treatment & excavation.... ...................... .............................. 10-4
10.1.6 Dam options considerations ............................................ ...... .......................... .................... 10-5
10            1 7 Conclusion - Recommended dam type       ...... ....... ..................... ...... .................... 10-7
102 Subsurface constructions ............................................ .............. ................................... ................... 10-8
10 2.1 Headrace tunnel and shafi
10 2.2 Power station complex         ........... ..... 10 2 3 Tailrace tunnel
...       ...... 10 9
...
............. 10-12
10-11
.
10 2 4 Access tunnel and cable tunnel .. ............ ........ .. ............................... .................. 10 12
11     GROUND ENGINEERING PREDICTION - BARO 2 AND GENJI........................................ . 11-1
11  1 Baro 2 and Genji dams ............... ... ........................................... ............. ...
.11-1
112 Subsurface constructions ........................................ ...
11            21 Baro 2 Headrace system ...         ...
11            2 2 Genji Headrace system              ..... 11-7
............................................................... 11-4
...... ....................................... .115
11            2 3 Power station complex ....................................... ................................... _................. 11 7
11            2 4 Access tunnel and cable tunnel. ... 12     SEISMIC HAZARDS
..
11-8
B»ro volume - Geology - M SeriemOe. 7006
NORPLAN - NORCONSULT - LAHMEYER JV in association w>th Shebelle Engineering and WWDSErll           Federal Democratic Republic of Eth*op'a - Ministry of Waler Resources Feasibility Study of Barn 1 & 2 Multipurpose Projects
Volume 4 A f’age w
LIST OF TABLES
Table 6-1: Core drilling, number and lengtn of bore holes................ ......... 6-3
Table 7-1' Rotary core drillings - Baro i
Table 7-2 Rotary core drillings - Baro 2 and Genji................. .................. ...... ....................... ^-7
7"^
Table 7-3 Baro 1 dam area - summary of information from exploratory boreholes ........................... .+ 7-8
Table 7-4 Barn 1 tunnel area - summary of information from exploratory boreholes Table 7-5 Baro 2 and Genji dam areas - summary of information from exploratory 
7 -9
boreholes 
...... ................................. -...................... ................................ 7’10
Table 7-6: Bare 2 and Genji tunnel areas - summary of information from exploratory 
boreholes.
............. •........................ .......... . ...................-........ -............... 7'11
Table 7-7: Summary of field          permeability test results for Baro 1   Dam Area ........................... 7-19
Table 7-8 Summary of  field          permeability test results for Baro 1   Tunnel Area
Table 7 9 Summary ol  field          permeability test results for Baro 2   Dam Area
Table 7-10. Summay of field permeability test results for Baro 2 Tunnel Area ...
Table  7-11.  Summary  of  field  permeability  test  results  for  Baro  2  Tunnel  Area
(Continued} ....................................... ........ ..... ..................... .........     .      ...... Table 7-12 Summary of field permeability test results for Genji Dam and Tunnel Dam
7-20
7-21
.. 7-22
7-23
Areas ................................................ .......... ......................... ........ ................................. 7-24
Table 7-13 Baro 1 exploratory boreholes. Depths to the water table. ... Table 7-14 Baro 2 exploratory boreholes Depths to ground water table.... Table 7-15 Baro 1 dam site-UCS testing of core samples 
Table 7-16 Baro 1 tunnels - UCS testing of core samples 
Table 7-17 Baro 2 and dam sites - UCS testing of core samples............ Table 7-10. Baro 2 and Genji tunnels — UCS testing of core samples ....
. ..
..... .
..... 7-28
.... 7-26
7-26
.... 7-28
...       ___ . ..7-29
Table 7-19 Baro 1 Petrographic thin-section analyses, conducted at the Mineralogy & Petrography Laboratory of Ethiopian Geological Survey .
Table 7-20 Baro 2 Petrographic thrn-section analyses, conducted at the Mineralogy &
7-29
7-31
Petrography Laboratory of Ethiopian Geological Survey.................................................. 7-32
Table 7-21 Summary of classification and compaction tests Baro 1       .......... ............................... 7-33
Table 7-22 Summary of classification and compaction tests Baro 2 .................................................7 34
Table 9-1: Rock quality classes, rock support needs in tunnels (D) and shafts (O)
........... 9-9
Table 9-2 Baro 1 Tunnels, tentative classification of rock mass quality   .....................................9-10
Table 9-3 Baro 2 and Genji Tunnels, tentative classification of rock mass quality.
Table 10-1 Excavation and grouting depths-dependent on dam type...................... 10-4
... 9-10
Table 10-2 Example 1 & 2 Excavation and grouting depths - dependent on dam lype ................... 10 5
Table 10-3. Assessment of alternative dam types......
Table 10-4 Baro 1 underground constructions dimensions ................... ............................ 10-9
10^
Table 11-1 Baro 2 underground constructions dimensions ........................................................... , n_4
Table 11 2 Genp underground constructions, dimensions .......................... ....... ■................... i V5
Table 12-1 Peak Ground and Spectral Acceleration at 5% damping ...
....
12-1
Biro volume 4A - Gwtofly - 14 Sepiember 2006 doc           NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSEFederal Democrat*: Republic of Ethiopia - Ministry of Water Resources
Feasibility Study of Bam 1 & 2 Multipurpose Projects
LIST OF FIGURES
Figure 3-1: Barol. Baro 2 and Genji diversion schemes Project location
Figure 5-1. Geological map Gore scale 1 250.000. Mengesha Teferra et al. Ethiopian Institute of Geological Surveys. 1907 Location of dam sites shown
Figure 7-1 location of rotary core drillings for Baro 1 dam and tunnel .
Figure  7-2  Location  of  Rotary  core  drillings,  test  pits  (New  *N")  and  old  TP  from PrefeasitMlrty study at Baro 1 dam site
Figure 7-3 Locations of rotary core drillings al Baro 2 and Genji project area
Figure 7-4 Locations of rotary core dnllings and new lest pits at Baro 2 dam site
Figure 7-5 Distnbution of RQD values in boreholes B1D-1 to B1D-7, with reference to classification by International Society of Rock Mechanics (ISRM)
Figure 7-6 Distnbution of RQD values  in boreholes  B1T-1 to BlT-6 with reference to
Volume 4 A Page v
3-1
5-2
7-2
7-3
7-4
7-5
7-12
classification by International Society of Rock Mechanics (ISRM) ................ ..........................7-12
Figure 7-7: Distribution of RQD values in boreholes B2D-1 to B2D-4 GJD-1and GJD-
3. with reference to classification by International Society of Rock 
Mechanics (ISRM) II should be noted that only the gneiss section below
depth 28m is included in B2D-1................................................................................................. 7-13
Figure 7-8 Distnbution of RQD values in boreholes B2T-1 to B2T-6 and GJT-1. with
reference Io classification by International Society of Rock Mechanics 
(ISRM) ........................................................................................ ......................................... 7-13
Figure 7-9 Distnbution of UCS figures from core samples in Baro 1 and Baro 2 ................. 7-30
Figure 8-1 Foliation • Baro 1 Equal-area stereonet (Schmidt net), lower hemisphere Figure 8-2 Joint orientations - Baro 1. Equal-area stereonet (Schmidt net), lower
hemisphere Contours show showing concentrations of poles to joint
planes ............................ . ......................... .................................... .......................... 8-3
Figure  8-3  Joint  orientations  -  Baro  1  Rose  diagram  statistical  distribution  of  joint strike orientations 
Figure   8-4   Foliation   Baro   2   and   Genji   Equal-area   stereoret   (Schmidt   net),   lower
hemisphere.......................................................... .............................. ................. 8-7
Figure  8-5  Joint  orientations  -  Baro  2  /  Genji  Equaf-area  stereonet  (Schmidt  net), lower hemisphere Contours show concentrations of poles to joint planes 
Figure  8-6  Joint  orientations  Baro  2  /  Genji  Rose  diagram,  statistical  distribution  of
8-2
8-4
8-8
joint stnke orientations......... Figure 9-1 Applications of rock bolting
.................. ......................................................... 8 8
........... 9-3
Figure 9-2 Application of sprayed concrete ....................... ......................................................................... 9-4
Figure 9-3 Typical design of sprayed concrete nbs Figure 9-4 Cast-in-place concrete lining
................. 9-5
.................................... ...............................................9-5
Figure 9-5 Application of spiling bolts ..................................... ................. ......................... ....................... 9-6
Figure 10-1 Geological profile in Baro 1 Dam axis 
.......... ....................................... 10-2
Figure   10   2   Baro   1   Rose   diagram   with   statistical   distribution   of   joint   strike
orientations ........... .......................................... ...................................... ............................ 10-10
Figure 11-1 Geological profile in Baro 2 dam axis, showing quite different foundation
condition on the left bank and right bank ...
..... 11_2
Figure 11-2 Geological profile in Genji dam axis showing favourable foundation
conditions for a massive concrete dam
......... 11-3
Baro Volume JA Geotogy - 14 September 2006 doc                    NORPLAN - NORCONSULT - LAHMEYER JV
m association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Waler Resources Feasibility Study of Bara 1 & 2 Multipurpose Projects
Figure 11-3: Baro 2. Rose diagram wilh statistical distribution of joint strike
Volume 4 A Page w
11-6
orientations 
• .......................................................................
LIST OF ANNEXES
Annex 4 A: Rotary core drillings (ARDCO- RODIO JV)
Annex 4 B Core box photographs
Annex 4 C Field permeability tests
Annex 4 0 Test pit logs
Annex 4 E Laboratory test results (ARDCO- RODIO JV)
Annex 4 F Report from geological mapping by Mengesha and Molta Annex 4 G: Seismic Hazard Assessment at Baro Dam Site (Geophysical Observatory 
Science Faculty, Addis Ababa Umversrly)
LIST OF DRAWINGS
Drawing Bal-EOf
Bare 1 “ Project Area - Geological Map
Drawing 0a1-EO2                     Baro 1 - Dam Area - Geological Map Drawing Bat -E03                     Baro 1 - Geological Section along Dam Axis Drawing Ba1-ECM                    Baro 1 - Geological Section along Waterway
Drawing Ba2-E01 Baro 2 / Genji Project Area - Geological Map
Drawing Ba2-E02
Bara 2 - Dam Area - Geological map
Drawing Ba2-E03
Baro 2 - Geological Section along Dam Axis
Drawing 8a2-E04
Baro 2 - Geological Section along Waterway
Drawing Gen E01
Genji - Geological Section along Dam Axis
Drawing Gen E02
Genji - Geological Section along Waterway
Baro volume4A Gtotogy M September 2006 due NORPLAN - NORCONSULT -LAHMEYER JV
in association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Water Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
LIST OF ABBREVIATIONS AND ACRONYMS
Volume 4 A Page vii
A
Unit of elecinc current (Ampere)
A
Area (of tunnels)
AC
Alternating Current
ADH
Aswan High Dam
ARF
Area Reduction Factor
AVR
Automatic Voltage Control
B/C ratio
Benefit/Cosl ratio
•c
Degree Celsius (centigrade)
CCGT
Combined Cycle Gas Turbine
CFRD
Concrete Faced Rockfill Dam
cm
centimetre
CN
Curve Number
lev
Curve of Vanation
D
Diameter
DC
Direct Current
DS
Downstream
DSM
Demand Side Management
DTM
Digital Terrain Model
EIA
Environmental Impact Assessment
EIRR
Economic Internal Rate of Return
EELPA
Ethiopian Elednc Light and Power Authority
EEPCo
Ethiopian Electric Power Corporation
EFY
Ethiopian Fiscal (or Financial) Year
EMA
Ethiopian Mapping Authority
ENCOM
Eastern Nile Council of Ministers
ENSAP
Eastern Nile Subsidiary Action Programme
ES
Essential Switchgear Section
ETB
Ethiopian Bm (national currency unit)
ETC
Ethiopian Telecommunicabons Corporation
EV1
Extreme Value Type 1
FIRR
F inanoal Internal Rale of Return
I 7*7”
Ful Supply Level
FWL
Flood Water Level
GPS
Global Positioning System
GWh
1000 MWh (Gigawatt-hour)
ha
Hectare (unit of area)
HD
Hydrology Department
I HEC1
Hydrology simulation model HEC1
HH
Household
HMI
Human Machine Interface
HPP
Hydro Power Project
HV
High Voltage
HVAC
High Voltage Alternating Current
HVDC
Voltage Direct Cunent
Hz
Unit of frequency (Hertz)
Baro Volume 4A Geology 14 September 2006 doc NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSE•
Federal Democratic Republic of Ethiopa - Ministry of Water Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Page vtii
List of Abbreviations, continued
ICB
International Competitive Bidding
ICOLD
International Committee on Large Dams
ICS
Interconnected System
IDC
Interest Dunng Construction
IDEN
Integrated Development of the Eastern Nile
IEA
Inflial Environmental Assessment
IP0
Isolated Phase Bus
(SRM
International Sooety for Rock Mechanics
ITCZ
Inter Tropical Convergence Zone
ik
coefficient of permeability
km
kilometre
kV
1000 volts (kilovolt)
kVA
1000 VA (kilovolt ampere)
kWh
1000 Wh (kilowatt-hour)
kW
1000 Watt (kilowatt)
LAN
Local Area Network
LCGEP
Least Cost Generation Expansion Plan
LCU
Local Control Unit
■■■
LF
—       —
Ratio of average load to peak load (Load factor)
LLF
Ratio of peak loss Io average loss (Loss load factor)
LFO
Light Fuel Oil
LRMC
Long-Run Marginal Cost
LS
Lump sum
LV
Low Voltage
LWRL
Lowest Regulated Water Level
metre
MDE
Maximum Design Earthquake
mm
millimetre
nrVs
metres per second
m3/s
cubic metres per second (unit of flow)
MAF
Mean Annual Flood
MAP
Mean Annual Precipitation
masl
metres above sea level
MCC
Motor Control Centres
MOI
Minimum Operating Level
MoWR
Ministry of Water Resources (Ethiopia)
MSHP
Medium Scale Hydropower Plants Study
MPa
10 Pa (Mega-Pascal, unit ol pressure (stress))
MPP
Multipurpose protect
MUSD
Million United States Dollars
MVA
1000 kVA i,Megavolt-ampere)
MVAr
Megavolt Ampere reactive rating
MV
Medium Voltage
MW
1000 kW (Megawatt)
MWh
1000 kWh (Megawatt hour)
N
Newton 4 = 1 kg x acceleration of gravity) (unit of force)
Bjro Volume - G»o'<W -14 September ?Me Ooc NORPLAN - NORCONSULT - LAHMEYER JV in association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Water Resources Feasibility Study ol Baro 1 & 2 Multipurpose Protects
Volume 4 A Page ix
List of Abbreviations, continued
f1 NA
I NELSAP | NBI NMSA NPV O&M
' Not Applicable
Nile Equatorial Lakes Subsidiary Action Programme Nile Basin Initiative
National Meteorological Services Agency Net Present Value
Operation and Maintenance
OPGW              | Optical Fibre Ground Wire
Pascal (- 1 N/m*) (unit of pressure)
Ratio of active power on apparent power (Power factor* Probable Maximum Flood
Probable Maximum Precipitation Power I me Carrier
Power Purchase Agreement Power System Stabiliser
Per unit
Present Value Resistance (electnc)
Roller Compacted Concrete Request lor Proposal Regional Hydrological Office
ROW ipm rm 5 RQD s (sec) SC
Right Of Way 
revolutions per minute
root mean square
Rock Quality Designation
second
Senes Compensation (transmission)
Barn volume 4A - Geology 14 September 2006doc NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engmeenng and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Waler Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Page x
List of Abbreviations, continued
USD
United States Dollar
usscs
United States So«l Conservation Service
UTM
Universal 1 ransverse Mercator grid (maps)
V
Unit of voltage (Volt)
VA
Unit of apoarent power (Volt ampere)
VAr
Unit of reactive power (Volt-ampere reactive)
W
Unit of active power (Watt)
Wh
Unit of energy (Waft hour)
WMQ
World Meteorological Organisation
pWTP
Willingness to pay
BaroV0*ume4A Geology-14 September 7006 dec NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Water Resources Feasibility Study of Bare 1 & 2 Multipurpose Projects
Volume 4 A Page 1-1
1
SUMMARY
Site investigations The idea behind the conducted site investigation program has  been to address  important geotechnical issues  necessary  to demonstrate, to Feasibility  level, the technical and economic  feasibility  of developing the scheme with sufficient level of investigations  This  program included geological mapping, test pits, exploratory  core drilling and in-situ perme ability  testing in the boreholes  Al Baro 1, 13 holes  with a lolal length 940 m were drilled at Baro 2 and Genp, with a total length of 1106 m Planned seismic  refraction profiling at dam sites  has  not been earned out due to logrsiical and weather problems  The missing profiles  are not of decisive importance for the conclusions  for this  report, but it is  rec ommended to be carried out the seismic  profiling in the final design stage to more precisely  decide on alignment and depth of foundation of the dams
Laboratory testing Laboratory  testing of rock, mainly  uniaxial compressive strength testing, has  been conducted for a number of core samples  Petrographic  com position of rock  samples  has  been assessed by  thin-section analyses  in microscope Laboratory  testing of soil samples  for determination of engi neering properties  have composed classification tests, compaction tests and shear strength tests
Properties   assessed   by   these   investigations   have   been   analysed   and classified according to internationally used classifications systems.
Type of rock
Both project areas  are located wilhin precambrian crystalline basement rocks  belonging to the Alghe Group (ARI). These gneissic  rocks  are overlain by basaltic lava flows belonging to the Mekonen Basalts
Soil formations A significant part of the bed rocks is blanketed by red lateritic soil, mostly residual, but also same colluvial Along the banks  of Baro River and its tributaries, alluvial materials  are found as  scattered deposits  of small quantities
The Baro 1 area is  in general soil covered, but with partly  exposed rock at riverbanks  and in riverbed and in areas  with steep terrain. Soil thick ness in the dam area boreholes varies from about 4m in B1D-1 io about 51m in B1D-5 In the tunnel area, the soil thickness  varies  from about 2m in B1T-5 to about 20m in B1T-6
The Baro 2 area is likewise in general soil covered with exposed rock at nverbanks and in riverbed Soil thickness in the dam area at right bank is thin, varying within the range of 0 to 6 m overlying slightly  weathered to fresh gneiss  At left embankment, the soil cover is  13 - 16 m in the two boreholes  drilled in the dam axis. Along the tunnel alignments, thickness of residual soil varies, up to approximately 40 m as determined at 82T-3
The soil cover at Genp dam site is modest, between 0 and 6 m within the dam foundation. Rock  is  exposed in riverbed Along the tunnel, soil cover vanes  from none at the crossing of Baro River branches  up con siderable thickness where the tunnel joins the Baro 2 tunnel system
egf0 Volume4A ociogy m September 2ow doc NORPLAN - NORCONSULT - LAHMEYER JV
in association with Sbebelle Engineering and VVWDSEfederal Democratic Republic of Ethiopia - Ministry of Water Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Page 1-2
Weathered zone Depth of weathering at Baro 1 and Baro 2 project areas is variable In the exploratory bore holes at Baro 1 dam srte, thickness of pronounced weathering (highly  or severely  weathered material), below what has been defined as soil varies from 0 m to 6 m In the boreholes along the tunnel alignment the thickness vanes from 0 m to 8 m
In the boreholes at the Baro 2 dam, weathering thickness varies from 0 m on the right side of the river to 21 m in the upper borehole. 02D-1. on the left side of the river Some sections  of basalt in the upper part of B2D-1 are slightly to moderately weathered but the general rock quality is though poor down to the top of the gneiss at depth 28 m
Jointing of rock mass From geological mapping at Baro 1. most dominant joint strike direction
is found to be about NNW - SSE Degree of fracturing or jointing of the rock mass is concluded by use of RQD values assessed from the core samples  The rock  quality  in regard to RQD-values  is  highest for dam area boreholes B1D-1, -2. -6 and -7 . with more than 60% of the holes below the weathered zone classified as High or Very High In borehole B1D-4 and -5 is  found the lowest quality, with about 0% classified as High or Very High
Of the Baro 1 tunnel area boreholes. B1T-2. -3 -4 and -6 have more than 80% classified as  High or Very  High Poorest quality  is  found in B1T-1. with 54% classified as High or Very High.
In Baro 2 / Genji project area the dominant joint onentation is with strike about E-W Another orientation is  with stnke about N-S. parallel to the strike of foliation The rock quality, defined by RQD-values is in general high at the dam sites, with more than 90% below the weathered zone classified as  High or Very  High in holes  B2D-3 and B2D-4 and both holes at Genji dam site Exceptions are B2D-1. with 75% of the gneiss in this category, and B2D-2, with 69%
Of the Baro 2 tunnel area boreholes. B2T-4 and -5 and GJT-1 have more than 80% classified as High or Very High Poorest quality is found in B2T-1, with 48% classified as High or Very High.
Tectonic faults
Tectonic faults or weakness zones are nol visually observed in the Baro 1 and Baro 2 area, due to soil cover Topographical lineaments identified by stereographical interpretation of aerial photographs are though in many cases concluded related to faults or weakness zones
Rock strength Of totally 36 samples from Baro 1 boreholes. 44% showed High Uniaxial compressive strengths (UCS) and 56% Medium strength Of 38 samples at Baro 2. 8% are classified as Low, 34% as Medium and 58% as High
Ground water                 In the boreholes at Baro 1 dam site depths to the deepest water table
vary between about 5 m in B1D-1 and B1D-4 and about 22 m in B1D-2
In boreholes in Baro 1 tunnel area, depths vary between about 5 m and about 28 m
At the Baro 2 dam site, depths to deepest water table vary from about 8 m in B2D-3 to close to 23 m in B2D-1 These reported depths  corre spond to water levels about 1315 masl in B2D-1, 1304 masl in B2D-2. 1299 6 masl in B2D-3 and 1205 masl in B2D-4
H ~volume 4A Geo'ogy 14 September ?oo6 boc NORPLAN - NORCONSULT - LAHMEYER JV
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_Federal Democratic Republic o1 Elhiopia - Ministry of Water Resources Feasibility Study of Baro I 4 2 Multipurpose Projects
Volume 4 A Page 1-3
Dam foundation The topography  of the Baro 1 dam site is  characterised by  a narrow V- shaped gorge to the left side of the river, and a much wider valley al the present course of lhe nver A ridge rising up to dam crest level separates the gorge and the present river valley  The soil cover overlying compe tent rock on both sides and in the middle of the left narrow gorge is shal low whereas  the soil-cover on both sides  of the riverbed in the main val ley  is  partly  deep up to 50 m at the upper part of the right dam abut ment The combination of topography  and ground conditions  is  favour able for dividing the dam in two different sections:
•   A   concrete   spillway   dam   structure   located   in   the   narrow   gorge founded on competent bedrock
■  A  main  concrete  faced  rock-fill  dam  (CFRD)  is  foreseen  across  the mam  river  valley  Because  of  the  large  depth  to  bedrock  at  the  upper end  of  right  abutment  the  rock  fill  dam  as  well  as  the  concrete  face will  be  founded  in  firm  residual  soil  In  lhe  riverbed  as  well  as  the  left abutment,  the  concrete  face  will  be  founded  on  rock,  whereas  the rock fill body will partly be resting on firm residual soil
Saddle  dams  of  modest  heights  at  two  depressions  to  the  right  of  the mam dam will be constructed as clay core embankment dams
The topography  and ground conditions  on Baro 2 dam site as  well as  the size of lhe dam differ considerably  from Baro 1 dam At the right side of the nver. the terrain rises  gently  away  from the river Good competent granitic  gneiss  rock  is  found at shallow depth all the way  up to dam crest level Bedrock  is  exposed in lhe riverbed The dam is  designed with a concrete spillway- and intake structure located at right riverbank  On both sides  of this  concrete structure clay  core rock  fill dams  have been proposed
At the left nver bank  the ground surface rises  steeply  from the riverbed The ridge comprises  of residual soil and basalt boulders  overlaying ba salt rock  Underneath lhe basalt, a severely  weathered or decomposed gneiss  rock  of high permeability  has  been identified as  transition to sound gneiss  rock. This  high permeability  layer requires  special precau tions  to prevent unacceptable high seepage gradients  through the ground An impervious* clay  blanket along the upstream side of the ridge has  been proposed for lhe feasibility  design However, various  so lutions  such as  deep slurry  trench walls  or jet grouting through the basalt into (he weathered zone may  prove more favourable Such solution should be considered based on more detailed investigation of the transi tion zone in the final design phase
The Genji dam site is  located in a relatively  narrow V-shaped valley, which calls  for a spillway  structure within a concrete dam The ground conditions  are favourable for a massive concrete dam as  rock  is  ex posed in the riverbed and the soil cover in both abutments  is  shallow in the magnitude of 0-5 m
Tunnelling conditions Both al Baro 1 and Baro 2 the tunnels are entirely located within the Pre
Cambrian basement rocks  These rocks  are concluded suitable for tun nel construction and of sufficient quality  and strength for being self- supporting in tunnels and other underground openings Weakness
Baro volume 4A            W 1* September 2006 ooC
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“
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federal Democratic Republic of Ethiopia - Ministry of Water Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A
Page 1-4
zones are expected to affect the rock stability and rock support needs Satisfactory stability conditions are expected obtained in general by use of rock support measures such as rock bolting in combination with steel fibre reinforced sprayed concrete, and with heavier structural support e g steel reinforced sprayed concrete arches or cast concrete lining, in case of weakness zones of poor quality Leakage zones encountered by tunnels may need to be sealed and use of cement grouting is considered generally as sufficient
Bare volume 4A - Geology 14 September 2006 doc NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia Ministry of Water Resources Feasibility Study of Baro t & 2 Multipurpose Projects
Volume 4 A Page 2-1
2
INTRODUCTION
The present Volume 4 of the Feasibility  Study  Report describes  the geo technical site investigations  the ground conditions  and ground engineer ing considerations  for the Baro Multipurpose project Results  of site in vestigations, including exploratory  drillings  and field permeability  tests  as well as  laboratory  test results  are presented Geological data and ground parameters  are interpreted in view of planned constructions, used as  in put for design considerations  and cost estimates  Ground engineering and construction works are also discussed
Details  and  data  from  the  geotechnical  site  investigations  are  presented in Annex 4 A through Annex 4 F.
This report. Volume 4, consists of
•      Volume 4 A. containing the report text, geological drawings and An nex 4 A (bore hole logs).
•      Volume  4  B  containing  Annex  4  B:  Core  box  photographs.  Annex  4 C Field permeability tests, and Annex 4 D Test pit logs
•     Volume 4 C. containing Annex 4 E. Laboratory test results (ARDCO- RODIO JV). Annex 4 F Report from geological mapping by Mengesha and Molla. as well as Annex 4 G Seismic Hazard Assessment at Baro Dam Site (Geophysical Observatory Science Faculty, Addis Ababa University)
Bare Volume** Geology -1 * September 2005.Hoc                          NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia — Ministry of Water Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Page 3 1
3                          BACKGROUND AND GENERAL LAYOUT
Overview of proposed hydropower development on Baro River
General drawings A01. A02 and A03
A Prefeasibility study of the Genale. Guder, Baro and Geba Hydropower Projects  was  conducted by  NORPLAN AS I Norconsult AS group of Consulting Engineers in 1999
The projects  being considered in the present feasibility  study, are lo cated along the Baro River in the Baro-Akobo Basin between Gore and Bonga. approximately  600 km west of Addis  Ababa see Figure 3-1 They exploit the hydropower potential of a 55 km long stretch of the up per reaches of Baro River with a total gross head of some 700 m be tween the elevations 1520 masl and 810 masl
The Baro 1 and Baro 2 schemes form a hydropower cascade the tail water of the upper scheme (Baro 1) will be the headwater for the lower plant (Baro 2)
Genp River is a tributary to Baro River, with confluence some 3 km downstream of the Baro 2 dam site A previous study [3] has shown that assuming that there is a market for the largely non-firm energy, it is at tractive to integrate the flow of Genji into the Baro 2 scheme Due to its lower intake level, the Genji diversion needs a separate headrace wa terway to the Baro 1 powerhouse
BAmitrr
GfcNJl DIVERSION
llt&dnuz
Wcit A Power I nuke
Intake l>*id
1
Headrace
Sp i way and Power Intake
Main dam
Saddle dam
RcMTvnit
_
Bar
Figure 3-1 Barol, Baro 2 and Genji diversion schemes Project location
2006^          _NORPLAN^NORCONSUlF- LAHMEYER"JV in association with Shebeile Engineering and WWDSE/©K Federal Democratic Republic of Ethiopia - Ministry of Waler Resources JjgP Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Page 3-2
3.2
3.3
3.4
Baro 1 • Brief description of the recommended project
Project location drawing Ba1-B0l
Baro 1 is  the upstream one of the two hydropower schemes  on Baro River The dam of Baro 1 creates the head pond for the cascade With a live reservoir volume of 993 million m3 some 74% regulation is obtained The selected dam site is  favourable in the respect that it is  located di rectly  upstream of a steep river reach with rapids  where the nver drops 130 m over a short distance The site offers the most narrow valley pro file in the area and thus  minimises  the required dam volume Upstream of the dam site the valley widens and thus provides a reservoir with fa vourable elevation-capacity  relationship Waterways  of 3 5 km length are
required  to  harness  a  maximum  gross  head  of  200  m,  between  1520
masl and 1320 masl.
Baro 2 - Brief description of the recommended project
Project location, drawing Ba2-B01
Baro 2 is the downstream plant in the hydropower cascade on Baro
River Similar to the upstream Baro 1. Baro 2 is also a diversion scheme However, with 12 km it bypasses a much longer river reach than Baro 1
with 4 km
Baro 1 will run in parallel with Baro 2. and has a small reservoir with 2 m regulation, sufficient to provide necessary flexibility of operation The wa ter level of the reservoir forms  the tail water for the upstream Baro 1 scheme The total energy  generation of both plants  is  thus  governed by the overall head between the Baro 1 reservoir level and the tail water level of Baro 2 It is not influenced by the fluctuations in the Baro 2 res ervoir
Upstream of the dam site, the nver gradient is low and the valley opens up, so that a favourable elevation-capacity  relationship can be achieved with a limited dam height Downstream of the dam site the river be comes  very  steep with rapids, practically  along the entire reach that is bypassed by the Baro 2 waterways The selected dam site is thus con sidered to be the optimum one
With waterways of 12 7 km length the Baro 2 scheme harnesses a gross head of 510 m, between 1320 mast and 810 masl
Genji Diversion - Brief description of the recommended project
Project location. Drawing Ba2-B01
Genji River is a tributary to Baro River, joining the mam nver some 3 km downstream of the Baro 2 dam site As it drains a considerable catch ment, the inclusion of its discharge into the overall project concept ap pears advantageous
B»rcVoWw4A Geo^y -14 September 2006 aoc                            NORPLAN - NORCONSULT -LAHMEYERJV
in association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Waler Resources Feasibility Study of Bare 1 & 2 Multipurpose Projects
Volume 4 A Page 3-3
A desk study carried out in 2004 [3] showed that the diversion of the Genji flow to the Baro 2 scheme is technically and economically feasible provided that a market exist for the largely non-firm power that will be produced by this plant The study recommended a weir creating a mod est peaking reservoir, and an intake at Genji River on elevation 1190 masl some 1.5 km upstream of the confluence of Genji and Baro Rivers The valley is very narrow at the selected dam site, just between a steep downstream reach with rapids and a flat upstream section with a wider valley
A separate headrace waterway  system conveys  the Genji flow to the Baro 2 powerhouse Powerhouse cavern and tailrace structures  would then be used jointly by Baro 2 and Genji
With a headrace waterway of 5 9 km length the Genji scheme exploits a gross head of 390 m between 1200 masl and 810 masl, i e 120 m less than Baro 2 MPP
Ba to Volume 4 A
Geology M September 2006 aoc                       NORPLAN - NORCONSULT - LAHMEYER JV
m association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Watei Resources feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Page 4-1
4                          EXISTING INFORMATION
4.1
4.2
Maps, aerial photographs and satellite image
The following maps and aerial photographs have been used for the geo logical study and site investigations
•      Topographical  maps  1  50,000,  sheet  0835  C4  UKA  (covering  Baro 1) and sheet 0835 C3 SIBO (covering Baro 2)
•      Geological  map  of  Ethiopia  1:  2,000,000.  Geological  Survey  of Ethiopia,  Ministry  of  Mmes  and  Energy,  second  Edition  1996  Com piled by Mengesha Teferca el al
•    Geological map Gore, 1 250 000, Mengesha Teferra et al Ethiopian Institute of Geological Surveys. 1987
•      Aerial  photographs  1  50,000.  serial  no  VM  1370  PMW  AF-58-3 12APR67  R-284  photographs  30780  to  30783  (Baro  1)  antf  30692 to 30694 (Baro 2).
•      Aerial  photographs  constructed  by  Photomap  (K)  Ltd  ,  Nairobi, Kenya, for this Feasibility study senal no SAG II 2106 88 18
c Scale 1 40 000, photographs nos 7598 to7603
o Scale 1 10,000, photographs nos. 7507 to 7511 (Baro 1) and 7538 to 7546 (Baro 2)
•  Satellite  image  ‘Baro  Dam  Site,  Ethiopia"  Image  data  Landsat  7 ETM+.  Captured  5  February  2001  and  6  May  2002  Pan-enhanced image merge Spectral bands 4,5 3 RBG
Previous reports
Pre-feasibility  study  of  the  Baro  Hydropower  Projects,  Volume  4,  Nor plan - Norconsult, 1999
*
Baro volume *A Oolog, 14 Seolembe, 2006 doc NORPLAN - NORCONSULT - LAHMEYER JV
in association with Snebe'le Engineering and WWDSEFederal Democratic Republic of Ethiopia — Ministry of Water Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Pape 5-1
REGIONAL GEOLOGY - A SUMMARY
The Ethiopian plateau is  underlain at depth by  Precambrian crystalline basement successions  of the Northeast African-Arabian Shield covered in part by  Paleozoic  and Mesozoic  sedimentary  sequences  and tertiary to quaternary volcanic rocks The Mam Ethiopian Rift valley and the Afar Depression of Ethiopia, divide the Plateau into the Northeastern and Southwestern Plateaux  The Precambrian Basement rocks of the Ethio pian Shield crop out in four areas, that is  Northern Western, Southern and Eastern parts of the country, near the plateau margins The Western Ethiopia Shield where the project area is located is the largest of these exposures
The western Ethiopia shield is a mosaic of raised metamorphic gneissic domains separated by North-South trending belt of low grade metamor phic  rocks  that contain recognizable volcanic  and sedimentary  se quences. many  of which are highly  sheared and intruded by  diverse suites of plutonic intrusions In the Gore Map Sheet Mengesha and Seife (1987) recognized three major domains based on structural style, lithol ogy and metamorphic grade and referred to the Baro, Birbir and Geba Domains The Baro and Geba Domains consist of gneisses and migma tites al upper amphibolite metamorphic grade, where as the Birbir do main, lying in between them, is  a complex  lower metamorphic  grade rocks containing abundant mafic schists The three-hydropower projects are located in the Geba Domain Early plutonic bodies that are lenticular are recognized and are internally foliated and concordant with their host rocks There are also late more equi-dimensional and discordant intru sions
Further North, Northwest South and Southeast of the project area the Precambrian basement terrain is directly overlain above 1 600 m meter elevation by  flat lying, fine grained, aphiric, Tertiary  Basalt Flows  that have a preserved thickness of at least 250 m There is no evidence of Mesozoic Sedimentary rock deposits between the basalts and the un derlying Precambrian basement rocks  Thus  the marine transgression and regression that led to the deposition of sedimentary rocks elsewhere (mainly in the North and East) in the country, presumably did not reach here or were eroded away Thus the Tertiary basalt lava flows uncon- formably overlie the Precambrian rocks resting directly on them
Vesicular basali with large plagioclase phenocrysts, occurs  as  a scat tered outlier on an erosion surface at about 1300 masl in the valleys of Baro and Genji Rivers Only a few tens of meters of thickness are pre served and its correlations are unknown It is presumably younger than the plateau basalt succession
Vo/ume 4A - Geology
14 September 2006 doc
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Volume 4 A Page 5-2
Ftgure 5-1 Geological map Gore, scale 1:250.000, Mengesha Teferra et
al . Ethiopian Institute of Geological Surveys, 1987 Location of dam
sties shown
Explanations  regarding rocks  in project area in Figure 5-1 above Pgtr Syn tectonic  granites  Pgn4 - Hornblende-biotite and amphibole gneisses, granitic gneisses, etc ).
Volurna
GMiosy ■ MSeptember 2oo6dp-                     NORPLAN - NORCONSULT - LAHMEYER JV
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Volume 4 A
Page 6 1
6
6.1
GEOTECHNICAL INVESTIGATIONS - STRATEGY, METHODOLOGY AND PROGRAM
Strategy I procedure for geological mapping and site investigations
The  general  idea  has  been  to  address  important  geotechnical  issues necessary  to  demonstrate,  to  a  Feasibility  study  level,  the  technical  and economic feasibility of developing the scheme, with sufficient level of in vestigations   Initially   all   relevant   information   from   previous   studies   of Bare project area was reviewed and analysed A critical analysis of suffi ciency  and  quality  of  information  was  done,  related  to  the  actual  con struction works, where ground conditions may be critical for the design
Based on the available existing information, a "ground conditions expec tation model" was  developed, considering how the vanous  construction parts  are affected by  the character of the ground in this  process, key problems  were defined, also potential lack  of information in relation to Feasibility  evaluations  and design of the project Ground condition pa rameters  considered important for technical optimisation were defined A "ground conditions expectation model’ is a prediction obtained by evalu ating and analysing the available geological information and placing them in relationship to the project conditions  and demands  specified m the formulation of the ground conditions  issues  An expectation model is 
1
‘problem oriented '
and  available  information  is  structured  so  that  the
6.2
6.21
Baro Volume 4A
most  important  physical  conditions  (of  technical  or  economic  signifi cance for lhe project) are highlighted and presented in tangible terms
Site investigation program
Geological site investigations  for dams, tunnels, powerhouses  etc  . were aimed al assessing appropriate design parameters for these struc tures On basis of initial desk study and site inspection, a site investiga tion program was  concluded cornpnsing geological mapping, core drill ings  and laboratory  testing of soil and rock  samples  Planned refraction seismic  profiling was  regrettably  delayed due to time consuming proc essing of permission for use of explosives, and weather conditions. The seismic  investigations  had still not been executed at the preparation of this report.
During the implementation of the investigations  the "ground conditions expectation model' was  updated and. when necessary, remaining site investigation program was  adjusted By  this  approach, an optimisation of resources and time invested in the site investigations was achieved
Results  from the site investigations  are summarised and commented on in Chapter 7 Reports  with detailed investigation results  are enclosed as annexes Annex 4 A through Annex 4 F.
Geo/og/cai mapping
Geological mapping in the project area aimed at updating existing inter pretation on geology  This  mapping was  conducted by  senior geologists Mengesha Teferra and Molla Belaineh Mengesha had previous expen-
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in association with Shebelle Engineering and WWDSEFederal Democrats Republic of Ethiopia Ministry ol Waler Resources Feasibility Study of Bare 1 A 2 Multipurpose Projects
Volume 4 A Page 6-2
6 22
6 23
ence from this  area by  the geological mapping done for Gore geological map sheet (Me 36 “16} (Mengesha and Seife. 1987). He was  also in volved in the compilation of Geological map of Ethiopia (Mengesha et al, 1996) The report submitted by  Mengesha and Molta for the Baro Multi purpose Project is  enclosed as  Annex  4 F. Originally  the geological maps  and section drawings  in this  report showed terrain lineaments caused by  various  geomorphologic  processes. Based on aerial photo graph analysis  and engineering geological interpretation by  NORPLAN geologist A Halvorsen, the lineaments  have been replaced by  inferred weakness  zones. These inferred weakness  zones  may  effect the planned constructions  and do not include all the lineaments  shown on the original geological maps
Information  from  the  geological  mapping  is  also  discussed  in  Chapter  8
of this report
Seismic Refraction Profiling
Seismic refraction profiling had been planned for all three dam sites in
order to determine thickness of soil overlying rock and possibly extent of weakness zones The seismic profiling is a supplement to core drillings 
and give valuable information if the results are calibrated and considered together with the results of core dolling Unfortunately, the implementa
tion of the seismic profiling program was seriously delayed due to time consuming process of getting permits for handling and use of explosives 
and later on bad weather conditions in Lhe Baro area 11 was finally 
agreed to cancel the seismic profiling planned within this study as the
resulls could not any longer have any impact on lhe Feasibility Design
because of the delay
The results  of seismic  profiling would have improved quality  of lhe basic design information for the dam Because of the missing profiling, the dam design had to be based on conservative assumptions  on depth to bedrock, but lack  of profiles  has  not been decisive for selection of dam types etc.
The Consultant proposes that the seismic survey should be carried out
during lhe detailed design phase of the project Adjustments of founda
tion levels and minor adjustments on dam axis as well as dam cost could
then be consequence of improved accuracy of the ground condition
Excavation of lest pits
Test pits  for visual inspection as  well as  for collection of samples  for laboratory  tests  have been excavated at Baro 1 and Baro 2 dam sites Only  test pits  on the right side of Lhe river could be excavated because of unexpected inset of rams  and increase of river flow, which prevented crossing of the river. However, all test pits  necessary  for collection of soil samples  for determination of engineering properties  for evaluation of soil as  dam construction material as  well as  foundation conditions  could be excavated The missing fest pits  do not affect conclusion in the present feasibility  study  However, they  should be earned out during lhe detailed design phase of the project in order to increase accuracy of the design
Bare volume 4ft - Geology M September ?006 doc NORPLAN - NORCONSULT - LAHMEYER’JV
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Rotary core drilling
Volume 4 A Pago 6 3
6.2 4
Objective
Program
The objective of core drillings was to collect core samples of the materi als  in a practically  continuous  profile of the underground formation for assessment of weathenng thickness, lithological variation and variation in degree of fracturing of the rock mass Information on vanation in rock strength is  obtained by  laboratory  testing of selected rock  samples  In formation on variation in permeability  conditions  is  obtained by  packer testing or ’falling head’ tests m the boreholes
The core dnllmgs  for the Baro Multipurpose Project are listed in Table 6-1 As  results  became available, the dnllmg program was  reviewed and revised in order to obtain oplimal and cost efficient output from the drill ings
Table 6-1 Core drilling number and length of bore holes
Project area
Baro 1 Dam site Baro 1 I unncls Baro 2 Dam site Baro 2 Tunnels Genji Dam site Genji T unnel
Number of
bore holes
Total length dnlled. m
Total
7 381 8
6 558 2
4 151 9
6 772.7
2 81 2
1 100.4
26 2046 2
6.3
631
Rotary  core drilling was  sub-contracted to ARDCO - RODIO JV, of Ethiopia and Republic  of South Africa respectively, after the Client had requested proposals from international and local drilling contractors
Access by use of motonsed vehicles was not possible for some of the boreholes Therefore these drillings had to be carried out by use of heli
copter transport
Laboratory testing
Laboratory testing of soil samples
Soil samples collected from test pits have been examined and tested on behalf of ARDCO - RODIO JV in soil mechanics laboratory of Construc tion Design SCo Materials  Testing Department. Addis  Ababa ’Undis turbed block samples as well as disturbed bulk bag samples have been delivered for testing The laboratory testing comprised
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Volume 4 A Page B-4
63 2
>    Classification tests such as
Plasticity tests (Atterberg)
Grain seize distribution tests (sieve and hydrometer)
o Unit weight and moisture content
□    Linear shrinkage
o Content of organic matters
>    Compaction tests, (Modified Proctor)
>    Strength tests such as
n Unconfined uniaxial compression tests on undisturbed as 
well as recompacted samples
□    Consolidated tnaxial shear strength tests on undisturbed
as well as recompacied samples
o Direct shear strength tests on recompacted samples
>    Compressibility and swelling tests in oedometer
>    Permeability tests on undisturbed and recompacted samples
Laboratory testing of rock samples
Rock  mechanical testing has  been conducted on samples  collected from lhe exploratory  boreholes  The samples  were collected from the various types  of materials  encountered, in order to classify  the rock  and deter mine representative engineering properties  Laboratory  investigations were conducted on behalf of ARDCO-RODIO JV at the laboratory  of Construction Design S.Co as  well as  at the Ethiopian Geological Survey, Mineralogy  and Petrography  Laboratory  The laboratory  testing com posed
>    Petrographic analysis of thin sections on rock core samples
>    Un confined compression tests on core samples
x Potential Alkali Silica Reactivity tests (Mortar Bar Method) for consideration of the suitability for lhe use as concrete aggregates
Volu"* Geoto’* -14 Sepierrtw 2(Xi6 doe NORPLAN - NORCONSULT - LAHMEYER JV
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(v
Vdume 4 A Pag*6-5
6.4
Definition! - rock weathering
The following terminology (*) has been applied for the descnption of rock weathering and alteration and descnption of residual soils
Term
Unweathered, or Fresh
Description
No visible sign of weathenng Rock fresh, crystals bnght Few discontinuities may show slight staining
Slightly weathered              Penetrative weathenng developed on open discontinu ity surfaces, but only slight weathering of rock material Discontinuities are discoloured and discolouration can extend into rock up to a few millimetres from discontinu ity surface
Moderately weathered       Slight discolouration extends through greater pan of rock mass The rock is not friable Discontinuities are stained and/or contain a filling comprising altered mate rial
Highly (or severely) weathered
Weathenng extends throughout rock mass and the col oured matenal is partly friable Rock has no lustre All matenai except quartz is discoloured Rock can be ex cavated with geologist s pick
Completely weathered       Rock is totally discoloured and decomposed and in a fnable condition with only fragments of rock texture and structure preserved The external appearance is that of a soil
Residual Soil
Soil malerial with complete disintegration of texture, structure and mineralogy of parent rock
• Classification from the point of weathering recommended by the Geological Society of London (1970) and accepted by  U S Task  Committee for Foundation design Manual (1972)
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Volume 4 A Pago 71
7
7.1
7.2 7.2.1
RESULTS OF THE INVESTIGATIONS
General
In Ihis  chapter the results  of geological mapping, exploratory  drillings and laboratory  testing within Bara project area are presented and dis cussed The detailed investigation results  are presented separately  as annexes
Annex J 4 Rotary core dnihngs (ARDCO RODIO JV)
Annex 4 B Core box photographs
Annex 4 C Field permeability tests
Annex 4 0 Test pit logs
Annex 4 E Laboratory test results (ARDCO- RODlQ JV)
Annex 4 F Report from geological mapping by Mengesha and Molta
Annex  4  G  Seismic  Hazard  Assessment  at  Bare  Dam  Site  (Geophysical Observatory Science Faculty, Addis Ababa University)
This  chapter  includes  summaries  of  investigation  results  (factual  infor mation)  as  well  as  some  interpretation  and  discussion  of  the  results.  In terpretations  and  discussions  of  the  results  in  relation  to  project  compo nents and construction methods are included in Chapters 9. 10 and 1 Exploratory core drillings
General
Exploratory  core drillings  are listed tn Table 7-1 (Saro 1) and in Table 7-2 (Bara 2 and Genji) Their locations  are shown in Figure 7-1 to Figure 7-4 below as  well as  in enclosed -ED1 Bare 1 Project Area - Geological map, and Drawing Ba2-E0l Baro 2 Project Area - Geological map Detailed information, including core logs, is  enclosed in Annex  4 A. Core photographs are enclosed as Annex 4 B
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NORPLAN - NORCONSULT - LAHMEYER JV in association with Shebelle Engineering and WWDSEFigurn 7-2: Localton of Rotary coro drillings, lost pits (Now ’N’) and old TP from Profuasibtliiy study at Saro 1 darn
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Figure 7-3: Locations of rotary core drillings at Baro 2 and Genp project area
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Figure 7-4: Locations of rotary core drillings and now tost pits at Baro 2 dam site
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Page 7-6
Information from the exploratory dnllmg includes depths to bedrock and to ground water table, variation in rock  types  (lithology), degree of weathering fracturing / faulting of the rock mass (degree and character of fracturing) Detailed information is  shown in the borehole logs  in cluded in the report from the dnllmg contractor Annex  4 A Results from field permeability tests earned out dunng the dnllmg operation are in cluded m Annex 4 C
A summary of important parameters and information concluded from the core dnlhngs are given in Chapter 7 2.2.
Toble 7-1 Rotary core dnlhngs - Baro 1
SITE/ BORE
HOLE
NORTHING,
m
EASTING, m
ELEVATION.
m ail
Plunge/ azimuth, *
DEPTH DRILLED m
PERMEABILITY TESTS Packer (Falling Head)
B1D-1
890 894 51
758 956 11
1463 59
90
504
2
BIO-2
890 967 01
759 071 63
1520 41
90
503
2
B1D-3
891 107 63
759 277 90
1466 23
60 / N235E
70 4
5
B1D-4
891337 78
759620 21
1453 01
60/N55E
70 3
4*(1)
B1O-5
891511 79
759900 21
1526 20
90
804
(4)
Bioe
891799 78
758408 21
1539 73
90
30 1
•
Bl 0-7
890 806 13
758 866 56
1493 50
90
500
3
B1T-1
890 589 70
758 602 70
1497 00
90
500
(1)
B1T-2
890 916 08
758 307 30
1525 87
90
50 1
3
B1T-3
891 825 33
757 389 43
1577 44
90
160 9
4
B1T-4
892 628 23
757 103 03
1440 82
60/N190E
166 9
2
B1T-5
892 874 42
757 019 12
141508
90
80 1
3
BlT-6
893 333 56
756 965 25
1331 43
90
502
2
Total
940 1
30»(6)
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V&hjiTHi 4 A Page 7-7
Table 7-2 Rotary core drillings - Bare 2 and Geny
BORE
HOLE
northing.
m
EASTING,
m
ELEVATION,
m Ml
Plunge 7
•
depth’ OfiiLLE 0. m
PtPVEABiLlTY TESTS   Packer (FaanjHearft
BSD 1
997959 0
747411 0
1337 6
X
40 4 3
1
S2D-2
697949 0
747379 0
1320 6
90
399
2*0)
B2D-3
993196 1
7473483
1307 7
90
40 9
3-(D
B2D-4
89S428 9
747126 5
1315.7
90
305
1*<1>
B2T-1
899983 9
745879 0
1307 3
90
599
4
B2T-2
900838-5
745102 2
1303 5
60/ N
1009
5
B2T-3
902053 6
743928 9
1358 7
90
600
i*D)
B2T-4
902179.0
742837 5
1316 9
90
251 0
8
02T 5
903055 7
739772 B
1200 2
90
200 3
7
B2T 6
9030039
737602 4
1CB9 2
90
100 7
4
GJD-1
897190 0
744044 7
1201 8
90
40 1
3*(1)
GJD-3
897178 9
744722 0
1204 9
90
41 t
V(3)
GJT-1
B90392 0
745084 9
1232 6
60 i N200E
1004
4
Total
11082
46.(9}
7 22
Information on soil overburden, weathering and degree of fracturing
Summary  of information from exploratory  boreholes  on soil overburden, weathering and degree of fractunng. expressed as  RQD values  is shown in Table 7-3 (Baro 1 dam area), in Table 7-4 (Baro 1 tunnel area), in Table 7-5 (Baro 2 and Genji dam areas) and Table 7-6 {Baro 2 and Genp tunnel areas) The RQD values  are classified according recom mendation by  International Society  for Rock  Mechanics  (ISRM). from very  low (V L) to very  high (V H). and with percentages  of the various classes for the portion of the hole below the weathered zone
To vls^®,'se »he vanatton in RQD classes  between the various  bore- no es, the RQD-dass  percentages  are shown graphically  in Figure 7-5 to Ftgure 7-7. which also defines the RQD classes
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Tab/e 7-3 Bare 1 dam area - summary of information from exploratory
boreholes
1 Borehole Length, m
Soil thick-
nes% m
Assessed thickness                  Rock Quality Design,^
of zone with reduced
quality  due to weath
ering, m
RQD class            % of hole in rock
I
BIO-1 / 50 35
1
J
4 25
D VL
L
1M
H
___________ 0W-2J5Q24 1
VH
11
6
1
VL
L
M
H
VH
0
5
Tfi
0
77
1
fi
0
22
63
010-3/70 4
20
1
14
15
3?
21
| BID 4/70 2b
20
?
L
VL
L
M
H
VH
VL
L
M
H
VH
66
23
9
0
0
B1D-5/60 36
51 4
1
vT
L
M
H
VH
0
28
72
L°
0
B1D-6/30 12
55
1
2
31D-7/50 Di
44
1
24
VI
L
M
H
VH
VI
L
M
H
VH
.
3
0
21
0
76
0
4
0
13
S3
Baro Wd™ <A GM<W ' 14 SePtsr7lbttf 20ft> (,oc
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Volume 4 A Page 7-9
Table 7-4 Baro 1 tunnel area - summary of information from exploratory
boreholes
Borehole
no, /
Length, m
Soil thick-
Hess, m
Assessed thickness of zone with reduced quality due to weath
ering, m
Rock Quality Designation
RQD class
% of hole in rock
B!T-t / SO 05
54
00
VI
L
M
H
VH
33
11
2
2
52
R'T-2/50 1
94
10
VL
L
M
H
VH
0
3
14
32
51
91T-3Z '60 9
31
1T
VL
L
M
14
VH
0
4
12
12
72
BlT-4/
166 fl 5
8 35
o
VL
L
M
H
VH
0
0
a
7
S3
au-s^aoj
20
10
VL
L
M
H
VH
0
9
23
26
42
B1T-6 ■ 50 17
19B
o.a
V.L
L
M
H
D
2
D
0
1
I
I
V.H
95
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Volume 4 A Page 7 10
Table 7-5 Bam 2 and Genji dam areas - summary of information from exploratory boreholes.
Bo
„
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Volume 4 A Page 7-11
Table 7-6 Baro 2 and Genji tunnel areas - summary of information from
exploratory boreholes
Borehole
no. /
Length, m
Soil thick ness  m
-------—?--- ■—
Rock Quality Designation
r
Assessed thickness of zone with reduced quality due to weath
ering. m
ROD class
% of hole in rock
02T-1 / 59. &6
' 11.0
10 0
1 VI
L
M
H
VH
T2
2D
TB
29
19
B2T2 i1
100 05
9.0
* 3H
VL
L
M
H
VH
15
12
8
6
59
02T-3 / 60 04
40 5
20
VL
L
M
H
VH
0
5
30
0
65
B2T4 <■
250 99
4 €5
Section 1 & 0 - 24 o 11
boundary basaB gnem
VL
L
M
H
V.H
3
2
5
24
M
B2T-S 200.3
67
0B
VL
L
M
H
V.H
0
i
13
S3
02T-S/
10C 69
TO.4
71
VL
L
M
H
V.H
1
0
15
12
72
GJT-1 f
?M 44
—  J
9.0
10
VL
L
M
H
VH
4
5
1
24
66
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Baro 1 dam site. RQD classification
Volume 4 A Page 7 12
RQD class
Figure 7-5 Distribution of RQD values in boreholes B1D-1 to B1D-7 with reference to classification by International Society of Rock Mechan ics (ISRM)
Baro 1 - tunnels. RQD dissipation
Figure 7-6 Distnbution of RQD values in boreholes B1T-1 to B1T-6 with reference to classification by International Society of Rock Mechanics (ISRM)
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3aro 2 and Gvnji dam sites, RQD dais iff caiiori
Vo'um-e 4 A Page 7-13
Ftgure 7-7: Distribution of RQD values in boreholes B2D-1 to B2D-4 GJD-1and GJD-3, with reference to classification by international Soci ety of Rock Mechanics (ISRM) It should be noted that only the gneiss section below depth 2dm is included in B2D-1
Haro 2 and Ganjl Tunnels, RQD classification
1DC 90 SO 7C 60 50
40
30
20 10
0
50 75
Median*
RQD classes
Figure 7-8 Distribution of RQD values in boreholes B2T-1 to B2T-6 and GJT-1, with reference to classificafron by /ntemabona/ Soc/efy of Rock Mechanics (ISRM)
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Baro 1 boreholes
Dam area
Geological map Drawing Ba1-E02 Geological section Drawing Ba1-E03
Overburden Soil
Weathering
Lithology
Fracturing
The area is tn general soil covered but with rock exposures at river banks and in river bed Soil thickness m the boreholes varies from about 4 m in B1D-1 to about 51 m in B1D-5
The soil is generally residual soil decomposed from gneiss, except the soil encountered in the upper gneisses and amphibolites have been en countered  in  the  boreholes  For  more  detailed  information  see  core logs Annex 4 A. and core box photographs. Annex 4 B Results of lithological microscope analyses of thm-sections are described in Chap ter 7.6 2 and in Annex 4 E
Thickness of zone with pronounced weathering (highly or severely weathered material), below what has been defined as part of borehole
B1D-5 as well as test pits B1-NTP-D-4 and -5 At these locations the re sidual soil is decomposed from basalt Colluvial soils are found at some locations both sides of the river
Quartzo-feldspatic  gneisses, micaceous  gneisses  and amphibolites have been encountered in the boreholes For more detailed information, see core logs, Annex 4 A. and core box photographs. Annex 4 B Re sults of lithological microscope analyses of Ihin-sections are described in chapter 7 6 2 and in Annex 4 E
Degree of fracturing in the core samples is reflected by the RQD value, shown graphically in the core logs. Annex 4 A A statistical compilation of RQD values  is  shown in Table 7-3 with graphical presentation in Figure 7-5
RQD-values  are  high  for  boreholes  B1D-1,  -2.  -6  and  -7,  with  values classified as high and very high of 76% or more Boreholes B1D-1. -2 and -7 are located in the west-south-western part of the dam area, on the left side of the nver Borehole B1D-6 is located at a potential quarry site, in the order of 1 2 km direct distance from the nght nver bank at the dam site
RQD-values are especially low for borehole  B1D-4. located at the right side of the nver, with rock strongly fractured and partly crushed and with RQD values characterised as low or very low for more than 90% of the hole within rock The results form B1D-4 could indicate that the borehole is within the fault zone(s) crossing the river. These zones are indicated on the geological map, Ba1-E02. In boreholes B1D-3 and -5 RQD values are in general intermediate
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Feasibility Study of Bare 1 & 2 Multipurpose Projects
Tunnel area
Geological map:             Drawing Ba 1-E01 Geological section: Drawing Ba 1-E04
Volume 4 a Page 7-15
Soil overburden Liolhology
Weathering
Fracturing
72 4
Overburden
Soil
Lithology
g roVolume4A • Geology 
The area is  in general soil covered though with exposed rock  in steep terrain. Soil thickness  in the boreholes  varies  from about 2m in B1T-5 to about 20 m in BlT-6.
Quartzo-feldspatic  gneisses, micaceous  gneisses  and amphibolites have been encountered in the boreholes. For more detailed information, see core logs  Annex  4 A and core box  photographs  Annex  4 B Re sults  of lithological microscope analyses  of ihin-sections  are described in chapter 7 6 2 and in Annex 4 E.
Thickness  of zone with pronounced weathering (highly  or severely weathered material), below what has  been defined as  soil in Table 7-1 vanes  from 0 m in borehole B1T-4 io 8 m in borehole B1T-1 The poor quality  of this  upper section of rock  in B1T-4 is  possibly  a combination of tectonic disturbance and weathering
A  statistical  compilation  of  ROD  values  is  listed  in  Table  7-3,  with  graphi cal presentation in Figure 7-5
RQD-values  are in general high for boreholes  B1T-2, -3, -4 and -6. with RQD classified as  high and very  high for more than 80% of the hole lengths in rock.
In   boreholes   B1T-1   and   -5   RQD   values   are   characterised   as   intermedi ate.
Bara 2 and Gen/r bevehotes
Baro 2 Dam area
Geological map; Drawing Ba2-E02
Geological section: Drawing Ba2-E03
Thickness  of soil cover is  variable, with partly  exposed rock  al riverbanks and in riverbed and thicker soil cover away  from the over Soil thickness on the right side of the river is  shallow from 0-6 m. whereas  the soil con-
dlflor,s   are   Qwte   different   on   the   left   bank   where   the   soil   thickness   is   16
m in B2D-2
n eft bank the soil is generally residual soil decomposed from gneiss 
ome alluvial material is found in lhe bed of a tributary entering the Baro
iver just upstream of the planned dam On the left bank, the soil is 
; h/ uv,al and Pan'y residual decomposed partly from basalt and
partly from gneiss (at lower parts close to the river)
In B2D-1 basalt was encountered above the gneiss formation with own ary at depth about 28 m, or somewhat higher Due to very high
a
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in association wilh Shebeile Engineenng and WWDSEFederal Democratic Republic of Ethiopia Ministry of Water Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Page 7-16
Weathering
Fracturing
Overburden
Soil Lithology
Wealhenng
Fracturing
core loss, the exact location of the boundary  is  somewhat uncertain The gneiss  below the basalt in this  hole, as  well as  in the other holes  is in general of quartzo-feldspatic, and partly  micaceous  composition For more detailed information see core logs. Annex  4 A and core box  pho tographs  Annex  4 B Results  of lithological microscope analyses  of thin- sections are described m chapter 7 6 2 and in Annex 4 E
Weathering  thickness  at  the  Baro  2  dam  site  is  highly  variable,  from  0  m in  boreholes  B2D-3  and  -4,  on  the  right  side  of  the  river  to  21  m  in  the upper  borehole.  B2D-1,  on  the  left  side  of  the  river  Some  sections  of basalt  in  the  upper  part  of  B2D-1  are  slightly  to  moderately  weathered but  the  general  rock  quality  is  though  poor  down  to  the  top  of  the  gneiss at depth 28 m
A   statistical   compilation   of   RQD   values   is   shown   in   Table   7-5.   with graphical presentation in Figure 7-7
RQD-values  are in general high, with RQD classified as  high and very high for more than 69% of the hole lengths  in rock  The RQD values  for B2D-1 represents the gneiss section below the basalt
Genu Dam area
Geological map             Drawing Ba2-E01
Geological section Drawing Gen-E01
Thickness  of soil cover is  variable, with partly  exposed rock  at river banks  and in river bed and thicker soil cover away  from the river Soil thickness in borehole GJD-1 is about 3 m and in GJD-3 about 5 m
The soil is mainly residual, decomposed from gneiss
The   rock   encountered   by   the   core   drillings   at   the   Genji   dam   site   is mainly quartzo-feldspatic gneiss
The  highly  weathered  zone  is  thin  less  than  1m.  both  m  borehole  GJD-1 and in GJD-3
A  statistical  compilation  of  RQD  values  in  the  two  boreholes  is  shown  in Table  7-5,  with  graphical  presentation  in  Figure  7-7  RQD-values  are  in general very high 94% and 93% of the holes classified as very high
Barp 2 and Genu Tunnel area
Geological map
Drawing Ba2-E01
Geological section Baro 2 Drawing Ba2-E04
Geological section Genji. Drawing Gen-E04
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in association with Shebelle Engineering and WWDSEFederal Democratic Republic at Ethiopia - Ministry d Waler Resources feasibility Slurfy of Ba<o 1 4 2 Multipurpose Projects
Volume 4 A Page 7-17
Overburden Lithology
Weathering
Fractunng
7.3
The area along the tunnel alignments  is  in general soil covered In gen- eral the soil thickness  varies  from less  than 5 m (B2T-4) to 11 m (B2T-
1). with exception of B2T-3 with more than 40m
Basait was  encountered in upper part of borehole B2T-4, with boundary towards  the underlying gneiss  at depth 19 m Possibly  the decomposed matenal found in the upper part of boreholes  B2T-2 and B2T-3 is  also derived from basalt
The composition of the Pre-cambrian rocks  vanes  from the upstream part of the tunnel area including Genji area to the downstream part In the boreholes  in the upper and central part of the area lhe rocks  en countered m the boreholes  are quartzofeldspatic  gneisses  with variable content of biotite In the area towards  the outlet, the rocks  are of a more mafic  composition, with mainly  amphibolite or metagabbro in borehole B2T-6
For more detailed information, see core logs, Annex  4 A, and core box photographs  Annex  4 B Results  of lithological microscope analyses  of thin-sections are described m chapter 7 6.2 and in Annex 4 E
Thickness of the weathered zone below what has been defined as soil
overburden in Table 7-6 is small, with maximum of about 10 m in bore
hole B2T-1.
A   statistical   compilation   of   RQD   values   is   shown   in   Table   7-6   with graphical presentation in Figure 7-8
RQD-values  are in general high for boreholes  B2T 4, -5, and -6 GJT-1 with RQD classified as  high and very  high for more than 84% of the hole lengths in rock
In   boreholes   B2T-1,   -2  and   -3,   RQD   values   are   characterised   as   inter mediate
Permeability conditions
In’Situ permeability  of rock  has  been determined by  the use of "falling head method or by  waler pressure testing of sections  of the boreholes Test sections  have been confined by  use of single packers  The pres sure has  generally  been applied in steps  by  use of pumps  and controlled by  manometer, whereas  the water take has  been measured by  flow meter The test sections  have been selected based on consecutive evaluation of the drilled cores  and other information from the drillings  as drilling operation proceeded Test intervals  were selected in order to be representative for permeable sections  in the borehole, i.e jointed or crushed zones  A summary  of permeability  test results  is  presented in Table 7-7 to Table 7-12 below The tables  show the lowest and the highest recorded values  at each single test as  well as  the calculated mean value of all readings  in a test. The values  shewn in the column
Recommended’ are based on an evaluation of each single step of the lest and possible errors  during testing (see diagrams  presented in Annex 4 C), and are values  recommended for design calculations  Details  on each and every lest are presented in Annex 4 C
0art>VDiun^M Geology 14                 20C-S aoc NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Water Resources feasibility Study oF Bare 1 & 2 Multipurpose Projects
Volume 4 A Page 7-18
Variations
The results are presented according to
•      Lugeon Method, where
1 Lugeon = 1 litre water lake per minute per 1m section of the bore
hole at pressure 1 Mpa (=10 bar)
•      Darcy's law, where
Permeability coefficient = k [m/s]
The results  in Table 7-7 Io Table 7-12 below show thal lhe permeability of the rock  mass  is  generally  low to very  low In some sections  of exten sive jointing or crushing relatively  high permeability  has  been measured The highest permeability  has  been measured in jointed zones  at lhe up per part of dam foundation Leakage prevention measures  by  cement groutrng have to be made in these zones at both dam abutments
Bun? Volume 4A - Geology *4 September 2006
NORPLAN — NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSEFederal Domocrabc Republic of Ethiopia - Ministry of Waior Resources Feasibility Study of Baro 1 & 2 Multipurpose Project*
Vc/unu? 4 A Page 7-19
Table 7-7; Summary of field permeability test results for Baro f Dam Area
I.
Luegon Values
Coeff. of permeability k [m/s]
Comments;
I Bore
hole no.
Test     Sec tion [mJ
Material
High
Low
Aver
age
Recomm ended
High
Low
Aver
age
Recomm
ended
B1D-1
6.5-16
Slightly weathered amphibolite
100
9.4
9.5
9.4
1 4t-O6
1 3E 06
1.3E-06
1.3E-06 '
RQD=75-100%
B1CM
35-50
Frosh amhlbolite- and gnetss
0.0
0.0
0.0
0.0
O.OE+OO
O.OE+OO
O.OE+OO
0,OE*00|
ROD=100
B1D-2
19-27
Quarz feidspatic gneiss
4.0
2.6
2.6
3.9E-O7
2.0E-07
2.7E-O7
27E-07 |
RQD-100
B1D 2
27-39
Quarz feldspatic gneiss
0,5
0,3
0.4
04
5.2E-0B
3.7E-OB
4.3E-OB
4.0E-08
RQD = 100 exccp! 26-30rn RQD=75
01D-3
21-29
Quarz feJdspabc gneiss
23.7
6.5
13.0
10,0
2 6E-06
9.9E-07
1.4E-06
1.2E-05
RQD^85'100 from 23rn
010-3
29-36
Quarz feidspalic gneiss
00
0.0
0.0
o.o
O.OE*QO
0 b0E*O0
0.0E+00
0.0F*00
RQD=100
BIO-3
37-45
Quarz IcIdspaUc gneiss
0.0
0.0
0.0
0.0
O.QE+OO
0.0E+00
0.0E+00
O.OE+OO
ROD =40-50%
S1D-3
46-56
Quarz fddspabc gneiss
0.1
0,0
o.o
0.0
6.3E-O9
2.0E-09
3.GE-O9
3.0E-09
ROD = 50-70 RQD-0 54-56m
B1D.-3
56-70
Quarz feldspatJc gneiss
0.0
0.0
0.0
0.0
0,OE*OO
0.0E+00
O.OE+OO
0,0E*OC
ROD- 60-70, excepl 61.5-63,5m
10%
01D-4
17.5-22
Medium grain sand (decomp gnetss)
1.SE-07
1.5E-07
Falling Head test (soil |
01D-4
23-30
Quarz Teldspatlc gneiss, fractures
36
2.3
3.0
3.0
3.5E-07
r 2.1E 07
3.0E-07
3.0E-07
RQD varies 0 - 50%
B1D-4
30*40
Quan feldspalic gneiss, fractures
0.0
0.0
0,0
0.0
O.OE+OO
5.9E-10
O.OE-+DO
2.0E-10
RQD-20
B1D-4
40-50
Quarz leldspauc gneiss
0.0
0.0
0.0
0.0
3.4E-09
0.0E+00
1.6E-09
1 OE-09
RQD= 0-40%
Bl 0-4
50-70
Quarz feldspatic gneissZampbibollte
co
0.0
0,0
0.0
6.0E-10
2.0E-10
4.0E-10
4.0E-10
RQD varies 0-50%
BlD-5
9.6-21
Silty day
3 0E-07
r
3.0E-07
Falling Head lest
B1D-5
23-32
Silty day
1 b3E-07
1 3E-O7
Falling Head test
Bi 0-5
33- 38
, Silty clay
2.3E-O7
2.3E-07
Falling Hoad lost
01D-5
40-47
Silty clay
9.9E-QB
1.0E-07
Fading Head lest
BlO-7
7,5- 16
Quarz feldspaiic gneiss
26,7
5.0
16.5
16.0
2.5E-06
4.6E-07
1.7E-O5
2.0E-06
RQD=80-100
B1D-7
16-31
Quarz feldspalic gneiss
0.0
0.0
0.0
00
0.0E+00
o.ot*oo
O.OE*DO
O.OE+O0
RQD' 100. except 24-26m:RQD=B0
B1D-7
30 50
Quarz feldspahc gneiss
0.1
—
0.0
DO
0,0
2.0E 08
0,0E*QO
O.OE*QO
O.OE+OO
RQD-100
Bare Volume 4A . Geology • 14 September 2006 .doc
NORPLAN - NORCONSULT - LAHMEYER JV
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Volume 4 A
Page 7-20
------------------------- Tab/e 7-6.- Summary of field permeability test results for Bare 1 Tunnel Area
Luegon Values
Coeff. of permeability k [m/s]
Comments;
□ore
hole no.
Test     Sec tion [m]
Material
High
Low
Aver
age
I Re- comm* ended
High
Low
I Aver
age
Re
comm ended
B1T-1
8.7 - 19.4
Quarz bilolite gneiss frac- luredi'fragnientBc
3.9E-O0
4.0E-00
Falling Head lesi
B1T-2
12.2-20.1
Quarz teiaspatic gneiss
0.0
0.0
0.0
0,0
0OE+OO
□ OE+OO
O.OE+OO
0 OE+OO
ROD-100
01T-2
20-30
Quarz feldapallc gneiss
0.0
0.0
00
0.0
Io 0E*OO
O.OE+OO
O.OE+OO
OOF+00
ROD--85-100
B1T-2
30-50
Quarz feldspar gneiss
0.1
0.0
0.1
01
1.4E-09
Q.0E-W
| 9.6E-10
1.0E-09
ROD-100, except 31-33/43-49
ROD=85
B1T-3
SO- 100
Fe dspatic-biotil gneiss
0,0
00
0,0
0.0
0OE+OO
O.OE-OO
O.OE+OO
O, OE+OO
RQD=100
B1T-3
WO - 125
Feldspaiic-biobt gneiss
0.0
0.0
D.O
0.0
2.2E-09
0 0E+00
4 &E-TO
1.0E-09
RQD=100
B1T-3
125-150
FeidspaiK-bioiit gneiss
0.9
03
0,5
G.6E-08
4 2EW8
5 4E 00
5.4EW8
RQD-TOO. RQD=70 from T37-140m
B1T-3
151 - 161
Feldspatlc-bloiit gneiss
2,5
0,5
1.2
1.2
1.6E-07
4,6E-08
fl.fiE-flfl
0 0E-08
RQD=100
B1T-4
85-101
Fekrspalic-tMoli t gneiss
0.1 *
0.0
0.1
0,1
B.9E-O9
1 7E-O9
S.flE-09 |
5.8E-O9
RQD varies 85-100
B1T-4
116- 126
Fflldspalic-biDtll gneiss
122
8.4
10,4
10,0
1 6E-06
1.2E-06
1.4F-O6
1.4E-06
RQD=l00
B1T-5
40 56
Fresh dark smhibolile
o.a
0.3
0.6
06
1.3E-07
----------------1 4.9E-0B
9.SE-08 1
96E-08
RQD va^es 20-90, average approx 
W
1
! BIT’S
52-71
GreenWpinc amphibolite
0.0 '
0.0
0.0
0.0
O.OE+OO
O.OE+OO
□ ,0E*0O
O.OE+OO
RQD-100
01T5 JJ
52-80
G-monish/pInc amphibolite
0.0
0.0
0.0
0.0
O.OE+OO
O.OE+OO
O.OE+OO
O.OE+OO
RQD=100
B1T-6
21 ■ 32
Quartz teidspatic gneiss
0.0
0.0
0.0
0.0
O.OE+OO
O.OE+OO
o,oe+oo
O.OE-OO 1
RQD-100
B1T-6
35-50
Quartz feldspahc gneiss
0.5
0.2
0.3
0.3
5.9E-08
1.0E-O8
3.9E-OB
3.6E-08
ROD-100
Ba*o Volume 4a . Geology - 14 Scplembef 2006 Ooc
r___
NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSEFederal Democratic Republic ol Ethiopia - Ministry of Water Resources Feasibility Study o! Baro 1 & 2 Multipurpose Projects
Volume 4 A Page 7-21
Table 7-9: Summary Of field permeability test results for Barn 2 Dam Area
Luegon Values
Coeff. of permeability k [m/s]
Comments;
Bore
hole no
T est Sec
tion
Material
High
Low
Average
Recomm
ended
Low
Average
Recomm ended
020-1
18-25
Completely weathered gneiss
35,7
21.4
28.9
30.0
2.9E-06
2. IE-06
2.5E-O6
2.5E-06
RQD-0
B2D-1
21.7-31
Completely we al her ed gneiss
23,1
15.5
187
19.0
L.---------- -----------
_________
4.7E-07
2 CE-06
1 6E-06
1.7E-06
1 7G-06
RQD=0
020 1
30 40
Moderately wealhered-fresh
gneiss
44
2.0
3.2
32
2.1E-07
3.5E-07
3 5E 07
RQD=70 to 100
| 02D-2
07-75
Clayey sandy sill (residual sori?)
2.5E-07
2.SE-Q7
Falling Head test
B2D-2
12 20
Transition soil - fresh gneiss
3.3E-O7
3 5E-O7
Falling Head lest
. B2D-2
21 -30
Frosh dark amphibolite
1.1
0.0
0,6
0.5
1 1E^O7
D.QE+00
6 2E-08
7.0E-08
ROD vanes 75-100%
B2D-2
30-40
Fresh dark amphibolrte
0.2
0.0
0.1
0.1
2.BE-08
OOE+OO
9.6E-09
1.0E-08
RQD=100
B2D-3
3,0 -6 1
r
Reddish soil (sand & day)
3 7E-08
5 0E-D8
Falling Head test
020-3
10 22
Quarz-bolite gneiib
0.3
0.1
0.2
0.2
5.0E-O8
8.2E-O9
2.7E-08
2.7E-DB
RQD=100
B2D-3
2D - 31
Quarz-biotite gnetss
0.1
0.0
0.0
0.0
6 2E-09
O.OE+OO
I.2E-09
t.0E-09
RQDMOO
02D3
30-41
Quarz biotite gneiss
0.0
00
0.0
0,0
fl.OE+OO
O.OE+OO
O.OE*UO
O.QE’OO
RQD-100
02D-4
0 5-2.5
Reddish brown soil
S.5E-O7
5.0E-07
Falling Head test
B2D4
7-16
Quarz-ferdspatic gneiss
0.1
0.0
0.0
0.0
1.8E-08
O.OE+OO
4.4E-09            5.0E-09
RQD=100
__ __________ —_____ i
Harq Vgiume 4 A Geology - 14 Septemtw 2006 doc
NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSE-i—u
Volume 4 A
Page 7-22
Jjb/e 7-10 Summary of field
oat See-
L Lon
Luegon Values
Comments;
Aver ago rRccoarn-
Coeff. of permeability k (m/s]
Ave raqo       Rcconwn-
4»4E“04
B2T-1
B2T-1
B2T-2
B2T-2
B2T-2
B2T-2
B2T-2
B2T-3
B2T-3
B2T-4
B2T-4
B2T-4
B2T-4
B2T-4
02T-4
02T-4
B2T-4
Fresh bxotue fold spa tic
_______________
F •        ««*         biotite         feJdspntP’ 9 n e i j
4.CE
7F.-06 4E-O8
i,SE-Ut 2.38-              J.£E-2fi
Fresh 
gneiss
rresh gneiss
biotite
2E-0R
»-jC<10C, excel - 44,7-43,6m
RQD-30
biotite
toldsp.itir
tcl-ispatic
1.5E06                  varies 40-90*
i,7E Lt-       HQ 13 vanea ‘•C-904
5.5F-06       HQD-SQ nt 4U-b~“. udl HJD spprox -------------------------------------—___
2,2E-0R
3, 6E- H.4E-07
3.28-08 4——
a 4. K-0ft 78-07
4, T
HUD-10., except 67-97m6: RQt7»3?
Frosh           bir.titc           FeTdspotTc gneiss
fresh  biotite foldspa*,  ic
t.CE Q7         RQD-103 ti n *2 77m. RQD-K 77-tt2a
gneiss
Fregr
gneiss
biotite
feldspati
F -0         1.5t 0t                      bE-
. , bL-C’’ 8. lL-'t? 1.IE-07
Peddish           xcdsldual           clayey aoi 1
•rj.etcly weathered gneiss Frost, ti »tite teTdspa"* I gneiss
Fresh biotite foldspatic one ion
2.LE-J7
5, M2-0B
RQD-10    lr-m    7S-bJm    rest    K.n    gone ally IQO
Ru::-ir ‘
i a
: Head test
2. I Cb
7E-0 * 4.4E-0 '
3E- 37
2.et-07
4.8E-07
6E- 2-7
i, -oe
>E-06
:e-o% BJ
I.4K-0?       RQb’Siu -*00%
3."E-37
4. OE
F
*' . except 129-1 • 
n 0 - •
Fresh 
blot
itfc.dttp.iti
gno is a______             ___
F         resh         biotite         'fcIdsp.itic qnclss
•. 68 C
V.
Fresh             biotxt*’ gncins
Fresh 
gneiss
Fresh 
biotite
biotite
teldspatic
fejaspatic
tcldspatlt
2«l£-0/ 1.2E-07
2.IL-07 IE
4. 3E ’
..2E-07 i.et-ca
HQti-lCb,  excep’ tew «e-ti.r >rp,-go-
•JC
R .. - ’            - • op I ■ - -        ■- • . RQI -80 90 
bQC-173, except '.92 IHbrti RQU-75 HQD-inO, nxcopt .26-Z79t* RQb-•
rx npt
onc iss _________ _________________ t test biotite lcLdspatlc gneiss
Bare Volume 4A • Gooioqy • 14 September 2006.doc
NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSE
<Federal    Democratic    Republic    of    Ethiopia    -    Mbnislry    of    Wale*    Resources Feasibility Study ol Baro 1 & 2 Multipurpose Projects
VoJurnc 4 A Page 7-23
Table 7-11: Summary of field permeability test results for Baro 2 Tunnel Area (Continued)
Luegon Values
Coeff. of permeability k [m/s]
Comments;
Bore hole’no.
Test Sec
tion
Material
High
Low
Aver
age
Low
Comm
ended
Aver
age
Re
comm ended
B7T-S
79 - [01
HtzJrrdLely     -tiuilh.     feldsf     . -inciiits
1,4
1,0
1,2
.2
1.9E-Q7
1 2E-07 |
r
l,5E-Q7l
J
oM. 07 '
B-QE-’Jil i00 exciipr fl’ -02r.iHQu-fl5
r
azT-s
110        130
H-ndtirJLely weath. feldsp.
innn
0,7
0,4
0,<
D/6
9.3E-08
5, 2E-U?
7, bF.-DH 1
*,€£-• h
ftQD-100
0ZT-5
130 ' 150
Qua      rz-biotite      gneiss,      well to! Uted
0.5
0,4
0,3
Qi 5
?.4E-QB
6 It O»
r
6.0E-1B
SBE-39
KQU-100, except L44 - 147ri: HQD-7 5
92T-5
151 ■ 172
Qujti         biotite       gneiss,       well falLaird
0,3
0,2
0,3
0,3
4,4E- Jti
2, «E-Dfl
________
1,9E-08
i t -1E-C5
RQl.-LOQ
B27-5
370 - 151
Quait-bio:       ire       gn»iu.       well lai .died
0,4
0,2
- —------------- 4
2,3
0. 3
•l,7t-18
2.&E-CB
J.9E-5&
J. lb 06
RQD-'IUO. except L7,'-I74®i; RQL.-75
92T-5
15) - 192
Quara-biotite          qnelss,          well fol a>j led
0,9
0,5
0,7
0,7
1j2E-07
£,9E-08
3,0E-“£
9. --0B
ROD varies ED-IDO 4
B2T—5
190 • 200
Quarz-biotite gneiss, well
f ulidled
1,4
0.9
1,2
1,2
l,9E-07
1,2E-Q7
1.7E-G'
RQD vanes 50-100*
327-6
50 - 70
Dark greenish amphibolite
1,3
1,0
1,0
ir
d,OK-08
7,IE-00
7.7E-3B
7.7E-38
RQOIDO
02T-6
70       80
7ark greenish amphxb-litc
0,0
0,0
0,0
0,3
0,QE*C0
0,0E»0O
thCEkOa
DE+03
RQb-100
H2“-6
80 - 90
Dark greenish amphibolite
0,0
0,0
0,0
c,o
D.OEtQO
0,QE+QD
0.0E*00
•3, Ge *0(j
RQD-IOC. except B5-97m; RQU-SO
H2T-6
90 - 101
□ark grrrnlah amphibolite
0,0
0,0
0,0
M
O'QE+QO
0,lE+OU
ij,jE*Q0
I
hioti
RQOIOC
Bare Volume 4A ■ Geology -14 September 2006.doc
NORPLAN - NORCONSULT - LAHMEYER JV
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IVolume 4 A
Page 7-24
Table 7-12: Summary of field permeability unt^eaustimrye lsuew rltes sufltos rr uGt ueennp jilDam and Tunnel Dam Areas
jam diiu r L/rrnvr uani
■B
Luegon Values
Coeff. of permeability k [m/s]
Comments;
core
hole no. | i1
r est Section
Material
High
Low
Avera
ge
Re
comm ended
Low
Average
——
IGJD-l
Re
comm ended
Highly leathered/ f re ah gneiss
2,4E-07
2.4E-
fallinq Head test- RQD«0-100
' GJD-1             1
10 - 25             *
Fresh quartz feidspatn gneiss
3»1
0,0
3,0
0,0
2,IE-09 | 0,OE*00
5,3E-’.O
5. E-10
RQD 100
GJO-1
20 -34
Fresh quartz fcldspatic gneiss
0,0
0,0
0,0
o.c
C,3E*0C
0,OE*00
0,CE-00
0,DE«CC
RQ3 IOC
GJO-1
3: - 40
Fresh quartz fcldspatic gneiss
0,0
0,0
0,0
0,0
5.CE-O9
0,0E*0O
1,OE-IC
",CE«CO
RQQ LOO
GJ 0-3
3 - 5.0
Weathered biotite fcldspatic
qnciss
■
2,6E-07
2.6E 07
Falling Head test. FQD=0-100
gjo-v;
10 - 22
Biotite 'rldspat;- gneiss
Biotite fcldspatic gneiss
3,2
i, •
2,2
2,2
3.2E-07
2,DE-07
7, 6E-07
2,6E-07
RQD-130, except 14-l€ra: R0D-704
CJD-3
22 - II
0,0
0,0
0, j
0, o
0, OE-fOll
0,OE»CO
0,OEIOO
o.oe^oo
RQD-100
GJC-3
31 - 41
Fresh quartz fcldspati gneiss
o<:
0,0
0.0
0,0
0.0E*C0
0,OE+00
0,0E*0D
0,DE♦0G
RQD-100
G JT- 1
SO - ?1
Quartz biotite gneiss
0, c
0,0
0.0
0,0
4, tiE-09
0,CE*CO
1,3E-09
I,3E-O9
HCD’lOQ
GJT-1
70 - 82
Quartz-biotite qncxss
0,1
0,1
0,1
0,1
1,9L-C0
9,2E-0’»
L,3E-OR
:,3E na
ROD-100
GJT-1
80 - 91
Quartz-biotite gneiss
0,2
0,1
0,2
c,2
3.5E-08
1 1.7E-08
2.€F.-03
2,6E-OH
RQD-100 - (85 in section)
GJT-1
9’.        103
1junrtz-biotiIt gneiss
0,4
1
0,3
3, )
. 5.5E-Q9
i 4.0E-08
4. FE-08 
1 
4,7E-OB
RQU-1GC - (95 in section)
* ---------------------------------------------------------------------Federal Democratrc Republic of Ethiopia — Ministry of Waler Resources Feasibility Study of Baro 1 A 2 Multipurpose Projects
Volume 4 A Page 7 25
7.4
Ground water
Depths  Io the ground water table were measured in the exploratory boreholes  al the start of the shifts, when influence of drilling water was at a minimum, see Table 7-13 and Table 7-14, Minimum and maximum depths  are shown The minimum depths  are measured at lhe start of the drilling The first encountered water table in a hole is  not necessarily  the only  or relevant ground water table at the given location for a given prob lem to be analysed for a given structure Permeable zones  further down may  have caused draining of the rock  mass  underneath and when this rock  mass  is  penetrated by  a borehole, a complex  situation may  occur. Water from an upper reservoir may  then be led through the hole to a lower reservoir The actual ground water table may  be expected at what is  shown as  the maximum depth of water table, or somewhat deeper, depending on lhe issue for which the elevation of ground water is  rele vant
In the boreholes  at Baro 1 dam site, depths  to the deepest water table vary  between about 5mm BlD-1 and B1D-4 and about 22 m in B1D-2 Bi D-2 is  located on top of the ndge between the gorge and lhe river val ley. and it is  expected that the ground water level here would be deep. In boreholes  in Baro 1 tunnel area, depths  vary  between about 5 m and about 28 m
At the Baro 2 dam site, depths  to deepest water table vary  from about 8m in B2D-3 to dose to 23 m in B2D-1 The latter borehole passes through a highly  permeable layer at this  depth These reported depths correspond to water levels  about 1315 masl in B2D-1, 1304 masl in B2D-2, 1299.6 masl m B2D-3 and 1305 masl in B2D-4
The   ground   waler   level   may   vary   considerably   over   the   year   depending on rainfall seasons
0fl ro vaiur^e
-1* Stptanitef 2ms doc NORPLAN - NORCONSULT - LAHMEYER JV
m association with Shebelle Engineering and WWDSEFederal   Democratic   Republic   of   Ethiopia   -   Ministry   of   Water   Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Page 7 26
Table 7-13 Baro 1 exploratory boreholes Depths to the water table
Borehole no.
1
Depth to water table, m
1 Minimum (date)   Maximum
(date)
B1D-1
B1D-2
B1D 3
' B1D-4
' B1D 5
j B1D-6
| B1T-1
| B1T-2
| B1T-3
B1T-4
B1T-5
| B1T-6
1 5(11.03 05)
6.9 (30 03 05) 10 8 (04 04 05) 1 5 (05 04 05) 8 6 (10 04 05)
9 6(13 05 05)
3 7(15 03 05) 2 3 (29 03 05)
| 4 9(18 03 05) ' 3 9 (09 03 05)
0 3 (09 03 05) 9 0 (27 03 05)
6 • 2303 05) 22 3 (03 04 05)
17 5(07 04 05) 5 1 (12 04 05) 14 7(14 04 05)
16 6(14 05 05)
9 6(22 03 05)
10 2(02 04 05) | 27 8(23 03 05)
19 4(14 03 05) 4 7(01 04 05)
18 9(29 03 05)
Table 7-14 Baro 2 exploratory boreholes Depths to ground water table
Borehole no.
Ground water dept
Minimum
(date)
1 5(15 04 05)
h, m
Maximum
(date)
B2D-1
B2D-2                                   2 1 (20 04 05)
B2D-3
0 6(19 04 05)
22 6(19 04 05) 16 4(25 04 05)
B 1 (06 05 05)
B2D 4
B2T 1
B2T-2
2 5 (09 05 05)
0 0 (20 05 05)
10 3(11 05 05)
0 5 (27 05 05)
0 0 (29 03 05)                    0 5 (10 04 05)
B21 3
1 B2T-4
B2T-5
1 B2T-6
GJD -1
GJT-1
5 0 (29 05 05)
6 0 (29.05 05)
5 0(15 06 05)
7 4 (18 04 05)
1 2 (16 04 05)
D O (26 04 05)
10.0(01 06 05)
22 5(01 06 05)
10 0(19 06 05)
50 2 (21 04 05)
9 8 (02 05 05)
7 4(30 04 05)
7.5
Test Pits
The logs  of the new test pits  excavated for the feasibility  study  as  well as the test pits  excavated for the pre-feasibility  study  are presented in Annex  4 D The logs  give descriptions  of the soil encountered as  well as the locations  of the samples  taken
1  he  planned  test  pits  on  the  left  bank  both  at  Baro  1  dam  site  could  not be  excavated  because  of  early  inset  of  the  rainy  season  which  made river crossing impossible
Baro Volume 4A - Geology 14 September 2006 doc 
NORPLAN - NORCONSULT - LAHME YER JV association with Shebelle Engineering and VWVDSEFederal Democratic Republic of Ethiopia Ministry of Water Resources
Volume 4
A
Feasibility Study of Bara 1 & 2 Multipurpose P-of eels
Page 7-
27
7.6
Laboratory Results
Rock samples collected from core drillings have been tested m the
labo
ratory for classification and for determination of engineering propert
ies 
Detailed results from the laboratory testing are presented in Annex 
4E
A  summary  of  results  of  testing  on  rock  core  samples  is 
shown  in
Table
7-17. and finally  the results  from petrographic  analyses  are summarised
in Table 7-19 and Table 7-20 Petrographic  analyses  were conducted at
the
Mineralogy 
&
Petr
ography 
Labo
ratory 
of
Ethiop
ian
Geological
Sur
vey.
7.6 1
Rock strength - UCS
Results   from   Uniaxial
compressive
strength   (UCS)
testi
ng
are   inc
luded
in   the   laboratory   report
in   Annex   4
E   Classification
by 
the
Interna
tional
Society for Rock Mechanics (ISRM) classifies UCS strengths as
UCS Or
>250MPa
Strength classification
Extremely high strength (E H)
100-250 MPa
Very high strength
(V.H)
50-100 MPa
Hrgh strength
(H)
15-50 MPa
Medium strength
(M)
5-15 MPa
Low strength
(L)
In Table 7-15 (Baro 1 dam area). Table 7-16 (Baro 1 tunnel area). Table 7-17 (Baro 2 and Genji dam areas) and Table 7-19 (Baro 2 and Genji tunnel areas) is shown the above classification of the UCS strengths
tarovohinw^ Geology 14 Setter20C6doc NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Water Resources F easibility Study ol Baro 1 & 2 Multipurpose Projects
Volume 4 A Page 7-28
Table 7-15 Baro 1 dam site - UCS testing of core samples
UCS
BH NO
hole (m)
5 97
42 6 MJ
| B1D-1
2366
24,0 M
44 36^
19,3 M
I ETD-2
32 8
44 9 M
B1D-3
2344
615 H
23 92
26,6l M
20 60
39.6] M
B1D-4
51 33
23 ij
M
66 16
18 1
M
B1D-5
52.79
39,4
M
12 33
61,6
H
B1D6
14 1C
30.0
M
18 76
71 0
H
28 8€
57 7
13 81
82.4
rh
-
H
B1D-7
27 8C
i        48.8
H
46 8(
>       39,9] H
H=high, M=medium. L=low, VL=very low, see explanation above Table 7-16 Baro 1 tunnels - UCS testing of core samples
Depth in bore-
UCS
BH NO
hole (m)
1
MPa
Classi fication i
B1T-1
4333
65.8
nrl
10.45
32.0
M
1662
137,1
VH
B1T-2
16 72
97.9
H
16 87
58.2
H
45 18
56 9
H
64 23
64 1
H
BIT 3
90 22
43.7
M
113 34
42.3
MI
150 13
1057
VH
16 22
969
H
B1T-4
122 1
45 7
M
16085
47,2
M
36 63
17 0
M
B1T-5
39 30
86 2
H
54 34
45.7
M
76 31
60.8
H
B1T6
22 3
39,7
M
48 31
81.3j H
Baro volume 4A Geology - 14 Septemoe 2006 doc NORPLAN - NORCONSULT - LAHME YER JV
in association with Shebelle Engineering and WWDSEfederal Democratic Republic of Ethiopia - Ministry of Water Resources Feasibility Study of 0aro 1 & 2 Multipurpose Projects
Volume 4 A Page 7-29
Table 7-17 Baro 2 and dam sites - UCS testing of core samples
UCS
BH NO
y- -
Depth in bore hole (m)
MPa
Classi
fication
16 17
90 2
H
B2D-1
30 14
59,0
H
36 31
589
H
02D-2
20 33
63,5
H
360
78 0
020-3
854
55.2
H
34 83
56 3
H
B2D-4
6 75
81 1
H
24 91
544
H
GJD 1
8 93
84 9
H
32 6
52 2
H
8 75
69 0
H
GJD-3
9.09
52 2
H
28 0
51,9
H
Table 7-18 Baro 2 and Genji tunnels - UCS testing of core samples
UCS
BH NO
Depth in bore
hole (m)
MPa
Classi
fication
B2T-1
21 44
34 3
M
36 24
324
M
B2T-2
72 0
64.2
H
97 72
49 0
•-
M
B2T-3
43 2
32 2
M
58 11
68,8
H
88
49 6
M
20 96
8.9
L
24 32
19.4
M
B2T-4
32 4
71
L
98 16
46 7
M
149 45
46 8
M
207 19
106
L
83 95
46 9
MJ
B2T-5
141 24
304
M
181 0
50 9
H
B2T-6
38 73
60 3
H
_                36 34
58,3
H
39.11
60 4
H
GJT-1
42 49
51.8
H
73 46
53,4
H
73 76
386
M
93 64
298
M
Baro volume** -                  - '* Septet ?oo6 aoc NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Waler Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Page 7-30
Figure  7-9  shows  a  compilation  of  the  UCS  values  from  Baro  1  and  Baro 2 / Genji
Of totally  36 samples  from Baro 1. 55% showed UCS classified as  me dium, 39% as  high and 6% as  very  high Of totally  38 samples  from Baro 2, 3% showed UCS classified as low 34% as medium and 58% as high
762
7 6.3
Figure  7-9  Distribution  of  UCS  figures  from  core  samples  in  Baro  1  and Baro 2
Petrographic analyses
The results of petrographic thin section analyses are summarized in Table 7-19 (Baro 1) and Table 7-20 (Baro 2). showing percentages of
minerals and concluded rock types Detailed results are presented in
Annex 4 E
Soil Samples Testing
Soil samples  collected from the test pits  have been tested in soils  labo ratory  Detailed results  are presented in Annex  4 E Summary  of the re sults  of classification tests  as  well as  compaction tests  are presented in Table 7-21 for Baro 1 and in Table 7-22 for Baro 2
The  compaction  tests  show  that  the  clay  material  is  suitable  as  material for constructing clay cores at both dam sites
Shear   strength   parameters   are   within   the   normal   range   for   residual clayey materials
------------------ —-14 September 2006 doc Baro volume
NORPLAN - NORCONSULT - LAHMEYER JV jn association Wlth Shebelle Engineering and WWDSEFederal Demoaalic Republic ol Ethiopia Ministry of
Feasibility Study o< Baro 1 & 2 Multipurpose Projects
Resources
Volume 4 A Page 7-31
Table 7-19 Baro 1 Petrographic thin-section analyses, conducted at the Mineralogy & Petrography Laboratory of Ethiopian Geological Survey.
Borehole nurnbors. Depths In boreholes
Mineral
[
BID-!
1 8.0
I B1D-4
51.5
|   B1D-5 I 39.5
B1D-6
12 5
1 B1D-6
29.3
BlD-7
28.3
B1D-7
■ 46.5
01T-1
43.0
B1T-3
64 6
B1T-3
113.3
B1T-4
122.5
B1T-5
37.0
Plag»octese
19
16
38
26
12
15
23
15
10
10
20
17
Microcline
-
15
-
1b
*
24
5
5
30
Trace
-
-
Orthocase
-
13
■■
10
■
5
17
-
15
-
-
K-teldspar
10
(-
-
I36
-
-
-
-
10
Qjartz
10
20
-
I 11
I 20
24
9
13
13
1?
IB
10
Biotite
.
1 zo
9
-
26
10
15
30
35
12
24
20
20
Muscovite
r-------------------
-
5
13
5
7
Trace
4
8
•
5
-
Senate
12
-
3
-
Trace
1
2
-
■
1
Hornblende
ra
*
-
-
-
10
Trace
-
5
1
13
Pyroxene
-
36
-
-
-
-
-
-
-
-
-
Epidole
10
-
1
5
Trace
3
5
3
15
5
2
Apatite
6
-
Trace
2
Trace
Trace
Trace
2
Trace
Trace
5
Sphene
12
-
5
1
-
10
3
3
10
10
7
Zircon
-
■
Trace
T-aco
•
-
-
Treco
...
-
Trace
Calcite
2
5
Trace
2
Trace
Trace
2
-
Trace
1
?
Chlorite
Trace
Trace
-
2
Trace
-
Trace
1
Trace
1
OliviOH
-
-
9
•
-
-
-
-
-
Zeolite
-
10
-
-
-
ID
-
15
-
-
-
Opaque
3
Trace
12
3
2
5
s
Trace
,1
9
6
10
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3 aro Volumu 4 A - Geology-14 September 7006 doc
NORPLAN - NORCONSULT - LAHMEYER JV in associalion with Shebelte Engineering and WWDSEVolume 4 A Page M2
Mineral
Borehole i
,nol° nvmbers.Depthsin boreholes^mj^^^'^^ 3f
I
16 8
B2T-1            B2T-2
B2T-2
of Efh^pian fioo,o9'ca/ Survey
B2T-6 GJD-1 rGJD3 GJT-1
’ll----- po__ _p~-
25
Microcline
*7
~ T 22
Orthoclase |7
•< feldspar
i Quartz 
! Biotite
| Muscovite
Sericite
Hornblende
Pyroxene
Epidote
Apatite
Sphene
Zircon
Calcite
CMonle
Voican c Qiab%
Opaoue
’race
Trace
Trace
Trace
Trace
W
Truce
Trace
Trace
Trace
2~
Q HJ
E?
58
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'u
2E
|
(/)
ii
u
NORPLAN - NORCONSULT - LAHME^
DS£
JV
Baro Volume a A Geology - September Z006 doc
,n association with Shebelle Engmeenng and VWD^th
Federal   Democratic   Republic   of   Ethiopia   -   Ministry   of   Water   Resources Feasibility Study of Ba ro 1 & 2 Mullipurpose Projects
Vo/ume 4 A
Pago 7-33
J
Table? 7-21: Summary of classification and compaction testa Bare 7
Sieve Analysis
Hydrometer Analysis
Atterberg
Limits
Modified
Proctor
L
. No.
. -J • 4- *'?
Code
ti
%p
asslng
(mm)
Smaller than
Particle size, mm
LL
PL
Placiticity 
index
OMC
%
MDD
g/cc
2
WS
0,425
0,075
0,02
1
0,002
0,001
I
>
2mm%
sand
(%) 2-
0 075
mm
silt(%)
0.075-
0.002
mm
Clay(%)
<0,002
mm
I1
B1-NTP-Q4
1 75-2
100
85
75
67
46
40
-
L 25
29
46
56
32
24
23.5
1.61
|2
B1-NTP-D4
4 -4 25
100
97
94
87
66
61
6
28
65
64
43
21
32.8
1.49
||   3
B1-NTP-D5
2.5-28
100
98
94
79
45
25
6
49
45
60
46
14
4f
B1-NTP-Q1
15
100
67
50
48
25
15
50
25
25
46
17
29
15.0
1,83
5
01-NTP-Q2
2.4
100
57
40
33
20
18
60
20
20
38
26
12
12.1
1.97
6
B1 NTP Q3
3.1
100
80
34
34
8
5
66
26
8
NP
NP
NP
14.3
1,85
7 ..
B1-NTP-Q5.
2.8
100
98
91
1 30
43
35
9
48
43
63
43
20
3.5
1,58
8
B1-NTP-Q5
3.1 -3.4
100
99
99
72
64
60
1
35
64
64
39
25
29,0
1 60
r
9
B1-NTP-CM
2.0
100
88
75
75
60
45
-
25
15
60
54
45
9
22.4
1.72
I
I
Average
28
31
42
49
32
17
17.0
1.52
Bam Voium* 4A Geology- ■ 14 September 2005
NORPLAN - NORCONSULT - LAHMEYER JV in association with Shebelte Engineering and WVVDSE
Depth m,7'
Volume 4 a
Page 7-34
fests Baro 2
Sieve Analysis
% passing (mm)
Smaller than
Hydrometer Analysis
Particle size, mm
Atterberg Limits
Placiticity
index
Modified Proctor
0,425    0.075     0,02     0,002    0,001
>
2mm%
sand
(%) 2-
0.075
silt(%)
0.075-
0.002
OMC
%
MDD
B2-NTP-
Q2R
B2-NTP-
Q2U
B2-NTP-Q3 B2-NTP-Q3 B2-NTP Q4~ B2-NTP-Q4
mm            mm
0 7-10         100
0.7-1 0         100         70 09-1.2
15-18            100
61
.
53         47
.
42
80
78                70
5T
B2-NTP-D1           0  4^  0.7      100
75
55          33
23,6
23J
26.0
28.3
1,75
1.86
1 -8L
L65
1.62
0 3-06 _° 5
43
23          11
B2-NTP-Q5
B2-NTP-Q6
B2-NTP-Q7
100
100
28
8
NP             NP
0
0
0     ?_       100
□ 5 100
20         0
20
B2-NTP-Q2              045            100
0
0
0
0
0
6
o
10
0
0
Baro Volume 4 A - Geology • 14 September 2006 doc
NORPLAN - NORCONSULT - LAHMEYER JV in association with Shobelle Engineenng and WWDSE
1.7\
XFederal Democratic Republic of Ethiopia - Ministry ot Waler Resources Feasibility Study cf Ba<o 1 & 2 Multipurpose Projects
Volume 4 A Page 7 35
7.6 4
Construction materials testing
Rock samples                 Rock samples have been collected from the drilled cores as well as
block  samples  from Baro 2 potential quarry  site for testing for evaluation of suitability  for the use as  concrete aggregates  The samples  were tested on Alkah-Silica Reactivity  (ASR) by  using Ethiopian Messobo OPC Cement.
Alkali Silica Reactivity  The results  of laboratory  testing for ASR indicate that there is  no Alkali Silica Reactivity  for the combination Ethiopian Messobo OPC cement and aggregates from the rocks at Baro see Annex 4 E.
Rock sources                 The rock samples collected from Baro 1 and Baro 2 are from the gneiss
rock  formation. This  rock  is  considered suitable for concrete aggregates Quantities  are sufficient at in both project areas  both for concrete aggre gates as well as for rock fill matenals m the dam
Natural sand                   Natural sand and gravel materials for use as fines in concrete or for filter materials  m  the  dams  are  only  scarcely  identified  in  some  over  courses The   quantities   are   small   and   materials   are   spread   over   large   areas, which  make  it  difficult  to  excavate  with  proper  quality  and  in  sufficient quantities  Therefore,  it  is  recommended   to  use  crushed  rock  materials for concrete as well as for filter matenals.
Wr0V0iun*4A G^xofly-KSeptemcerzooB.doe NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineenng and WWDSEFederal Oemocrabc Republic of Ethiopia - Ministry of Waler Resources Feasibility Study of Baro 1 & 2 Multipurpose Projects
Volume 4 A Page 8-1
8
8.1 8.1 1
Lithology
PROJECT GEOLOGY - BASED ON GEOLOGICAL MAPPING AND SITE INVESTIGATIONS
General geology
Geology of the Baro 1 area
General
See  Geological  map.  Drawing  Ba1-E01,  and  Geological  Section  of  Wa
terway.   Drawing   Ba1-E04   Baro!   Hydropower   Project   area   is   underlain
by  Precambrian crystalline basement rocks  belonging to the Alghe Group (ARI) of the Geological Map of Ethiopia (Mengesha Teferra et al.
1996)   These   Precambnan   crystalline   basement   rocks   are   unconform-
ably  overlain  by  basalt  lava  flows  belonging  to  the  Mekonen  Basalts  of
the  Geological  Map  of  Ethiopia  far  away  from  the  Baro  project  area  A significant   part   of   the   bed   rocks   are   blanketed   by   red   lateritic   soil   Along   ( the  banks  of  Baro  River  and  its  tnbutanes.  alluvial  matenals  are  found  as scattered deposits
Soil formations
Alluvial deposits  sand, silt and clay  assumedly  with a few meters  thick ness. occur along the Baro River and its  tnbutaries  These sediments are deposited during the main rainy  seasons, when these areas  are flooded On the geological map. alluvial deposits  are shown at four separate places  Two of them occur downstream and upstream of the dam axis  and the other two occur Northeast of the powerhouse and at the tailrace outlet along both banks of the Baro River
A  considerable  pan  of  the  area  is  covered  by  residual  soil  derived  from the   underlying   Precambnan   basement   rocks   Along   the   tunnel   align ment.  more  than  90%  of  the  area  is  soil  covered.  The  thickness  of  the soil  may  be  highly  variable  In  the  exploratory  bore  boles  along  the  tun nel  alignment,  the  thickness  of  the  soil  overburden  ranges  from  0  m  in borehole  B1T-4  to  about  8m  in  borehole  B1T-1  In  the  dam  area,  the  soil thickness vanes from 4m in B1D-1 to about 51m in B1D-5
A  detailed  description  of  the  soil  deposits  is  given  in  the  report  from  geo logical mapping, Annex 4 F
Bed rock
On the 1 250 000 Geological Map Gore (Mengesha Teferra et al 1907). see Figure 5-1. the Precambrian bedrock  in the Baro 1 project area is denoted Pgn« —  Hornblende - biotite and amphibole gneisses, granitic gneisses  and migmatites  The geological mapping for the present study (see Annex  4 F) shows  that these are banded gneisses  which are more or less  continuously  exposed along the course of the Baro River. Excel lent exposures  also occur along the Northeastern segment of the tunnel alignment at three separate places  These exposures  form conspicuous ridges in the area
m ’grnatitic. cut by numerous sub-concordant migmatitic material Discordant dykes and pods of
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Foliation
pegmatite and granite are also common The gneisses  are dominantly slightly  weathered, well foliated, medium grained light gray  biolite and gray  to dark  gray  homblende-biotitrte gneisses  Btotitic  and/or horn blende are dominant mafic minerals.
The foliation of the gneisses is with stnke varying from N-S to NE -SW and with dip varying from about 10° to about 45° towards W and NW, see stereonet in Figure 8-1 below
Weathering
Figure   8-   f   Foliation   -   Bare   1   Equal-area   stereonet   (Schmidt   net),   lower
hemisphere
In  Figure  8~1  above  are  foliation  planes  shown  as  large  circles.  Contours on the right side show concentrations of poles to foliation planes
Depth of weathering is variable In lhe exploratory bore holes at Baro 1
dam site, thickness  of pronounced weathenng (highly  or severely weathered material) below whal has  been defined as  soil in Table 7-3 vanes  from 0mm borehole B1D-1 to 6 m in borehole B1D-2 In the boreholes  along lhe tunnel alignment, the thickness  varies  from 0 m in borehole B1T-4 to 8 m in borehole B1T-1 Deeper weathering may  also occur, especially in connection with weakness zones
Fractunng jointing According to definition, joints  in a rock  mass  are discontinuities  with no visible displacement. In this  report, joint is  used as  a scale term and may therefore also include discontinuities wrth minor shear ruptures
Degree of jointing of the rock  mass  seems  to vary  considerably  Varia tion in joint spacing is  not easily  assessed from visual observations  of rock  exposures, due to the scattered occurrence of these and difficult access  A complicating factor is  also that protruding, exposed rock  often is  less  fractured and of a higher quality  than soil covered rock. Rock mass  of inferior quality  tends  to be more susceptible for the geomorpho logic  processes  and to erode faster than rock  mass  of superior quality The result of this  is  that rock  being exposed is  normally  superior in qual ity, compared to rock that is soil covered In exposures at the Baro 1
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dam site variation in joint spacing from a couple of dm to more than 2 m was observed
The variation in degree of jointing is  reflected by  the variation in RQD quality, assessed for core samples  from core drilled holes, see chapter 7.2.3 Figure 7-5 and Figure 7-6 RQD (Rock  Quality  Designation) is  de fined as the percentage of core pieces with lengths of 10 cm or more
RQD-values  are high in boreholes  B1D-1, -2. -6 and -7. intermediate in B1D-3 and -5 and low in B1D-4 In the latter the rock  is  strongly  frac tured and partly  crushed and with RQD values  characterised as  low or very low for more than 90% of the hole within rock
Joint orientations  observed al the Baro 1 dam site are shown 3- dimensionally  in the stereonet in Figure 8-2 and 2-dimensionally  in the rose diagram in Figure 8-3 Dominant joint onenlalion is  with strike close to NNW-SSE Another orientation is  with strike about NW-SE The stereonet and rose diagram from Baro 1 are based on a very  limited number of measurements  (28) and the concluded orientations  may  not be representative
Figure 8-2. Joint orientations - Baro 1 Equal-area stereonet (Schmidt net), lower hemisphere Contours show showing concentrations of poles to joint planes
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Faults, weakness zones
Figure   8-3   Joint   orientations   -   Baro   1   Rose   diagram,   statistical   distribu tion of joint stnke orientations
Tectonic  faults  or weakness  zones  are not visually  observed in exposed rocks  in the Baro 1 area, due to soil cover Topographical lineaments identified by  stereographies! interpretation of aerial photographs  are though in many  cased concluded related to faults  or weakness  zones Such zones  are of special importance in regard to both tunnels  and dams, as  the rock  mass  here is  disturbed or weakened Inferred weak ness  zones  on the Baro 1 geological map are of various  orientations Only  a few inferred faults  have the NNW-SSE orientation found to be dominant for the joint orientation measurements  Possibly  the most prominent direction is  NW-SE to WNW-ESE, a direction also observed in lhe joint orientation measurements  WSW-ENE to SW-NE also seems  to be common direction
An attempt has been made to range the inferred weakness zones in re
gard to width, but this ranging is highly uncertain due to the soil cover
Information about faults  and weakness  zones  may  also be obtained from exploratory  core drillings  As  seen on the geological map. boreholes B1T-1, -2, -4 and -5 are located at, or in the vicinity  of, inferred weak ness  zones. B1T-1. located between 2 inferred prominent weakness zones  are strongly  fractured and brecclated in the upper 20 m of the hole This  does  though not correspond well with the interned weakness zones. B1T-2 is  located very  dose to one of these weakness  zones  but the borehole is  without indication of any  weakness  zone. The same is the case with B1T-4, located at the junction between 2 inferred weak
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1
6.1 2
ness  zones  B1T-5 is  partly  strongly  fractured at depth 40 to 46 m. pos- sibly  corresponding to the inferred weakness  zone close to this  hole O the boreholes  al the dam site. B1D-1 is  located close to an inferred weakness  zone but without indication of this  In B1D-3 there are strongly  fractured or crushed sections  between about depth 36 m and depth of hole at 70 4 m. assumedly  corresponding to the inferred nearby prominent weakness  zone Most disturbed is  the rock  in B1D-4. with strong fracturing and crushing along most of the borehole, but an expla nation for this  is  not easily  found on basis  of the inferred weakness zones in this area
These examples  are given to show the uncertainty  in the interpretation of weakness  zones  in this  mainly  soil covered area, and that such zones may  be found al unexpected locations  In many  cases, the rock  mass along weakness  zones  is  more erodible than the rock  mass  away  from the zones  Weakness  zones  will therefore tend to be located in depres sions  and covered with overburden Visual observations  of weakness zones  will often give a misleading and too positive picture of weakness zones, both in regard to size and to character Impression from study  of available information is  that assessment of weakness  zones  on basis  of aerial photographs  and of geological mapping may  give a too optimistic picture Exploratory  drillings  show weakness  zones  that were not de tected by the two first methods
Geology of the Baro 2 / Genji area
General
See Geological map. Drawing Ba2-E02, and Geological Sections  of Wa terway  Drawings  Ba2-E07 and Gen E02. As  for the Barol area, the Baro 2 area is  underlain by  Precambnan crystalline basement rocks, be longing to the Alghe Group unconformably  overlain by  basalt lava flows belonging to the Mekonen Basalts  A significant part of the bed rocks  are blanketed by  red lateritic  soil Along the Baro River, alluvial materials  are found as scattered deposits
Soil formations
The project area, except for parts  of the Baro river bed and steep sec tions  of the slope up from the nver, is  in general covered by  residual soil. The thickness varies, but general thickness is assumed of a few metres
Low gradient wide valleys  and low lying flat banks  of the Baro River are underlain by  alluvial sand silt and clay  with assumed moderate thick ness
As shown in Table 7-5 and Table 7-6, thickness of soil overburden found in the exploratory drill holes is highly vanable Soil thickness at Baro 2 dam site varies from 2 5 m in B2D-4 to more than 16 m in B2D-2 and at Genji dam site the soil thickness in borehole GJD-1 is about 3 m and in GJD-3 about 5 m For holes along tunnel alignments, the soil thickness varies from less than 5 m (B2T-4) to 11 m (B2T-1). with exception of
B2T-3 with more than 40 m
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Lithology
Bedrock
On the 1 250.000 Geological Map Gore (Mengesha Teferra et al 1987), see Figure 5-1. the bedrock  in the upper part of the Baro 2 headrace tunnel is  denoted Pgnj - Hornblende - biotite and amphibole gneisses, granitic  gneisses  and migmatites  The bedrock  in the central, and mam part, of the tunnel system, with the power house area is  denoted Pgt, - Syn-tectonic  granites  and in the lower part Pgns: - Paragneisses  of various  composition, including hornblende gneiss  and amphibolite. The geological mapping for the present study  has  given a more detailed pic ture of the lithological vanations. but is  generally  consistent with 1.250,000 Geological Map Gore
The bedrock  is  unconformably  overlain by  basalt lava flows  belonging to lhe Mekonen Basalts  (PNmb) of the Geological Map of Ethiopia A younger plagioclase porphyritic  basalt flow (Ba) not shown on the Geo logical Map of Ethiopia, occupying lower elevations  than the Makonen basalts  has  also been identified unconformably  overlying the basement rocks in lhe Baro 2 area
The Precambrian crystalline basement rocks  are in this  study  mapped
as Pcgn!. Pcgn  and Pcgn
3
3
Pcgn,
Pcgn;
Pcgnj
Ba
Foliation
Bara Volume 4A
Pcgn, probably  paragneisses, comprises  intercalated biotite, horn blende-biotite and biotite-quartzofeldspathic  gneisses, locally  migrna- tised and banded They  constitute the major part of the bedrock  in the Baro 2 and Gen;i headrace tunnel area as  well as  tailrace tunnel area and are well exposed along lhe Baro River bed
Pcgn2      comprises    biotite    orlhogneiss    of    granitic    composition    and    plu
tonic   origin   and   are   found   in   dam   area   and   upper   end   of   the   Baro   2
headrace tunnel They are uniform, coarse grained and well foliated
Pcgn3 comprises intermediate to ultramafic plutonic intrusives, such as 
meiadiorite metagabbro, amphibolite and hornblendite, found in the
downstream part of rhe tailrace tunnel The predominant rock is relatively 
uniform strongly foliated, dark gray metadiorite that locally grades into
amphibolite and also contains layers and pods ot metagabro and meta
hornblendite
Sa    comprises    porphyric    basalt    lava    flows    overlying    the    Precambnan gneiss formations
lhese basalt flows  are found above about 1300 m elevation, but are poorly  exposed, being heavily  vegetated and covered by  red lateritic  soil. They  are apparently  separated from the basement rocks  by  paleosoils. The age of this  basalt is  unknown It occurs  al about 300 meters  lower elevation than the Tertiary  Makonen plateau basall flows  and is  pre sumably  younger than this. The rocks  are vesicular, containing coarse plagioclase phenocrysts
As  shown by  the stereonet in Figure 8-4. the foliation in the Baro 2 - Genji area is  highly  stable, with strike around N-S and low to moderate dip lowards w
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Weathering
Fracturing, jointing
Figure 8-4 Foliation ■ Baro 2 and Gen/i Equal-area stereonet (Schmidt net), lower hemisphere
In Figure 8-4 above the foliation planes are shown as large circles Con tours on the right side show concentrations of poles to foliation planes
Degree of weathering is variable and as descnbed in the report from the geological mapping, Annex 4 F, the weathering seems to be more ex tensive for mafic rocks than for rocks of granitic composition.
Weathering thickness at the Baro 2 dam site is highly vanable, from 0 m in boreholes B2D-3 and -4. on the nght side of the river to 21 m in the upper borehole. B2D-1, on the left side of the nver Some sections of basalt in the upper part of B2D-1 are slightly to moderately weathered, but the general rock quality is though poor down to the top of the gneiss at depth 28 m
At the Genji dam site, the highly weathered zone seems to be thin with less than 1 m both in borehole GJD-1 and in GJD-3
For the tunnel boreholes, the thickness  of the weathered zone below what has  been defined as  soil overburden in Table 7-6 is  small with maximum of about 10 m in borehole B2T-1
Degree of jointing of the rock mass seems to vary considerably As de scribed for Baro  1, chapter 811. variation in joint spacing is not easily assessed from visual observations of rock exposures, due to the scat tered  occurrence  of  these  and  difficult  access  The  vanation  in  degree of jointing is reflected by the vanation in RQD quality assessed for core samples from core drilled holes, see chapter 7 2 4, Figure 7-7and Figure 7-8  RQD  (Rock  Quality  Designation)  is  defined  as  the  percentage  of core pieces with lengths of 10 cm or more
RQD-values are especially high in the dam site bore holes B2D-3 and - 4, and in GJD-1 and-3. all with more than 90% of Very High RQD. For
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the   tunnel   bore   holes,   the   portion   of   Very   High   RQD   varies   from   about 60% (B2T-2) to about 80% IB2T-5)
Joint orientations  observed at the Baro 2 and Genji dam sites  are shown 3-dimensionally  in the stereonet in Figure 8-5 and 2-dimensionally  in the rose diagram in Figure 8-6 Dominant joint orientation is  with strike about E-W Another onentation is  with strike about N-S, parallel to the strike of foliation The stereonel and rose diagram from Baro 2 are based on a large population and considered representative
Figure G-5 Joint orientations - Baro 2/Genji. Equal-area stereonet (Schmidt net), lower hemisphere Contours show concentrations of poles to joint planes
Stihl'ical
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Faults.
weakness  zones  Tectonic  faults  or weakness  zones  are nol visually  observed in the Baro 2 area due soil cover Topographical lineaments  identified by  stereo- graphical interpretation of aerial photographs are though in many cases concluded related to faults or weakness zones The inferred weakness zones on the geological map, Drawing Ba2-E02. are all based on inter pretation of aerial photographs and without confirmation by direct obser vation in the field Pronounced onentations are both E-W and N-S in agreement with the joint orientations shown in Figure 8-5 and Figure 8-6
An attempt has been made to range the inferred weakness zones on the geological map in regard to width, but this ranging is highly uncertain due to the soil cover
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9                           ROCK ENGINEERING PREDICTION - GENERAL
9.1
9.2
General consideration regarding excavation methodology
From a rock  technical point of view it is  concluded that the Pre cambrian rock  mass  is  suitable for excavation by  use of traditional drill and blast method Full-face boring (TBM) is  technically  also a possibility, but is  not recommended due to expected high mobilization costs  in relation to tunnel lengths  A variety  of cross-sectional areas would also necessitate different TBM diameters  Further, the tradi tional drill and blast method is  more flexible if change in layout should be desirable due to encountered ground conditions
The tunnel layout presented in this  study  is  reflecting excavation by use of drill and blast methodology  With the actual tunnel sizes  wheel bound tunnelling equipment is  expected most favourable Tunnels  are in general planned to have a D - shape
Shafts  are planned to be circular and optimal shaft excavation meth odology  depends  on factors  as  cross-sectional area and length, but also on the contractors  preference Most likely, the vertical shafts  will be excavated by  use of raise boring and widening by  drill and blast technology
Tunnelling properties
Tunnelling properties encompass the mechanical and geological
properties   of   the   rock   mass   that   are   relevant   for   the   excavation These are
•     strength and strength anisotropy of the rock
•     content and form of abrasive materials
•     frequency, orientation and character of discontinuities
•     stress situation
Summary  results  of strength tesLing are shown in Figure 7-9, both for Baro 1 and Baro 2 The lest specimens  have been selected with lhe intent of covering the variations  in properties  in the project areas Uniaxial compressive strengths, described tn chapter 7.6.1. are highly vanable Of totally  36 samples  from Baro 1. 55% showed UCS classi fied as  medium, 39% as  high and 6% as  very  high Of totally  38 sam ples  from Baro 2 / Genji 3% showed UCS classified as  low, 34% as medium and 58% as high
Mineralogical composition of rock  samples  is  shown in Table 7-19 (Baro 1) and Table 7-20 (Baro2 / Genji). The mineral of importance for abrasion of dnll bits  in the rocks  of concern is  quartz. The quartz content vanes  m general from about 10 to about 25%, which can be classified as low to moderate
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9.3
Special   drilling   rate   tests   or   blastability   tests   have   not   been   con ducted   Drilling   rates   and   blastability   are   expected   to   be   within   t   e normal  range  in  the  major  part  of  the  rocks  Good  tunnelling  progress will   depend   on   satisfactory   blast   design   and   right   choice   of   explo sives   machinery   as   well   as   excavation   and   mucking   methodology   An advance  m  the  order  of  35  m  per  week  for  the  mam  tunnels  is  consid ered likely possibly more
Rock stress conditions and influence on tunnels
Rock  stresses  have not been measured for this  feasibility  study  As- sumedly, the tectonic  history  of the region has  been shifting, with pe riods  of both compressional (reverse faults) and tensional (normal faults) stress  regimes  The remaining influence of the tectonic  history is uncertain, also the present rock stress conditions
Rock  stress  considerations  of importance for the technical feasibility and for design have been included m this  study  The virgin state of rock  stress  in the rock  mass  has  an influence on the tunnelling condi tions  and on the functioning of the tunnels  as  pressurised water con duits  Isotropic  rock  stresses, ie confinement improve the stability and reduce the need for rock  support for openings  in a jointed rock mass  Too high stresses, and especially  high anisotropic  stresses, have a detrimental effect on tunnelling conditions  In hard, brittle rocks  failures  may  occur as  stress  slabbing and spalling, in weak, plastic  rocks  as  squeezing With the moderate vanations  in terrain levels  in and near to the project area stress  slabbing in competent sections  of the rock  mass  is  not expected Squeezing in weakness zones  with plastic  materials  may  occur if the tunnel is  not sufficiently supported Even with the limited information on magnitudes  and ori entation of rock  stresses, it is  expected that rock  stresses  will not be of major importance for tunnel construction, as  the rock  stress  situa tion is not of pnmary significance for the total construction costs
The virgin state ol the rock  stress  is  made up of 3 components: grav ity  tectonic  and residual stresses. For practical purposes, the tec tonic  and residual stresses  may  be regarded as  one effect supenm- posed on the gravity  stresses  With the vicinity  to the East African Rift System, which is  a tensional stress  regime, the rock  stresses  may  be quite unpredictable Rifting due to tensional stresses  is  part of the tectonic  history  and low horizontal stresses  may  also be the case to day  The Headrace tunnels  / shafts  are planned to be unlined, both at Baro 1 and Baro 2 / Genji For unlined pressure tunnels, the require ment for a stable situation is  a minimum principal stress  higher than the water pressure For the tentative layout, including location of powerhouse complex, a rough analysis  of rock  stresses  has  been done, with use of design cnteria based on experience from previous projects, see Chapter 9 9
Exact information on rocks  stresses  is  mandatory  for the detailed lo cation ol the powerhouse caverns  and transition between the unlined Headrace tunnels  and steel penstocks  For this, rock  stress  meas urements will have to be included at the Detail Design Stage.
*4
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4
94
9.5
Stability conditions / design considerations
Stability  conditions  define the need for rock  support, and thereby tunnel costs  as  well as  tunnelling progress  The stability  conditions may  also affect choice of tunnel alignment and tunnel shape Stability of rock excavations depends mainly on:
•     Rock mass quality
•     Rock stresses
•     Ground water
•     Size, geometry and orientation of the excavation
The Pre cambrian basement rocks  are suitable for tunnel construc tion The rock  mass  is  of sufficient quality  and strength for being self- supporting in tunnels  and other underground openings  Weakness zones  will affect the rock  stability  and rock  support needs  and pres ence of such zones  have been considered for Feasibility  study  opti misation of layout and design
Rock failure modes, needs for rock support / rock strengthening Joint  frequency  is  expected  in  general  moderate  to  low  outside  the fault  zones,  creating  block  stability  problems  where  conditions  are  un favourable   Unfavourable   conditions   are   characterized   by   a   joint   set oriented  sub-parallel  to  the  tunnel,  and  a  dip  direction  into  the  tunnel. In  general,  potential  failures  in  the  Baro  tunnels  and  caverns  are  ex pected  to  be  block  failures,  where  rock  blocks  in  roof  and  walls  may loosen  and  fall  out  if  not  supported  Normally,  stable  conditions  are achieved  by  use  of  rock  bolting,  as  spot  bolting  or  as  systematic  bolt ing   in   combination   with   sprayed   concrete   discontinuous   or   continu ous
01 c
.
Figure 9-1 Applications of rock bolting
n  igure  9-1  Left  local  bolts  are  installed  individually  to  anchor  sin ge.  unstable  rock  blocs  In  Figure  9-1  Right:  Rock  bolts  are  installed m a systematic pattern as a more general support in unstable areas
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Figure 9-2 Application of sprayed concrete
Figure 9*2 left For stabilising unstable, small rock  blocks  (moderately to highly  fractured rock, foliated rock  with poor friction conditions, rock pione to spalling, etc  ) Thickness  is  normally  5-B err In Figure 9-2 Right Combination of sprayed concrete and rock  bolts. With thick layer (15-20 cm) this is an alternative to cast concrete lining
The rock  mass  in a fault zone may  not be fully  self-supporting De* pending on fault characteristics  as  strength, stress  situation, occur rence of water and of course width and orientation with respect to the tunnel, various  types  of rock  support is  foreseen This  can be either heavy, reinforced sprayed concrete, if necessary  in combination with spiling bolts  and reinforcement arches, or it can be cast concrete lin ing Minor laults  with inactive, fine materials  may  be supported by  fi bre-reinforced sprayed concrete in combination with grouted rock bolls  Small faults  of this  type may  in some cases  be self-supporting in dry  tunnels, but may  need sprayed concrete as  erosion protection in a water-tunnel In fault zones  and zones  containing materials  with swelling properties, rock  support with higher support capacity  will have to be used In cases  of fault zones  with altered, clayey  material, this  material may  be so weak  that it is  prone to squeezing In such cases  a structural rock  support may  be needed, e g steel-re info reed sprayed concrete ribs  (Figure 9-3) or cast-in-place concrete lining (Figure 9-4)
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xrX.sixIX•
|XIXI*IXIX»XIXIS1%
- rock bolts
\ IS IX IX
x
,vrXixi
i      %ix»xixIx
1. layer of shotcreh (100- 150 mm)
2. and 3. layer of shotcrete
Figure 9-3 Typical design of sprayed concrete ribs
Figure 9-4 Cast-m-place concrete lining
Need for spiling bolts is foreseen with application as shown in Figure
BjfO Volume 4A Geology -14 September 2006 doc NORPLAN - NORCONSULT - LAHMEYER JV
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Volume 4 A Page B-6
9.6
Figure 9 5 Application of spiling bolts.
Rock mass classification
For assessment of rock support needs in a tunnel project a normal procedure is to define the variation in quality of the rock mass Such classification of rock mass quality is then related to the stability condi tions  in  regard  to tunnelling One commonly used  classification sys tem is the NGI-Q system In this, the physical properties of the rock mass, the ground water behaviour and the rock stress situation are input parameters used for establishing the rock mass quality
Realistic conclusions in regard to rock support prediction are depend ing on reliable input parameters for the rock-mass classification Reli able input parameters  are again depending on observations  or test results  of sufficient quantity  and quality  In the case of both Baro 1 and Baro 2 I Genji tunnels, the bedrock  in the tunnel areas  is to a large degree covered with soil deposits, preventing direct observation of rock mass quality Also the dense vegetation is hindering access to the few available rock  exposures  A complicating factor is  also that protruding, exposed rock often is of a higher quality than soil covered rock, e g in depressions  Rock  mass  of mfenor quality  tends  to be worn down by  geomorphological processes  faster than rock  mass  of superior quality  The result of this  is  that rock  being exposed is  nor mally  supenor in quality, compared to rock  that is  soil covered Ex ceptions  occur but in general rock  mass  classification in soil-covered areas  is  considered unreliable Numerous  examples  from tunnelling projects show that rock mass quality judged from rock exposures is
14 September 2006 doc NORPLAN -“NORCO N SULT “UkHMEYER JV in association with Shebelle Engineenng and WWDSEFederal Democratic Rupubhcof Ethiopia - Ministry of Water Resources Feasibility Study of BafO 1 & 2 Multipurpose Projects
Volume 4 A Page £^7
9.7
Water tunnels
Shafts
higher than what is  judged from exploratory  drillings, or higher than whal is  encountered in the tunnel This  problem may  be solved by sufficient information from exploratory drillings
Even with the considerable amount of drillings  done for this  project, information about variation in the rock  mass  quality  is  limited The available rock  exposures  and the exploratory  core drillings  give though some ideas  about variation in rock  quality  and have been used as  basis  for a highly  tentative assessment of rock  support needs.
Rock support philosophy
Rock  support is  provided to improve the stability  tn an underground opening A main principle is  to design the rock  support in accordance with the actual ground conditions  encountered tn the tunnel This  re quires  flexible support methods, which can be quickly  adjusted to meet the continuously  changing quality  of the rock  masses. Such flexibility  is  achieved by  the use of rock  bolls, sprayed concrete, and cast-m-place concrete lining, either alone or as  integral elements  of the support.
Rock supporting works are normally earned out in two main stages:
•       initial  support,  which  is  installed  to  secure  safe  working  condi tions  for  the  tunnelling  crew.  The  types  and  methods  of  support to   be   used   are   decided   in   agreement   between   the   engineer and   the   contractor   The   contractor   is   responsible   for   the   initial support   in   practice   the   working   crew   decides   lhe   amount   of rock   support   necessary   for   their   own   safety   The   initial   support should   be   designed   to   constitute   a   part   of   the   permanent   rock support
•     Additional, or final support, is installed to meet the require
ments for a satisfactory function of the project during its life
The owner determines the additional rock support Usually, he
and his consultant decide both lhe melhods and amounts of
support after excavation.
For water tunnels, special concerns  may  influence the rock  support design One consideration is  the sue (cross-sectional area) of the tunnel in relation to the design discharge and consequences  of reduc tion in size of tunnel opening due to block  falls  Normally, a certain amount of block  falls  can be accepted Another consideration is  the risk  for unacceptable failures  in water tunnels  where future access and repair works  are complicated In such cases, the concluded rock support should be on lhe conservative side
During excavation of a shaft, even small rock falls are a severe nsk tor the shaft crew, and unacceptable Sprayed concrete lining in the
u length of the shaft, installed continuously wrth the excavation will counteract this risk.
Access / cable
aam Volume 4A - Geolog, 14 Sewemt*, 2006 doc NORPLAN - NORCONSULT - LAHMEYER JV
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tunnels
Power station cavern
9.8
In access tunnels and other underground areas where people s ay and work during the operation of the plant, rock falls are unaccep - able due to risk for injuries In cable tunnels rock falls are unaccept able due to the risk for damage on cables / installations. This risk is counteracted by lining the roof of such tunnels in their full length with sprayed concrete
Any rock fall in power station caverns and in transformer caverns is unacceptable, due to risk for personal injuries and for technical dam age Normally both the cavern roof and the walls above the machine hall floor are supported by a combination of sprayed concrete and systematic rock bolting A special concern in large caverns is that ex cavation is done in stages and that rock support in the walls in one stage has to be done before excavation of the stage below This is important in view of access possibilities Another aspect is that the amount of rock support installed has to be sufficient to take care of any potential change in stability condition encountered in the bench below A conclusion of this is that rock support quantities in the roof and walls in the power station caverns normally should be conserva tive
Tentative prediction of rock support needs
As a highly tentative exercise, definition of rock support classes have been done see Table 9-1 In spite of the lack of basis for establishing the variation in rock quality along the tunnels both in Baro 1 and in Baro 2 / Genji, a tentative classification has been done for the pur pose  of  establishing  necessary  design  parameters  and  for  assess ment of rock support costs This classification is considered to be on the conservative side
An evaluation of rock support needs for vanous tunnel dimensions is presented in Table 9-1 By combining the information in this table with the tentative classification of rock mass quality in Table 9-2 (Baro 1) and in Table 9-3 (Baro 2 / Genji). a tentative prediction of rock sup port quantities for the various tunnels is obtained. One complicating factor concerning rock support assessment is that rock support quan tities are not only depending on the quality of the rock mass but also on ideas and habits of the contractor These may be highly variable and influence the actual rock support quantities
Baro Volume 4A Geology ■ f4 September 2006 doc                      NOR PLAN - NORCONSULT^ LAHMEYER JV m association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Feasibility Study ol Baro 1 & 2 Multipurpose Protects
Waler Resources
Volume 1
Page 9-9
r_-
Table 9-1. Rock quality classes, rock support needs tn tunnels (D) and shafts (O)‘
l ^Rock quality
class
NGIQ
^alue
Rock support needs, tunnel or
shaft
Rock support quantities, average / 10m tunnel
15m7-D
44m1-D
55mJ - D
90m7 - D
3B.5m7-O
57m3 - □
Q1 - Very good la extremely good
>40
Scaling, widely spaced spot rock bolts (RB) In tun
nels
2 nos. RB
3 nos RS
5 nos. RB
3 DOS, RB
Soos RB
8 nos RB
Q2 - Good
10-40
Scaling, boiling in tunnels,. occasional sprayed concrete
(SC).
5 nos RB
0.7mJSC
10 nos. RB
1.25 m3 SC
12 nos RB
1.63 mJ SC
15 nos RB
2 m5 sc
12 nos RB
1,7 m3 SC
15 nos. RB 2.1 m SC
a
Q3 - Poor Io fair
1-10
Partly systematic boring m tunnels, sprayed concrete.
5cm.
12 nos RB
6 m’ SC
25 nos RB
12.5 m4 SC
30 nos RB 16.25 mJ SC
35 nos. RB 20 n? SC
30 nos RB
17 mJ SC
35 nos RB
21 m3 SC
Q4 - Very poor
0.1-1
I
1
Systematic bolting in tunnels, sprayed concrete, 10cm. concrete lining
(C1J
20 nos RB 12 nr? SC
10% CL
40 nos. RB 25 m3 SC
10% CL
50 nos. RB 32 5 m3 SC
10% CL
60 nos RB
40 mJ SC
10% CL
50 nos RB
34 m1 SC
10% CL
60 nos. RB 42 m3 SC 10% CL
_
Q5 - Extremely to
i exceptionally poor 1
1
1
L __________________
0.00 b
0.1
L
Short, blasting rounds, spiling bolls, sprayed con crete as initial sup port before con crete lining i$
placed.
12 m" SC
15 nos spiling
bolts
50% CL
25 m'SC
30 nos. spillnq
bolts
50% CL
33 m7 SC
40 nos. spiling
bolts
50% CL
40 m SC
43 nos spiling
bolts
50% CL
34 m SC
48 nos spiling
bolts
50% CL
42rr?SC
48 nos Spiling bolls
50% CL
The table is based on the NGtiQ classification system, presented in ‘Engineenng Geology and Rock Engineering ', Handbook No. 2, Norwegian Group for ffock Mechanics. Oslo. 2000. Some modifications have been done for adaptation to the tunnel sizes of the project.
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Volume 4 A Page 9-12
pia  Confirmation  of  sufficient  rock  stresses  by  stress  measurem the detailed design phase is therefore mandatory
Design of concrete plug, distance fromj>ower station
The chosen design is  based on the philosophy  that with grout curtains  shall act as  a seal between the tunnel and the drained tunnel system downstream
the  concrete  plug unlmed headrace
I
The location of the plug as well as the design of plug and grout curtains has to be chosen so that the amount of water passing this seal is below an acceptable limit. Water passing this seal and leaking into the dry tun nels is to be taken care of by suitable drainage systems
In the design of the concrete plugs, the following has been considered
•  The  plugs  should  be  long  enough  to  keep  the  hydraulic  gradient along  the  plugs  sufficiently  low  Earlier  practice  in  Norway,  with comparable ground conditions is to let the length of the plug be at least  4%  of  the  head  (a  hydraulic  gradient  of  maximum  25)  In some  recent  projects,  shorter  plug  lengths  have  also  been  suc cessful  The  15  m  long  plug  m  the  Access  tunnel  to  rock  trap  in Baro 1 corresponds to about 15% of the water head, and 25 m in Baro 2 5% of the water head
•  The  next  question  is  the  distance  from  the  transition  to  power  sta tion  This  distance  should  be  sufficient  to  give  an  acceptable  low hydraulic  gradient  along  possible  leakage  routes  from  the  unlmed headrace  tunnel  and  into  the  power  station  cavern  and  will  have to  reflect  local  geological  conditions  With  the  chosen  design,  the hydraulic gradient for Baro 1 is about 1 3 and for Baro 2 about 5 0. both considered conservative
9.10                              Groundwater control in underground openings
Most of the underground openings  will be excavated below the phreatic level These openings  will act as  drains  on the groundwater reservoir The groundwater reservoir is  made up of interconnected volumes  of joints  in the fresh rock  and porous  and permeable formations  in the weathered rock  and the soil near and at the surface The porosily  and the conductivity  of the Precambrian gneiss  formation are expected to be in general low. normally  not of any  practical significance In these rocks, water leakage is  expected in connection with faults, and may  be detri mental to stability and may result in reduced production
Groundwater control measures  are needed when a free flow has  practi cal and economic  consequences  Practical consequences  may  be large flows  in drainage ditches  difficult transport road maintenance, difficult conditions  for grouting of rock  bolts  and for spraying of concrete and di rect influence on tunnel stability  through pressure and erosion Pumping costs  both during construction and during operation, may  also warrant groundwater control measures.
Wate control can be achieved through grouting of a tunnel, normally in
r
f ont of the face Low cost cement grout
r
is expected sufficient for the ba-
src grouting Fast setting cement grouts or chemical grouts may however
Boro Volume 4A Geology -14 September 2006doc NORPLAN - NORCONSULT - LAHMEYER JV
m association with Shebelle Engineering and WWDSEFederal Democratic Republic of Ethiopia - Ministry of Water Resources Feas bilily Study of Baro 1 & 2 Multipurpose Projects
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be   required   when   conditions   render   the   use   of   standard   cement   grout unfeasible.
In the powerhouse caverns  leakage water may  be taken care of by  false ceiling, gutters  and gutter pipes  leading to the tailrace tunnel. Even if drainage is  simple to arrange in a powerhouse cavern dry  conditions are preferred Abundant leakage water results  in high humidity  and in creased problems  with oxidation Drilling of drainage holes  or grouting will therefore be initiated, as  required based on observations  during construction The groundwater in case of the powerhouse complex  is both the natural groundwater and whatever contributed by  the pressure tunnel during operaton.
Contact grouting fan grouting and if necessary  drainage holes  will be necessary  around the concrete plug at the transition from unlined tunnel to steel penstock  This  will limit the effects  of the pressure tunnel on ex isting ground water regime around the power station If large flows  are encountered in the tunnels, the leakage is  stopped by  grouting or left to dram according to technical or economic factors as mentioned above
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Volume 4 A Page 10-1
10
10.1
10.1.1 Topography
Ground conditions
10 1.2
GROUND ENGINEERING PREDICTION - BARO 1
Dam
General
The topography of the dam site is characterised by a narrow V-shaped gorge to the left side of the river, and a much wider valley at the present course of the river A ridge rising up to dam crest level separates  the gorge and the present river valley
The soil cover overlying competent rock at both sides and in the middle of the left narrow gorge is shallow whereas the soil cover on both the sides of the river in the mam valley is partly deep, up to 50 m at the up per part of lhe right dam abutment Figure 10-1 below presents a profile along the dam axis showing the topography as well as the soil condition The deep soil cover at the right abutment is to be noted The profile is also shown on enclosed Drawing Ba1-E03
The  combination  of  topography  and  ground  conditions  is  favourable  for splitting the dam in two different sections.
•     A concrete spillway dam structure located in the narrow gorge at the left side of the river, founded on competent bedrock
•      A  main  dam  across  the  present  river  valley  Because  of  the  large depth to bedrock at the upper end of right abutment, the dam has to be  founded  in  firm  residual  soil  In  the  riverbed  as  well  as  the  left abutment, the dam will be founded on rock
Dam options
Various dam types have been considered for the main dam
• Option 1 CFRD Concrete Faced Rock fill Dam
• Option 2 CCRD         Clay Core Rock fill Dam
Option 3 ACRD Asphalt Core Rock fill Dam
All the above options  have an overflow spillway in the side-valley on the left abutment and a diversion tunnel also in the left abutment The in take structure is integrated in the overflow spillway section
Baro Volume 4A Geotogv •
?4 September 2006 doc               NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSEQr
.■A
Z -■!
-I■■
.JI‘
;■• i.W
■- I I-* -.
3 <;
► ■_ .’■• r-J 7Ti K-J
.« 3d
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Figure 10-1 Geological profile in Bare 1 Dam arris.
Haro Volume 4A - Geotpgy - 14 Seolemtwr 2006 doc
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10 1 3
Even if the RCC-altemative is  considered not feasible for lhe total length of the dam site, a combined choice of RCC-dam in the centre towards the left abutment where the overburden is  small, and an embankment to the nght including two saddle dams, may  be a feasible fourth option. This  option could be arranged having the diversion through the lower part of the RCC-dam and of course included the spillway, either in the central valley  section or at the left side valley  The intake could be placed in the RCC-section on the left abutment The drawback  of this option is  the very  high contact/transition structure (H = 75 •  80 m) be tween RCC and embankment
Design  parameters  for  embankment  dam  design Preliminary hydrology results/reservoir levels
• FSL
1520 00 masl
•     Design flood (Q1000)
1522 57
•     PMF
1524,48
■    Assumed significant wave height
1,25 m
■    Assumed rip-rap block dim (CCRD/ACRD) > 0.25 m3
■ Assumed wave run-up (CFRD):                                    2 5m Seismic loads (from Prefeasibility study)
■ Design earthquake                 0 05 g (1/500 years)
•     1/5000
01g
10 1 4
Baro Volume 4A
No  restnctions  on  choice  of  dam  types  are  foreseen  due  to  seismic  load ing
Available materials
•     Residual soil Highly/completely weathered gneiss
From  excavation  of  dam  beneath  core.  Approx  80  -  100  000 m3
o  The  rest  of  the  needed  volume  from  reservoir  area  >  2  500 000 m3
•     Filter matenals
o Crushed rock material and tunnel spoil
•     Quarry
° Approx  4 km to the north Gneiss  good quality. Possible Quarry  sites  in lhe vicinity  of dam (upstream of spillway  sec tion) Including processed rock fill for filter and transition
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zones   in   ihe  different  options,   the  total  quarried  rock  volume would be in the order of 4.5 ■ 7 mill m’.
• Tunnel spoil'
a Headrace + diversion tunnel L=2 8 km, A = 50 nv. Bulking factor 1 4
o Volume Approx 185 000 m’
o Used as transition zones m dam.
Foundation treatment & excavation
Table 10-1: Excavation and grouting depths - dependent on dam type
Dam type
CFRD or ACRO2*
CCRD3*
RCC
Excavation Depth 0
Plinth:
1) To slightly weathered rock
Or
2) 2/3 of water pressure (HJ
□n original ground surface at that point.
Or
3)  Minimum  depth  in  weath ered rock 8 m
Plinth width: Minimum 4 0m on slightly weathered rock 4,0  m  +  H^/20  on  poorer rock qualities
Clay core:
1) To slightly weathered rock
Or
2) 7? of H* on ground suf-
face at that point
Or.
3) Minimum depth in weath- ered rock 4 m
Supporting   shells   on   moder ately weathered rock or firm ground or same level as
core
RCC on slightly 
weathered rock
Grouting
Supporting shells on moder ately weathered rock, firm’’ ground or same depth as 
plinth
1/3 - 2/3 of Hw or minimum 8
m
1/3  -  2/3  of  H.  or minimum 8 m
1/3 - 2/3 of H„ or minimum 8 m
the embankment height al trial point
See   example   below   Upstream   and   downs)   ream   berms   (supporting   fill)   must   be   provided   it   supporting   shells   are not    placed    do     m      or^    7**3      re^    l0ch      By    firm-    it    is    meant    material    with    sukiaen!    bearing    capacity    compared    to
a
u
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10 1 3
Even  if  the  RCC-allernative  is  considered  nol  feasible  for  the  total  length of  the  dam  site,  a  combined  choice  of  RCC-dam  in  the  centre  towards the  left  abutment  where  the  overburden  is  small,  and  an  embankment  to the  right,  including  two  saddle  dams,  may  be  a  feasible  fourth  option This  option  could  be  arranged  having  the  diversion  through  the  lower part  of  the  RCC-dam  and  of  course  included  the  spillway,  either  in  the central   valley   section   or   at   the   left   side   valley   The   intake   could   be placed  in  the  RCC-section  on  the  left  abutment  The  drawback  of  this option  is  the  very  high  contact/transition  structure  (H  =  75  •  80  m)  be tween RCC and embankment
Design  parameters  lor  embankment  dam  design Preliminary hydrology results/reservoir levels
• FSL
1520.00 masl
■ Design flood (Q1000)
1522 57
• PMF
1524.48
• Assumed significant wave height
1 25 m
• Assumed rip-rap block dim (CCRD/ACRD): > 0 25 m3
■ Assumed wave run-up (CFRD) Seismic loads (from Prefeasibility study)
•     Design earthquake 0 05 g (1/500 years)
25m
•     1/5000
01 g
10 1 4
Raro Volume 4 A
No restnctions on choice of dam types are foreseen due to seismic load ing
Available materials
•     Residual soil Highly/completely weathered gneiss
From excavation of dam beneath core Approx 80 - 100 000 m1
o The rest of the needed volume from reservoir area > 2 500
000 m’
•     Filter matenals:
c Crushed rock matenal and tunnel spoil
•     Quarry
Approx  4 km to the north: Gneiss, good quality  Possible quarry sites in the vicinity of dam (upstream of spillway sec tion) Including processed rock fill for filter and transition
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2
10.1 5
zones in the different options the total quarned rock volume would be m the order of 4 5 - 7 mill m’.
• Tunnel spoil
o Headrace + diversion tunnel L=2 8 km. A = 50 m  Bulking factor 1 4
o Volume Approx 185 000mJ
o Used as transition zones in dam
Foundation treatment & excavation
Table 10-1 Excavation and grouting depths - dependent on dam type
Dam type
CFRDor ACRD’1
ccrd”
RCC
Excavation
Plinth:
Clay core
RCC on slightly 
weathered rock
Depth "
1) To slightly weathered rock
1) To slightly weathered rock
Or
Or
2) 2/3 of water pressure (H )
w
2) Vi of H* on ground sur
on original ground surface at
face at that point
that point
Or
Or
3) Minimum depth m weath
3) Minimum depth in weath
ered rock 4 m
ered rock 8 m
Supporting shells on moder
Plinth  width  Minimum  4.0  m
ately weathered rock or firm
on slightly weathered rock
ground or same level as 
4 0 m ♦ HJ20 on poorer
core
rock qualities
Supporting shells on moder ately weathered rock, firm ' ground or same depth as plinth
1/3 - 2/3 of Hw  or minimum 8 m
3
Grouting
1/3 • 2/3 of Hw  or minimum 8 m
1/3  -2/3  of  Hwor minimum 8 m
not placed on moderately weathered rock ' Bv “firm* « lhe errbankment he^hl af that point
<“^"20r fi*">r ™s’*
S meant ma'enal wrth Suf,,aenl beaming capaoty compared to
•                ■rf ■ —WWVi
sheUs are
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Excavation-example 1
Ground surface:           Elevation 1475
Volume 4 A Page 10 5
Water  pressure,  H„  =  1520  -  1475  =  45  m  Dam  height  50  m  *  excava lion
Depth to
•     Slightly weathered rock 
•  Moderately weathered rock 
50 m
25 m
•     ’Firm ground” is defined at depth of 20 m for dams < 50 m
Excavation-example 2
Same ground conditions as above, but ground elevation at 1500. i e wa ter pressure is 20 m and dam heighl 25 m ♦ excavation
Table 10-2 Example 1 &2 Excavation and grouting depths  - dependent
on dam type
Dam type
CFRD or ACRD
CCRD
RCC
Excavation depth
Ex 1:                                                Ex 1
Plinth 30 m depth
Width 4 + 2 25 = 6 25m
Clay core: 22 5 m depth
Ex 1 &2
50 m
Supporting fill 20 m depth                 Supporting fill: 20 m depth
Ex.2
Ex 2
Plinth 13 3 m and width 5 m         Clay core 10 m depth Width 4 + 1 = 5 m
Supp.fill. 13 3 m
Supp fill 10 m
Grouting Ex. 1: 15 - 30 m
Ex 2 8 - 13 3 m
_____
Ex 1 15-30m
Ex 2 8 - 13 3 m
Ex 1. 15-30 m
Ex 2 8- 13 3 m
10 1.6
Dam options considerations
The relative consideration of the pro- and con- for the different dam types  may  be assessed. For optimization the parameters  considered for the different dam types are the costs and safety related to
. Foundation treatment and safety of seepage losses
•     Available materials
•     Flood consideration dunng construction
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•     Flood consideration during service time
•     Work progress schedule and reservoir Filing
•     Maintenance costs during service lime
■ Bottom oullet/sedimentation arrangement
. Overall costs (dam spillway and diversion arrangement)
In Table 10-3 lhe different aspects are given as marks on a scale of 1 to 5.
1. Foor
2    Average
3    Fair
4    Good
5. Very good
Table 10-3 Assessment of alternative dam types
Dam type
Clay
core
CFRD
Asphalt
core
During con struction
Foundation
5
4
4
Available materials
4
5
4
Floods during construction
3
4
4
Work progress
2
4
5
During ser vice time
Floods during service time
3
4
4
Maintenance costs
4
4
4
Sedimentation arrangement
4
4
4
Possibility of leak/int erosion
3
4
4
Average points
3.5
4.1
4.1
Total cost range (%)
100
105
115
Comments to the marks given in Table 10-3 are as follows;
1  Foundation treatment and safety of seepage losses
The higher mark for the clay core option is due to the longer seepage istance from the reservoir to the drained downstream shell The over-
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burden   material   beneath   the   upstream   shell   will   minimize   the
seepage through any potential weaknesses through the grou i g
2    Available materials
The poorer marks for the asphalt core option are the somewhat higher
vulnerability of the delivery of bitumen For the other dam op ions a
matenals needed are available at the dam site, except the cementi ious
matenals which is considered to be readily available The clay as a core
matenal will be plastic giving higher vertical settlements, compared to
the other two embankment options
3    Flood consideration dunng construction
Assuming that a flood greater than the design flood dunng construction will cause an overtopping and hence stoppage and/or damage to the dam, the dams  damages  to the different optional dam designs  will be dif ferent Only  minor damages  can be expected on the rockfill dams  with upstream deck  or asphalt concrete core The clay  core dam will probably have erosional damages  that will cause a longer time to clean up or to reconstruct
4    Work progress schedule and reservoir filling
The dam options  with centrally  placed cores  will allow the filling of the reservoir continuously  during the construction with an allowable reser voir elevation of 2 to 5 m below lhe lowest point of construction A lower mark  is  given to the clay  core option due to a lower construction speed during the rainy  season It may  result in an additional season of con struction.
5. Flood consideration dunng service lime
The  flood  arrangements  are  equal  The  clay  core  option  is  more  vulner able of floods higher the anticipated design levels
6 Maintenance costs during service time and sediment arrangements
7. As for 6
These parameters are assessed equal
8 Possibility of leakage and internal erosion
Assessing the possibility  of an internal erosion in the foundation, has been assessed under point 1 However, lhe options  with asphalt and concrete are not as vulnerable as the clay
Cone/us/on - Recommended dam type
The lower pnce for the dam body using a centrally placed core of clay is su icient to compensate for the fact that the construction time for this 
™ h Wlh 66 °P lhe CntlCal path for tbe P  J ct The CFRD has only 
ro  e
r C 2'9u Gr. ^°SIS and the construction of this dam option will probably be
finished at least one season before the clay core option
Baro Volume 4A Geology - 14 September 2006 doc NORPLAN - NORCONSULT — LAHMEYER JV
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The concrete faced rock  fill darn has  been selected for lhe Prefeasibility design An asphalt core dam may  be further investigated during detailed design, as  it has  some technical advantages  as  well as  advantage for lhe construction progress  under wet weather conditions  A concrete op tion has  been ruled out because of lhe foundation conditions  as  well as cost Clay  core rock  fill dam might have slightly  lower direct construction cost However, lhe wet weather conditions  in the Baro area are disad vantageous  for construction of clay  core Because of the size of lhe dam. nsk  of many  and long halt periods  for clay  compaction works  may seriously  affect the construction progress  and thus  the cost. An asphaltic concrete core dam would be technically  feasible under lhe prevailing conditions, but would give higher cost
Foundation of lhe planned concrete face plinth will be located well into the residual soil formation at sufficient depth to achieve satisfactory  low seepage gradient around the concrete foundation as  recommended in Table 10-1
Saddle dams  of modest heights  at two depressions  to lhe right of the main dam will be constructed as  clay  core embankment dams  Because of the small size of the dams, construction should be possible during one dry season
A  tunnel  to  divert  the  water  dunng  dam  construction  is  foreseen  through rock to lhe left of the spillway structure
10.2
Subsurface constructions
Locations of subsurface constructions are shown in the Baro 1 geologi
cal map, Drawing Ba1-E01 and Geological section of waterway, Drawing
Ba1-E04 Dimensions of tunnels, shaft and caverns are shown >n Table
10-4. Toal tunnel length for Baro 1 is in the order of 4 4 km (power
house cavern and transformer cavern excluded)
foro Vo'ume 4A
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Table 10 4 Baro 1 underground constructions, dimensions
Construction / shape (D-
shape (D) or circular (C>)
Width*Height, m
/ Cross-
sectional area,
m2
Headrace tunnel / D
8 5*8 5 / 64 5
Adit/surge tunnel / D
7*7/43 7
Length, m
2440
910
Headrace shaft, unlined / C
Headrace tunnel, unlined / D
Steel lined penstocks and
bifurcation / D
Surge tunnel 1 D
Tailrace tunnel / D
Access tunnel / D
0 8 5 / 56 8                  106
8 5*8 5/64 5                35
Various
J
Various 
______________
10*10/89 3                  286
8 5*8 5/645
7*7/43 7
920
'510 1 ...
225
155
..
1
Transformer hall tunnel / D            5*7/32 3
Tunnel to rock trap / D I 5 5*5 5/27 2
Cable tunnel / D
Power station cavern, D
5 5*7 / 35 3
664
19*39
60
Transformer hall. D                    T 14*16
+7,       J
10 2 1
Descriptions and discussions in the following cover the main tunnels 
Feasibility for the minor tunnels is depending on the conclusions for the
main tunnels and is not considered of importance in this discussion.
Headrace tunnel and shaft
General
The concluded Baro 1 headrace system includes a 2440 m long head
race tunnel with 64 5 m cross-sectional area and at the downstream
en o this, a vertical 106 m deep shaft with 56 8 m  cross-sectional
Ie ?!otlVe e,eva"on 0< ,he intaRe is 1470 masl Elevation at top of
shaft is 1421 masl. Depth of tunnel below terrain varies from less than
50 m to about 250 m.
Ground conditions predictions
The headrace tunnel is  expected to be located in rock  mass  consisting of Precambrian gneiss  (migmatitic) in its  full length Such rock  has  been con irme y  exposures  both close to the intake and at some locations along the tunnel alignment
Exploratory  core drilled boreholes  along the headrace lunnel indicate in general moderately  good rock  mass  quality  see Chapter 7 2 3 The rose diagram in Figure 10-2 shows the orientation of the mam part of the tun-
2
Bam Volume <A
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nel in relation to joint orientations. Line with arrow end points  shows  di rection of the headrace tunnel, with circular end points  direction of axis of power station cavern, with square end points  approximate direction of access tunnel and tailrace tunnel
T
MM
P«*«vK4*«
«•••• 
r .4
■ •*>M44a MO.nPlIin
• cc
Excavation
Figure 10-2 Baro 1 Rose diagram with statistical distribution of joint strike onentations
Ground engineering prediction
Excavation   of   the   headrace   tunnel   is   anticipated   done   with   only   one work face, from the power station towards the headrace shaft
The headrace tunnel is planned excavated by drill-and-blast methodol
ogy and use of wheel-based equipment for excavation and mucking
One possible method for excavation of the headrace shaft is  by  drilling of a small-diameter pilot shaft and then widen it full size by  dnll-and-blast excavation Shaft-sinking is  considered not optimal due to too high mobi lization costs for such a short shaft
Sounding /grouting Permeability  tests  in exploratory  boreholes  show in general low to mod erate permeability. Amount of leakage water into the headrace tunnel is expected moderate, but locally  high permeability  in the rock  mass, with risk  for unacceptable ingress  of water, may  be encountered Dnllmg of sounding holes  in front of the tunnel face may  be necessary  in parts  of the tunnel for investigation of leakage nsk  and for assessing need for pre-grouting Pre-grouting is  done in front of the tunnel face allowing h'gher grouting pressures  than with grouting behind the tunnel face, and better results are achieved
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Rock support needs          In general moderate to good rock mass quality is expec e a
Baro 1 headrace tunnel, both in regard lo rock strengt an 9
fracturing or jointing Rock support consislmg of comb'na ion
bolts and sprayed concrete will normally be sufficient Expece ro
support alternatives are scattered bolting of individual blocks, sys emai ic bolting sprayed concrete or combination bolting / sprayed concre e
High capacity rock support may be necessary in clayey fault zones, highly tentative and assumedly conservative assessment of rock support needs is presented in Chapter 9.8
10.2 2
Power station complex
Chosen location of the Baro 1 power station cavern is at approximately 
N892 350 E756 770, with a depth below terrain of approximately 270 m
Dimensions of the cavern are L*W*H = 60*19*39 m Elevation of the roof
is planned to be about 1341 masl
Ground conditions predictions
The rock mass in which the power station cavern is planned excavated
is expected to be of good quality, with high rock strength low to moder
ate degree of jointing low permeability and moderate rock stress level
Exploratory borehole B1T-4 is located in the order of 200 m N of the ten
tative power station cavern location Rock mass quality in this borehole,
assessed from RQD values, is in general very high, see Table 7-4 Very 
high rock quality was also found in nearby rock exposures
Design considerations
Chosen location of power station cavern, concluded on basis  of ex pected ground conditions  and rock  stress  considerations, is  a tentative, rough location, see Chapter 9 9 Final location of the power station is suggested done during excavation of the access  tunnel On basis  of in formation on rock  conditions  obtained from excavation of the access tunnel from additional exploratory  core drillings, as  well as  rock  stress measurements, detailed location of lhe cavern can then be concluded
Onentation of a power station cavern is  often governed by  the orienta tion of the dominating discontinuities  in the rock  mass. Normally  orienta tion of the cavern parallel to the dominating discontinuities  should be avoided due tc  negative influence on the stability  The tentative orienta tion of the Baro 1 cavern is  chosen on basis  of assessed onentation of geological discontinuities see rose diagram in Figure 10-2
Ground engineering prediction
Excavation of the power station cavern is  intended done as  staged ex cavation. with continuous  rock  support construction Rock  support is  ex pected to consist of continuous  sprayed concrete in combination with systematic  rock  bolting above the machine hall floor, and discontinuous sprayed concrete in combination with scattered rock  bolting below Phi losophy  for rock  support in power station caverns  is  descnbed in Chap ter 9 7
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10 2 3
Tailrace tunnel
General
The concluded Baro 1 headrace system includes  a 2460 m long head race tunnel with 64 .5 m3 cross-sectional area and at the downstream end of this, a vertical 106 m deep shaft with 56 6 m? cross-sectional area Tentative elevation of the intake is  1470 masl Elevation at top of shaft is  1421 masl. Depth of lunnel below terrain vanes  from less  than 50 m to about 250 m Sufficient rock  cover is  expected for the entire tun nel.
Ground conditions predictions
The headrace tunnel is  expected to be located in rock  mass  consisting of Precambnan gneiss  (migmatitic) in its  full length. Such rock  has  been confirmed by  exposures  both close to the intake and at some locations along the lunnel alignment
Exploratory  core drilled boreholes  along the headrace tunnel indicate in general moderately  good rock  mass  quality, see chapter 7 2.3. Figure 10-2 shows  the orientation of the main part of the tunnel tn relation to
joint orientations
Ground engineering predictions
Comments    regarding    tunnel
excavation, Chapter  10.2.1
rock are
support    and
sounding
I  grouting,
given  in
also  valid
for
need    for the  tailrace
tunnel
10.24
Access funnel and cable tunnel
General
2
The access  tunnel has  a cross-sectional area of 44 m and a length of
approximately   0   5   km.   The   cable   tunnel   cross-sectional   area   is   35   m?
and   has   a   length   of   approximately   0.7   km.   Bolh   portals   are   suggested
placed in an area with exposed rock
Ground conditions
The   tunnels   are   locaied   within   Pre-cambrian   gneiss,   with   expected   suffi
cient   rock   cover   ancf   acceptable   rock   conditions   for   establishing   tunnel
portals   With   reference   to   exploratory   boreholes   B1T-4   and   B1T-5   is   ex
pected   moderate   -   high   rock   quality,   possibly   also   low   -   moderate   qual
ity  In B1T-4, more than 90% had RQD classified as  Very  high in B1T-5
only 40%
Ground engineering] prediction
Rock   support   needs   are   expected   taken   care   of   by   rock   bolts   and/or
sprayed   concrete   Expected   rock   support   alternatives   are   scattered   bolt
ing   o   individual   blocks   systematic   bolting,   sprayed   concrete   or   combi
nation   bolting   /   sprayed   concrele   High   capacity   rock   support   may   be
necessary if major fault zones should be encountered
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11                         GROUND ENGINEERING PREDICTION - BARO 2 AND GENJI
11.1
Baro 2 and Genji dams
The topography  and ground conditions  on Baro 2 dam site as  well as  the size of the dam differ considerably  from Baro 1 dam, At the right side of the river the terrain rises  gently  away  from the river Good competent granitic  gneiss  rock  is  found at shallow depth all way  up to dam crest level Bedrock  is  exposed in the nverbed At the left nver bank, the ground surface rises  steeply  from the nverbed In the ndge. residual soil and basalt boulders  cover in-srtu basalt rock  Underneath the basalt a severely  weathered or decomposed gneiss  of high permeability  has been identified as  transition to sound gneiss  Figure 11-1 shows  a longi tudinal profile in the dam axis  The profile is  also shown on Drawing Ba2-E02
The dam is  designed with a concrete spillway  and intake structure lo cated at right river bank  Clay  core rock  fill dams  have been proposed on both sides  of this  concrete structure It is  expected that construction progress  and costs  will be significantly  influenced in case of poor weather conditions, due to the relative small size of the dam The dam construction is  not on critical line, and construction could be planned for favourable seasons  Suitable construction materials  (clay) for the clay core are available, as  is  suitable rock  for rock  fill as  well as  for concrete aggregates
High permeability  in the transition between the gneiss  and the above layer of basalt in lhe left bank  ridge requires  special precautions  to pre vent unacceptably  high seepage gradients  through the ground High seepage gradients  could cause internal underground erosion and leak age within the severely  weathered / decomposed rock  Various  solutions such as  deep slurry  trench walls  or jet grouting through the basalt into the weathered zone as  well as  application of an ‘impervious" clay  blan ket along lhe upstream side of the ridge have been considered The lat ter solution has  been adopted for the present design as  conservative worst-case solution. However, the permeable layer should be further in vestigated during detailed design phase before final solution is selected
The Genji dam site is  located in a relatively  narrow V-shaped valley which calls  for a spillway  structure within the dam. see Figure 11-2 and Drawings  Gen E01 The ground conditions  are favourable as  rock  is  ex posed m the nverbed The soil cover in both abutments  is  shallow in lhe magnitude of 0-5 m
The   ground   conditions   are   favourable   for   a   massive   concrete   dam   in cluding spillway and intake structure
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Volume 4 A
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*
LEGEND
AiIlMupi detain and mm
Fk*dud cm
PligtCCWM Plylc MM! n<7«
Blgdtv o<TX)QnM, mkw tfctini gnatai
Wachorw prt □* c*w* w*»
**™£D WEAKNESS JONES
I         ZtfUWUtticfiffl
II        iorwWkWia iCm
LU 2fi*wVtah > 1Qm
UDI
Eaptfatatry tmtwM
Figure 11-1: Geological profile in Baro 2 dam axis, showing quite different foundation condition an the left bank and nght bank
Ba'D Volume 4A - Geology - 14 September 2DC6 o-oc
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Figure 11-2 Geological profile in Gonji dam axis, showing favourable foundation conditions for a massive concrete dam
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Subsurface constructions
Volume 4 A
Page 11-4
' „.2
Locations  of subsurface constructions  are shown in the Baro 2 geologi cal map. Drawing Ba2 E02 Dimensions  of tunnels, shaft and caverns are shown in Table 11-1 Total tunnel length for Baro 2 and Genji is in the order of 27 3 km (power house cavern and transformer cavern ex cluded)
Table 11-1 Baro 2 underground constructions, dimensions
Construction / shape (D-
shape (D) or circular (C»
Width*Height, m / Cross-sectional area, m’
Length, m
Headrace shaft, unlined / C
08 5/56 7
50
Headrace tunnel, unlined / D
8.5*8 5/64 5
6140
Adit / D
7*7/43 7
832
Surge shaft unlined / C
0 8 5/56.7
180
Headrace shaft, unlined
08 5/56 7
277
Headrace tunnel, unlined / D
8 5*8-5/64 5
152
Steel  lined  penstocks  and  bi* furcations
Penstock 05 0 bifurcations 02 6
72
20-40
Tail race tunnel / D
.
10*10/89.3
6100
Surge tunnel / D
10*10/89.3
750
Adil / Surge tunnel / D
7*7/43 7
950
Access tunnel / D
7*7/43.7
1700
Access  tunnels  to transformer
hall
6*7/38 1
130
Tunnel Io Baro 2 rock trap / D
5.5*7 / 35 3
228
Tunnel to Genji rock trap f D
5 5*7/35 3
242
Tunnel to draft tube gates / D
4*5/18 3
135
Cable tunnel / D
5 5*7/35 3
1260
Power station cavern. D
20’51
133
Transformer hall D
15*17
174
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Table 11-2: Genii underground constructions, dimensions^_____________
PConstruction / shape (D-shape (D) or circular (C))
I
Width-Height, m / Cross- sectional area.
12
m   _____________
Length, m
Intake shaft, C
06 0/28 3
30
Headrace tunnel unlined / D
7*7/43.7
5930
Adit
6 5-6.5/37.7
610
Adit / surge tunnel / D
7*7/43.7
775
Headrace shaft, unlined / C
07 0 38 5
270
Headrace tunnel, unlined / D
7*7/43 7
220
Steel lined penstocks  and bifurca
tions
Penstock 03 4 Bifurcations 02 3
90
30-35
11 2 1
Baro Volume 4A
Descriptions and discussions in the following cover the mam tunnels 
Feasibility for the minor tunnels is depending on the conclusions for the
mam tunnels and is not considered of importance in this discussion
Baro 2 Headrace system
Genera!
The concluded Baro 2 headrace system consists  of an about 50 m verti cal intake shaft and a 6 14 km headrace tunnel with 64 5 m2 cross- sectional area Tentative elevation of the intake is  1304 mast Depth of tunnel below terrain vanes  between about 60 and 200 m At the lower end of the headrace tunnel is  a 180 m long vertical surge shaft and a close Io 300 m long headrace shaft Access  to the Baro 2 headrace tun nel is through a 0 8 km long adit, placed centrally in the headrace tunnel.
The headrace system in Genji consists  of 30 m long intake shaft of 28 m2 and a 5 9 km long headrace tunnel of 44 m2 Maximum depth of the headrace tunnel below terrain is  about 200 m. A0 6 km long adit is  con nected to the headrace tunnel In the lower end of the headrace tunnel is placed a close to 0 8 km long surge tunnel and a 270 m long headrace shaft
Ground conditions predictions
The bedrock  in the area of the headrace tunnel consists  of mainly  syn- tectonic  granites  Such rocks, assumedly  partly  with a gneissic  appear ance, are expected Io be encountered in most of the headrace tunnel In the lower part of this  tunnel may  be encountered paragneisses  of vari ous  compositions, including hornblende gneiss  and amphibolite Such rocks  have been confirmed by  exposures  as  well as  by  exploratory boreholes  They  are unconformably  overlain by  basalt lava flows  belong ing to the Mekonen Basalts  In borehole B2T-4 the boundary  between the overlying basalt and the underlying basalt is  found at a depth of about 20 m i e at about elevation 1297 mask. or about 160 m above the
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headrace  tunnel  The  basalt  was  not  encountered  in  other  boreholes along the headrace tunnel
Geological weakness  features  compnse foliation weaknesses, joints  and weakness  zones  The orientation of the foliation is  in general stable, with stake around N-S and low to moderate dip towards W Degree of jointing vanes, as indicated by the vanation in RQD values assessed for the core samples from the exploratory boreholes
As  shown in Figure 11-3. the direction of the headrace tunnel diverges from the mam joint direction. In regard to the stability  conditions  in the tunnel this is a favourable situation
14
SM'thcW 5iznfr**»
r
MO I
i •*•(**
*•«*’*-,
PeU’ew
Uaiaun Pt'MiUp
MM'Miiup u»m«<
DcoMun > 2* »«—««
'••««> Main Htiptiwv
(•«*•«••• al 1132 Pqi»«
CT
•4
8
Figure 11-3 Baro 2 Rose diagram with statistical distribution of joint stnke orientations
In Figure 11-3 above lines  with arrow end points  shows  direction of the headrace tunnel, with circular end points  direction of axis  of power sta tion cavern, with square end points  approximate direction of tailrace tun nel.
Design considerations
Chosen location of power station cavern, concluded on basis  of ex pected ground conditions  and rock  stress  considerations, is  a tentative, rough location, see chapter 9.9 Final location of the power station is suggested done dunng excavation of the access  tunnel. On basis  of in formation on rock  conditions  obtained from excavation of the access tunnel, from additional exploratory  core drillings, as  well as  rock  stress measurements, detailed location of the cavern can then be concluded
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Excavation
Orientation of a power station cavern is often governed y 
lion of the dominating discontinuities m the rock mass Norma y o i
tion of the cavern parallel to the dominating discontinuities s ou
avoided due to negative influence on the stability The tentative orien a
tion of the Baro 2 cavern is chosen on basis of assessed orientation o
geological discontinuities, see rose diagram in Figure 11-3
Ground engineering prediction
Excavation of the headrace tunnel is  anticipated done with two work faces, from the adit towards  the headrace shaft and towards  the shaft at the lower end
The headrace tunnel is p.anned excavated by dnll-and-blast method and
use of wheel-based equipment for excavation and mucking
One possible method for excavation of the headrace shaft is  by  drilling of a small-diameter pilot shaft and then widen it full size by  dnll-and-blast excavation Shaft-sinking is  considered not optimal due to too high mobi lization costs for such a short shaft
Sounding /grouting Amount of leakage water into the headrace tunnel is  expected moderate but locally  high permeability  in lhe rock  mass  with nsk  for considerable ingress  of water, may  be encountered Drilling of sounding holes  in front of the tunnel face may  be necessary  in parts  of the tunnel, for investiga tion of leakage risk  and for assessing need for pre-grouting Pre-grouting is  done in front of the tunnel face, allowing higher grouting pressures than with grouting behind the tunnel face, and better results  are achieved
Rock support needs In general good rock mass quality is expected along the Baro 2 head
race tunnel, both in regard to rock strength and degree of fraclunng or
jointing Rock support consisting of combination of rock bolts and
sprayed concrete needs will normally be sufficient Expected rock sup
port alternatives are scattered bolting of individual blocks, systematic 
bolting, sprayed concrete or combination bolting / sprayed concrete
High capacity rock support may be necessary in clayey fault zones
112 2                            Genji Headrace system
Discussion regarding the Baro 2 headrace system above, including ex pected ground conditions  and ground engineenng is  in general also valid for Genji As  shown m Figure 7-4, more than 90% of the GJT-1 borehole is classified with ROD High and Very high
11.2.3                            Power station complex
Chosen location of the Baro 2 power station cavern is at approximately 
N902 400, E 42 300, with a depth below terrain of approximately 280 m Dimensions of the cavern are L*WH = 133*20*51 m Elevation of the
roof is planned to be 839 masl
Ground conditions predictions
The  rock  mass  around  the  planned  power  station  cavern  is  expected  to be of moderate to good quality, with moderate to high rock strength.
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moderate degree of jointing, low permeability  and moderate rock  stress level. Exploratory  borehole B2T-4 is  located a couple of hundred meters east of the tentative location of power station cavern Rock  mass  quality m this  borehole assessed from RQD values  is  in general very  high, see Figure 7-7
Design considerations
Chosen location of power station cavern, concluded ■ a. on basis  of ex pected ground conditions  rock  stress  considerations  and potential surge shaft localion. is  a tentative rough locahon Final location of the power station is  to be done during construction With addilional information on rock  conditions  obtained from excavation of the access  tunnel from ad ditional exploratory  core drillings  as  well as  rock  stress  measurements, detailed location of the cavern can be concluded
Orientation of a power station cavern is  often governed by  the orienta tion of the dominating discontinuities  in the rock  mass  Normally  orienta tion of the cavern parallel to the dominating discontinuities  should be avoided due to negative influence on the stability
As  concluded in Chapter B 1, the most pronounced orientations  of fault zones  are with strike around N-S and around E-W, and with steep dip These directions  appear from the rose diagram in Figure 11-3 where also orientation of the power station cavern is  shown The cavern is  ori ented with the axis  N30°E Io minimize the influence of geological weak nesses
Ground engineering prediction
As  described for Bare 1 in Section 10 2 2 excavation of the power sta tion cavern is  intended done as  staged excavalion, with continuous  rock support construction Continuous  use of sprayed concrete is  expected in roof and in walls  above the machine hail floor See chapter 9 7 with dis cussion about rock support philosophy
112 4                           Access tunnel and cable tunnel
General
These tunnels are planned placed m the same area, assumedly with same ground conditions The access tunnel has a cross-sectional area of 44 m and a length of approximately 1 7 km The cable tunnel has cross-sectional area of 35 m  and a length of approximately 1 3 km
z
Both portals are suggested placed in an area with exposed rock
Ground conditions
The tunnels  are located within Pre-cambrian gneiss  Rock  exposures confirm sufficient rock  cover for the tunnels  and apparently  satisfactory rock conditions, with moderate - high rock quality
Ground enqineennq prediction
The   tailrace   tunnel   has   the   potential   of   being   excavated   with   up   to   4
wor faces  2 work  faces, one from the downstream portal, one from the upstream end and two from the adit The tunnel has  a downward gradi ent rom the upstream to the downstream end. At two of the work faces.
0JrO Volume 4A - Oology 14 Septan*,r 2006 dot
NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and VWVDSEFederal Democratic Republic of Ethiopia - Ministry of Water Resources
Volume 4 A Page 11 9
excavation will be with a downward gradient and pumping of leakage water at the face will be needed
Excavation                   The cross section area and gradients favour wheel-based equipment for excavation and mucking
ock support needs The tunnel is located within Pre-cambrtan gneiss Exploratory boreholes 82T-5 and B2T-6 indicate sufficient rock cover for the tunnels and ap parently satisfactory rock conditions with moderate - high rock quality A highly tentative and assumedly conservative assessment of rock support needs is presented in Chapter 9 8
84 0 7o'u,T*4A 14 Sep(eplt*r
norplan - norconsult' lahmeyer jv~
in association with Snebelle Engineering and WWDSEFederal De-noaatic Republic of Elh-cp.a M.mslry of Wafer Resources
Volume * A Page 12-1
12                        SEISMIC HAZARDS
The Geophysical Observatory  Science Faculty  Addis  Ababa Univer sity  has  specifically  assessed lhe seismic  hazard for Baro Dam site according to the methods  recommended in the Global Seismic  Haz ard Assessment Program The report "SEISMIC HAZARD ASSESS MENT FOR A DAM SITE AT BARO RIVER" from Geophysical Ob
servatory,    Science    Faculty    Addis    Ababa    University    November    1998
is enclosed as Annex 4 G
According to the Geophysical Observatory, there are 5 main seismo- tectomc  area sources  having different seismicity  parameters  contnb- utmg to seismic  hazard in Ethiopia These seismo-teclonic  source zones  are 1) The Southern Rifts. 2) The main Ethiopian Rift, 3) The Western Afar Margin. 4) The Afar Depression and Gulf of Aden and 5) the Red Sea The seismicity  parameters  for the dam site have been determined for each and every  source area considering data from all recorded earthquakes in Ethiopia and neighbouring countries
The results  of the study  are summarised in Table 12-1 showing ground motion amplitude in fraction of gravity  (gravitational accelera tion g) for different periods  of ground motion and for different return periods
Tabic 12-1 Peak Ground and Spectral Acceleration at 5% damping
Return period
Years
For hard rock site
10 HZ
5.0 HZ
10.0 HZ
Peak ground
acceleration
100
0.035 g
0.060 g
0 039g
0 040g
200
0 043 g
0 071 g
0 045 g
0 046 g
500
0 054 g
0 0B4 g
0 .054 g
0 054 g
1000
0 065 g
D.097 g
0061 g
0.062 g
5000
I 0 094 g
□ 12-* a
D0B1g
□ 0B2 g
According to ICOLD Recommendations  (Bull 72}, the site is  rated to Hazard Class  I this  represents  "Low Hazard" Most dams  in this  haz ard class  will not experience damage under the MDE (Maximum De sign Earthquake). It would be sufficient to check  the dam for the MDE using Ground Motion Amplitude for calculation. Design Earthquake should be selected at a return period of 200 years. The conse quences  for the design will be either only  slightly  slronger concrete or a slightly  thicker concrete cross-section For earth fill or rocks  fill dams it would mean slightly flatter slopes.
All structures  at Baro will be founded on hard rock  except for the con crete face stab at lhe Barol Dam right abutment and switchyard structures, which may  be founded on residual soil deposits  No sig nificant deposit of fine sand or silt, which would be susceptible for liq uefaction, has  oeen identified close to the anticipated engineering
structures 
y
sj-o vciu-e *A Gwioav M
20ce.doe. NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWOSEFederal Democ/ahc Republic of Ethiopia - Ministry of Waler Resources
Volume 4 A
Page 12-2
2
J
Induced earthquake The gross volume of Baro reservoir is approximately 17 km . covering
a total area of approximately 450 km  at full proposed supply level
The major part of the stored wale' will be within approximately 50 km distance from the dam The issue of Reservoir-Induced Earthquake should be evaluated during the Detail Design Stage The report.
Annex 4 G from the Geophysical Observatory, Addis Ababa Univer sity. mentions bnefly the experience gained from Kariba Dam at Zambezi River The reservoir is about 10 limes bigger than the Baro reservoir However, probable reservoir induced earthquakes have
been registered
Seismographs               In order to evaluate reservoir induced earthquakes the tectonic con ditions  with  identification  of  major  fault  zones  in  the  Baro  dam  and reservoir  area  should  be  studied  Furthermore,  seismographs  should be installed in the area as soon as possible in order to get better in formation on the impact from possible earthquakes that may occur in the future It is recommended that the Geophysical Observatory Sci ence Faculty.  Addis Ababa University is engaged to install and ob serve seismographs in the area.
Baro Volume 4A Geology 14 September 200$ <Joc
NORPLAN - NORCONSULT - LAHMEYER JV
,n association with Shebelle Engineering and VWVDSEc ederal Demoaalic Republic of Ethiopia - Ministry o< Water Resources
Volu me 4 A
LIST OF REFERENCES
References to documents in this list have been made in the report text by means of numbers 
in square brackets ()
Ref. No     document
Baro Akobo River Basin Master Plan Report, TAMS & ULG, 1997
n' 1
[2]
Bare Hydropower Projects, Pre feasibility Study Norplan & Norconsult, WWDSE/Shebelle Consult
[3]       Desk Study on Genji Diversion*, Norplan, Norconsutt & Lahmeyer Int, 2004
[4]
Geba Hydropower projects. Feasibility Study Report NorptarVNorconsult/WMDSE? Shebelle Con
sult 2004
Climatic Classification of Ethiopia, National Meteorological Services Agency (NMSA) of Ethiopia, Lemma Gonfa 1996. Addis Ababa. Ethiopia.
- --I
[6]      HEC-4 Monthly Streamflow Simulation Hydrologic Engmeenng Center, U.S Army Corps of Engi neers, Davis California. 1971
[7]
Manual  for estimation of probable maximum precipitation econd  edition OperationalHydrology Report No 1 World Meteorological Organization, (WMO-No 332 1986
IBJ     Stage II Feasibility Studies for the Beles, Chemoga Yeda and Halele-Wcrabesa Hydropower Pro- eels Lahmeyer International (EEPCo) 2004
[9]     Gojeb Hydropower Project. Final Design Review Phase. PMF Report. LEK-JV, (EEPCo) 1990
(10]    The prediction of storm rainfall in East Africa Report prepared by Transport and Road Research
Laboratory Report No LR 623, Crowthome, UK. Fiddes. DC. Forsgate. JA, Gngg. AO. 1979
111]   Bathymetric Survey for the Legadadi and Geffersa Reservoirs Final Report, AAWSA/TAHAL and
Assoc July 1999
[12]     Karadobi Multipurpose Project Pre-feas.biMy Study. Draft Final Report, Nor- [UarVNorconsult/Lahmcyer International July 2005
[13]      Aspects of Climate and Water Budget in Ethiopia, Daniel Gamaohu, Technical Monograph Addis Ababa University, 1977.
Bans volume 4A                      14 September2DM doc NORPLAN - NORCONSULT - LAHMEYER JV
in association with Shebelle Engineering and WWDSETHE FEDERAL DEMOCRATIC REPUBLIC OF ETHIOPIA
MINISTRY OF WATER RESOURCES
BARO MULTIPURPOSE PROJECT FEASIBILITY STUDY
Final Report
Annex 4 A Bore Hole Logs
September 2006BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1D-1
Borehole information
Total length, m
Casing length, m
Hole size, mm
Coordinates - GPS
Elevation, m asl,
Plunge f azimuth. °
Starting date
Completion date
Soil overburden thickness, m Depth to ground water table , m min.
E
N
Permeability testing
Test section, m
max Lugeon
6.5- 16                                           94 35-50                                            0
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
50 35
584
76
758950
890900
90
11 03 05
22.03.05
4.25
1.5
5 05
Coefficient of permeability k (m/s] 1.3E-6
0E+00
Sample depth, m 6.0. 23.7, 44.4
80
Test results and petrographic descriptions are shown in Annex 4DCOMPLETED 2SCiO5
STARTED: 11/0MJ5
~                     Client: MOW* Con Log                Barot
SolVrock type
DEGREE Of JORfflNG
Water
Loes
Ramins
(Uthotogy.
Waathenog degree,
Slronotn etc)
Mo  ofnauni (Oints/Run
I
RQD(%I ' I
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STARTED1 *11/0305
Client MOWR
Core Log 5Me 8aro1
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degree of jointing
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WoHiner degree Stre glT del
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I
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STARTED ”03.05
Con Log CWWiMOWR
Silt Barot
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vr
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COMPLETED 2403*05_____  ______ Soil/rock type
rilel.cr'
This Page
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I
DEGREE OF JOINTING
No of natural
jOifllSi'Fin
RQD(%|
Remarks jtJthology,
Weathering degree. Strength etc)
o »c zi o
so ia               7R vsmBARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1D-2 Borehole information
Total length, m
Casing length, m
Hole size mm Coordinates - GPS
E
N
50.24 10.3
76
759075
890970
Elevation, m asl
-
Plunge / azimuth, 0
90
Starting dale
30 03.05
Completion date
03.04,05
Soil overburden thickness, m
110
Depth to ground waler table . m
min.
6.7
max
22.3
Permeability testing
Test section, m
Lugeon
19-27 26
27-39 04
Coefficient of permeability k [m/s) 2.7E-7
4.0E-8
Laboratory testing
Sample depth, m
Uniaxial compressive strength
32.8
Petrographic thin section analysis
Test results and petrographic descriptions are shown in Annex 4D.COMPLETED 0SWO5
SHEET 1 OF 3
STARTED. 30/03/05
Cort Log
Client: MOWR Site: Berol
Dnlllx> i«m Onentabon
I ofc' Length WK* refer Mon ir
TM Page mm Mi Elevationai Ml 0 *o
Joint Surface
VR
R Rc-jff
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H
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••
DEGREE OF JOWTtNG
No of nature'
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RQOf%]
m
c
□
N
£J
£
r
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£
I
8
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!
3
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or    □      c
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nn
RenwfeS (Uthotogy.
Worttienng degree Strength etc)
5
at
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10 WSHEET ? OF 3
STARTED 3CW3/OS Cora Loa Chant MOWR
Core Log SHe Bmo1
COMPLETED 93/04 05
Joint Surface
VR Very rough
R Rough
Zone*
Drillhole P^P?          Onerlabon           Sm Smooth
Total Length m** Inebriation w V$m Vary nu*
This Page IP       ••■£ i«vabor«-            O No y?nl» DEGREE OF JOINTING
|----- 1 F*eeiorr L^B Jo<Mr£
No. of natural
jCHnts/Pun
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3 Is
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nr
r*'
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1 ’
RQD(%]
e
.i
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s
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I
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100
1 ar
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852
2 01
97 S
voa
100
300
M
7 37
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252
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150
100
0«
100
1.70
MS
LOGGED BY A0IYE TAFFESSE
DRAWN BY TSEGAYE MEKURIASMARTED; 3OC3KJ5
Cori Lm Client: MDWR
Slt»: Barol
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EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1D-3
Borehole information
Total length, m
Casing length, m
Hole size, mm
70.4
22.9
76
Coordinates - GPS
Elevation, m asl
Plunge I azimuth, °
Starling date
Completion dale
Soil overburdon thickness, m Depth to ground waler table , m min.
E
N
max.
759280 891120
60 I N235E 04.04 05 07.04.05
20.0
10 8
17 5
Permeability testing
Test section, m
21-29
Lugeon
10,0
Coefficient of permeability k [m/s]
1.2E-06
29-36
0.0
0 OE+00
37-45
0,0
46-56
0.0
56-70
0.0
O.OE+OO
3.0E-09
O.OE+OO
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 23 4. 23.9
Test results and petrographic descriptions are shown in Annex 4DDepin
X
?2
-r
u
8
u
r
j:
3I
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;
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I
Drill Length Li•■■« ieccwerv<%'|
Tested aocions
r-
I
<?
3
CA
3
5
nt
rn
m
£ Sl._
f?5f
I 1-4
9
. n, e
a % $ er
A
»aSTARTED M/04/05
COMPLETED 07/M/05
U , „ 
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911.: B.ro1
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vR Verr'nujr
M «toM»e
t Drillhole »«
pi OnentationfiiJMs^ sew
Total length
mtn Inclination •£
g
This
DEGREE OF JOINTING
No of natural
Water
Loss
Remarks
(Lithotogy.
Weafhcnnfl degree
Strengtt etc)
•omls/Run
RQOf%) |
logged by abiye taffesse
drawn BY TSEGAYE MEKURIASHEET 3 OF <
COMPLETED. 0M*V5
STARTED 04/04/05
Client:  *0WR Site: Berd
Joint Sutfic*
Con Log
Drilhoie H22
|vh ’-*3
T
r
R Rough
Oncntabor             tmoor
Total Lmgtnmoffl inclination $£ Ths P»ge <*     lt^l«vrton JMMi
degree of JOINTING
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STARTED. 04/044)5
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Drillhole 1103            Onanlalion Total Lcnglh              Inclinalior er This Page W T4—mElavation
degree of jointing
No of natural jomts/Run
COMPIFTED 07 0*‘05
SoiUrock type
II
I 4ind tc*rl
Water
Loss
Remarks
(Urology
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Strergt^ ®’c>
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r
L 69
1 70
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1^72
73
LOGGED   BY   ABfYE   TAFFESSE DRAWN BY rSEGAYE MEKURIA4BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1D-4
Borehole information
Total length, m
70.3
Casing length, m
21 0
Hole size, mm
76
Coordinates
E
75962021
N
891337 78
Elevation, m asl.
1453.01
Plunge / azimuth. 0
60 / N55E
Starting date
05.04 05
Completion date
12.04.05
Soil overburden thickness, m
20.0
Deplh to ground water table . m
min.
15
max
5 05
Permeability testing
Test section, m 17,5-22
23-30
Lugeon
Coefficient of permeability k [m/s]
(Falling heads test)       1.5E-O7
3.0
3.0E-07
30-40
0.0
2.0E-10
40-50
0.0
1.0E-09
50-70
0.0
4.0E-10
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 20.6.51.3, 66.2 51.5
Test results and petrographic descriptions are shown in Annex 4DSTARTED: 0504^5
Client     MOWR
Site: Bard
Oiiihole bum Orientation a
Tota Lengih rojom In oral on jr This Page MMMft E ievaion
DEGREE OF JOINTING
No    01    natural
jointi/Run
Joint Surface
a Rough
/S'-      VerrirKMifh
a     OMo or-n
1--------
COMPLETED :204 0S Zones
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3
3
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Core Log C,*m* *0**
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; Th« P»KEMjH«W«f lemons... Hr
COMPLETED: U'04-05
SHEET 2 OF 4
Joint Surface
V* Very rough R Rough
■^Smooth
'VSm Veryvnoce
SoiUrocktype
<*■*- te*« *•«*
-IoNcm
degree of jointing
No. of natural lOiMVR-jn
£
Water
Loss
I1
Romafks
(L»(hotogy.
Weathering degree.
Strength etc)
J.
0
h- lugeon
QMlrtj tetitpjuc gnam
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great
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L OGGFD BY ABiYE TAFFESSE
drawn BY TSEGAVE MEKURIACOMPLETED 12W05
STARTED
” Cort Log Cli«nl: MOWR
Site: Berol
Joint Sixtece
|VR Vary
Ir
Oilbote I KM          OrtenlBtor adK.^ s™r Total Length/raw inelmMior •£ vsmvanw"®* T M PagegMjftjfef leva tom Mnni o no pmn
DEGREE OF JOINTING
No of natunl
foint^Run
RQD|%|SI AR TED 05/04/05
COMPLETED-12/04/05
i ™ Client: MOWR
Joint Surface
Zonefl
ISoWrock type
C<X*LOS StaB^I
<’M
mug*.
R Rough
DnKhole   bum   OnenlaOon   N»—
L Sm Smoofi
Total Length ZLHe. Inclmabon j£
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g
DEGREE OF JOINTING
No. of natural
ictnlij'Run
RQO[%1
I
Water
Loss
Remarki (Lrthotogy
Weathering degree Strength etc)
luflBOrt
-57
68
72
73
E 79
logged by abiye taffessl
DRAWN BY TSEGAYE MEKURIAIBARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1D-5
Borehole information
Total length, m
60 36
Casing length, m
Hole size, mm
5329
76
Coordinates 
E
N
75990021
891511.79
Elevation, m asl
1526 2
Plunge I azimuth. °
90
Starting date
10.04 05
Completion date
14 04 05
Soil overburden thickness, m Depth to ground water table . m mm
max.
51.3
8.64
14 7
Permeability testing
Test section, m
9.6-21
23-32
33-38
40-47
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Lugeon
Falling Head lest Falling Head test Falling Head lest Falling Head test
Coefficient of permeability k [m/s]
3.0E-07
1.3E-07
2.3E-07
1.0E-07
Sample depth, m
52 79
39.5
Test results and petrographic descriptions are shown in Annex 4DS FARTED 10/04/05
J Con Log Client: MOWR
Silo: Bico1
Qiw Onontabon Total Length WM* Inchrwton ir
COMPLETED: 144M/0S
SHEET 1 OF 3
Joint Surfoc*
VH VerynMJf*
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vSr Ven-mor*-
TM Page goc-MP+nEkevatonJBW□ MJonn
— ~—I
§
5
DEGREE OF JOINTING
Mo of neural
jants/Run
RQO(%]
i
♦0       X)0
5D 100
VR VSfflSHEET 2 OF 3
STARTED lO'DA’CS
Client. MOWR
COMPLETED 14.04,05
Core Log
Dnllholc »1M
Total Length «>"
Barof
Oriental on
Joint Surface
• H *♦*> -oust
R Riyj^i
rwns^oar
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3 r<l©d.*>r:
SoH/rock typ*
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This Page W0»4flW   £ levaho'
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DEGREE OF JOINTING                   3
i
X
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io 5 J
x I?
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Weathering degree.
SlrongH* ole i
c
3F
a
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/
t
§
8 & V &J
t
i
?
Water
Loss
LOGGED  by  AfilYE  TAFFESSE PRAWN 8Y TSEGAYE MEKURIACOMPLETED. 144M/M
___
SHEET 3 OF 3
STARTED 1CMW0S
Joint
Surface
Zon»t
So It/rock type
C«. L0fl C!i’nl “OW'R
3ti»: B*<o1
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DEGREE OF JOINTING
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RQD[%]
-J      1
S□ o
I
Loss
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Wealfwnng degr«. Stroftfllh Etc)
E
1                 IQ
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130
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704
2SJ
T»
■ 23
w
Lb-3sGGEDEfl*OH* **
E?i> •«»«
VETWTf“L.BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1D-6 (Quarry site) Borehole information
Total length, m
30.1
Casing length, m
2.5
Hole size, mm
76
Coordinates
E
758408.2
N
891799.8
Elevation, m asl.
1539 7
Plunge / azimuth. 0
90
Starting date
13.0505
Completion dale
14.05.05
Soil overburden thickness, m
56
Depth Io ground waler table , m
mm.
96
max
16.6
Permeability testing
Test section, m No tests
Lugeon
Coefficient of permeability k [m/s]
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 12 3.14 1. 18 8,28.9 12 5, 29.3
Test results and petrographic descriptions are shown in Annex 4D__ STARtfd 1105.05
COMPLETED: 140S--0S
Client  MOWR
She
*Driihoie mo;;
Tata length
Barol
Orientation
Inclination
rawdlumi
•:7W Jmr'W
CmsheC
TM Page                   f levaicn j
DEGREE OF JOINTING
to o’ natural
lorWRun
RQ(X%|
Sol/rock type
SaEp inr twewgrt^ss
■■Xarv 'rtMpMK OcL-te r**« jjjaQu*-J «eld»piic
■BAni|;NC*->iW
W»» *.• ruU>« 1 ..a,* —!
Mn
SSi
j
.0.
IBM
Water
Loss
Ramarks
(I itholofly, Woalhetrtg degree
SVcnglh etc)
l •.«o«v
ow
100
OK
100
SCO
100
□ so
too
• w
’00
etc
too
Light Q<*r mkiv v-i
111
too
072
100
2M
10a
Mesh white a<vj
l>-«‘ :oarie crwr Quarts
Inltspa-.c pntiu Miih >■
boiite or| turfac* «
1 5*
’«
M
1®
1M
too
1 4S
100
t-»»$r pnk am •* w toarsw y»r
‘*U»OBbC gneiss
1’M
•x
OU
100
»S7
100
Fixibdar* vwf'ile
•TC >-• rjJBiu reUspaw
**••» with I*. r<tw
- uGEDB* ABlYETAFFESSE
^awn bytsegayemekjria
—             r-^r,5HEET20F2
STARTED 13-DS05
Client MOWR
Core Log 5jll> B>fo1
□rillltote ■!»               Orientation iTolaU    gngth    Mill    Incfrialion    •£
COMPLETED 14 05D5
1 Tb-s Page
Soil/rock type
C .< txrtfr
tKfili r*" Ken: ’•du** »<*« QuM-j InWW-atc crp*i An^itc*W
levalion oyM
DEGREE OF joimtimg
Na of nature.
joints/Run
RQDIS]
Water
Loss
Remaps
^iibotoqy.
Weather cfoQ»<*
Slrrngtn etc)
26
27
I *»aft pnb «nc
y»A
LOGGED BY AB'YE TAFFESSE
DRAWN BY TSEGAYE MEKURIABARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1D-7
Borehole information
Total length, m
Casing length, m
Hole size, mm Coordinates - GPS
Elevation, m asl.
Plunge / azimuth. °
E
N
50.0 5,1
76
758850 890830
-
90
Starting date
05.04.05
Completion dale
08.04.05
Soil overburden thickness m
4.4
Depth to ground water table m
min
98
max.
11.7
Permeability testing
Test section, m
Lugeon
Coefficient of permeability k [rrVs]
7,5 - 16
18,0
16-31
0.0
30 - 50
0.0
2.0E-06
O.OE+OO
0.0E+00
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 13.9. 27.8. 46.9 28,3, 46 8
Test results and petrographic descriptions are shown in Annex 4D.COMPLETED 0BW05
STARTED' OMWW
Core Log CliwUHWR
Site: Berol
Dr JiqHj up? Onertabnr
Joint S jrfacn
r Hwjr
Sni JrecTi
firi
Total Loncth M Mm Incitation W ■,^3rtl '.'fry
TNs Pape o w-M.Bew-ElevaborMtto-w  dON&pn" DEGREE OF JOINTING
Na  al  ratura
Water
Loss
£
Q.
Remarks (.lilFiotogy
Weathering dog^ Suenoth «tc)
jCNntAfiun
RQD(%|
J 57
M«1
D»
H’fl
OH
S71
1W
■DU
7.1JT
iaa
142
IDO
1 JO
45fl
I *»
100
»Jn
i.K
3.G0
1PQ
3K
IM
'
BY AfilYE TAFF ESSE
I ftY’SEGAVEMEKURIASTARTED 05/04/05
t ™ Client: MOWR
CO"LOa 3... Bvo1
Onimo*e aiOT Orientation Tota’ Length Inclination
DEGREE OF JOINTING
No  of  natural
jotnti/Run
COMPLETED 0*0*05
Zone*
SoIVroc* type
£
Water
Loss
Remaps (Lithology.
Weathering degree, Strength etc)
8
o fo »o
ROO(%1
» 100 VR VSm
1
•o
•3d
JOO
100
• tl
•oc
While                   end Q'«y rnarw
grar
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2 1*
100
<*th    rereBton    of    dark    jreai )c ealk/n grain
•«                   slrwoar »’ 'l.t
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in
100
2 01
too
1*1
10
IBt
M4
1,71
•oo
»*wW- da<k gray fwa toMapatiC e raw gnwie
•W’ QuaHx Stanger rr-nwrrg i
■I 34.71m
1 10
100
081
100
1 •>
too
• st
•oo
LOGGED  BY  ABIYE  TAFFESSE DRAWN BY TSEGAYE MEKURIAGOMPlETfD M.04-^5
SHEET 3 OF 3
STARTED 0^-04 Q5
Cqf.Loa Cli.nl: WOWR
Sits; Barol
Dr.iiboie Btp? Oriental
Tnlai LftXflh W*4w rncfiniLkJfl ' This Fag* w
degree of jointing Nc  ol  natural
Zonas
msdp^i
Joinirtl
Eci Cnjshsd
ScMl'rock type
— -
a?
«i
o
E                   Water
1
£
?
s
1
Loss
•C
iDinttiRun
□
L._
0
ir .xi q
ROD[B'r‘
sc im
6
■j
,F W5«i
-*1 c E
&
c
□
3=¥ cr            □         5
g
CL
s
k— --flMXi
Remark
(LHhotofly,
•feathering degree.
Strength dtc)
n>
■j
d 12
J
in
Si«
j*
++
■ »■
+■
T ■"■
. *■
pi; EEq BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1T-1
Borehole information
Total length, m
50.1
Casing length, m
Hole size, mm
Coordinates - GPS
E
N
9.0
76
758600
890620
Elevation, m asl.
Plunge I azimuth. °
Starting date
Completion date
Soil overburden thickness, m
Depth to ground water table . m min.
max
90
150305 22.03.05
54
3.7 9.6
Permeability testing
Test section, m 87 - 19.4
Lugeon
Coefficient of permeability k [m/s]
Falling Head lest          4.0E-08
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 433
430
Test results and petrographic descriptions are shown in Annex 4D.COMPLETED 22034)5
SHEET 1 OF 3
STARTED. 15/03/05
Core log Client MOWR
SHe Ben?1 Dnilhote it Orientation
Total Length M.Mffi Inclination
TM Page LP*NHa Elevatorsbra DEGREE OF JOINTING
No. O< natural
•ont^Run
Joint Surfict
tr
R RcMjn 5^5#noor
,s« Vfnrve 10 M>p*”
SoWrudi type
* 5        Water
RomarXs
1sI     Loss
(Lithology.
Weathering degree.
Strength etc)
ROO[%J| 5
i
$
>-
• 
IB             tsr
J
A
?«
N7
LV< » ■ * »* ’**J
<
QB
M.4
TO
X
IX
M4
103
Wi
OW
IDO
1 00
r
125
M2
o.sr
fM
0B
7>5
0,20
100
090
WO
♦ X
M
QJ1
K/ I
OW
100
OM
Ml
DM
M»
3X
1
TSt |
□ 52
MSTARTED 15/03/05
Con       Log         Chtnt              *OW*
Site: Barot
DnUhoe itn               Oner! a bon ur ' Total Length             Inclination jr
1 This PaoOQ W^f RRElevaboniMfctAi
COMPLETED. 22/03/05
SHEET 2 OF 3
Joint Surface
VR V»ry rougfi
R!W
S*r fx-«cr
VS TH v»ry vr«e
OMcjor*
Soil/rock type
33
w  Uu.-V f«MV**• O'— *jr0T’ihate
O®*" V**
DEGREE 0* JOINTING                           8 -
■J           Water
No. ol natural
lOlnt^Rur
<H
£•
&
i
1g
i
r f6Q>
!     Loss
RQD(%1
L
e            d9
1____
JC
8
a
1
g
sJ
2
s
8
Remarks
(Lithology
Wealher.ng degree,
Strength elc)
—;— “io“
LOGGED    BY    ABIYE    TAFFESSE DRAWN BY TSEGAYE MEKURFACOMPLETED 22/WJ5
SHEET 3 Of 3
STARTED;
Cprt Log
€,tont: MOWR
Site: BiroT
Drlllhci* tm                  Orlonlatan jjc;
Total Lergtfi
inchnafcor *£
This PmWjPMl.l*n£lEwaboA.MfcLkiX DEGREE OF JOINTING
Na    gfnflturvi
jonts/Run
RQD[%|
hii ■‘M wA V5m
I'BARO MULTIPURPOSE PROJECT ■ FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1T-2 Borehole information
Total length, m
Casing length, m
Hole size, mm
Coordinates - GPS
Elevation, m as!
Plunge / azimuth, 0
Starting date
Completion dale
Soil overburden thickness, m
E
N
Depth to ground water table . m     mm. max
Permeability testing
50.1
12 0
76
758300 890940
-
90
29 03.05 02.04 05
9.4 2.6
102
Test section, m
12.2-20,1
20-30
30-50
Laboratory testing
Uniaxial compressive strength
Lugeon
0.0
0.0
0,1
Coefficient of permeability k [m/s] O.OE+OO
O.OE+OO 1.0E-09
Sample depth, m
10 5. 16.6.16 7, 16.9.45.2
Petrographic thin section analysis
Test results and petrographic descriptions are shown in Annex 4DCOMPLETED 024MO5
STARTED. 2*03-05
^fcor.Lofl CH^tMOWR
Site Berol
Joint Surtace
vr vant -‘*0h
Soil/rock typo
jgj/z 
r
Wt
P fcMjf*
,<vr
D”hoe im Onenlaton
s-i *>oor
Q' — --•
Total lenQfh w fm Incinatipn       fil
VS(R VerysroOt*
Thu Page
E ievahpr ?■—Ml CNC
Romanis
OEGREE OF JOtMTING
Water
Loss
(Lnhotogy.
No ot natural
Weathenng degree,
jonliRun
Strength etc)
ACO<%’
QB5
------------ ---
•oo
100
<2
zoo
545
1 50
«7
15/1 X>» nrtur sand
300
40 J
224
567
2.55
♦00
s^rry •ejrw'td In k»V
pr* arvg /rr WMt crar-
7>anz ledspaSc tpiess
marratoiee *r u»-»
gr»«n n*Sxm grjn
0 75
100
2*5
♦ X
t-Sl
WJ
,-r».r,FDBV ADIYE TAFFESSt
& bytsegayemekuwa4
STARTED 29/03/05
CHanl: MOWR
i Core Log SJ|e; 0afo1
Online* HIZ               Onentahon Total LonQth            Inclmabon t£ This PagettMABBf nation JUI
degree of joimting
Ho ofn«hjr»
pints/Rur
COMPLETED- 02/04/05
Joint Surface Zonta
|VH Vaqr rt»jg*
R HiXiQT.
Smoot
vSm
J 0 No onn
I
Sod/rock
4
Water
Loss
Remarks
(Lithology.
Weathering ctegrec
Strength ate)
RQD(%]
so 100
I
l/»r
r ■“
logged er abiye taffesse
DRAWN BY TSEGAYE MEKURIACOMPLETED: QZlOMK
SHELF 3 OF 3
STARTED: 29/03/05
Cort Log Clhint: «Wm
SIM: Baroi
Drillhole im                 Ortent®l>ofl Total length m               Incl.nabor
ir
T hri Page
leva ton ■Mnl
Joint Surface
VI V*Tf
r. itojit
jVn Sriuvff'
VSrn
I (J *to f
s
DEGREE OF JOINTING
No.  of  nartKal
pifltft/Run
AQD[%?
id hi a                                55            ■*'■>
*
(oJ
©
at Water
Loss
¥
5
*-      Lugda"
Remarks (Lrthotamr.
Wealhenpg dngrM.
Strength etc)
£ __ 0.
1 !□
’is:
1
100-
11 GQ
100
UM
IDO ,
F>-vW*i «**/»» ind pw*
JT?r trw hJ
■ -< Jubc a®. lAatu i frvn e Jia a ln» ES~ D 75*
5^»*n
? 10
ITO
T 1?
IMBARO MULTIPURPOSE PROJECT ■ FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1T-3 Borehole information
Total length, m
Casing length, m
Hole size, mm
Coordinates • GPS
Elevation, m asl.
Plunge / azimuth, °
Starting date
Completion dale
Soil overburden thickness, m
E
N
Depth to ground waler table , m mm max.
160 9
44
76 757400 891810
90 18.03.05 23.03.05
3.1
47
27.8
Permeability testing
Test section, m
Lugeon
80-100
0,0
100- 125
0.0
125-150
0.5
151 -161
1.2
Coefficient of permeability k [m/s| O.OE+OO
1.0E-09 5.4E-08 8,0E-08
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m
64 2, 90 2, 113.3, 150 1 64 6, 113.3
Test results and petrographic descriptions are shown in Annex 4DSTARTED 10/O3/O5
Cots Loe, Cllantr MOWR,
Site: Barat
Ortflhole- ■■n           CHenlatiun              4
Total  Lengmi  aqjOm  Inclination  •£ Thu Page                  E -evatxxiiHtejjU
DEGREE OF JOINTING
N&  of natural
COMPLETED 23A3/D5
Zonas
Solt/rodi t™
ffW 1 frU Fl a UP LarfT3U~r1 T"’ |
L* ■
ill'
*-
.JK<J |
A
£
;
1r
7
c
1
jointi/Run
ROO(%|
11        £ 3
g Water
V Loss
•
E
k           Lj-^wnr
Remarks
(Lithology.
Wnalhonng degn?e
Strength etc)
bytsegayemekuria
t
:« ■          I--:< ill .'.i.STARTED 1M3JO5
COMPLETED: 23/03^05
Zone*
DnlihOo HQ Ornjntaton Tout lengthlilHEL Inclination This Page
No   ol   natural JoinWRijn
a:
»■'
Joint Surfice
R FUxxr
Sni SnsKJiri
VSm Vary truce*
J Q NtaKiiHtt
SolWrock type
Coe Lot
Site: Serol
Water
Loss
Rentals
(Ltlboloyy.
Weathering degreci.
Slrenqlh etc)
RQDF%1DetHH
3
••i
S|
8
a
I.
-------- .iuuhuwi
---------- i-r- -— -1
.
..
___________
I
------------ t------------ 1
I
X
j
4
■n
H
\>rrsi>rT'vZ
”                   >c>c          >£'>■ ■ < H'f:     ’             v t/1
><1
wk: TO"
’ u. 2 .  L 1         -U 2 u. '   z
|X<gX'M
D Jomi Surf acu
F 'VgoujB m atonal
Zones Rock type
w
8
w
«
M
3
8
s
£
**
a
8
8
1
8
8
«
«
8
8
8
8
Drill length Cort ’•COvory[%)l
Tested seel tone
,,«h»i
hiH’
i
I
3
COMPLETED 23 0105
SHEET 3 Of Bsheet 4 OF 8
COMPLETED. 2V0>OS
l, tM)3?05
Client: MOWR
Co " LOfl Site: B«n»1
DrMhote MH             Onanteton
i   Tote'   ieng»\JLtta   inclination   fr | This Pago&MJtJt-f tevalxxvJteLXX!
Soil rock type
Joint Surteca
VR Vnyrmo*1
R
SmSrwt
VSn, Vary •moo*
ONO pre
Zones
|—1 FO*dp**
tag•****
m FruaM
|
degree of joimtwg                  1 h
s 1
£
?
No o< nature'
' O,n“/Ru°
*
M
Remarks
(Lithology.
Weathe^ degree
Strength etc)
Root*)
■f
->
?22
I Ks 
-j
1
10      20 C                  50           100          Vt?       V5fl»
ICX5GED by abiye taffesse
DRAWN BYTSEGAYEMEKURiASTARTED 1B/O3TO5
• Core Log     Cheri1 M0WR
Site: Berd Online on Or^i.1^
COMPLETED 23 03.05
SHEET 5 OF 6
Joint Surface
VR Very -utOh
A Hc-jof
Zones
Tout      Longit      <!■«*.      Inaction      ir     .^vnrw.- Thli P*g  Bft«Mfc£ievatcn "HsijJo^ ortj
‘•jlotfp't
HH .onlsfl
&L*3 Cashed
Soit/roch type
(Wtv>-
□a*rj               fir<ns Qaaru iMeicax tai* j*—m
<jneft3
8
o
DEGREE OF JOINTING
Nc ol natural
lO-tSJRun
RQD|%J
' Jv*TI
ArttiOo4l«
*•» hmm tynrt ■>•
kA-         1         Mo
L .« i rv |
* ??
3 2v
*?        it
3u
Water
Loss
Remarks
lithology,
Weathering degree,
Strength elci
it X» 3
50           100 VW •S'”
Luqkm
’
i0            *00
, , ______ ______STARTED 18/03/OS
COMPLETED 23-OJ05
SHEET 6 OF a
Cort Log
Client: MOWR
Site Barol
Dnil*ote tin                Onentalion
Joint Surface
VR Very rough
R RuuU»-
fwn Smoot’
Total Length              Inclination & o—  mVwSHyiVery WXjuF>
iu*C nr-
Jcrnlrt
Soil/rock type
CNrUr*’'
Qu<ru boi'H' p^iem
□u*rt/ littipu. ane*ss
Ougrtt *«n«Jaf»c flr*AS
| TM Page MJfcUUBf evaDon WPill{ o Ho
DEGREE OF JOIWT1MG
ATP* be Me
No of natu
ral
Water
Loss
wema'ks
llUMtOQV
jo«nls/Run
RQDf%]
Weathering degree.
Strength elc)
I 101
-106
I 107
Uoa
110
1-111
&12
1-117
LOGGED    BY
AHIYF
TAFFESSB
DRAWN BY TSEGAYF MFKURIACOMPLETED 2303.05
SHEET I OP 8
STARTED ia.'0305
MCoca Loa          Cliont MOWR Srta Baroi
MB^Dnlhcx Un C'lentaion
(Total Length i«M»» Inclinaf-or •r
So«Vrock type
-
“*■
' This Pago
ova! on
_!£__ ""J
DEGREE OF JOINTING
Nc otflAMal
jo^l^'Run
RQO(%]
•0 100
s
Water
Loss
o
si
k-
Hamarhs
(LMnotogy.
Wealhenng dograe.
SVvnglh etc)
LllQMB
1V
^121
122
123
-131
135
136
Ft 37
Fl 38
TSE&AVEMEKJRI*■
* fl1
•rr***'BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1T-4 Borehole information
Total length, m
Casing length, m
Hole size, mm
Coordinates - GPS
Elevation, m asl.
Plunge / azimuth. 0
Starting date
Completion date
Soil overburden thickness, m
E
N
Depth to ground waler table . m       min. max.
Permeability testing
166.9 9.8
76
757100 892630
■ 60/N190E
09.03 05 14.0305
84
3.9
194
Test section, m
85- 101
116- 128
Lugeon
0.1
10,0
Coefficient of permeability k (m/s] 5.8E-09
1.4E-06
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 16 2. 122.1 160 9
1225
Test results and petrographic descriptions are shown in Annex 4DSTARTED OW/05
Client- MOWR Site: B*ro1
Drillhole (it* □‘rientaiiCKi mw * ToiaJ i. »***■■ inclinal-on ar
Thij Page e<lM<Ae»F lovatoo •*-*!. DEGREE OF JOINTING
Na qU iialuol join If Hl n
3
IF ZJ-
c i? S5“o
—
PQD[%|
sc iw
VW
£r»5r-*
C«»
■--fciiM
Cr»jir** nr** -. nr»ta |jrfli|r
-
!.•
a»rh ind ;*■Ana i|u*r.J EM. 3 IS I qULLkLK |jhFU
of liniJl bp tfcgM*|r
t>*d i :*X L-m am‘‘I man >«p gntri 1e no r-hfi nlflBr**'
it i-cWhtftra*
C-Kj*
CaJD'jjSTARTED 09/03/05
C<x. Loo Cll.nt MOWR
SHe Barof
Drillhole it<              Orientals Total Length iiMw Inclination ar This Page It tMeJ0e£ levation m> l
Jo4nl Surface
• M                  ~x<r
Fl Hough
■> S/rocF
VSm Very inrzr
U                       0 No pints
COMPl FTED: 14/03/05 Zones
SHEET 2 OF 9
____________________
»41*3 pm*
Jointed
Cnjthec
SaVrocktypo
0ve*tunier
□u*tx oc *«
,
Qv^-j Meice ■' f*’ * V"*M O&rj ^v »‘c pnnn
IK
1 1
1*
l_
3
DEGREE OF JOINTING
No ol natural
jointa/Rcn
RQD(%|
2•
3 ol
f &a
IIE
s
i
*■
c
k.
8 1
V    Water
?
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•wBARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1T-5 Borehole information
Total length, m
Casing length, m
Hole size, mm
Coordinates - GPS
Elevation, m asl.
Plunge / azimuth, °
Starting date
Completion dale
Soil overburden thickness, m
E
N
Depth to ground waler table , m        min max
Permeability testing
80.1 4.3
76
757020 892870
-
90
09.03.05 01 04 05
2.0
03
4.5
Test section, m
Lugeon
40 56
0,6
52-71
0.0
52 80
0.0
Coefficient of permeability k [m/s] 9.6E-08
O.OE+OO O.OE+OO
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 36.6, 39 3. 543, 76 3 37.0
Test results and petrographic descriptions are shown in Annex 4DCOMPLETED 01 0W5
SHEET 1 OF *
3 I MH PEL* in31 U J'U-3
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Un
LK
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No       o’^u^l
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jla-j MHd’tpiadc-bd'V' 3ne "‘* ^rrxntioHfl
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AQ[)(%)
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Weathering degree
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LI_______________ ____ *          13             6
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3pre Loo Client MOWR
Site Bared
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Total Length R1»w Irclinntcr ir
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COMPLETED-O'iDMft
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7
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£ i
degree of jointing                   0 No at natural
& ts
Is
£
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I
II
w.»<no aamdwootBARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B1T-6
Borehole information
Total length, m
Casing length, m
Hole size, mm Coordinales • GPS
Elevation, m asl
Plunge/azimuth. °
E
N
502
20.4
76
756960 893330
-
90
Starting date
27 03.05
Completion date
29.03 05
Soil overburden thickness, m
198
Depth to ground water table , m
min
8.95
max
189
Permeability testing
Test section, m 21-32
35-50
Lugeon 0.0
0.3
Coefficient of permeability k [m/s] O.OE+OO
3.8E-08
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 22.3, 48 3
Test results and petrographic descriptions are shown in Annex 4D.Doplh
a
£
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STARTED 27/034)5
COMPLETED 29 03.05
Core Log
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soii/coc* *yp*
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drawn BY TSEGAYE MEKUR1A
FuSTARTED: 270105
COMPLETED: 29TLV05
SHEET 3 0 3
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OMaprti
Water
Loss
Remarks
(LrtNjIogy
Withering degree
Slrcrglh etc)
1 VWM1
1              10 -IX
-----------------------------SHEET 2
STARTED. 27/03/05
Cor.             Loo             ^MCWR
Site Bero1
Dnibolo tire                  Orientation total  L  engih  ?e.ihw  lnd»nal«on  KT I his Page ?ooe-M»9ef ‘eval*or
Joint Surface
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COMPLE TED 29‘03-05____________ SoWrocH type
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DEGREE OF JOINTING
No. ot natural
Water
Loss
]Oi"tS/Run
o
O
J             oa
ROOM       3            c
Romarkl
(Lithology
Weathering degree
Strength etc!
0         10 MO ’
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LuCeon
----- 7 ------id* * 1M
35
36
37
LOGGED SY ABIYE TAFFESSE
drawn by TSEGAYE MFKURIACOMPLETED 29W0S
STARTED. 27/01-05
C*r* Log Clfcenl: MWR
Joint 5urf»co
_         ___
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*4
-——BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B2D-1
Borehole information
Total length, m
Casing length, m
Hole size, mm
Coordinates 
Elevation, m asl
Plunge I azimuth, e
Starting date
Completion dale
Soil overburden thickness, m Depth to ground water table , m min.
E
N
max.
40 44
10.0
76
747411.02 897857.98
1337 64 90
15 04 05 19 04 05
7.1 1.5 5.1
Permeability testing
Test section, m
Lugeon
Coefficient of permeability k |m/s]
18-25
30.0
21.7-31
19.0
30-40
3,2
2.5E-06
1.7E-O6
3,5E-07
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 16.17, 30 14, 36.31 168
Test results and petrographic descriptions are shown in Annex 4EV
-r
E. - .
COMPLETED 19*044)5
STARTED 15.'04 05
Mcor.Loo CM-rtrMOWR Site: B«ro2
I- Dnlinoe B2C1 □rientaio*'
Tola< * e^gth
Inclination
This Pape i.oo-aaw Elevation '«
] Joint Surface VM VeryrMX* Fl Homb^
1:/ti Smooth
r V**y in«oFi
•a* ONq r-rlt
f
DEGREE OF JOINTING
Mo o* natural
pints Run
RQD[%!
c.     g
t
—2
o        a>
w1? c
2
8 in 7
Water Loss
Iufleor
;       n rw
Remarks
(L enology Weathering degree
Strength etc)
-------------------- --------------------
IBARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B2D-1
Borehole information
Total length, m
Casing length, m
Hole size, mm
40.44
100
76
Coordinates
E
747411 02
N
897857 98
Elevation, m asl
1337.64
Plunge / azimuth, 0
90
Starting date
15.04 05
Completion date
19 04.05
Soil overburden thickness, m
71
Depth to ground waler table . m
min
1.5
max
5.1
Permeability testing
Test section, m
18-25
21.7-31
30-40
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Lugeon
30.0
19,0
3.2
Coefficient of permeability k [m/s]
2.5E-06
1.7E-06
3.5E-07
Sample depth, m 16 17; 30.14; 36.31. 16.8
Test results and petrographic descriptions are shown in Annex 4ESTARTED 15/0*05
COMPLETED 19 04.D5
SoilTrock type
W °” Log *
c
ClKfjf    MOWR Sils: BaroJ
L On noie ^P1 Oienaicn
' Total Le^gir «jM» Inomalkr T*.a Pape I^M-F^alor 9
DEGREE OF JOiHDMG
Water
KemaAs
M
Loss
|L4holOQV,
No  ol  nalira
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r
jOintw'Ru*
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?12
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121
271
on
77 4
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-
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100
3 00
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v r,or a
STARTED ■ 15/0*05
Client: MOWR Core Log s^e; Baro2
Dnimolt WC? Ononlation Total Lonflth «-4*» md.™ikxi
1 h* P*ge»R^*<* ’
Joint    Surface VR Verr-jugl-
R Ro-qt
jrocr
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DEGREE of JOINTlMG
No  of  n»tura‘
jointv'Run
RQO(%:
Water
Loss
21
22
t—24
25
26BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B2D-2
Borehole information
Total length, m
Casing length, m
Hole size, mm
39.94
90
76
Coordinates 
Elevation, m asl
Plunge / azimuth. °
Starting date
Completion date
Soil overburden thickness, m
E
N
Depth  to  ground  waler  table  ,  m  mm max
747379 02
897949 05
1320.55
90 20 04 05 25.04 05
71
2.05 16.35
Permeability testing
Test section, m
Lugeon
Coefficient of permeability k [m/s]
0.7 -7,5
Falling Head test
12-20
21-30
30-40
Falling Head test
0.5
0.1
2.5E-07
3.5E-07
7.0E-08
1.0E-08
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 20 33. 36.0
Test results and petrographic descriptions are shown in Annex 4E.STARTED: 70**0405
COMPLEI ED: 25^04 05
Loy
Client:  MOWR Srtp  Baro2
Oriental or Incftnalon f*
Jo»rrt Surface
VR Very -TMjr
|R
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niUltf rfW.
V"
• E evation iflTi—f  ' O No IcirtH DEGREE OF JOINTING
No. ol natvrai
iOinn-'Ru
ROD'S-
2JB
■AM
s     Water
8         Loss «
©      I. >^jeo«
Remarks
(Llhotogy.
Weal*ior»^Q degree.
Strength etc)
1 10
- 100
‘••rtrtUI Brc,
W»1« Qf«| Vi IqM y*y
(AWN BvTSEGAYEMfKURIA
Isheet 2 of!
s rAR TE D: ?0'04'05
COMPLE T ED 25 <M 05________
Soil/rock type
Client MOWR
Core Log 5||#, Bafo2
Drillhole mm                   Orientate" iTQtti i ongih MMr inchnalion »r
This Page iMMUS^levaio*’
Joint Surface
VA Vary rtxiflh
R RuuUh
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DEGREE Of JOINTING
No o< natural
tools/Run
ROO(%]
ID      7Q 0               50           «       VH      V5m
8 ft -
f &s
5?t
*
„_____ — Remarks
(Litre ogy. Weatherirg degree
St’englh etci
Cr»*n ear* ?reer !«■»< yaln arr*’t>c '>e
,
nar^aeled Ch OuKU-
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LOGGED BY AB/YE TAF FESSE
DRAWN BY TSEGAYE MEKURIA
tv.BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information ~ Borehole No. B2D-3
Borehole information
Total length, m
Casing length, m
Hole size, mm
Coordinates
Elevation, m asl.
Plunge / azimuth. 0
Starting dale
Completion date
Soil overburden thickness m
E
N
Depth to ground water table , m          min max
409 6.4
76
7473483 898196 1
1307.7
90
19.04.05 06 05 05
6.1
06
8.1
Permeability testing
Test section, m
3.0-6,1
10-22
20-31
30-41
Laboratory testing
Uniaxial compressive strength Pehographic thin section analysis
Lugeon
Falling Head test 0.2
0.0 0.0
Coefficient of permeability k [m/s]
5.OE-O8
2.7E-08
1.0E-09
O.OE+OO
Sample depth, m 8.5; 34 8
8.8
Test results and petrographic descriptions are shown in Annex 4ESHEET 1 O 2
STARTED: 1WW05
Client       MOWR Silo: Bero2
Orterfaiion --
*r»" |r»» Be
Total Lenglh
Thi Page Eigvatp/- =**<
Indention XT
Joint Surlace v R v*-y tOuflT R Rough
.y- Srvxltt*
75* V«*v tircoFi llONa C**TS
§
COMPLETED. 06.0S06 Zone*
Sotl/roch type
8
xrf a"«iM
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frjM
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DEGREE OE JOINTIMG
No     010010''*
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Romanis
tl flhq logy
Wcanerirp degree,
Strength etc}
hqdj%;
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t along
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Dnll Lengll* Core recovery(%)
—I
_
Tested seel cmIBARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B2D-4
Borehole information
Total length, m
Casing length, m
Hole size, mm Coordinates 
E
N
30.6 2.6
76
747126 5
8964288
Elevation, m asl
Plunge / azimuth. 0
1315.7
90
Starting date
09.05.05
Completion date
11.05 05
Soil overburden thickness, m
Depth to ground water table , m min
2.5
2.5
max
103
Permeability testing
Test section, m 0.5 - 2,5
7-16
Lugeon
Falling Head lest 0.0
Coefficient of permeability k [m/s] 5.0E-07
5.0E-09
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth m 6 75; 24 9
Test results and petrographic descriptions are shown in Annex 4E.SHI ET 1 OF 2
completed
11
STAR TEO O9''CSA35
Cor. log CltOfll MOWN SrtaBxo?
O-inole WO*               OitflUtion Total tengib m®e Ignition
Zone*
ScMlrocii type
or-
TnitPage
Elevation a
Joint Sud.ce
/s vwv •aucr
n hojot
s-9-wr
,V Vw> wrooth (OAia.ortU
DEGREE Of JOINTING
NO  of  natural |O»nts/Run
Water
Loss
Wealhe^g degree Strength de)
ROOT*!
and pink co>-»* j' sn quart/
lpk5KJ3c gr*n» •* low net*
F«me X* ord wf-te quart/
(CO»fW
20
^ D0v*StGAV?MEKURIASHEET 2 Of 2
STARTED: ’905.05
COMPLETED V.'0S05
Soll/rocfc tyP*
, Client MOWR
Joint Su
rface Zon®e
CortLo°
Site. Baro2
VW Vt'f r>u
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Crushed
.^'7.
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DEGREE OF JOINTING
No   ol   naiu’al
joints'Rur
ONo o*its
Water
Loss
Remarks
(LWKW
Weather ng degree Strength etc)
o io xi :<
ROD[%)
M3 IOC V® VS*
logged BY abiye tahesse DRAWN AY TSEGAYF MEKURIABARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B2T-1 Borehole information
Total length, m
Casing length, m
Hole size mm Coordinates
Elevation, m asl.
Plunge / azimuth, °
E
59 9
127
76
745879.0
N                             899983 9 1307.3
90
Starting date
20.05.05
Completion date
27.0505
Soil overburden thickness, m
11.0
Depth to ground water table m
min.
0
max.
0.5
Permeability testing
Test section, m
20-32
Lugeon
15,0
Coefficient of permeability k |m/s]
2.1E-06
32-41
17.0
42-48
30,0
47-60
35,0
2.5E-06
3.7E-06
5.5E-06
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 21.4, 36.2
230
Test results and petrographic descriptions are shown in Annex 4E.STARTED 200505
Chert       MOWR
5iU B«ro2
Drcnoe jni Ohontrtcr
Folal Length »J8m inclination This Page ajMeje^Eicvalic-'
DEGREE OF JOtWTIMC
Na  ol  natural jor'11 Ruh
Joint Surface
»<*v •cvg*’ M Hevo*
Srn Sr-cnP’ VSir »4fy inoc*1
IllHOjDCta
COMPLETED 27/OS’Ob__________________ Sort/rock type
- inc • l
r iflkluuac
mm
Water
Loss
Remarks
(Lithology,
Weathering degree,
Strength etc)
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DEGREE Of JOINTING No of 'la1u al
0 Nr c-m
r
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Loss
<5
L
5
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I
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8
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T^rT^r-BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B2T-2
Borehole information
Total length, m
Casing length, m
Hole size, mm Coordinates
E
N
100 85 27.0
76 745102.2
900838.5
Elevation, m asl
1303.5
Plunge I azimuth. 0
60/0
Starting dale
29.0305
Completion date
10 04 05
Soil overburden thickness, m
9.0
Depth to ground water table . m          min max.
Permeability testing
0.0
0.5
Test section, m
Lugeon
Coefficient of permeability k [m/s]
41-61
0.1
60-71
0.3
72-82
4.0
78-92
1.6
90-101
0.7
2.2E-08
4.7E-08
6.0E-07
2.5E-07
1.1E-07
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 72 0, 97.7
72.0, 97 7
Test results and petrographic descriptions are shown in Annex 4ESTARTED 29/02/05
W or. Loa           Client MOWR Site: 0aro2
J Dniinoio un Cktonlaion &»r tfai Length ’MMg ndinatkr ir
I ’M Page MMMfcgFlMtinn <—
COMPLETED: 1004-05
SHEET 1 OF 5
Joint Surface IVR Vary rwqt
A Hougr Sm StroofT
VS** Vwyira* C Nr iwn
Soil/rock type
f .llUtJ rtf'
T
DEGREE OF JOINTING
to    qI   natural
jointsRun
Water
Loss
RQD|%)
• or
Remarks
(Lrtboiogy. Weaihecing degree
Slrunoih olc)STARTED 29/02/05
Core log C’"m M°WR
Sito: Baro2
I
I Dr'.Phoie wn Orentator iht
COMPLETED 10.*04*05
SHEET2O<:5
I
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l Ths Pago iumiw levahon <— *1
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,YR Vuryjoo^)
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COO
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1 1 1r I
DEGREE OF JOINTING
No o< naiura.
lOinls/Run
§
<3
t
i—
|5
-
1*
1C
o
| "5
8.2 5
IC N
£c
£
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c
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□
m •   s •   s
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Loss
ROOpq
Remarks
(Llfho'ogy. Weathering degree
Strength etc)
L
0 w ?C 0 v inr> 1
8  p
2  *
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1 98
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4
Li ? __
_______ _J00 ICOMPLETED; 10 0<t>5
STARTED Sli.'DZ-'OS
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5rt»: B.I02
Drillhole irn Oncniaton
Tola I L<r>gih lapis Inclination tr
This Page ao flMtjo |= iqvaion ww* »<J degree OF JONT1NG
Na.  □!  natural
jotnlSi'Rur*
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j l il ho logy, Wealhering degree.
Sliartnlh etc)SHEET * OF*
STARTED 2S'020S
.              Chant MOWN
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Ollnole im OritntUcn IMT Total Length na.—* Inclination ar This Page WK*fievarior Mm
DEGREE OF JOINTING No □! natural
COMPIETFD 100405
Joint Surface
vr
h Muugn
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' V5f VTVCtl
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RQOI%1
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degree of JOINTING
Ho of naiuraJ
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RQC(%;
Water
Loss
Renarks
^UhO'ogy, Wealhenng degree.
SVengflh etcl
I.
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tv •» ‘-*Ft *BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B2T-3
Borehole information
Total length, m
60 0
Casing length, m
46 2
Hole size, mm
76
Coordinates 
Elevation, m asl
E
N
743928.9 9020536
1358.7
Plunge / azimuth. 0
Starting date
90
29.05.05
Completion date
01 06 05
Soil overburden thickness, m
Depth to ground water table . m min.
40.5
5.0
max
10.0
Permeability testing
Test section, m 25-34
36-46
Lugeon
Falling Head lest 15,0
Coefficient of permeability k [m/s] 5.6E-08
2.0E-06
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 43.2. 58.1
Test results and petrographic descriptions are shown in Annex 4ECOMPLETED 010605
SHEET 1 Of 3
STARTED: 29/DS'O5
Client* MOWR
Site 0aro2
Drillhole MD Orirwcn
Tola   Length   ■*"   Inc&nenon   ir This Page »»» «"»E levalton g^iel
DEGREE OF JOINTING
No of natural
pdS/Rir
RQO(%j
SotVfock type
Joint SurfKt
R Aou«r Sr Snort
Zonn
FAedOTl
C.-u»r*J
£
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cF
5
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Loss
-J               §
?
5
®
Renarks
i trilogy. Weatnenng degree.
Strength etc)
z.
Q
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Lagfort
J
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“to w'»
50 ,ocSHEET 2 OFJ
STARTED 29*05/05
COMPl E TE D 91 •Ofc‘05
Client: MOWR
Cort Log s||< Bjf02
Drii.’xjle wti
Total Longfh
This Page
Zone*
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_______ iod rock tyP* WL .’J uoi*
Ml
Me
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Inclination
Nation tf
j4
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degree of jointing
No   al   natural
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RQD(%]
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kv>- 1             ,BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B2T-4
Borehole information
Total length, m
Casing length, m
Hole size, mm
Coordinates 
E N
Elevation, m asl
Plunge I azimuth. °
Starting date
Completion date
Soil overburden thickness, m Depth to ground water table , m min
max.
251 0
35.0
76
742837.5 902179 0
1316 9
90 ? ?
4.7 6.0
22.5
Permeability testing
Test section, m
Lugeon
100-120
2.8
120- 149
3.0
150-170
2.2
170-192
1.7
191 -211
3.4
212-230
0.9
229 - 242
0.3
241 - 250
0.7
Coefficient of permeability k [m/s]
3.4E-O7
4.0E-07
2.9E-07
2.3E-07
4.3E-07
1.2E-07
3.8E-08
8.6E-08
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m
8 8, 24.3, 32.4, 98 2. 149.5, 207 2 9 0. 24 4.210.0
Test results and petrographic descriptions are shown in Annex 4ESTARTED 2905-05
1 fCoca Log
Client          MOWR SIU: 0>ro2
Dfllinoa ayn Orientation
ToW Length at Hr Inc^aton
This Paoe MMM«mE=evat<>H
DEGREE OF JOINT)MG
No ofnilu*a
lOTttRur
RQOf%]
Rerrark*
(L.thoogy.
Wrainei’-oQ rte^'ee
Strength etc]
rF'JLgougo valeral
Zones
♦        ♦        +       4-       +       +        +        +       4*                +       4        +       4.4.< ♦        •        ♦        ♦•44'                      —      4*4-r44*4*4444-e
+        -***44*4-e4*4-*«4-*4»**4-
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8
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8
8
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8
8
8
□»i|i Length
Core recovery;%)
■——
Tested secliors
fi » ’ s
3 * d 
“5 if?
COMPLFTED Q1W0SCOMPLETED Qi 0605
SHEET 3OF U
STARTED 29/05*05
Jolnt SufFiC#
Zor«
Soili’fCMzfc. h*F*
C    nt MOWR
tori Log  ’"
Srta Sard
VH Vwvrrn'tf'
n flnuafi
k Dnlihoie wr<                       Oncnlario^
in SrrwU'
Tolll length 
IncFnalon 9T
VSn ‘^iHY smin-f1
BCD
TFW_J
TH$ Page <IMMfcE eval-on
p—
OEGREE OF JOINTING
No.    cl    r-alLraf
jointi Au«-
r
Water
Loss
Remarks iLrtnotagx
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STARTED 29W05
COMPLETED 01 0605
—SoiVrocVTyp.
_        ,             Client MOWR
C<KwL°«              Sit. Baro2
Dnlihoie wr<                  Orientation
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Drillhole HU                Oriental on Torn       LrdlimiNi       Incfrnaton       £ This Page BMWOF •vaicm
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—SHEET 6 of ’3
STARTEO: 29/05/05
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Joint Surface Zonos
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STARTED 29.‘05-^
Client   MOWN
S«e Bmo2 Chthofc BJT4         Ore'-tal'O^ Total Length              ncanation •* TM Page 1MMW* ‘evahOH
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a *W
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I IU-1
Mr
— MM
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Romans
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DEGREE OF JOINTING
Wealh«r^0 A‘9'p*’
svmgth etc)
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joints'Run
RGOf%]
-205
L2O6
F2O7
"215
'214
215
U217
218
.219
E
A
n Ty t^STARTED 29.'OS.'O5
Client: MOWR Core Log 5^ Baro2
Drillhole           «n<           Onenwcn Total Lengr py* IncSnaHo"
iCJiai Lenv'e== ’-------------------------------------
This Page
COMPLETED 01 0&05__________ _____ __ Soll/roc* type
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degree of JOINTING
Loss
(L4ho»W.
Weathering dogt*0
Strength etc)
No. ot natural
joint* Run
ROD(%]
---- ---------- *
Cnarte yam da** grat
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character ./abon <s conrcr
224
225
£230
231
232
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£237
238 239
240
I OGGED 0Y ABIYE ^AFFhSSfQlA
prawn hytsegayemfkuriaSHEET 13 OF 13
STARTED:
core Log CM-nt M0WR
Srte: Baro2
| Ctiliixile                     O^rtaton Total Lanamaaaaw incfcnalon
TM PageDMMmjfcEievalor ••*■**! DEGREE OF JCMMTIWG
No  o<  natural
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Water
Loss
Ramarks
(Mbototjy
Weathering degree.
Sutmgih etc)
RQD|%] |
255
256
BY TSEGAYE MEKURIABARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B2T-5
Borehole information
Total length, m
Casing length, m
Hole size, mm
Coordinates 
E N
Elevation, m asl
Plunge / azimuth, 0
Starting date
Completion date
Soil overburden thickness, m Depth to ground water table . m min
max
200.3 9.4
76
739772.6 9030557
1200 2
90 05.06.05
19.0605 6.7 5.0
100
Permeability testing
Test section, m
79-101
Lugeon
1.2
110-130
0.6
130-150
0.5
151 - 172
0.3
170-181
0.3
181 - 192
0.7
190 - 200
1.2
Coefficient of permeability k [m/s]
1.5E-07
7.6E-08
6.8E-08
3.9E-08
3.9E-08
9.0E-08
1.7E-07
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 84 0.141,2.181 0 85.0. 185 0
Test results and petrographic descriptions are shown in Annex 4ESTARTED 05.-050f>
tor. Loa
*°WR * Site: BaroJ
Drillhole Bm Orientation
TdUI >.9(101* MajBiw Inciiralion BT Thii Pago B aaaB.90* F evalion •«*•**!
Joint        SuHace VR Vf’V'Ou?*
h Hover
Sir SmooT-
i/5«n v«f> v-x^- r I O No pnl*
COMPLE TED: 19'06^5______
Zo^s
TdVrocktype
SHEET 1 OF 10
H
l'IHd pH
£
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DEGREE OF JOINTING
No    ol    natural
|oints.Run
RQOt%|
5
! I
h
;i
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?
0
-J
X Q^5
l
s
Water
Loss
•§ 8
8
5
•
»-    lugaon 3J
Remarks
(Lrtho«ogy. Weathering deg'P*
Strength ale)
____ _ _________ —-----------
ig “ ad o
•xjSHEET 2 OF 10
STARTED: 05/06/05
„        , Client MOWR
Coro Log
B«ro2
COMPLETED 19*06/05
Zonal
Drillholo
Orientation -
F.n«d io"'
??
f
Tniai   t   pngihwojow   inclination   wr This Pago W.W Avalon maaa4
DEGREE OF JOINTING
No. o( natural
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400
__ ———-------
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RQD(%]
6•
6
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Rerrarks
(Lithology.
Weathorrng degree
Strength etc)
0 IQ 20 o                                          50              100 VR VSm
2
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100
/
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SHEET 3 OF 10
STARTED: 05/0605
"cor. L&n Cll*nt **0Wfl
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»* Drillhole ifli Orientation
COMPLETED: ig.06.D5__________________ _ Soil/rcck typ*
Total length
Inc^narton
Joint Surtax* VP
tJrt fimenr r VEm W*V srrr *■
tetri
irt
st no
This Page 4®JMMf!!£iovatxxi m
DEGREE OF JOINTING
Nd     til    nalL'U
Water
Loss
Remarks
ILJthotogy.
Weatherng degree
Slrti^flth flicJ
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LQg Site: Baro2
•     Driiinote     tm      Oncntation 'Total                LengthIndication {This Page MH WJteCtevation
SHEET 4 OF 10
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Ni i erf natural jolnlfr Rm n
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COMPLETED 190605 Zones
F—F ’t®(1 Km*’’
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DEGREE OF JOINTING
Water
Loss
Remarks
(Lithology,
Weathering degree
No ot natural
jOinis/RLn
—
Strength eic)
RQO[%l |
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DEGREE OF JCHMTING
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RQO(%J
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Loss
Ramarks
jUhotofly.
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STARTED. 05A)S‘05
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Drillhole ttn               Orientation
COMPLETED 190605
Joint Surface
Zones
Soil/rock type
VR Very nxij/i
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w^rlefl
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DrortHjf^r-
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Total Length
This Page
Intknalioci
I  Hl  VSm
rti
Qoniu
lev anon
'•b*jai or*
DEGREE OF JOINTING
No olnatura.
£ Jo^tVRun
RQDl%i
? Water Loss
Remarks
(Lithology,
Weathering degree,
Strength etc)
1
in ‘ r«
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154
4 55
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DRAWN BY IStGAYE MfcKUH'ASTAP TED: 05.0605
COMPLETED; 19/0605
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Site Baro2
On Uhde mt>               OrtoUbon
Total     LengthBMSm     lncSr«i»on     »r
Tht Page                             legation ffl-wt
DEGREE OF JOINTING
Mo  of  natural
X*
?’ s            8          ?
Water
Loss
Remarks
(Lflhotogy,
V
-J
Weathering degree
K>nt*iRun
Strength etc)
roo<%;
I?
IX
"
£s
•
•
162
-----
• >-
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170
171
173 174
£4 75
Txsftj ihifbm
178 b! 79
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—-«=e--------------- -...---------/I
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* .....BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. B2T-6
Borehole information
Total length, m
Casing length, m
Hole size, mm
100.7
182
76
Coordinates 
E
N
737602 4
9030039
Elevation, m asl.
1089 2
Plunge / azimuth, °
90
Starting date
1804  05
Completion date
21.04.05
Soil overburden thickness, m
Depth to ground waler table . m min
max
10.4 7.4
50.2
Permeability testing
Test section, m
Lugeon
Coefficient of permeability k [m/s]
50-70
1.0
70-80
0,0
80-90
0.0
90-101
0.0
7.7E-08
0.0E+00
0.0E+O0
0.0E+0O
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m
387
39.0, 96 0
Test results and petrographic descriptions are shown in Annex 4E.COMPLETED: 07.0405
SHEET 1 Of 5
STARTED 1804 05
Cor* log Cll.nl MOW"
5oVrock type
Zo^«>
Site: Bero2
Dnllhoe in
Oenlilo"
Total Length lit
mc^nat©*"
-a nwdpr"
I •x”r’*d
3 C’-J*-’’*1
Tris Pipe MN»>«F levalor tat OEGREE OF JOINTING
No of natural
Klints Run
PODI%1
joint SuWice vR vem •^uQr P Rcvflf
5ff. SfRocr
/s- van imoon o MO cwt*
Water
Loss
Remarks (Lihology.
Weaitx’iiX) (5c9rec Strength elc)
-M VfirfT
S*0Mv wriT'Crcc XJn* to Qran, <f*>w jreer-'
titeihmf i-noh boeic itxs
I 0Y ABIYE TAFFESSE N tjv tSEGAYE MEKURIASTARTED. 18/04/05
COMPLETED: 0204 05
SHEET 2 OF 5
Core Loo CMint hA0WR
Site: Baro2
’DnMhote am            Ofientalion
t Total Length
inclination
T hi$ Page » W RM Ovation *
DEGREE OF JOINTING
Ho   ol   natural
Wrls/Run
RQD(%]
50 idd
Joint Surface
• Very rough
r
'Srr Smootr lv$»r Very wof
- O No jonh,
SoiUrock type
I>r1x/O»r
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frapait frcl* >j«fV ’••3MB*
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5 Loss
N8
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=
8
S
H L^gecr
Remarks
(Uhology
Weathering degree
Strength etc)
' 21
.22
I 23
r»
I 25
LOGGED  by  AHI  YE  1AFFESSE DRAWN BY TSLGAYE MEKHRIAiSTARTED 1*04.05
SHEET 4 Of 5
COMPLETED'02 C4.05
Core Log Client *OWR
Site: Baro2
Drillhole am Orkontalor
Total Length t—e— inclination
T1h1 »nss Page toe*—IW^'cvalron imwnl DEGREE OF JOINTING
No    o’    natu'al ioin(s.'Run
Joint Surface VH Ver j- rough
H Paugh
tx- iiroor
•’S^' Ve*v prut-fi DNOfCXS
Zone*
R -ll»d pr-!
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□ Crutted
Scxl/rock typ®
Ch«OU-fl*-
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Water
Loss
Rprna’ks
iL^otogy
Weathe’-ng degree
Strength etc-
r-72
(    OGGEO    BY    ABlYE    TAFFESSL DRAWN BY TSEGAYE MEKURIASHEET 5 OF -
STARTED 1B04 05
i —       CM**: MOWR O,,L°B Srt. turc.2
Dr I foie tt* O* entat>or-
COMPLETED 02/0*’05_____________________ 5otl/rocfc type
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9 n«U
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I •’•              %on
JJ
Total I
TM Pape
Irchratlo*'
avatlon s
DEGREE OF JOINTING
X
T
No   of   natural                                               3
fOr^la.'Rc'-
*E
H
i
xi
t
RQOTM
ta « C 50 10°
C
$
/
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Loss
Remarks
(l nhologv.
Weal herdep'eo.
SVengin etc)
o
C
s
*
3J
i^-jaon
—T-----------------•#------------ W
-----------------------------------------------
’VST-
1ULUBARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. GJD-1
Borehole information
Total length, m
40.1
Casing length, m
3.6
Hole size, mm
76
Coordinates
Elevation, m asl. Plunge 1 azimuth, 0
Starting date
E
N
744844.7
897190.8
1201.8
90
26.04.05
Completion date
02 0505
Soil overburden thickness, m
2.9
Depth to ground water table . m
min.
1.2
max
98
Permeability testing
Test section, m
3,5 -5
10-25
20 -34
30-40
Laboratory testing
Lugeon
Falling Head test
0.0
0.0
0.0
Coefficient of permeability k [m/s] 2.4E-07
5.0E-10 O.OE+OO O.OE-OO
Sample depth, m
Uniaxial compressive strength
8 9. 32.6
Petrographic thin section analysis
10.0
Test results and petrographic descriptions are shown in Annex 4ECOMPLETED; 02/05/05
STARTFD 264W05
SoiMrock type
Cor» Log
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,              Client MOWR Cor*Lc*                  Site. Genji
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DEGREE OF JOINTING
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4** *BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. GJD-3
Borehole information
Total length, m
Casing length, m
Hole size, mm
41.1
5.8
76
Coordinates 
Elevation, m asl
Plunge I azimuth. °
Starting date
Completion date
Soil overburden thickness, m Depth to ground water table . m min
E
N
744722.8 8971789
1204 9
90
02.05.05
03.05.05
4.9
max,
Permeability testing
Test section, m
Lugeon
Coefficient of permeability k [m/s]
3-5,8
10-22
22-31
31-41
Falling Head lest.
2.2
0.0
0.0
2.6E-07
2.6E-07
O.OE+OO
O.OE+OO
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Sample depth, m 8 8, 9 1.28.0
9.3
Test results and petrographic descriptions are shown in Annex 4E.COMPLETED 0XDSO5
SHEET 1 OF 2
STAHTED 0*05/05
j^C<*• Log
Client MOWR
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Dr.’ihoie ojqj Orientation
Tot> Length nw Inclination
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------ --
«------------- TM
------------------ -------------------BARO MULTIPURPOSE PROJECT - FEASIBILITY STUDY
EXPLORATORY CORE DRILLINGS
General information - Borehole No. GJT-1 Borehole information
Total length, m
Casing length, m
Hole size, mm
Coordinates
Elevation, m asl
Plunge f azimuth. °
Starting date
Completion date
Soil overburden thickness, m
E
N
Depth to ground water table . m       mm max
Permeability testing
100.4 10.3
76
745084 9 898392.0
1232.6
90
26.04.05 30.04.05
9.0
0
7.4
Test section, m
Lugeon
50-71
0.0
70-82
0.1
80-91
0.2
91 - 100
0.3
Laboratory testing
Uniaxial compressive strength Petrographic thin section analysis
Coefficient of permeability k |m/s| 1.3E-09
1.3E-08
2.6E-08
4.7E-08
Sample depth, m
36.3. 39.1,42.5. 73.5. 73.8, 93.6
938
Test results and petrographic descriptions are shown in Annex 4ECOMPLETED: 3O.WJ5
SHEET 1 OF 5
i;
I
STARTED: 264M5
Cllenl MOWR
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COMPLETED 30/04/05
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Summery

Summary of Baro Multipurpose Project Feasibility Study - Geology and Geotechnics

Project Overview

The Baro Multipurpose Project consists of three hydropower schemes in Ethiopia:

Baro 1: Upstream plant with 200m gross head, 3.5km waterways
Baro 2: Downstream plant with 510m gross head, 12.7km waterways
Genji Diversion: Tributary scheme with 390m gross head, 5.9km waterways

Geological Setting

The project areas are underlain by Precambrian crystalline basement rocks (Alghe Group) overlain by Tertiary basalt lava flows (Mekonen Basalts). Significant areas are blanketed by red lateritic soil with scattered alluvial deposits along riverbanks.

Regional Geology

The Western Ethiopia Shield where the project is located consists of:

Gneisses and migmatites at upper amphibolite metamorphic grade
Basaltic lava flows uncomfortably overlying the Precambrian basement
Vesicular basalt with large plagioclase phenocrysts found at about 1300 masl

Site Investigations

Comprehensive investigations were conducted including:

Core Drilling Program

Project Area	Number of Boreholes	Total Length Drilled (m)
Baro 1 Dam Site	7	381.8
Baro 1 Tunnels	6	558.2
Baro 2 Dam Site	4	151.9
Baro 2 Tunnels	6	772.7
Genji Dam Site	2	81.2
Genji Tunnel	1	100.4
Total	26	2046.2

Key Findings from Investigations

Soil Conditions

Baro 1: Soil thickness varies from 4m to 51m (residual soil from gneiss/basalt)
Baro 2: Right bank has thin soil (0-6m), left bank has thicker cover (13-16m)
Genji: Modest soil cover (0-6m) with rock exposed in riverbed

Rock Quality (RQD)

Rock Quality Designation classification:

Baro 1 Dam: Highly variable - from 0% High/Very High in B1D-4 to 77-83% in B1D-1/-7
Baro 1 Tunnels: Generally good - 80-98% High/Very High in most boreholes
Baro 2/Genji: Generally high quality - >90% High/Very High in most dam site boreholes

Rock Strength (UCS)

Project Area	Low Strength (%)	Medium Strength (%)	High Strength (%)	Very High Strength (%)
Baro 1	0	56	44	0
Baro 2/Genji	8	34	58	0

Permeability

Generally low to very low permeability, with higher values in jointed zones at dam abutments requiring grouting.

Groundwater

Water table depths vary significantly (5-28m at Baro 1, 8-23m at Baro 2) with seasonal variations expected.

Engineering Recommendations

Dam Foundations

Baro 1: Combination dam recommended:

Concrete spillway in narrow gorge on competent bedrock
Main CFRD across main valley (partly founded on firm residual soil)
Saddle dams as clay core embankments

Baro 2:

Concrete spillway and intake at right riverbank
Clay core rockfill dams on both sides
Special measures needed for high permeability layer on left bank

Genji: Massive concrete dam recommended due to favorable foundation conditions.

Tunneling Conditions

Precambrian basement rocks are suitable for tunnel construction with sufficient quality for self-supporting openings. Recommended support measures include:

Rock bolting with steel fiber reinforced sprayed concrete in general
Heavier structural support (reinforced sprayed concrete arches or cast lining) in weakness zones
Cement grouting for leakage zones

Construction Materials

Gneiss rock suitable for concrete aggregates and rockfill
Natural sand/gravel scarce - crushed rock recommended for concrete and filters
No Alkali-Silica Reactivity detected with local cement

Conclusions

The geological and geotechnical investigations demonstrate the technical feasibility of the Baro Multipurpose Project. The Pre-cambrian basement rocks provide suitable conditions for dam foundations and tunneling, though with some variability in rock quality requiring appropriate engineering solutions.

Key Recommendations:

Seismic refraction profiling should be conducted during detailed design phase
Additional test pits needed on left banks (couldn't be excavated due to weather)
Rock stress measurements required for detailed powerhouse cavern design