GEOTECHNICAL BASELINE REPORTONNAM N

GEOTECHNICAL BASELINE REPORT
ON
NAM NGIEP 1HYDROELECTRIC PROHCT

















December l3th 2012


























Business Outline 1
1.1 Project Background ..„......,.........,..........,........,.,.,.„„.......,..............„.............„ ..,. I
1.2 Project Development.........„.....,......,...........,....,...,...,...............................................................,.. 1
Project Description. 2
Project Location. 3
Project Features 3
1.4 Summary ..,..............,...,.,....,....„,..,..„........,.....................................................„ .....,..,...,...,. 8
1.4.1 Mam Dam Site.,..................................................................................................,. 8
1.4.2 Re-regulation Dam 9
1.4.3 Qumry Site.„..„.........................................................................,.,..........,.,...„..,. 10
2. Existing Data on Geological Survey. 11
2.1 Previous Investigation Works..................................................,. 11
2.2 Investigation Works in 2007 and 2009........,. 11
2.3 Investigation works from 2010 to 2011..,...........,...................................,....,. 13
3. Regional Topography and Geology. 16
3. I Regional Topography .....,.,..,.....,.................„...,.,..,. 16
3.1.1 Outline of Topography.....,.................................,...,.......,...............,......................,...,.. 16
3.1.2 Development of Gorge ....,.,...„.,........................,...,.......................,. 16
3.2 Regional Geology. 19
3.2.1 Orogeny in Indochina..................,...............„....................,...........,............................, 19
3.2.2 Geologic Outline of Laos .,............,....,....,.,.,..„ .,....,...,. 19
3.4 Folded zone 20
3.4.1 Formation of folded zone .................................................................................,. 20
3.5 seismici 22
4. Geological Conditions on Main Dam Site 24
4.1 Topography ..,...,...........,..............................,.......................................,................................,..„24
4.2 Stratification. 24
Geotechnical Conditions on Main Dam Site. 25
5.1 Weathering .........................................................................................,. 25
27
Figure 5.1-2 The Distribution as trucks of dissolved lime .......,.......................,........,....„...,.......,...27
5.2 Rock Classifications and their Mechanical Properties...........,...............,...,........................,. 28
5.3 Discontinuous Planes .............,........,.........,...........,...............„„.....,. 29
5.4 Shearing Strength and Modulus Deformation. 29
5.5 Permeability of Rocks and Groundwater Level..................................................,.......,.....,. 30



6.





















9.



























12.

Quarry. 31
6.1 Outline of Investigation Works ..„...,.............................................................,............,..,. 31
6.2 Outline of Topography and Geology..............................................,..........,.........,.„...,.„....„,. 32
6.3 Weathering and Quality of Rock............„,.,..,....,..,.,.....,.,...,............,.„,.„...„,.......,........,....,. 33
Powerhouse 34
7.1 Topography and Geology............,.......,.,.„..„...„...,..„.,.,.......„,.......................,. 34
7.2 Geotechnical Key Point........................................................................................,. 34
Diversion 35
8.1 Topography and Geology...„.....,...........,..,..,......,......,.........,.....................................,...........,...35
8.2 Geotechnical Key Point......,....„.„...„..,.....,..,.....,................,...................................,............,..,.35
Reservoir. 36
9.1 Slope Condition for Surrounding Area...................,........,..,..........,............,....„,......,....,..,. 36
9.2 Sedimentation.....................,........,..................,.,..........,.......,...„.,.,........,.........................,. 38
Re-Regulation Dam. 39
10.1 Outline of Geological Investigation Works. 39
10.2 Outline of Topography and Geology..............................,.....................................,. 39
10.2. 1 Topography......................,......„,....,.........,....,........................,.................,............,. 39
10.2.2 Geology ..........................,...........,.,..............,.,.....,..,.......,....................,........,....,..,. 40
10.3 Condition of Bedrocks ,......,..................,....,....,..,..„.............,...,. 41
Bedrocks of Saddle Dam and Embankment Materials. 42
11.1 Foundation of Saddle Dam........,.„.....,...,......,........,...,....,.........,....................,.......,...,....,. 42
11.1.1 No.I Saddle Dam................................................,............................,......,......„.........,..42
11.1.2 No.2 saddle dam ...,..........,.........................,.....................,..............,.........,. 42
11.1.3 No.3 saddle dam ...,....„..„......................,..................................,.............................,. 42
11.1.4 No.4 saddle dam ,.........,.„...,........,.......,.„.„,..,.,...,........................,........,.,. 42
11.2 Embankment Materials for Saddle Dams. 43
Access Road 44
12.1 Outline of InvestigationArea 44
12.2 B.Nonsomboun - B.Hat Gniun......................,..,.........................,..,...........„.,............,.,.,. 44
12.3 B.Hat Gniun - Main Dam Site.....,.,.............,.............,...„..„....................,. 44
Geotechnical Baseline. 46
Excavation Line and topographic line........................,. 46
13.2 Rate of rock and soil.......................,...,.................,..,..........,.......,.....................................,...,...46
13.3 Geological c1assi:Creation of diversion tunnel...............................................,.,............,. 46











Appendices

1. Geological Drawings
Geological Map
Geological Cross Section
Lugeon Map


2. Raw Data on Geological Survey
Drilling Log
Drilling Core Photo
Adit Development Figure
Lugeon Record
In-situ Shearing Strength Test
Bore Hole Jacking Test 2,7 Results of laboratory test
Sketch and Photos of test pit
Seismic Wave Prospecting
Trial Excavation















































Preface

International hydropower project involve inherently substantial risk and especially, geological risk is one of the most important factor of hydropower project in which high concrete dam is constructed. The Nam Ngiep I Hydropower Project involves geological risk. In many cases, it might be difficult for contractors to bem the all of seological risk, and thus the contractor s may over estiiriate the geological risk. On the other han‹t. the developer can estimate the geological risk
properly, based on the experience and skill of precedent h)²dropower pi’oject. In order to mitigate cost overrun caused by the geological risk. price adjustment is adopted.. The Nain Ngiep 1 Hydropower Project adopts the price adjustment in accordance with the volume of foundation excax ation, concrete and rate of soil and rock, and tunnel support pattern of diversion tunnel. In order to adopt the price adjustment. the developer and the contractor should share and agree the geology of the main and i e-regulation dam and powerhouse, and diversion tunnel in advance (“Geotechnical Base1in•”).
This report provides the Geotechnical Baseline including topographic line, geology and rate of rock/soil with respect to the dam and powerhouse foundation and diversion tunnel.
This report is edited by the Kansai EJectric Power Co., Inc. and reviewed by senior geologist Mr. Kawahara and Newjec Inc.













































1.


1.1










































1.2

BUSINESS OUTLINE



PROJECT BACKGROUND


The Lao People’s Democratic Republic (Lao PDR) is blessed with hydropower potentials with abundant water resources and topography where large difference in elevation is exploitable. The country, having 26.5 GW of water-power resources has, since 40 years, developed a meager 3.5% of its developable capacity which is said to be 18 GW.
The positive promotion of hydropower that utilizes plentiful water resources and enables exportation of power mainly to Thailand and to other neighboring countries to earn foreign currencies is one of the pillar policies of the Government of the Lao PDR (GOL).

In Lao PDR, government owned Electricite du Laos (EDL) owns and operates a number of hydropower stations. With the policy of domestic and rural electrification, EDL’s primary objective is to supply power within the country, but they positively export excess power to Thailand.
In the mean time, Houay Ho Hydropower Station (150 MW) and Theun Hinboun Hydropower Station (210 MW) commenced commercial operation in 1998 and in 1999 respectively. Both power stations are owned by Independent Power Producers (IPP) through Built-Operate-Transfer (BOT) scheme and export power to Thailand. In 2009, the Nam Theun 2 Hydropower Station (1,070 MW) and Se Xet 2 Hydropower Station (76MW) started operation to export its generation energy to Thailand. Furthermore, Xekaman 3 Hydropower station also commenced operation to start commercial operation in 2010 as a energy supply project to Vietnam.

On the other hand, Thailand’s economic recovery, since the Asian Financial Crisis in 1997, has continued to advance, and according to the power demand forecast made by Electricity Generating Authority of Thailand (EGAT), annual growth through 2015 should be ox er 4.5%. In order to secure supply capacity to rrieet this power demand, Thailand has sought ways, other than domestic development of power sources, to import power from neighboring countries including Lao PDR.

While the environment for investment is impro