PREQUALIFICATION DOCUMENTS Section-2 Project Description Report

MARCH 2011

Kabeli Energy Limited Buddha Nagar, Kathmandu

Kabeli Energy Limited

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Table of Contents Page no.

1.  PROJECT COUNTRY .......................................................................... 1 1.1  Nepal in the globe ..................................................................................................................................... 1 

1.2  Access from outside ................................................................................................................................. 1 

1.2.1  By Air .............................................................................................................................................................. 1 

1.2.2  By road ........................................................................................................................................................... 1 

1.3  Infrastructure, facilities and some facts ................................................................................................ 2 

1.4  Hydropower potential of Nepal ............................................................................................................ 3 

1.5  Political system and government ............................................................................................................ 3 

1.6  Hydropower development policy, status and private sector .......................................................... 3 

2.  PROJECT BACKGROUND ................................................................. 4 2.1  Project development agreement ............................................................................................................ 4 

2.2  Kabeli Energy Limited, the Developer .................................................................................................. 4 

2.3  Power Development Fund ...................................................................................................................... 4 

3.  PROJECT STAGE ................................................................................. 5 3.1  Project identification and 1998 feasibility study ................................................................................. 5 

3.2  Updated Feasiblity Study in 2010 ........................................................................................................... 5 

3.3  Physical model study and detail design ................................................................................................. 5 

3.4  Tendering ..................................................................................................................................................... 5 

4.  FIELD INVESTIGTIONS ..................................................................... 6 4.1  General ......................................................................................................................................................... 6 

4.2  Topographical Survey ............................................................................................................................... 6 

4.3  Hydrology .................................................................................................................................................... 6 

4.3.1  Catchment physiography ........................................................................................................................... 6 

4.3.2  Drainage ......................................................................................................................................................... 6 

4.3.3  Flow measurement observations ............................................................................................................ 7 

4.3.4  Rating curve development at the Headworks and Tailrace site ..................................................... 8 

4.4  Sediment study ........................................................................................................................................... 9 

4.5  Geology of Project Area ....................................................................................................................... 10 

4.5.1  Engineering Geological Mapping ............................................................................................................ 10 

4.5.2  Geophysical Surveys ................................................................................................................................. 10 

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4.5.3  Drilling and field testing ........................................................................................................................... 10 

4.5.4  Construction material surveying and testing ...................................................................................... 10 

4.5.5  Summary of geological investigation ..................................................................................................... 11 

4.6  Environment and social condition of the project ............................................................................ 12 

4.6.1  Demographic Characteristics ................................................................................................................. 12 

4.6.2  Settlement pattern .................................................................................................................................... 12 

4.6.3  Occupation .................................................................................................................................................. 12 

4.6.4  Market/Bazaar ............................................................................................................................................ 12 

4.6.5  Water Supply .............................................................................................................................................. 13 

4.6.6  Energy Use .................................................................................................................................................. 13 

4.6.7  Transportation and Communication .................................................................................................... 13 

5.  TECHNICAL FEATURES .................................................................. 14 5.1  Project Location ...................................................................................................................................... 14 

5.2  Project Layout ......................................................................................................................................... 14 

5.3  Salient features ........................................................................................................................................ 16 

5.4  Major components ................................................................................................................................. 20 

5.4.1  Peaking reservoir ....................................................................................................................................... 20 

5.4.2  Barrage structure with gates, operating platform, intake, stilling basin and fish ladder .......... 20 

5.4.3  Underground settling basin ..................................................................................................................... 21 

5.4.4  Tunnel for diversion during construction ........................................................................................... 21 

5.4.5  Access tunnel to headrace and settling basin ..................................................................................... 21 

5.4.6  Headrace tunnel ........................................................................................................................................ 21 

5.4.7  Surge shaft ................................................................................................................................................... 22 

5.4.8  Buried penstock pipe ................................................................................................................................ 22 

5.4.9  Semi-underground powerhouse and tailrace ..................................................................................... 22 

5.4.10  Powerhouse protection structures ...................................................................................................... 23 

5.4.11  Hydromechanical components .............................................................................................................. 23 

5.4.12  Electromechanical components ............................................................................................................. 23 

5.4.13  Switch yard .................................................................................................................................................. 24 

5.4.14  Access road................................................................................................................................................. 24 

•  Access road to headworks ..................................................................................................................... 24 

•  Access road to powerhouse .................................................................................................................. 24 

5.4.15  Camp area (housing) ................................................................................................................................ 24 

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6.  CONSTRUCTION SCHEDULE AND PLANNING ....................... 25 

ANNEX

LIST OF FIGURES Page no. Figure 4-1: Kabeli catchment above the intake site ........................................................................ 7 

Figure 4-2: Rating curve for the gauging station at the intake site ................................................... 8 

Figure 4-3: Rating curve at the tailrace site ................................................................................... 8 

Figure 4-4: Mean monthly hydrograph ......................................................................................... 9 

Figure 5-1: Location of the Kabeli-A Hydroelectric Project in National Map ................................. 14 

Figure 5-2: Project layout of Kabeli-A Hydroelectric Project ....................................................... 15 

Figure 5-3: The location of the powerhouse ............................................................................... 23 

Figure 6-1: Proposed Construction Schedule for KAHEP ............................................................ 26 

LIST OF TABLES Page no. Table 4-1: Catchment characteristics ........................................................................................... 7 

Table 4-2: Flow measurement observations ................................................................................. 7 

Table 3-3: Mean monthly flows from various methods, m3/s .......................................................... 8 

Table 5-1: Salient Features of Kabeli-A Hydroelectric Project ...................................................... 16 

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1. PROJECT COUNTRY

1.1 Nepal in the globe Nepal is a sovereign and autonomous country occupying an area of 147,181 km2 in southern Asia. It lies within latitudes of 26° 12’ N to 30° 27’ N and longtitudes of 80° 04‘ E to 88° 12‘ E. Nepal is a country sandwiched between China and India. Noted for its majestic Himalayas, Nepal is very mountainous and hilly. Its shape is roughly rectangular, about 800 kilometers long and about 200 kilometers wide, and comprises a total of 147,181 square kilometers of land. Nepal is a landlocked country, surrounded by India on three sides and by China's Xizang Autonomous Region (Tibet) to the north. It is separated from Bangladesh by an approximately 15 km wide strip of India's state of West Bengal, and from Bhutan by about 90 km wide Sikkim, also an Indian state. Most of the transit facilities to Nepal from abroad are through India. The access to the sea - that is, the Bay of Bengal – is via India.

For a small country, Nepal has great physical diversity, ranging from the Tarai Plain - the northern rim of the Gangetic Plain situated at about 100 meters above sea level in the south - to the 8,848 m high Mount Everest (Sagarmatha) in the north. From the lowland Tarai belt, landforms rise in successive hill and mountain ranges, including the stupendous rampart of the towering Himalayas, ultimately reaching the Tibetan Plateau. The perennial rivers originating from the high Himalayas and the variation in height of more than 8000 m in a width of about 200 km are the indications that Nepal is a country god-gifted for hydropower potential.

1.2 Access from outside 1.2.1 By Air

The Tribhuvan International Airport in Kathmandu is Nepal’s only International Airport. The main airlines that serve Kathmandu are the Nepal Airlines, Indian Airlines, Thai International, Bangladesh Biman, China Southwest Airlines, Druk Air, Qatar Airways, PIA- Pakistan Airlines, Gulf Air, Sahara Ailrlines, Jet Air, Cosmic Air, Korean Airlines, Itihad, Silk Air, Druk air etc..

1.2.2 By road

There are many entry ports into project area by land. The entry points with Railheads from India include Mahendranagar, Dhangadhi, Nepalgunj and Bhairahawa in the west, and Birganj, Biratnagar and Kakarbhitta in the east. Biratnagar with bordering Jogbani (India) and Kakarbhita (near to Silguri, India) are the nearest railhead points. The crossing point from China is from Tibet via Kodari. Following table presents the distance of project site from major cities of Nepal. The road is under upgradation from Phidim bazar to project site rest is all weather roads. The road networks can be observed in the map below.

Place Distance from project site (KM)

Road type

1. Taplejung 25 Feeder highway, Gravel surface 2. Phidim (district

Headquarter) 55 Gravel road, upgradation (side drain

construction, metal surface) is underway 3. Ilam Bazar 122 4. Bhadrapur 213 5. Kakarbhitta 199 6. Birtamod 204 7. Biratnagar 209 Broad Gauge Railhead available with India

connecting with Seaport Kolkata (India) 8. Kathmandu (Via.

Mungling) 797

9. Silgurhi (West Bengal, India)

325 Broad Gauge Railhead available with India connecting with Seaport Kolkata (India)

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1.3 Infrastructure, facilities and some facts Out of the total, the land area is 143,351 sq km and water area is 3830 sq km.

Total length of strategic road in Nepal is more than 10,000 km. The total length of roads including unpaved and village roads is more than 20,000 km.

Nepal has limited railway connectivity. The length of the narrow gauge railway is 59 km.

Even though Nepal has only one international airport, there are 46 domestic airports. There are more than five domestic airlines and more than three helicopter service providers.

Regarding telecommunication, the web site of Nepal Telecommunications Authjority shows that there are 8 network service providers, 44 internet service providers, 3 telephone service providers and 2 cellular mobile service providers.

The major contributor to national GDP is through agriculture. The land use pattern in Nepal is about 16% of arable land. The irrigated land is about 12000 sq km.

The natural resources in Nepal include water resources, hydropower, herbs and forest products, quartz, timber, scenic beauty, small deposits of lignite, copper, cobalt, iron ore. Nepal has total renewable water resources of about 210 cu km.

Current issues on environment are deforestation (overuse of wood for fuel and lack of alternatives); contaminated water (with human and animal wastes, agricultural runoff, and industrial effluents); wildlife conservation; vehicular emissions and the snow melting of Himalayas because of global warming. Nepal has signed different international agreements on environment. These include

PROJECT AREA

INDIA (Sikkim)

INDIA

(West Bengal)

INDIA

(Bihar)

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Biodiversity, Climate Change, Climate Change-Kyoto Protocol, Desertification, Endangered Species, Hazardous Wastes, Law of the Sea, Ozone Layer Protection, Tropical Timber 83, Tropical Timber 94, Wetlands.

The climate varies from cool summers and severe winters in north to subtropical summers and mild winters in south. Even though Nepal is a mountainous country, most of the cities, settlements, commercial centers and even the hydropower project sites are well below the temporary snow line (3000 m). Snowfall is rare in these locations.

Typical natural hazards are severe thunderstorms; flooding; landslides; drought and famine depending on the timing, intensity, and duration of the summer monsoons.

1.4 Hydropower potential of Nepal As a major contributor of the Ganga Basin, Nepal is one of the largest hydropower potential countries in Asia. Estimates say that Nepal has the potential for developing 83,000 MW of hydropower from different hydropower plants, including both large and small sized plants. Out of this, power plants of various sizes for a total generating capacity of about 42,000 MW are expected to be technically feasible.

1.5 Political system and government In 1951, the Nepalese monarch ended the century-old system of rule by hereditary premiers and instituted a cabinet system of government. Reforms in 1990 established a multiparty democracy within the framework of a constitutional monarchy. An insurgency led by Maoist broke out in 1996. The ensuing ten-year war between insurgents and government forces witnessed the dissolution of the cabinet and parliament and assumption of absolute power by the king. Several weeks of mass protests in April 2006 were followed by several months of peace negotiations between the Maoists and government officials, and culminated in a November 2006 peace accord and the promulgation of an interim constitution. Following a nation-wide election in April 2008, the newly formed Constituent Assembly declared Nepal a federal democratic republic and abolished the monarchy at its first meeting the following month. The Constituent Assembly elected the country's first president in July. The present government is the second after the Constituent Assembly election.

1.6 Hydropower development policy, status and private sector Nepal has focused on hydropower development by recognizing this sector as a potential economic backbone of Nepal. Different policies and regulations have been promulgated for harnessing the hydropower potential of the nation. The 1992 policy stands as one of the milestone to introduce private parties as the hydropower developers. The government has strategically supported for the development of hydropower sector.

Nepal is endowed with tremendous hydropower potential. However, only about 1.5% of its total feasible hydro potential (42,000 MW) has been harnessed so far.

The Integrated Nepal Power System (INPS) has a total installed capacity of about 685 MW of which about 631.3 MW is generated from hydro resources, the rest from thermal and multi fuel power plants. Of the total installed hydropower plants capacity, 92 MW (Kulekhani I and II) constitute seasonal storage plant and the rest run-of-the-river schemes. Besides, there are a number of isolated systems, micro and mini-hydro power plants and solar PV stations (total of 4.6 MW), which cater to the energy-need of the rural populace.

The annual energy available in the INPS in 2009/2010 was about 3130.8 GWh with a peak demand of 812.5 MW. The peak deficit of INPS in the same year was about 392.5 MW (At 18:25 hr, Jan 20, 2009). With an annual population growth of 2.2% and a sluggishly moving generation, the existing load deficit of the construction of new project is inevitable.

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2. PROJECT BACKGROUND

2.1 Project development agreement The Department of Electricity Development (DOED) of Ministry of Energy (MOE) of Government of Nepal (GON) offered a contract on BOOT basis to a firm or joint ventures to develop Kabeli-A Hydroelectric Project. This includes financing, construction and operation of the project. DOED evaluated the bids and awarded the bid to Butwal Power Company Limited in joint venture with Shangri-La Energy Ltd, Nepal; SCP Hydro Intl Inc, Canada; Asia Pacific Power-Tech Co Ltd, China; and Khudi Hydropower Ltd, Nepal through International Competitive Bidding (ICB) as the most competitive bidder. The winner JV formed a project company called Kabeli Energy Limited (KEL) in compliance with the stipulated process. After a number of technical and legal processes, a Project Development Agreement (PDA) was signed by DoED and KEL for the development, operation and transfer of the project on 31 January 2010. Actually, this agreement designated to KEL as the project company and allowed it to develop the project.

2.2 Kabeli Energy Limited, the Developer Kabeli Energy Limited (KEL) is formed for the development of KAHEP. This is a joint venture company with Butwal Power Company Limited and Shangri-La Energy Ltd, Nepal; SCP Hydro International Inc, Canada; Asia Pacific Power-Tech Co Ltd, China; and Khudi Hydropower Ltd, Nepal. The company will build, own, operate and maintain the project during the Concession Period (5 years for study and construction phase and 30 years for operation effective from the date of signing of PDA) for the purpose of supplying electric power to Nepal Electricity Authority in accordance with the Power Purchase Agreement. Upon expiration of the project development agreement, KEL will transfer ownership of the Project and all Project Facilities to GoN in good running condition. For the duration of Concession period, KEL is the developer of the KAHEP.

2.3 Power Development Fund Power Development Fund (PDF) has been set up with the initial capital of US$ 35 million by Government of Nepal and the World Bank (WB) to provide partial funding to supplement private sector financing for the development of Nepal’s hydropower potential. The PDF will be available to partially finance long-term debt for developing hydropower project and supporting infrastructures including access road and transmission systems. Kabeli-A is the first project to be funded through PDF and will be funded by the World Bank. As per the initial agreement, WB will contribute for 40% of the project cost, consortium of Nepalese banks will invest another 40% and the developer company will invest 20% in the form of equity. The consortium has already signed a memorandum of understanding with KEL regarding the investment. Since the construction of KAHEP will receive fund from PDF and Nepalese banks’ consortium, the project will not face financial constraint and is expected to complete within stipulated schedule.

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3. PROJECT STAGE

3.1 Project identification and 1998 feasibility study With initial identification during the Koshi River Basin Master Plan Study (1983-85), successive studies formulated the 30 MW Kabeli-A Hydroelectric Project. Feasibility Study and EIA of the project was carried out in 1998 by a consultant - Nepalconsult Pvt. Ltd. - on behalf of the then client - Nepal Electricity Authority (NEA).

3.2 Updated Feasiblity Study in 2010 After winning the KAHEP under competitive bidding, the Project Company, KEL, hired a consultant Hydro Consult Pvt. Ltd. for the Updated Feasibility Study of the project. The updated Feasibility Study is of the project has been already completed.

The study updated the previous studies, and conducted topographical, hydrological, sedimentological, geological, geotechnical and environmental studies. It also defined the project layout and configuration, project optimization, installed capacity, energy generation and project cost.

3.3 Physical model study and detail design After completion of the updated feasibility study, the Updated Feasibility Study Report has been submitted to the Department of Electricity Development (DoED) for getting necessary approval. Some changes might be needed in the future as per the comments from DoED.

A Physical model study of the headworks has been started and is being carried out at Hydro Lab Pvt. Ltd., Nepal. As per the outcomes of the model study, the design of headworks may need some modification in the future.

In the mean time, Hydro Consult Pvt. Ltd. is carrying out the detail design of the project. Detail design is expected to come up with the updated bill of quantities for the project.

3.4 Tendering While model study and detail design are ongoing, KEL wishes to offer the tendering of the project. The project construction has been divided into seven lots. The first three lots are considered as the pre-construction lots. They are the construction of Access road (Lot 1), Access tunnel/Test tunnel (Lot 2) and Permanent camps/housing (Lot 3). The major four lots of construction involve the construction of surface civil structures (Lot 4), underground civil structures (Lot 5), hydromechanical works (Lot 6) and electromechanical works (Lot 7).

This Project Description Report is prepared to provide the basic information of the project to the potential bidders during the prequalification stage.

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4. FIELD INVESTIGTIONS

4.1 General During this study field investigations like Topographical survey and maps preparation, Hydrological and sedimentology, geotechnical investigations were carried out and their results hve been presented.

4.2 Topographical Survey The topographic survey of the project area was carried out. The headworks area, powerhouse, penstock, surge shaft area and reservoir area were surveyed. The survey maps were prepared in 1:1000 scale maps. Survey of access road and headrace tunnel (HRT) was performed as a strip survey. These maps were prepared in 1:5000 scale maps.

4.3 Hydrology The summary of Hydrological analysis result has been presented in this section.

4.3.1 Catchment physiography

The Kabeli River constitutes one of the tributaries of Tamor River and Tamor River is one of the major rivers of the Sapta Koshi Basin.The Kabeli basin is located in between latitudes 27° 16' and 27° 17' N and longitudes 87° 42' and 87° 43' E .The Sapta Koshi Basin drains Eastern Development Region of Nepal.

The catchment of Kabeli River at the proposed project site has characteristics of mountainous catchment. The catchment area of the Kabeli River is 864 km2 at the proposed intake site. The catchment area above the permanent snow line (El. 5000m) is about 0.5 km2 only. It has elevation ranging from El. 560 m to El. 5600 m. Catchment characteristics of project site is presented in table 4.1.

All above mentioned drainage areas and elevations are based on the latest 1:25000 and 1:50000 scale topographical maps compiled from aerial photography of 1996 and produced by Survey Department in co-operation with the Government of Finland.

4.3.2 Drainage

The Kabeli River is one of the tributaries of the Tamor River which itself is one of the major tributaries of Sapta Koshi River basin. The River flows with an average river slope of about 1 in 100 in vicinity of Headworks area of project. Tawa Khola, Phawa Khola and Inwa Khola are the major tributaries of the Kabeli River.

According to the hydrological regions of Nepal categorized by the study conducted by WECS and DHM, the catchment area belongs to the Hydrological Region 1. As per the hydrological study conducted by WECS and DHM the value of Monsoon Wetness Index (MWI) in the region is estimated as 1500 mm.

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Table 4-1: Catchment characteristics

Elevation, masl Intake Area Powerhouse Area

Area in km2 % of total area Area in km2 %

Above 5000 0.5 0.1% 717.0 18.2%

Between 5000 m and 3000 m 177.5 20.5% 1325.0 33.7%

Below 3000 m 686.0 79.4% 1888.0 48.1%

Total catchment area 864.0 100.0% 3930.0 100.0

Figure 4-1: Kabeli catchment above the intake site

4.3.3 Flow measurement observations

The discharge of Kabeli River was measured by using current meter during the site visit. The measured flow is presented in Table 4-2.

Table 4-2: Flow measurement observations

Date of measurement

Flow, m3/s

Corresponding gauge height, cm

Remarks

09 Nov 2008 33.92 - Measured by current meter

20 April 2010 17.50 46.5 Measured by current meter

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4.3.4 Rating curve development at the Headworks and Tailrace site

The developed rating curve at headworks and powerhouse site are presented in Figure 4-2 and Figure 4-3 below.

Figure 4-2: Rating curve for the gauging station at the intake site

Figure 4-3: Rating curve at the tailrace site

MEAN MONTHLY FLOWS DERIVED BY USING DIFFERENT METHODS

The mean monthly flow derived by three methods is presented in Table 4-3.

Table 4-3: Mean monthly flows from various methods, m3/s

Month Correlation with Tamor at Mulghat

HYDEST MHSP

Jan 9.93 10.58 10.77

Feb 8.25 9.00 8.98

Mar 8.11 8.34 8.44

Apr 11.83 9.25 11.43

May 25.92 13.38 13.22

Jun 72.42 39.6 40.70

Jul 142.08 123.70 115.21

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Month Correlation with Tamor at Mulghat

HYDEST MHSP

Aug 151.09 145.96 134.98

Sep 106.31 110.73 103.14

Oct 49.49 48.52 46.98

Nov 21.95 20.32 22.77

Dec 13.61 13.11 14.92

Average 51.75 46.04 44.29

ADOPTED MEAN MONTHLY FLOW

The correlation of different long term DHM data of near by stations and Hydest and MSHP methods have been used for computing the mean monthly flow of the Kabeli River. The above table shows that the mean annual flow derived by later two methods is less than the correlated flow based on station 690.The flow given by HYDEST and MSHP methods is less than the flow given by previous one in wet seasons but seems to be within the reasonable range in dry seasons. Since station 690 being the mother catchment of Kabeli and having a long term data of 41 years, the mean monthly flow based on the catchment correlation and precipitation ratio is adopted. The adopted hydrograph is shown in Figure 4-4.

0

20

40

60

80

100

120

140

160

180

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Dis

char

ge

Month

Mean monthly hydrograph

Figure 4-4: Mean monthly hydrograph

4.4 Sediment study Field investigation is vital to sediment study. Kabeli-A is a PRoR project and the importance of sediment studies is even more for it. Therefore, field investigations were carried out for sediments too. The sediments are being measured in the monsoon season of year 2010. Crest gauges have been installed and taking sediment samples are being taken twice a day during the monsoon.

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4.5 Geology of Project Area Geologically the area lies in the Lesser Himalayan crystalline to meta-sedimentary rock. The project area consists mostly of granite with its subgroup of phyllite, quartzite, gneiss and feldspathic schist of the Taplejung window. The Headworks area comprises granite whereas surge shaft and Powerhouse areas consist of phyllite, schist, and quartzite. In general the orientation of the foliation is 30-40º towards north direction.

4.5.1 Engineering Geological Mapping

Engineering Geological mapping of the project area had been carried out during the1998 study. This study verified the then mapping and carried out mapping of the project components that are different from the 1998 study. Finally, Engineering Geological maps of the whole project area were prepared. Satellite images and aerial photographs were also used for the preparation of engineering geological maps.

4.5.2 Geophysical Surveys

As per the 1998 study, seismic refraction survey of the project area has been carried out at different sections. The findings of these studies were studied and utilized. Moreover, a new program for geophysical surveys by Electrical Resistance Tomography (ERT) was launched. The line and location of the 2D ERT lines were plotted on the topographic survey map after preliminary selection of project components. A total length of 3300 m was surveyed by ERT. The outcome of ERT survey was considered to fine tune the location and layout of the project components.

4.5.3 Drilling and field testing

As per 1998 study, a total of 296.6 m depth of core drilling was carried out during the past Feasibility Study. Since the dam, settling basin, surge shaft, tunnel inlet and outlet portals and powerhouse are not in the same location as envisaged in the 1998 study, the geology of these areas needed to be known confidently. Therefore, drilling and core testing program for those areas was discussed and agreed with the Client. If time constraint was not there, drilling should have followed the Geophysical surveys and its outcomes. However, to complete the investigation program as soon as possible, the drilling was carried out in parallel to ERT survey. Drilling points were located on survey map after preliminary layout of project components. A total of 185 m depth of core drilling was carried out during this study. The findings of the drilling were utilized to fine tune the location and layout of the project components.

4.5.4 Construction material surveying and testing

As obtained from the feasibility level design and quantity estimate, the approximate quantities of sand and coarse aggregate for KAHEP are 45763 m3 and 84660 m3 respectively. Similarly, a large quantity of boulders will be needed for the project, with likely demand of at least 35481m3. These construction materials should be preferably available in the nearby areas of the project, within a maximum of 2 km from the construction site. At the same time, the available materials should be of standard acceptable quality.

The quarry sites and borrow areas as proposed in the1998 study were visited and examined. Most of them were found in conformity with the requirement and the testing results of the 1998 study were referred to in this study. A total of 29 test pits (2 m depth) were excavated to assess the quantity and quality of the available construction materials. 30 representative samples were collected and the relevant lab tests were conducted.

Beyond this, the tunnel muck, especially that of granite, can be used as sand and even as coarse aggregate for construction purpose. The muck may need crushing to obtain desired grade of the aggregates.

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4.5.5 Summary of geological investigation

Kabeli-A project lies in the Taplejung window of the Lesser Himalyan Zone. Granite occupies the major portion of the project area, in addition gneiss, schist, phyllite and quartzite present in low proportion. Headworks of the project exhibit the granitic terrain. The Kabeli flows through the wide channel bounded by steep rocky slope at the headworks area. Comparatively the right bank seems more stable than left bank Granite of the area are slight to moderately weathered and samples from some outcrops show that the mineral altered to yield gneissic characters. The strength of the rock (UCS) is found up to 770.62 kg/cm2 from the core sample of headworks area. The intake area falls on sound rock cliff however accumulation of debris present close downstream from the Intake. The electrical resistivity profile along the debris deposits indicates the maximum thickness of debris is about 20 m. The short stretch of the Approach Tunnel is likely to pass beneath this debris. So the conformation of debris thickness needs to be verified by drilling or other method.

The settling basin is located beneath the granite rock mass. To find out the subsurface geological and geo-mechanical properties of rock, the area should be probed by drilling at least up to the depth of settling basin.

Similarly Headrace Tunnel is likely to pass through two third of its stretch via granite rock and remaining stretch through gneiss, quartzite, schist, and phyllites. The HRT is found passing beneath the maximum overburden of 880 m. No major weak or shear zone is observed during surface mapping along the Tunnel axis, however the possibilities of uncertainties is always in underground excavation. Thus those anticipated problem is assumed to be 10% of the total stretch of the tunnel and the respective cost is incorporated in this design phase of study.

The lithology of the surge shaft area is weak pelitic rocks. The strength of core sample from the drill hole at surge shaft found low value ranges from 125 to 216 kg/cm2. The RQD and Core Recovey are also in lower side. This must be the presence of fracture and joints and the degree of weathering increases towards the slope surface.

Penstock alignment and the powerhouse are to be founded on overburden. Problem due to differential settlement and bank erosion may arise in this setting. Presence of clayey fine sand, as reported in drill hole log, further increases such possibility. Surface draining during heavy rain or ground water, encounter at shallow level may aggravate such problem. Installation of piezometer of PVC pipe with capping is also recommended to monitoring water level fluctuation along the penstock hill slope. Provision for self draining contour drains may also be kept along the penstock hill slope.

Direct cone penetration Test (DCPT) N value in DH 5 (drill at anchor block site of penstock) is observed to be

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The seismic study shows that the project falls within the moderate seismicity recurrence area. The estimated Peak Beadrock Ground Horizontal Acceleration of the area and reference taken from other project shows that the seismic risk factor for the project components is low.

4.6 Environment and social condition of the project 4.6.1 Demographic Characteristics

The project area mostly lies in Panchthar district in Eastern Nepal. Some components lie in the border Village Development Committee (VDC)s of Taplejung district. Amarpur and Panchami VDCs of Panchthar District and Thechambu and Nankholyang VDCs of Taplejung District are the project affected VDCs. Most of the construction activities (powerhouse, intake, and tunnel) are located in the Amarpur VDC that is the most affected VDC. The project area is inhabited by Rai, Limbu, Tamang, Brahmin, Chhetri and Newar. Rai/Limbu is the dominant population. The total population of the project influenced VDCs is 21,100 having an average household size of 5.6. The literacy rate in the area is almost similar to the national literacy rate of 54.3%.

4.6.2 Settlement pattern

The settlement pattern of the project area is very similar to the other parts of rural areas of Nepal. Scattered settlement, comprising houses made of mud and stone with stone/slate, metal (CGI sheets), and thatched roofs, is found in the project area. However, few concrete houses in the market areas were also observed.

4.6.3 Occupation

The main occupation of the inhabitants in the project area is agriculture. Lowland with gentle slopes is used as cultivated land in the form of terrace in the project area. Paddy, maize and millet are the major crops that are grown manually. Concept of cash crops is in the basic stage and the local residents are reluctant to try new crops in their lands. Irrigation facilities are limited in the project area and confined to the certain patches of land. Most of the households have livestock for milk, ghee, and meat. The important livestock in the project area are goats, buffaloes, cows, sheep, hens, ducks, etc.

Recruitment in British and Indian army is also popular among the local residents. In addition, working in Malaysia and Gulf countries as foreign laborers is also a common pattern among the youth of the project area. Few individuals living nearby the market centers and roadsides are found to be involved in small business enterprises. It can be expected that most of the unskilled and part of the semi-skilled labor requirement of the project can be met at the local level.

4.6.4 Market/Bazaar

The major Market centers in the project area are Kabeli, Singhapur and Bhanuchowk of Amarpur VDC. These centers are located at the Mechi Highway and are the nearest service providers for the settlements around the project area. Kabeli bazaar (Plate 4-1) is at a 30 minutes walk from the headworks and Singhapur and Bhanuchowk are at three hours walk from the powerhouse site. In addition, local people also go to Phidim and Taplejung that are connected by Mechi highway for buying goods and services.

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Plate 4-1: Kabeli Bazaar

4.6.5 Water Supply

Around 50% of the population has access to piped water in the project area. United Nations Children’s Fund (UNICEF) has supported piped drinking water program in the area. Taps for public use along the foot trails were also observed during the site visit. However, the remaining population fetches water from the nearby natural springs for their daily use.

4.6.6 Energy Use

There is no electricity in the project area. Some households are using solar energy for lighting purpose on their own cost. Wood has been extensively used for household fuel requirements. Villagers primarily relyon woods for the cooking purpose as no adequate alternative energy source is available.

4.6.7 Transportation and Communication

Communication systems are underdeveloped and concentrated mainly within the market areas. However, the Nepal Telecommunications Corporation (NTC) network especially Code Division Multiple Access (CDMA) is available in the project area. Currently, no fax or internet service is available. Project area is linked by Mechi Highway from Birtamod, East West Highway. There is a regular bus service from Birtamod to Taplejung via Kabeli Bazaar. The access roads to connect intake and powerhouse areas to Mechi Highway are being constructed by local community and are being improved by KEL.

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5. TECHNICAL FEATURES

5.1 Project Location Kabeli-A Hydroelectric Project is located between the elevations of 400 and 600 m above mean sea level (masl) in the hilly terrain of Eastern Development Region. It utilizes the loop of Kabeli River with Tamor River, where Kabeli River is the boarder territory of Panchthar and Taplejung districts and Tamor is the boundary of Panchthar with Tehrathum districts. The loop contains Amarpur VDC of Panchthar district enclosing it from North, West and South directions. The headworks lies in the northern part of Amarpur VDC and the adjoining Nam Kholyang VDC of Taplejung district. About 5 km long waterway passes across Amarpur VDC. The powerhouse and tailrace are located at Pinase area in the southern part of Amarpur VDC. The project area is shown in Figure 5-1.

The approximate longitude and latitude of the proposed intake are 87° 44’ 56’’ E and 27° 16’ 40’’ N respectively and those of the powerhouse site are 87° 44’ 03’’E and 27° 14’ 11’’N respectively.

Figure 5-1: Location of the Kabeli-A Hydroelectric Project in National Map

5.2 Project Layout Kabeli-A project utilizes the loop formed by Kabeli River with Tamor River as shown in Figure 5-2. Moreover, selected drawings from Volume 2, Drawings have also been presented in Annex in this Executive Summary Volume. The project layout is shown in there. The references in these drawings are, however, not complete and one may require to refer to Volume 2 as required. The project is a pondage run-of-river (PRoR) type. Headworks is located in Dhuseni area of Amarpur VDC of Panchthar on the left bank and Thechambu VDC of Taplejung on the right bank; and is about 2.5 km upstream of Kabeli Bazaar. A diversion barrage with a provision for ponding will be constructed. Two intakes on the left bank will feed two underground settling basins. Water will then be passed through a 4550 m long headrace tunnel to Tamor River at Pinase area of Amarpur VDC. A surface powerhouse will be constructed on the left bank of Tamor River just upstream of the confluence of Piple Khola with Tamor River’s former bank. The gross head and design discharge of the project are estimated to be 116.80 m and 37.73 m3/s respectively.

Project Site

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Figure 5-2: Project layout of Kabeli-A Hydroelectric Project

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5.3 Salient features Table 5-1: Salient Features of Kabeli-A Hydroelectric Project

S.N. Items Description

1. Project Name Kabeli-A Hydroelectric Project

2. Location Amarpur and Panchami VDCs of Panchthar District and Thechambu of Taplejung District

2.1 Project Boundaries East 87° 45’ 50’’ E

West 87° 40’ 55’’ E

North 27° 17’ 32’’ N

South 27° 13’ 41’’ N

3. Type of development Peaking Run-of-the-river (PRoR)

4. Hydrology at intake

Catchment area 864 km2

100 year flood (Q100) 1920 m3/s

Probable maximum flood (Q1000) 2750 m3/s

Mean monthly flow 51.75 m3/s

40 percentile flow 37.73 m3/s

5. Headworks

Type/ Length of weir Barrage with 6 radial gates; 5 weir bays and one sluice bay

Full supply level 575.3 m

Crest elevation 561.0 masl

Gate Size 8.0 m Width X 5.5 m Height each

Intake type Tunnel intake on left bank

Intake size at trash rack 2 no. 5.4 m Width X 5.8 m Height

6 Diversion during construction

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S.N. Items Description

Diversion flood (5 year dry season flow)

154 m3/s

Diversion tunnel 360 m long; 4.8 m diameter D-shaped tunnel

Coffer dams 80 m at upstream side

90 m long at downstream side

7 Approach Tunnel from Intake to Settling Basin

Number 2 (1 each starting from each intake)

Length 80.9 m

Type Inverted D shaped; Concrete lined

Cross section Internal Finished Diameter 3.2 m

8. Settling basin

Type Underground settling basin

Number 2 basins with 2 hoppers in each

Length of uniform section 75 m

Total length including transition 113 m

Width 15.8 m each

Height 17 m

Flushing system S4 system

Flushing tunnel length and size 150 m long; 2.25 m D-shaped tunnel with 1.75 m dia. MS pipe

9 Access tunnel

Length 437 m

Type Inverted D shaped; shotcrete and rock bolt lined

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S.N. Items Description

Cross section Internal diameter 4 m

10. Waterways

10.1 Converging Pair Tunnels from outlet of settling basin to start of Headrace Tunnel

Length 60.2 m

Type Inverted D shaped; Concrete lined

Cross section Internal Finished Diameter 3.2 m

10.2 Headrace Tunnel

Length after pair tunnels 4326.8 m

Type Inverted D shaped; Shortcrete lined

Cross section Internal Finished Diameter 5.65 m

10.3 Surge Shaft

Type Underground and exposed to surface

Internal diameter 10 m

Height 51.2 m

10.4 Penstock

Material Mild steel

Length before bifurcation 223.3 m

Length of each leg after bifurcation

27.2 m

Internal Diameter 3.55 m

Shell Thickness 10-20 mm; partly ribbed

11. Powerhouse

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S.N. Items Description

Powerhouse type Semi Underground

Powerhouse size (L * B * H ) 34.8 m X 18.6 m X 31.80 m

12. Tailrace

Design tailwater level 458.5 masl

Length 93.1 m

Cross-section 4.9 m wide X 4.65 m high Rectangular RCC box culvert

Longitudinal slope 1 in 1500

100 year flood (Q100) in Tamor River

5980 m3/s

Probable maximum flood (Q1000) in Tamor River

8520 m3/s

13. Turbine

Turbine type Vertical Axis Francis

Number of units 2

Rated speed 375 rpm

Turbine axis elevation 457.64 masl

14. Power and energy output

Gross head 116.8 m

Rated net head 111.4 m

Design discharge 37.73 m3/s

Installed capacity 37.6 MW

Annual estimated energy excluding 6% outage

190.2 GWh

Firm energy excluding 6% outage 141.5 GWh

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S.N. Items Description

Secondary energy excluding 6% outage

48.7 GWh

15. Transmission line (Beyond the scope of this project)

Voltage 132 kV

Length 77 km

16. Access road

To headworks 2.3 km from Kabeli Bazaar to headworks

To powerhouse 8.7 km new construction; 3.5 km to be upgraded

17. Project Cost

Total cost 67.49 Million US$

Per kW cost 1794.9 US$

18 Financial analysis

Net present value (NPV) 8.77 Million US$

Benefit-cost ratio (B/C Ratio) 1.12

Internal rate of return (IRR) 12.04%

5.4 Major components 5.4.1 Peaking reservoir

KAHEP is a PRoR project. It accommodates the peaking reservoir within the project boundaries. Net live storage volume of the reservoir is 0.315 million m3. The headworks structure is used for required storage for ponding.

5.4.2 Barrage structure with gates, operating platform, intake, stilling basin and fish ladder

The barrage consists of a low crested Breast Wall Type Barrage with five weir bays and one sluiceway bay with width of 8 m and height of 5.5 m each. Individual bays are separated by 2 m wide piers. The sluiceway bay is separated by a divide wall from the weir bays. A 3 m wide flap gate has been designed to remove floating debris from entering into the intake.

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The stilling basin has a length of 50 m. The width of the basin is 60 m. The downstream sloping glacis (end sill) is in a slope of 1:2 (V:H). The total length of the barrage structure along the river including the upstream and downstream floors is 138 m. The operating platform is 3 m above the full supply level. There are two tunnel intakes on the left bank. The intake size at trash rack is 5.4 m width and 5.8 m Height. The right end of the barrage has been designed to act as an emergency spillway during extreme flood events. The length of the crest at most narrow section is at least 15 m. The barrage structure also consists of fish ladder.

5.4.3 Underground settling basin

There are two underground settling basins with 2 hoppers in each. Total length of settling basin is 113 m. The dimenstion of settling basins are as follows:

1. Length of Basin= 75 m

2. Breadth of Basin = 15.8 m

3. Length of Inlet Transition= 20 m

4. Length of Outlet Transition= 15 m

5. Maximum height= 17 m (excluding flushing drain of about 1 m depth)

5.4.4 Tunnel for diversion during construction

The diversion tunnel will be a D-shaped tunnel of 4.8 m diameter. It will have shotcrete and rock bolt lining. Two coffer dams will be constructed one each at upstream and downstream end. The top of coffer dam will be 5 m wide. The tunnel will be provided with a gate for reservoir flushing in the due course.

5.4.5 Access tunnel to headrace and settling basin

Access tunnel of D-shaped, 4 m diameter will be constructed. The total length of the access tunnel is 437 m and the tunnel outlet portal is located on the downstream left bank of the barrage. The same tunnel also facilitates the construction of tunnel as it is required to construct tunnel and the settling basin simultaneously. During operation period the access tunnel is used for the access to the gate control chambers. Altogether there are three gate control chambers of 5 m by 5 m dimension above every gate.

The constructruction of access tunnel is expected to complete before the mobilization of main construction contractors.

5.4.6 Headrace tunnel

The length of headrace tunnel with D-shaped of internal diameter 5.65 m after pair tunnels is 4327 m. The headrace tunnel will be mostly shortcrete lined and concrete lined for a stretch of about 500 m.

About 4310 meter long headrace tunnel is only the water conveyance system of the project. From the downstream end of the settling basin, about 100 meter stretch of two tunnels exists to convey water from basin to a single headrace tunnel. The HRT will likely to pass through major portion through granite rocks beginning from the inlet. The downstream stretch of the alignment is then passes through gneiss, schist, quartzite and phyllite. Tentative percentage of rock encountered through tunnel alignment is as follow:

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5.4.7 Surge shaft

A surge shaft of internal diameter of 10 m and height 51.7 m will be connected to the headrace tunnel through an offset tunnel near the tunnel outlet. It will be located near the outlet portal of the headrace tunnel and is placed at few meters offset from headrace tunnel. It is envisaged that a pilot tunnel will be constructed first and then the shaft will be expanded to the required diameter. Shotcrete and grouted rock bolt in pattern will be provided after excavation. The vertical ventilation tunnel of 3 m dia and 14 m height will be constructed.

5.4.8 Buried penstock pipe

The length of penstock before bifurcation is 223.3 m and after bifurcation length of each branch is 27.2 m. The range of shell thickness is 10-20 mm and partly ribbed.

There are total 3 nos of anchor blocks (VAB1, VAB2, and CAB1). VAB denotes anchor block having vertical bend and CAB denotes anchor block having combined bend (vertical as well as horizontal). Concrete casing of 0.3 m thick, base of thickness of 0.5 m and side projection of 0.5 m (on both sides) will be provided throughout the penstock pipe existing in between blocks (anchor blocks/thrust blocks). The bifurcation is located in between anchor block CAB1 and Powerhouse.

Three thrust blocks will be constructed at 30 m (inclined distance) interval between anchor block VAB1 and VAB2. The thrust blocks will be provided with d/s depth of 2m from the invert level of penstock pipe and 2.3m projection from either side. Anchor blocks as well as thrust blocks will be constructed of C20 concrete with 30% plums and nominal reinforcement to avoid uneven settlement and cracking. Moreover, C10 concrete is adopted for base of thickness 0.075m. The catch drain will be managed along the penstock alignment. In the vicinity of tunnel outlet portal, an effective drainage system will be constructed.

5.4.9 Semi-underground powerhouse and tailrace

The proposed powerhouse is a semi underground power house located on the right bank of Piple khola, in Amarpur VDC, Panchthar district with about 93 m long tailrace canal. Figure 5-3 shows the location of proposed powerhouse.

The outside dimension of powerhouse is 34.8 m long and 18.6 m wide. The excavated material will be used to construct the earthen bund at Tamor side.

S.N. Rock Type Length Percentage

1 Granite 3134 72

2 Feldspathic schist and gneiss

593 14

3 Quartzite and schist 153 4

4 Phyllite 447 10

Total 4327 100

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Figure 5-3: The location of the powerhouse

5.4.10 Powerhouse protection structures

Piple Khola is diverted left from its original flow direction enclosed between right and left retaining walls. There are C25 RCC retaining walls on both sides of the diverted piple khola. The length of rightside RCC retaining wall is 230 m and that of the left side RCC wall is 55 m. The height of these walls has been varied along the length as per the site condition and design requirements. Other portion of left side retaining wall is constructed of gabion boxes of height 2m above a 3 m high stone masonary wall of length 150 m.

Likewise, earthen bund will be constructed along left bank of Tamor River from the end of hill ridge-line down to Tamor River to protect powerhouse area from flood. The average length and width of the bund are respectively132 m and 32 m. The maximum height of the bund is 10 m from the existing ground level. The C25 RCC cutoff wall having length 115 m and height 8.5 m (max) is provided at the Tamor bund in order to protect powerhouse and tailrace canal from the adverse effect of seepage water. Riprap work is proposed at the downstream end.

5.4.11 Hydromechanical components

The hydromechanical components for the project include gates, stoplogs and penstock pipe. The barrage has 6 radial gates, six stoplogs groove and one stoplog body which is operated by single gantry crane. There are alltoghter 16 numbers of gates including 6 radial gates, 3 numbers of stoplogs body, 2 numbers trashrack, 147 m flushing pipe, diameter 1.75 m, 250 m steel penstock pipe, diameter 3.55 m, bifurcation, bends and manhole. The thickness of penstock pipe is varing from 10 mm to 20 mm.

5.4.12 Electromechanical components

The butterfly valves, turbines, generators and all electromechanical accessories of service bay, control room, indoor switchgear room, electrical/mechanical workshop and auxiliary equipment needed for ventilation and cooling are the scope of work under electromechanical components. Two units of vertical axis Francis turbines with rated speed 375 rpm will be installed. Two generators with rated capacity 18.79 MW; speed 375 rpm; frequency 50 Hz; rated voltage 11 kV will be installed. Two units of three phase transformer with rated capacity of 22.5 MVA and frequency 50 Hz will be installed.

TAMOR RIVER

PIPLE KHOLA

POWERHOUSE AREA

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5.4.13 Switch yard

The outdoor switchyard area is located close to the powerhouse. The switchyard covers 55.4 m x 38.75 m total area upstream of powerhouse. The work includes the construction of compound boundary fencing with an entrance gate.

5.4.14 Access road

• Access road to headworks

The alignment of access road to headworks runs along the left bank of Kabeli River. The length of the road is approximately 2.3 km from nearby Mechi Highway. This road is expected to complete by the time of mobilization of the main construction contractors.

• Access road to powerhouse

The access road alignment starting from the Mechi Highway at Mildanda is being constructed under local participation. A total of 3.5 km of track is already opened and a new track of 8.7 km is being opened by the villagers. This road is expected to complete by the time of mobilization of the main construction contractors.

5.4.15 Camp area (housing)

Permanent camp area (housing) will be constructed at both headworks and powerhouse areas. The housing at headworks will be about 2 km towards Mechi Highway from the barrage and will be near the Highway. The housing at powerhouse area will be at the ridge top just besides the surge shaft location.

The temporary housing and camps needed during construction shall be constructed by the contractors. KEL will allocate the land at a fair distance from the construction areas for establishing the temporary camps.

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6. CONSTRUCTION SCHEDULE AND PLANNING The updated project schedule will be made available to the bidders at the time of tendering. The construction schedule attached herewith (Figure 6-1) is as per the Updated Feasibility Study. It was prepared for the major construction activities and some preparatory work at site. The overall estimated construction time is about 3 year and nine months.

The construction of the project will involve work at four sites simultaneously; they are: work at headworks, work along tunnel alignment including surge shaft, work along penstock alignment and powerhouse area. Since the diversion tunnel has been proposed for diverting water at weir, the weir/barrage care should be taken to finish the work in shortest possible duration. Similarly, headrace tunnel has no intermediate adits and it has to be progressed from two ends only. Therefore, the tunnel construction may take long time. Construction of headrace tunnel and construction of headworks structure are the most critical activities in this project with longest duration. Considering this, the access tunnel to the underground settling basin and headrace tunnel will be constructed prior to the mobilization of main civil construction contractors.

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Figure 6-1: Proposed Construction Schedule for KAHEP