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    KATHMANDU UNIVERSITY

    School of Engineering

    A Report on Internship Works

    Required for the

    Partial Fulfillment of the Degree in

    Bachelors in Civil Engineering Program with Specialization in Hydropower Engineering

    Host Organization: Mailun Khola Hydropower company.

    Baluwatar, Kathmandu, Nepal

    Submitted By Supervisors

    Aashutosh Timilsina (61) Dr. Damber Bahadur Nepali

    Samip Dhungel (64) MKHP

    Prabin Karki (72) Er. Bikash Thapa

    Prabeg Sharma (73) Kathmandu University

    Department of Civil and Geomatics Engineering

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    Acknowledgment

    We would like to thank to Department of Civil and Geomatics Engineering, KathmanduUniversity for providing us with the opportunity to gather experience in the industry.

    We would like to express our sincere gratitude thank Dr. Dambar Bahadur Nepali, CEO,

    MKHP, for taking us under his supervision and guiding us through the time frame with his

    expertise and experience.

    We would also like to thank Er. Sunil Gupta and Er. Ashish Shrestha for their guidance

    while we were at the hydropower site. Also every support staff at the site office for their

    hospitality and warm welcome.

    We would also like to express our gratitude to the local people of Dadagau VDC

    who were fairly inquisitive of our presence and yet supportive.

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    Symbols and Abbreviation

    DCGE Department of Civil and Geomatics Engineering

    RoR Run-of-River

    HEP Hydroelectric Project

    HPP Hydropower Project

    MKHP Mailun Khola Hydropower Company Pvt. Ltd.

    KU Kathmandu University

    lps Liter per second

    m Meter

    m/sec Meter per second

    m^3 /sec Cubic meter per second cumec

    MW Mega Watt

    NEA Nepal Electricity Authority

    NRs. Nepali Rupees

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    Table of Contents

    1. Introduction ...................................................................................................5

    a) Objectives

    b) Scope of Work

    c) A system overview

    2. Internship Activities and Future Plan......................................................... 7

    3. Site Report...................................................................................................7

    a) Background

    b) Objectives

    c) Findings

    i. Headworks

    ii. Settling Basin

    iii. Forebay

    iv. Penstock

    v. Powerhouse

    vi. Tailrace

    vii. Electromechanical Components

    viii.Socio-Economic and Environment aspects

    d) Deviations from proposed design and reasons.............................23

    4. Office Work ...........................................................................................26

    5. Design Report.........................................................................................27

    a) NyamNyam Khola additional water design

    b) Check of mailun khola Catchment area

    6. Conclusion...............................................................................................37

    Annex A: Pictures

    Annex B: Power Energy Calculation

    Annex C:Project Layout

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    1. INTRODUCTION

    1.1Background

    One of the major efforts of Department of Civil and Geomatics Engineering is toprovide full-fledged in-house internship in any reputed organization/industry of Nepal

    and/or abroad that specializes in Hydropower Development. The Civil Engineering

    Program has been, therefore, designed with seven semesters of in-campus courses at

    the University totaling 141 credit hours and one semester of off-campus internship (3

    credits) inclusive of the final project works (9 credits) at the Host Organization.

    After the completion of their in-campus works, the final year students must work at

    Host Organization related to hydropower development as interns. The internship will

    be for a minimum of 6 working weeks with 8 hours per day of work load for allowing

    the students the opportunity to corporate knowledge, hands on technical skills, soft-

    skills and potential placement while at the same time the Host Organization would

    benefit from the lead-time and human resource identification. This would create a

    synergy between Host Organization and academia.

    For this, we had an opportunity to work in at Mailun Khola Hydropower Company

    Pvt. Ltd.. as interns.

    Introduction to Mailun Khola Hydropower Project

    The Mailun Khola Hydropower Project (MKHP) site is located in the BhoteKosi (Trisuli) Basin in Rasuwa District of Bagmati Zone in the Central Development

    Region of Nepal. The scheme has a planned capacity of 6 MW and diverts water from

    the Mailun Khola for power generation. The powerhouse is proposed to be located

    near Mailun Dovan on the right bank. The headwork is located on the left bank of

    Mailun Khola at elevation 1047.5 amsl. The headworks consist of a diversion weir

    with side intake, desanding basin and forebay. After the forebay the water is

    conveyed to the powerhouse with a 1550 m long steel penstock pipe. The gross head

    developed by the scheme is 153.7 m and the total turbine discharge is 5.2 m3/sec.

    The main structures are on the surface and comprises of construction works of the

    head works, Disilting basin, forebay, saddles, anchor blocks , powerhouse & tailrace

    canal and the hydro-mechanical works including penstock pipe, gates, stoplogs and

    trashrack.

    The access to the Project site is by a 75 km long black topped road from

    Kathmandu to Dhunge of Bidur Municipality plus 12 km motorable gravel road upto

    Jagate Danda. From Jagate Danda access roads of 11.5 km and 1.1Km have been

    newly constructed upto mailun dovan and Nyamnyam dovan respectively. The

    last section of the road has been constructed by the project itself.

    The headworks site and the powerhouse site are located at 1047m and 905m

    above sea level respectively. The distance between the powerhouse site and

    headworks site is about 1.6 km.

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    1.2Objectives

    The primary objectives of the internship work are as follows:

    a. To get exposed with professional engineering duties and responsibilities.

    b. To develop the proficiency of functioning in diverse engineering and managerial

    settings based on core knowledge, skills, attitudes and aptitudes acquired during

    the in-campus semesters.

    c. To be aware of engineering norms, values and ethical practices.

    d. To be acquainted on how to educate and motivate clients about the activities of

    Host Organization.

    1.3Scope of WorkThe scope of internship work can be summarized as follows:

    a. To be involved in day-to-day work as instructed by the supervisor from the Host

    Organization.

    b. To assist the supervisor and to be in consistent communication with the supervisor

    to accomplish the objectives put forward within the period of internship.

    c. To utilize all the theoretical and practical knowledge gained in order to solve the

    problems faced by the Host Organization under the instruction provided by the

    supervisors.

    d. To accomplish engineering and managerial tasks required by the supervisors underengineering norms, values and ethical practices.

    1.4A system Overview

    Lower Mailun Khola Hydropower Project. is in its final stage, the construction of the

    hydropower project is complete and while we were at the Company, wet test of the turbine

    and a system synchronization was done. In fact the only reason MKHP is not producing

    electricity already is because it is awaiting permission from NEA.

    The Site is located Dada gau VDC in Rasuwa district.

    The Feasibility study was done by : Star Consultancy (P) Limited

    The civil works was completed by Contractor High Himal Hydro

    The Electro mechanical component, supply and fixing was done my Andritz Hydro India.

    The transmission Line was constructed by the contractor -Urja Nepal.

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    2. Internship Activities and Future Plan

    Our internship program was divided into three major parts, they are

    1. Site Visit: We visited the site for the first leg of our internship, we were briefed by our

    supervisor, Dr. Damber Bahadur Nepali, before we went to the site over the phone. He asked

    us to observe the components of the hydropower and get a basic idea of the project. There is

    a separate section, below that explores in depth our findings at the site and later on.

    2. Office work: For the second leg of our internship program, we were asked to return from the

    site, and report to the Head office at Baluwatar. The report preparation from the site and

    study of inception report, feasibility report and other documents is the work we did at the

    office just after arrival from the site. Such work led to a report and a presentation submitted

    to our supervisor. Also we were involved in data entry activity during the office time.

    3. Design work: The last leg of our internship involves the design and study of intake site, this is

    also mentioned in detail in the later sections under a heading called design work report.

    Future Plan

    As we have now completed our internship program at MKHP, we will now proceed towards

    working on our Final Year Project Report. Our Supervisor has agreed to provide us with whatever

    data and guidance he to help us do our project.

    Our plan as of now, is to work on the possibility of another Hydropower Project upstream of

    the current site, such as that the tailwater will supply the intake of the Lower Mailun Khola HPProject.

    Site ReportSite Visit Report

    The access to the Project site is by a 75 km long black topped road from Kathmandu

    to Dhunge of Bidur Municipality plus 12 km motorable gravel road upto Jagate Danda.

    From Jagate Danda access roads of 11.5 km and 1.1Km have been newly constructed upto

    mailun dovan and Nyamnyam dovan respectively. The last section of the road has been

    constructed by the project itself.

    The main structures are on the surface and comprises of construction works of the

    head works, Desilting basin, forebay, saddles, anchor blocks , powerhouse & tailrace canal

    and the hydro-mechanical works including penstock pipe, gates and trash rack.

    As the first part of our internship program we were asked to visit the site and gain an

    over view of the project. We started our internship project from 31stMarch, 2014.

    We met with the Civil engineer stationed there, Er. Sunil Gupta, who had overseen the

    construction of the project.

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    Other Engineer at the site, was Er. Ashish Shrestha, who was an Electrical Engineering

    Graduate form Kathmandu University itself.

    Er. Sunil Gupta introduced us to the project status.

    OBJECTIVES

    The primary objectives of the site visit were:

    To be familiar with the project site and different project components.

    Assess suitability of the sites for construction of the different components.

    Brief inspection of project areas morphology, geotechnical and foundation

    conditions

    Compare and contrast Layout of civil components from the Feasibility Study

    Report later on during the internship

    The following works were carried out during the site visit:

    Walk through the project area to assess the head works, Disilting basin, forebay, saddles,

    anchor blocks , powerhouse & tailrace canal and the hydro-mechanical works including

    penstock pipe, gates, stoplogs and trashrack.

    Assessment of the project components and field discussions on their merits and demerits,

    Enquiry with the locals about the Mailun Khola and flood occurrences

    Assessment of availability of construction materials.

    Dismantling the temporary diversion structure at upstream

    Desander filling, Penstock filling and Turbine spinning

    Observe Electrical checks at the switch yard

    Observe Erection of transmission line for Power evacuation

    FINDINGS

    1. Headworks

    Headworks, also referred to as diversion works, abstracts water from the river and

    diverts it into the waterways of the HPP for power generation at various flow conditions and

    assists safe discharge of flood. As such, the headwork consists of all structural components

    required for water diversion, energy dissipation, handling of sediments, and floating debris.

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    The design of the various headworks components will vary depending on site-specific

    conditions, such as topography, geology, hydrology, meteorology, sedimentology and

    environment, and needs to be adjusted accordingly. Every HPP has a unique headworks

    arrangement. Consequently, the selection of headworks site should be based on the locations

    technical, economic and environmental suitability for the major components that form theheadworks.

    Features of ideal headworks

    1. Withdrawal of required amount of water

    2. Flood bypass

    3. Minimization of sediment entry

    4. Settling basin control

    5. Economic and minimum operation and maintenance

    6. Minimization of hydraulic losses

    7. Prevent formation of air vortices

    8. Prevents floating debris, trash and ice from entering the water conveyance system

    9. Easy and economical to construct

    Intake

    Intake is the structure to obtain the required quantity of water from the river or the reservoir.

    Its function is to divert the required amount of water to the waterways.

    Salient features of Intake at MKHP

    The intake at MKHP is a side (lateral) intake.

    The headworks shall be capable of withdrawing the design discharge of 5.2 m3/s

    including discharge required for flushing. Steel lined spillway for safe passage of water fitted with gates.

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    Intake is located near the spillway gate to avoid the riverbed from building up at the

    intake. So no under-sluices was present.

    No gravel trap

    A broad crested weir is constructed adjacent to the intake such that the required

    submergence of the intake is maintained high enough for necessary abstraction offlow even during dry seasons and for the prevention of air entrainment in the

    conveyance system. The diversion weir is a concrete structure of length 11.0 m

    The diversion weir including the intake section shall permit safe passage of design

    flood equivalent to 1 in 100 year flood.

    No scour protection for weir

    No seepage control measures at weir

    2.Settling Basin

    Settling basin is the structure to remove suspended sediments from water before

    conveying it to the powerhouse. The main principle of the design of settling basin is to

    reduce the mean velocity of the flow by increasing the cross sectional area.

    The dimensions of the desanding basin depend on the characteristics of the river, the

    design discharge, and the particle size to be removed, which is 0.20 mm for hydropower

    projects with high heads. The selection of particle size to be excluded at desanding basin

    was based on following criteria of head and turbine type:

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    Salient features of Desilting Basin at MKHP

    A double chambered conventional type surface desanding basin is constructed on

    the right bank of the mailun Khola.

    The length of the main basin is 45 m long, 4 m wide and 4 m high including the

    free board of 0.5 m.

    The settled silt particles will be flushed back to mailun Khola through the flushing

    culvert with boulder riprap at the exit.

    The trap efficiency of the desanding basin provided for the particles equal to or

    bigger than 0.2 mm is 90%.

    Vertical lift gates are provided at both ends of the desanding basin so that

    desanding flushing can be carried out separately. Discharge from the end of the

    desanding basin will be passed into the forebay before it is conveyed into the

    penstock.

    Particle Size (mm) to be Excluded at Desanding Basin

    Head (m) Maximum size particle (mm)

    100200 0.61.0

    200300 0.50.6

    300500 0.30.5

    > 500 0.10.3

    Turbine Type

    Kaplan 1.03.0

    Francis 0.41.0

    Pelton 0.20.4

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    3.Forebay

    It is a structure located at the beginning of the penstock pressure shaft satisfying the function of

    supply required flow to the turbine during start up, accommodate the rejected flow during

    shutdown, reduce water hammer effect is called forebay. Forebay is especially constructed between

    the conveyance system and penstock pipe.

    Functions of forebay:-

    1. It allows transition from open channel to pressure flow conditions.

    2. Regulates the flow into the penstock, particularly through the release of excess water

    into a spillway.

    3. It releases the surge pressure as the wave travels out of the penstock pipe.

    4. It can also serve as the secondary/final settling basin and trap some particles that enters

    the headrace downstream of the settling basin.

    5. Forebay can also provide water storage for use during peak power demand period.

    Basic Design Considerations:

    1. Forebay should be designed to serve as the secondary settling basin.

    2. Lower sediment concentration can be used because only particles that have escaped

    from the settling basin or those have been eroded from the headrace canal is expected

    in the forebay.

    3. Storage depth for the sediments below the pipe invert should be allowed (min of 300mm

    clearance).

    4. Depth of basin should be sufficiently high to allow required depth of submergence.

    It must be able to store 2 to 3 minutes of the design flow can be safely stored in the tankabove the minimum pipe submergence level.

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    5. Qf = 2*Qd where Qf = Forebay Discharge

    Qd = Turbine Discharge.

    (Because during closing of the valve, there will be backflow occurred from the penstock

    and the discharge from conveyance system is also continue for short time.)

    6. Easily flushing principle.

    7. The basic principle of the design of the forebay area should follow the design standard of

    the desanding basin.

    Characteristics of Forebay built in the MHP Project:-

    1. It acts as a regulating pondage to cushion the impact of sudden load rejection or load

    acceptance at the end of the desanding basin.

    2. The design of forebay area follows the design of desilting basin with the dimensions 8m

    long, 8.4 m wide and 8 m high with 0.5 m of freeboard.

    3. The adequate height of submergence is 1.5 m is adopted.

    4. Adequate invert level below the penstock is provide to collect the sediments.

    5. Flushing channel is not provided instead manual cleaning of sediments can be done.

    Francis turbine can withheld the maximum size of sediments of 0.4mm to 1.0 mm and

    the desander is designed to trap the sediments greater or equal to 0.2mm with 90%

    efficiency. Which makes minimum sediments on the forebay thus flushing channel is

    excluded making it economical.

    6. As forebay is incorporated with desilting basin the separate spillway for the forebay is

    not needed.

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    4.Penstock

    Penstock is designed to carry the design discharge from the forebay to turbines with

    least possible loss of head in the powerhouse. These are pressurized conduits which

    convey water to the turbines from free water surfaces. The most economical penstock will

    be the one in which the annual value of the power lost in friction plus annual charges such as

    interest, depreciation, maintenance will be a minimum.

    Considerations in penstock for its durable and economical design:-

    1. Economic diameter of penstock

    An optimization study has to be carried out to calculate the economical diameter of the

    penstock pipe. The study is based on the increment of penstock pipe diameter and the value

    of energy gain with respect to the pipe diameter. Basically, a larger diameter pipe, for a

    given discharge, leads to smaller headloss resulting the power and energy to increase while

    on the other hand, a larger pipe means a higher capital investment. Therefore, a size that

    will give the least capital cost over the lifetime of the plant is considered to be the optimum

    diameter.

    2. Shell thickness of penstock pipe.

    3. Head loss in penstock pipe.

    Selection Criteria for the penstock alignment:-

    1. Forebay/ Surge tank Location

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    The forebay/ surgetank location should be chosen to give minimum penstock length for the

    economic reasons.

    2. Practical ground slope:-

    Flatter the ground slope less economic is the penstock since a longer pipe length is required

    for a lower head. But the slopes steeper than 1:1 the difficulty in laying the penstock, anchorblock and support piers may occur. The ideal ground slope for the penstock alignment is

    between 1:1 and 1:2 (V: H).

    3. Minimum number of bends

    Bends increases the head loss and require additional anchor blocks. Thus alignment should

    be straight as possible both in plan and elevation.

    4. Space for powerhouse area.

    The chosen alignment must be such that it is possible to construct a powerhouse at the end

    of the penstock.

    5. Stability

    Penstock alignment should be on stable ground because any ground movement can damage

    the pipe, support piers and anchor blocks.

    6. Other site specific conditions

    Other site specific conditions are in the crossings like local trails, roads, canal, this section

    should be either buried or high enough above the ground such that people and cattle can

    walk underneath.

    Types of penstock installations:

    1. Exposed penstock

    Penstock supported at pier or saddle support or penstock supported in ring girder are

    examples of exposed penstock.2. Steel tunnel liner (Embedded)

    These are located in a tunnel and fully encased in concrete or encased in a portion of a

    dam.

    3. Buried Penstock (Underground)

    These are partially or fully buried pipes. These are supported on the soil in a trench at a

    depth of 1.0m to 1.5m and after placement trench is backfilled.

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    Anchor Blocks

    Anchor blocks are generally designed as mass concrete encasing the penstock designed to

    withstand the weight of the pipe and water perpendicular to the pipe, friction on pipe on support,

    hydrostatic pressure at bend, component of weight of pipe parallel to pipe, and self-weight of the

    block. Anchor blocks are designed to withstand any load that the penstock exert on it and keep it in

    place by the virtue of its own weight and the bearing area. Due to the forces that act on anchor

    blocks, they are generally much more bulky than saddle supports.

    In mailun project, anchor blocks are provided at all bends. Total number of anchor blocks provided is

    17 and a block provided for bifurcation. An expansion joint is provided just downstream of each

    anchor block.

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    4. The pipes are supported by saddle supports spaced at regular intervals of 10 m and anchor

    blocks at each bend.

    5. 2 Nos of expansion joints are provided where penstock is exposed to environment.

    6. Reducers are installed for the smooth transition where the size of the penstock is reduced to

    maintain the pressure.

    7. The siphon crossing is made at a point where river crossing is done with two manholes and

    pressure releasing valves at both ends of the siphon to release the air entrapped and for the

    manual inspection of the pipe.

    5.Power house

    A power house is a structural Complex where all the equipments for power generation are

    suitably arranged.

    The basic requirement of powerhouse planning are

    A.Functional efficiency

    B.Aesthetic Beauty

    Depending upon the location, the powerhouse can be Surface or Underground.A surface powerhouse should have a stable foundation, if the foundation is weak then there

    should be application of special foundation treatments.

    The surface powerhouse located at Mailun Dovan. The surface powerhouse has two units of

    electro-mechanical equipment having total installed capacity of 6,000 kW.

    It is also required to have an area for service and maintenance and room for mounting control panel,

    transformer and high voltage panel in addition to office rooms. Generally, an overhead crane for

    installation of heavy equipment is also provided. Powerhouse is located so that it is safe from

    possible flood of 100 year return period.

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    The surface type powerhouse has been located on the relatively flat terrain on the right bank of

    Mailun Khola at Dovan. The location is safe above the HFL of both Mailun and Trishuli with provision

    of freeboard. The powerhouse will be 46 m long, 14 m wide and 21.86 m high. The powerhouse willcomprise of machine hall, erection bay, battery room, control and protection equipment etc. A

    switchyard of approximate size 30 m x 20 m has been located close to the powerhouse.

    POWERHOUSE DIMENSIONS AND UNIT PARAMETERS

    The computed discharge diameter of the runner of each unit is 0.61 m. The runaway speed of the

    turbine is 1699.60 rpm. Six numbers of poles are required in the rotor of the generator.

    The unit-to-unit centerline distance is a function of the installed capacity and the net head, the

    calculated value of which comes to be 3 m. The span of the overhead traveling crane is fixed at 8 m.

    6. Tailrace

    A tailrace canal is designed to pass the discharge after it has been utilized for power generation. A

    tailrace of length about 70 m release the water to Trishuli. Tailrace outlet is prepared by providing

    suitable transition with boulder riprap.

    The geological condition along the tailrace canal is similar to that of the powerhouse foundation. The

    tail water will be evacuated into the Trishuli River from right bank in a stable location.

    7.ElectroMechanical Components

    The Following were the important ElectroMechanical Components observed

    A.TURBINE

    B.The selection of type of turbine primarily depends upon the net head and available discharge for

    the generating unit. As confirmed by the results of detail calculation, a Francis turbine with a

    horizontal axis was the turbine of choice for the net head of 141.36 m and available discharge of 2.26

    m3/sec for single unit for the project.

    The turbine output capacity of each unit is calculated to be 3 MW. Single unit is not preferred due to

    the fact that total generation loss will occur in time of the unit breakdown. Besides, various

    guidelines give the value for minimum design discharge for continuous operation for Francis turbine

    is 50%.

    B. GOVERNOR

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    Each generating unit was supplied with an Electro-hydraulic governor. The governor consisted of

    speed sensing device, Electro-hydraulic actuator etc. required for regulating the speed and

    controlling the openings of the guide vanes of the turbine

    C. INLET VALVE

    One set of butterfly valve operated by a servomotor, provided with bypass valve ans dead weight,

    capable of being handled both electronically and mechanically.

    D. HIGH PRESSURE OIL SYSTEM

    Each set of generating unit has high pressure oil system, which consists of two sets of direct-coupled

    alternating current motor-driven self-priming pump of sufficient capacity, one acting as the main and

    the other as the stand-by.

    E. COOLING WATER SYSTEM

    The cooling water system provides necessary amount of cooling water mainly for the following

    equipment:

    Lubricating oil cooler

    Generator air cooler

    Transformer oil cooler

    Oil sump tank cooler

    F. UNIT BRAKING SYSTEM

    A unit braking system is installed to quickly bring the rotating parts of the turbine and generator to a

    stand still position, when the unit is being shut down. It is generally required that the time taken by

    the rotating parts to come to a stand still from 20% of the normal operating speed should be less

    than three minutes.

    G. AIR CONDITIONING AND VENTILATION SYSTEM (IF REQUIRED)

    An air conditioning system is installed for the control room. The fresh air is provided from the

    ventilation system. The system comprises of two sets of air conditioners, one acting as the main and

    the other as the stand-by unit. Each unit shall consist of a compressor of appropriate capacity, a

    thermostat and a humidistat. The operative temperature will be kept in the range of 20 to 260C and

    the relative humidity to be maintained around 60%.

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    H. FIRE DETECTION AND FIRE FIGHTING SYSTEM

    A complete fire detection system is planned to be installed in the powerhouse. The system shall

    comprise of smoke detectors and heat sensors installed in appropriate locations. The fire detection

    system shall automatically activate the appropriate fire fighting equipment as well as produceaudible and visible alarm signals.

    I. OVERHEAD TRAVELING CRANE

    An overhead traveling crane is installed in the powerhouse. The crane is capable of lifting the

    heaviest piece of equipment installed. The item with the maximum weight required to be lifted

    unassembled most probably shall be the generator rotor with shaft.

    The crane has one main hoist and one auxiliary hoist. The span of the crane is such that it covers all

    the major equipment to be serviced.

    8. Socio Economic and Environmental Aspects

    The ethnic distribution of the district shows that the area is inhabited mainly by Tamang, Lama,

    Gurung, Brahmin and Chhetri. The occupation of most of the ethnic groups is agriculture. Paddy,

    maize, millet, wheat and barley are the main cereal crops whereas potato and oilseed are main cash

    crops. Bidur, the district headquarters and Trishuli Bazaar are the main trading centre, where people

    are involved in commercial and service sector. The total population of the project influence area,

    Ward Nos. 8 & 9 of Dandagau VDC is estimated to be around 356 consolidated within 64 families. As

    per the schedule in EPR, 1997 It's Power generation that falls under 5MW. The transmission line at a

    potential difference 66KV, the Access road for the site would fall under the provision for

    rural(village) roads.

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    Mailun Khola Hydropower project would fall under the provision for an Initial Environment

    Examination. And its Transmission Line would have to do an EIA, which has been done.

    Environmental Impacts Observed

    Land Use: Non- arable land, ROR type. The Power house site is also non arable, with sandy soil

    and boulders

    The River: affects a rivers ecosystem and habitats, decreased water quality, danger to

    fishing, changing water levels. However, Namnam Khola will prevent the river stretch from

    completely drying off

    Wildlife Impacts: A transmission Line across the National park, felling of trees will affect

    wildlife.

    Erosion and Slope stability: The Headworks site was built by cutting the slope and this will

    cause instable slope, there has been no application of slope protection measures. The sut

    slope area where vegetation was cleared should be covered by planting plants to ensure

    greater stability. This has not been observed.

    Fisheries: There will with no doubt be a decrese in fish population in the river stretch.

    Fishermen will have to travel upstream for fishing. The aquatic life will be greatly affected.

    Socio- Economic aspect observed

    Rural Electrification

    Must be placed high on the priority list as there is no electicity in the village, the

    hydropower office is practically a cellphone charging station for a number of

    locals.

    Road Access

    The Access road that reaches the HP site has completely transformed the way of

    life of the local community, a significant percentage of which even find difficulty

    in Understanding Nepali.

    There is a bus service that makes one round trip a day, It takes approximately 80

    minutes to reach blacktopped road that leads to Dhunche from Dhunge.

    Employment

    The contractor given the resposibility for the construction of transmission lines,

    Urja Nepal, had to Bring in the labors to carry transmission lines to towers from

    elsewhere, this would suggest that there are not much people willing to do

    manual labour in the community. However, The scenario may be very different

    when it comes to employment at the HP for non manual work. However Later on

    we also found out that one of the reason for being late with production is that the

    local unskilled people had to be employed during the project.

    Small business:

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    A number of small businesses have sprung up in recent years. We were informed that the

    community has grown since the advent of the project. The businesses primarily provide

    goods, eating services, alcohol and livestock for meat consumption. There are no commodity

    shops.

    Demographic Change: Unknown

    Gender Impact:

    The presence of MKHP and other Project have greatly affected the roles taken up by

    women, Many women are employed as cooks and helpers in Camps. Women are given with

    income generation opportunity. This will directly impact gender equity.

    Cultural implications:

    Traditional approach to Life and Work has changed. There has not been any change in

    religious and tribal factors, the majority of people are still Tamang. Due to the presence ofa Market Social cohesion is strenghtened. Social Cohesion is also improved due to presence

    of the Hydropower.

    Health Impact

    There are possibilities of Health Impacts, Recent arrival of mosquitoes is a strong

    sign in the matter. There are no Healthpost or any store that sells medicine. The Health

    Impacts will show up slowly after the Environmental Impacts start to show. The possiblity

    of Disease previously unknown to the demography must not be ignored. The presence of

    alien population in the region increases the level of Risk the local population is exposed to.

    The Influx of Labor did also bring in the possiblity of STI's. But no posters or informative

    banners based on health impacts and suggesting prevention were seen at the site. It should

    fall under the moral implications for a HPP to at least provide basic knowledge to the local

    community in this regard.

    Education : The company has helped the local community by constructing a school building.

    Deviations from the proposed design and the reasons:

    After the study of the components we observed variations to proposed design and the actual site

    translation, the reasons and remarks were explained to us by our Supervisor.

    There has been numerous changes to the design through the development of the project. Major

    ones are as follows:

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    Change Reason Remark

    Change of intake location Huge landslide just above

    proposed head works.

    The head works construction

    site was shifted to a lower

    site, but still on the left bank.

    This also reduced the head

    from 372 m to 149 m. This

    greatly affected the power

    generation capacity of the

    project.

    Change of power house site Not ample space on the

    earlier proposed site.

    The Construction of power

    house was shifted to the right

    bank, because the cost ofexcavation was expensive.

    Use of siphon As against Aqua-duct Nepali streams and rivers are

    very prone to sporadic floods

    and also because the Mailun

    Khola is partially snow fed ,it

    was logical to not build an

    aquaduct and instead a siphon

    was installled to cross the

    bank.

    No surge tank Short length of penstock Because the penstock length

    is now reduced due to the

    shift of the head works, the

    need for a surge tank was not

    felt. This means the forebay is

    capable of handling the surge.

    No Gravel trap Because of the lack of space,

    so the desilting basin has theprovision to flush out the

    gravel.

    Short transition period from

    intake to basin,

    There should be long

    transition to uniform the

    velocity, ans the flow. To

    deposit sand. This would

    cause unequal deposition on

    settling bays.

    No shape. And maximum

    possible excavation was done.

    No ogee shape spillway, Because the velocity would

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    allow the broad crested weir.

    Slope stability not done Wait and watch approach Planning for bio engineering

    measures, Jute netting or wire

    mesh is thought of.

    No seepage control at

    foundation

    Seepage path would be long

    and be costly

    Because the slope is steep

    there is only a cut off wall,

    hence to stop the seepage

    there is red mud spread.

    There is still a danger of

    piping. In that case , grouting

    would be an option with quick

    setting admixture. This would

    require the diversion of the

    river. That will mean a huge

    loss to the project.

    Rip rap after weir to no riprap only boulder. Easy maintainance, cost cuts

    NyamNyam Khola addition To improve production,

    Nyam-Nyam is cleaner, which

    also has a license for 5MW

    power generation.

    Use of water from nyam nyam

    would be better as there

    would be less sedimentatuon

    at desilting basin, additional

    water for dry season.

    Other differences along the years

    Previous Present

    HRT 1820m HR Pipe 1550m

    t=14 to 8mm D=1.4 to 1.6m

    Surge Tank -- yes Surge Tank -- No

    L/B of Mailun L/B & R/B of Mailun

    Land Acquired Need to Buy

    Annual Energy 37.1734 Energy 34.538 GWh

    Q Mailun 1.6 Cumecs Mailun + Nyam 5.1

    PPA Rate Rs3/-6% 4Yr PPA Rs 3/78 & 5/35

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    Office Work

    The head office of MKHP is located at Subarna Shamsher Marg, Baluwatar, Kathmandu. After the

    visit to the site we reported at the head office. Dr. Damber Bahadur Nepali sir would now supervise

    us personally and guide us at the office and through our project.

    At office we were given two inception report of Lower Mailun and Middle mailun Hydropower

    Project. The inception report was made by Star Consultancy in 2008 . It was first proposed design by

    the contractors. They had proposed a cascade type of designs of three projects respectively Upper ,middle and lower mailun hydropower projects. Due to the accessibility , feasibility factors the design

    was modified and design of lower mailun was designed in 2009 by the consultant. The design of

    lower Mailun was implemented and modified as required to overcome the problems like landslides

    in the headwork site, accessibility of Powerhouse site, Layout of penstock, and many other factors.

    The difference in modified design, solutions to overcome the problems , reasons to change the

    design etc was studied ,listed and the best design of the project was figured out and studied. Then

    we were given the Feasibility Report of Lower Mailun Khola Hydropower Project. Which led us to

    understand process of planning and then finally implementing the project and the problems that

    would be faced during the project implementation, and how to over come it.

    The office work included helping the office with data entry jobs. This was the report that the

    company had to present to NEA after the tests of Switch Yard and control devices.

    Dr. Damber Bahadur Nepali gave us a Presentation Titled, Investment in Hydropower. The

    Presentation Discussed about the Development of Hydropower in Nepal, against popular belief he

    states that the Development of Hydropower is actually easy.

    We also discussed on the topic, Construction of CHILIME NEA, as a Vehicle for Development of

    Hydropower in Nepal Dr. Damber Nepali is a pioneer in the field of Hydropower development in

    Nepal. He has first hand experience of Developing a Hydropower Project in Nepal with out any alienfunding. The Model of investing in Power generation that Chilime Hydropower did, has made

    possible the Development of Upper Tamakoshi Hydropower Project of installed capacity 456 MW, a

    similar project being developed entirely by Nepali Investors. He discussed with us the importance of

    engineers taking initiative to dare to construct projects that will shape the future of the Country, It is

    important as an engineer to not only work with honesty but to also invest in Development Projects in

    Nepal. The most important thing we have learned in six weeks is this.

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    Design reportNyam Nyam Khola additional water design

    Nyam Khola is a major tributary of Mailung Khola. Mailung Khola is a tributary of Trishuli River, which

    is a major tributary of the Sapta Gandaki River Basin. The Gandaki River basin drains the Central

    Development Region of Nepal. Trishuli River basin has a drainage area of about 4850 km2at the

    gauging station located at Betrawati. Mailung Khola lies in Dhading and Rasuwa District and joins the

    Trishuli River at Mailun Dobhan. The catchment area at Mailun Dobhan is about 112 km2.

    Our approach is to feed the intake of Lower Mailun hydropower from the water collected at Nyam

    Nyam Khola. For this we have selected a site for intake at Nyam Nyam Khola, after that the

    catchment was calculated. The detail of the method and the calculation is presented below.

    Catchment Area Plotting and Discharge Calculation

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    The catchment area of Nyam Nyam khola was obtained as 25 sq. km.

    The discharge measured was taken as 1.22cumec which was measured in December 2008

    MIP method was used for estimating the flood discharge.

    Estimating the mean monthly flow using the MIP Method of Nyam Nyam

    Khola

    Input the following data

    Hydrological region(from figure): 3

    month in which flow was measured(1-12): 12

    measured flow: 1.22 cumec

    Tabulating the data

    Non-dimensional Measured flow Predicted flow

    Predicted

    Hydrograph

    Month constant (cumec) (cumec) (cumec)

    Jan. 2.71 0 0.000 0.88

    Feb. 1.88 0 0.000 0.61

    March 1.38 0 0.000 0.45

    April 1 0 0.000 0.33

    May 1.88 0 0.000 0.61

    June 3.13 0 0.000 1.02

    July 13.54 0 0.000 4.41

    August 25 0 0.000 8.13September 20.83 0 0.000 6.78

    October 10.42 0 0.000 3.39

    November 5 0 0.000 1.63

    December 3.75 1.22 0.325 1.22

    PLOTTING HYDROGRAPH

    Month X Y(Cumec)

    Jan. 1 0.88

    Feb. 2 0.61

    March 3 0.45

    April 4 0.33

    May 5 0.61

    June 6 1.02

    July 7 4.41

    August 8 8.13

    September 9 6.78

    October 10 3.39

    November 11 1.63

    December 12 1.22

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    To be conservative, the mean monthly flows obtained by applying factor of 1.5 have been adopted.

    Therefore the design for intake will take design discharge of 1.83 cumec, taking a factor of safety as

    1.5, This has been obtained by taking a mean monthly dry months from November to June.

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

    Factor 1.5 0.79 0.65 0.59 0.58 0.78 2.20 4.63 6.35 4.86 2.18 1.46 0.98 2.17

    MIP mean 0.94 0.71 0.51 0.39 1.02 2.36 5.70 9.83 6.49 3.15 1.4 1.22 2.83

    Mean monthly flow= (1.4+ 1.22+0.94+0.71+0.51+0.39+1.02+2.36)/ 7

    =1.22

    With a factor of Safety=1.5

    Design Discharge= 1.83 cumec.

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    Preliminary Design Of side intake with Weir and Canal for Nyam Nyam khola

    Design discharge(Qd)=1.5*1.22=1.83 cumec

    Design Parameters

    In Nyam Nyam khola = River bed level for the weir= 1121 [amsl]

    Weir Crest level (hr)= 1123.3 [amsl]

    Design flood level= 1127 [asml]

    Sectional Area Required (A)= Q/v

    Approach Velocity(Va)= 1.5 [m/s]

    Ie ; Area(A)=1.83/1.5=1.22 [m2]

    Now,

    For the opening of the canal= A=W*H

    Fixing the H value of the opening of the orifice=1123.3-(1121+0.6+0.3=1120.9)=1.4m from 1123.3 m

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    Take height of the opening H as 1m

    Now for the width (W)=1.22/1 m = 1.22 m

    We take approximately = 1.5m for the width of the opening of the orifice

    hr is the water level for normal operation of the intake for the operation 1123m

    now

    Flood water level 1127m

    Normal water level 1123 m

    0.75m 0.75m

    H= 1m

    River bed level 1121 m

    Thickness of wall on each side = 0.3m

    Therefore the total width of the orifice opening is 0.3+0.75+0.75+0.3 =2.1m

    For the approach canal design we use mannings design formulae

    Q=1/n (R)^2/3 S^(1/2)

    Where,

    Qd= design discharge

    n= mannings roughness coefficient

    R=hydraulic radius

    S=slope of the canal

    Design discharge (Qd) = 1.22 m/s

    Required discharge (Q) = 1.3 * 1.22 = 1.586 m/s

    Orifice

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    Channel type: Masonry and concrete

    Stone masonry in cement mortar using split stone, 1:4 cement and

    sand mortar

    Therefore, maximum velocity = 2m/s, for mannings co-efficient (n) = 0.02

    Side Slope (N) = 1.5 (1V:1.5H)

    We choose, Velocity (v) = 1.8 m/s

    Cross- sectional area (A) = Q/v = 1.58/1.8 =0.88 [m^2]

    I.e the channel bottom width B= 1m

    I.e . critical depth of water (yc)

    A=(B+Nyc)yc;

    0.88=(1+.5.yc)yc; T=B+2*yc*N

    Solving the quadratic equation: N*yc B

    yc =0.661m

    Top width yc

    (T)=(B+2.N.yc);

    =(1+2*0.5*0.661) B

    =2.661m

    Critical velocity (vc) = (A*g/2)1/2

    = (0.88*9.81*0.5)^(0.5)

    =2.077 m/s

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    2.077m/s> 1.8m/s (which is OK)

    Wetted perimeter (P) = B+ 2.yc ((1+N2))

    =(1+2.066(1+.5^2)^(0.5))

    =1.148m

    Hydraulic radius (R) = A/P = 0.88/1.148

    = 0.765m

    Now,

    S = 8% gradient

    D = 11 RS

    = 11*0.765*0.08=0.672mm

    i.e. particles larger than 0.6752mm would settle in the approach canal.

    Provide 60cm freeboard on the canal.

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    Mailun Khola Hydropower Catchment Calculation

    The following image shows the catchment of MAilun Khola.

    The red shaded part indicates the area above 5000 amsl

    The blue shaded part indicates the area from 3000-5000 amsl

    The green shaded area indicates the area below 3000 amsl

    WECS method to calculateinstantaneous peak flood

    Project Name Mailung

    Input

    Area of basin: 73 sq. km

    Area below 5000m: 65 sq. km

    Area below 3000m: 11 sq. km

    monsoon wetness index: 1600

    hydrological region: 3

    calculating flood discharge of return period of 2 and 100 years

    Q(2)= 16.6 cumec

    Q(100)= 90.7 cumec

    calculating the flood peak in different return periods

    x= 0.728927021 B 2.81200843

    Enter return period: 1000 standard variate = 3.09

    Q(n)= 158.3

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    Column1 Column2 Column3 Column4 Column5 Column6 Column7 Column8

    wecs method to estimate flow duration curve

    calculating the discharge for specified probability of exceedence

    Q(0%)= 23.60 cumec

    Q(5%)= 13.25 cumec

    Q(20%)= 7.62 cumec

    Q(40%)= 2.12 cumec

    Q(60%)= 1.03 cumec

    Q(80%)= 0.60 cumec

    Q(95%)= 0.38 cumec

    Q(100%)= 0.3171 cumec

    Plotting the flow duration curve

    x y0 23.60

    5 13.25

    20 7.62

    40 2.12

    60 1.03

    80 0.60

    95 0.38

    100 0.32

    Estimating the long term Average monthly flowEnter the month(1-12)= 12

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    Therefore.

    Also WECS and MIP method for flood estimation was used to calculate the discharge

    C= 0.001485

    A-1 0.9536

    A-2 0

    A-3 0.3607

    Monthly average flow is estimated as:

    Q(avg)= 1.27 cumec

    Month C A-1 A-2 A-3 FLOW(Cumec)

    January 0.01423 0 0.9777 0 0.86

    February 0.01219 0 0.9766 0 0.73

    March 0.009988 0 0.9948 0 0.65

    April 0.007974 0 1.0435 0 0.63

    May 0.008434 0 1.0898 0 0.81

    June 0.006943 0.9968 0 0.261 3.43July 0.02123 0 1.0093 0.2523 9.37

    August 0.02548 0 0.9963 0.262 11.44

    September 0.01677 0 0.9894 0.2878 8.85

    October 0.009724 0 0.988 0.2508 3.88

    November 0.00176 0.9605 0 0.391 1.94

    December 0.001485 0.9536 0 0.3607 1.27

    Annual Average

    flow = 3.65 cumec

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    Conclusion

    We were involved in various tasks in assisting our supervisor at the host organization.

    We learned the methodology accepted in the organization for carrying out different

    activities. We learned professional behavioral characteristics.

    This internship Program has been an entirely different experience of learning, the need

    to be inquisitive was felt, along with technical know how, we have learned more about

    the practical challenges that will be faced during the development of hydropower

    projects. HEP in Nepal have to be custom designed to the topography, the hydrology

    and the social setup of the country.

    We as engineers have much to learn about the principles of risk analysis and resource

    mobilization. Also, a need for an innovative flushing system that suits the type of

    sediment Nepali River basis carry is immense. There is a huge demand for geo

    technical engineers to carry out larger projects.

    Now that the political environment is less fragile and agreements less volatile,

    companies like MKHP are looking to complete their projects and reap benefits. Large

    Hydel projects are very difficult in area with no road access. This has forced us to

    adopt small multiple projects and move upwards later on to reach inaccessible places.

    The fact that only a 5MW project had to construct 11 km of hill road is astounding.

    The internship program was useful in providing good motivation and boosting up our

    confidence prior to leaving the university.

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    Bibliography

    -Mosonyi, E. 1987, Water power Development

    -Warnick, CC, (1984),Hydropower Development

    - BPC Hydroconsult. (2009). Civil Works Guidelines for MICRO-

    HYDROPOWER IN NEPAL.Kathmandu: Practical Action Nepal Office.

    - Department of Electricity Development, Ministry of Water Resources,

    Government of Nepal and United States Agency for International Development

    Mission to Nepal. (2001). Guidelines for the Feasibility Study of PROR and

    ROR Hydropower Projects (10-100 MW).Kathmandu: METCON Consultants.

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    Annex A: Pictures

    Catchment area of Mailun Khola

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