Kathmandu UniversitySchool of EngineeringDepartment of Civil and
Geomatics EngineeringDhulikhel, Kavre
Final Report onStudy for Rehabilitation of Mangaltar-Daauney
Micro-Hydropower Project(6.87 kW)
Submitted By:Prateek Nepal (34)Anish Pathak (42)Prajwal Neupane
(63)Aashish Dahal (67)Avinash Mishra (69)
Submitted to:Prof. Dr. Ing. Ramesh Kumar MaskeyDepartment of
Civil and Geomatics Engineering
Date of Submission: 4th January, 2015AbstractDaauney Khola
Micro-Hydropower (6.87 kW) is a project situated at Mangaltar
VDC-5, Kavre as a hydro-power scheme of micro level for rural
electrification. The scheme was chosen by a group of fourth year
students from the Department of Civil Engineering, Kathmandu
University for study. Field based observation and analysis of major
problems existing in the sites were the major key objectives of the
project. This report presents such endeavor.The project has been
out of operation since the August of 2014. The headrace canal has
been buried in a landslide debris and transmission line towers have
been in poor condition. Solutions to improve the present conditions
and restore power generation have been proposed in this report.
AcknowledgementThe team would like to present its humble
gratitude towards the H.O.D. of Civil and Geomatics Engineering Dr.
Prof. Ing. Ramesh Kumar Maskey for his support and provision of an
opportunity to conduct a field project. We would also like to thank
our seniors for helping us collect the necessary preliminary
information about the site. The local helper from Daauney,
Mangaltar-5, Mr. Chandramani Parajuli holds an inseparable position
in our gratitude.
Table of ContentsAbstract2Acknowledgement3Table of Contents4List
of Figures5List of Tables51. Introduction11.1 Background11.2
Objectives12. Methodology23. Gantt Chart24. Description of Daauney
Khola MHP24.1 Salient Features34.2 Hydrology34.3 Scheme Layout54.4
Civil Components65. Observations86. Proposals for Mitigation and
Improvement97. Design97.1 Headrace Canal97.1.1 Alternative 1:
Rectangular Canal Lined With Stone Masonry97.1.2 Alternative 2:
Earthen Canal Lined with Polyethylene Film107.2 Headrace Pipe107.3
Transmission Line128. Cost Estimation128.1 Rate Analysis128.2 Cost
Estimate128.3 Costs Summary139. Conclusion1310. References13
List of FiguresFigure 1 Cross Section of Daaune Khola (10 m
upstream of weir)4Figure 2 Long Term Annual Hydrograph of Daauney
Khola River5Figure 3 General Layout of Daauney Khola MHP6Figure 4
Cross Section for Headrace Canal in Stone Masonry (dimensions in
mm)9Figure 5 Cross Section for Headrace Canal Lined with
Polyehtylene (dimensions in mm)10Figure 6 Submergence Head for
Headrace Pipe11Figure 7 Masonry Structure at Inlet of Headrace Pipe
(dimensions in mm)11
List of TablesTable 1Gantt Chart of Work Schedule2Table 2
Measurement of Cross Section of Daauney Khola4Table 3 Measurement
of Flow Velocity by Float Method4Table 4MIP Monthly Average
Discharge5Table 5 Varying Sections of Penstock Pipe Used8Table 6
Rate Analysis12Table 7 Cost Estimate of Civil Works12
1. Introduction1.1 Background In Nepal, hydropower projects with
installed capacity of up to 100 kW are termed as Micro Hydropower
projects. The average annual precipitation is about 1500 mm, 80% of
which is received during the monsoon season i.e. mid-June to
mid-October. The long unchallenged hydropower potential estimate of
83 GW (out of which 42 GW being estimated as economically
feasible), as performed by Dr. Hari Man Shrestha has yet not been
practically achieved. However, efforts for remote rural
electrification of up to 100 kW have been prioritized for meeting
the electricity requirements. In rural areas of Nepal, Micro
Hydropower projects are mostly linked with the traditional
watermills and irrigation. These projects can be considered as the
most efficient alternative source of energy. The overall efficiency
of such plants depends on individual components of civil works and
electro-mechanical equipments and major social factors. Generally a
flat 50% overall efficiency is adopted while designing such MHP,
irrespective of its size.The Dauney Khola MHP is a project situated
at Mangaltar VDC-5, Kavre as a hydro-power scheme of micro level
for rural electrification. With an intention to deliver practical
and field based experience of the problems that have to be tackled
in Hydropower projects, a provision of academic project is included
in the fourth year first semester of Civil Department, Kathmandu
University. A group of five students was formed to conduct the
project on Daauney Khola MHP, for evaluating the present conditions
of the project and observe alternatives for improvement or
rehabilitation of the same. The report is prepared based on the
knowledge and literature reviews undergone while conducting the
project in Daauney MHP. The scope of our project is as follows: To
assimilate the existing situation of hydropower project and propose
any relevant alternatives for improving its conditions, if
necessary. To learn about practical limitations and possibilities
of existing power project through literature review, consultation
and field review.1.2 ObjectivesThe primary objectives of this
project are as follows: Observe and study the present condition of
the project Propose necessary alternatives or solutions to the
existing problems in the project areaThis project is also intended
to extend our knowledge regarding civil components of such
hydropower schemes, socio-economical aspects of the project and
practical hurdles to be faced in such projects.
2. MethodologyMethodologies followed to achieve the intended
goals are as follows: Literature review: Relevant literatures of
Micro hydropower guidelines, standards and text books were
reviewed. Google maps and information from REMREC office, Dhulikhel
was also used to access the location and necessary hydrological
data of the projects. Consultation: Suggestions and advice of our
seniors and department faculties, regarding visit to the site,
procedures and relevant alternatives for the project were sought
when needed. Site Visit and public communication: Forming a cordial
relation with the local people of the project area was an essential
part of the project to gain access to the power house and
understand the existing problems and possible solutions. Site
visits, preferably during Fridays, were performed. Design: Based on
our survey and requirements designing of structures for improving
the condition of the project were done. 3. Gantt ChartTable 1Gantt
Chart of Work ScheduleDesk Study
Reconnaissance
Faculty Consultation
Field Visit and interaction with the locals
Discussion on upgradation alternatives
Design works
Economic analysis and cost estimation
Report preparation
MonthSeptemberOctoberNovemberDecemberJanuary
4. Description of Daauney Khola MHPDaauney Micro Hydropower
plant (MHP) lies in the Central Development region of Nepal at
Daauney, Mangaltar-5, Kavre. The project is registered under
District water resource committee and was established in the year
2064 B.S. The project is locally popular as Shree Daauney Khola
Teshro Laghu Jal Bidhyut Aayojana. The installed capacity of the
plant is 6.87 KW and at the present, it benefits about 74
households of the area.Travel route: It is a fair bus travel of
about two and a half hours if one travels from Banepa Bus Park in a
bus to Nepalthok. The travel route sequentially passes from
Dhulikhel towards Chaukot, Patalikhet, Bhakundey and Magaltar. 4.1
Salient FeaturesSourceDaauney Khola and
PinthalipakhamulLocationMangaltar VDC, KavrepalanchowkDesign
Discharge20 lpsGross Head70 mOverall efficiency (as stated by
manufacturers)50%Installed capacity6.87 kWDiversion
structureTemporary weir (Gabion Boxes)Intake typeOrifice Type, Side
intakeTotal Canal length1379mTotal beneficiary householdsproposed:
69currently: 74TurbinePeltonGeneratorInduction type, 10 kW,
3-phase, 380 voltsTotal project costRs. 2334663.54Cost per kWRs.
339834.584.2 HydrologyThe main source of water for the scheme is
Daauney Khola and Pinthalipakha Mul. The scheme was designed using
MIP method for flow prediction. As per the guidelines set by
AEPC/ESAP, only 85% of the minimum acceptable flow should be
considered. The design discharge at the turbine is taken as 20 lps
for which the discharge in the river exceeds the required flow of
24.94 lps for 11 months. During our visit to the river site on 26th
December, 2014 the flow measurement of stream performed by simple
area-velocity and float method was found to be 61 lps. The
following parameters were taken in consideration for flow
measurement.Correction factor for discharge = 0.85 Flow Distance =
5.00 mMIP Region = Region 3
Table 2 Measurement of Cross Section of Daauney KholaRiver Cross
Section
PositionWidth (cm)Depth (cm)Area (m2)
00
14570.016
245110.041
34580.043
44500.018
Area of stream0.117
Figure 1 Cross Section of Daaune Khola (10 m upstream of
weir)Table 3 Measurement of Flow Velocity by Float MethodTime
Measurement
ReadingsArea 1Area 2Area 3Area 4
0.016 m20.041 m20.043 m20.018 m2
18.27.98.18.6
28.47.78.08.4
38.28.08.28.5
Average Time (sec)8.37.98.18.5
Velocity (m/s)0.600.640.620.59
Discharge (m3/s)0.0100.0260.0260.011
Total Discharge (m3/s)0.072
Corrected Discharge 0.061 m3/s
Table 4MIP Monthly Average DischargeMonthRegion 3
CoefficientsMeasured Flow, l/sCorrected Flow for mid-month,
l/sMid-monthly Flow in River, l/sFlow towards turbine, l/s
January2.7149.0724.94
February1.8834.0424.94
March1.3824.9924.94
April1.0018.1116.30
May1.8834.0424.94
June3.1356.6824.94
July13.54245.1824.94
August25.00452.7024.94
September20.83377.1924.94
October10.42188.6924.94
November5.0090.5424.94
December3.756167.9167.9124.94
Figure 2 Long Term Average Annual Hydrograph of Daauney Khola
River4.3 Scheme LayoutThe intake lies on the left bank of Daauney
Khola. Water enters through the intake structure, which is
immediately followed by a gravel trap. A forebay is placed at a
chainage of 1379 meters from the intake. A flushing arrangement is
provided in forebay tank for flushing of sediment deposited.A fine
trash rack is placed at the forebay to stop debris from entering
the penstock. The water is then conveyed via HDPE penstock to
powerhouse to generate electricity. The powerhouse is placed at
suitable location from high flood water level. The water is then
let off to the river again via tailrace canal. The water from the
tailrace can be used to irrigate fields near the powerhouse
site.
Figure 3 General Layout of Daauney Khola MHP4.4 Components4.4.1
Diversion Weir A diversion weir is required at the intake only if
adequate flow cannot be diverted towards the intake during low flow
season. This helps to check the water flow and small storage is
provided while diverting desired amount of water to intake. Gabion
boxes are provided to divert the water towards the intake. The
length of the gabion weir is 2.7 meters and its crest is 0.5 meters
from the river bed.4.4.2 IntakeA rectangular orifice type, side
intake has been constructed in the plant. A wing wall is extended
to both sides of the intake to protect from flood. A trash rack is
placed at the opening of the orifice to protect debris from
entering the headrace canal. The intake structure is made up of
stone cement masonry.The orifice at intake helps in regulating the
flow in the canal. The complete checking of water is sometimes
necessary in case of maintenance of canal as well as other
structures. A wooded stop log is installed at the entrance of canal
at orifice in intake. This gate is lifted manually and slides in
the slots at the wall of the canal. The size of stop-log is 900 mm
X 1000 mm.A coarse trash rack of 900mm x 1200mm is placed at the
intake with spacing of 50 mm for vertical bars.4.4.3 HeadraceThere
is a trapezoidal shaped earthen headrace canal. Its top width is 90
cm, bottom width is 70 cm and height is 30 cm. The total length of
the headrace canal is 1379 m. The canal length is very long and is
in a landslide prone area. The design bed slope of the headrace
canal was 1 in 50 as stated in the DPR.4.4.4 ForebayThe design
report shows that the forebay is at a chainage of 1+379 m from the
intake. It is a forebay cum desilting basin. Specifications of
forebay: Width of basin109 m Total length 3.6 m Height 0.9 m Slopes
at tapered entry1:2 vertically and 1:5 horizontally Slope of
settling length1:50A fine trash rack is placed before the penstock
pipe at the end of forebay. The spacing between bars of trash rack
is 29 mm. A flushing cone is incorporated in the structure for
spilling excess water and to flush out debris during cleaning
process. A flushing pipe of 140 mm diameter has been provided.The
forebay is constructed in stone masonry. The floor is provided with
PCC and the inner surface has been plastered.4.4.5 PenstockA HDPE
penstock is used for conveyance of water from forebay to the
powerhouse. As per the data obtained from DPR of Daune Khola, the
total length of penstock is 115 m and the external diameter of
penstock is 125 mm. To optimize the cost, the thickness of penstock
has been varied along its length. A vent pipe of internal diameter
16 mm is provided at the starting of the penstock pipe. The profile
of the penstock is mostly straight and two bends have been provided
to follow the ground profile. The thickness of penstock has been
varied along its length to optimize the cost.Table 5 Varying
Sections of Penstock Pipe UsedHead RangeTypeDiameter (mm)Thickness
(mm)Rating (kgf/cm2)Length (m)
0~11.61HDPEOD 1253.92.524
11.61~43.81HDPEOD 1258.96.063
43.81~70.00HDPEOD 12514.110.028
4.4.6 TurbineA Pelton type turbine is used for this scheme. The
detailed project report states that the turbine operates under a
gross head of 70 m. The net head is 65.07 m. The turbine was
designed for the rotation of 750 rpm. 4.4.7 GeneratorAccording to
the detailed project report, an induction type generator of
capacity 10 kW, 3 phase, 50 Hz is installed with the rated speed of
1500 rpm. 4.4.8 TailraceThe water from the powerhouse can be
conveyed to the culvert of the highway and then to Roshi Khola via
an open canal at a distance of 10 m from the powerhouse. The canal
is an earthen canal with the top width of 76 cm, bottom width of 30
cm and depth of 26 cm.5. ObservationsBased on the site visits and
communication with the local people we observed the following
points relevant to our purpose of rehabilitating the scheme. The
headrace canal is buried in landslide debris at around 500 meters
from the intake site. The general hill slope in this region is
steep and this area is prone to landslides and erosions. The water
entry into the canal has been stopped by closing the orifice at the
intake. The portion of the canal that is buried in the debris is
around 20 meters long. The portion of the headrace canal at around
400 meters to 800 meters from the intake site lies in landslide
prone area as the ground is steep in this place. Three of the
transmission line towers have fallen and the wires are sagging. The
transmission wires were easily within the reach of a person
standing on the ground at some places. The local personnel claimed
that only 3.5 kW of power was being produced while the project was
in operation. The local people are distressed at the lack of power
source at present and are willing to invest in the rehabilitation
of the hydropower scheme.6. Proposals for Mitigation and
Improvement The earthen headrace canal is prone to seepage
problems. Construction of a stone masonry canal is proposed from
intake to the distance of 400 meters and between the distances of
800 meters to 1379 meters. Between the distances of 400 meters and
800 meters from the intake, use of HDPE pipe for headrace is
proposed for avoiding problems from landslides and erosions. The
transmission line towers need to be replaced and proper ground
clearance for the wire needs to be reestablished. The decreased
power generation could be a result of excessive leakages at joints
and turbine casings. The equipment at the powerhouse need to be
checked for consistency and all leakages should be identified. 7.
Design7.1 Headrace Canal7.1.1 Alternative 1: Rectangular Canal
Lined With Stone MasonryA lined headrace canal is proposed to
replace the existing earthen canal so that the problem of seepage
loss can be avoided. A rectangular lined canal has been designed
for micro-hydropower scheme. The bed slope of the canal is proposed
to be kept 1 in 50 considering the bed slope of the existing canal.
The width of the canal is taken as 300 mm considering the width of
the existing canal to reduce the cost of excavation. The canal is
to be lined with stone masonry in 1:6 cement sand mortar. The
section of the canal designed as per ITDG guidelines for design of
micro-hydro projects in Nepal is as shown below.
Figure 4 Cross Section for Headrace Canal in Stone Masonry
(dimensions in mm)7.1.2 Alternative 2: Earthen Canal Lined with
Polyethylene FilmThin synthetic membranes can be used effectively
to reduce excessive seepage in earthen canals. Polyethylene films,
apart from being easily available, has various other advantages.
Such films can reduce the seepage to zero in all types of soils and
they provide a very dependable seal. The relative cost of
polyethylene is very low compared to Polyvinyl Chloride and Butyl
Rubber sheets, which makes it an attractive option. The existing
earthen canal has been redesigned with an accommodation for
polyethylene sheets as seepage control measure.The bed slope of the
canal is proposed to be 1 in 50 considering the bed slope of the
existing canal. The width of the canal has been chosen with
consideration of the dimensions of the existing canal to reduce the
cost of excavation. The following is the section of the headrace
canal designed according to Indian Standard code for design of
Polyethylene lined canals (IS 9696: 1995). A 4.8 m wide and 0.2 mm
thick strip of polyethylene should be used along the length of the
excavated trench in the existing canal. The polyethylene sheets
shall line around 979 meters length of the canal.
Figure 5 Cross Section for Headrace Canal Lined with
Polyehtylene (dimensions in mm)7.2 Headrace PipeA 2.5 kgf/cm sq.
HDPE pipe of 140 mm external diameter and thickness of 4.3 mm is
proposed for use between chainage of 400 meters and 800 meters from
the intake. The pipe should be submerged sufficiently at the inlet
to provide the required head to overcome the head loss in the pipe.
A masonry transition structure should also be built at inlet and
outlet of the pipe for smooth transition into the canal.
Figure 6 Submergence Head for Headrace Pipe (source: Guidelines
for design of MHP, ITDG)The velocity, v, in the pipe for design
discharge of 24.9 lps is 1.8 m/s which is acceptable. For this, a
submergence of = 25 cm must be maintained at the inlet of pipe. The
difference in the level of pipe at the inlet and outlet is 15
meters. The total head loss due to friction and fitting losses is
less than the available head drop so the headrace pipe should carry
the discharge as per design. A mild steel fine trash rack should be
placed at the entry into the headrace pipe. Mild steel flats (5 mm
x 40 mm) at a spacing of 30 cm are recommended to be used for fine
trash rack at the inlet of headrace canal.The profile at the inlet
of headrace canal is shown in figure below.
Figure 7 Masonry Structure at Inlet of Headrace Pipe (dimensions
in mm)7.3 Transmission LineThe original alignment of the
transmission line towers has been disrupted and so new towers need
to be installed along a similar route uphill from the powerhouse.
Hardwood straight wooden poles are suitable for the transmission
line pole. Adopt posts with diameter 125 mm, height 6 m with
minimum ground clearance of 4.5 m maintained for wires. A spacing
of 30 m between poles the poles should be maintained.8. Cost
Estimation8.1 Rate AnalysisTable 6 Rate AnalysisS.N.Description of
WorkUnitQuantityRateTotal
1Earthwork Excavation
LabourUnskilledMD0.7350245
Rate per m3245
2Earth Filling
LabourUnskilledMD0.5350175
Rate per m3175
3Sand Filling
LabourUnskilledMD0.7350245
MaterialSandm31.117101881
Rate per m32126
4Stone Masonry
LabourSkilledMD115001500
UnskilledMD27001400
MaterialStonem31.29901188
Cementbags1.87001260
Sandm30.361710615.6
Rate per m35963.6
8.2 Cost EstimateTable 7 Cost Estimate of Civil
WorksS.N.Description of WorkQuantityUnitRateAmount, NRs.
1Headrace Canal in Stone Masonry
iExcavation31.62m3245.00 7,746.90
iiStone Masonry411.2m35963.60 2,452,232.32
Total of 1 2,459,979.22
2Headrace Canal in Polyethylene Lining
iExcavation971.43m3245.00 238,000.35
iiSand Filling46.2m32126.00 98,221.20
iiiPolyethylene Sheets4699.2m225.00 117,480.00
ivEarth Filling662.66m3175.00 115,965.50
Total of 2 569,667.05
3Headrace Pipe (HDPE)
iExcavation19.04m3245 4,664.80
iiBackfilling12.89m3175 2,255.75
iiiHDPE Pipe 140mm OD/2.5 kgf/cm2400m445.80 178,320.00
Total of 2 185,240.55
Total of 1-3 2,645,219.77
Total of 2-3 754,907.60
8.3 Costs SummaryThe cost of construction of the headrace canal
in stone masonry is more expensive than that for the polyethylene
lined canal. So, construction of polyethylene lined canal is
recommended for the renovation of the canal structure. The cost of
construction of a new earthen canal and installation of HDPE
headrace pipe is estimated to be NRs. 754,907.60. 9. Conclusion The
renovation of the Daaune Khola MHP is desired highly by the local
people. The local are ready to invest in the rehabilitation of this
project as lack of electricity has made difficult their daily
livelihood. Rehabilitation would also support the development of
two agro mills and wood mill that are in the Daune Village. This is
very important for the overall economic development of the village.
Considering the benefits of renovation, it is highly recommended
that the project be rehabilitated and power supply renewed in the
Dauney Village.10. ReferencesCivil Works Guidelines for
Micro-Hydropower in Nepal, ITDGLining of Canals with Polyethylene
Film - Code of Practice, IS 9698, 1995Micro-Hydropower Design Aids
Manual, Pushpa Chitrakar, 2004Wages and Construction Materials
Rate, District Development Committee, Kavre, 2014Detail Project
Report: Daauney Khola Micro-Hydropower Project, Rural and
Alternative Energy Pvt. Ltd., 2008
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