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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