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PRESENTATION ON

Bramhayani Hydropower Project – 36.50MW

(Sindhupalchok, Nepal)

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Presented by :

Narayan Poudel, CA

(Financial Analyst)

And

Er. Subash Chandra Baral – Technoquarry Consults Pvt. Ltd

May 2022

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Project Location :

28o 01’ 24″ N to 28o 04′ 16″ N Latitude

85o44′38″ E to 85o47′30″ E Longitude

Location:

Jugal Rural Municipality,

Sindhupalchowk District, Bagmati Pradesh

Bramhayani HEP

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Licensed area VDCs (Golche and Gumba)

Project Location :

Golche

Gumba

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PROJECT LOCATION :

Road Access

Kathmandu- Balephi = 72 Km

Balephi – Kartike = 1 8 Km

Kartike – Nyasem = 15 Km

Nyasem – Tembathan = 6 Km

Tembathan - Ladanbesi = 7 Km

Access Road required constructing for

Project Area is 15 Km

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PROJECT UNDER BALEPHI BASIN :

Bramhayani HPP 35.47 MW

Upper Bramhayani HPP 15.15 MW

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TECHNICAL INFORMATION

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Project Location :

28o 01’ 24″ N to 28o 04′ 16″ N Latitude

85o44′38″ E to 85o47′30″ E Longitude

Location:

Jugal Rural Municipality,

Sindhupalchowk District, Bagmati Pradesh

Bramhayani HEP

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PROJECT UNDER BALEPHI BASIN :

Bramhayani HPP 35.47 MW

Upper Bramhayani HPP 15.15 MW

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Licensed area VDCs (Golche and Gumba)

Project Location :

Golche

Gumba

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Project Components Overview- Topo Map

28° 04' 16" N

85° 47' 30" E

28° 01' 24" N

85° 44' 38" E

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Headworks

Headrace Pipe

Headrace Tunnel

Surge Tank

Powerhouse

Headworks

Headrace Tunnel

Underground Powerhouse

Underground Surge Tank

Underground Penstock

Connecting

Arrangement

Overall Project Components Overview- Google Map

Upper Brahmyani HPP

Brahmyani HPP

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Connecting Alignment from Upper Brahmyani (D-1.8m, L=863m)

Weir, 22m long, EL. 2623.50 m)

Desander: Underground, 2Nos. (59m X 7m X 9.97m)

Brahmyani headrace Tunne Junction (EL.2616m)

Powerhouse(EL.2632.50m)

Headrace tunnel ( size= D-shaped, 3.2 X 3.5 m, L=5785m)

Adit -1( size= D-shaped, 3.2 X 3.5 m, L=235m)

Adit -2( size= D-shaped, 3.2 X 3.5 m, L=253m)

Surgetank (Underground, 5m H=37 m)

Horizantal Pressure shaft

Size= 3.2 X 3.5 m , L=460 m

Incline Pressure shaft

D= 3.5m , L=636 m

Powerhouse (Underground, 54m X15.4m X16.6m)

Turbine Axis= El. 2027.78m

Project Components - Google Map

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Connecting Alignment from Upper Brahmyani (D-1.8m, L=863m)

Weir, 22m long, EL. 2623.50 m)

Desander: Underground, 2Nos. (59m X 7m X 9.97m)

Brahmyani headrace Tunne Junction (EL.2616m)

Powerhouse(EL.2632.50m)

Headrace tunnel ( size= D-shaped, 3.2 X 3.5 m, L=5785m)

Adit -1( size= D-shaped, 3.2 X 3.5 m, L=235m)

Adit -2( size= D-shaped, 3.2 X 3.5 m, L=253m)

Surgetank (Underground, 5m H=37 m)

Horizantal Pressure shaft

Size= 3.2 X 3.5 m , L=460 m

Incline Pressure shaft

D= 3.5m , L=636 m

Powerhouse (Underground, 57.00m X12.89m X17.47m)

Turbine Axis= El. 2027.78m

Detailed Project Components - Google Map

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Upper Brahmyani Powerhouse EL. 2632.50

Upper Brahmyani tailrace

Connecting alignment (D=1.8 m , L=863m

Brahmyani Headrace Connection. EL. 2616m

Brahmyani Headworks

Project Components - Google Map- Junction Details

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Underground Powerhouse( size= 57.00m X 12.89m X 17.470m, Turbine axis=EL.2027.78 m

Switchyard

= 50 m X 30m

Tailrace, D Shaped, 3.2 X 3.5 m,

L= 343m

Main Access tunnel, D Shaped,

6.0 X 5.0 m, L= 320m

Adit-4, D Shaped, 3.2 X 3.5 m,

L= 248m

Adit-3, D Shaped, 3.2 X 3.5 m,

L= 305m

Surgetank= D=5m, H=37m

Inclined pressure shaft-2

D=3.5m, L=355m

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Inclined pressure shaft-1

D=3.5m, L=281m

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Project Components Profile- Google Map

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Underground Powerhouse( size= 57.00m X 12.89m X 17.47m, Turbine axis=EL.2027.78 m

Switchyard

= 50 m X 30m

Tailrace, D Shaped, 3.2 X 3.5 m,

L= 343m

Main Access tunnel, D Shaped,

6.0 X 5.0 m, L= 320m

Adit-4, D Shaped, 3.2 X 3.5 m,

L= 248m

Adit-3, D Shaped, 3.2 X 3.5 m,

L= 305m

Surgetank= D=5m, H=37m

Inclined pressure shaft-2

D=3.5m, L=355m

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Inclined pressure shaft-1

D=3.5m, L=281m

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Project Components - Google Map

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Adit -1( size= D-shaped, 3.2 X 3.5 m, L=235m)

Adit -2( size= D-shaped, 3.2 X 3.5 m, L=253m)

Headrace Tunnel( size= D-shaped, 3.2 X 3.5 m, L=5785m)

Inclined pressure shaft-2

D=3.5m, L=355m

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Inclined pressure shaft-1

D=3.5m, L=281m

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Project Components Profile- Google Map

2000m

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1900m

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1785m

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PROJECT LAYOUT – CONTOUR MAP

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PROJECT GROUND PROFILE

Headrace tunnel

Underground Desander

Feeder Tunnel

Weir/Intake & Gravel Trap

HRT Adit-1

HRT Adit-2

Surge Shaft

Pressure Shaft

Powerhouse

Tailrace canal

HRT Adit-3

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PROJECT STRUCTURES

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Headworks

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Headworks

asasasasasasasasasass

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Crest EL. 2623.50m, L=22m

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Headworks

asasasasasasasasasass

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Desander Basin

asasasasasasasasasass

H

Desander= Underground, 2 bays,59.0m, 7.0m X 9.97m

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Desander Basin

asasasasasasasasasass

Desander= Underground, 2 bays,59.0m, 7.0m X 9.97m

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Pressure Shaft Alignment

asasasasasasasasasass

Surgetank, D=5.0m, H=37m

355m

281m

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Powerhouse layout

Main Access Tunnel= Size= 5.0m X 6.0 m, H=319m

Powerhouse= Size 53.0 X 15.40.0 m, X 16.64m

Tailrace= L=343m, 3.2 *3.5m

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Powerhouse layout

Turbine Axis= EL. 2027.78

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Powerhouse Layout

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Technical Sailent Feature

Intake

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Lagan Khola

1. Lagan Khola

  • Orifice type side intake.
  • 2 nos. opening size of (2.20m x 2.20m).
  • Inverted Level 2620.70 masl.

2. Cascade arrangement to tap tail water from Power House of Upper Bramhayani HEP

Gravel Trap

1. Lagan Khola

  • Size; 1 x (5.0m x 8.60m to 3.95 x 5.95m)
  • water level; 2623.41 masl

Settling Basin

  • Underground Type.
  • 2 nos. of bay with each chamber size (59.0m x 7.0m x 9.97m) (LxWxH)

Headrace Tunnel

  • Inverted D-shaped Pressurized type.
  • size; (3.2m x 3.5m)
  • length; 5785 m

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Technical Sailent Feature

Adit Tunnel

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1. Adit Tunnel - I

2. Adit Tunnel - II

3. Adit Tunnel - III

4. Adit Tunnel - IV

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1. Adit Tunnel-I

  • Inverted D-shaped pressurized
  • Size; (3.2m x 3.5m)
  • Length; 234.35 m

2. Adit Tunnel-II

  • Inverted D-shaped pressurized
  • Size; (3.2m 3.5m)
  • Length; 253.0 m

3. Adit Tunnel-III

  • Inverted D-shaped pressurized
  • Size; (3.2m x 3.5m)
  • Length; 305 m

4. Adit Tunnel-IV

  • Inverted D-shaped pressurized
  • Size; (3.2m x 3.5m)
  • Length; 248.20 m

Surge Shaft

  • Underground Circular Concrete
  • Diameter; 5.0 m
  • Height; 37 m
  • 2623.50 masl water level

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Technical Sailent Feature

Horizontal Shaft

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1. Horizontal Shaft – I

2. Horizontal Shaft – II

3. Horizontal Shaft - III

1. Horizontal Shaft-I

  • Inverted D-shaped pressurized
  • Length; 55.50 m & Size; (3.2m x 3.5m)

2. Horizontal Shaft-II

  • Inverted D-shaped pressurized
  • Length; 57.4 m & Size; (3.2m x 3.5m)

3. Horizontal Shaft-III

  • Inverted D-shaped pressurized
  • Length; 26.0 m & Size; (3.2m x 3.5m)

Inclined Shaft

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1. Inclined Shaft - I

2. Inclined Shaft - II

1. Inclined Shaft-I

  • Rectangular Type.
  • Diameter; 3.5m & Length; 282.0 m

2. Inclined Shaft-II

  • Circular Type.
  • Diameter; 3.5m & Length; 356.0 m

Powerhouse

  • Underground Type.
  • Size; (57m x 12.89m x 16.64m) (L x B x H).

Switchyard

- Size; (50m x 30m) (L x B)

Tailrace Canal

  • Underground.
  • Length; 250.0 m
  • Size; (3.20m x 3.5m) (B x H)

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Technical Sailent Feature

Turbine

  • 3 Nos. Turbine Units
  • Horizontal Pelton Type.
  • Rated Output; 12.17 MW X 3 Units.

Generator

  • 3 Nos. of generator.
  • Horizontal 3-phase AC & 15,686 kVA each capacity

Transmission Line

  • 132 Kv Single Circuit Line
  • 15 km length Upto Pangtang S/S from Switchyard.

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GEOLOGY

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Geology

  • Project Lies in the Higher Himalayan rock units of Eastern Central Part of Nepal.

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  • The area represents by the high grade to the crystalline Precambrian metamorphic rock units.

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  • Banded gneiss foliated micaceous gneiss, biotite schist, mica containing quartzite are the prominent lithology in the project area.

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  • The granite intrusion in the gneiss is also frequent in this area.

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Geology

  • Geologically, weir axis area belongs to Formation II of Higher Himalayan, banded gneiss >> schist can be observed.

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  • No any slide in upstream of weir axis bedrocks are exposed on right bank and riverbed also.

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  • Geologically good location for the weir axis.

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WEIR AXIS AREA�

Weir Axis

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Geology

Outlet of Sand Flushing:

  • Underground Settling Basin lies on right bank, under strong mountain of gneiss

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Geology

  • Left bank of the river has a vertical slope. proposed inlet portal area belongs to the Formation II of Higher Himalaya.

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  • Exposed rock has same characters as rock exposed at weir axis area.

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  • Stable on hill slope.

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INLET PORTAL AREA�

Inlet Portal

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Geology

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  • Alignment belongs to rocks of the Formation II of Higher Himalaya. length of tunnel shall be less than 1.1 km.

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  • Thick and massive beds of banded gneiss, less jointed rocks and schist of Higher Himalaya can be observed.

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TUNNEL ALIGNMENT�

Tunnel Alignment

Rock Class

Class II= 35%

Class III= 35%

Class IV= 20%

Class VI=10%

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Geology

Adit Portal

Surge Shaft Adit Tunnel

  • The Rock in this section are grey to black grey, coarse grain, laminated to thick bedded mica gneiss and grey colour, coarse grained, thick bedded gneiss.

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  • It lies in the grey to black colour, coarse grained, moderately weathered rock of mica gneiss.

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  • The main rock type in this section are mica schist, mica gneiss/foliated gneiss and quartzite intercalation with banded gneiss.

Surge tank

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Geology

Powerhouse and Penstock

  • The rock type along the inclined shaft and inclined penstock alignment includes massive gneiss with partings of quartzite.

Main Access Tunnel Portal (320m)

Pressure Shaft

Power House 200m Inside

Tailrace Portal

355m

281m

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Geology

  • Design horizontal seismic coefficient ranges from 0.13 to 0.15 (calculated values).

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Seismicity�

Geology

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Geology

  1. Material Sources are beds of Balephi khola
  2. Mucking materials from the tunnel can be used as construction material (Aggregate)
  3. Big boulders along the pipe alignment can be used as construction material
  4. Lab test of construction materials from river bed falls under standard norms

Construction survey material

Geology

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Geology

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  • Far from MCT, negligible effect of the MCT in project area
  • Competent rock types and appropriate orientation of foliation plane for tunnel alignment
  • Free from the any types of the failure
  • Sufficient construction materials can be extracted from riverbed
    • Geology of the project site and surrounding is fairly sound and stable for sub-surface construction and also for the surface structures

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Geology Feature of Project

Geology

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Geology

Risks/Challenges

Fig :- Landslide at the Gang Kharka Kholsi

  • Possibility of Mass wasting along the project area.
  • At the right bank of the langtang Khola, at headwork's area is steep slope and the left bank covers with the rock fall from the upper slope.
  • Old and New Slide, wedge failure, Plane failure, landslide are the common mass wasting observed in the project area.
  • The huge new and old mass slides are dominant along the tunnel alignment area.
  • The most Slides are active near the kholsi area.
  • Block failure is seen at the quartzite band, gneiss band at the bed rock, right bank of the Balephi khola.
  • The movements of soil, loose weathering rock mass by the fluid are also commonly observed in this area.
  • The debris flows, fans observed around the kholsi are the common flows in this area.

Geology

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Hydrology

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Nyamya Masal Khola

A=110.63 KM2,

Qd=4.02 m3/s

Lagan Khola

A=86.08 KM/m2

Qd= 3.93m3/s

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Headworks

Powerhouse

Waterways

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Drainage Distributions In Elevation

<3000m = 1%

3000-5000m = 65%

>5000m= 35%

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Hydrology

Catchment area

Design flood

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196.71km2

7.95 m3/s

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Mean monthly flow

Flow duration curve

Probability of Exceedance %

Nyamya Masal Khola

Lagan Khola

Total

5

57.48

44.92

102.41

10

41.09

31.67

72.76

15

33.43

25.69

59.12

20

27.18

20.84

48.02

25

23.30

18.10

41.41

30

17.52

13.67

31.19

35

11.62

8.96

20.58

40

8.58

6.58

15.16

45

6.62

5.05

11.67

50

5.38

4.10

9.48

55

4.71

3.58

8.29

60

4.05

3.07

7.12

65

3.46

2.50

5.96

70

3.31

2.50

5.81

75

3.07

2.31

5.38

80

2.78

2.09

4.87

85

2.50

1.87

4.37

90

2.46

1.78

4.24

95

2.08

1.57

3.65

100

1.45

1.20

2.65

Month

Discharge (m3/s)

Baisakh (Apr/May)

6.12

Jestha (May/Jun)

17.79

Ashadh (Jun/Jul)

56.89

Shrawan (Jul/Aug)

81.34

Bhadra (Aug/Sep)

66.82

Ashwin (Sep/Oct)

39.02

Kartik (Oct/Nov)

18.69

Mangsir (Nov/Dec)

9.91

Poush (Dec/Jan)

6.82

Magh (Jan/Feb)

5.75

Falgun (Feb/Mar)

4.52

Chaitra (Mar/May)

4.79

Average

26.03

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Hydrology

Monthly hydrograph at the proposed intake site

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Month

Discharge (m3/s)

Percentage of Snow Contribution (%)

CAR Method

Measured Mean Monthly Discharge

Snow Contribution Discharge

January

4.02

4.33

0.31

7.16

February

3.49

5.30

1.81

34.18

March

3.34

4.23

0.89

20.95

April

3.77

3.74

-0.03

-0.80

May

5.37

-

-

-

June

16.16

-

-

-

July

42.03

-

-

-

August

51.68

-

-

-

September

36.69

-

-

-

October

16.07

19.88

3.81

19.16

November

7.9

12.52

4.62

36.90

December

5.36

7.39

2.03

27.47

Calculated Vs Measured flow

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Hydrology

Flow Duration Curve at the proposed intake site

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Power and Energy

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Power and Energy

Power and Energy

Estimated energy (GWh) for different months

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Power and Energy

S.N.

Months

Days

Flow (m3/s)

Net head (m)

Generation capacity (MW)

Energy (GWh)

Monthly

Design

Dry

Wet

1

Baishakh

31

6.12

3.060

550.805

14.43

10.632

 

2

Jestha

31

17.79

7.950

539.425

36.73

13.089

13.962

3

Ashadh

31

56.89

7.950

539.425

36.73

 

27.051

4

Shrawan

32

81.34

7.950

539.425

36.73

 

27.924

5

Bhadra

31

66.82

7.950

539.425

36.73

 

27.051

6

Ashwin

31

39.02

7.950

539.425

36.73

 

27.051

7

Kartik

30

18.69

7.950

539.425

36.73

 

26.179

8

Mangsir

29

9.91

4.955

547.668

23.24

8.283

7.731

9

Paush

30

6.82

3.410

550.339

16.07

11.456

 

10

Magh

29

5.75

2.875

551.031

13.57

9.348

 

11

Falgun

30

4.52

2.260

551.679

10.68

7.611

 

12

Chaitra

30

4.79

2.395

551.551

11.31

8.064

 

Maximum power generation (MW)

36.73

 

 

Total annual gross seasonal energy (GWh)

68.484

156.950

Total outage energy (@ 4 %)

2.739

6.278

Total annual marketable seasonable energy after outage (GWh)

65.744

150.672

Total annual marketable energy after outage (GWh)

216.416

Percentage of seasonal energy with respect to total energy (%)

30.379

69.621

Plant factor

67.267%

Input Parameters

Symbol

Value

Unit

Design discharge

Qd

7.95

m3/s

Gross head

Hg

552.72

m

Turbine efficiency

 

90.00

%

Generator efficiency

 

97.00

%

Transformer efficiency

 

99.00

%

Overall efficiency

Ƞ

86.427

%

Outage

 

4

%

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Power and Energy

Power and Energy

Energy Table as per PPA

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Generator Specification

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Particular

​

Specification

No of Units

Three

Generator Type

Horizontal,3ØAC

Rated Capacity

15686 KVA each

Rated Efficiency

95%

Power Factor

0.85 lag

Rated Speed

600 rpm

Frequency

50 Hz

Generation Voltage

11 kV

Insulation Grade

Grade F

Phase Connection

Star- connected

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Grid Connection and PPA Provision

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Grid Connection and PPA Provision

As of PPA

Connection : 220V/132 kV, Single Circuit

Voltage : 132 KV

Length : 15 km

From : Powerhouse

To : NEA Proposed Pangtang Sub-Station

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Transmission Line Status

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Connection Arrangement

Switchyard of Brahmayani HEP

NEA Proposed Substation;

Pangtang S/S

15 km, 132 KV Single Circuit Line

5 Km, 132 KV Single Circuit Line

Nyamya masi Khola

Lagan Khola

Switchard of Upper Brahmayani

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Connection Arrangement

Nyamya masi Khola

Lagan Khola

Switchyard of Brahmayani HEP

16 km, 132 KV Single Circuit Line

NEA Proposed Substation;

Pangtang S/S

Headrace Tunnel, Length = 6036.50 m

Switchyard of Upper Brahmayani HEP

5 km, 132 KV Single Circuit Line

Headrace Tunnel, Length = 4705.75 m

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Land Acquisition Status

It will be finalized after Completion of Demarcation and it has already been approved from EIA

​

Pvt. Land – Near about 41 Ropani

Government - Minimum

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Technical Conclusion

  • The source of water is very reliable in Nyamya Masal and Lagan Khola, the design discharge has been estimated as 7.95 m3/s including both rivers at 42 percentile exceedence flow at the intake site.

​

  • The proposed project, with gross head 552.72 (535.35 in PPA) m and design discharge of 7.95 m3/s will have installed capacity of 36.73 MW (PPA 35.47 MW) and found to be feasible project from technical, economic and environmental aspects.

​

  • Since it is snow fed river, it has very reliable source of water. 50% downstream release is provided.

​

  • The geological study has shown that there is no such severe geological risks associated with the project except some minor instability which could be taken care during excavation and construction.

​

  • The power generated from the project would be evacuated to the national grid of INPS at 132 kV Pantang Substation.

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  • With negligible impact on physical, biological and aquatic life and limited interference on human life, the project is environment friendly.

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Work Progress

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Survey at headwork's

Discontinuity measurements at proposed adit

Field Photographs Bramhayani

asasasasasasasasasasasasasasassasas

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Gauge being installed

Installed Gauge

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Discharge Measurement @powerhouse (Balephi)

Discharge Measurement @headwork's (Langan khola)

Test pit for construction material @powerhouse area

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Field Photographs of Access Road (Under Construction)

asasasasasasasasasasasasasasassasas

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Project Review site visit

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PROJECT PHOTOGRAPHS

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Headworks Area

Water Flow at Headwroks area at Lagan Khola

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Inlet Portal Area

Inlet Portal

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Adit Tunnel Area

Adit Portal

Downstream

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Geology

Powerhouse and Penstock

Main Access Tunnel Portal (320m)

Pressure Shaft

Power House 200m Inside

Tailrace Portal

355m

281m

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Water flows at headworks

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Thank You !!!!!