7/30/2019 Tidong

1/162

TIDONG- HEP

TIDONG-I HYDROELECTRIC PROJECT (60 MW)HIMACHAL PRADESH

PRELIMINARY FEASIBILITY REPORT

GENERAL AND DESIGN ASPECTS

LIST OF CONTENTS

Salient Features of the Project 1 - 4

Chapter-1 : Summary I -1 to I - 8

1.1 General Project Features

1.1.1 General1.2 Main Components of The Project

1.2.1 Diversion Dam1.2.2 Desilting arrangement1.2.3 Head race tunnel1.2.4 Surge shaft1.2.5 Pressure shaft1.2.6 Power house1.2.7 Tail race tunnel

1.3 Studies Undertaken1.3.1 Various alternatives

1.3.2 Hydrological studies1.3.3 Initial environmental studies1.4 Cost and Financial Aspects1.5 Recommendations

Chapter -2 : Background Information II -1 to II- 12

2.1 General Information About The River/ Basin/Sub Basin2.2 Power Scenario2.2.1 Source of energy2.2.2 Hydropower potential of Himachal Pradesh

2.2.3 Thermal power potential of Himachal Pradesh2.2.4 Power scenario in India2.2.5 Demand and supply in Himachal Pradesh State2.2.6 Demand and supply in the Northen Region2.2.7 Satluj river hydropower potential2.3 Need Of The Project

7/30/2019 Tidong

2/162

TIDONG- HEP

Chapter-3 : Project area III -1 to III 4

3.1 Introduction3.2 Location And Access3.3 Climate3.4 Geology

3.5 Seismicity3.6 Socio-Economic Characteristics

Chapter-4 : Geology IV -1 to IV -13

4.1 Introduction4.2 Regional Geology4.3 Structure & tectonics4.4 Seismicity & seismotectonics4.5 Geotechnical appraisal

Chapter-5 : Hydrology V - 1 to V 21

5.1 Introduction5.2 Proposal5.3 Catchment Characteristics5.4 Hydrometerological Aspects

5.4.1 Precipitation5.4.2 Record Of Precipitation5.4.3 Stream flow gauging

5.5 Flow Series5.6 Design Flood5.7 Recommendations

Chapter-6 : Conceptual layout Planning VI -1 to VI - 5

6.1 General6.2 Main Components of the project

6.2.1 Diversion Dam6.2.2 Desilting arrangement6.2.3 Head race tunnel

6.2.4 Surge shaft6.2.5 penstock6.2.6 Power house6.2.7 Tailrace tunnel

6.3 Recommendations6.4 List of drawings6.4.1 Location and vicinity map NO:HPSEB/TD/DPR-01

6.4.2 Road and paths NO:HPSEB/TD/DPR-02

7/30/2019 Tidong

3/162

TIDONG- HEP

6.4.3 General layout plan NO:HPSEB/TD/DPR-036.4.4 L-section along WCS NO:HPSEB/TD/DPR-046.4.5 Diversion dam plan NO:HPSEB/TD/DPR-056.4.6 Desilting tank plan and sections NO:HPSEB/TD/DPR-066.4.7 HRT L-section and X-sections NO:HPSEB/TD/DPR-076.4.8 Surge shaft plan and sections NO:HPSEB/TD/DPR-08

6.4.9 L-section along penstock NO:HPSEB/TD/DPR-096.4.10 Power house plan NO:HPSEB/TD/DPR-106.4.11 Single line diagram NO:HPSEB/TD/DPR-11

Chapter-7 : Power And Energy Benefits VII -1 to VII - 29

7.1 General7.2 Power Potential7.2.1 Water availability7.2.2 90% & 50% dependable year flow series

7.3 Flow Duration Curve7.3.1 Design head

7.4 Full reservoir level7.5 Minimum draw down level7.6 Installed Capacity Studies7.7 Unit Size7.8 Recommendations

Chapter-8 : Electro Mechanical Works VIII-1 to VIII-10

8.1 General8.2 Scope8.3 Power House8.4 Mechanical Equipment8.5 Electric Equipment8.6 Transmission of Power8.7 Establishment

Chapter -9 : Environmental Aspects IX -1 to IX -16

9.1 Description of the Project9.2 Description of Environment

9.2.1 Physical Resource9.2.2 Ecological Resource

9.3 Baseline Environmental Status9.3.1 Climate and temperature

9.3.2 Rainfall and snowfall data9.4 Environment Impact Assessment And Evaluation

7/30/2019 Tidong

4/162

TIDONG- HEP

9.4.1 Impact Identification9.4.2 Prediction of Impacts

9.5 R & R Aspects9.6 Environmental Management Plan

Chapter-10: Infrastructure X- 1 to X - 5

10.1 General10.2 Improvement Of Existing National Highway10.3 Buildings10.4 Tele-communication10.5 Construction Equipment

Chapter-11 : Construction planning and Management XI - 1 to XI - 54

11.1 Construction Equipment Planning11.2 Details Of Construction Equipment11.3 Construction Methodology

11.3.1 Diversion tunnel11.3.2 Coffer dam11.3.3 Diversion Dam11.3.4 Desilting Tank11.3.5 Head race tunnel11.3.6 Surge shaft11.3.7 Pressure Shaft11.3.8 Power house complex

11.4 Recommendations

Chapter-12 : Cost estimates

XII -1 to XII - 22

12.1 General12.2 Cost of Civil Works12.2.1 Broad sub head wise provisions for civil works

12.3 Cost of Electromechanical Works12.4 T- Transmission

12.5 Estimated Cost of the Project

12.6 Recommendations

Chapter-13 : Economic evaluation XIII-1to XIII-10

7/30/2019 Tidong

5/162

TIDONG- HEP

13.1 General13.2 Capital Cost Of The Project

13.2.1 Abstract of capital cost13.2.2 Economic justification13.2.3 Capital structure13.2.4 Revenue anticipation

13.2.5 Repayment period13.2.6 Operation and maintenance charges

13.3 Cost Per MW13.4 Interest During Construction13.5 Energy available for sale13.6 Rate Of Depreciation13.7 Calculation Of Tariff

APPENDIX

i) Initial Environmental Studies.

ii) Correspondence with CEA/CWC.

7/30/2019 Tidong

6/162

TIDONG-I HEP

I.1

CHAPTER 1

SUMMARY

1.1 GENERAL PROJECT FEATURES

1.1.1 GENERAL

Tidong-I Hydroelectric Project located in Kinnaur district of Himachal

Pradesh, is a run-of- the river type development proposed to harness

the hydel potential of river Tidong between Charang and Lambar

villages. The project envisages construction of a concrete gravity dam

on the river Tidong just upstream of Daibu bridge for diversion of adesign discharge of 13.45 cumecs, underground desilting arrangement

into a 5.036 km long, 2.60 m finished diameter head race tunnel on the

right bank of Tidong river. The tunnel terminates in a 3.50m diameter

underground surge shaft. The water from surge shaft shall be further

conveyed through one no' 2.10 m diameter, 825m long steel

surface/underground penstock bifurcating to two generating units in an

underground power house at Lambar. A gross head of 550 m is

available at the power station, which shall be utilized to generate 60

MW (2x30MW) of power.

1.2 MAIN COMPONENTS OF THE PROJECT

1.2.1 Diversion Dam

Tidong river carries a lot of run-off and brings down heavy sediments

including pebbles and boulders. The slope of the river at the diversion

site is 1:50.

7/30/2019 Tidong

7/162

TIDONG-I HEP

I.2

A concrete gravity dam has been proposed across Tidong khad to

divert design discharge of 13.45 cumecs. The river bed level atdiversion site is El 3370.00 m.

An intake structure comprising of R.C.C well with two gates is

proposed on the left bank of the river. The first outlet controlled by

valve/gate is provided for sediment flushing channel at the lower level

to flush out the pebbles etc. collected in the trench back to the river.

Second outlet controlled by gate conveys the water in the power

channel.

1.2.2 Desilting arrangement

A conventional type underground desilting arrangement has been

proposed on the left bank of river to exclude silt particles down to 0.20

mm size from the water before it enters the head race tunnel. The

arrangement comprises two parallel compartments each consisting of

chambers 48 m long, 20m wide and 7.10m high (including 3.5 m

hopper portion) .

1.2.3. Head race tunnel

The head race tunnel, from the junction point at link tunnels from

desilting chambers to the main surge tank, is 5.036 km. long and 2.60

m diameter circular in section. The tunnel diameter is based on techno-

economic studies for a discharge of 13.45 cumecs with a flow velocity

of 2.53 m/sec.

7/30/2019 Tidong

8/162

TIDONG-I HEP

I.3

1.2.4 Surge shaft

The surge shaft, located at the intake of the penstock at 5.036 km

from the 0 RD of head race tunnel, will be 3.5 m dia and 108 m high

with a restricted orifice. A 3.00 m D-shaped adit is proposed at El

3350.00 m to approach the bottom of the surge tank to facilitate

construction. The dome of the shaft shall be approached for

construction through a 3.00 m D-shaped adit.

1.2.5 Pressure shaft tunnels

One surface/underground penstock, 825 m long and 2.10 m dia would

take off from the surge shaft. This would be lined with high tensile steel

corresponding to ASTM-A-537 varying in thickness from 12mm near

the penstock intake to 35mm at the power house end. The penstock

will be bifurcated near the power house, and each branch shall feed

one of the two generating units. A spherical valve has been provided in

each penstock branch to enable its closing whenever required.

1.2.6 Power house

An underground power house cavern of internal dimensions (89.50 m x

15.50 m and 32.15m high) would be located about 130m below the

natural surface level. The power house will have an arched roof with

concrete lining and shall house two generating units, each of 30 MW

capacity. The transformer and underground switch yard shall also be

located in one side of the cavern. Shotcrete and rock bolting at

suitable spacing will be provided in these caverns.

7/30/2019 Tidong

9/162

TIDONG-I HEP

I.4

Two utility tunnels taking off from the tail race tunnel shall be provided

to approach the bottom portion of the power house and shall facilitatethe excavation of the cavern. To approach the top of the machine hall

as also the top of transformer gallery and tail race surge chamber, an

adit is proposed to be constructed with its portal at EL. 2900 m. This

adit shall be used for construction of arch portion and other works from

the top.

1.2.7 Tail race tunnel

The tail race tunnel with 2.60 m, circular section, 100 m long will be

provided to carry the discharge from two draft tube tunnels emanating

from the power house.

1.3 STUDIES UNDERTAKEN

1.3.1 Various alternatives

Two potential diversion sites have been identified, one upstream of

Daibu bridge and another downstream of Sdaibu bridge. Keeping th e

overall development of Tidong khad for power development it is

proposed to provide a diversion dam just upsream of the Daibu bridge

and downstream of confluence of Lalanti khad with Tidong khad at an

elevation of 3370 m.

There is possibility of increasing the height of dam, there by increasing

the storage capacity. This aspect shall be explored in detail at the

detailed project report level.

7/30/2019 Tidong

10/162

TIDONG-I HEP

I.5

1.3.2 Hydrological Studies

(a) Hydrology: - Collection of Hydro meteorological data

i) Discharge data of Tidong khad at Thangi.

ii) Discharge data of Baspa river at Sangla.

iii) Discharge data of Bhaba river at Kafnoo

(b) Water availability studies

i) Computation of 90% availability and 50% availabilitydischarges.

ii) Flow duration curve

iii) Power generation in a 90 % and 50 % dependable years

(c) Flood studies

i) Computation of design flood.

1.3.3 Initial Environmental studies

i) Digitisation of maps (toposheets) with permission of SOI.

ii) Satellite imageries as required from NRSA.

iii) Processing of satellite data for the area of interest by the

consultant. The procedure adopted for processing will be: -

a) Multi-spectral LISS(23.5m resolution) and Single Band PAN

( 5.8 m resolution) data.

b) Land use classification for the area will be carried out after

geo-referencing the satellite data.

c) Land use classification consisting of the following:

7/30/2019 Tidong

11/162

TIDONG-I HEP

I.6

1. Vegetation crown, Cover (Tree canopy)

2. Built up areas? Rocky outcrop etc.

3. Agricultural land (Land on which Agriculture is being

practised currently).

4. Vegetation density classification (Low, medium, high).

5. Water bodies

6. Barren land

7. Any of the peculiar land use category, as per local

scenario.

8. Land use pattern.9. Vegetal cover/density

10. Approximate population density.

1.4 COST AND FINANCIAL ASPECTS

The estimate of costs has been prepared in detail to arrive at the total

cost of the project. The estimates are based on the prices prevailing in

March-2004.

The detailed estimate of cost of civil works is based on the conceptual

layout plan and preliminary designs of different components of the

works. The layout of different components have been adopted after

considering various alternatives and most economical layouts have

been adopted. For carrying out preliminary design, detailed analysis of

rates of different items of works have been prepared as per Guidelines

of CWC (Guidelines for preparation of project estimate for river valley

projects- March 1997). The rates for hydraulic gates, hoists and cranes

etc. are based on the prevalent market rates for such works. Apart

from main civil works, the provisions under various other sub-heads

are also based on the Guidelines of CWC.

7/30/2019 Tidong

12/162

TIDONG-I HEP

I.7

Cost of generating plant and equipment is based on current budgetary

prices of plants for similar equipment for other projects

Provisions for other items like establishment, audit and accounts etc.

are as per norms of CEA.

The total cost of the project at December 2003 price level excluding

escalation, IDC and Financing Charges works out as under:

CivilWorks

Rs 183.55 Crore

ElectricalWorks

Rs 68.29 Crore

Transmission

Rs 10.86 Crore

Total Rs 262.71 Crore

The cost per MW of installed capacity works out to Rs. 4.50 Crore (at

March 2004 price level). Thus, the cost per MW for this project is quite

low, making the project very attractive.

1.5 RECOMMENDATIONS

Detailed survey's as per CWC guidelines are to be done before

detailed project report to firm up the layout of various components.

Detailed geological investigations i.e, drill holes at dam site to confirm

the depth to bed rock, drift at various adits and other geological

investigations as per CWC guide lines.

7/30/2019 Tidong

13/162

TIDONG-I HEP

I.8

Construction material surveys to meet the requirement of various

components.

Collection of hydro-meteorological data to firm the hydrology studies.

Data collection and studies for EIA of the project.

7/30/2019 Tidong

14/162

TIDONG-I HEP

II - 1

CHAPTER 2

BACKGROUND INFORMATION

2.1 GENERAL INFORMATION ABOUT THE RIVER/BASIN/SUB-BASIN

Satluj river is one of the principal river of Himachal Pradesh and it divides

the District Kinnaur into two parts. In its passage through Distt. Kinnaur,

the Satluj river crosses three more or less parallel mountain ranges viz.

the Zaskar Mountain, the Great Himalayas and the Dhauladhar Ranges.

Between three mountain ranges lie the subsidiary valleys of varying

dimensions from the narrow glens and ravines of Tidong and Kirang

streams to the sizeable valleys of Spiti & Baspa river. The significant

tributaries streams and rivers that flow into the Satluj river from south or

along its left bank are successively the Tidong, Hogis, Gyamthing,

Baspa, Duling, Sholding, Manglad etc. Likewise those entering from the

north or its right bank are the Spiti River, Ropa, Kirang, Kashang, Pangi,

Choling, Bhaba, Sorang, Kut and Ganvi Khud. In between there are

many seasonal streams that meet the Satluj river and its tributaries. At

Khab it receives the Spiti river where the bed of the stream is still about

2590 meter above the mean sea level.

Tidong khad has its origin in the North Western slopes of great

Himalayas ranges at an altitude of 6740 meters. It mostly flows in South-

Easterly to North- Westerly direction. A number of Nallas join Tidong

Khad upto its confluence with Satluj River, just upstream of Tirung

village in District Kinnaur of Himachal Pradesh.

Catchment of Tidong Khad lies between Latitude 31 2030 N to 31

3330 N and Longitude 78 2210 E to 78 4750 E. The altitude of

Tidong Khad ranges from 2200 meters at its confluence with Satluj river

7/30/2019 Tidong

15/162

TIDONG-I HEP

II - 2

to 6740 meters in the glacier zone. Survey of India toposheet numbers

53 -I/6,53-I/7,53-I/10,53-I/11 and 53-I/15 in the scale 1:50000 cover the

catchment area of the project.

The catchment area above dam site comprises of steep mountains, a

portion of it is covered with forest and major part is under permanent

snow. Total catchment area up to dam site is 497.86 square kilometers .

Catchment area above permanent snow line i.e. El 4200 meters is 418.36

Sq. kilometers respectively. The catchment area plan has been shown in

Figure-1. The average slope of khad up to diversion site is 1:15, and

thereafter it has a steep descent (slope 1:5), making it most lucrative

scheme for hydroelectric potential exploitation.

The permanent snow line is considered variable in this catchment. While

it is considered to be near 3048 meters (10,000 feet) during severe

intensity storms and during winter months, it is considerably higher in

summer months and during low intensity storms. The permanent snow

line for important projects such as Baspa-II HEP (300 MW) and Sanjay

Vidyut Pariyojna (120 MW) has been adopted as 4240 meters (14000

feet). As the weir is to be designed for a return period of 100 years, which

generally occurs during Summer months beginning in July to end of

September and in the absence of any recorded information on snowfall,

the areas below contour 4200 meters has been considered as rainfed

which contribute to flood.

2.2 POWER SCENARIO

2.2.1 Sources of energy

India is endowed with a vast hydropower potential. As per the latest

assessment carried out by the CEA, exploitable hydro potential in India

has been estimated at about 84000 MW at 60% load factor, which can

7/30/2019 Tidong

16/162

TIDONG-I HEP

II - 3

yield an annual power generation of over 440 TWh of electricity and with

additional seasonal energy, the total energy potential is about 600 TWh a

year. Only 14.5% of this potential is under operation and 7.2% of the

potential is under execution. Thus the bulk of the potential amounting to

77.9% is yet to be developed.

About 73% of India's total installed capacity is thermal-based (Table 3.2).

However expansion of this energy source is encountering difficulties

because of the burden it places on the infrastructure for supply (mines)

and transportation (railways) of coal. Considering that the capacity of

Indian Railways to carry coal effectively is limited and additional tracks

are required, and the coal is of low quality and costly to transport over

long distances, it appears logical to develop thermal projects in specific

areas, e.g. coal-based projects in Bihar, Orissa, Eastern Uttar Pradesh

and surrounding areas, and gas-based power near the port belts of

Gujarat and Maharashtra, and place total emphasis on hydropower in

States such as Himachal Pradesh, Punjab, Haryana, Western Uttar

Pradesh and far-East India - the Himalayan belt.

Table 2.2

Share of Hydropower in India's Installed Capacity

Year Total

installed

Capacity

(MW)

Hydropower

Capacity

(MW)

Share of

Hydropower

(%)

1962-63 5801 2936 50.6

1969-70 14102 6135 43.5

1979-80 28448 11384 40.0

1989-90 63636 18308 28.8

1991-92 69070 19189 27.8

1993-94 76718 20366 26.6

In the Northern Region, hydropower is the most suitable source of power

since both thermal/nuclear or other fuel-based source of energy involve

7/30/2019 Tidong

17/162

TIDONG-IHEP

II - 4

carriage of raw material over long distances making the cost of

development uneconomical. There are no thermal-based power projects

in Himachal Pradesh.

2.2.2 Hydropower potential of Himachal Pradesh

Himachal Pradesh along with the States of Jammu & Kashmir and Punjab

form part of the Great Indus Basin. This basin comprises six major rivers,

viz., Indus, Jhelum, Chenab, Ravi, Beas, and the Satluj, and drains a total

area of 1.16 x 106 km2, out of which 0.17 x 106 km2 lies in India. A total of

about 190 hydropower schemes have been identified in the Great Indus

Basin having a firm hydropower potential of 11993 MW at 60% load

factor. according to the CEA in its publication "Hydro Electric Power

Potential of India", December 1988, in various States and river basins in

the country. The total potential in Himachal Pradesh is 11578 MW at

60% load factor, with an installed capacity of 18715 MW.

The Satluj basin in Himachal Pradesh has a hydropower potential of

9443.75 MW, which represents approximately 50% of the likely installed

capacity in Himachal Pradesh. Five schemes in the Satluj are already in

operation with a total installed capacity of 3150.25 MW. The projects with

an installed capacity of 1880.50 MW are under execution or likely to

commissioned in near future. The remaining 4296 MW potential is yet to

be developed.

Besides Nathpa-Jhakri and Baspa II, the following projects in the Satluj

basin have been identified and form part of the river unexploited potential.

Kol Dam 800 MW

Rampur 400 MW

7/30/2019 Tidong

18/162

TIDONG-IHEP

II - 5

Karcham-Wangtoo 1000 MW

Shongtong-Karcham 402 MW

Thopan-Powari 480 MW

Jangi-Thopan 480 MW

Ghanvi II 10 MW

The proposed Tidong-I Hydroelectric Project has a capacity of 60 MW

and is located on the Tidong River , just upstream of Tidong-II HEP.

In addition to the Satluj, other rivers which are part of the Great Indus

Basin and pass through the State of Himachal Pradesh, also contribute to

the power potential of the State. The most important are: Beas River,

4586 MW; Ravi River, 2379 MW, Chenab River, 3832 MW.

Himachal Pradesh thus has considerable hydropower potential. In the

long run, it is more economical for development than thermal power, as it

utilises perennial natural resource which otherwise goes to waste. For the

prosperity of the state and benefit of the country the hydro-power

development in Himachal Pradesh needs a renewed thrust. The

hydroelectric potential of Himachal Pradesh, however, is not likely to be

consumed in the State, and therefore will be available for meeting the

requirements in other parts of the country, and particularly in the Northern

Region.

2.2.3 Thermal power potential of Himachal Pradesh

Himachal Pradesh being located in the far North end of the country and

considerably away from the coalfields, does not have any prospect of

7/30/2019 Tidong

19/162

TIDONG-IHEP

II - 6

having thermal projects. The same consideration applies to other northern

states.

2.2.4 Power Scenario in India

The installed capacity in India increased from 1362 MW in 1947 to 64,729

MW in 1990 at the end of the 7th Plan. During that period energy jumped

from 4 to 264 TWh. However, despite that appreciable growth, power

demand has almost throughout outstripped the supply.

At the end of the 7th Plan, the shortfall in energy availability on an " all

India " basis was 6.8%. The corresponding shortfall in peak availability

vis-a-vis demand was about 7.6%. In the Northern Region, the shortage

with regard to peak availability was 19%. In July 1991, the peaking

shortage for the country as a whole increased to 16.7% from 7.6% in

March 1990, while the energy shortage rose to 7.9% from 6.8%.

For the 8th Plan(1992-97), the Central Electricity Authority (CEA) had

estimated a need based capacity addition of 48000 MW, which was

scaled down to 30 558 MW taking into account the availability of

resources. At the end of 1997-98 India had an energy shortage of 8.1%

and a peaking shortage of 11.3%. Even with the planned capacity

addition of more than 30,000 MW, the shortages in the terminal year of

the 8th Plan, i.e. 1997, would continue to be at the same level. As a

matter of fact the situation is likely to be worse as slippages are

anticipated in the planned capacity addition.

2.2.5 Demand and Supply in Himachal Pradesh State

Himachal Pradesh, being mostly a hilly terrain State and located in the far

North end of the country, considerably away from the coal fields, has little

prospect of having thermal projects. Having considerable hydropower

7/30/2019 Tidong

20/162

TIDONG-IHEP

II - 7

potential, which is generally found to be more economical for

development than thermal power, power generation in the future for

Himachal Pradesh has to be essentially from hydro-power sources.

As per the 14th Electric Power Survey of India, carried out by the Central

Electricity Authority (CEA), the energy requirement of Himachal Pradesh

for 1990-91 was 1487 GWh. This demand was projected to increase to

2536 GWh in 1994-95. Similarly, the peak load requirement for 1990-91

was 325 MW, which was expected to increase to 541 MW in 1994-95.

Table 2.3 shows the supply of energy and power as well as future

demand during the period 1990-91 to 1994-95 as projected by Central

Electricity Authority (CEA) in the 14th Electric Power Survey of India.

Table 2.3POWER SUPPLY AND DEMAND FOR HIMACHAL PRADESH

Item 1990-91 1991-92 1992-93 1993-94 1994-95

Installed Capacity 274 274 296 301 301

Peak Availability 340 347 379 458 475

Peak Load 325 366 415 477 541

Surplus/Deficit 154.6

- 19- 5.2

- 36- 8.7

- 19- 4.0

- 66- 12.3

Energy Availability 2013 2047 2147 2521 2711

Energy Requirement 1487 1688 1925 2224 2536

Surplus/Deficit 52635.4

35921.3

22211.5

29713.4

1756.9

The future demand scenario for the period 1995-2010 as projected by the

CEA in the 15th Electric Survey Report with respect to Himachal Pradesh

is as depicted in Table 2.4.

Table 2.4Energy and Peak Load Demand for Himachal Pradesh

Period 1995 to 2010

7/30/2019 Tidong

21/162

TIDONG-I HEP

II - 8

Period EnergyDemand(GWh)

PeakDemand

(MW)

1995-96 2879 6091996-97 3254 683

1997-98 3662 763

1998-99 4103 848

1999-2000 4576 939

2004-05 7378 1457

2009-10 10606 2020

It can be observed that energy requirements are likely to increase duringthe period 1991-2010 from 1487 GWh in 1990-91 to 10606 GWh in 2009-

2010, and the peak load demand would do increase from 325 MW to

2020 MW during the same span.

2.2.6 Demand and Supply in the Northern Region

The hydropower potential of Himachal Pradesh, is obviously surplus to its

own requirement. However, it will be usefully made available to meet the

power and energy requirements in other parts of the country, and very

particularly, the Northern grid. This is the case of major projects such as

Bhakra and Beas, which supply power to the Northern grid. Another

example is the 540 MW Chamera Project, situated in the north-

western part of the State, which started operating in 1994 and supplies

New Delhi through a 510km long transmission line. For planning purposes

it is therefore necessary to study the energy and power requirements of

the Northern region as a whole, since the region will be the recipient of

any hydropower project likely to be developed in Himachal Pradesh in the

future. On the basis of the addition of capacity during the 8th Plan period,

7/30/2019 Tidong

22/162

TIDONG-I HEP

II - 9

the CEA has estimated the requirements of the Northern Region as

shown in Table 2.5.

Table 2.5

Power Demand and Supply for the Northern Region in the Period 1990-95

Item Unit 1990-91 1991-92 1992-93 1993-94 1994-95

Installed Capacity MW 19203 20581 22195 24274 26681

Peak Availability MW 11408 11291 12777 14008 15271

Peak Load MW 14908 16259 17721 19240 20814

Surplus/Deficit MW%

- 3500- 23.5

- 4338- 26.7

- 4944- 27.9

- 5232- 27.2

- 5543- 26.6

Energy Availability GWh 80803 82755 88165 95959 106143

Energy Requirement GWh 79338 86553 93396 102416 110841

Surplus/Deficit GWh%

14651.8

- 3798- 4.4

- 6231- 6.6

- 6457- 6.3

- 4698- 4.2

Table 2.6 lists the future energy and load requirements for the Northern Region.

Table 2.6

Energy and Peak Load Demand for the Northern Region

Period 1995-2010

Period Energy

(GWh)

Peak Load

(MW)

1995-96 119887 22466

1996-97 129587 24234

7/30/2019 Tidong

23/162

TIDONG-I HEP

II - 10

Period Energy

(GWh)

Peak Load

(MW)

1997-98 139976 26124

1998-99 151086 28143

1999-2000 162954 30295

2005-06 248332 45634

2009-10 318715 58117

From Tables 2.5 and 2.6, it can be seen that the peak demand over a

period of 20 years is likely to double from 14908 MW in 1990-91 to as

much as 58117 MW in 2009-2010.

2.2.7 Satluj river hydropower potential

The Government of India and the State of Himachal Pradesh have

identified the Satluj river as one of the main sources of hydroelectric

power, and have initiated several hydro-electric projects along the reach

of the river and its tributaries under their jurisdiction. These projects, in

varying stages of planning, construction, completion and operation,

include:

- Bhakra-Nangal, 1164 MW, under operation

- Kol, 800 MW, construction stage

- Rampur-Behna, 400 MW, concept stage

- Nathpa-Jhakri, 1500 MW, under operation

- Karcham-Wangtoo, 1000 MW, investigation stage

- Shongtong-Karcham, 402 MW, investigation stage

- Thopan-Powari, 480 MW, concept stage

- Jangi-Thopan, 480 MW, concept stage

- Pooh-Spillo 300 MW, concept stage

7/30/2019 Tidong

24/162

TIDONG-I HEP

II - 11

- Khab-Pooh 300 MW, concept stage

These projects are all run-of-the-river, with the exception of Bhakra-

Nangal. Additional hydro projects, planned and operating have been

identified on tributaries of the Satluj, such as Sanjay Vidyut Pariyojana -

Bhaba (120 MW, operating), Nogli (3 MW, operating), Ghanvi (22.5,

operating), Baspa II (300 MW, Operating) and Baspa I (concept stage).

Some of the potential projects listed here may not be built in near future,

but it is reasonable to assume that the preliminary studies have indicated

these projects to be technically feasible, there will be a strong motivation

to build them as the demand for power grows and limited fuel resources

tend to exhaust.

Further developments, in addition to those listed here, may be seriously

considered at some time on both the Satluj and its tributaries. A program

to develop small hydro projects on streams flowing through villages is

also in place.

2.3 NEED OF THE PROJECT

From the growth of peak demand and anticipated installed generating

capacity on the basis of schemes proposed for benefits under

construction/consideration during eighth and ninth five year plan, it is

observed that there is a dire need to provide additional capacity to the

Northern grid to meet the increasing demand of the grid. Thus new

scheme have to be taken up immediately and implemented to drive timely

benefits.

The most important source of power development in the Northern region

is Hydro resources located in Himachal Pradesh, Uttar Pradesh and

7/30/2019 Tidong

25/162

TIDONG-I HEP

II - 12

Jammu and Kashmir. Tidong-II Hydroelectric Project is very attractive

scheme from the view of deriving benefits in the beginning of Tenth Five-

Year Plan.

7/30/2019 Tidong

26/162

, TIDONG-I HEP

III - 1

CHAPTER 3

PROJECT AREA

3.1 INTRODUCTION

The Government of India and the State of Himachal Pradesh have

identified the Satluj river as one of the main promising future sources of

hydroelectric power. Development of Satluj waters was started in a big

way first by Bhakra-Nangal Project. Government have now initiated

several hydroelectric projects along the reach of the Satluj and its

tributaries. The Tidong-I Hydroelectric Project is envisaged as a run-of-

the-river development on the Tidong river, consisting of a diversion dam

across Tidong river downstream of confluence of Lalanti khad with

Tidong river near village Kairbu, a water conductor system and power

house near village Lamber in Kinnaur district of Himachal Pradesh.

3.2

LOCATION AND ACCESS

Himachal Pradesh is located in the western portion of the Great

Himalayan Mountain Range of northern India, bounded by the State of

Jammu-Kashmir to the North, Tibet to the East, and the plains of northern

India to the South and West. The Satluj river is one of the major rivers

draining this region. It rises in the Tibetan Plateau, passes via steep

valleys and gorges through the Himalayan Mountains and foothills and

meets the Arabian sea across the plains of Northern India.

The project site area is about 278 km from Shimla, the State capital, 250

km on National Highway 22 up to Morang and then 13 km on state road

up to village Thangi. From Thangi up to diversion site, about 16 km

7/30/2019 Tidong

27/162

, TIDONG-I HEP

III - 2

stretch road is under construction.

3.3 CLIMATE

The study region is upstream the dividing line between climatic zones I

and III of northern India. Zone I, the Tropical Monsoon climate, extends

from the Indian Ocean north as far as Wangtoo, with its effects modified

by elevation and topography. The tropical monsoon climate involves an

annual rainfall in excess of 1000 mm, occurring mostly in the months of

June to October. The study region, however, experiences little rainfall as

the mountains between the plains and the study region capture most of

the precipitation.

Climatic Zone III, the Arid Mountain Climate, affecting the Tibetan and

western China Plateau, is characteristically cold and dry in winter, and hot

and dry in summer. This is highly modified by the topography of the study

region. From November to May, the region experiences a generally north-

easterly flow of cold continental air moving out from across the Tibetan

Plateau. The effect of this flow is somewhat modified by the mountains

but it can result in high winds. Winter precipitation occurs as a result ofwesterly disturbances. From June to September, the region experiences

the south-westerly monsoon from the Indian Ocean, though, once again

the region's location in the heart of the Himalayas modifies the effect, and

precipitation is small.

3.4 GEOLOGY

The project area lies in Mehbar and Maldi gneisses comprised of kyaniteand psamatic gneisses with bands of schist and quartzite. These are

intruded by basic and acidic rocks. All the rocks are well foliated. The

general trend is N-S with moderate dips toward East. These are

transacted by a number of joints of which the foliation and strike joints are

7/30/2019 Tidong

28/162

, TIDONG-I HEP

III - 3

the most predominant followed in frequency by steeply dipping transverse

joints. The rock formations within the project area going upstream from

the tailrace consist of the Wangtoo, Rampur and Jutogh gneisses and

granites. The Wangtoo rocks are overlaid by the Rampur followed by the

Jutogh, the three series having thrusted contacts.

Rocks are generally covered by glacial deposits, rock debris, alluvial

terraces and fans. The soils of the Satluj valley are relatively poor sandy

loam, and exposed bedrock, rocks and gravel abound. In the valley

bottom there is virtually no soil, but between elevations 1200 and 3500 m,

the soils support some forest cover and are cultivable to a certain extent.

3.5 SEISMICITY

The project area lies in an active seismic region, zone IV of the Seismic

Zoning Map of India. Available data on seismicity within a radius of 150

kms of the project shows that earthquakes having a magnitude greater

than 5 on the Richter scale occur at frequent intervals. Important seismic

events which have taken place in the past 150 years and caused

significant damage include the 1905 Kangra quake (magnitude 8+), the1908 Kullu quake (magnitude 6.0), the 1945 and 1947 Chamba quakes

(magnitude 6.5 & 6.6), the 1975 Kinnaur quake (magnitude 6.8) and the

1991 Uttarkashi quake (magnitude 6.6).

3.6 SOCIO-ECONOMIC CHARACTERISTICS

The Kinnaur region has deep roots in Indian mythology, legends and

literature. The Kinnaur region was formerly a part of the princely state of

Bushahr. The State of Himachal Pradesh came into existence in 1960

and Kinnaur became a district. Contact with the outside world accelerated

when National Highway 22 was built by the Border Roads Organization,

following the 1962 Sino-Indian war. One immediate consequence of the

7/30/2019 Tidong

29/162

, TIDONG-I HEP

III - 4

road construction was that Kinnaur became integrated into the cash

economy of Himachal Pradesh. The State has continued to play a role in

introducing techniques and policies that have enhanced production

despite the poor soils of the area.

The people in the study area have developed a culture that is distinctive

for two reasons. First, they live in a socio-economic environment officially

designated as "depressed" and they were designated as "scheduled

castes" and "scheduled tribes". Prior to 1960, they were semi-nomadic

and sought opportunities to enhance their economic base and to forge

alliances with political and religious factions. Since the 1960s, the

economic base has expanded to encompass horticulture, which was

being promoted in the State. This has become a highly profitable growth

industry in the area. Kinnaur is the most important producer of apples in a

State famous for them. Secondly, the study area is home to two distinct

groups with common subsistence and trade practices. Over the centuries,

these groups retained their differences and developed shared values

which has resulted in "scheduled castes" and "scheduled tribes", Hindus

and Buddhists, with temples and monasteries existing side by side in the

villages.

7/30/2019 Tidong

30/162

TIDONG-I HEP

IV-1

CHAPTER 4

GEOLOGY

4.1 INTRODUCTION

The Central Electricity Authority (CEA) with the view to meet the

challenge of ever increasing demand for power in the country have

embarked upon an exercise to assess balance hydroelectric potential

in the country, formulate the probable hydroelectric schemes and rank

these schemes thus identified in the order of priority. A total of 162

schemes with probable installed capacity of 500,600 MW located in

various river basins of country have been selected for preparation of

PFRs in first phase. The schemes thus found feasible are proposed to

be taken up for further development in X and XI Five Year Plans.

Tidong-I is one such scheme identified in Tidong or Tirung valley in

Satluj basin in Kinnaur district in Himachal Pradesh. Tidong or Tirung

is a left bank tributary of the river Satluj in Morang Tehsil.

The proposed Tidong I Hydroelectric Project envisages construction of

a diversion dam across Tidong river downstream of confluence of

Chirong and Shurting Khads (31 28' N: 78 32'E; 53 I/11) near village

Kunnu, a water conductor system comprising a 5.036 km long HRT

and a power house (31 32'50" N: 78 30'15"E; 53 I/6,10) near village

Lamber with probable installed capacity of 60 MW.

4.2 REGIONAL GEOLOGY

The proposed project is located in the upper reaches of Satluj river in

the Kinnaur district of Himachal Pradesh. The area around the project

7/30/2019 Tidong

31/162

TIDONG-I HEP

IV-2

presents a highly rugged topography. The torrential drainage

developed in the area with the Satluj as main artery has formed deep

gorges. The lowest and highest altitudes in the district at 1220 m and

6770 m above MSL are index of high ruggedness. In general the

northwestern sides the mountains in the NE-SW trending valleys are

precipitous while both sides in NW-SE treading valleys are equally

steep.

The Satluj, trunk river in the area is the longest river and flows from

NE-SW. The left bank of the river has patches of large plain lands. The

other important streams of the area are Spiti, Baspa, Bhaba, Ropa &

Tidong. These form an over all trellis pattern whereas individual rivers

have dentritic pattern indicating structural control on the drainage.

Hanging valleys, fossil valleys and abandoned and buried channels are

quite common. The altitude above 5200 m is perpetually snow bound

and that above 4250 remains under snow for at least six months.

There are many glaciers in the area. These are mainly in longitudinal

as well as valley type. Occasionally hanging glaciers are observed in

Baspa, Tidong and Taiti valleys. Lateral median moraines are always

associated with these glaciers. The glaciers show overall shrinkage.

The valley profiles across Satluj and a few other major tributaries show

that the valleys have been depended by about 500 m by fluvial

processes since last glaciation. This zone is marked by both erosional

and depositional terraces.

In the regional overview, the Kinnaur district occupies a position as

harbinger between the Kumaon and Punjab Himalaya with Satluj river

forming the divide (Bassi, 1988). The rock types vary from highly

7/30/2019 Tidong

32/162

TIDONG-I HEP

IV-3

metamorphosed schists and gneisses to shale and sandstone ranging

in age from Middle Pre-Cambrain to Cretaceous. The rocks exposed in

Upper Satluj Valley where the project is located belong to Vaikrita and

Haimata Groups ranging in age from Middle - Late Proterozoic to

Lower-Middle Cambrian. The geological succession worked out by

Bassi (1988) based on the work of several workers is as follows:-

GROUP FORMATION LITHOLOGY AGE

______Rakcham Granite_____

Kunzum La Greenish Slates 4 Quartzite Lower-MiddleCambrian.

Haimanta

Batal Grey Phyllite, quartzite, Lower Venedian to

(Hilap) Carbonaceous Slates Lower Cambrian

Shiasu Greenish & purple quartzite

Schist bands.Vaikrita

Morang Biotite sillimanite bearing Middle-Lower

(Maldi) Schist, quartzites Proterozoic

Kharo Sillimanite-Kayanite bearing

gneiss, calc-silicate rock

sporadic migmatite.

The felspathic gneiss, quartzite, high grade, schists and migmatite of

this group exposed in an arcuate pattern, rest over the Jutogh,the

Salkhala and Rampur Groups alongwith Vaikrita Thrust. These rocks

are intruded by Rakcham and Nako Granites. The rocks of Vaikrita

Group extend towards northeast along the Satluj and Spiti valleys upto

7/30/2019 Tidong

33/162

TIDONG-I HEP

IV-4

Shipki La and Sumdo. The rocks belonging to Vaikrita Group have

been divided into three formations viz Kharo, Morang, Shiasu.

The Kharo Formation includes the lower part of Granulite Series of

Jhingran et al (1950), the Mehbar, Mongling and Porphysoblastic

gneisses of Gaur and Ameta (1978-79,80) and Ameta and Swain

(1980-87) and units 4 & 5 of the Jutogh formation of Kumar &Nagal

(1983). It is restricted to west of Rakcham Granite and is well exposed

along Kupa-Rakcham, Shongtong-Kharo-Khadra and Pawari-Kalpa

road sections. The gneissic rocks of Kharo Formation are argillo -

arenaceous towards base, felspathic towards middle and migimatised

towards upper parts along the contact with Rakcham Granite. The

basal part exposed near Shongtong is mainly schistose with profuse

development of kyanite. The schistose rocks are interbanded with dark

grey quartzite. Towards upper part i.e. in Thopan-Kharo-Khadra

sections, the gneisses develop migmatitic characters with the increase

in granitic material. Ptygmatic folding and dilation structures leading to

boudins are frequent. Small bands of schist and quartzite are

ubiquitous in these gneisses. According to Bassi (1988), the basal

Kharo Formation may infact represent the feldpathised and migmatised

deeper parts of Morang Formation.

The Morang is exposed along the Satluj valley between Akpa and

upstream of Spillo and Dabling.It occupies a large part of Spillo gorge

and its flank right up to the Tibetan water divide. In this sector it is

intruded by a leucogranite (Nako Granite) and is named alter Morang

village where it is best developed. It has earlier been mapped as

Haimanta (Hayden, 1904). Granulite Series ( Jhingran, et.al, 1950),

Jangi Formation (Kathiara and Venugopal, 1965) and Maldi Formation

(Bassi and Chopra, 1983 & Kumar and Nagal 1984). It is separated

7/30/2019 Tidong

34/162

TIDONG-I HEP

IV-5

from the underlying Kharo Formation by the Rakcham Granite

emplaced along the contact. This formation consists of schists and

quartzite with rare thin calc silicate and marble bands. The schist

shows a variable metamorphic mineral assemblage i.e. biotite garnet

staurolite kyanite sillimanite. Biotite is the most predominant

lithology. The biotite schist grades into garnet-mica schist which is

exposed in the Morang. Thangi, Jhangi-Khanam, Morang-Spilo, Titan,

Kha-La Namgiya-Shipki-Toshigang and Malig-Chango sections. The

staurolite schist passes in to Kyanite schist which is very well

developed at Morang Jhoola, Jangi, Dabling-Khab. Sillimanite has very

restricted development. It is observed in the road cuttings 500 m south

of Khab as radiating clusters in crudely foliated and greyish coloured

schist. The schists are interbanded with dark grey quartzite, which

originally may have been sub arkoses. The marble lenses containing

tremolite, actinolite and epidote etc. are observed in Naleo Nala,

Morang Nala sections, Khab Dogri and east of Maling.

Shiasu Formation is exposed in the Satluj gorge between 2 km

upstream of Spilo to 2 km downstream of Khab. These are well

exposed in Ropa valley between Shiasu and Ropa. This formation

conformably overlies the Morang Formation. Shiasu Formation

consists of grey green and purple shaded, fine grained fairly

recrystallized quartzite with minor biotite and chlorite schist. The

quartzite often shows cross bedding, ripple marks and rare current

bedding.

The rocks of Vaikrita Group are succeeded by those belonging to

Haimanta Group. This group includes the basal Eocambrain Batal and

the Cambrain Kunzam La Formations. It is characterized by low grade

metamorphic phyllite, slate and quartzite. These are dark, pyritous and

7/30/2019 Tidong

35/162

TIDONG-I HEP

IV-6

carbonaceous in basal part and light grey to greenish coloured in the

upper part. The rocks belonging to Batal Formation are widely exposed

in both Spiti and Kinnaur basins, its extrusion is cut off by a fault near

Leo. In the Kinnaur Basin it forms the lower part of the Hilap Formation

(Bassi & Chopra, 1978) and maintains a constant thickness right up to

Shipki in north to the Jadhganga valley in the southern part. It

unconformable overlies the Vaikrita rocks, overlapping the Shiasu

Formation and shows distinct structural and metamorphic discontinuity

from the underlying high grade Vaikrita rocks.

Batal Formation comprises an interbedded sequence of dark grey

phyllite and sub arkoses with carbonaceous horizons towards the

basal part. A carbonaceous bed defines the base of this formation.

Overall, it is more argillaceous towards the base and top, whereas

middle part is more arenaceous. The sedimentary structures are

virtually absent except for rare small scale cross bedding over

quartzite. Pyrite is extensively developed in all the litho units. This

formation in the upper part contains 2 m x 10 m lenticular gritty and

conglomeratic bands. Volcanic elements in the Batal Formation are

represented by a thin band of actinolite schist with deformed vesicle

like cavities filled with chert and/or granular pyrite exposed 250 m

west of Murmur Dogri in Hogis Valley. The Kunzam La formation

gradationally overlies the Batal formation and is exposed in the

Kinnaur basin with uniform thickness right from Yangti Valley in the

north to Jadhganga valley in southeast. In Spiti Basin it shows gradual

reduction in thickness upto south Hangrang pass where its northern

extension is cut off by Kaurik Sangnam Fault. It is characterized

predominantly by greenish slate, subarkose, siltstone, grit and minor

dolomitic lenses in the upper part. It contains restricted volcanogenic

7/30/2019 Tidong

36/162

TIDONG-I HEP

IV-7

elements in the Hojis, Tidong and Chorgad valleys. East of Ropa

valley, slate and siltstone are dominant.

The Kunzan La Formation of the Kinnaur Basin enclosed some

volcanogenic elements, which includes a number of tuffaceous

lenses,. It also contains a few grit bands and local intraformational

conglomerate.

Rakcham Granite is exposed in a long arcuate belt in southwestern

part of Kinnaur. It is medium grained often prophyritic granite with

biotite as constant mafic mineral. It becomes aplitic places. Broadly,

the granite shows zoning defined by finder grained margin, slightly

wider prophyritic zone followed by medium grained nonfoliated core. It

shows both concordant and discordant contacts along the eastern

margin and, migimatised contact along the western. The later phases

associated with the granite are aplite and pegmatite and veinquartz.

The pegmatite venis are more frequent in the area where schist of

Morang Formation is in contact with granite. Nako Granite is exposed

mainly in Tashigang-Nako-Leo Pargial area. Smaller bodies of it are

observed right from Khab-Shipki to Pare Chu gorge in the north. The

Nako Granite outcrops are restricted to the area east of Kaurik-

Sangnam Fault. It is leucocratic, massive, nonfoliated and both biotite

and tourmaline bearing. It is intrusive into the Middle Proterozoic

Morang and Carboniferous Lipak Formations. Numerous pegmatite

and aplite veins of varying dimensions are observed in Khab-Chango-

Leo area.

7/30/2019 Tidong

37/162

TIDONG-I HEP

IV-8

4.3 STRUCTURE & TECTONICS

Both primary and the secondary structures are abundant in the rocks

of this area latter being more varied and complex in the Proterozoic

rocks. Major primary structural elements in the area include bedding

which is easily discernible in the Tethyan Batal-Guimal sequence

because of unmetamorphosed character and lithological banding.

Quartzite helps in defining bedding metamorphosed Vaikrita rocks.

Sedimentary structures present in Vaikrita include cross bedding,

ripple marks, exposed slumps etc. These do not indicate large scale

overturning of beds.

Both planar and linear secondary structures recorded in the area

include schistosity , joints, lineations, puckers etc.

At least three major episodes of folding have affected the rocks of this

area. The intensity of folding is drastically reduced in the rocks of Batal

and younger formations. The F1 folds are low plunging gently inclined,

sub-horizontal to recumbent/reclined often intra folial. These are

restricted to Vaikrita Group of rocks. These in general show a

southeasterly plunge. F2 folds are usually low to moderately plunging

gently inclined asymmetrical to semi recumbent and often reclined.

More often these are co-axial with the F1 folds. Small scale

superimposed 'Hook' or 'Diamond' folds in some area. The plunge of

F2 folds is in general towards NW in the area west of Satluj and

towards SE in the area lying to its east. These are most prevalent fold

types and constitute regional folds like Tiya Syncline, Ropa valley

Anticline, Gangchua, Anticline, Nakdum Anticline, Tiwei Syncline etc.

The F3 folds are represented by NE plunging antiforms and those on

smaller scale in upper reaches of Ropa Valley and along Baspa-

7/30/2019 Tidong

38/162

TIDONG-I HEP

IV-9

Tidong water divide. These are represented by Lower Satluj Anticline,

Shias-Shipki Anticline Wangtu Dome etc .

Apart form three major thrusts i.e. Salkhala Thrust, Jutogh Thrust and

Vaikrita Thrust, located near Karcham, the major faults recorded in the

area Raura Gad Fault, Sumdo-Na Fault, Chorgad Fault Kaurik-

Sangam Fault. The last one located in the vicinity of project area is a

steep fault running NNE-SSW and dipping 50-55 towards west.

Southward, it dies out in Rakcham Granite but towards N it extends

into Tibet. In Spiti Valley, it is associated with numerous sub parallel

and anatomizing faults. Broadly it demarcates the western and

eastern limits of the Nako Granite and the Tehyan rocks. In addition, a

number of shears and smaller faults have been recorded in the area.

These generally trend NNE-SSW and are sub parallel to

foliation/bedding.

4.4 SEISMICITY & SEISMOTECTONICS

Seismotectonically, the area encompassing the proposed Project is

located in Main Himalayan Belt and on the western margin of Garhwal

Seismic Block of Narula (1991). It is bound by Kaurik Fault (KF) in the

west. Within MHB, the tectonic packages are Tethyan and Lesser

Himalayan cover sequences affected by Himalayan Orogeny, low and

high grade complexes tectonically reworked during Himalayan

Orogeny and respectively pre and syntectonic granitoids and basic

volcanics(Narula et al.2000). The Foothill Belt constitutes foredeep

sediments affected by terminal phase of Himalayan Orogeny. The

northern - most tectonics elements is the dextral Karakoram Fault

which is sub parallel to Indus Suture Zone (ISZ) occurring to its south.

Within Himalayan Belt, northernmost conspicuous structural elements

7/30/2019 Tidong

39/162

TIDONG-I HEP

IV-10

is Main Central Thrust (MCT). Further south, within Lesser Himalayas,,

the other important structural element are Vaikrita Thrust (VT). The

Main Himalayan Belt is separated from Terrary Frontal Fold Belt by the

Main Boundary Thrust(MBT) and the southern limit of Frontal Fold Belt

is marked by Main Frontal Thrust (MFT), which has surface

manifestations at many places. Neotectonic activities have been

recorded along the Karakoram Fault, ISZ, MCT, MBT and MFT at

many places. A number of transverse N-S and NNE-SSW faults of

limited extent have been mapped in the area. Kaurik Fault is one such

fault which is considered to have triggered the Kinnaur Earthquake of

19" January, 1975. Similarly Raura Fault, Yamuna Tear, Ganga Tear

and Mahendragarh-Dehradun Fault, a subsurface structure in fore

deep are some such planes.

Seismically, the area constitutes a part of most active domains of the

Himalayas although the area west of it lying in Shimla Seismic Block

is slightly less active. The area around the project between longitudes

76 & 80 has recorded about 34 earthquakes between 1816 and 1997

having magnitude more than 5.0. Area-wise, seismicity is quite high in

MHB, subdued within Tibetan Plateau and a few events located over

Indo-Gangetic Plains. Within Himalayan Belt, the clustering of seismic

events defines, two distinct zones having varied trends. The Kinnaur

Seismic Zone in which the proposed project would be located has N-S

alignment and is traversed by a number of half graven faults defining

the Kaurik Fault system. The other zone located further southeast is

roughly parallel to Himalayan trend and extends from Uttarkashi to

Dharchula and lies in close proximity to MCT. Both these zones are

dominated by shallow focus events though some deeper events, have

also been recorded in Kaurik Fault Zone. Several damaging

earthquakes have been recorded in the area of which Kinnaur

7/30/2019 Tidong

40/162

TIDONG-I HEP

IV-11

Earthquake on 19th January, 1975 (Mb=6.2), Uttarkashi Earthquake of

19th October, 1991 (Mb=6.4) caused extensive damage in the area. As

per Map of India showing Seismic Zones of India (IS 1893 -Part. 1 :

2002), the area is located on the margins of zones V & IV. Therefore it

is recommended that suitable seismic coefficient as per seismic status

of the area may be incorporated in the design of various appurtenant

structures of the schemes.

4.5 GEOTECHNICAL APPRAISAL

The proposed Tidong I Hydroelectric Project envisages the

construction of a 65 m high storage dam across the river Tidong

downstream of confluence of Chirong Khad with Tidong, a water

conductor system comprising 5036 m long Head Race Tunnel (HRT)

and power house with probable installed capacity of 60MW on the left

bank of Tidong upstream of its confluence with Lamber khad. The

reservoir thus formed is likely to have storage capacity of 88 mcum.

The geological map of the area indicates that the rocks exposed in the

area include phyllite, quartzite and carbonaceous slate belonging to

Batal Formation of Haimanta Group. These are intruded by Rakcham

Granite that is extensively exposed in the area at lower elevations in

the valley of Tidong and its tributaries. The strike of sedimentaries in

the area varies between NNW-SSE and NE-SW due to folding. The

site of storage dam shows Rakcham Granite exposed at lower

elevations and sedimentary rocks belonging to Batal Formation at

higher elevations. It is suggested that final site for 165m high dam be

selected after assessing the extent of overburden in the river bed and

on abutments, topography of the site and availability of suitable

locations for HRT intake and diversion structure. The Rakcham Granite

is expected to provide good foundation media. However, distressing

7/30/2019 Tidong

41/162

TIDONG-I HEP

IV-12

limit, if present on the abutments be assessed and structure designed

accordingly. The 5.036 km long HRT proposed to be aligned on the

right bank of Tidong. It is expected to encounter Rakcham Granite,

which is jointed. Rakcham Granite is expected to be good to very good

tunneling media except for the reaches where local fault/shear or

closely jointed zones are encountered.

The geological map indicates that HRT would cross several surface

drainages. It is suggested that adequate rock cover be ensured over

the structure. It is also suggested that too high rock cover in this highly

tectonised zone also be avoided in order to minimize the mobilization

of locked up stresses. Keeping in view the length of HRT, it is

suggested that HRT be aligned in such a way that atleast one

intermediate construction adit is available for facilitate construction.

The powerhouse with probable installed capacity of 60 MW is

envisaged downstream of confluence of Tidong and lamber khad.

Keeping in view the hostile climate, constraint of space available and

rugged topography, it is suggested that structure may be designed as

an underground structure for which Rakcham Granite may provide very

good to good excavation media. However, location of ancillary

structures be kept in view while finalizing the site for power house. The

project is located in Zone IV and is in close proximity to Zone V in

Higher Himalayas as per Map of India showing Seismic Zones (IS-

1893: part I, 2002). Therefore, necessary seismic coefficient be

incorporated in the design of appurtenant structures of the project. This

preliminary geotechnical appraisal is based on regional geological set

up .

7/30/2019 Tidong

42/162

TIDONG-I HEP

IV-13

REFERENCES:-

1 Bassi U.K., (1988). Final Report on the Geology of the Kinnaur district,

Himachal Pradesh(Compilation), Unpubl. GSU Report.

2. Bassi U.K., and Chopra, S. (1980). Geology of a part of Kinnaur

district, ,(Lower Tidong Valley), Himachal Pradesh Unpubl. GSI Report

for F.S. 1978-79.

3. Narula, P.L., Accharya, S.K., and Banarjee J., (Eds.)(2000).

Seismotectonic Alas of India and its Environs, Publ. Geological

Survey of India.

4. Narula P.L.(11991). Seismotectonic Evaluation of NW Himalayas, Rec.

Geol. Surv. Ind., Vol.124 (8), pp 193-194.

7/30/2019 Tidong

43/162

TIDONG-I HEP

V-1

CHAPTER 5

HYDROLOGY

5.1 INTRODUCTON

Tidong Khad has its origin in the North Western slopes of Great

Himalayas ranges at an altitude of 6740 meters. It mostly flows in

South-Easterly to North- Westerly direction. A number of Nallas join

Tidong Khad upto its origin to its confluence with Satluj River near

Morang in District Kinnaur of Himachal Pradesh.

5.2 PROPOSAL

Tidong Stage I Hydroelectric Project (60 MW) is being envisaged as

a run off the river scheme in District Kinnaur of Himachal Pradesh.

The Project consists of construction of a concrete gravity Dam across

Tidong Khad just downstream of the confluence with Lalanti Khad

(near Kairbu village), an underground desilting arrangement on the left

bank of the river, a 5.036 km long head race tunnel and a 3.5 m dia

surge shaft (u/g) and inclined pressure shaft and an under ground

power house on the left bank of Tidong Khad near village Lamber. The

power house shall house two units of 30MW each to produce 60 MW

of power.

.

5.3 CATCHMENT CHARACTERSTICS

Catchment of Tidong Khad lies between Latitude 31 2030 N to 31

3330 N and Longitude 78 2210 E to 78 4750 E. The altitude of

Tidong Khad ranges from 2200 meters at its confluence with Satluj

river to 6740 meters in the glacier zone. Survey of India toposheet

7/30/2019 Tidong

44/162

TIDONG-I HEP

V-2

numbers 53 -I/6,53-I/7,53-I/10,53-I/11 and 53-I/15 in the scale 1:50000

cover the catchment area of the project.

The catchment area above diversion dam site comprises of steep

mountains, a portion of it is covered with forest and major part is under

permanent snow. Total catchment area up to weir site is 497.86 square

kilometers . Catchment area above permanent snow line i.e. El 4200

meters is 472 Sq. kilometers respectively. The catchment area has

been shown in Figure-1. The average slope of khad just upstream of

diversion site is 1:50, and thereafter it has a steep descent (slope

1:10), making it most lucrative scheme for hydroelectric potential

exploitation.

The permanent snow line for the project has been taken at 4200 m.

5.4 HYDROMETEOROLOGICAL ASPECTS

The catchment in Tibet receives practically no rainfall and precipitation

is mostly in the form of snow. No meteorological data for this

catchment is available for the present study. . Observations at six

precipitation station i.e. Purbani, Kalpa, Sangla, kilba, Nichar and

Rampur are being carried out in the catchment of Satluj river. These

observations, rainfall since long and snowfall introduced only recently,

are being conducted in a conventional manner. There is no self

recording rain gauge/snow gauge station in the catchment up to weir

site. There are in all twenty rain gauge stations in the Satluj catchment

up to Bhakra Dam site.

5.4.1 Precipitation

Precipitation in the Tidong Khad catchment area occurs mostly in the

form of snow, which can be described as moderate to heavy

depending upon the altitude.

7/30/2019 Tidong

45/162

TIDONG-I HEP

V-3

Average annual precipitation is of the order of 630 to 700 mm, most of

which is received in the form of snow during winter months.

`

5.4.2 Record of Precipitation

There are at present five rain gauge stations in the catchments around

the Project site at which long term records are available and whose

records are being regularly published by the Indian Meteorological

Department. The relevant details of these stations are given in the

following table:

TABLE

DETAILS OF RAINGAUGE STATIONS

_________________________________________________________

Name of Station District Altitude Year of commencement

(In mtrs,)

_________________________________________________________

Purbani Kinnaur 2285 1951

Kalpa -do- 2530 1951

Sangla -do- 2590 1951

Kilba -do- 2200 1882

Nichar -do- 1830 1930

_______________________________________________________

There is no regular and systematic record of snowfall at any station in

the catchment although snow observations have been recently started

at some stations i.e. Purbani, Kalpa, Sangla, Kilba and Nichar from1984.

7/30/2019 Tidong

46/162

TIDONG-I HEP

V-4

5.4.3 Stream Flow Gauging

Discharge measurement of Tidong site has been started from June

1995 and data is available with effect from June, 1995 to Dec, 1998

only and from Jan 2003 onwards. Hence the discharge data for the

power studies has to be co-related from that available in the similar

catchments nearby. The similar catchments where the discharge

measurements for a long period .are available and the relative

information is given in table below.

Table

Khad/River

Catchmentarea

Highestelevationin thecatchment

Gaugesiteelevation

Period

Bhaba280 Sq Km 5619 2400 1980-97

Kangti Nallah 60 Sq Km 5351 2800 1980-97

Baspa river(atRakchham)

725.8 Sq Km 5800 3080 1980-94

Baspa riverat Sangla)Satlujriver(at Khab)

967.72 Sq.Km.

37000 Sq.Km

5800

7000

2400 1980-93

1985-98

5.5 FLOW SERIES

5.5.1 10- Daily Flow Series At Tidong I Dam Site

Ten daily flow series at dam site has been developed on proportionatecatchment area basis from approved discharge series of Tidong II

HEP, which had been attempted from the available ten daily

concurrent discharge data (1995 onwards)of Baspa river and Tidong

khad at Lamber.

7/30/2019 Tidong

47/162

TIDONG-I HEP

V-5

The ten daily approved discharge series (CWC) for Tidong II HEP is

appended at Annex 5.3 and the ten daily converted discharge series

for Tidong I is shown in Annex 5.2.

5.6 DESIGN FLOOD

Design flood studies shall be studied and submitted at the time of

preparation of Detailed Project Report.

5.7 RECOMMENDATIONS

i) Long-term rainfall/ snowfall data available in the catchment may

be collected and the discharge data may be cross-checked.

ii) Discharge data to be collected.

7/30/2019 Tidong

48/162

TIDONG-I HEP

VI - 1

CHAPTER 6

CONCEPUAL LAYOUT PLANNING

6.1 GENERAL: -

Tidong-I Hydroelectric Project located in Kinnaur district of Himachal

Pradesh, is a storage type development proposed to harness the

hydel potential of river Tidong between Charang and Lamber villages.

The project envisages construction of a concrete gravity dam across

Tidong river near village Kairbu for diversion of a design discharge of

13.45 cumecs, through a desilting tank into a 5.036 km long, 2.60 m

(finished) diameter head race tunnel on the left bank of Tidong river.

The tunnel terminates in a 3.50m-diameter underground surge shaft.

The water from surge shaft shall be further conveyed through

surface/underground penstock 825 m long, bifurcated near the power

house in to two branches each branch feeding one unit each of 30 MW

generating units in an underground power house at Lamber. A gross

head of 550 m is available at the power station, which shall be utilized

to generate 60 MW (2x30MW) of power.

6.2 MAIN COMPONENTS OF THE PROJECT

6.2.1 Diversion Dam

It is proposed to construct a 65 m high(from river bed) concrete gravity

dam across Tidong river just downstream of confluence of Lalanti khad

with Tidong river at an elevation of 3370.00 m to divert a design

discharge of 13.45 cumecs.

7/30/2019 Tidong

49/162

TIDONG-I HEP

VI - 2

Details of diversion dam are indicated in drg no HPSEB/TD/DPR-05.

6.2.2 Desilting arrangement

A conventional type surface desilting arrangement has been proposed

to exclude the sand particles larger than 0.2 mm The arrangement

comprises two parallel compartments each consisting of two chambers

64 m long, 12.00 m high (including 3.5 m hopper portion) and 7.10 m

wide. Each chamber shall have a 1.00 m diameter collection pipe in

the center and the hopper portion of the chamber slopes towards this

trench. The sediments from the collection trench will flow down to the

flushing pipe, and ultimately flushed out to the river.

Control valves will be provided at the junction of these silt flushing

pipes.

The layout and other details of desilting arrangement are shown in

drawing. NO HPSEB/TD/DPR/NO-06.

6.2.3 Head race tunnel

The head race tunnel, from the junction point at outlet from desilting

chambers to the main surge shaft, is 5.036 km. long and 2.60 m

(finished) diameter circular in section. The tunnel diameter is based on

techno-economic studies for a discharge of 13.45 cumecs at a flow

velocity of 2.53 m/sec. The rock cover on the head race tunnel, laid to

a slope of 1 in 129 will vary from about 90 m to about 900 m along its

length. The head race tunnel shall be concrete lined with sections fully

supported/partially supported with steel ribs, besides necessary rock

bolting as required by geological considerations.

7/30/2019 Tidong

50/162

TIDONG-I HEP

VI - 3

6.2.4 Surge shaft

The main surge shaft, located at the intake of the penstock at 5.036 kmfrom the 0 RD of head race tunnel, will be 3.50 m dia and 108 m high

with a restricted orifice. A 2.50 m D-shaped adit is proposed at El

3250.00 m to approach the bottom of the surge tank to facilitate

construction. The top of the shaft shall be approached for construction

through a 3.50 m D-shaped adit.

6.2.5 Penstock

One no surface penstock 2.10 m dia would take off from the surge

shaft at an elevation of 3250.00 m. the length of surface penstock is

825 m, thereafter it is a 100 m deep pressure shaft, which shall be

bifurcated near the under ground power house in to two 1.8 diameter

branches. These would be lined with high tensile steel corresponding

to ASTM-A-537 varying in thickness from 12mm near the penstock

intake to 35mm at the power house end. A spherical valve has been

provided in branch to enable closing of penstock whenever required.

The lower portion of the penstocks shall be executed through an adit

taking off from the tail race.

6.2.6 Power house

An underground power house cavern of internal dimensions 89.5 m x

15.5 m and 32.15 m high would be located about 130m below the

natural surface level. The power house cavern will have an arched roof

with concrete lining and shall house two generating units, each of 30

MW capacity. The transformer hall and underground switch yard are

7/30/2019 Tidong

51/162

TIDONG-I HEP

VI - 4

also located upstream of the power house cavern. Rock bolting at

suitable spacing will bee provided in these caverns.

Two (overhead) cranes each of 75 T capacity with crane girders

supported on rock at either and will be provided in the main power

house cavity. The capacities of cranes proposed to be installed in the

valve house, transformer and switch yard will be 75 and 10 T

respectively.

The generator floor and the service bay floor would be at the same

level. Provision has also been made for auxiliary rooms and other

service facilities at one end of the power house.

Two utility tunnels taking off from the tailrace tunnel shall be provided

to approach the bottom portion of the power house cavern and shall

facilities the excavation of the cavern and pressure shaft from the

bottom. To approach the top of the machine hall as also the top of

cavern, an adit is proposed to be constructed with its portal at EL.

2860.00 m. This adit shall be used for construction of arch portion and

other works from the top and shall be used as cable cum ventilation

tunnel.

6.2.7 Tailrace tunnel

The tail race tunnel with 2.60 m circular section, 100 m long will be

provided to carry the discharge back in to the Satluj river. The invert

level of this tunnel at its portal end has been kept at EL 2881.00 m.

The excavated section will be supported with steel ribs 200 mm

7/30/2019 Tidong

52/162

TIDONG-I HEP

VI - 5

spaced at 1 m c/c and 20 cm thick initial concrete, as the excavation

proceeds.

6.3 RECOMMENDATIONS

Project components are based on the conceptual layout only which

may be firmed up by detailed survey and detailed geological

investigations to be carried out as per CWC/CEA guidelines.

7/30/2019 Tidong

53/162

TIDONG-I HEP

VII - 1

CHAPTER 7

POWER AND ENERGY BENEFITS

7.1 GENERAL

Tidong-I Hydel Project has been conceived as run of the river

development for generation of hydropower. The project consists of

construction of a diversion dam across Tidong khad, a tributary of

Satluj river, just downstream of confluence with Lalanti khad near

Kairbu village in District Kinnaur of Himachal Pradesh. The water so

diverted shall pass through a desilting chamber, head race tunnel and

penstock to an underground power house near village Lamber on the

left bank of Tidong river to generate 60 MW of power. The power

house shall house two units of 30 MW each driven by Pelton turbine.

7.2 POWER POTENTIAL

7.2.1 Water Availability

Ten daily derived water series at diversion site for a period of 38

years from 1965-66 to 2002-03 has been shown in Annex 7.1.1.

Water series for Tidong I has been approved by Hydrology (N)

Directorate vide letter no 149 dated 7.5.04.

7.2.2 90% and 50% dependable year flow series

Energy generation in a hydrological year (June to May) have been

computed and is shown in Annex 7.1.1.For computation of 90% and

50% dependable year discharges, the unrestricted annual energy

generation series has been developed as shown in Annex 7.1(2). The

7/30/2019 Tidong

54/162

TIDONG-I HEP

VII - 2

unrestricted energy generation in a hydrological year (June-May) has

been arranged in descending order of magnitude and exceedence

frequency computed by using Weibull's plotting position farmula p=

(m/m+1) as given in Annexe 7.2. From the Annexe 7.2, it is observed

that year 1970-71 with an excedence probability of 89.47 % can be

used as 90 % dependable year on a safer side. Similarly 1973-74 with

a frequency of 50 % has been taken as 50 % dependable year. Flows

in a 90 % dependable year and 50 % dependable year has been given

in Annex 7.3. Generation in a 90% and 50% dependable year works

out as 211.65 and 242.99 MU and has been given in Annex 7.4 & 7.5

respectively.

7.3 FLOW DURATION CURVE

Flow duration curve at diversion site has been established from the

ten daily discharge data at diversion dam site, which has been derived

from ten daily discharge data available at Baspa at sangla as

explained in chapter 5.4.1. The flow duration curve has been shown in

figure 7.1. From this curve the discharge prevalent and exceeding

90% of time has been computed as 2.27 Cumecs while discharge

prevalent and exceeding 50 % of time has been computed as 3.97

Cumecs. The design discharge of 13.45 cumecs is available for 20.92

% of time.

7.3.1 Design Head

Gross head between MDDL and C/L of unit level is 550 m. The designhead adopted for the turbines has been taken as 511.7 mtrs.

considering fluctuations.

The basic parameters are as below: -

FRL = EL 3435 m

7/30/2019 Tidong

55/162

TIDONG-I HEP

VII - 3

MDDL = EL 3390 m

C/L of unit = EL 2885 m

Gross head = 550.00m

Highest flood level = 2875.00m

Losses in water conductor system = 20.00 m

at 13.45 cumecs discharge

Net head = 511.70 m

Design head = 511.70 m

The design head of 511.70 m is well within the range permitted for

Pelton type turbine from cost and efficiency considerations.

7.4 FULL RESERVOIR LEVEL(FRL) AND DAM HEIGHT

Area capacity curve for straight gravity dam has been shown in figure

7.1. Full reservoir level of 3435m has been kept in view of the fact that

Kunnu village in the periphery of the reservoir and cultivable area does

not gets submerged.

DAM HEIGHT

The river bed level at the proposed dam site is 3370.00m. The river at

this location has a straight reach with well defined banks. On both the

banks good quality rock is exposed and on the river bed rock is

expexted to be available at the reasonable depth.

Thus a dam of 68m height (above river bed) is proposed for diversionof Tidong Khad water for power generation.

7/30/2019 Tidong

56/162

TIDONG-I HEP

VII - 4

7.5 MINIMUM DRAW DOWN LEVEL

The river bed level at the dam site is 3370.00m. The sluices in the

dam body have been kept at El3377.00m for flushing out the bed load

deposited upstream of the dam during high flood season. Since the

project is a run of the river scheme, no separate provision has been

made for dead storage. The sill level of sluices has been kept 7.00m

above the river bed so that flip buckets are kept clear of tail water. To

avoid the bed load from entering into the intake, the intake sill level is

kept at 3383.00m i.e.4.5 m above the sill level of sluices. To avoid

vortex formations front of the intake, the minimum draw down level

(MDDL) has been fixed as 3390.00m.

7.6 INSTALLED CAPACITY STUDIES

Detailed studies for fixing installed capacity of Tidong I HEP has been

carried out and the same is elucidated in the succeeding paragraph.

Incremental energy studies have been carried out for different installed

capacities from 50MW to 140MW at an interval of 5MW for 90%

dependable year and are shown in Annexe 7.6. A graph has been

plotted as installed capacity vs incremental energy. Also installed

capacity vs total energy generation has been plotted as shown in chart

7.7. Incremental energy benefit is significant up to 60MW, then

constant in range 80MW- 100MW . The capacity fixed for the project is

60MW.

7.7 UNIT SIZE

The unit size has been selected after due consideration of the following

factors:

7/30/2019 Tidong

57/162

TIDONG-I HEP

VII - 5

a) The installed capacity should be delivered by units of same capacity to

minimise costs and reduce the spare parts and special tools required

for operation and maintenance.

b) The units should be as large as possible to obtain the benefits of scale.

c) The penstocks, turbines and generators should not be so large that

their components cannot be transported and assembled at site.

After due consideration of all these factors a unit size of 30MW in a two

unit configuration has been selected.

7.8 RECOMMENDATIONS

Installed capacity optimisation is based on the energy generation,

which may be carried out on the project cost basis also, as the project

components are firmed up based on the detailed studies. The

development of scheme with respect to other upstream and

downstream development in the Tidong may also be studied.

7/30/2019 Tidong

58/162

TIDONG-I HEP

CHAPTER 8

ELECTRO MECHANICAL WORKS

8.1 GENERAL

Tidong-I Hydel Project utilizes the flows of Tidong khad, a tributary of

Satluj river and is located in Kinnaur Distt. of Himachal Pradesh . A

net head of 511.70 m. has been utilized to generate 60 MW of power

at Tidong-I power house .

The project shall utilize waters of Tidong khad with a design discharge

of 13.45Cumecs.

The salient features of Tidong-I HEP are as under:-

. Design discharge 13.45 Cumecs

Net Head 511.70Meters

Installed capacity 60 MW

No. and size of units 2 units of 30 MW each.

Type of Power House Underground.

Cost of Electrical Works:-

P-production------- Rs. 6289.23 Lacs.T- Transmission--- Rs. 1086.26 Lacs.

8.2 SCOPE

This project report incorporates the detailed abstract of cost under the

heading P- production (generating plant Equipment) and T-

transmission (Transmission lines for evacuation of power). Detailed

analysis in the form of various Annexures have been attached to this

report. The cost estimates are based on the rates prevailing during the

current year i.e. 2003-2004.

7/30/2019 Tidong

59/162

TIDONG-I HEP

8.3 POWER HOUSE

The power house site is located on the right bank of Satluj river and isapproachable from Kalka (nearest broad gauge Railway station)

The underground power house ( 89.5 m (L) x 15 m(W) x 32.15 m(H))

will have 2 generating units of 30 MW each along with all the auxiliary

facilities such as cooling water / potable water supply system, fire

protection system, compressed air supply , oil system, ventilation and

Air conditioning system etc.

The control room , LT room, Battery room, air conditioning Plant,

Offices, cable spreading area will be accommodated in different floors

adjacent to the machine hall and will increase the length of power

house cavity by 15m. The service bay shall be located on the opposite

end of the machine hall. Provision for the lubricating oil handling plant,

the water treatment and filtration plant and store etc. has also been

made. The generator transformers will be located in a separate cavity

and will be connected to generating units through 11 kV bus ducts. On

a floor just above the transformers , 220 kV GIS equipment shall be

accommodated.

8.4 MECHANICAL EQUIPMENT

8.4.1 Turbines

The vertical shaft , 4 jet Pelton turbine of 30.92 MW capacity with a

rated synchronous speed of 428.56 rpm has been found to be suitable

in view of the over all economy of the power house. Each turbine shall

be provided with suitable oil pressure unit, Electro hydraulic governor

and other requisite control equipment.

7/30/2019 Tidong

60/162

TIDONG-I HEP

8.4.2 Governor

Since Tidong-I power house will be connected with 400Kv/220KVJangi pooling point and shall also be operated as peaking station in

tandem with Tidong II project , it is of great importance that the

governor accuracy and sensitivity is of high order so as to ensure that

all the regulators behave in the same way for any change in the

system load. Thus to avoid mutual hunting and over regulation , it is

proposed to provide Electro Hydraulic governor. The governing system

for each unit will have an individual oil pressure system consisting of oil

to air mixer and an oil tank with two pumps as well as the automatic

control equipment. Speed etc. would be indicated both on the governor

cubicle and on the unit control board to facilitate supervision of

operation of the unit. The controls would include provision for

emergency shut down of unit in case of :-

Loss of Pressure in the oil pressure vessel of Governor oil system.

Excessive temperature rise in Bearing.

Excessive speed rise of the unit.

Electrical faults.

8.4.3 Main Inlet Valves

A main inlet valve of the Spherical type would be provided at each

turbine inlet for maintenance of the turbine and for emergency

isolation of the turbine in the event of governor failure. Each valve shallbe actuated by means of servomotor which shall be fed from an

independent oil pressure unit.

Each valve unit shall constitute a complete independent unit with its

own operating system for opening and closing, which will be connected

to the automatic start and stop sequence of the respective turbine unit.

7/30/2019 Tidong

61/162

TIDONG-I HEP

8.4.4 Cooling Water And Fire Protection System

A pumping system would be provided to supply adequate quantity ofwater from the tail race for cooling of the turbine and generator

bearings, generator air coolers and selected plant services.

Water for fire protection would be taken from an elevated reservoir

providing both reliable operation and ample capacity to fight fire in the

power house. A back up water supply to this reservoir would also be

provided.

8.4.5 Potable Water And Sanitary Drainage