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50 000 MW HYDROELECTRIC INITIATIVE
Government of India
Ministry of Power Central Electricity Authority
180 MW BAJOLI-HOLI HYDRO-ELECTRIC PROJECT HIMACHAL PRADESH
Preliminary Feasibility Report
(DRAFT COPY)
JUNE, 2004
Consultant: Himachal Pradesh State Electricity Board ( H.P.Government Undertaking )
INDEX
SR.NO. DESCRIPTION PAGE
CHAPTER-I SUMMARY I-1 TO I-8
CHAPTER-II BACKGROUND INFORMATION II-1 TO II-3
CHAPTER-III PROJECT AREA III-1 TO III-2
CHAPTER-IV TOPOGRAPHIC AND GEO-TECHNICAL
ASPECTS IV-1 TO IV-8
CHAPTER-V HYDROLOGY V-1 TO V-38
CHAPTER-VI CONCEPTUAL LAYOUT & PLANNING VI-1 TO VI-10
CHAPTER-VII POWER POTENTIAL STUDIES VII-1 TO VII-28
CHAPTER-VIII POWER EVACUATION VIII-1 TO VIII-9
CHAPTER-IX ENVIRONMENTAL ASPECTS IX-1 TO IX-35
CHAPTER-X INFRASTRUCTURE X-1 TO X-6
CHAPTER-XI CONSTRUCTION PLANNING &
SCHEDULE XI-1 TO XI-6
CHAPTER-XII COST ESTIMATE XII-1 TO XII-36
CHAPTER-XIII ECONOMIC EVALUATION XIII-1 TO XIII-14
CHAPTER–I SUMMARY
1.0 SUMMARY
The Bajoli-Holi Hydro-electric Project has been contemplated as a run of
river scheme on river Ravi in Chamba District of H.P. It is an upstream
development of Kutehr Hydro-electric Project (260 MW). This project
comprises a diversion barrage near village Bajoli, intake structure, one no
feeder tunnel, an under ground desilting arrangement to divert 71.74
cumecs of water through a 5 m dia, 14600 m long modified horse shoe
shaped head race tunnel, a surge shaft 12m dia. and ± 96m heigh, a
pressure shaft 4 m dia trifurcating near power house to 2.30 m dia each and
a underground power house near village Barola on the right bank of river
Ravi to accommodate three vertical axis Francis turbines to generate 180
MW (3 x 60 MW) of power.
1.1 GENERAL PROJECT FEATURES
LOCATION
State Himachal Pradesh
District Chamba
River Ravi
Diversion barrage Near village Bajoli
Power house site Near village Barola
HYDROLOGY
Catchment Area at intake site 760 Sq. km.
Snow catchment 372 Sq. km. above El. 4000m
I - 2
Mean annual rainfall at Bharmour 899 mm
Design flood 3050 cumecs
DIVERSION STRUCTURE
Type Gated Barrage
Length of Barrage at top ±100.00 m
Max. height from R.B.L 33.00 m
Top El. of Barrage 2018.00 m
Average River Bed level. 1985.00 m
FRL 2015.00 m
MDDL 1993.00 m
SPILLWAY
Design flood 3050 cumecs
Type Gated spillways with radial gates
Nos. of spillways, Crest elevation 6 Nos , El 1987.00
Size of gated spillway 6m x 8m, each.
Energy dissipation Stilling basin
Down stream bed level El. 1975m
INTAKE STRUCTURE
Type Semi circular
Crest level El. 1990.00 m
No. & size of opening 8 No., 5.50 mx3.0 m
FEEDER TUNNEL
No. 1
Size and type 6.00m dia, Circular concrete lined
I - 3
Velocity 3.17m/sec
Length ± 300m
Design discharge from intake 89.67 cumecs
DESANDING BASIN
Type Underground.
No. of basins 2 nos.
Length of each basin 380m
Size of basins Width 13.00m, Depth 19.60 m
Minimum particle size to be removed 0.2mm
Flushing tunnel, size 4.00m, D-Shaped
Flushing tunnel, length ± 1000 m
HEAD RACE TUNNEL
No. One
Size & Shape 5m diameter, modified
Horse shoe concrete lined
Length ±14600 m
Design discharge 71.74 cumecs
Slope 1 in 409 m
Velocity 3.65m/sec
SURGE SHAFT
Type Open to sky, Restricted orifice type
Size 12.00 m dia cricular
Orifice 2.15 m dia
Maximum upsurge level El.± 2043 m
Minimum down surge level El.± 1960 m
Bottom level El±.1954 m
I - 4
Top level El.± 2050 m
PRESSURE SHAFT
Type Underground
Size:
Main 1 No., 4m dia, ± 440 m long
Branches 3 Nos., 2.30 m dia, ± 20 m long each
Velocity 5.74 m/sec.
POWER HOUSE
Type Underground
Installed capacity 180 MW
No. and capacity of unit 3 Nos. 60 MW
Size of machine hall 50 m x 17 m x 35 m
Type of turbine Francis turbine
Speed of turbine 500 RPM
Gross Head 308 m
Normal tail water level 1700 m
Net operating head for design discharge 278 m
Peaking duration 3 hrs .
TAIL RACE TUNNEL
Shape D-Shaped
Dia 5.00 m
Length ± 450 m
SWITCH YARD
Type Surface
I - 5
Size 170 (L) x 35 m (W)
TRANSMISSION LINE
No. of circuits S/C Line
Length of each 35 km.
Voltage 220 KV
POWER GENERATION
Installed capacity 3x60 MW
Annual energy generation
90% dep. Year 762.98 GWH
50% mean year 861.37 GWH
1.2 STUDIES UNDERTAKEN
The Layout of the Bajoli-Holi HEP has been finalized keeping in view
various studies undertaken by HPSEB from time to time to conceive a most
economical and viable scheme on Ravi river.
Proposal-I
This proposal-I envisages diversion structure near village Bajoli water
conductor system comprising 12200 m long HRT on right bank of river
Ravi and power house site near Kala nallah with tail race tunnel of 3500 m
length and losing the head approximate 20 m therefore resultant losing the
capacity of power house. Hence this proposal has been rulled out due to
constraints of high inverse gradient of access tunnel to power house and its
construction difficulties.
I - 6
Proposal-II
Present proposal of Bajoli Holi HEP (180 MW) is based on head available
between village Bajoli and Barola. The proposed scheme envisages
diversion of in flows of river Ravi near village Bajoli and 14600 m water
conductor system proposed at right bank and underground power house
near Barola village (opposite of village Holi). This proposal will generate
762.98 Gwh in 90% dependable year.
The alternative proposals are shown in Plate 1.1.
I - 7
1.3 COST ESTIMATE & FINANCIAL ASPECTS
COST ESTIMATE
Capital cost of the project (At Price level June. 2004):
Civil works Rs. 415.01 Crore
Electrical works
(P-Production) Rs. 165.61Crore
T-Transmission Rs. 36.03 Crore
Total Rs 616.64
Capital cost of Generation Rs. 649.22 Crore
(Including IDC Rs. 68.60Crore)
Loan 70% Rs. 454.45Crore
Equity 30% Rs. 194.76Crore
Capital cost at purchase center Rs. 688.35 Crore
(Including IDC Rs. 71.70Crore)
Loan 70% Rs. 481.84Crore
Equity 30% Rs. 206.50Crore
FINANCIAL ASPECTS
Cost of generation per MW of
Installed capacity Rs. 3.23Crore
Levelized tariff at PH Rs. 1.60/Kwh
Bus bars in 90% dep. Year
I - 8
Levelized tariff at purchase center Rs. 1.93/Kwh
in 90% dep. Year
Energy available for sale in 90% dep. Year 753.82 GWH
(Auxiliary consumption @ 0 .7% &
Transformation losses @ 0.5%).
at power house bus bars
I - 9
PARA DESCRIPTION PAGE
1.0 SUMMARY I-1
1.1 GENERAL PROJECT FEATURES I-1 TO I-5
1.2 STUDIES UNDERTAKEN I-5 TO I-6
1.3 COST ESTIMATE & FINANCIAL ASPECTS I-7 TO I-8
PLATE 1.1 ALTERNATIVE PROPOSAL
I - 10
SALIENT FEATURES LOCATION State Himachal Pradesh District Chamba River Ravi
Diversion barrage Bajoli Power house site Barola (Opposite village Holi) HYDROLOGY Catchment Area at intake site 760 Sq. km. Snow catchment 372 Sq. km. above El. 4000m Mean annual rainfall at Bharmour 899 mm
Design flood 3050 cumecs DIVERSION STRUCTURE
Type Gated Barrage Length of Barrage at top ±100.00 m
Max. height from R.B.L 33.00 m Top El. of Barrage 2018.00 m Average River Bed level. 1985.00 m
FRL 2015.00 m MDDL 1993.00 m
SPILLWAY Design flood 3050 cumecs Type Gated spillways with radial gates Nos. of spillways, Crest elevation 6 Nos , to 1987.00 Size of gated spillway 6m x 8m, each. Energy dissipation Stilling basin Down stream bed level El. 1975m INTAKE STRUCTURE
Type Semi circular Crest level El. 1990.00 m No. & size of opening 8 No., 5.50 mx3.0 m FEEDER TUNNEL No. 1 Size and type 6.00m dia, Circular concrete lined Velocity 3.17m/sec Length ± 300m Design discharge from intake 89.67 cumec DESANDING BASIN Type Underground.
No. of basins 2 nos. Length of each basin 380m Size of basins Width 13.00m, Depth 19.60 m Minimum particle size to be removed 0.2mm Flushing tunnel, size 4.00m, D-Shaped Flushing tunnel, length ± 1000 m
HEAD RACE TUNNEL No. One Size & Shape 5m diameter, modified
Horse shoe concrete lined Length ±14600 m Design discharge 71.74 cumecs
Slope 1 in 409 m Velocity 3.65m/sec SURGE SHAFT Type Open to sky Restricted orifice type Size 12.00 m dia cricular Orifice 2.15 m dia Maximum upsurge level El.± 2043 m Minimum down surge level El.± 1960 m Bottom level El±.1954 m Top level El.± 2050 m PRESSURE SHAFT/PENSTOCK Type Underground/ Surface Size: Main 1 No., 4m dia, ± 440 m long Branches 3 Nos., 2.30 m dia, ± 20 m long each Velocity 5.74 m/sec. POWER HOUSE Type Underground Installed capacity 180 MW No. and capacity of unit 3 Nos. 60 MW Size of machine hall 50 m x 17 m x 35 m Type of turbine Francis turbine
I - 11
Speed of turbine 500 RPM Gross Head 308 m Normal tail water level 1700 m Net operating head for design discharge 278 m Peaking duration 3 hrs . TAIL RACE TUNNEL Shape D-Shaped Dia 5.00 m Length ± 450 m SWITCH YARD Type Surface Size 170 (L) x 35 m (W) TRANSMISSION LINE No. of circuits S/C Line Length of each 35 km. Voltage 220 KV POWER GENERATION Installed capacity 3x60 MW Annual energy generation 90% dep. Year 762.98 GWH 50% mean year 861.37 GWH
CHAPTER – II BACKGROUND INFORMATION
2.0 BACKGROUND INFORMTION
2.1 GENERAL INFORMATION
Hydel potential of Ravi basin in H.P. has been identified as 2323.02 MW as
indicated in Plate-I for this basin. Bhuri Singh (450 Kw), Bharmour (20
Kw), Gharola (50 Kw), Baira Suil HEP (198 MW), Chamera Stage-I (540
MW) & Sal Stage-II ( 2 MW), Chamera Stage-II (300 MW) are under
operation at present. The construction works on Hibra (231 MW) renamed
as Chamera Stage-III have also been taken up by Govt. of India through
NHPC. Construction work of Holi HEP (3 MW) has been got completed by
the HPSEB on turn key basis & commissioning of the project is expected
shortly.
MOU’s have been signed with IPP/Central Agency for the projects like Sai-
Kothi, Hibra HEP renamed Chamera HEP Stage-III. Presently, two projects
namely Chamba HEP 126 MW and Bajoli Holi HEP (180 MW) are under
investigation in Ravi basin. The project like Harsar, Kugti, Bharmour,
Budhil, Sal Stage-I, Suil and Kutehr, Bara Bhangahal (170 MW), Chanju
Stage-I (25 MW), Chanju Stage-II (17 MW) & Baira Bihali (15 MW) are
yet to be taken up for investigation. Presently, two projects namely
Chamba HEP 126 MW and Bajoli Holi HEP (180 MW) are under
investigation in Ravi basin.
Bajoli Holi HEP (180 MW) is a upstream development of Kutehr HEP on
right bank of river Ravi to generate 180 MW of power by constructing a
diversion structure near village Bajoli and underground power house near
village Barola..
II - 2
2.2 POWER SCENARIOS & EXISTING INSTALLATIONS
2.2.1 POWER ABSORPTION IN NORTHERN REGION
2.2.2 POWER LOAD DEVELOPMENT
The Northern Region comprises the states of Himachal, Haryana, Punjab,
Rajashtan, Jammu & Kashmir, Uttar Pradesh, Uttranchal and Union
territories of Delhi and Chandigarh. The Northern Regional Power Grid
comprises the power system controlled by the Electricity Boards of above
states/Union territories and Bhakhra Beas Management Board.
The Power system in this region is now operating in an inter-connected and
co-ordinated manner. Even in co-ordinated operation of existing hydro,
nuclear and thermal power stations, including benefits from the ongoing
projects and as well from the new schemes cleared by CEA, the Northern
region is expected to face severe power deficits in the 10th Five Year Plan.
The CEA schemes for preparation of PFR under “50,000 MW Hydro-
electric Initiative” schemes launched by the Hob’ble Prime Minister of
India are as under:-
Sr.No. Name of scheme River/Basin
1 Gharopa (114 MW) Beas
2 Gondhala (144 MW) Chenab
3 Bardang (114 MW) -do-
4 Chhatru (108 MW) -do-
5 Khoksar (90 MW) -do-
6 Chamba (126 MW) Ravi
7 Jangi-Thopan (480 MW) Satluj
8 Luhri (465 MW) -do-
9 Tidong-I (90 MW) -do-
10 Tidong-II (90 MW) -do-
11 Yangthang Khab (261 MW) -do-
12 Thopan Powari (402 MW) -do-
13 Bajoli-Holi (180 MW) Ravi
II - 3
2.3 NECESSITY OF THE PROJECT AND RELATED ASPECTS
From the growth of peak demand and anticipated installed generation
capacity on the basis of schemes proposed for benefits under
construction/consideration during 10th and early 11th Five Year Plan period,
it is observed that power supply position in the Northern region would
become all the more acute from the start of 10th Five Year Plan and power
region shortages would have to be faced unless additional schemes are
taken up immediately and implemented to derive timely benefits. The most
important source of power development in the Northern region is its
abundant hydro resources located in Himachal Pradesh, Uttar Pradesh,
Uttranchal and Jammu & Kashmir. Priority would have to be given to the
development of these untapped resources because of the following
distinguishing features of the hydro stations.
i) They estimate the most economic source of power development.
ii) They provide the cheapest source of peaking capacity.
iii) They enable improvement in the utilization of thermal/nuclear
power stations in the region.
iv) They provide much needed operation & flexibility to the system.
Thus, there is an urgent need of rapid hydro potential exploitation for
providing additional generation capacity in the Northern region. Among the
various sites, available for hydro development, Bajoli Holi Hydro-electric
Project is considered very attractive from point of view of deriving benefits
during 11th Five Year Plan. The diversion site is located on Chamba-Holi
road and 7 Km from village Naya Gaon. Power house site is to be
connected by providing RCC bridge on river Ravi near village Barola. The
existing communication facilities will be of considerable utility in cutting
down the pre-construction time and costs.
II - 4
II - 5
PARA DESCRIPTION PAGE
2.0 BACK GROUND INFORMATION II-1
2.1 GENERAL INFORMATION II-1
2.2 POWER SCENARIOS & EXISTING
INSTALLATIONS
II-2
2.2.1 POWER ABSORPTION IN NORTH REGION II-2
2.2.2 POWER LOAD DEVELOPMENT II-2
2.3 NECESSITY OF THE PROJECTS AND
RELATED ASPECTS
II-3
PLATE - 1 MASTER PLAN OF RAVI BASIN
CHAPTER - III PROJECT AREA
3.0 PROJECT AREA
3.1 DESCRIPTION OF PROJECT INCLUDING RIVER SYSTEM
Himachal Pradesh has the unique distinction of providing water both to the
Indus and Ganges basins. The major river systems of the region are
Chandra- Bhaga or Chenab the Ravi,the Beas the Satluj and the Yamuna.
These perennial rivers are both snowfed and rain fed and are protected by
fairly extensive cover of natural vegetation.
Bajoli-Holi hydroelectric project is located in Distt. Chamba of Himachal
Pradesh and the project involves the construction of diversion barrage at
latitude 32°16'53’’ & longitude 76°40'45’’ and power house at latitude
32°20'31’’ & longitude 76°32'37’’. This project has been contemplated as
upstream development of Kutehr HEP (260 MW). Max. gross head of 308
m is available for generation of 180 MW power in an underground power
house near village Barola. This project comprises a diversion barrage near
village Bajoli, intake structure one No. feeder tunnel, an under ground
desilting arrangement to divert 71.74 cumecs of water through a 5 m dia,
14600 m long horse shoe head race tunnel, a surge shaft dia 12m and ±
96m height, a pressure shaft 4 m dia trifurcating near power house to 2.30
m dia each and a underground power house near village Barola on the right
bank of river Ravi to accommodate three vertical axis Francis turbines to
generate 180 MW (3 x 60 MW) of power.
The annual power generation from the project in 90% dependable year and
50% mean year will be 762.98 Gwh and 861.37 Gwh respectively.
III -
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3.2 SOCIO-ECONOMIC AND OTHER ASPECTS
The economy of the Himachal Pradesh is predominantly dependent on
agricultural and allied sectors. The per capita income of Himachal Pradesh
in 2000-01 was Rs. 10,942.00 as compared to Rs. 16487.00 at the national
level. The electric power being a vital and essential infrastructure has a
significant role to play in economic upliftment of the state. The
construction of project will provide employment to the local people. When
completed, it will be another step towards realization of the dreams of the
state and exploiting its power potential for heralding an era of progress and
prosperity for not only of Himachal Pradesh but for the entire northern
region.
III -
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III -
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PARA DESCRIPTION PAGE
3.0 PROJECT AREA III-1
3.1 DESCRIPTION OF PROJECT INCLUDING RIVER
SYSTEM
III-1
3.2 SOCIO-ECONOMIC & OTHER ASPECTS III-2
CHAPTER-IV TOPOGRAPHIC & GEO-TECHNICAL ASPECTS
4.0 GENERAL
The preliminary geotechnical studies of Bajoli Holi HEP have been got carried
out from GSI and a detailed appraisal note sent by Sh. S. Chopra, Director, DPR
Unit, Geological Survey of India, New Delhi is as under:-
4.1 INTRODUCTION
The Central Electricity Authority (CEA), with a view to fill the gap between
supply and demand in the field of power have embarked on an exercise to assess
the balance hydroelectric potential in the country and rank the schemes thus
identified in various parts of the country in different river basins. As a part of this
exercise, 162 schemes with probable installed capacity of 50,600 MW and located
in various river basins spread over 16 states have to be taken up for preparation of
Pre Feasibility Reports (PFRs) in the first phase. The schemes found feasible are
proposed to be taken up for further development in X and XI Five Year Plans.
The proposed Bajoli Holi Hydroelectric Project is one such scheme identified in
Ravi Basin in Chamba district of Himachal Pradesh State. Bajoli Holi
Hydroelectric Project is a run of the river scheme that envisages the construction
of a 30 m high diversion barrage across the river Ravi, 200 m downstream of its
confluence with Channi nallah (32o16’53”N:76o40’45”E; 52 D/11), about 14.6
km long water conductor system and an underground power house on the right
bank of Ravi, near village Barola (32o20’31”N:76o32’37”E; 52 D/11). The
proposed power house would have installed capacity of 180 MW.
IV -
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4.2 REGIONAL GEOLOGY
The area around the proposed projects is located in Lesser Himalaya in Ravi
Basin and is characterised by sharp crested ridges and deeply dissected valleys.
The main drainage in the area is provided by the river Ravi which originates in
Bara Bhangal area. The river initial reaches up to Khada Mukh between Tipri –
Chamba and Raj Nagar Khas flows along the regional strike of rocks and cuts
across the strike between Khada Mukh and Tipri. The influence of lithology and
structure is clearly evident an drainage by its semidenritic and rectangular pattern
Geologically the region exposes rocks ranging in age from early Proterozoic to
Mesozoic. The rocks of the area are extensively covered by slope debris, fluvial
terraces and fan the deposits of Quaternary recent origin. The statigraphic
succession in the area is given by the officers of GSI and Malviya et al (1991) is
given below:
Age Group Formation Lithology
Triassic -- Khalel Limestone with calcareous
shale and ferruginous clay
Upper Permian -- Salooni Calcareous sandstone
arenaceous shaly limestone,
slate.
Lower Permian -- Panjal Traps Green massive amygdaloidal
basic lava flows
Late Proterozoic Vaikrita Katari Gali Dark grey slate micaceous
sandstone, quartzite, calcareous
siltstone limestone
Manjir Dimictite shale slate sandstone,
limestone
Chamba Slate, phyllite, carbonaceous
slate subordinate quartzite
IV -
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In the area around the proposed projects, the rocks belonging to Varikrita Group
are exposed in the valley of Ravi river. The rock belonging to Chamba Formation
of Vaikrita Group include an assemblage of slates phyllite, carbonaceous slate and
subordinate quartzites. The rocks of Chamba Formation are succeeded by an
assemblage comprising pebbly slate/dimictite, phyllite, shale, sandstone and
limestone belonging to Manjir Formation. The rocks of Manjir Formation are in
turn succeeded by the rocks belonging to Katari Gali Formation which include an
interbedded sequence of the slate, quartzite with limestone and magnesite. The
bands of limestone, calcareous shale and ferruginous chart belonging to Khalel
Formation of Triassic age have been reported to be occurring in east and north of
the arc of proposed projects.
4.3 STRUCTURE AND TECTONICS
Tectonically, the Chamba area is located in Main Himalayan Tectonic Belt
bounded by Indus Suture Zone(ISZ) in north and MBF-I in south (Kumareta
1989). This belt exposes the lithostratigraphic units ranging in age from
Proterozoic to Quaternary. The most important tectonic plane in this belt is Main
Centre Thrust. However, its position between the rivers Beas and Chenab is not
well defined. The other important tectonic feature in this belt is Vaikrita
Thrust(VT). In addition to these tectonic planes following the Himalays trend, a
number of transverse fault dissect the rocks in the area, the prominent ones being
Sundernary Fault, Kishtwar Fault, Ravi Tear and a few other transverse
lineaments which have been picked up with the help of satellite imageries. The
tectonic zone south of Main Himalayan Belt is the Frontal Fold Belt demarcated
by HFB-I in the north and Foot Hill Thrust in south. The structure elements
recorded in the area are both primary and secondary. The primary structures
include bedding and current bedding. The secondary structures include cleavage
and foliation, joints, folds, faults and lineation developed during metamorphic and
tectonic phases. The bedding is marked by colour bands and contacts between
arenaceous and argillaceous beds. The strike of bedding of the rock formations
IV -
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generally various from N200W-S200E to N80O W – S80O E with moderate to low
dips towards NE or SW. There are two sets of cleavages recorded in the rocks i.e.
slaty cleavage fracture cleavage. The trend of these varies between NNE-SSW
and WNW – ESE. The slaty cleavage showing NW-SW Himalayan trend in the
metasedimentary rocks of the area represents axial plane cleavage of folds F1
(Datta & Singh, 1973). In general it is parallel to the bedding of the formations.
The pebbles of Manjir Formation are deformed and their shape indicates these
have been flattened on cleavage plane. The fracture cleavage is parallel F2 folds
that have folded bedding and slaty cleavage. The rocks of the area are jointed and
many of the joint sets are common to all the rocks formations. Prominent joint
sets trend NW-SE, NE-SW and E-W and have moderate to steep dips in general
4.4 SEISMOTECTONIC AND SEISMICITY
From seismotectonic point of view, the area under reference is located on the
western fringe of Kangra Seismic Block (Narula,1991) which is bound by Ravi
Tear in west and Sundernagar fault in east. The litho tectonic packets of the
Himalayan Orogenic Belt are poorly metamorphosed lithol-units of the Tethyan
sequence , high and low grade assemblages of the Central crystalline and other
crystallines and Lesser Himalayan belt respectively along with granitoids and
basic volcanics (Narula et al., 2000). The southern fringe of the Himalayan belt is
occupied by cover rocks of the Frontal Belt. Further south, the Quaternary cover
is represented by alluvial fill along the foredeep and peri-cratonic fills on
attenuated continental crust on northern and southern sides, respectively of Delhi-
Sargoda Ridge.
Within the Himalayan belt, the northernmost conspicuous structural element is the
Main Central Thrust (MCT). From Manali towards east throughout the entire
Himalaya almost up to the eastern syntaxis this is considered as one of the most
important tectonic surfaces. However, NW of Manali, it is not clearly discernible.
Further south, within the lesser Himalayan package, the other important tectonic
IV -
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surface is Vaikrita Thrust (VT). This Lesser Himalayan Belt is separated from the
Frontal belt by the Main Boundary Thrust (MBT). The southern limit of the
Frontal Belt is marked by the Main Frontal Thrust (MFT). Within MBT and
MFT, the belt is traversed by several subsidiary thrusts viz Jawalamukhi Thrust
and Drang Thrust. Evidences of neotectonic activity have been documented at
several places along MBT and in western parts of Jawalamukhi Thrust. The
Frontal Belt package is affected by several regional scale folds, of which
Mastgarh and Paror anticlines are prominent.
In addition to the structural discontinuities sub parallel to Himalayan trend, there
are a number of faults lineaments transverse to this fold-thrust belt. The
Sundarnagar Fault (also known as Manali Fault) is a dextral transverse structures
which extends from Higher Himalayas to Frontal Belt. The Ropar Tear is
considered to be continuation of the Sunder Nagar fault.
A total of 99 seismic events of magnitude > 4.0 have been recorded in the area.
Out of these 20 events have magnitude >5.0 and are mostly confined to depths
less than 40Km. Event having magnitude between 4.0 and 5.0 are prevalent in the
area. Seismic activity in mainly concentrated along the Himalayan Belt
particularly around Chamba. This sector with maximum clustering of seismic
events represent part of Kangra Seismic Zone that continues towards N. Out of 20
events of magnitude >5 about 18 events define this zone. In this part of the
Himalaya, 4 events having magnitude > 6 have been recorded. Out of these, 3
events lie on MBT, which include the famous Kangra Earthquake of 1905. Six
earthquakes in this area have caused considerable damage. The earliest is the
Kangra Earthquake of 4th April, 1905 having Ms = 8.0, Chamba Earthquake of
22nd June 1945 also caused considerable damage to the property. Dharamshala
Earthquake of 14th June, 1978, Dharamshala of Earthquake 26th April, 1986 and
Chamba Earthquake of 24th March 1995 are other major earthquakes that caused
considerable damage in the area. Keeping in view the seismotectonic set up and
seismic status of the area, it has been kept in Zone-V as per. Map of India
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showing Seismic zones (IS: 1893 (Part-I)-2002). Therefore, it is recommended
that suitable seismic coefficient be determined for site and incorporated in the
design of appurtenant structure of the projects.
4.5 GEOTECHNICAL APPRAISAL
The geological map of the area indicates that almost all the appurtenant structures
of the proposed Bajoli Holi Hydroelectric Project are likely to be located on the
rocks belonging to Katari Gali Formation which could be good foundation as well
as excavation media except for reaches where weathering is deep, carbonaceous
slates are en countered and rocks are fractured or sheared. The exploration at the
site of Kutehr Project located downstream of this scheme indicates that thick
overburden can be expected in the riverbed. Therefore it is suggested that the site
for dam and type of structure be selected after assessing the depth of overburden
in the river bed and on abutments.
The 14.6 km long HRT of the proposed Bajoli Holi Hydroelectric Project is likely
to encounter slates, micaceous sandstone, quartzite and limestone belonging to the
Katari Gali Formation in the initial reaches and dimictite, shale, sandstone and
limestone belonging to Manjir Formation in the final reaches. These rocks are
expected to be fair to good tunnelling media in general except in the reaches
where slate/phyllite are encountered. The problem may be more acute where
these are water charged. Poor rock conditions may also be expected in the reaches
where local faults/shears are encountered. It is suggested that adequate rock
cover over HRT may be provided, especially in the reaches where it negotiates
cross drainages. The perusal of preliminary layout of the scheme indicates that no
provision of intermediate construction adit has been kept along this 14.6 km long
HRT. It may lead to difficult construction conditions. It is suggested that efforts
may be made to provide at least one intermediate construction adit to facilitate
construction.
IV -
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The powerhouse location exposes dimictite, shale, slate and sandstone belonging
to Manjir Formation. It is suggested that the final selection of powerhouse site be
made depending on availability of bed rock in the foundation and adequate space
to host structure and its appurtenants without disturbing the hill slopes. If such a
site is not available on the surface, the structure may be designed as underground
one. The area is located in Zone V as per Map of India Showing Seismic Zone
[IS – 1893(Part – I) 2002]. Therefore suitable seismic coefficient be in corporate
in design of apppurtenants of the project. This geotechnical appraisal is based on
regional geological set up without field visit to the project site.
REFERENCES
1. Datta, R.K. and Singh, Surinder (1975). Report on geological mapping in parts of
Chamba, District Himachal Pradesh, unpubl, GSI Report, FS 1971-72.
2. Kumar, G., Sinha, Roy, S. and Ray, K.K. (1989). Structure and Tectonics in
Himalayan, GSI, spl Publ. 26 pp 85-118
3. Malviya, A.K. Jamwal, J.S. Kachker, A.K. and Pande A.C. (1991) Report on
lithostratigraphy, standardisation and regional correlation of the rocks of Tethyan
Realm of NW Himalaya, Unpublished GSI compilation for F.S. 1982-83 to 1988-
89.
4. Narula, PL (1991). Seismotectonic Evaluation of NW Himalayan, Unpublished
GSI Report.
5. Narula, P.L., Acharayya, S.K. and Banerjee, J. (2000) Seismotectonic Atlas of
India and its Environs. Pub. Geol. Surv. Ind..
IV -
8
IV -
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PARA DESCRIPTION PAGE
4.0 GENERAL IV-1
4.1 INTRODUCTION IV-1
4.2 REGIONAL GEOLOGY IV-2 TO IV-3
4.3 STRUCTURE & TECTONICS IV-3 TO IV-4
4.4 SEISMO TECTONICS AND SEISMICITY IV-4 TO IV-6
4.5 GEO-TECHNICAL APPPRAISAL IV-6 TO V-7
REFERENCES IV-7
PLATE-4.1 GEOLOGICAL MAP OF PROJECT IV-8
CHAPTER – V
HYDROLOGY
5.1 LOCATION
The Ravi is a major river of the Indus Basin originating in the Himalayas
from the Bara Bangahal branch of the Dhaula-Dhar range. Bara-Bangahal
branch comprises of snow covered peaks at heights ranging from 3050 m
to 5800 m, above mean sea level.
Bajoli-Holi Hydro-electric Project is located on the river Ravi, between
the longitudes 76°40′45" to 76°32′37" and latitudes 32°16′53" to
32°20′31" in the Chamba Distt. of Himachal Pradesh.
5.2 TOPOGRAPHY AND CATCHMENT
5.2.1 TOPOGRAPHY
Lying mostly astride the main Himalayas and touching the Shiwaliks on
the southern fringe, the Ravi catchment area is rugged and covered with
the spurs of the high ranges. The Dhauladhar range separating the basin of
the Beas from that of the Ravi, the Pangi or Pir Panjal range dividing the
water shed between the river Ravi and river Chenab and Zaskar range
bifurcating the basins of the Chenab and the Indus, are the three well
defined snowy ranges, constituting the main topographical features of the
area.
The Dhauladhar range running in North-West direction, forms the
boundary between Mandi and Kullu Districts, at the point where it gives
off Bara Bangahal branch to join the mid Himalayas. It makes a sudden
bend west-ward and for the first time touches Chamba District, on the
southern border. From this point, it continues for about 50 Kms. forming
the boundary between Kangra and the Chamba Districts.
The Zaskar range is the direct continuation of the main Himalayan axis. It
runs in north west direction, divding Ladakh from Lahaul- Spiti and then
touches Chamba District, for a short distance along its northern border,
separating Chamba and Lahaul-Spiti from Zaskar.
The Pir Panjal range known as the Pangi range within the Chamba District
after separating Kullu from Lahaul-Spiti, enters Chamba district on the
western border of the Bara Bangahal and traverses the district from South-
East to North-West for more than 100 kms. On the North-Western border,
where the Pangi range leaves the territory, it gives off a branch to the
South-West called the Daganidhar which forms the boundary between
Chamba and Bhadrawah of Jammu and Kashmir. At its western extremity,
this branch is connected by a short ridge, in which the Padri and the
Chatardhar passes. Topographically, the Dagnidhar and the Chatardhar are
different sections of one continuous offshoot, forming with the Pangi
Range, the water shed between the Ravi and the Chander-Bhaga
(Chenab).
5.2.2 RIVER RAVI AND ITS TRIBUTARIES
It originates from Bara-Bangahal at an elevation of 4229 m above mean
sea level, approximately 150 Kms North-East of historical Chamba town.
The Ravi flows in steep gradient with series of loops & bends. In between,
main tributaries like Kalihan, Budhil, Tundah, Suil & Sewa contribute lot
of run-off to the Ravi. Bara-Bangahal comprises of snow covered peaks at
heights ranging from 3050 mtrs to 5800 mtrs above mean sea level.
The basin represents some remarkable physical features. The river flows
in a North-West direction for most of its course, rises in Baira-Balsio and
continues through Traila and Chanota to Ulans, where it is joined by two
of its major tributaries in the head reaches Viz. Budhil and Tundah.
Beyond this, upto Chhatrari, river flows through a narrow gorge where
after it opens out. After passing through Churi, Bagga, Mehla, Chamba
and Udaipur, the river approaches Rajnagar, then flows in narrow gorge to
Sherpur. The Suil river, the largest tributary, joins the Ravi upstream of
Chamera Stage-I Dam. The Sewa river flowing from the north joins the
Ravi near Khairi. It then bends to the South-West and striking the terminal
spurs of the Dhauladhar range, separates Chamba from Jammu and
Kashmir and finally leaves the territory of Himachal Pradesh up stream of
Ranjit Sagar Dam (Punjab).
Budhil nallah has its origin on the slopes of the mid Himalays near Kugti
pass. At Harsar, it receives on its left bank the small stream from sacred
lake of Mani-Mahesh, situated beneath the peak called the Mani-Mahesh,
Kailash at an elevation of 3952 m. It passes Village Bharmour at 15 Kms
downstream and soon afterwards meets the Ravi near Village Kharamukh.
Tundah nallah rises at Kalichtop pass, flows through Tundah valley and
joins the Ravi near Kharamukh. The right bank tributaries are bigger and
have more discharge as campared to the left bank tributaries except
Kalihan, which originates in Dhauladhar range on the left bank and
contributes a good discharge. Both Budhil & Tundah are about 54 Kms
long each .
5.2.3 CATCHMENT
The catchment area at Bajoli-Holi diversion site measures 760 Sq.Km. out
of which 372 Sq.Km is above 4000 m and is snowfed catchment. The
entire catchment comprises of mountaineous terrain with steep hill slopes
and is very thinly populated. The Ravi river after its origin from Bara-
Bangahal branch of Dhaula Dhar range, is mainly formed by the combined
waters of the three tributaries namely; Kalihan, Budhil & Tundah in the
head reaches. The Catchment areas of these three are:
1. Kalihan Nallah 158.75 Sq.Km
2. Budhil Nallah 555 Sq.Km
3. Tundah Nallah 305 Sq. Km.
The river bed slope is comparatively steeper in its upper reaches. The
equivalent slope of the Ravi upto Bajoli-Holi diversion site is 47.01
mtrs/Km.
5.3 METEOROLOGICAL CHARACTERISTICS
5.3.1 RAINFALL
There are, in all, thirteen non recording type rain gauge stations in the
catchment area of the river Ravi.
The normal annual rainfall & annual rainfall has been recorded in
millimeters at all these stations for the period 1960-2000 by the office of
Director, Land Records, Revenue Department (HP).
5.3.2 TEMPERATURE
There is no temperature record available at the proposed diversion site
while some record is available at Bharmour, which is ±15 Kms opposite
to proposed diversion site.
The relative humidity is generally high in the monsoon season, being over
90%. In the post monsoon and winter seasons, the humidity is less. The
summer is generally the driest part of the year.
5.4 HYDROLOGICAL CHARACTERISTICS
The Catchment area of the Ravi, above the proposed diversion site is 760
Sq. Kms, and is elongated leaf shaped as shown in drawing No. Bajoli
Holi-PR-2. In this reach, a good part of the catchment i.e. about 372
Sq.Km lies above the snow line i.e. 4000 m above M.S.L., which receives
moderate to heavy snowfall during winter.
The discharge of the Ravi and its major snowfed tributaries dwindles
down to lowest during winter months, from December to February and
starts increasing from February end due to the melting of snow. The bulk
contribution is in form of rainfall in the monsoon months. A few discharge
measuring stations namely; Bagga, Durgathi, Banthu, Tiyari, Bajoli and
Kutehr were set-up by HPSEB and a good data bank is available for these
sites.
5.5 HYDROLOGICAL STUDIES
5.5.1 DISCHARGE DATA AND WATER AVAILABILITY
The Discharge data of river Ravi at diversion site of Kutehr HEP (series
already approved by CWC) shown in Table 5.1 has been used to derive the
discharge data at diversion site of Bajoli-Holi HEP shown in Table 5.2.
The data w.e.f. June 1972 to May 1997 is the derived data whereas it is
actually observed data w.e.f. June 1997 to May 2003.
Based upon the daily discharge data, overall flow duration curve has been
developed (Plate 5.1). From this curve, it is seen that flow corresponding
to 90% and 50% availability works out to 12.50 cumecs and 29.17 cumecs
respectively. The design discharge of 71.74 cumecs is available for 25%
of the period. Flow duration curve for lean season (Dec. to Feb.) has also
been developed (Plate 5.2) and it is seen that flow corresponding to 90%
& 50% availability works out to 10.94 cumecs & 12.50 cumecs
respectively.
5.5.2 METHOD OF DISCHARGE OBSERVATION
i) GENERAL
Discharges of the Ravi at Durgathi, Banthu, Tiyari & Kutehr stream
gauging sites are measured by surface float method. Surface floats are
made up of well seasoned heavier type wood available locally. Heavier
floats are generally preferred so that its greater part would be submerged
in water thus reducing influence of the wind.
Cableways are installed across the river for the purpose of taking
observations. Two wire ropes are stretched across the river section, one at
the beginning and other at the end of the selected river reach for
conducting observations. The distance between two ropes known as float
race, is kept as 30 meters at discharge sites. The ropes are marked at 5 m
intervals to divide the river cross-section into different segments. The
centre line of the segment defines the path or track of the float. A third
rope is stretched 10 m upstream of test reach. A person taking
measurements rides in a small jhulla beneath the cable and drops floats in
different segments 10m upstream of the float race so that floats acquire
uniform velocity by the time they reach float race. Three floats are
dropped in each segment and mean of the time taken to traverse the float
race is recorded. The time of travel of test reach of only those floats which
follow their correct track is, recorded.
ii) CROSS SECTIONAL AREA OF FLOW
The cross-sectional area is divided into segments, each of 5 m width.
Cross-section is checked before and after monsoon period and after every
major flood in the river.
iii) MEASUREMENT OF VELOCITY
Measurement of Velocity =
Float Race
Time taken by float to cover the float race distance.
Mean velocity is generally determined by taking average of the velocities
measured at depths, 0.2 times and 0.8 times the total depth from the
surface. Float measurements represent surface velocity, as such, velocities
measured by float are multiplied by 0.89 to determine the mean velocity of
flow.
Mean velocity of flow = 0.89 x Surface velocity.
iv) COMPUTATIONS OF DISCHARGE
Mean velocities V1,V2,V3…………………………in each segment are
obtained after multiplying the surface velocities by 0.89. The velocities are
multiplied by area of cross-section of the corresponding segment to obtain
discharges in each segment. Summation of discharges in each segment
gives discharges in the river.
Q = ∑A1V1+A2V2+A3V3+………………….
= ∑Q1+Q2+Q3+……………………………
5.5.2 CO-RELATION STUDY
W.B. Langbein’s log deviation method has been used to obtain the co-
efficient of co-relation between discharges of river Ravi at Kutehr and at
Bajoli. The co-relation factors are as follows:
Monsoon period (June-Sept.) = 0.8665
Non-monsoon period = 1.0093
The computations have been shown in Table 5.3 & 5.4 respectively
From the above co-relation factors, it is evident that the discharges of river
Ravi at Kutehr & at Bajoli are consistent. The series for Kutehr HEP has
already been approved by your good office and the same has been used for
this period.
5.6 DESIGN FLOOD Design flood has been computed on the basis of flood estimation report for
western Himalaya Zone-7 and accordingly Hydrographs have been
prepared. The maximum flow due to rain contribution comes out to be
3029.99 cumecs which has return period of 1 in 50 years. Thus total
design flood has been adopted to be 3050 cumecs. The computations have
been shown as Annexure-V-1.
5.7 SEDIMENTATION ASPECTS
Detailed studies shall be carried out at the DPR stage.
5.8 90% DEPENDABLE YEAR As per the latest guidelines of CEA, the year wise unrestricted energy
generation has been computed for the period June-1972 to May,2003. The
energy so generated has been arranged in descending order. According to
Weibull’s relationship p=i/(n+1) where p= percentage exceeding of
occurrence, i=event number in descending order and n is the total number
of events, 90% dependable year and 50% mean year, have been computed.
The computations of power and energy generation have been shown in the
Table 7.1.
PARA DESCRIPTION PAGE 5.1 LOCATION V-1 5.2 TOPOGRAPHY AND CATCHMENT V-1 TO V-4 5.3 METEOROLOGICAL CHARACTERISTICS V-4 TO V-5 5.3.1 RAINFALL V-4 5.3.2 TEMPERATURE V-4 TO V-5 5.4 HYDROLOGICAL CHARACTERISTICS V-5 5.5 HYDROLOGICAL STUDIES V-5 TO V-8 5.5.1 DISCHARGE DATA AND WTER AVAILABILITY V-5 TO V-6 5.5.2 METHOD OF DISCHARGE OBSERVATION V-6 TO V-7 5.5.3 CO-RELATION STUDIES V-8 5.6 DESIGN FLOOD V-8 5.7 SEDIMENTATION ASPECTS V-8 5.8 90% DEPENDABLE YEAR V-9 TABLE-5.1 TEN DAILY AVERAGE DISCHARGE DATA OF RIVER
RAVI AT KUTEHR DIVERSION SITE V-10 TO V-13
TABLE-5.2 TEN DAILY AVERAGE DISCHARGE DATA AT BAJOLI HOLI DIVERSION SITE
V-14 TO V-17
TABLE-5.3 INFLOWS OF RIVER RAVI AT KUTEHR V-18 TABLE-5.4 INFLOWS OF RIVER RAVI AT BAJOLI V-19 TABLE-5.5 REGRESSION ANALYSIS BETWEEN DISCHARGES OF
KUTEHR AND BAJOLI (MONSOON PERIOD ) V-20
TABLE-5.6 REGRESSION ANALYSIS BETWEEN DISCHARGES OF KUTEHR AND BAJOLI( NON- MONSOON PERIOD )
V-21
ANNEXURE-V-1 DESIGN FLOOD COMPUTATION (UNIT HYDROGRAPH METHOD)
V-22 TO V-26
ANNEXURE-V-2 COMMENTS OF CWC ON DRAFT PFR AND REPLY THEREOF
V-27 TO V-32
PLATE-5.1 FLOW DURATION CURVE (OVERALL) V-33 PLATE-5.2 FLOW DURATION CURVE (LEAN PERIOD) V-34 PLATE-5.3 AREA CAPACITY CURVE V-35 PLATE-5.4 SYNTHETIC UNIT HYDROGRAPH V-36 PLATE 5.5 DESIGN FLOOD HYDROGRAPH V-37 PLATE 5.6 PLAN SHOWING RAIN GAUGE STATIONS, G&D SITES
AND SNOW GAUGE STATIONS V-38
CHAPTER – VI
CONCEPTUAL LAYOUT
AND PLANNING
6.0 CONCEPTUAL LAYOUT OF PROJECT COMPONENTS
6.1 FINALIZATION OF CONCEPTUAL LAYOUT
The proposed Civil Engineering Structures have been planned and designed
to divert and conduct 71.74 lacs of water, from river Ravi for generating
180MW of power in an underground power house by utilizing a gross head
of 308.00 m. The main works of the project comprise a diversion barrage,
intake, underground desanding basins for removing all particles down to
0.20mm size, 14600m long head race tunnel, a restricted orifice type surge
shaft and an underground power house to accommodate 3 vertical axis,
Francis turbines driven generating units each of 60 MW. After diversion,
all the civil engineering components have been kept underground keeping
in view the topography of the area. A brief geological site specific
feasibility note titled “Geo-technical appraisal” founded on preliminary site
inspection about each component is appended as Para 4.5 in chapter-IV
titled “Geo-technical Aspects”.
6.2 PRELIMINARY DESIGN FEATURES
6.2.1 BARRAGE
6.2.1.1 GENERAL
The slope of river at the diversion site u/s of Bajoli village is of the order of
1 in 55. Peak annual flood of river Ravi at diversion site has been adopted
as 3050 cumecs for design of spillways/barrage bays. Barrage 100m long
including abutments with crest level of barrage bays at El. 1987m & non
VI - 2
over flow section has been proposed to pass the estimated design flood at
FRL El. 2015.00m. The proposed barrage comprises 6 bays of 6.00m each
with 3.00m thick piers and is capable of passing the estimated design flood
even when one bay is considered inoperative during period of high floods.
The max. pond level/ FRL (El. 2015.00m) attained during winter months
shall also cater to peaking requirement . During high flood max. water level
to be attained has been proposed as 2016.00m. Radial gates in the barrage
bays shall be provided from top of crest El. 1987m to the bottom of RCC
breast wall El. 1995.00m spanning between the piers. The breast wall is
supported on the piers and is provided between El. 1995.00m and El.
2018.00m.
6.2.1.2 RESERVOIR
The full reservoir level (FRL) is fixed at El. 2015.00. The minimum draw
down level (MDDL) has been fixed at El. 1994.00m. The reservoir so
formed has a gross storage capacity of 89.95 ha-m at FRL and 10.00 ha-m
at MDDL. Available diurnal storage of 79.9500 ha-m is sufficient for
running the power station as a peaking station at full installed capacity for
3.00 hrs. The discharge availability in lean period(Nov. to Feb) in 90% dep.
year is 10.94 cumecs. The reservoir spreads over an area of about 7.50
hectares and is about 1.00 km long.
6.2.1.3 BARRAGE BAYS
6 barrage bays 6.00m wide each have been provided to pass the design
flood discharge i.e. 3050 cumecs. Total floor of 136m length has been
proposed comprising u/s floor, sloping glacis u/s & d/s (4:1) and d/s floor
of 50m including end still. A 4 m deep cut off extending up to El. 1981m
at u/s side of the floor and 5.00m deep cut off at the end of d/s floor
extending up to El. 1970m have been provided to protect the u/s and d/s
floor from scour/ piping action. Cement concrete blocks extending 10m
each beyond u/s and d/s floors have been provided. Protection to cement
concrete blocks have been provided with stone filled wire crates extending
VI - 3
10m beyond u/s & d/s floors. Consolidation grouting has not been proposed
in the river bed, keeping in view the fact that rock is not available upto
reasonable depth in the river bed.
6.2.1.4 ENERGY DISSIPATION
Dissipation of energy is proposed to be done by providing a horizontal
stilling basin depressed below the river bed level (El.1975m) with solid end
sill to facilitate formation of hydraulic jump. Layout & details of barrage
have been shown in drawing No. Bajoli-Holi-PR-4.
6.2.2 RIVER DIVERSION WORKS
The river diversion works have been designed for a discharge of 800
cumecs. The construction of diversion works i.e. half of barrage, intake
structure from inlet have been proposed to be taken up by making Ist Stage
coffer dam of length 300m allowing flow of water along the left bank of
river. After the completion of diversion barrage upto El. 1987m & Power
intake upto El. 1990m the Ist stage coffer dam shall be removed and
water shall be diverted on right bank of river through barrage constructed,
by making 2nd stage coffer dam. Thereafter, the construction of remaining
half of the barrage shall be completed. The construction of diversion works
has been proposed to be completed within three months period.
Construction of coffer dam is proposed to be modified as per site
conditions after each monsoon season.. The provision for construction of
coffer dam has been made accordingly, adding 50% quantum of work
being involved due to repetition of job after each season in the cost estimate
of the project. The provision of plain cement concrete of grade M-10 has
been made on the top and side slopes of coffer dam to prevent the seepage
of water towards working area.
VI - 4
6.2.2.1 INTAKE STRUCTURE
The intake structure comprising single intake with eight no. openings,has
been proposed on the right bank of river, to handle a discharge of 89.68
cumecs. A semi circular trash rack structure with reinforced concrete
columns has been proposed for intake. Crest elevation of intake is
proposed as 1990m. Stop logs has been proposed for controlling flow
through intake bays 8 nos.(5.50mx3m) each during repairs. A suitable
transition is provided to convert the rectangular opening into a 6.00m dia
circular approach tunnel. Approach tunnel is 200m long and shall lead the
water into two desanding basins. Details are shown in drawing No. Bajoli-
Holi- -PR-4.
6.2.3 DESANDING ARRANGEMENT
An underground desanding arrangement to exclude all silt particles down to
0.20mm has been proposed d/s of barrage axis on the right bank of river
Ravi. A lateral rock cover more than 3 time width has been ensured for
locating chamber No. 1. Rock cover of the order of twice the width of
excavated cavity of the chamber has been ensured in between the two
chambers. Stop logs will be provided at the inlet and outlet of all the
chambers to facilitate closing of any chamber for maintenance/repairs,
while the others will enable continuous operation of the power station.
Layout and details of desilting arrangement are given in drawing No.
Banjoli-Holi-PR-5.
6.2.4 HEAD RACE TUNNEL
6.2.4.1 GENERAL
The head race tunnel 5.00m dia, 14600m modified horse shoe type has
been proposed to carry a design discharge of 71.74cumecs from the
junction point of feeder tunnels of desilting chamber with HRT to the surge
shaft. The tunnel is located along right bank of river Ravi. Layout of the
tunnel has been fixed keeping in view the topography of the area and
VI - 5
location of construction adit from Ravi river for completing the tunnel
excavation work on schedule. Adequate rock cover has been ensured in
entire reach of the tunnel. The invert level of tunnel at RD-0 is at El.
1984.75 m and at outlet end at El. 1949.00m resulting in a slope of 1 in
409.
Six adits each 5m D-shaped at inlet, outlet and at intermediate locations
have been provided to facilitate construction of HRT from eight faces. The
inlet and outlet adits are so provided that they shall separate the
construction activity of the head race tunnel from that of desilting chambers
and surge shaft. The layout of the tunnel and other details are indicated in
Drawing. No. BAJOLI-HOLI-PR-6.
6.2.4.2 CROSS SECTION
Based on geological, hydraulic, structural and functional considerations,
modified horse shoe shaped cross section, 5.0m dia has been adopted. The
tunnel is proposed to be lined with concrete M:20.
6.2.5 SURGE SHAFT
6.2.5.1 GENERAL
The underground restricted orifice type surge shaft of 12m dia and 96.00m
height has been proposed at the outlet end of Head race tunnel at RD
14600. Top level of surge shaft is proposed at El. 2050.00m. One adit 5m
D-shaped, at the bottom at El. 1954.00m have been proposed. The bottom
adit will also be utilized to facilitate excavation of surge shaft and
horizontal portions of pressure shaft. After execution of the project this adit
will be plugged near junction of pressure shaft and rest of it will be used as
a drainage gallery. General layout and details of surge shaft are shown in
drawing No. Bajoli-Holi-PR-7.
VI - 6
6.2.5.2 HYDRAULIC PARAMETERS
Surge shaft area has been worked out by using Thomas’s criteria for
incipient stability with factor of safety as 1.6m conforming to IS:7396
(Part-I) 1979. Maximum upsurge and minimum down surge levels have
been computed by computer analysis as per above mentioned IS code.
Maximum upsurge level works out to be 2043.00m and minimum down
surge level as 1960.00m. For calculating maximum upsurge and minimum
down surge levels the friction co-efficient have been taken as 0.012 and
0.015 respectively.
6.2.5.2 CONCRETE LINING
It is proposed to provide reinforced concrete lining for surge shaft. Lateral
cover around surge shaft at all heights has been kept more than three times
the excavated diameter of the surge shaft. It is assumed that upsurge being
of very short duration will not cause any saturation in the surrounding rock
mass.
6.2.6 PRESSURE SHAFT
6.2.6.1 GENERAL
A 4.00m dia pressure shaft with centre line at El. 1951.50m will take off
from surge shaft for leading the water in to turbines. In the initial 20m
horizontal reach, a valve gallery has been proposed to accommodate
butterfly valve. The inclined length of main pressure shaft is 440m. Three
nos. branch pressure shaft of 2.30m dia 20m each in length, takes off from
the main pressure shaft to feed three units in the power house. The entire
length of the pressure shaft will be steel lined. The excavation of inclined
portion will be carried out from surge shaft bottom adit and from power
house cavity. The space between liner and excavated rock will be back
filled with M-20 conc. Adequate contact grouting will be done at contact
points of concrete with liner and rock. Consolidation grouting has also been
VI - 7
proposed in the reach, where the pressure shaft will pass through poor rock.
Details of pressure shaft are shown in Drawing No. BAJOLI HOLI-PR-7.
6.2.6.2 ECONOMIC DIAMETER
Economical dia of the pressure shaft has been worked out by cost
optimization studies for various diameters. Accordingly, a diameter of
4.00m has been adopted to carry the design discharge of 71.74cumecs with
velocity of flow as 5.74m/sec. The diameters of branches has been kept as
2.30m.
6.2.7 POWER HOUSE
6.2.7.1 GENERAL
The proposed underground power house is located about 2.0km. d/s of Holi
village on right bank of Ravi river. This site has been considered suitable
for underground power house. The tail race tunnel from power house will
discharge in to river Ravi. The erection bay and transformer hall floor
levels, are proposed at El. 1720m. The approach to power house and
transformer hall cavern is through 7m D-shaped main excess tunnel. The
machine hall and transformer hall are proposed in underground parallel
cavities at suitable spacing. The control room is proposed in power house
cavity while the SF6 switchgear is proposed in transformer hall cavity. A
cable cum ventilation gallery/tunnel is proposed, which will initially be
used for carrying out excavation and providing support system in the crown
portion of power house and transformers hall cavities. Vertical and lateral
cover each of ±200m approx. respectively has been provided in machine
cavity and transformer hall cavity. The safety of power house complex
from flooding, from tail water end during construction stage will be
adequately ensured.
VI - 8
6.2.7.2 TYPE
Reconnaissance surveys for location of underground or surface power
house are yet to be taken up. Surface power house has been ruled out due
to the reason that the entire area remains under snow cover for maximum
period in the year.
Keeping in view the above fact, an underground power house with
underground transformer hall has been proposed on right bank of Ravi
river. Also the GIS unnderground 220 KV Switchyard has been proposed
keeping in view the terrain and reliability of the system.
6.2.7.3 MACHINE HALL
The internal dimensions of power house cavity has been proposed as length
50m, width 17m and height 35m. For support system in crown portion of
cavity 6m long mechanically anchored , tensioned and grouted rock bolts
1.50m spacing, staggered has been proposed. 100mm thick shotcreting
reinforced with welded mesh has been proposed in crown portion and sides
of cavity. The spacing of rock bolts in sides has been kept at 2m c/c
staggered. The columns in unit bay and erection bay have been kept 1.60m
x 0.80m. For columns a nich in the side measuring 0.80mx0.80m has been
proposed which will be supported by grouted anchors 25mm dia at 1m
spacing. All rock bolts will be tensioned to 12 tonnes immediately after
installation and pull out tests will be carried out on 2% rock bolts.
The control bay is proposed on opposite side of erection bay in the end of
power house. Cavern for housing control room and various
auxiliaries/offices, 5 nos. floor have been proposed at El. 1716m, El.
1720m, El. 1724m, El. 1727.5m and El. 1730.5m respectively. The main
inlet valve is proposed to be housed in power house cavity just u/s of
turbine. EOT crane of 130/30 tonnes capacity has been proposed in erection
bay and unit bay to facilitate erection and repair of heavy equipment
including main inlet valves.
VI - 9
6.2.7.4 TRANSFORMER HALL
The size of transformer hall cavity has been proposed as 80m long, 16m
wide. The clear spacing between these two cavities has been kept at 30m.
In addition to main generator transformers, space for spare transformers
and station transformer has also been provided in the cavern. The
transformer hall cavern will be connected to erection bay by 5mx7m D-
shaped gallery for carriage of transformers at erection stage and for repairs.
NG rail track is proposed between transformer hall and erection bay for
transportation of transformers. The transformer hall will be connected by 3
nos. bus duct galleries 3m D-shaped.
The detail of power house has been shown in Drg. No. BAJOLI-HOLI-PR-
8&9.
6.2.8 AUXILLIARY SURGE SHAFT AND TAIL RACE TUNNEL
The outflow from the end of draft tube will be taken through 3 nos. separate
branch tail race tunnels. Vertical lift gates have been proposed in these
branch tail race tunnels to prevent entry of silt etc. into draft tube and for
facilitating repair in turbines. Downstream of this, all the branch tail race
tunnels will be joined to one main tail race tunnel 5m D-shaped, 450 m
long.
VI - 10
6.3 PRELIMINARY DRAWINGS
DRG. NO.BAJOLI-HOLI-PR-1 LOCATION & VICINITY MAP
DRG. NO.BAJOLI-HOLI-PR-2 CATCHMENT AREA PLAN
DRG. NO.BAJOLI-HOLI-PR-3 GENERAL LAYOUT PLAN
DRG. NO.BAJOLI-HOLI-PR-4 DIVERSION BARRAGE, INTAKE, PLAN &
SECTIONS
DRG. NO.BAJOLI-HOLI-PR-5 DESANDING BASIN PLAN & SECTIONS
DRG. NO.BAJOLI-HOLI-PR-6 HEAD RACE TUNNEL, PLAN & SECTION
DRG. NO.BAJOLI-HOLI-PR-7 SURGE SHAFT & PRESSURE SHAFT – PLAN &
SECTION
DRG. NO.BAJOLI-HOLI-PR-8 POWER HOUSE - PLAN
DRG. NO.BAJOLI-HOLI-PR-9 POWER HOUSE – SECTION
DRG. NO.BAJOLI-HOLI-PR-9(A) POWER HOUSE X–SECTION
DRG. NO.BAJOLI-HOLI-PR-10 SINGLE LINE DIAGRAM
DRG. NO.BAJOLI-HOLI-PR-11 CONSTRUCTION PROGRAMME
DRG. NO.BAJOLI-HOLI-PR-12 CONSTRUCTION FACILITIES
VI - 11
VI - 12
PARA DESCRIPTION PAGE
6.0 CONCEPTUAL LAYOUT OF PROJECT COMPONENTS VI-1
6.1 FINALIZATION OF CONCEPTUAL LAYOUT VI-1
6.2 PRELIMINARY DESIGN FEATURES VI-1
6.2.1 BARRAGE VI-1
6.2.1.1 GENERAL VI-1 TO VI-2
6.2.1.2 RESERVOIR VI-2
6.2.1.3 BARRAGE BAYS VI-2 TO VI-3
6.2.1.4 ENERGY DISSIPATION VI-3
6.2.2 RIVER DIVERSION WORKS VI-3
6.2.2.1 INTAKE STRUCTURE VI-4
6.2.3 DESANDING ARRANGEMENT VI-4
6.2.4 HEAD RACE TUNNEL VI-4
6.2.4.1 GENERAL VI-4 TO VI-5
6.2.4.2 CROSS SECTION VI-5
6.2.5 SURGE SHAFT VI-5
6.2.5.1 GENERAL VI-5
6.2.5.2 HYDRAULIC PARAMETERS VI-6
6.2.5.3 CONCRETE LINING VI- 6
6.2.6 PRESSURE SHAFT VI-6
6.2.6.1 GENERAL VI-6 TO VI-7
6.2.6.2 ECONOMIC DIAMETER VI- 7
6.2.7 POWER HOUSE VI-7
6.2.7.1 GENERAL VI-7
6.2.7.2. TYPE VI- 8
6.2.7.3 MACHINE HALL VI-8
6.2.7.4 TRANSFORMER HALL VI-9
VI - 13
6.2.8 AUXILIARY SURGE SHAFT AND TAIL RACE TUNNEL VI-9
6.3 PRELIMINARY DRAWINGS VI-10
CHAPTER – VI
CONCEPTUAL LAYOUT
AND PLANNING
6.0 CONCEPTUAL LAYOUT OF PROJECT COMPONENTS
6.1 FINALIZATION OF CONCEPTUAL LAYOUT
The proposed Civil Engineering Structures have been planned and designed
to divert and conduct 71.74 lacs of water, from river Ravi for generating
180MW of power in an underground power house by utilizing a gross head
of 308.00 m. The main works of the project comprise a diversion barrage,
intake, underground desanding basins for removing all particles down to
0.20mm size, 14600m long head race tunnel, a restricted orifice type surge
shaft and an underground power house to accommodate 3 vertical axis,
Francis turbines driven generating units each of 60 MW. After diversion,
all the civil engineering components have been kept underground keeping
in view the topography of the area. A brief geological site specific
feasibility note titled “Geo-technical appraisal” founded on preliminary site
inspection about each component is appended as Para 4.5 in chapter-IV
titled “Geo-technical Aspects”.
6.2 PRELIMINARY DESIGN FEATURES
6.2.1 BARRAGE
6.2.1.1 GENERAL
The slope of river at the diversion site u/s of Bajoli village is of the order of
1 in 55. Peak annual flood of river Ravi at diversion site has been adopted
as 3050 cumecs for design of spillways/barrage bays. Barrage 100m long
including abutments with crest level of barrage bays at El. 1987m & non
over flow section has been proposed to pass the estimated design flood at
FRL El. 2015.00m. The proposed barrage comprises 6 bays of 6.00m each
with 3.00m thick piers and is capable of passing the estimated design flood
even when one bay is considered inoperative during period of high floods.
The max. pond level/ FRL (El. 2015.00m) attained during winter months
shall also cater to peaking requirement . During high flood max. water level
to be attained has been proposed as 2016.00m. Radial gates in the barrage
bays shall be provided from top of crest El. 1987m to the bottom of RCC
breast wall El. 1995.00m spanning between the piers. The breast wall is
supported on the piers and is provided between El. 1995.00m and El.
2018.00m.
6.2.1.2 RESERVOIR
The full reservoir level (FRL) is fixed at El. 2015.00. The minimum draw
down level (MDDL) has been fixed at El. 1994.00m. The reservoir so
formed has a gross storage capacity of 36.00 ha-m at FRL and 7.60 ha-m at
MDDL. Available diurnal storage of 22.72 ha-m ( 85.00-20% reserved for
silt deposits) is sufficient for running the power station as a peaking station
at full installed capacity for 3.00 hrs. The discharge availability in lean
period(Nov. to Feb) in 90% dep. year is 10.94 cumecs. The reservoir
spreads over an area of about 12.00 hectares and is about 1.00 km long.
6.2.1.3 BARRAGE BAYS
6 barrage bays 6.00m wide each have been provided to pass the design
flood discharge i.e. 3050 cumecs. Total floor of 136m length has been
proposed comprising u/s floor, sloping glacis u/s & d/s (4:1) and d/s floor
of 50m including end still. A 4 m deep cut off extending up to El. 1981m
at u/s side of the floor and 5.00m deep cut off at the end of d/s floor
extending up to El. 1970m have been provided to protect the u/s and d/s
floor from scour/ piping action. Cement concrete blocks extending 10m
each beyond u/s and d/s floors have been provided. Protection to cement
concrete blocks have been provided with stone filled wire crates extending
10m beyond u/s & d/s floors. Consolidation grouting has not been proposed
in the river bed, keeping in view the fact that rock is not available upto
reasonable depth in the river bed.
6.2.1.4 ENERGY DISSIPATION
Dissipation of energy is proposed to be done by providing a horizontal
stilling basin depressed below the river bed level (El.1975m) with solid end
sill to facilitate formation of hydraulic jump. Layout & details of barrage
have been shown in drawing No. Bajoli-Holi-PR-4.
6.2.2 RIVER DIVERSION WORKS
The river diversion works have been designed for a discharge of 800
cumecs. The construction of diversion works i.e. half of barrage, intake
structure from inlet have been proposed to be taken up by making Ist Stage
coffer dam of length 300m allowing flow of water along the left bank of
river. After the completion of diversion barrage upto El. 1987m & Power
intake upto El. 1990m the Ist stage coffer dam shall be removed and
water shall be diverted on right bank of river through barrage constructed,
by making 2nd stage coffer dam. Thereafter, the construction of remaining
half of the barrage shall be completed. The construction of diversion works
has been proposed to be completed within three months period.
Construction of coffer dam is proposed to be modified as per site
conditions after each monsoon season.. The provision for construction of
coffer dam has been made accordingly, adding 50% quantum of work
being involved due to repetition of job after each season in the cost estimate
of the project. The provision of plain cement concrete of grade M-10 has
been made on the top and side slopes of coffer dam to prevent the seepage
of water towards working area.
6.2.2.1 INTAKE STRUCTURE
The intake structure comprising single intake with eight no. openings,has
been proposed on the right bank of river, to handle a discharge of 89.68
cumecs. A semi circular trash rack structure with reinforced concrete
columns has been proposed for intake. Crest elevation of intake is
proposed as 1990m. Stop logs has been proposed for controlling flow
through intake bays 8 nos.(5.50mx3m) each during repairs. A suitable
transition is provided to convert the rectangular opening into a 6.00m dia
circular approach tunnel. Approach tunnel is 200m long and shall lead the
water into two desanding basins. Details are shown in drawing No. Bajoli-
Holi-PR-4.
6.2.3 DESANDING ARRANGEMENT
An underground desanding arrangement to exclude all silt particles down to
0.20mm has been proposed d/s of barrage axis on the right bank of river
Ravi. A lateral rock cover more than 3 time width has been ensured for
locating chamber No. 1. Rock cover of the order of twice the width of
excavated cavity of the chamber has been ensured in between the two
chambers. Stop logs will be provided at the inlet and outlet of all the
chambers to facilitate closing of any chamber for maintenance/repairs,
while the others will enable continuous operation of the power station.
Layout and details of desilting arrangement are given in drawing No.
Banjoli-Holi-PR-5.
6.2.4 HEAD RACE TUNNEL
6.2.4.1 GENERAL
The head race tunnel 5.00m dia, 14600m modified horse shoe type has
been proposed to carry a design discharge of 71.74cumecs from the
junction point of feeder tunnels of desilting chamber with HRT to the surge
shaft. The tunnel is located along right bank of river Ravi. Layout of the
tunnel has been fixed keeping in view the topography of the area and
location of construction adit from Ravi river for completing the tunnel
excavation work on schedule. Adequate rock cover has been ensured in
entire reach of the tunnel. The invert level of tunnel at RD-0 is at El.
1984.73 m and at outlet end at El. 1949.00m resulting in a slope of 1 in
409.
Six adits each 5m D-shaped at inlet, outlet and at intermediate locations
have been provided to facilitate construction of HRT from eight faces. The
inlet and outlet adits are so provided that they shall separate the
construction activity of the head race tunnel from that of desilting chambers
and surge shaft. The layout of the tunnel and other details are indicated in
Drawing. No. BAJOLI-HOLI-PR-6.
6.2.4.2 CROSS SECTION
Based on geological, hydraulic, structural and functional considerations,
modified horse shoe shaped cross section, 5.0m dia has been adopted. The
tunnel is proposed to be lined with concrete M:20.
6.2.5 SURGE SHAFT
6.2.5.1 GENERAL
The underground restricted orifice type surge shaft of 12m dia and 96.00m
height has been proposed at the outlet end of Head race tunnel at RD
14600. Top level of surge shaft is proposed at El. 2050.00m. One adit 5m
D-shaped, at the bottom at El. 1954.00m have been proposed. The bottom
adit will also be utilized to facilitate excavation of surge shaft and
horizontal portions of pressure shaft. After execution of the project this adit
will be plugged near junction of pressure shaft and rest of it will be used as
a drainage gallery. General layout and details of surge shaft are shown in
drawing No. Bajoli-Holi-PR-7.
6.2.5.2 HYDRAULIC PARAMETERS
Surge shaft area has been worked out by using Thomas’s criteria for
incipient stability with factor of safety as 1.6m conforming to IS:7396
(Part-I) 1979. Maximum upsurge and minimum down surge levels have
been computed by computer analysis as per above mentioned IS code.
Maximum upsurge level works out to be 2043.00m and minimum down
surge level as 1960.00m. For calculating maximum upsurge and minimum
down surge levels the friction co-efficient have been taken as 0.012 and
0.015 respectively.
6.2.5.2 CONCRETE LINING
It is proposed to provide reinforced concrete lining for surge shaft. Lateral
cover around surge shaft at all heights has been kept more than three times
the excavated diameter of the surge shaft. It is assumed that upsurge being
of very short duration will not cause any saturation in the surrounding rock
mass.
6.2.6 PRESSURE SHAFT
6.2.6.1 GENERAL
A 4.00m dia pressure shaft with centre line at El. 1951.50m will take off
from surge shaft for leading the water in to turbines. In the initial 20m
horizontal reach, a valve gallery has been proposed to accommodate
butterfly valve.The inclined length of main pressure shaft is 440m. Three
nos. branch pressure shaft of 2.30m dia 20m each in length, takes off from
the main pressure shaft to feed three units in the power house. The entire
length of the pressure shaft will be steel lined. The excavation of inclined
portion will be carried out from surge shaft bottom adit and from power
house cavity. The space between liner and excavated rock will be back
filled with M-20 conc. Adequate contact grouting will be done at contact
points of concrete with liner and rock. Consolidation grouting has also been
proposed in the reach, where the pressure shaft will pass through poor rock.
Details of pressure shaft are shown in Drawing No. BAJOLI HOLI-PR-7.
6.2.6.2 ECONOMIC DIAMETER
Economical dia of the pressure shaft has been worked out by cost
optimization studies for various diameters. Accordingly, a diameter of
4.00m has been adopted to carry the design discharge of 71.74cumecs with
velocity of flow as 5.74m/sec. The diameters of branches has been kept as
2.30m.
6.2.7 POWER HOUSE
6.2.7.1 GENERAL
The proposed underground power house is located about 2.0km. d/s of Holi
village on right bank of Ravi river. This site has been considered suitable
for underground power house. The tail race tunnel from power house will
discharge in to river Ravi. The erection bay and transformer hall floor
levels, are proposed at El. 1720m. The approach to power house and
transformer hall cavern is through 7m D-shaped main excess tunnel. The
machine hall and transformer hall are proposed in underground parallel
cavities at suitable spacing. The control room is proposed in power house
cavity while the SF6 switchgear is proposed in transformer hall cavity. A
cable cum ventilation gallery/tunnel is proposed, which will initially be
used for carrying out excavation and providing support system in the crown
portion of power house and transformers hall cavities. Vertical and lateral
cover each of ±200m approx. respectively has been provided in machine
cavity and transformer hall cavity. The safety of power house complex
from flooding, from tail water end during construction stage will be
adequately ensured.
6.2.7.2 TYPE
Reconnaissance surveys for location of underground or surface power
house are yet to be taken up. Surface power house has been ruled out due
to the reason that the entire area remains under snow cover for maximum
period in the year.
Keeping in view the above fact, an underground power house with
underground transformer hall has been proposed on right bank of Ravi
river. Also the GIS underground 220 KV Switchyard has been proposed
keeping in view the terrain and reliability of the system.
6.2.7.3 MACHINE HALL
The internal dimensions of power house cavity has been proposed as length
50m, width 17m and height 35m. For support system in crown portion of
cavity 6m long mechanically anchored , tensioned and grouted rock bolts
1.50m spacing, staggered has been proposed. 100mm thick shotcreting
reinforced with welded mesh has been proposed in crown portion and sides
of cavity. The spacing of rock bolts in sides has been kept at 2m c/c
staggered. The columns in unit bay and erection bay have been kept 1.60m
x 0.80m. For columns a nich in the side measuring 0.80mx0.80m has been
proposed which will be supported by grouted anchors 25mm dia at 1m
spacing. All rock bolts will be tensioned to 12 tonnes immediately after
installation and pull out tests will be carried out on 2% rock bolts.
The control bay is proposed on opposite side of erection bay in the end of
power house. Cavern for housing control room and various
auxiliaries/offices, 5 nos. floor have been proposed at El. 1716m, El.
1720m, El. 1724m, El. 1727.5m and El. 1730.5m respectively. The main
inlet valve is proposed to be housed in power house cavity just u/s of
turbine. EOT crane of 130/30 tonnes capacity has been proposed in erection
bay and unit bay to facilitate erection and repair of heavy equipment
including main inlet valves.
6.2.7.4 TRANSFORMER HALL
The size of transformer hall cavity has been proposed as 80m long, 16m
wide. The clear spacing between these two cavities has been kept at 30m.
In addition to main generator transformers, space for spare transformers
and station transformer has also been provided in the cavern. The
transformer hall cavern will be connected to erection bay by 5mx7m D-
shaped gallery for carriage of transformers at erection stage and for repairs.
NG rail track is proposed between transformer hall and erection bay for
transportation of transformers. The transformer hall will be connected by 3
nos. bus duct galleries 3m D-shaped.
The detail of power house has been shown in Drg. No. BAJOLI-HOLI-PR-
8 & 9.
6.2.8 AUXILLIARY SURGE SHAFT AND TAIL RACE TUNNEL
The outflow from the end of draft tube will be taken through 3 nos. separate
branch tail race tunnels. Vertical lift gates have been proposed in these
branch tail race tunnels to prevent entry of silt etc. into draft tube and for
facilitating repair in turbines. Downstream of this, all the branch tail race
tunnels will be joined to one main tail race tunnel 5m D-shaped, 450 m
long.
6.3 PRELIMINARY DRAWINGS
DRG. NO.BAJOLI-HOLI-PR-1 LOCATION & VICINITY MAP
DRG. NO.BAJOLI-HOLI-PR-2 CATCHMENT AREA PLAN
DRG. NO.BAJOLI-HOLI-PR-3 GENERAL LAYOUT PLAN
DRG. NO.BAJOLI-HOLI-PR-4 DIVERSION BARRAGE, INTAKE, PLAN &
SECTIONS
DRG. NO.BAJOLI-HOLI-PR-5 DESANDING BASIN PLAN & SECTIONS
DRG. NO.BAJOLI-HOLI-PR-6 HEAD RACE TUNNEL, PLAN & SECTION
DRG. NO.BAJOLI-HOLI-PR-7 SURGE SHAFT & PRESSURE SHAFT – PLAN &
SECTION
DRG. NO.BAJOLI-HOLI-PR-8 POWER HOUSE - PLAN
DRG. NO.BAJOLI-HOLI-PR-9 POWER HOUSE – SECTION
DRG. NO.BAJOLI-HOLI-PR-10 SINGLE LINE DIAGRAM
DRG. NO.BAJOLI-HOLI-PR-11 CONSTRUCTION PROGRAMME
PARA DESCRIPTION PAGE
6.0 CONCEPTUAL LAYOUT OF PROJECT COMPONENTS VI-1
6.1 FINALIZATION OF CONCEPTUAL LAYOUT VI-1
6.2 PRELIMINARY DESIGN FEATURES VI-1
6.2.1 BARRAGE VI-1
6.2.1.1 GENERAL VI-1 TO VI-2
6.2.1.2 RESERVOIR VI-2
6.2.1.3 BARRAGE BAYS VI-2 TO VI-3
6.2.1.4 ENERGY DISSIPATION VI-3
6.2.2 RIVER DIVERSION WORKS VI-3
6.2.2.1 INTAKE STRUCTURE VI-4
6.2.3 DESANDING ARRANGEMENT VI-4
6.2.4 HEAD RACE TUNNEL VI-4 TO VI-5
6.2.4.2 CROSS SECTION VI-5
6.2.5 SURGE SHAFT VI-5
6.2.5.1 GENERAL VI-5
6.2.5.2 HYDRAULIC PARAMETERS VI-6
6.2.5.3 CONCRETE LINING VI- 6
6.2.6 PRESSURE SHAFT VI-6
6.2.6.1 GENERAL VI-6 TO VI-7
6.2.6.2 ECONOMIC DIAMETER VI- 7
6.2.7 POWER HOUSE VI-7
6.2.7.1 GENERAL VI-7
6.2.7.2. TYPE VI- 8
6.2.7.3 MACHINE HALL VI-8
6.2.7.4 TRANSFORMER HALL VI-9
6.2.8 AUXILIARY SURGE SHAFT AND TAIL RACE TUNNEL VI-9
6.3 PRELIMINARY DRAWINGS VI-10
6.4 DESIGN COMPUTATIONS A. Diversion Barrage ( REF. DRG. NO. BAJOLI - HOLI-PR-4)
i) Design Parameters Design flood discharge = 3050 cum/sec. Average bed level of the river = ± 1985m
Safe exit gradient of Nallah material (assumed) = 1 in 4 The water bays of the barrage has been so proposed that design flood discharge i.e. 3050 cum/sec passes through all the bays of barrage.
However, stilling basin has been designed corresponding to max. observed discharge in Chenab river i.e. 379.46 cumecs Say 1000 cumecs.
Hence design flood discharge for stilling basin = 1000 cumecs ii) Fixation of crest level and water bay
Average bed level of river = ± 1985m The crest level of barrage bays has been kept 2m higher than the average bed level at El. ±1985m . Six No. bays each 5.00m wide with 3m thick pier has been provided. The total water bay of overflow portion works out to be 54.00m[(6x6)+(3.00x6)] . Two meter wide fish ladder Originating from reservoir, left bank at M.D.D.L. El. ± 1994m joining river bed d/s has been provided.
iii) Storage capacity
The live storage available in barrage reservoir between M.D.D.L. El. 1994m and F.R.L. El. 2015m is 85 Hect. m. This storage capacity will run the power station at full installed capacity for 3 hrs. a day. CHECKING OF LEVELS AND CALCULATIONS FOR SIZE OF GATES Design discharge for power generation = 71.74 cumecs Total discharge i/c flushing discharge @ 20% = 71.74/(1-0.20) =71.74/80 = 89.67 cumecs Fixing crest level of intake = ± 1990m M.D.D.L. = ± 1994m F.R.L. = ± 2015 m
Providing one no. power intake, having 8 no. bays each of size
= 5.50 m(b)x3m(h) a) F.R.L. Condition Intake crest behaves as a rectangular large orifice
H1 = 25.00m H2 = 21m
Discharge Passed Q1 = 2/3xCdxLx√ 2g (H1
3/2-H2 3/2 ) = 2/3x0.61x44√2x9.81 (253/2 –213/2 )
= 2279 cumecs >89.67 cumecs Hence O.K.
b) M.D.D.L CONDITION
H1 = 4.00m H2 = 0.50m Q = 2/3xCdxLx√2g (H1
3/2-H23/2)
= 2/3x0.61x44x√2x9.81 (43/2-0.503/2) =605.00 cumecs > 89.67 cumecs Hence O.K. CHECK FOR VELOCITY THROUGH TRASH RACK Aligning trash rack at 75° Design discharge through intake/trash rack = 89.67 cumecs F.R.L. Condition Length of trash rack = xm
25/x = Sin75° x = 25/Sin75° = 25.88m Area = 25.88x44 = 1139 Sqm.
Less 25% area for trash rack bars = 1139-1139x0.25= 854 Sqm. Considering 50% clogging of trash rack bars Net area available during floods = 854/2 = 427 Sqm. Velocity through trash rack = 89.67/427 = 0.21m/sec.
M.D.D.L. condition
Length of trash rack = 4.0/x = Sin75° x = 4.00/Sin75 x = 4.14 m
Area available = 4.14x44 = 182.2 Sqm. Less 25% area of rack bars Net area = 182.20-182.20x0.25 =136.65 Sqm. Considering 50% area of trash rack bars Net area = 136.65-136.65x0.50 = 68.32 Sqm. Velocity through trash rack = 89.67/68.32 = 1.31m/sec. Hence size of intake provided and levels fixed are O.K.
Gated barrage is to be provided
Parameters will be as under; R.B.L. = 1985m Crest level = 1987m of barrage bays (fixed) M.D.D.L. = 1994m F.R.L. = 2015m M.R.L. = 2016m Top of barrage = 2018m Height of structure = 3424-3405 =19m Design flood = 3050 cum/sec. Size of gate = 6mx8m No. of gate = 6 No. Storage available between El. MDDL 1994m and F.R.L. 2015m It is assumed that Live storage= 85.00 Hac. m Less 20% for sedimentation Net = 85-17.00 = 68 hect .m. Time in hr = 68x104/(71.74-12.50)x3600 = 3.19 hours For Base Load Station 90% available discharge = 12.50 cumecs Design discharge = 71.74 cumecs Power = 9.81x71.74x278x0.92/1000 = 180 MW
Hydraulic design of free flowing/ungated structure Design discharge for power generation = 71.74 cumecs Modified discharge including 20% flushing Discharge in desanding basin = 71.74/(1-0.20)= 89.67 cum If it is the head over intake crest to pass 89.67 cumecs discharge Q = CLH3/2 89.67 = 1.70x44xH3/2 H3/2 = 89.687/1.70x44 H = 1.20m R.B.L. = 1985m Crest level of over flow bay = 1987m Crest level of intake crest = 1990m
Head over crest to pass 89.67 cumecs discharge = 1.20m Water level = 1990+1.20 = 1991.20m Hence if ungated barrage is to be provided the level of Ungated crest will have to be kept as 1991.20m Height of structure =1991.20-1985 = 6.20m Live storage (Between El. 1990& 1991.20m)= = 6.00 hacm.(Assumed) Time in hours = 6.00x104/(71.74-12.50)x3600 = 0.28 hrs. If height of structure is kept upto El. 1995m Height of structure = 1995-1985 = 10m Live storage (Between El. 1990 & El. 2000) = 30.00hacm.(Assumed) Time in hrs = 30.00x104/(71.74-12.5)x3600 = 1.41 hrs. Time to filling up of this storage = 8 months.
CALCULATIONS FOR SIZE OF GATES IN BARRAGE BAYS
As per I.S. recommendations, 10% gates are considered to be inoperative during floods(with min. one gate)
R.B.L. = 1985m
Crest level = 1987m M.D.D.L. = 1994m F.R.L. = 2015.00m M.R.L. = 2016.00m No. of barrage bays= 6 nos.
Width of each barrage bay =6m Providing radial gate from El. 1987m to El. 1995.00m & breast wall Thereafter upto El. 2018m Size of gate = 6mx8m Discharge through breast wall spillway is estimated by the equation Q = Cb.L.D. [2g(He+Vo2/2g]0.50 Where L = Total width of water bays available = 6x6 =36m D = Height of opening = 8.00m He = Head from C/L of spillway He =[(1995.00-1987)/2]+[2015-1994] = 4.00+21 =25.00m Vo = Vel. of approach of flood water = 3050/100x 25 = 0.68m/sec. Vel. head = Vo2/2g = 0.682/2x9.81 = 0.023 For calculating discharge co-efficient Head H = 2015-1987 = 28.00m Considering that design head may be exceeded by 25% H/Hd = 1.25 Design head Hd = H/1.25 = 28/1.25 = 22.40m Choosing Hd = 22.50m H/Hd = 1.4/11.50 = 1.244 Corresponding value of Cb = 0.811 When all the bays are open Discharge passed =Q = Cb.L.D. [2g(He+Vo2/2g) ] 0.50
Q = 0.809x36x8.00 [2x9.81(25+0.023) ]0.50
= 5169 cumecs When one barrage bay is inoperative Q = Cb.L.D. [2g(He+Vo2/2g) ] 0.50
= 0.809x30x8.00 [2x9.81(25+.023) ]0.50 = 4307 cumecs which is more than 3050 cumecs Hence O. K. HYDRAULIC DESIGN OF STILLING BASIN Fixation of pre-jump velocity and depth of flow The theoretical velocity at the start of the jump is calculated by the following relation: VT = √ 2g (H-0.50 Hd) Where VT = Theoretical velocity in m/sec. H = Difference in u/s reservoir El. and stilling basin invert in meters H = 2016-1975 = 41m H = Head over crest of barrage bays in meters
= 2016-1987 = 28m g = Acceleration due to gravity in m/sec = 9.81 m/sec. VT = √ 2x9.81 (41-0.50x28.00) VT = 23.02m/sec. Due to surface friction, the actual velocity is less than VT Considering VA= VT = 23.02m/sec
Discharge equation Q = A1xV1
Where
1000 = A1x23.02 VA=V1 23.02m/sec. A1 = 1000/23.02 = 43.44 Sqm. Q = Design flood discharge of Stilling basin =1000 cum L.D1 = 43.44 45.00xD1 = 43.44 ∴ D1 = 43.44/45.00 =0.965m
Froude No. (F) = V1/√ gd1 = 23.02/√9.81x0.965m
= 7.48 For Froude no. 7.48>4.50, U.S.B.R. type-III stilling basin is recommended. D2 = Depth Conjugate to D1 D2 = D1/2+√2q2/D1g +D1
2/4 Here q = 1000/45.00 =22.22 cum/sec D2 = -0.965/2+√2x22.222/0.965x9.81+0.965^2/4 = -0.48+10.08 = 9.60 m Length of basin = 5xD2 = 5*9.60 = 48.40 Say 50m
The floor of the basin is set at such a level at to provide 5% more water depth than Y2
Hence depth of basin = 9.60x1.05 = 10.08 m
Cistern level = 1985-10 = 1975 m Hence provided cistern level = 1975m is O.K.
SIZE OF APPROACH TUNNEL
Design discharge Q = 71.74/0.80 = 89.67 cum/sec. No. of main tunnels = 1 no. Discharge through each tunnel = 89.67 cum/sec. Vel. in the tunnel = 3.30m/sec Dia of tunnel = √(93.75/3.30)/4/Π = 5.88m
After bifurcation
Q through each tunnel = 44.84 V = 3.30 cum/sec.
Dia of each tunnel √ 44.84x4/3.30xΠ = 4.159 m say 4.25 m After Desilting
Total design discharge, Q = 71.74 cum/sec.
No. of tunnels = 2 nos.
Discharge through each tunnel = 71.74/2 =35.87 cum/sec Dia = 4.25m V = 35.87/Π/4(4.25)² = 2.52m/sec.
DESIGN OF APPROACH TUNNEL & INTAKE STRUCTURE A. APPROACH TUNNELS ( Ref. Drawing No. Bajoli-Holi-PR-6)
Design discharge to be drawn i/c flushing discharge = 89.67 cum/sec.
No. of tunnels = 1 nos.
Discharge through each tunnel = 89.67 cum/sec.
Provide size of tunnel = 6m, circular concrete lined
Area of each tunnel = Π/4(d²) = Π/4(6)² = 28.27 Sqm.
Vel. through each tunnel = 89.67/28.27 = 3.17 m/sec. Length of tunnel = 300m B. INTAKE STRUCTURE
Considering bell mouth intake with bottom flat
Width of opening = 1.42857 D D = Size of conduit i.e. tunnel = 1.42857x6.00 = 8.57m
Height of opening h = h1+h2 h1 [(1.21 tan2φ +0.0847)1/2+1/2 cosφ -1.1 tanφ )]D Where φ is the angle of inclination with Horizontal = 0° h1 = [(1.21 tan20+0.0847)1/2+(1/2cos 0-1.1 tan0 )] xD = [(0+0.0847)1/2 + ½]x6 = (0.291+0.50) 6 = 4.75m h2 = [0.791/ +0.077 tan0]xD = (0.791+0) x 6 = 4.75m
h = h1+h2 =4.75+4.75 = 9.50m Provide clear opening for intake = 8.60x9.50m
The opening is rectangular and depress it to circular from starting of intake face to a distance of 1.1 D = 1.1x6 = 6.60m
Here
a = 6.60m b = 3.50m Hence size of bell mouth entrance 8.60m(b)x9.50m(d) from 6m circular section Min. water cushion provided above the opening of intake = 0.3 he = 0.3x9.50 = 2.85m El. at top of intake = 1994-2.85 = 1990.15m C/L of intake = 1990-4.75/2 = 1987.625m C/L of approach tunnel = 1987.625 m Hence invert level of approach tunnel at RD 0 =1987.625-6/2 =1984.63m And C/L of approach tunnel at inlet = 1984.63m
Invert level as invert = 1984.63m At inlet of desanding basin Invert level = 1984.23m Overt level = 1984.23+4.25m = 1988.48m
HYDRAULIC DESIGN OF DESANDING BASIN (Underground ) (Ref. Drawing No. Chhatru-FR-5 sheet 2 of 2) Design criteria = All particles down to 0.20mm shall be removed Parameters Design discharge for power generation = 71.74 cumecs Design discharge i/c 20% for deflushing in desanding basin=71.74/0.80 = 89.67 cumecs
HYDRAULIC DESIGN Particle size to be removed = 0.020mm and above Permissible flow through vel. as per camp’s formula
V = 44√d for 1mm>d>0.10mm V = 44√0.020 = 19.67 cm/sec
Provide v = 19.50 cm/sec Effective area of flow = 93.75/0.1950 = 459.90 Sqm. Provide 2 No. chambers in the desanding basin Width of each basin = 13.00m Total width = 13x2 = 26m Effective area of flow of each chamber = 459.90/2 = 229.75 Sqm. CHECK FOR CROSS SECTIONAL AREA Arch Portion r = (C²+4h²)/8h = (13²+4x3.50²)/8x3.50 = 7.78m Sin α/2 = C/2/2 = 6.50/7.78 = 0.835 α/2 = 56.66° α = 113.33° Length of arch =Π/180xαxr L =Π/180x113.33x7.78
= 15.38m A Area of Arch Portion A1 = ½[r.L-C(r-h)] A1 = ½[(7.78x15.38)-13(7.78-3.50)] = ½(119.65-55.64) = 32 Sqm. A2 = Area of rectangular Portion = 13x16.10 = 208 Sqm. Total area = A1 + A2 =32+208 =240 Sqm.>2229.75 Sqm.
Hence O.K. 0.20mx0.20m openings are proposed to be provided at the bottom of each pit 10m c/c to carry the silt to gallery 1.50x1.80m rectangular shaped, from where silted water will be flushed back to Beas river. Settling vel. = 2.35cm/sec corresponding to 0.20mm particle size Vel. correction W1 = 0.132xv/√h = 0.132x0.195/√19.50 W1 = 0.00581 Corrected settling vel. = W-W1 = 0.02350-0.00581 = 0.017685 Length of desanding basin L = hxV/W-W1 = 19.60x0.195/0.017685 L = 216.11m Provide L = 380m Hence size of each chamber = 380m(L)x13m(b)x19.60m(h) No. of chambers = 2 nos. CHECK FOR THE SIZE Settling time t is given by t = h/W-W1 = 19.60/0.017685 = 1108.28 sec. Water conveyed during this period Qxt = Discharge per chamber x settling time = (93.75/2) x 1108.28 = 51950.80 cum Capacity of one chamber = 241.30x380= 91935 cum>51950.80 cum Hence O.K.
Removal efficiency of particle size of 0.20mm ηt = 1-(e) –WxL/vxh = 1-e –2.35x380/19.50x19.60 = 1-0.0960 = 90.40% Design of transitions Inlet transition length = B-b/2tan 12.5º = 13-4.25/2tan 12.5º = 19.73m Say 20.00m Outlet transition length = 13-4.25/2tan 12.5º = 19.73m Say 20.00m HEAD RACE TUNNEL(REF. DRAWING NO. CHHATRU-FR-6) Parameters Design discharge = 75 cumecs Shape of the tunnel (adopted) = Modified horse shoe shaped Length of head race tunnel = 6500m M.D.D.L. = 3413.50m Min. down surge level (as per computer analysis) = 3396.96m Co-efficient of friction = 0.014 HYDRAULIC DESIGN Calculation for economic diameter
The most economical dia of tunnel would be such as to result in a minimum total value of the sum of the following.
a) Recurring annual expenditure According to Manning formula’s V = 1/nx R2/3 S1/2
Where V = Average vel. X = Rugosity co-efficient = 0.014 R = Hydraulic mean radius = 0.506287 r
D = Diameter S = Slope Now V = 1/n R2/3 S1/2= 1/n (D/4)2/3 S1/2
S = 6.40 V²n²/D1.33 -(i) In this equation S gives value of head loss in meter or hydraulic gradient If η is the overall efficiency of generation Then Power lost Pe = 9./80xQxSxη KW -(ii) Where Q = VxΠ/4 (D²) Or V = 1.275Q/D² -(iii) From equation (i) & (iii) we got S = 6.40n²/D5.33x[1.275Q/D²]² - (iv) Substituting the value of S in (ii) we get revenue lost per year Pe = 9.80Q [6.40n²/D5.33 (1.275Q/D²)²]x η KW (A) Pe = 101.96 Q3/D1.33xn²xη KW Revenue lost per year Re = Pex24x365x C0 (B) From equation A&B Re = [ 101.96 Q3/D5.33xn²xη]x24x365xC0 Re = 8.95x105
x Qª/D5.33xn2xηxC0 Re = 8.95x105
x Qª/D5.33xηxn2xC0 C0 = Selling rate of power per unit = Rs. 2.50 η = Overall efficiency = 0.92 Q = Equivalent discharge =Design discharge x Load factor
= 75x0.50 = 37.50 cum/sec. ∴ Re = [8.95x105x(37.50)3 x0.92x(0.014)²x2.50] /D5.33 Re = 2.127x107/D5.33
Annual expenditure/Cost per year (Ae) Assuming lining thickness = D/16 (Including OB) Qty. of excavation per meter length = Π/4 (D+2xD/16)² = Π/4x81/64 D² = 0.994 D² Rate of Excavation Good rock = 903x0.60 = Rs. 541.80 Moderately jointed rock = 1499x0.20 = Rs. 299.80 Poor rock = 1906x0.20 = Rs. 381.20 Total = Rs. 541.80+299.80+381.20 = Rs. 1222.80 Rate of over break per cum = 2.3x1222.80 = Rs. 815.20/ cum
Cost of excavation including over break = 1222.80+81.52 (10% of Rs.815.20) = Rs. 1304.32 Rate of excavation per cum = Rs. 1304.32 Say Rs. 1305.00 Rate of lining M:20 = Rs. 3177 per cum Qty. of steel for ribs @ 18 kg.per cum = 0.018x56037 = Rs. 1008.66 Say Rs. 1009.00 Total cost of lining = 3177+1009 = Rs. 4186.00 Area of lining = Π(D+D/16)D/16 = 0.2086 D² Cost of excavation = 0.994 D²x1305 = 1297.17 D² Cost of lining = 0.2086D²x4186 = 873.19D² Total cost = 1297.17 D²+873.19 D²= 2170.36D² Total cost including over head charges @ 15% on total cost = 2495.91D² Ae = Annual expenditure @ 15.50% of above cost =
= 2495.91D²x0.155 = 386.87 D2
Now T Re+Ae T = 2.13x107/D5.33+386.87D² For mix. value DT/Dd = 0 T = 2.13x107/D5.33+386.87 D² =2.13x107xD-5.33+386.87D² For min. value DT/Dd = -5.33 D-6.33x2.13x107+2D(386.87) = 0 -1.135x108 D-6.33 = -773.74D D 7.33 = 1.135x108/773.74 = 146690.10 D = 5.07m Say 5.10m Hence dia of H.R.T. (fixed) = 5.10m Vel. in the H.R.T. = 75/20.63 = 3.63m/sec. D = 5.10m R = 5.00/2 = 2.55m r = 0.987580 R =0.987580x2.55 = 2.52m R = RARIUS OF HYDRAULICALLY EQUIVALENT CIRCLE AREA OF SECTION = 3.253 572 r2 = 20.63 Sqm. PERIMETRE OF SECTION = 6.426 334r = 16.19m
HYDRAULIC RADIUS = 0.506 287 r = 1.27m A = 0.780 776 r = 1.97m B = 1.561 553 r = 3.93m θ = 31º-22’-01” SURGE SHAFT (REF. DRAWING NO. CHHATRU-FR-6)
Hydraulic Design
Design discharge = 75 cumecs Size & shape of head race tunnel = 5.10m, Modified horse shoe shaped Length of head race tunnel = 6500m Value of rugosity co-efficient (assumed) = 0.012 to 0.016 Computations As per IS: code 7396 Part-I
Thoma area of surge tank is given by the formula Ath L.At/B V1
2H0 V12/2g
Sectional area of H.R.T. 5.10m modified horse shoe shaped At = 20.63 Sqm Vel. in H.R.T. = 3.63 m/sec. BV1
2 = Friction losses in the tunnel & other losses = 6.4x3.632x0.0142x6500/(5.10)1.33 = 12.30m
For computation of Thoma area using min. value of rugosity co-fficient Head losses with n=0.014, = 12.30m Head losses with n=0.012, = 9.04m Say 9m Other losses in trash rack approach tunnel & desilting tank = 0.30m
BV1
2 = 12.30+0.30 = 12.60m For n=0.014 And 9.00+0.30=9.30m With n=0.012 Now, Ho = Net head on turbines Ho = Net head - losses in the system Total losses = Losses upto surge shaft + penstock losses Penstock losses, hf = 0.0085x350x4.32²/2x9.81x4.80 D= 4.80m = 0.589m Say 0.60m L= 465m Q= 75 cumecs V= 4.32m/sec. F = 0.0085 Total losses = 12.60+0.60 = 13.20m Say 11m with n=.014 And = 9.30+0.60 = 9.90m with n=0.012 Say 10m H0= (3418.50-3247.00)-10 = 161.50m Ath = 6500x20.63x3.63²/161.50x10x2x9.81 = 55.76m2 Factor for safety = 1.60 Ath = Area required 55.76x1.60 = 89.22m2 Provide 15m φ surge shaft Area of surge shaft = Π/4(15)² = 176.71 Sqm. CALCULATIONS FOR AREA OF ORIFICE
Orifice area is so provided as to satisfy Calame and Gaden condition for max. flow as given below 2*/√2 + ¼ hf ≤ hor ≤ Z*/√2+¾ hf
Here Z* = Vo √L/gxAt/As =3.63 √ 6500/9.81*20.63/176.71 = 31.92m
For N = 0.016 Hf in tunnel system = 16.06m = 31.92/√2+16.06/4 ≤ hor ≤ 31.92/√2+3/4x16.06 = 22.57+4.01≤ hor ≤ 22.57+12.04 = 26.58 ≤ hor ≤ 34.61 For n=0.012 Then 31.92/ √2+9.00/4 ≤ hor 31.92/√2+3/4x9.00 22.57+2.25 ≤ hor 22.57+6.75 24.82 ≤ hor 29.32 Adopt Head loss across orifice = 30m Now hor = Q0
2/Cd2xA0
2x2g A0 = Q/Cd √2g hor = 75/0.62x√19.62x30 A0 = 4.98 Sqm. D = √4.98x4/Π D = 2.52m Provide orifice dia = 2.50m Max. up surge = 13.10m As per surge analysis on computer Min. Down surge = 11.90m Max. upsurge level FRL= 3421+14.96 =3435.96m Say 3436.00m Min. downsurge level MDDL = 3413.50-16.86 =3396.64m Say 3396.60m CALCULATIONS FOR SLOPE OF TUNNEL Invert level of tunnel at RD 0 of tunnel = 3402.50m
C/L of the tunnel at RD 0 = 3402.50+5.10/2 = 3402.50+2.55 = 3405.05m
C/L of tunnel at outlet = MDDL-Losses in HRT- 1.5x orifices losses- depth of orifice-radius of HRT = 3413.50-12.30-1.5(30)-2.50-2.55
= 3413.50-12.30-45-2.50-2.55 = 3351.01m Say 3351.00m Difference in levels = (3402.50-2.55)-3351 = 54.05m (RD 0 & RD 6500) Length of tunnel = 6500m Slope of tunnel = 6500/54.05 = 1:120.25 Say1:120 Now V1 = Q/A = 75/20.63 = 3.63m/sec. V2 = 1/4 R 2/3 S½ = 1/0.014x1.27 2/3(1/120)½ = 7.46m/sec. V2>V1 Hence O.K. PRESSURE SHAFT (Ref. Drawing No. Gharopa-FR-6.) Parameters Design discharge = 75 cumecs Design net head H = 160m Length of penstock = ± 350m Efficiency of turbine = 94% Rated HP of turbine P =1000x75x160x0.94/75 = 150400 H.P. No. of pressure shaft = 1 No.
Hydraulic Design Economical dia of Pressure shaft a) By DOLOND’s FORMULA Diameter = D = 0.176 (P/H)0.466
= 0.176 (150400/160)0.466 = 4.27m b) As per R.S. Nigam’s Hand Book D ≤ [ 1xfxc1xk2xQ3xt/ 1100xK1xH]1/7
Where H = 160+20% Water hammer effect = 192m c1 = 2444 kg/cm2-Allowable stress insteel (0.2x1347+0.8x2728) f = 0.0085 = Friction factor K1 = 75x0.1250 = 9.37 Rs./kg. = Annual cost of pressure shaft per kg. K2 = 2.00 = Value of KWH at generator terminal in same unit t = 365x24x0.50 = 4380 hrs. = Annual duration of operation in hrs. D = [1x0.02x2444x2.00x(75)3x4380/ 1100x9.37x192]1/7= 5.11m Taking average dia of (a) & (b) Average diameter = 4.27+5.11/2 = 4.69m Say 4.70m Velocity in pressure shaft
V = 75/ Π/4(4.70)² = 4.32m/sec. Dia of Branch penstock (3 units) Discharge = 75/3 = 25 cumecs V = 4.32m/sec.
D = √25x4/4.32 x 4/Π = 2.71m Say 2.70m CALCULATIONS FOR GROSS HEAD & NET HEAD F.R.L. in reservoir = 3421.00m MD.D.L = 3413.50m Normal water level = 3413.50+7.50x2/3 = 3413.50+5 = 3418.50m Min. tail water level = 3239.50m Normal tail water level = 3240.00m Max. tail water level = 3247m Max. gross head = Normal reservoir level-Min. tail water level = 3418.50-3239.50 = 179m Min. Gross head = Max. reservoir level -Max. tail water level
= 3421-3247 = 174m Design gross head = 174+2/3 (179-174)
= 177.33m
Total losses from intake to power house = 17.33m
Design Net Head = 180.83-17.33 = 160m TAIL RACE TUNNEL (Ref. Drawing No. Gharopa-FR-7( Sheet 2 of 3). Data Design discharge = 75 cumecs Size shape = 6m, D-shaped Length of tunnel = 1150m Assumed value of Rugosity co-efficient= 0.014
Hydraulic design i) Under normal conditions the TRT will behave as a free flow tunnel V = 1/0.014x( 12.60/10.20)2/3 (1/182.50).5 = 6.08m/sec. Discharge passed = 12.60/6.08 = 76.69cum/sec. ii) Under HFL conditions the TRT will behave as a pressurized conduit Gross cross sectional area of tunnel = [(6x3)+(Π/4x6²/2)] = 32.13 Sqm. Velocity in tail race tunnel = 75/32.13 = 2.33m/sec. Fixation of crest level of T.R.T.
i) Crest level at outfall will behave as a broad crested weir Now Q = CLH3/2 75 = 1.71x6xH3/2 H = [ 75/1.71x6] 3/2 = 3.76 m Crest level at outfall = 3240.00-3.76 = 3236.24m
CHAPTER – VII
POWER POTENTIAL STUDIES
7.0 GENERAL
Bajoli-Holi Hydro-electric Project has been proposed as a run- of- the
river development for generation of hydro-power on Ravi river in
Himachal Pradesh. As a peaking station to operate in western part of
Northern Regional Grid. Installed capacity of the project has been
presently kept as 180 MW comprising 3 units of 60 MW each with
overall efficiency of generation as 0.92.
7.1 PATTERN OF FLOWS IN 90% DEPENDABLE AND 50% MEAN
YEAR
31 years discharge data from June 1972 to May, 2003 in respect of Ravi
river at Kutehr Dam site has been used to develop a flow series for Bajoli-
Holi HEP for power generation. Energy generation has been worked out
for all the years as appended in Table 7.1. .Pattern of flows in 90%
dependable and 50% mean years has been worked out on the basis of
energy generation in 31 years by using Welbull’s relationship P= n/m+1,
where P is percentage exceeding of occurrence, n is the event no. in
descending order and m is total no. of events, presented in Table 7.2.
Flows in 90% dependable and 50% mean years, so worked out are given
in Table 7.3.
7.2 HEAD FOR POWER GENERATION
7.2.1 DESIGN HEAD
Gross head for power generation has been worked as 308.00 m between
Normal water level at diversion site El. 2008 and minimum tail water level
El. 1700. Losses in water conductor system corresponding to design
discharge of 71.74 cumecs from diversion site to generating units has been
worked out as 30.00 m. Design net head therefore has been taken as 278
m. The calculations are as follows:
FRL = 2015 m
MDDL = 1994 m
Normal water level
MDDL + 2/3( (FRL-MDDL) = 1994+2/3(2015-1994) = 2008
Normal Reservoir level at = ± 2008.00 m
Diversion Site
Min. tail water level = ± 1700.00 m
Gross Head = 2008.00 – 1700.00 = 308.00 m
Losses = 30.00 m
Net Head = Gross Head – Losses
= 308 – 30 = 278.00 m
7.3 POWER GENERATION IN A 90% DEPENDABLE YEAR AND
50% MEAN YEAR
Power generation studies in a 90% dependable year corresponding to
installed capacity varying from 90 MW to 210 MW are given in Table 7.4
The energy generation in 90% dependable year corresponding to the
installed capacity of 180 MW is 762.98 GWH. The energy generation in
90% dependable year corresponding to 95% machine availability works
out to be 754.13GWH as shown in Table 7.5.
Power generation studies in a 50% mean year corresponding to installed
capacity varying from 90 MW to 210 MW are given in Table 7.6 The
energy generation in 50% mean year corresponding to the installed
capacity of 180 MW is 861.37 GWH.
7.4 INSTALLED CAPACITY STUDIES
Power generation studies for 90% dependable and 50% mean year pattern
of flows with installed capacity varying from 90 MW to 210 MW have
been done. From the study, the incremental increase v/s installed capacity
curve & total energy v/s installed capacity curve have been drawn as
shown in Plate 7.1 and Plate 7.2 respectively.
It is seen from the curve that there is uniform decline in incremental
increase until we reach at installed capacity of 180 MW. Moreover the
overall plant load factor and .% utilization at 180 MW is 0.48 and 99.36%
respectively.
The project has also been planned as a peaking station for 3 hrs to meet
with the peaking power shortage in the country. Hence keeping in view
the overall PLF of 48% and.% age utilization of 99.36% the installed
capacity has been fixed to be 180 MW.
PARA DESCRIPTION PAGE
7.0 GENERAL VII-1
7.1 PATTERN OF FLOWS IN 90% AND 50% YEARS VII-1
7.2 HEAD FOR POWER GENERATION VII-2
7.2.1 DESIGN HEAD VII-2
7.3 POWER GENERATION IN A 90% DEPENDABLE
YEAR AND 50% MEAN YEAR
VII-2 TO
VII-3
7.4 INSTALLED CAPACITY STUDIES VII-3
TABLE 7.1 UNRESTRICTED ENERGY GENERATION FOR ALL
THE YEARS.
VII-4 TO
VII-7
TABLE 7.2 COMPUTATION FOR DEPENDABLE YEAR ON THE
BASIS OF ENERGY.
VII-8
TABLE 7.3 90% DEPENDABLE AND 50% MEAN YEAR
DISCHARGES
VII-9
TABLE 7.4 ENERGY GENERATION IN 90% DEPENDABLE YEAR
(1987-88).
VII-10 TO
VII-13
TABLE 7.5 ENERGY GENERATION IN 90% DEPENDABLE
CORRESPONDING TO 95% M/C AVAILABILITY.
VII- 14
TABLE 7.6 ENERGY GENERATION IN 50% MEAN YEAR
(1977-78).
VII- 15 TO
VII-19
PLATE-7.1 INSTALLED CAPACITY CURVE - 90% YEAR VII- 20
PLATE-7.2 TOTAL ENERGY V/S INSTALLED CAPACITY CURVE
90% YEAR
VII- 21
TABLE -7.7 SUMMARY TABLE VII- 22
TABLE -7.8 SUMMARY TABLE VII- 23
ANNEX-7.1 COMMENTS OF CEA ON DRAFT PFR AND REPLIES
THEREOF
VII- 24 TO
VII-28
REPLIES TO THE COMMENTS RAISED BY THE DIRECTOR (HP&I), NEW DELHI VIDE HIS LETTER NO. 7/9(HPSEB)/HP&I/2004/1315 DATED 19.7.04 IN RESPECT OF BAJOLI-HOLI HEP (180 MW) ARE DETAILED AS BELOW:-
GENERAL
1. Initial Environmental studies carried out by HPSEB, Conservator Cell, and the
studies done by NRSA, Hydrabad, have been collected and incorporated to the
PFR.
2. Financial Parameters have been adopted as per guidelines furnished vide letter No.
7/9/HPI-2003/1118-1123 dated 21.10.2003.
3. Cost estimate has been prepared as per the guidelines. Tariff calculation by
considering IDC & without free power to home state shall be carried out at DPR
stage.
4. Action shall be taken during DPR stage.
5. Approval of Hydrology is under process with CWC.
6. Action shall be taken during DPR stage.
7. Matter shall be taken up by the Chief Engineer (SP), HPSEB, Shimla with SP &
PA division of CEA.
8. Executive Summary as desired shall be sent separately.
9. Report of GSI has been incorporated to the PFR.
POWER POTENTIAL STUDIES
1. The power potential study has been carried out as per the data available and the
installed capacity of 180 MW has been fixed by keeping inview the curve drawn
between Installed capacity versis incremental increase in energy. The review of
installation in view of peaking operation and higher load factor during lean season
shall be carried during detailed study for preparation of DPR.
2. Detailed study shall be carried out of DPR stage.
3. Area capacity curve has been incorporated as Plate 5.3 under Chapter No.V
Hydrology.
4&5 The summary of studies indicating load factor yearly inflows, annual energy
generation & incremental increase in energy shall be presented in tabular form in
DPR.
6. Recommendation for further studies required for preparation of DPR is as under.
i) The consistency of the observed data will be got checked at the DPR stage,
as the concurrent data of other sites in the basin is being collected. ii) The layout of the project has been finalized on the SOI sheet in the scale of
1:50,000. The detailed surveys on the larger scale will be carried out and any change in gross head/layout will be taken care of.
HIMACHAL PRADESH STATE ELECTRICITY BOARD NO.HPSEB/DP/BAJOLI-HOLI/2004- Dated____/8/04 To The Chief Engineer (HP & I), Central Electricity Authority, Room No. 407 (N), Sewa Bhawan, R.K.Puram, New Delhi-66. Sub: PFR of BAJOLI-HOLI HEP – Submission thereof. Ref: This office letter No. HPSEB/DP/BAJOLI-HOLI/04-724-27 dated 30.6.04 Sir, In continuation to this office letter under reference, enclosed please find herewith PFR of Bajoli Holi HEP (25 copies) for kind reference at your end, please. It is further added that the replies to the comments conveyed by your office in respect of hydrology, power studies and general, have been attended and replies thereof appended in PFR. This is for your kind information. DA: As above (25 Copies) Yours faithfully, Alternate Nodal Officer-Cum
Director Planning, Circle No.1, HPSEB, Sundernagar (HP).
Copy to above for kind information forwarded to : i) Nodal Officer -Cum Chief Engineer (I&P), HPSEB, Sundernagar ii) Chief Engineer (P&M), HPSEB, Vidyut Bhawan, Shimla-4. iii) Chief Engineer (SP), HPSEB, Vidyut Bhawan, Shimla-4.
Alternate Nodal Officer-Cum Director Planning, Circle No.1, HPSEB, Sundernagar (HP).
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CHAPTER – VIII
POWER EVACUATION 8.0 ELECTRO MECHANICAL WORKS
8.1 GENERAL
Bajoli Holi Hydel Project utilizes the flows of Ravi river and is located in
Chamba Distt. of Himachal Pradesh . A net head of 278 Mts. has been
utilized to generate 180 MW of power at Barola power house .
The salient features of Bajoli Holi HEP are as under:-
Net Head 278 Meters
Installed capacity 180 MW
No. and size of units 3 units of 60 MW each.
Type of Power House Underground.
Cost of Electrical Works:-
P-production Rs. 16560.00 Lacs.
T- Transmission Rs. 3602.54 Lacs.
8.1.2 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. 2004-2005.
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8.2 POWER HOUSE
The underground power house ( 50 m (L) x 13 m(W) x 35 m(H)) will have
3 generating units of 60 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 15
m. 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.
8.2.1 MECHANICAL EQUIPMENT
8.2.1.1 TURBINES
The vertical shaft , Francis turbine of 61.22 MW capacity with a rated
synchronous speed of 500 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.
8.2.1.2 GOVERNOR
Since Bajoli Holi power house will be connected with Kutehr pooling point,
and shall also be operated as peaking station in tandem with other up
stream projects, it is of great importance that the governor accuracy and
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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.
8.2.1.3 MAIN INLET VALVES
A main inlet valve of the butterfly 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 shall be 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.
8.2.1.4 COOLING WATER AND FIRE PROTECTION SYSTEM
A pumping system would be provided to supply adequate quantity of water
from the tail race for cooling of the turbine and generator bearings,
generator air coolers and selected plant services.
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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.
8.2.1.5 POTABLE WATER AND SANITARY DRAINAGE
Water from the cooling water system would be used to supply the plant’s
potable and sanitary water needs. The potable water would be filtered and
chemically treated as required. Sanitary sewerage would be treated in a
septic system before discharge in to tail race of power plant.
8.2.1.6 COMPRESSED AIR SYSTEM
A high pressure compressed air plant would be installed to meet the
requirements of the governor oil system and the oil pressure system of the
spherical valves.
A low pressure compressed air plant would also be installed to meet the
requirements of the station pneumatic tools and other general purpose in the
power house.
8.2.1.7 OIL SYSTEM
A portable dehydration unit comprising of oil heaters, Filters, tank etc.
would be provided in the power station for the treatment of governor/
Bearings and switch gear oils.
8.2.1.8 VENTILATION AND AIR CONDITIONING
Power house would be provided with ventilation system as required for the
underground power house work areas and offices. An air conditioning
system would be provided to maintain the control room at the selected
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design temperature and humidity levels. The temperature and humidity
level would be selected to suit the requirements of equipment and staff.
8.2.1.9 POWER HOUSE CRANE
In order to expedite the completion of various construction activities of the
power house, 1 Nos. electric over head travelling bridge crane with capacity
of 130/30 tonnes would be installed in the power house primarily for
erection, maintenance and repair of the generating units. The cranes would
be equipped with motor control system providing suitable procedure for
equipment erection.
8.2.2 ELECTRICAL EQUIPMENT
8.2.2.1 GENERATOR
Each generator shall be of vertical shaft, salient pole type, Synchronous
generator directly coupled to the hydro turbine and having a rated out put of
66.67 MVA with 0.9 lag power factor. The generator bearing arrangement
shall be of conventional type i.e. suspended type. It is proposed to equip the
generators with dynamic braking in addition to the friction brakes. The
generator shall have class-F insulation in line with modern practice and
temperature restricted to class-B insulation.
The generator will be air cooled with a closed ventilation system using air
water heat exchanger placed around the stator frame. The generators are
proposed to be equipped with the following electrical protection equipment
High speed differential protection for generator.
Generator Over Voltage protection.
Back up over current protection.
Stator earth fault relay protection.
Negative Phase Sequence Current protection.
Rotor Field Circuit earth Fault Relay & protection.
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Loss of excitation relay schemes.
Generator thermal relay protection.
Phase balance relay.
8.2.2.2 EXCITATION SYSTEM
The excitation system of the generator will be of static type and will include
static type voltage regulator of latest design, field suppression equipment
and the associated accessories.
The power for the excitation system will be taken from the generator main
bus by means of a dry type or epoxy encased step down transformer. The
excitation system will be self contained requiring only an external power
source for field flashing at unit starting. The field flashing supply will be
taken from the station battery.
The excitation system including the voltage regulator will be placed in the
cubicles adjacent to the generator pit.
8.2.2.3 GENERATOR SWITCH GEAR AND CONNECTING CABLES
Each generator shall be connected to its step up transformer by means of 11
kV bus ducts. Current transformers required for protection, control and
metering will be located and form part of the bus ducts assemblies.
The generator switch gear will be of the metal enclosed type placed in a
separate room close to the generator. It will include the generator phase
equipment. The equipment for the generator neutral side will be placed in a
cubicle adjacent to the generator pit.
8.2.2.4 GENERATOR TRANSFORMERS
10 Nos. Indoor generator transformers of 25 MVA , 11/ 220/√3 kV , single
phase , 50 Hz rating will be provided and placed in a separate underground
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cavity ( 80 m(L) x 16 m(W) ) on the down stream side of power house
cavity. The OFWF type of cooling is proposed for generator transformers.
8.2.2.5 CONTROL AND MONITORING EQUIPMENT
The plant will be designed to be operated as an attended type. Unit control
will be provided locally while central control will be from various control
panels located in the control and relay room of the power house. Control
equipment will include metering and control panels, protections for
supervision and operation of the generator turbine, 11 kV switch gear ,
auxiliary power system, transformers and 220 kV switch gear.
The control equipment will also include the PLC and Telecommunication
equipment required for the transmission lines. Provision for connection to
the state load dispatch center will also be provided.
8.2.2.6 STATION SERVICE/ AUXILIARY SUPPLY
The station service supply is proposed to be taken through 33 kV Local
Distribution system. In addition, for reliability, 2X250 KVA DG sets shall
also be provided for the black start capability. This arrangement will also
feed local area , Colony, head works etc. The unit auxiliaries shall be fed
through 11/0.415 kV, 500 KVA transformers connected to each generator.
The auxiliaries can also be fed from 2 Nos., 33/0.415 kV, 500 KVA station
auxiliary transformers, which are connected to 33 kV bus connected to 33
kV local supply.
8.2.2.7 POWER PLANT GROUNDING
The power station will be provided with a complete earthing system. All
exposed conductive parts and equipment in the powerhouse and switchyard
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will be connected to the grounding system. The grounding system will be
designed to minimize the “Safe” and “Touch” potential within acceptable
limits.
8.2.2.8 LIGHTING
The power plant lighting, following normal practice, will comprise of
interior and exterior lights as appropriate. While the majority of the
illuminaries will be AC powered, emergency lighting will be DC supplied
from station battery system. The emergency lighting will be provided only
for essential locations e.g. control room, exits etc.
8.2.2.9 SWITCH YARD AND SWITCHING SCHEME
The project is proposed to be interfaced with the 220 kV Kutehr HEP. The
evacuation arrangement has been made after taking in to consideration the
constraints on right of way, reliability and the quantum of power that shall
be injected in to 220 kV Kutehar HEP. Schematic diagram showing the
interconnection of Bajoli Holi with other identified projects is as per Annex.
A. Due to space constraints, 220 kV Gas Insulated Switchgear has been
proposed and shall be housed on a floor located just above the transformers
in the transformer cavern. Single breaker double bus bar arrangement has
been proposed after giving due consideration to its reliability, stability, easy
maintenance and accessibility. The GIS switchyard has 3 generator
transformer bays, one bus coupler bay and two feeder bays. The connection
of the Pot yard with the underground GIS switchyards shall be made via
220 kV, XLPE cables. In addition to this, space for 2 Nos. 220 kV feeder
bays shall be kept for up stream projects i.e. Bara Bangal (200 MW).
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8.3 TRANSMISSION OF POWER
Considering the amount of power to be evacuated and the distance
involved, it has been proposed to inject the power generated at Bajoli Holi
power house in to 220 kV Kutehar HEP. For wheeling of power that shall
be accumulated at Kutehar HEP, 220 kV D/C line from Kutehar to
Hamirpur 2x0.5 or 4x0.5 conductor depending upon total firmed up
capacities of projects up stream of Kutehar HEP(as per decision taken
during the 16th standing committee on Transmission System Planning) in
Northern Region held in NREB on 24.3.2004) shall be laid.
8.4 ESTABLISHMENT
The electrical works of the project are proposed to be completed with in 5
years time. Accordingly, the provision of regular establishment required for
to do electrical works in this time frame has been made in the estimate. The
design procurement, inspection, erection and commissioning of electrical
works of the project shall be done departmentally.
The provision of staff has been made as per the CEA’s norms intimated
from time to time
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PARA DESCRIPTION PAGE
8.0 ELECTRO-MECHANICAL WORKS. VIII-1
8.1 GENERAL VIII-1
8.1.2 SCOPE VIII-1
8.2 POWER HOUSE. VIII-2
8.2.1 MECHANICAL EQUIPMENT VIII-2
8.2.1.1 TURBINES VIII-2
8.2.1.2 GOVERNOR VIII-2 TO VIII-3
8.2.1.3 MAIN INLET VALVES VIII-3
8.2.1.4 COOLING WATER AND FIRE PROTECTION
SYSTEM.
VIII-3 TO VIII-4
8.2.1.5 POTABLE WATER AND SANITARY DRAINAGE VIII-4
8.2.1.6 COMPRESSED AIR SYSTEM VIII-4
8.2.1.7 OIL SYSTEM VIII-4
8.2.1.8 VENTILATION AND AIR CONDITIONING VIII-4
8.2.1.9 POWER HOUSE CRANE VIII-5
8.2.2 ELECTRICAL EQUIPMENT VIII-5
8.2.2.1 GENERATOR VIII-5
8.2.2.2 EXCITATION SYSTEM VIII-6
8.2.2.3 GENERATOR SWITCH GEAR AND
CONNECTING CABLES.
VIII-6
8.2.2.4 GENERATOR TRANSFORMERS VIII-6
8.2.2.5 CONTROL AND MONITORING EQUIPMENT VIII-7
8.2.2.6 STATION SERVICE/AUXILIARY SUPPLY VIII-7
8.2.2.7 POWER PLANT GROUNDING VIII-7
8.2.2.8 LIGHTING VIII-8
8.2.2.9 SWITCH YARD AND SWITCHING SCHEME VIII-8
8.3 TRANSMISSION OF POWER VIII-8 TO VIII-9
8.4 ESTABLISHMENT VIII-9
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CHAPTER - IX
ENVIRONMENTAL ASPECTS
9.0 DESCRIPTION OF THE PROJECT
The proposed Bajoli Holi HEP is a run of the river scheme on Ravi
river to harness the power potential between village Bajoli and Barola.
The scheme envisages diversion of 71.74 cumecs discharge of Ravi,
near 200 m down stream of the confluence of Channi nallah with river
Ravi by constructing a diversion structure (about 30 m high) through
an underground desilting structure, a 5 m dia 14.6 km long HRT, surge
shaft and a 4 m dia 475 m long pressure shaft to generate 180 MW of
power in an underground power house near village Barola by utilising
a gross head of about 308 m. The water will be further discharged to
Kuther reservoir.
9.1 DESCRIPTION OF ENVIRONMENT
9.1.1 PHYSICAL RESOURCE
9.1.1.1 HYDROLOGY
The area in question is drained mainly by Ravi river. A large number
of nallah drain directly in to the Ravi river. In the propose project area,
Sarontha Nallah and Sal nallah drains into the Ravi river
9.1.1.2 GEOLOGY
Most of the area of the area is as yet geologically unmapped. A great
mass of the mountain is formed of ancient rock of silurian age, resting
on a central mass of granite or granitoid gneiss. Nearly all the hill
ranges of the Himalayas follow a definite pattern of strata. They
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usually lie in the east-west direction with some variations. The strata
dip to the north barring some variations due to orogenic movements
and local disturbances. This east-west sweep of the ranges has given
rise to markedly south and north exposed slopes, and hence to
different rock weathering conditions and vegetative cover due to the
varying duration of light.
All over the tract, schist occurs in different forms such as shales, slates,
gneisses, argillaceous clay, etc. The schists provide easily worked
building stones, while slates provides excellent roofing material of
good quality. Underlying rock of Dhauladhar range are granite and
gneiss almost uniform in character throughout. At the lower elevations
the rock system, mainly on the northern and eastern slopes, is very
unstable, weak and friable nature, readily prone to disintegration. The
terrain in such parts is highly susceptible to landslides, land-slips and
erosion. The sub-soil is fairly hard, generally argillaceous shale, which
is often fissured, and easily subject to disintegration near the surface
when exposed. The soil depth is inversely proportional to the slopes.
On ridges and spurs, and precipitous and southern aspects, the soil
tends to be shallow and dry with numerous out-crops of bare rocks.
9.1.2 ECOLOGICAL RESOURCE
9.1.2.1 FORESTS
The composition of the forest vegetation and its evolution is influenced
by the character of the rocks/soil underlying. The main forests in the
area are of Kail and Chilgoza. The density varies from good to sparse
and scattered. In some areas which were earlier shown to have Kail
forests are now having Chilgoza trees.
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9.1.2.2 FLORA AND FAUNA
9.1.2.3 FLORA
The main parts are located on the right bank of the river which is
almost barren. Very few patches of Kail trees are seen. On higher
elevations the vegetation is better. However, the right bank has
moderate tree cover of various species. The composition and condition
of the crop varies with altitude and aspect. In the lower area Kail and
Deodar are found mixed with Oaks whereas further upward Spruce and
Fir forests are found as mixed crop or in pure form. Kail is prominent
on southern aspects whereas Deodar, Spruce and Fir are mostly
confined to the cooler aspects.
The right bank in particular has a good stock of medicinal plants on
higher altitudes.
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Scientific name Common Name English Name
Abies pindrow
Acer caesium
Aesculus indica
Alnus nepalensis
Alnus nitida
Cedrus deodara
Celtis australis
Corylus colurna
Cupressus torulosa
Ficus bengalensis
Ficus religiosa
Ficus roxburghii
Fraxinus excelsior
Fraxinus floribunda
Grewia vestita
Juglans regia
Litsaea glutinosa
Litsaea umbrosa
Machilus odoratissima
Morus alba
Morus serrata
Myrica nagi
Rai
Mandar
Goon
Piak
-do-
Diyar
Khirak
Thangi
Devidiyar
Bar
Pipal
Trambal
Sanooh
-do-
Dhaman
Akhrot
Chirindi
-do-
-do-
Karun
-do-
Kaphal
Silver Fir
Mapple
Horse Chest Nut
Alder
-do-
Deodar
Nettle Tree
Hazlnut
Cyprus
Ash
-do-
Walnut
Mulberry
-do-
Olea cuspidata
Picea smithiana
Pinus gerardiana
Pinus roxburghii
Pinus wallichiana
Populus alba
Populus ciliata
Punia granatum
Kahu
Tosh
Neoza
Chir, Chil
Kail
Pahari Pipal
Chaloon
Daru
Wild Olive
Spruce
Chilgoza Pine
Chil Pine
Blue Pine
Poplar
-do-
Wild Pomegranate
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Pyrus communis
Pyrus malus
Quercus dilatata
Quercus incana
Quercus semicarpifolia
Rhododendron arboreum
Robinia pseudoacacia
Salix alba
Salix babilonica
Taxus baccata
Nakh
Seo
Moru
Ban
Kharsu
Cheo
----
Badha
Badha ( Majnu )
Barmi
Pear
Apple
Green Oak (Middla Zone)
White Oak ( Low Level)
Brown Oak (High Level)
Red Rhododendron
----
Willow
-do-
Yew
B. SHRUBS
Agave americana
Ainslea aptera
Berberis aristuta
Chenopodium album
Cotoneaster acuminata
Cotoneaster bacillaris
Cotoneaster microphylla
Cotoneaster vulgaris
Daphne cannabina
Dendrocalamus strictus
Desmodium tiliaefolium
Deutzia corymbosa
Ramban
Mukh Nihani
Kemal/Kasmal
Bathu
Rheuns
-do-
-do-
-do-
Niggi
Bans
Pre
Batti
Century Plant
Airon's Rod
----
----
----
----
----
----
----
----
----
Wild Syringe
Eurphobia royleana
Fragaria vesca
Galium asperifolium
Galium ptunifolium
Girardiana heterophylla
Hamiltonia suaveolens
Ilex dipyrena
----
Strawberry
-do-
----
----
Ain
Padara
----
strawberry
-do-
----
----
----
----
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Indigofera gerardiana
Indigofera hersuta
Indigofera pulchella
Juniperus communis
Juniperus recurva
Lonicera angustifolia
Lonicera quinquilocularis
Mimosa rubicaulis
Oxalis corniculata
Parrotia jacquemontiana
Plantago lanceolata
Plantago tibetica
Pletranthus rugosus
Potentilla Spp.
Primulla Spp.
Prinsepia utilis
Pteris aquilina
Rhamnus purpurea
Rhus cotinus
Rhus parviflora
Rosa macrophylla
Rubus biflorus
Rubus niveus
Kanderu
Kathi
----
----
Bither
-do-
Kantias
Bakhru
----
Malori
Killar
Isabgol
----
Kuthal
----
----
Kangora
Lingar
Luhish
Tung
Tungla
Karer, Bangulab
Akhre
The Holly
----
----
----
Cedar
-do-
Honey Suckle
-do-
----
----
Wych hazel
----
----
----
----
----
----
----
----
----
----
----
Raspberry Red
Sarcococca pruniformis
Sarcococca saligna
Staphylea emodi
Strobilanthus dalhousianus
Trifolium repens
Viburnum cotinifolium
Viburnum foetens
Viburnum nervosum
Diun
-do-
Nagdaun, Chitra
----
----
Talanj
-do-
-do-
----
----
Snake wood
----
Clover white
----
----
----
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Viburnum stellulatum
Woodfordia floribunda
Woodfordia fruticosa
-do-
Dhawa
-do-
----
----
----
C. CLIMBERS
Vitex negundo
Hedera helix
Smilex parviflora
Vitis Latifolia
Vitis semocordata
Bannah
Kural
----
Panibel
-do-
----
Ivy
----
The Virginian Creeper
-do-
D. MEDICINAL PLANTS
Aconitum heterophyllum
Aconitum chesmanthum
Arisaema flavum
Arisaema helleberifolium
Arisaema wallichiana
Asparagus racemosus
Atropa acuminata
Atropa belladona
Cinnamomum tamala
Digitalis purpurea
Dioscorea bulbifera
Dioscorea deltoidea
Patis
Mohri
Samp-ki-makki
Ki-kukri
-do
Satawar
----
Shafoo
Tejpat
----
Khildri
-do-
Medicinal herb
-do-
----
Cobra Plant
-do-
----
----
Belladona
----
----
----
----
Hydrocolyle asiatica
Jurinea macrocephala
Mentha acquatica
Ocimum Spp.
Brahmi-Buti
Dhup
Pudina
----
----
----
Mint
----
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Onosrna bracteatum
Picrohiza kurrooa
Podophyllum emodi
Rumex nepalensis
Salvia glutinosa
Saussurea lappa
Saxifraga ligulata
Taraxacum officinale
Thalictrum foliolosum
Verbascum thapsus
Valeriana wallichii
Viola odorata
Viola serpens
Withania somnifera
Rarra (Rattanjot)
Kaur
Ban Kakru
Amlora
Makhiar
Kuth
Pathartor
Dudhali
Machhar Mar
Giddar Tamaku
Smak, Nihani
Banafsha
-do-
Ashawgandha
----
Medicinal Plant
----
----
Dog Flower
----
----
----
----
----
----
----
----
----
9.1.2.4 FAUNA
Although the wild Life’s presence on the right bank is very rare, the
most common animals and birds found in vicinity are as follows.
1. GHORAL (Nemorthaedus Goral)
2. KAKKAR- Muntjac or barking deer (Muntiacus muntjak)
3. KASTURA (Moschus moschiferus)
4. BAGHERA OR LEOPARD (Panthera pardus)
5. KALA BHALU OR HIMALAYAN BLACK BEAR
(SELENARCIOS THIBETANUS)
6. LAL BHALU OR HIMALAYAN BROWN BEAR (Ursus
arctos)
7. GORTHU OR THE HIMALAYAN PINE MARTIN (Martes
flavigula)
8. THE INDIAN PORCUPINE (Hystrix indica)
9. EAN OR FLYING SQUIRREL (Hylopetes)
10. CHUKOR (Alectoris gracca)
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11. RED JUNGLE FOWL (Gallus gallus)
12. KALESHA (Genuocus albicratatus)
13. CHEER PHEASANT (Caterus wallichi)
14. KOKLAS PHEASANT (Varasis macrolopha)
15. BLACK PATRIDGE (Francolinus francolinus)
16. DOVE OR GHUGI (Chalcuphaps indica)
17. GREY QUAIL (Coturnix conurnix)
9.2 BASELINE ENVIRONMENTAL STATUS
9.2.1 CLIMATE AND TEMPERATURE
The climate is markedly temperate and varies with the altitude.
Since most of the area of the tract lies on higher elevations and
northern aspects, so cool weather prevails during most part of the
year.
Seasons are well marked. The spring season is cool bright and free of
haze and mist or dust and snow deposits still persists above 1830
meters. April slowly gives way to the much steadier months of May
and June when the sun shines, the light brightest and warmest, with
occasional light showers and the weather is tolerably warm. The
monsoon generally starts in the first week of July and lasts upto the
end of August. There are occasionally very heavy rains, which bring in
devastating floods in the streams and nullahs and landslides or land
slips (locally called ghaars). September and October is cool bright and
free of haze and dust, with occasional light rains. November is cool
and dry and by the middle of this month rain, hail, sleet and light
snowfall begin to visit the area above 1800 meters. Snowfall is almost
a regular feature from December to middle of March. It accumulates as
much as 9 meters at 2700 meters elevation and above and does not
persist longer below 1800 meters of elevations and southern slopes.
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9.2.1.1 TEMPERATURE, RAINFALL AND SNOWFALL DATA
TEMPERATURE OF BHARMOUR
Maximum Minimum
January 17 -3
February 14 -5
March 22 1
April 24 1
May 27 10
June 31 14
July 28 15
Aug 26 15
Sep 28 13
Oct 23 9
Nov 20 5
Dec 7 1
RAINFALL
Details of average monthly rainfall for meteorological station Holi
(Elevation 6000 feet) for the last ten years are given below:-
Rainfall (in mm) and Snowfall ( in cm ) during the
month
January February March
Rainfa
ll
Snowfa
ll
Rainfa
ll
Snowfa
ll
Rainf
all
Snowfa
ll
45.84 10.55 68.46 28.36 176.18 6.55
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Rainfall (in mm) and Snowfall ( in cm ) during the
month of
April May June
Rainfa
ll
Snowfa
ll
Rainfa
ll
Snowfa
ll
Rainf
all
Snowfa
ll
85.59 0.18 102.73 ---- 32.73 ----
Rainfall (in mm) and Snowfall ( in cm ) during the
month of
July August September
Rainfa
ll
Snowfa
ll
Rainfa
ll
Snowfa
ll
Rainf
all
Snowfa
ll
107.60 ---- 89.91 ---- 67.37 ----
Rainfall (in mm) and Snowfall ( in cm ) during the
month of
October November December
Rainfa
ll
Snowfa
ll
Rainfa
ll
Snowfa
ll
Rainf
all
Snowfa
ll
24.36 ---- 22.29 1.27 87.02 13.05
The bulk of the precipitation is received in the form of sleet and snow
from the mid of November to middle of March. Rainfall is also good
during monsoon from middle of July to end of August. The difference
in the distribution of the snowfall is less pronounced. Generally, the
inner valleys experience a heavy snow fall , where it stays longer.
Droughts occur from April to middle of June and during middle of
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September to November. Prolonged severe droughts are common and
that have adverse effect on the establishment of regeneration.
Air, Water, Soil and Sound data will be collected at the time of
doing detailed EIA.
Since this is pre feasibility report, this has not been done at this stage.
9.3 ENVIRONMENT IMPACT ASSESSMENT AND EVALUATION
9.3.1 IMPACT IDENTIFICATION
Environmental impacts both direct and indirect on various
environmental attributes due to Bajoli Holi Hydropower project in the
surrounding environment, during construction & operational Phase are
discussed.
9.3.2 IMPACT IDENTIFICATION DURING CONSTRUCTION
PHASE
The impacts due to the construction of Bajoli Holi HEP and power
house installation commence from the exploration activities,
construction of barrage, tunnels and approach roads, etc., and may
continue up to generation of hydel power, with the nature and extent of
impacts varying throughout the stage of project development.
Activities like site preparation, approach roads, excavation, drilling,
blasting, foundations, tunneling, deployment of machinery, erection,
transportation, dumping are taken up during construction phase. The
likely impacts on the environment due to these activities are listed in
the table.
Tunneling and foundation works will involve land excavation, filling
and concrete works affecting environment by noise and dust pollution.
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Deployment of machinery, approach roads construction and erection
work will also result in dust, noise pollution and vehicular traffic.
Material handling and transportation may significantly increase noise
pollution. The Muck produced will be in huge quantity and it will pose
an environmental threat unless properly managed.
The labour for various activities during the construction phase shall be
engaged. Some essential services are also required to be provided. This
will have an impact on drinking water supply and sanitary facilities.
Economy of the nearby area will be improved due to increased job
opportunities with corresponding increase in income. Other associated
business activities like transport, hotels, consumer goods etc., will also
be benefited.
The major environmental parameters likely to be effected during
construction phase are muck, noise, dust pollution and sanitation.
Water spraying during high dust will minimise the dust level to some
extent. A proper temporary housing with water supply and sanitation
for workers should be planned. The effect due to construction phase is
however, of temporary in nature and has no permanent effect on
environment.
Construction
Phase
Activity Potential Environmental
Impact
Clearing and grading Negligible
Temporary facilities, such
as, sheds approach roads,
sanitary facilities.
Muck, Dust emission and
change in traffic intensity.
Earth work comprising of
excavation and trenches.
Muck, Soil erosion, run off,
increase in traffic, Dust
emission
Site work /
providing other
facilities.
Foundation work, piling and
construction of check dams.
Muck, Dust, visual and
noise pollution
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Construction of permanent
structures like roads, colony
etc
Muck, Dust and noise
pollution
Mechanical erection and
utility systems.
Dust, noise and visual
impact.
Excavation Muck, Dust, soil erosion,
wastewater generation and
noise
Drilling and blasting Muck, Dust, noise and
health hazards
Dumping Dust, noise and visual
Construction of
approach roads,
tunneling works
and construction
of under ground
Power Station Transportation Dust, noise and visual
9.3.3 IMPACT IDENTIFICATION DURING OPERATIONAL PHASE
There would be little environmental and ecological changes during the
operational phase. The main activities that may cause environmental
impact on the surrounding environment during project completion and
after during operation are:
i. Transportation of excessive solid waste material (muck)
ii. Dumping of solid waste material
iii. Removal of temporary facilities, cleaning etc.
During the project completion the likely potential environmental
impacts are due to dust and noise.
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Operation Phase Activity Potential Environmental
Impact
Down stream erosion of
River bank and bottom
Release of water Down stream flow variation
Impairment of water quality
Silting in the area behind
barrage
Accumulation of back water Dumping of solid waste
Ecological hazard
9.4 PREDICTION OF IMPACTS
The impact during the construction of Bajoli Holi HEP on environment
(air, water, noise, land etc. are predicted in this section. The
construction activity may cause some adverse impacts on the
surrounding environment unless proper environmental management
plan is adopted.
9.4.1 IMPACT ON AIR ENVIRONMENT.
Considerable amount of air pollution will be caused during different
stages of construction of tunnels, barrage, roads and other operations
such as excavation, drilling, blasting, loading and transportation of
material. Suspended Particulate Matter (SPM) is the main pollutant
during construction. Most of the dust arises from drilling, blasting,
excavation, crushing and transportation operations. Large quantities of
dust become wind borne and are carried away from overburden dumps.
The fugitive dust released during the construction activities may cause
immediate effect on the construction workers who are directly exposed
to the fugitive dust. Vegetation will also be adversely affected as
deposition of dust on the leaves will choke the photosynthesis activity,
which, in turn, will have adverse effect on the health of the plants.
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However, the dust does not travel to longer distance because the
project site is located in between hills and V-shaped valleys.
9.4.2 IMPACT ON NOISE ENVIRONMENT
The noise will be generated at the time of construction of barrage,
powerhouse, tunnel boring machine operations, pumps, drilling
machines, dumpers, etc. Continuous exposure of workers to high level
of noise may result in annoyance, fatigue, and may cause temporary
shift of threshold limit of hearing and even permanent loss of hearing.
During operational phase, noise level will be increased due trouncing
machinery and vehicular movement in the area. However, these
impacts are only localised.
9.4.3 IMPACT ON WATER ENVIRONMENT.
During the construction of barrage, tunnel, and power house surface
water (river water) may get polluted due to the generation of large
quantities of suspended particulate matter at the time of transportation
of muck and waste water (sewage) coming from temporary
arrangements like offices, labour camp sheds, etc.,
9.4.4 IMPACTS ON FLORA AND FAUNA
The various plant and animal species available in the region have
already been described. There are no endangered species in the region.
There are no Wild Life Sanctuary or National Park in the area.
Every Plant species and wild life species whether mammal, bird,
reptile, aquatic or amphibian plays an important role in the
maintenance of balance of nature and is useful to mankind in many
ways. Every individual animal, bird or insect has been endowed with
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certain specific protective measures so that it can protect itself and
reproduce, thus ensuring the existence of the species. However, the
project activities will not have any significant effect on the Forest and
Wild Life except for removal of bare minimum number of trees.
However, Compensatory afforestation will be done as per the general
stipulations given by the Govt of India MoEF at the time of sanction of
diversion of Forestland
9.4.5 E. R & R ASPECTS
Since the Project is a run-of-the-river type and there is no storage,
therefore, there is no submergence. Hence, no dwellings, houses or
hamlets will be submerged. So, there is no displacement and
resettlement is involved.
9.4.6 ENVIRONMENTAL MANAGEMENT PLAN (MITIGATION
MEASURES)
Environmental Management Plan (EMP) aims at the preservation of
ecological system by considering certain mitigating measures at the
proposed site. The mitigation measures are used to minimize or
prevent adverse impacts on environment due to the proposed
development activity . Some of the major criteria governing the
environmental measures will be adopted, and the same is described in
the following paragraphs.
9.4.6.1 ENVIRONMENTAL MANAGEMENT
The EMP is required to ensure sustainable development in the study
area of 10 Km radius of the proposed Bajoli Holi HEP site.
Government regulating agencies like Pollution Control Board working
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in the region and more importantly the people living in the area need to
extend their co-operation and contribution in this direction.
It has been evaluated that the study area shall not be affected adversely
with the proposed activity and likely to get new economical fillip due
to hydel power generation, not only for the study area but also for the
region as a whole.
The majority of the environmental impact pertains to the construction
phase. It is planned to take corrective measures to ensure that these
effects are kept to bare minimum. The EMP will therefore, be initiated
during planning stage itself.
Catchment Area Treatment Plan, which will be prepared at a later stage
will form part of the Environmental Management Plan
9.4.7 ENVIRONMENTAL MANAGEMENT AT CONSTRUCTION STAGE
9.4.7.1 SITE PREPARATION
Dust emission (fugitive) and solid waste will be generated during
initial site preparation activity and there will be slight increase in the
noise levels around the site. The environmental impacts during the
clearing or clearing for site preparation will be temporary, localised
and negligible. Water sprays at appropriate location will be provided
for dust suppression, hence reducing the impacts. Solid waste will be
disposed off along with the muck at the designated sites.
9.4.7.2 CONSTRUCTION
9.4.7.2.1 AIR ENVIRONMENT
As discussed earlier, construction of Bajoli Holi HEP and powerhouse
activities will generate large quantities of dust during drilling, blasting,
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loading and transportation operations. The following measures are
required be taken to mitigate the fugitive dust from different
operations.
To avoid the dust generation from the drilling operations, wet-
drilling methods will be adopted.
Ceasing dust -generating activities during high winds
Covering of vehicles carrying solid waste (muck).
Watering of haul roads and other roads at regular intervals
Plantation near muck disposal places and dumping yards.
9.4.7.2.2 NOISE ENVIRONMENT
The major noise-generating sources from the proposed activity are
working machinery, blasting and movement of vehicles. The following
control measures are to be undertaken to bring down the noise levels.
Traffic (vehicular movement) to be managed to produce a
smooth flow instead of a noisier stop -and start flow.
Ensuring timely preventive maintenance of the equipment
involved. Since a well maintained equipment is generally
quieter than poorly maintained equipment.
Ensuring usage of personal protective devices i.e., earmuffs and
earplugs by workers, working in high noise activity centers.
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Plantation in the vicinity of the construction area will further
reduce the noise levels.
9.4.7.2.3 WATER ENVIRONMENT
During construction phase the wastewater (sewage) coming from
temporary arrangements like offices, labour camp sheds, canteens etc.,
and impact due to soil erosion during monsoon period may cause
surface water pollution.
Some of the control measures adopted for controlling water pollution
are as follows:
Establishing septic tanks followed by soak pits to treat the
domestic waste water generated from the offices, canteens ,
labour camp sheds.
Construction of Check dams /rock fill dams, wherever
necessary to reduce siltation and suspended solids.
9.4.8 GREEN BELT DEVELOPMENT (COMPENSATORY
AFFORESTATION)
Afforestation is proposed to be done in open areas with moderate
slope. This has to be supplemented with engineering/vegetative works
like gully plugging and check dams etc where ever required. The
planting area should be closed to grazing, lopping quarrying etc. For
proper protection, it is necessary that the area is fenced and the fence is
maintained properly. Plants need to be protected till they attain a
height, which is above grazing level.
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21
9.4.8.1 DISPOSAL OF MUCK
By constructing the tunnel, underground power house and other items,
huge quantity of muck will be generated. It is expected that 30-35 % of
this will be used for making aggregates. The rest will require to be
disposed off and managed in a planned manner.
This is the most important aspect to be dealt with. It is proposed that at
different locations dumping sites will be identified at suitable places.
Retaining walls will be constructed. After the filling is done,
rehabilitation of this site will be done to ensure that neither it flows in
to the water stream nor it poses any other environmental threat.
Plantation, wherever possible, will also be done on these sites so that
these get stabilised over a period of time and do not pose any
environmental problem. When detailed EIA/EMP is done detailed
design for each and every dumping site will have to be prepared.
9.5 REPORT OF SATELLITE DATA ANALYSIS BY NRSA
9.5.1 STUDY BACKGROUND
Central Electricity Authority (CEA) under Ministry of Power, Govt. of
India has earlier identified 399 potential hydroelectric sites in the
country with an installed capacity of 1,07,000 Megawatt (MW). With
a view to preparing an action plan to develop this hydroelectric
potential and prioritizing the implementation of hydro-electric
projects, a Ranking Study was taken up by the CEA in 2001. This
Ranking Study identified 162 most potential sites with a total installed
capacity of 50,560 MW for development.
Preparation of Pre-Feasibility Reports (PFR) of these 162 sites has
been initiated by the CEA in 2002 with works entrusted to a number of
Consultants, namely, National Hydroelectric Power Corporation
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(NHPC), North Eastern Electric Power Corporation (NEEPCO), Water
And Power Consultancy Services India Limited (WAPCOS), Satluj Jal
Vidut Nigam Limited ( SVJNL) , Himachal Pradesh State Electricity
Board ( HPSEB), Uttaranchal Jal Vidut Nigam Limited ( UJVNL) and
Kerala Power Corporation Limited ( KPCL) with time target of
completion of the whole exercise by September 2003. To oversee the
progress of the PFRs preparation in time and with full cooperation of
the Central Government agencies, a Central Coordination Committee
consisting of Central Electricity Authority (CEA), Central Water
Commission (CWC), India Meteorological Department (IMD),
Ministry of Environment & Forest, Survey of India, Geological Survey
of India (GSI) and National Remote Sensing Agency (NRSA) was
constituted by the CEA with Member (Hydro-power) as its Chairman.
The Committee is sitting periodically in presence of the representatives
of the Consultants to take stock of the completion of the studies. One
of the mandates of PFR preparation is “Initial Environmental Study”
with respect to each of the 162 proposed sites using satellite remote
sensing data.
As is well known in India and elsewhere in the world, space
technology plays a very important role in terrain mapping and
scientific assessment of the ground condition at speed, and is ideally
suitable for inaccessible mountainous regions where majority of these
hydroelectric dam/diversion sites are located. Computer processing of
satellite digital data of the dam / diversion sites and their immediate
environ provides wealth of information for preparation of the Pre-
Feasibility Reports. The Potential of this technology was amply
demonstrated in the preliminary ranking study of the 81 proposed
hydro-electric sites in Indus Basin completed by NRSA in October
2001 on behalf of CEA. In view of this, NRSA has been approached
by a number of consultants, namely, NHPC and HPSEB to take up
Initial Environmental Studies in respect of 37 proposed hydro-power
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sites located in the States of Arunachal Pradesh, Himachal Pradesh,
Jammu & Kashmir and Madhya Pradesh using most recent satellite
remote sensing data.
NRSA in the recent month 9 Jan-May 2004) has completed initial
environmental studies with respect to 6 hydro-electric schemes located
in Chenab river basin for HPSEB, Sundernagar. Further, HPSEB has
requested NRSA for similar studies for additional two sites viz.
Chamba and Bajoli holi in Ravi river basin.
This Report deals with Bajoli-Holi hydro-power site.
9.5.2 OBJECTIVE
Principal objective of the satellite based study is to acquire Indian
Remote Sensing satellites (IRS 1C/1D) LISS-III and PAN sensor
digital data of the hydro-power sites and to make quick analysis of
these data in terms of estimation of the submergence area at proposed
Full Reservoir Level (FRL) and mapping of land use - land cover
information within and in immediate surrounding of the proposed
submergence area as inputs for Initial Environmental Study (IES) of
the Pre-Feasibility Report.
The specific objectives and scope of the study are:
• To estimate the area of submergence at proposed FRL of the
proposed hydro-power sites
• To analyse the satellite data for identifying broad landuse -
landcover categories like agricultural land, forest land, barren
land, scrub land, water bodies, settlements, infrastructural features
(roads and bridges) and to estimate the area under each of the
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categories within and in immediate surrounding of the proposed
submergence area at FRL.
9.5.3 SALIENT FEATURES OF THE BAJOLI-HOLI HYDRO-
POWER SITE
Proposed hydro-power site is located at Bajoli-Holi in Ravi River
Basin in Himachal Pradesh falling in Survey of India topo sheets
No.52 D/11. The proposed project scheme at Bajoli-Holi envisages
construction of a diversion structure on Ravi river, and a power house.
The Head-Race Tunnel from the dam to the power house is proposed
to be 15 km in length. The river water will be diverted through the
Head-Race tunnel to the Power House for hydro-power generation.
The geographic location of Dam and Power House for this hydro-
power site is given here :
Dam Power House
Latitude : 32° 16’ 53” N 32° 20’ 31” N
Longitude: 76° 40’ 45”E 76° 32’ 37” E
9.5.4 SATELLITE DATA USED
Indian Remote Sensing Satellite, IRS-IC LISS III and PAN sensors
data of 27th September 2002 covering the study site were procured
from the NRSA Data Centre (NDC) after intensive browsing of the
available satellite data for cloud-free and radiometric suitability. IRS-
1C covers the study site by satellite geo-reference number Path 94 and
Row 48. These data are geometrically and radiometrically corrected
digital data products which can be used readily in Window based
image analysis platform.
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9.5.5 BRIEF METHODOLOGY OF SATELLITE DATA ANALYSIS
Image processing and analysis was done using ERDAS Imagine
image analysis software in Windows platform. Satellite data of IRS
1D LISS III sensor provides 23.5 m spatial resolution and PAN
sensor provides 5.8m spatial resolution. The two sensor data were
geocoded and digitally merged using IHS transformation technique .
Baseline information layers (like rivers/ streams) and infrastructural
features (like roads and bridges), settlements / villages were initially
interpreted on the digital image scene. Subsequently, image
classification technique was performed to obtain the land use-land
cover categories of the study area.
Output maps were composed in the image processing system which
provide the landuse / landcover information along with other
interpreted information such as roads, settlements etc., within the 7
Km radius from the dam site. The location of the diversion structure
and power house from the index map provided by HPSEB,
Sundernagar was superimposed on the satellite data as well as on the
land use - land cover map. Area statistics of different landuse-
landcover categories were generated within the 7 km radius circle
from the diversion point on the river.
9.5.6 OUTPUTS PROVIDED
Based on the analysis of satellite data and other available ancillary
information, the following outputs were generated:
• Map 1 (a) Shows IRS 1 C PAN + LISS III merged satellite image
of 27th September 2002 on 1:50,000 scale covering 7 km radius
from the dam site overlaid with FRL , location of dam site and
power house.
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26
• Map 1(b) Shows satellite derived landuse-landcover map on
1:50,000 scale covering 7 km radius from the dam site overlaid
with FRL , location of dam site and power house. Land use /land
cover map shows the following categories: Forest (Medium and
Low Dense Forest), Agricultural Land, Open Scrub, Barren,
Snow, River Course/ Dry River Bed.
• Map 1(c) Shows the land use- land cover classes and their
corresponding area statistics in hectares within the submergence
area on 1:25000 scale overlaid with FRL, location of dam site and
power house.
• Map 1 (d) Shows the location of the National parks / Wildlife
Sanctuaries vis-à-vis the location of the dam/ Power House and 7
km radius from the location of diversion structure .
• Table.1 Land use-land cover Information within the
Submergence Area ( 11.79 ha.)
S.No Land use-land cover
Category
Area under
submergence (Ha)
% of the total
submergence area
1 High Dense Forest Nil Nil
2. Medium Dense Forest 5.09 43.16
3. Low Dense Forest 0.83 7.04
4. Open Scrub 2.93 24.87
5. Barren / Rock Outcrop 0.21 1.80
6. Agricultural Land Nil Nil
7. Human Settlements Nil Nil
8. River Course including
dry river bed
2.73
23.13
9. Water Bodies Nil Nil
10. Snow Nil Nil
11. Cloud / Shadow Nil Nil
Total 11.79 100.00
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• Table.2 Landuse-landcover Information within the 7 Km
Radius from the Diversion structure at Bajoli Holi
S.No Landuse-landcover Category Total Area
( ha)
% of the total
area
1 High Dense Forest Nil Nil
2 Medium Dense Forest 5640.78 36.65
3 Low Dense Forest 1812.96 11.78
4. Open Scrub 6216.38 40.38
5. Barren 948.69 6.16
6. Agricultural Area 141.45 0.92
7. Human Settlements 3.33 0.02
8. River Course including dry
river bed
105.32
0.68
9. Water Bodies Nil NIl
10. Snow 383.32 2.49
11. Cloud /Shadow 141.77 0.92
Total area 15394.00 100.00
9.5.7. CRITICAL ANALYSIS OF SATELLITE BASED INITIAL
ENVIRONMENTAL STUDY
• Total area under submergence at proposed FRL (2017 m. above
MSL) is estimated to be 11.79 ha (Table.1). The small
submergence area is a positive sign for the development of the
preset hydro-power site.
• It is observed from Table 1 and Figure 1c that the area under
vegetation cover class is estimated to be 5.92 ha. Which constitutes
50% of the total submergence area.
• Forest vegetation is classified as medium dense forest and low
dense forest. Area statistics of the forest density categories are
estimated as 5.09 ha and 0.83 ha respectively. There is no high
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dense forest class is present in the submergence area and its
immediate environs.
• Hence, the presence of forest vegetation cover , which is only to
the extent of 6 ha. will pose least environmental concern in
developing the proposed hydro-power site.
• It is also observed that percent distribution of vegetation cover
class under forest category in the immediate surrounding (7 km
radius circle) of the proposed hydro-power site (table 2) is same (
approx. 50%) as that of submergence area.
• Land areas under other land use categories like barren / rock-
outcrop and open scrub together is around 3.14 ha., which is 32%
of the submergence area. Whereas, it is observed that this category
is predominant (approx. 50%) in the immediate environs of the
proposed hydro-power site (Table 2).
• It is found that there is no agricultural land present within the
proposed submergence area. This is a welcome positive indicator
of insignificant environmental cost, should the proposed hydro-
power project is developed at this site.
• There are no surface water bodies other than the river course.
• It is observed that there are no settlements existing within the
submergence area. This is a positive indicator so far as socio-
economic and demographic factor is concerned with respect to the
proposed hydro-power development project.
• It is observed from the Table 2 that snow cover is present to an
extent of 383 ha in the 7 km radius circle of the proposed dam with
few isolated settlements and few agricultural lands.
• In the absence of available information from other sources about
the existence and spatial extent of national parks and wildlife
sanctuaries, best efforts were made to collect information from the
Internet. The information available in website of United Nations
Environment programme World Conservation Monitoring Center
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(http://www.unep-wcmc.org), National Informatics Centre, www.
wildarunachal.org and www.arunachalbhawan.com regarding
Arunachal Pradesh State and its National Parks / Wildlife
Sanctuaries, were browsed through. Based on these Internet
websites, following information is gathered.
- Great Himalayan National Park with an areal extent of 62,000 ha is
the only nearest National park (Fig 1(d)) is located at 83 km away
from the dam site in south eastern direction. However, exact
boundary / shape of this National Park is not available from these
websites. It is unlikely to have any significant impact on Great
Himalayan National Park. The Fig. 1d also shows that there are ten
sanctuaries located around the proposed dam site within 90 km
radius, of which Kugti, manali and Kais are located within 50 km
distance from the proposed dam site, whose areal extents are
37,886 ha, 3180 ha, 1419 ha respectively.
- Though the exact boundaries are not available , since Kugti
sanctuary is close to the proposed site (26 km away from the dam
site), it may likely to have impact on it. Hence, a detailed impact
assessment and habitat analysis may be carried out. However, exact
spatial extent (boundaries) of this park may be superimposed for
verifying the likely impact.
- Similarly, Manali sanctuary and kais sanctuary are situated at an
aerial distance of 42 and 54 kms from the dam site and their spatial
extents are 3180 ha and 1914 ha. which are unlikely to have any
impact by the proposed hydro electric scheme..
- Since 7 Km radius around the dam site was considered as the area
of study, efforts were made to check whether the geo-coordinates
of this National Park/ Wildlife Sanctuary is falling within the area
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of study. The map No. 1(d) explains the location of the sanctuary
vis-à-vis the dam site and the power house.
9.5.8 CONCLUSION & RECOMMENDATION
1. Satellite based study has provided insight into the land use-land
cover pattern and their spatial extent within the submergence area
at FRL (2017m. above MSL) and within the 7 Km radius vicinity
of the proposed dam site. Such detail information on a scale of
1:25,000 is not available from any other sources at present.
2. It is observed that, there are no settlements within the submergence
area. This is a positive indicator of this hydro-power site. Within
the 7 Km radius of the dam site, there are small pockets of human
settlement (3.33 ha). However, Socio-economic and demographic
data of this and others not identified need to be verified on the
ground.
3. There is no agricultural land within submergence area. The
environmental cost on this score therefore is absolutely nil.
4. The proposed dam site and the power house locale is endowed with
good medium dense forest vegetation. However, since the
submergence area at FRL is confined within the river gorge, forest
vegetation of the spatial extent of 5.92 hectares will be affected due
to submergence. This is very insignificant. Species types of these
forest vegetation need to be identified from local Forest
Department and by field visit to the area.
5. Since the proposed dam is located on the gorge, the submergence
area mostly confines to the river course. The river course including
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the dry river bed constitutes 23% of the proposed submergence
area (11.79 ha.).
6. Kugti, Manali and Kais sanctuaries are situated at an aerial distance
of 26, 42 and 54 kms respectively, away from the proposed dam
site, according to the information collected from several websites.
The location and wildlife of these sanctuaries will in no way be
affected by the hydro-electric project, since the fetch distance of
the reservoir submergence is around 0.6 km only. However, since
Kugti sanctuary is only 20 km away from the dam site, whose
exact spatial distribution need to be ascertained for evaluating the
impact by the proposed scheme.
7. Great Himalayan National park, which is located 83 km away
from the dam site. Though, the exact boundary / shape of this
National Park is not available from these websites, the present
hydro electric scheme with less ponding area and small fetch
distance, is unlikely to have any significant impact on this National
Park directly.
IX -
32
IX -
33
PARA DESCRIPTION PAGE
9.0 DESCRIPTION OF THE PROJECT IX-I
9.1 DESCRIPTION OF ENVIRONMENT IX-I TO IX-9
9.2 BASE LINE ENVIRONMENTAL STATUS IX-9 TO IX-12
9.3 ENVIRONMENT IMPACT ASSESMENT AND
EVALUATION
IX-12 TO IX-15
9.4 PREDICTION OF IMPACTS IX-15 TO IX-21
9.5 REPORT OF SATELLITE DATA ANALYSIS BY
NRSA
IX-21 TO IX-31
PLATE 9.1 IRS 1C PAN +LISS III MERGED SATELLITE
IMAGE OF 27TH SEPT. 2002
IX-32
PLATE 9.2 LANDUSE- LAND COVER MAP SHOWING THE
SURROUNDINGS OF PROPOSED DIVERSION
SITE AT BAJOLI-HOLI
IX-33
PLATE 9.3 MAP OF NATIONAL PARKS/ SANCTUARIES
AND THE LOCATION OF BAJOLI-HOLI
HYDROPOWER SITE AND 7 KM RADIUS
CIRCLE FROM DIVERSION SITE
IX-34
PLATE 9.4 SATELITE DERIVED LAND USE – LAND
COVER MAP OF PROPOSED DIVERSION SITE
AND ITS SURROUNDINGS
IX-35
IX -
34
CHAPTER – X INFRASTRUCTURE
10.0 IDENTIFICATION OF THE BROAD INFRASTRUCTURAL
REQUIREMENT FOR IMPLEMENTATION OF THE PROJECT
Bajoli-Holi Hydel Project is situated in Chamba Distt. of Himachal
Pradesh. The diversion barrage is about 22 km. from village Holi and 102
Km from Chamba, which is approachable through all weather road up to
Naya Gaon by state highway. Power House site is approachable by RCC
bridge on river Ravi near village Holi.
Adequate provision for residential and non-residential accommodation with
necessary amenities has been made for construction and design staff
proposed for the project. Workshop, stores, POL pumps, explosive
magazine and other infrastructural facilities have also been provided in the
estimate. Necessary provision for telecommunication, medical , educational
facilities and safety /security measures have also been made in the report.
All infrastructure facilities proposed for this project have been shown in
Drg. No. Bajoli-Holi-PR-12.
10.1 ROADS
10.1.1 GENERAL
A total of about 17 km. length of (5/7m. wide) road shall be needed to
connect the existing motorable road with the various project components
and job facilities. The widening of existing roads in the total length of 10
kms. has also been proposed.
10.1.2 PROJECT ROADS
Approach road 5/7 m. wide, 17 Km. long will connect different work sites
of the project with the existing motorable road.
The following roads have been proposed.
1. Proposed road to barrage site, = 3.00 km.
2. Surge shaft, pressure shaft and power house = 5.00 km
3. Proposed road to adit of HRT = 9.00 km
Total = 17.00 km.
4. Widening of existing motorable road from
Holi to Naya Gaon (Bajoli) to diversion site) = 10.00 km.
Total = 10.00 km.
5. Provision of R..C.C. bridge on river Ravi
near power house site = 1 No.
Provision of suspension bridge = 2 No.
10.2 BUILDINGS
It is proposed to construct residential and non-residential colonies for this
project at village Naya Gaon in private land/Govt. land. The existing HPSEB
workshop, offices and other buildings at Holi will also be available for use in
this project.
10.2.1 COLONY AT SUNDERNAGAR
A permanent residential/non-residential complex for design organization
will be constructed at Sundernagar. The same can be used for
monitoring/planning liaison purpose after the completion of the project.
10.2.2 COLONY AT VILLAGE NAYA GAON
Residential / non-residential colony for the construction of the project is
proposed to be constructed at village Naya Gaon which is about 15 km
from Holi and 7.00 km. from diversion barrage. Labour huts , stores and
field offices will be constructed near the project components on the small
terraces available.
10.2.3 OFFICE COMPLEX FOR OUTLET SIDE WORKS
Office complex for the construction of power house complex, penstock, surge
shaft and tunnel from outlet end is proposed on the terrace available near
village Holi.
10.2.4 SCHOOL & HOSPITAL
Adequate provision of buildings for Hospital, school etc. has been made in the
project estimate under Sub-Head K-buildings to cater for construction force.
First aid posts shall be provided at all project sites.
10.2.5 FIELD HOSTEL & REST HOUSE
Field hostel is constructed in the Holi project area near residential colony be
upgraded.
10.3 DUMP AREA
The muck of open & underground excavation shall be dumped in dump areas
identified at each project component site. The dumping station for power
house muck may be proposed at 1.0 km upstream from power house. Dump
areas chosen are located much above the river/nallah banks and are provided
with suitable retaining walls etc. Bull dozers shall be deployed in dump areas
for spreading and compaction of dumped material.
10.4 JOB FACILTIES
Flat terraces available near the project components wherever possible shall be
utilized for job facilities like stacking of construction material, D.G. sets, truck,
trailers, cement carriers, road rollers and site office stores etc.
10.5 QUARRY SITES
The material in the river bed may be suitable for aggregate. Rock from
different quarries in the vicinity of the project will also be tested, to assess
their suitability for manufacturing aggregate.
10.6 TELECOMMUNICATION
10.6.1 INTERNAL TELEPHONE SYSTEM
It is proposed to have an independent telephone exchange for this project. All
important work sites, offices within the project area will be connected by
telephones. A 80-lines capacity private automatic exchange (PBX) for the
project will be provided .
10.6.2 EXTERNAL TELEPHONE SYSTEM
Telecommunication link between project sites and outside places will be
provided by existing communication net work of Post & Telegraph
Department connected to the nearest P&T exchange at Holi. This system
would be operated and maintained by P&T Department on rental basis.
Power Line Communication Carrier (PLCC) system is also proposed for the
project.
10.7 WIRELESS SYSTEM
On the pattern of other ongoing hydel projects in H.P., fixed type VHF
Wireless link is proposed to be provided between project sites and design
office at Sundernagar, which will be further connected to existing wireless
system of HPSEB at Shimla.
10.8 PLANT AREAS
Plant area for different sites of work have been provided near respective sites.
It is proposed to install a central aggregate crushing, processing and
classification plant near quarry site proposed at power house site which will
fulfill the requirements of aggregates for diversion barrage, intake works and
powerhouse site to cater for the requirements of works of HRT from outlet
end, surge shaft, pressure shaft and powerhouse and appurtenant works. An
adequate capacity batching and mixing plant will be installed near intake to
cater the requirements of concrete for all inlet side works including tunnel
lining. Other batching and mixing plants of requisite capacity will be provided
near power house site for concreting work in power house complex , pressure
shaft, head race tunnel and surge shaft.
Central compressor houses will be located near tunnel portal to meet up the
requirements of the compressed air.
10.9 FIELD WORKSHOP
The HPSEB workshop be proposed at Holi will be utilized for this project on
job order basis. More workshops/repair shops are proposed to be established
near diversion site & power house site.
10.10 CONSTRUCTION POWER
Requirement of construction power will be met from existing transmission net
work in the area by suitably augmenting the same to meet requirement of the
project at various sites. Necessary provision for providing power lines and
distribution system has been made in the project estimate.
Adequate provision for stand by diesel generating sets has been made in the
project estimate to meet up power requirements in the event of power failures,
shutdowns / breakdown.
10.11 SAFETY
Safety is an essential job requirement for a highly mechanized work set up.
Adequate provision for fire fighting arrangements and security arrangements
has been made in the project estimate by way of police post/check-post and
check barriers etc.
Adequate safety/preventive measures against accidents are proposed to be
taken in accordance with the following Indian Standard Codes:
IS: 4756 For safety in tunneling work.
IS 3996 For scaffolds and ladders.
(Part I&II)
IS: 3764 For excavation work.
IS: 4081 For blasting and related drilling operations.
IS: 4138 For working in compressed air.
PARA DESCRIPTION PAGE
10.0 IDENTIFICATION OF THE BROAD
INFRASTRUCTURAL REQUIREMENT FOR
IMPLEMENTATION OF PROJECT
X-1
10.1 ROADS X-1
10.1.1 GENERAL X-1
10.1.2 PROJECT ROADS X-2
10.2 BUILDINGS X-2
10.2.1 COLONY AT SUNDERNAGAR X-2
10.2.2 COLONY AT VILLAGE NAYA GAON X-3
10.2.3 OFFICE COMPLEX FOR OUTLET SIDE WORKS X-3
10.2.4 SCHOOL & HOSPITAL X-3
10.2.5 FIELD HOSTEL AND REST HOUSE X-3
10.3 DUMP AREA X-3
10.4 JOB FACILITIES X-4
10.5 QUARRY SITES X-4
10.6 TELECOMMUNICATION X-4
10.6.1 INTERNAL TELEPHONE SYSTEM X-4
10.6.2 EXTERNAL TELEPHONE SYSTEM X-4
10.7 WIRELESS SYSTEM X-5
10.8 PLANT AREA X-5
10.9 FIELD WORKSHOP X-5
10.10 CONSTRUCTION POWER X-6
10.11 SAFETY X-6
CHAPTER – XI CONSTRUCTION PLANNING & SCHEDULE
11.0 CONSTRUCTION PLANNING & SCHEDULE
11.1 GENERAL APPROACH FOR CONSTRUCTION PLANNING AND
EXECUTION OF PROJECT COMPONENTS
11.1.1 CONSTRUCTION METHODOLOGY & EQUIPMENT PLANNING
11.1.2 GENERAL
Bajoli-Holi Hydel Project is a 180 MW capacity run of the river scheme in
Chamba District of H.P envisages utilization of 71.74 cumecs of design
discharge and 308 m of gross head. Diversion barrage has been proposed
at about 22 km. u/s of Holi village and the power house at about 1.00 km
d/s of Holi village. The project comprises following main civil structures:
Diversion Barrage
Intake structure
Desanding basin
Head Race Tunnel
Surge Shaft
Pressure Shaft
Power House
Tail race tunnel
11.1.3 COMPLETION TIME AND AVAILABLE WORKING SEASON
Construction programme, selection of methodology and equipment have
been planned with the aim of commissioning of the project in four and
half years. Available working season in a year shall be of 12 months for all
works, and eight months for the works in the river bed.
XI - 2
11.1.4 APPROACH ROAD AND THE LOCATION OF THE PROJECT
A total of about 17 Km road (5/7 m wide) shall be needed to connect the
existing motorable road with the project components i.e. barrage,HRT,
surge shaft area, power house, colony area, dump areas and other facilities.
11.1.5 CONSTRUCTION MATERIAL
11.1.5.1 CEMENT
ACC cement factory located at Barmana in Distt. Bilaspur (HP), on NH-
21 and at a distance of 415 Kms from the project site shall be the main
source of cement for meeting the entire cement requirement of the project.
Bagged cement shall be transported in trucks and stored in project stores at
different sites.
11.1.5.2 STEEL
SAIL stockyard at Jalandhar, 315 Kms. from main project store, shall be
the main source of structural and reinforcement/ tor. steel. Sizeable
quantities of reinforcement steel and structural steel shall have to be
stocked and replenished regularly. Penstock steel plates if not available
indigenously however, may have to be imported to suit the design
specifications.
11.1.5.3 AGGREGATE
The material in the river bed may be suitable for aggregate, however, the
same has to be got tested at detailed investigation stage.
Rock from different quarries in the vicinity of the project may also be got
identified, to assess their suitability for manufacturing aggregate. Rock
extracted from the quarries as well as from tunnel will be crushed and
classified to various sizes of aggregate in batching and mixing plant one
XI - 3
near the intake site and other near power house ( for excavated material
from tunnel).
11.1.6 STORES, LUBRICATION & WORK SHOP
The Petrol/diesel pumps, explosives magazine, workshops and other
construction facilities shall be provided to facilitate execution of the
project. While central stores for storage of cement, T&P articles, steel yard
as well as timber yard and main workshop shall be provided . Site stores
and field workshops will be established near respective sites. Petrol/diesel
pump shall be established near the power house site.
11.1.7 AGGREGATE PROCESSING PLANTS
Two aggregate crushing classification and sand manufacturing plants shall
be installed near each site of work and 2 nos. batching and mixing plants
shall be located near Power house& Diversion site.
11.1.8 PLANT AREAS
Plant areas for locating air compressor house, cement, aggregate, T&P,
stores and water storage tanks etc., shall be located near each site of work
and 2 nos. batching and mixing plants shall be located near Power house &
diversion site.
11.1.9 DUMP AREAS
The muck of underground excavation shall be dumped in dump areas
located within 1 km to 3.0 km from each portal. Dump areas for surface
excavation in surge shaft shall be at a maximum distance of 1 km and
power house area at a distance of 1.50 km.. Dump areas chosen are located
much above the river/nallah banks and are provided with suitable retaining
XI - 4
walls etc. Bull dozers shall be deployed in dump areas for spreading and
compaction of dumped material.
11.1.10 PRE-CONSTRUCTION FACILITIES
Pre construction facilities such as land acquisition for labour huts, plant
areas, stores, residential and non residential buildings, approach roads,
construction of bridges and explosive magazine in the valley shall be made
available to facilitate construction of the project.
11.1.11 EQUIPMENT PROVISION
Since main works of the project are proposed to be executed on contract
basis except the required infrastructural facilities, as such, the necessary
provision of machinery like material trucks, trailors, cement carriers, motor
grader and road rollers etc. has been made under Q-special-T&P, for
carrying out the works of infrastructural facilities. Provisions for personal
carriers, ambulance and field workshop equipment have also been made
under project estimate.
11.2 CONSTRUCTION SCHEDULE
The project has been proposed to be completed in 4½ years. Method of
execution of various components and selection of equipments have been
done with the object of commissioning first hydro unit by the end of 3rd
month of the fifth year, the second unit by the end of 5th month of fifth year
and the third unit by the end of 6th month of fifth year.
11.2.1 INFRASTRUCTURAL WORKS
It is proposed that all infrastructural works on the project comprising roads,
buildings, adits, workshops, stores, utility works, surveys, development of
XI - 5
quarries, leveling of area for installation of equipment and plants, pre-
qualification of tenders, award of contracts, detailed design of components
and other preliminary works shall be continued up to 4th year of project
execution.
11.2.2 DIVERSION BARRAGE
i) Coffer dam:- During 8th month of project construction.
ii) Excavation of barrage Const. Ist stage
From 9th month to 15th month of project construction.
iii) Concreting of barrage Ist stage
From 12th month to 15nd month.
From 18th month to 22nd month.
iv) Coffer dam 2nd stage
During 18th month.
v) Excavation of barrage 2nd stage
From 19th month to 25th month.
vi) Concreting of barrage 2nd stage
From 24th month to 27th month.
From 30th month to 36th month.
11.2.3 INTAKE STRUCTURE & FEEDER TUNNELS
Excavation:- From 9th month to 15th month.
Concreting:- From 18th month to 27th .
11.2.4 DESILTING TANK
Excavation:- From 9th month to 24th month.
Concreting:- From 21th month to 33rd month.
11.2.5 MECHANICAL WORKS FOR THE ABOVE FEATURES
XI - 6
From 20th to 45th months.
11.2.6 HEAD RACE TUNNEL
Excavation:- From 7th month to 36th month.
Concreting:- From 21st month to 46th month.
Grouting & cleanup :- From 42nd month to 48th month
11.2.7 SURGE SHAFT
Excavation from 12th month to 24th month.
Concreting:- From 24th month to 35th month.
Grouting & Clean up:- From 35th month to 38th month.
11.2.8 PRESSURE SHAFT
Excavation:- From 15th month to 27th month.
Concreting& liner:- From 27th month to 39th months.
11.2.6 POWER HOUSE
Excavation:- From 12th month to 27th month.
Concreting:- From 21st month to 42nd months.
11.2.10 TAIL RACE TUNNEL
Excavation:- From 19th month to 25th month. ; Concreting:- In 41st month.
11.2.8 INSTALLATION, TESTING AND COMMISSIONING
Installation of hydro units shall be started from the 32nd month. A period of
3 months for testing and commissioning of each unit has been provided
with first unit proposed to be commissioned in 51st month and second unit
XI - 7
in 53rd month of construction and 3rd unit in 54th month thus completing
the construction of the project as a whole in 54 month duration.
XI - 8
PARA DESCRIPTION PAGE
11.0 CONSTRUCTION PLANNING & SCHEDULE XI-1
11.1 GENERAL APPROACH FOR CONSTRUCTION PLANNING AND
EXECUTION OF PROJECT COMPONENTS
XI- 1
11.1.1 CONSTRUCTION METHODOLOGY & EQUIPMENT PLANNING XI-1
11.1.2 GENERAL XI-1
11.1.3 COMPLETION TIME AND AVAILABLE WORKING SEASON XI-1
11.1.4 APPROACH ROAD AND THE LOCATION OF THE PROJECT XI- 2
11.1.5 CONSTRUCTION MATERIAL XI- 2
11.1.5.1 CEMENT XI- 2
11.1.5.2 STEEL XI-2
11.1.5.3 AGGREGATE XI- 2 TO XI-3
11.1.6 STORES, LUBRICATION& WORK SHOP XI- 3
11.1.7 AGGREGATE PROCESSING PLANTS. XI- 3
11.1.8 PLANT AREAS XI-3
11.1.9 DUMP AREAS XI-3 TO XI-4
11.1.10 PRE-CONSTRUCTION FACILITIES XI-4
11.1.11 EQUIPMENT PROVISION XI- 4
11.2 CONSTRUCTION SCHEDULE XI- 4
11.2.1 INFRASTRUCTURAL WORKS XI-4 TO XI-5
11.2.2 DIVERSION BARRAGE XI-5
11.2.3 INTAKE STRUCTURE AND FEEDER TUNNEL XI-5
11.2.4 DESILTING TANK XI-5
11.2.5 MECHANICAL WORKS FOR THE ABOVE FEATURES XI-5
11.2.6 HEAD RACE TUNNEL XI-6
11.2.7 SURGE SHAFT XI- 6
11.2.8 PRESSURE SHAFT XI-6
11.2.9 POWER HOUSE XI-6
11.2.10 TAIL RACE TUNNEL XI-6
11.2.11 INSTALLATION TESTING AND COMMISSIONING XI-6
XI - 9
CHAPTER – XII
COST ESTIMATE
12.0 GENERAL
12.1 BASIS OF ESTIMATE
The estimate of Unit-I Civil Works has been prepared to arrive at the
capital cost of the Chamba Hydro Electric Project basis of June., 2004
price level. It is presumed that major civil works will be executed on
contract basis. The cost estimate does not include following items:-
- Escalation after June, 2004
- Interest during construction.
Detailed estimate of cost for Unit-I civil works is based mainly upon
various designs/drawings finalized for appurtenant structures and the rates
for principal items of works as per guide lines furnished by CEA vide
letter dt. 24th Oct. 2003. A provision of 3% has been made for
contingencies for C-works under Unit-I works. Guidelines for preparation
of project estimate issued by CWC during March, 1997 have been
generally followed for formulation of the estimate.
12.2 DESCRIPTION OF ITEMS
12.2.1 UNIT-I CIVIL WORKS
Under the head, civil works provision as made for various components of
the project is detailed here under:
A-Preliminary
Under this sub-head, provision of Rs. 958.55 lac has been made for
surveys and investigations conducted or to be conducted to arrive at the
optimum designs of project components.
B- Land
This covers the provision for acquisition of land for construction of the
project components, colonies, offices and store complexes and
compensation for trees and standing crops. Provision for forest trees in the
project area has also been included. A provision for Rs. 797.38 lac has
been made under this sub-head.
J Power Plant civil works
This covers the cost of civil engineering structures comprising intake
structure, head race tunnel, surge shaft, pressure shaft/ surge shaft, surface
power house complex and tail race channel. The total cost works to be Rs.
13365.95 lac.
K- Buildings
Buildings both residential and non- residential have been grouped
separately under permanent and temporary categories Under the
permanent categories, all those buildings have been included which will
be subsequently utilized for the operation and maintenance of project.
Whereas, under the temporary category, credit to the extent of 15% has
been given to the project on account of resale thereof. The cost has been
worked out on basis of plinth area rates as notified by HPPWD.. A
provision of Rs.1378.14 lac has been made under this sub-head.
X-Environment & Ecology
A provision of Rs. 502 lac has been made under this sub-head for
maintaining and improving the environmental status of the project area
and fir afforestation of affected area.
II-Establishment
A provision under this head has been made for Rs. 1468.68 lac @ 8% of I-
Works.
V-Receipts & Recoveries
This provision covers estimated recoveries by way of resale or transfer of
special T&P and temporary buildings. The amount thus works out to Rs.
293.02 lac only.
M-Plantation
This covers the cost of plantation and protection of plants to be planted
along project roads, colonies and in project area. Accordingly a provision
of 25.00 lac has been made under this sub-head.
O- Miscellaneous
A provision of Rs. 995.70 lac has been made for meeting cost of various
items listed therein.
Q-Special T&P
As the major civil works have been proposed to be got done on contract
basis. Machinery required for departmental activities like infrastructural
works, there subsequent repair/ maintenance and supervision works has
mainly been included under this sub-head. A provision of Rs. 496.71 lac
has been made under this sub-head.
R-Communication
A provision of Rs. 429.40 lac under this sub-head covers the cost of
roads. The road width have been planned to cater to the anticipated traffic
including movement of heavy trailors. Cost of roads is based on the rates
as notified by State HPPWD .
Thus a provision of Rs. 22481.73 Lac. has been made to cover the costs
under this unit (civil works)
12.2.2 UNIT-III ELECTRICAL WORKS
12.2.2.1 P-PRODUCTION
Cost of generating plants and equipments is based on current budgetory
prices. Prices of auxiliary equipments and services are based on historical
prices. Excise duty has been considered @ 16% of the component. CST,
Insurance and transport to site has been taken @ 6% of the cost of
respective component. Erection and commissioning charges have also
been taken @ 10% as per experience gained on similar installations in the
state. A provision of Rs. 14131.38 lacs has been made to cover the costs
under this sub-head.
12.2.2.2 T-TRANSMISSION
The cost based on detailed analysis on actual requirement under this sub
head amounts to Rs. 1178.47 lacs.
12.3 DETAILED ESTIMATE OF COST
Detailed estimate of cost as explained in above paras is given in
succeeding paras :
PARA DESCRIPTION PAGE
12.0 GENERAL XII-1
12.1 BASIS OF THE ESTIMATE XII-1
12.2 DESCRIPTION OF ITEMS XII-1
12.2.1 UNIT-I CIVIL WORKS XII-1 TO XII-4
12.2.2 UNIT-III ELECTRICAL WORKS XII-4
12.2.2.1 P-PRODUCTION XII-4
12.2.2.2 T-TRANSMISSION XII-5
12.3 DETAILED ESTIMATE OF COST XII-5 TO XII-36
CHAPTER-XIII
ECONOMIC EVALUATION
13.0 GENERAL
Bajoli-Holi Hydro-electric Project has been contemplated as a run of the
river development on Ravi river in tribal areas of Chamba district of
Himachal Pradesh. This project is estimated to cost Rs. 616.64 Cr. at price
level of June, 2004. The cost at power bus bar worksout to Rs. 580.62 Cr.
Abstract of cost estimate of Civil works, P-Production and T-Transmission
have been given as per Annexure13.1-(a) to13.1-(c). Year wise phasing of
expenditure for capital required on this project is given as per Annexure-
13.2. Interest during construction has been considered as per Annexure-
13.3. Depreciation on Civil and Electrical works has been worked out as
3.00% as per Annexure-13.4.The levelised tariff of energy generated at
power house bus bars has been worked out as Rs. 1.60 per unit during 90%
dependable year as per Annexure-13.5. The cost of energy in the Ist year of
operation works out to Rs. 2.03 per unit.
13.1 CAPITAL COST OF THE PROJECT
Abstract of the capital cost of the project, to the price level of June, 2004 is
as under: -
XIII - 2
S.No. Description Amount
(Rs. in lac.)
1. Unit-I Civil works 41501.13
2. P-Production (Electrical works) 16560.59
Total Generation Cost 58061.72
3. Transmission 3602.54
Grand total 61664.26
13.2 ECONOMIC JUSTIFICATION
Bajoli-Holi HEP has been conceived as an upstream development of Kutehr
HEP (260MW) and power therefrom is has been proposed to evacuated
through 400 KV D/C line up to PGCIL substations in the Northern grid
As laid down in CEA and CERC Guidelines, economic justification of a
hydel project is to be done by comparing cost of alternative sources of
energy in that region. The levellized tariff of this project in 90% dependable
year works out as Rs. 1.60/ unit at power house bus bars as per Annex.-
13.5.This project will provide power at cheaper rates in comparison to
thermal power, rate which , at present is more than Rs.3.75 / unit.
Additionally this project will provide pollution free power for years together
at much cheaper rates considering the escalation in coal prices for Thermal
Power.
13.3 CAPITAL STRUCTURE
Capital structure has been assumed as 70% debt from Financial Institutions
and 30% equity from Govt.
XIII - 3
13.4 REVENUE ANTICIPATION
Power tariff for supply of power at powerhouse bus bars has been assumed
as Rs. 2.75 per unit. Revenue has been assessed accordingly for 90%
dependable year as Rs. 199.3 Cr.
13.5 REPAYMENT PERIOD
Normally, the leading financial institutions in India prescribe a repayment
period of 15 years including 3 to 4 years moratorium period. A period of 12
years has therefore been taken into account, as repayment period in fixation
of tariff.
.
13.6 COST PER MW
The estimated cost of the project at June, 2004 price level is Rs. 616.64 Cr.
including transmission and Rs. 580.62 Cr. at power bus bar for an installed
capacity of 180 MW. This gives a capital cost of Rs. 3.43 Cr.per MW of
installed capacity including cost of transmission and Rs. 3.23 Cr. per MW
for generation. At present price level, the cost of medium hydro-electric
project at Rs. 6.00 crore per MW is considered to be reasonable. From this
criterion, the cost per MW for Bajoli - Holi Hydel Project is reasonable
making the project suitable for exploitation.
13.7 INTEREST DURING CONSTRUCTION
The detail of expenditure during the construction period and the calculation
of interest during construction have been shown in Annexure-13.3. It is
seen that IDC @ 10.00 % on loan works out to Rs. 68.60 crores at power
house bus bars.
XIII - 4
13.8 ENERGY AVAILABLE FOR SALE
As per power studies of the project, the total energy generation in 90%
dependable year has been arrived at 724.83 MUs. As per Govt. of India
Guide Lines, an auxiliary consumption @ 0.7% and transformation losses
@ 0.5% have been considered at power house bus bars .
13.9 RATE OF DEPRECIATION
As per the revised guidelines circulated by Govt. of India, Ministry of
Power, Vide notification dated 29th March, 1994, the weighted rate of
depreciation has been worked out on the basis of straight line formula. The
rate of depreciation works out to 3.00% of the project cost as per
Annexure-13.4.
13.10 OPERATION AND MAINTENANCE CHARGES
As per the guide lines of Ministry of Power, Govt. of India, the Operation
and Maintenance charges inclusive of insurance have been taken as 1.50 %
of the capital cost.
13.11 CALCULATION OF TARIFF
Calculation of tariff for primary energy during 35 years of operation for
90% dependable year has been worked out as per GOI notification shown in
Annexure-13.5 comprising the following.
i) Interest on loan from PFC @ 10.00 % p.a.
XIII - 5
ii) Interest on working capital @ 9.75 % required for 2 months of
average billing for sale of electricity and operation and maintenance
expenses for one month.
iii) O&M charges including insurance charges @ 1.5% p.a.
iv) Income tax @ 35% and surcharge @ 10% on income tax has been
considered.
v) Discounting rate @ 12% for tariff calculation .
At power house bus bar, it will be seen that sale rate of power shall be Rs.
2.03 per unit during Ist year of operation and Rs. 0.97 per unit during 13th
year i.e after repayment of loan. The levelised tariff rate works out to Rs.
1.60 per unit at power house bus bars.
13.12 INDIRECT BENEFITS
Beside providing pollution free power at a cheaper rate to the Northern
Grid; discussed as in preceding paras, this project, located in tribal areas of
Chamba district of HP, will help in the overall development of the people of
the area.. Employment to skilled/non-skilled labour of the area, industrial
and economic development are additional benefits from this project.
Keeping these points in view, this project merits consideration for an early
implementation.
13.13 MERITS OF THE PROJECT
Bajoli - Holi HEP (180 MW) is an up stream development of proposed
Kutehr HEP (260 MW). Following are the strengths and weaknesses of the
project.
i) Project sites are located on the right bank of river Ravi.
XIII - 6
ii) No major resettlement of people is required for construction of
project.
iii) Construction material will be locally available.
iv) Almost all the major sites of the project viz. intake, inlet portal and
adit portals of HRT and power house will be connected with
motorable road.
v) The levellised tariff works out to be Rs. 1.60 per unit at power
house bus bar which is on lower side.
13.14 CONSTRUCTION SCHEDULE
The construction of the project has been proposed to be completed in four
and half years period. The construction schedule has been presented in
drawing No. Bajoli - Holi-PR-11 .
XIII - 7
XIII - 8
PARA DESCRIPTION PAGE
13.0 GENERAL XIII-1
13.1 CAPITAL COST OF THE PROJECT XIII-1 TO XIII-2
13.2 ECONOMIC JUSTIFICATION XIII-2
13.3 CAPITAL STRUCTURE XIII-2
13.4 REVENUE ANTICIPATION XIII-3
13.5 REPAYMENT PERIOD XIII-3
13.6 COST PER MW XIII-3
13.7 INTEREST DURING CONSTRUCTION XIII-3
13.8 ENERGY AVAILABLE FOR SALE XIII-4
13.9 RATE OF DEPRECIATION XIII-4
13.10 OPERATION AND MAINTENANCE
CHARGES
XIII-4
13.11 CALCULATION OF TARIFF XIII-4 TO XIII-5
13.12 INDIRECT BENEFIT XIII-5
13.13 MERITS OF THE PROJECT XIII-5 TO XIII-6
13.14 CONSTRUCTION SCHEDULE XIII-6
ANNEXURE-13.1-(a)
TO 13.1(c)
ABSTRACT OF COST OF CIVIL
WORKS, P-PRODUCTION & T-
TRANSMISSION
XIII-7 TO XIII-9
ANNEXURE-13.2 YEARWISE PHASING OF FUNDS XIII-10
ANNEXURE-13.3 CALCULATION OF INTEREST DURING
CONSTRUCTION AT POWER HOUSE
BUS BARS
XIII-11
ANNEXURE-13.4 WEIGHTED AVERAGE DEPRECIATION
XIII-12
ANNEXURE-13.5 LEVELLISED TARIFF OF ENERGY FOR
90% DEPENDABLE YEAR AT POWER
XIII-13 TO XIII-
14
XIII - 9
HOUSE BUS BARS.
EXECUTIVE SUMMARY
1. INTRODUCTION
As a part of an exercise to assess the balance hydro potential of the
country Central Electricity Authority (CEA )identified more than
399 Hydro-electric Projects with probable installed capacity of 50,000
MW. After carrying out ranking studies, 162 projects have been
identified for preparation of Preliminary Feasibility Reports. Bajoli
Holi in Ravi basin has been identified as one of these projects for
preparation of PFR by HPSEB so that it could be taken up for further
development during the 10th & 11th Plans. Bajoli Holi HEP is
located in Ravi basin between the longitude 76°40'45" - 76°32'37" and
latitude 32°16'53" to 32°20'31" in the Chamba district of Himachal
Pradesh.
Consequently site visits were made to the area by Engineers of
HPSEB and Geologists of GSI for identification/selection of suitable
site. The diversion site of the project is located near village Bajoli
and underground power house site is located near village Borola
(Opposite to village Holi) on Chamba-Holi road and all sites of the
project will be well connected with roads.
2. SCOPE OF THE PROJECT
The project has been contemplated as an upstream development of
Kutehr HEP (260 MW). It envisages the construction of barrage
across the river Ravi near village Bajoli, intake structure, two no.
feeder tunnels and underground desilting arrangement to divert
71.74 cumecs of water through a 5 m dia modified horse shoe
concrete lined tunnel 14600 long, a surge shaft 12 m dia ± 96 m
heigh, a pressure shaft 4 m dia trifurcating near power house to 2.30
m dia each to generate 180 MW power in an underground power
house near village Barola. The annual power generation from the
project in 90% dependable year will be 762.98 Gwh.
3. HYDROLOGY
River Ravi originates from Bara Banghal in Kangra district as a joint
stream formed by the glacier fed Bhadal & Tantgari at an elevation
of 4229 m above mean sea level. High peaks of the catchment remain
covered with snow for about 9 months in a year. The catchment
area of Bajoli Holi diversion site measures 760 Sq.Km. The entire
catchment comprises of mountainous terrain with steep hill slopes.
Out of total catchment area of 760 Sq.km., about 30% area is under
permanent cover of snow. The principal tributaries of the Ravi upto
Bajoli Holi diversion site are Tanetar Gol nallah and Sandrali nallah,
Dera nallah and Raula ka nallah. The project area receives
precipitation due to the South-West Monsoon as well as the
Western disturbances that pass over the North–West part of the
country during winter. There are thirteen non recording type rain
gauge station in the catchment area of the river Ravi. The normal
annual rainfall and annual rainfall has been recorded in millimeters
at all these stations for the period 1960 to 2000 by the office of
Director land records, revenue department (HP). The river run off
has been derived from melting of the snow/ice/glacier bound area
of the catchment and the other which is directly derived from
rainfall. Discharge data is available for hydrological studies at
Bagga, Durgathi, Banthu, Tiyari and Kutehr. The design discharge
of 71.74 cumecs has been proposed for carrying out the hydrological
and power potential studies. Design flood at diversion site has been
computed based on “Flood Estimation Report for Western
Himalayan Zone-7”. Design flood of 3050 cumecs has been worked
out.
4. POWER POTENTIAL STUDIES
Bajoli Holi HEP has been contemplated as a peaking station to
operate North Regional Grid. Installed capacity of the projet has
been presently kept as 180MW comprising 3 units of 60 MW each.
The project will generate 762.98 Gwh in 90% dependable year with
48% plant load factor.
5. POWER EVACUATION ASPECTS
The Bajoli Holi HEP is being developed as an up stream
development of Kutehr HEP (260 MW). The power from Bajoli Holi
HEP (180MW) has to be evacuated through LILO of 400 KV Kutehr
(260MW) and Hibra HEP (231MW) transmission line.
6. ENVIRONMENTAL ASPECTS
Environmental Management Plan (EMP) aims at the preservation of
ecological system by considering certain mitigating measures at the
proposed site. The EMP is required to ensure sustainable
development in the study area of 10 km. radius of the proposed
Bajoli Holi HEP site. Government regulating agencies like H.P.
Pollution Control Board working in the region and more
importantly the people living in the area need to extend their co-
operation and contribution in this direction.
It has been evaluated that the study area shall not be affected
adversely with the proposed activity, but is likely to get new
economical fillip due to hydel power generation, not only for the
study area but also for the region as whole.
7. ESTIMATES OF COST
The estimates of cost has been prepared on the basis of “CEA
Guidelines for Rates and Cost of Civil and Electrical works for
Preliminary Feasibility Reports of Hydro-electric Projects” received
during Oct. 2003. Accordingly cost of project works out to be Rs
41501 lac for civil works, Rs.16561 lac for electrical works and
Rs.3603 lac for transmission works based on June, 2004 price level.
8. FINANCIAL ASPECTS
The financial & economic evaluation has been carried out as per
CEA guide lines considering Interest During Construction (IDC)
@10% and interest on working capital @ 9.75%. The life of hydro-
electric project has been considered as 35 years. The 762.98 GWH
energy units are available at power house bus bars in 90%
dependable year and cost per unit at power house bus bars works
out to Rs 2.03 per Kwh in first year. The levelised tariff rate of
energy works out to be Rs.1.60 per Kwh at power house bus bars.
9. CONCLUSION
The economy of the Himachal Pradesh is predominantly dependent
on agricultural and allied sectors. The electric power being a vital
and essential infrastructure has a significant role to play in economic
upliftment of the state. The construction of project will provide
employment to the local people. The project will be completed
within four and half years period. Being an attractive project, it
deserves to be taken up for execution on priority.
BAJOLI-HOLI HYDRO ELECTRIC PROJECT (3X60 =180 MW) HIMACHAL PRADESH
1. INTRODUCTION The Bajoli-Holi Hydroelectric Project located in Chamba District of
Himachal Pradesh envisages utilization of the waters of the river Ravi for power generation on a run of river type development, harnessing a head of about 308m.
The project with a proposed installation of 180 MW (3x60 MW) would
afford net annual energy generation of 762.98 GWh, in a 90 % dependable year. The tariff at present day cost would be Rs 1.60/unit (levellised) at power house bus bars and Rs.1.93/unit (levellised) at purchase center.
The project is located between Latitude 32o16' North and 32o20' North,
Longitude 76o40' East and 76o32' East. The barrage site is approachable from Pathankot by road being at a distance of 222 kms approx. The nearest rail head is located at Pathankot and nearest airport is located at Jammu.
2. SCOPE OF WORKS The Bajoli-Holi HE project envisages construction of :
a 33m high diversion barrage across river Ravi to provide a net live storage of 79.95 hacm. with FRL at 2015.00 m and MDDL at 1993.00m;
two numbers desilting chambers of length 380m(L) and size 13m (W)x19.60m(H) to remove silt particles of size 0.20 mm and above;
a 14.60 km long and 5.0m dia. modified horse shoe shaped head race tunnel terminating in a surge shaft;
a 96m high ,12.0m dia surge shaft;
440m long, 4.0m dia pressure shaft;
a surface power house having an installation of 3 Francis driven generating units of 60 MW each operating under a net head of 278 m; and
450m long tail race tunnel to carry the power house releases back to the river Ravi;
The power generated from the project would be evacuated through. 220 KV single circuit line 35 Km long upto Kutehr power house to feed power to the power grid .
The Salient features of the project are given at Annex-I and a layout map
at Plate-I 3. HYDROLOGY The river Ravi drains a catchment area of about 760 sq.km. at the
proposed barrage site. The water availability for the project has been considered on the basis of 10-daily discharge series at Kutehr discharge site for the period 1972 to 1997. The discharge observations recorded on Ravi river at Bajoli just down stream of barrage site since June 1997 to May, 2003 has been used for determining a co-relation by regression analysis between the discharges at Kutehr & Bajoli. The design flood has been assessed as approx. 3050 cumecs.
4. POWER POTENTIAL STUDIES The computed inflow series for 31 years viz 1972-73 to 2002-03 has been
considered in the assessment of a power benefits from the project. As per GOI notification for tariff, the year 1987-88 corresponds to 90% dependable year. An installation of 180 MW comprising 3 generating units of 60 MW each has been proposed. The energy availability from the project in a dependable and an average year has been summarized below:
Particulars Dep. Yr. Avr. Yr.
Annual Energy Generation
Gross annual Energy Generation (GWh)
762.98 861.37
Annual Load Factor (%) 48 55
Generation during Lean Flow Season (Nov.-Feb.)
Energy Output (GWH) 44.64
Load Factor (%) 11 The design energy at 95 % machine availability in a 90% dependable year
has been worked out at 754.13 GWh. A net live pondage of 79.95 ham. has been provided in the diversion
barrage, which would enable the station to operate as peaking station. The
pondage is equivalent to 557.20 MWH which is sufficient to operate the station for 3.65 hours.
5. POWER EVACUATION ASPECTS It has been proposed to inject the power generated at Bajoli-Holi power
house into 220 Kv Kutehr HEP. For wheeling of power that shall be accumulated at Kutehr HEP, 220 Kv D/c line from Kutehr to Hamirpur with 2x0.5 or 4x0.5 conductor depending upon total firmed up capacities of projects up stream of Kutehr HEP, shall be laid.
6. ENVIRONMENTAL ASPECTS The project is located in tribal area of Chamba Distt. The total land
requirement for the construction of various components is 117.15 ha.,out of which private land is 25 ha. Based on assessment of environmental impacts, management plans have to be formulated for Catchment Area Treatment , compensatory afforestation and other environmental issues. These issues would be addressed during investigations for preparation of DPR.
7. ESTIMATES OF THE COST The project is estimated to cost Rs. 649.22 crores at power house bus bars
and Rs 668.35 crores at purchase center including IDC at June, 2004 price level. The preliminary cost estimate of the project has been prepared as per guidelines of CEA / CWC. The break down of the cost estimates is given below: Civil works : Rs. 415.01 Crores Electro Mechanical works : Rs. 165.61 Crores Sub total (Generation) : Rs. 580.62 Crores Transmission works : Rs. 36.03 Crores Total Cost : Rs. 616.64 Crores On Generation works Interest During Construction : Rs. 68.60 Crores Total : Rs. 649.22 Crores At purchase center Interest During Construction : Rs. 71.70 Crores Total : Rs. 688.35 Crores
8. FINANCIAL ASPECTS As indicated above, the Bajoli-Holi HE project with an estimated cost of
Rs. 649.22 (including IDC of Rs.68.60 crores) at power house bus bars and cost of Rs. 688.35 crores (including IDC of Rs.71.70 crores ) at purchase center with net energy of 762.98 GWH in a 90% dependable year. The project is proposed to be completed in a period of 4½ years. The tariff has been worked out considering a debt-equity ratio of 70:30, 16% return on equity, annual interest rate on loan at 10% and the tariff for first year and levellised tariff have been work out Rs. 2.03 /Kwh & Rs. 1.60/Kwh respectively at power house bus bars and Rs. 2.51 /Kwh & Rs. 1.93/Kwh respectively at purchase center.
9. CONCLUSIONS Bajoli-Holi HE project involves simple civil works and could be
completed in 4½ years. The project would afford a design energy of 762.98 Gwh in a 90% dependable year. The cost per MW installed capacity works out Rs. 3.23 crores. The Preliminary Feasibility Report indicates that the scheme merits consideration for taking up for Survey & Investigation and preparation of DPR.
Annexure-1
GENERAL PROJECT FEATURES
LOCATION
State Himachal Pradesh
District Chamba
River Ravi
Diversion barrage Near village Bajoli
Power house site Near village Barola
HYDROLOGY
Catchment Area at intake site 760 Sq. km.
Snow catchment 372 Sq. km. above El. 4000m
Mean annual rainfall at Bharmour 899 mm
Design flood 3050 cumecs
DIVERSION STRUCTURE
Type Gated Barrage
Length of Barrage at top ±100.00 m
Max. height from R.B.L 33.00 m
Top El. of Barrage 2018.00 m
Average River Bed level. 1985.00 m
FRL 2015.00 m
MDDL 1993.00 m
SPILLWAY
Design flood 3050 cumecs
Type Gated spillways with radial gates
Nos. of spillways, Crest elevation 6 Nos , El 1987.00
Size of gated spillway 6m x 8m, each.
Energy dissipation Stilling basin
Down stream bed level El. 1975m
INTAKE STRUCTURE
Type Semi circular
Crest level El. 1990.00 m
No. & size of opening 8 No., 5.50 mx3.0 m
FEEDER TUNNEL
No. 1
Size and type 6.00m dia, Circular concrete lined
Velocity 3.17m/sec
Length ± 300m
Design discharge from intake 89.67 cumecs
DESANDING BASIN
Type Underground.
No. of basins 2 nos.
Length of each basin 380m
Size of basins Width 13.00m, Depth 19.60m
Minimum particle size to be removed 0.2mm
Flushing tunnel, size 4.00m, D-Shaped
Flushing tunnel, length ± 1000 m
HEAD RACE TUNNEL
No. One
Size & Shape 5m diameter, modified
Horse shoe concrete lined
Length ±14600 m
Design discharge 71.74 cumecs
Slope 1 in 409 m
Velocity 3.65m/sec
SURGE SHAFT
Type Open to sky, Restricted orifice type
Size 12.00 m dia cricular
Orifice 2.15 m dia
Maximum upsurge level El.± 2043 m
Minimum down surge level El.± 1960 m
Bottom level El±.1954 m
Top level El.± 2050 m
PRESSURE SHAFT
Type Underground
Size:
Main 1 No., 4m dia, ± 440 m long
Branches 3 Nos., 2.30 m dia, ± 20 m long each
Velocity 5.74 m/sec.
POWER HOUSE
Type Underground
Installed capacity 180 MW
No. and capacity of unit 3 Nos. 60 MW
Size of machine hall 50 m x 17 m x 35 m
Type of turbine Francis turbine
Speed of turbine 500 RPM
Gross Head 308 m
Normal tail water level 1700 m
Net operating head for design discharge 278 m
Peaking duration 3 hrs .
TAIL RACE TUNNEL
Shape D-Shaped
Dia 5.00 m
Length ± 450 m
SWITCH YARD
Type Surface
Size 170 (L) x 35 m (W)
TRANSMISSION LINE
No. of circuits S/C Line
Length of each 35 km.
Voltage 220 KV
POWER GENERATION
Installed capacity 3x60 MW
Annual energy generation
90% dep. Year 762.98 GWH
50% mean year 861.37 GWH
COST ESTIMATE & FINANCIAL ASPECTS
COST ESTIMATE
Capital cost of the project (At Price level June. 2004):
Civil works Rs. 415.01 Crore
Electrical works
(P-Production) Rs. 165.61Crore
T-Transmission Rs. 36.03 Crore
Total Rs 616.64
Capital cost of Generation Rs. 649.22 Crore
(Including IDC Rs. 68.60Crore)
Loan 70% Rs. 454.45Crore
Equity 30% Rs. 194.76Crore
Capital cost at purchase center Rs. 688.35 Crore
(Including IDC Rs. 71.70Crore)
Loan 70% Rs. 481.84Crore
Equity 30% Rs. 206.50Crore
FINANCIAL ASPECTS
Cost of generation per MW of
Installed capacity Rs. 3.23Crore
Levelized tariff at PH Rs. 1.60/Kwh
Bus bars in 90% dep. Year
Levelized tariff at purchase center Rs. 1.93/Kwh
in 90% dep. Year
Energy available for sale in 90% dep. Year 753.82GWH
(Auxiliary consumption @ 0 .7% &
Transformation losses @ 0.5%).
at power house bus bars
