Section - I EXECUTIVE SUMMARY 1.1 THE PROJECT The Pahumara Small Hydel Project is located on the river of the same name. The project is located in the Baksa District of Assam near village Laugaon. It is proposed to have an installed capacity of 2000 Kw e consisting of two (02) units of 1000 Kw e each. The project has been conceived as a run of the river project with diurnal storage. The existing Pahumara irrigation barrage is used as the diversion weir. 1.2 PROJECT PURPOSE The Pahumara SHP has been proposed to be developed for augmenting the power generation in Bodo Territorial Council area of the State of Assam especially using renewable energy source and for helping in rural electrification of the State. After commissioning of the Pahumara Small Hydroelectric Project, the electrical energy produced shall be utilized for 1 . PAHUMARA - SHP
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Section - I
EXECUTIVE SUMMARY
1.1 THE PROJECT
The Pahumara Small Hydel Project is located on the river of the same name. The
project is located in the Baksa District of Assam near village Laugaon. It is proposed to
have an installed capacity of 2000 Kwe consisting of two (02) units of 1000 Kwe each.
The project has been conceived as a run of the river project with diurnal storage.
The existing Pahumara irrigation barrage is used as the diversion weir.
1.2 PROJECT PURPOSE
The Pahumara SHP has been proposed to be developed for augmenting the
power generation in Bodo Territorial Council area of the State of Assam especially using
renewable energy source and for helping in rural electrification of the State.
After commissioning of the Pahumara Small Hydroelectric Project, the electrical
energy produced shall be utilized for augmenting the energy supply in the local rural
distribution network in the Jalah Block of Baksa District and shall provide electricity to
un-electrified villages. The energy availability will also improve the voltage profile and
reliability of the power system in this remote area in and around Laugaon.
1.3 WATER RESOURCES
Pahumara is a hilly stream and is a tributary of river Brahmaputra. It has its origin
from the southern water shed of Arethumake of Bhutan range of Assam Himalayas.
Pahumara is a perennial stream with a minimum flow of around 2.94 cumec (for 90%
dependable year 1974) after meeting the irrigation requirement and a maximum flow of
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948.32 cumec (33457 cusec). The stream has a catchment area of 440 sq.km at the
Kathalmurighat barrage site. The river flows through mixed jungle.
1.4 GEOLOGY AND GEOTECHNICAL ASPECTS
The small hydropower stations do not require construction of any heavy
structures. The geology along the location of various project components have been
found to be favourable for founding these structures. The location of various structures
including the power plant and alignment of the power channel and the tail race channel
have been made keeping in view the slope and structural stability.
1.5 POWER PLANT
The power plant is proposed to have two (02) turbine – generating units each of
1000 Kwe output at generator terminals. The turbines shall operate under a net head
varying between 7.2 m and 6.315 m. As for this head and variable discharge, Kaplan
turbines are suitable, the same has been proposed. The turbine-generators shall be of
vertical shaft type alignment.
The generation voltage shall be at 3.3 KV which shall be stepped upto 11 KV
through a common step-up transformers of 2500 KVA capacity. There is an existing
11 KV line upto the barrage site which shall be used to evacuate the power generated.
Each of the generators shall be provided with brushless excitation system and all
standard protections for generators and transformers of this capacity shall be provided.
1.6 FINANCIAL ASPECTS
The average annual energy expected to be produced from the proposed project
is 9.34 x 106 kwh and the net energy available for sale is expected to be 8.784 x 106
kwh at 95% plant availability. The plant load factor is 50.64%.
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The design energy of the project is 6.853 x 106 kwh, and the net energy available
for sale i.e. 6.785 x 106 kwh.
The estimated cost of the project is Rs. 1413.00 lacs out of which the cost of the
civil works is Rs. 683.00 lacs and the cost of electro-mechanical works is Rs. 653.00
lacs. There is an existing 11 KV line upto the barrage site which shall be used to
evacuate the power generated.
The cost of generation in the first year of operation is estimated at Rs. 3.49 per
kwh and on levellised cost basis over a 35-year period works out to Rs. 3.12 per kwh.
The gross revenue in 50% dependable year is estimated at Rs. 281.20 lacs with sale
price of energy at Rs. 3.20 per kwh (levellised sale price). The return on equity after
meeting all operating expenses, tax, but including depreciation is estimated at 20.1 %
on levellised cost basis over a 35-year period.
1.7 FINANCING OF THE PROJECT THROUGH CDM
The CDM facility was established in August 2003 to assist Developing Member
Countries (DMCs) to access new development opportunities made possible through the
Clean Development Mechanism (CDM).
Its main objectives are as follows:
Promote projects that contribute to poverty reduction, sustainable development,
and greenhouse gas (GHG) mitigation.
Lower CDM transaction costs by supporting CDM project identification,
development, registration , and implementation.
Help find competitive prices for Emission Reductions (ERs), or carbon credits,
arising from projects.
Facilitate access to underlying-finance by improving project viability.
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The CDM facility is applicable to both sustainable development benefits and
GHG mitigation. These include:
Renewable energy
Energy efficiency
Sustainable agriculture,
Forestry.
It is estimated average annual energy production from the Pahumara SHP shall
be 8.873 x 106 KWh (allowing for 5% forced outage) and the energy available for sale
be of the order of 8.784 x 106 kwhr per annum. The coal being used in the thermal
power stations in India not being of very good quality, it may be appropriate to assume
that the carbon dioxide being emitted shall be of the order of 987 gms per kwh. On this
basis the carbon dioxide emission reduced by generating same amount of electrical
energy from Pahumara SHP works out to 8.75 x 106 kg per annum which equivalent to
8750 tonnes per annum. On this basis over the life time of power plant the carbon
dioxide reduction is expected to be of the order 3,06,500 MT. Since the Pahumara SHP
is a renewable energy project and its operation can provide energy for social and
sustainable development without contributing to GHG emissions is eligible for financing
under CDM facility as envisaged in Article 12 of the Kyoto Protocol.
1.8 RECOMMENDATIONS
The project is technically suitable and financially attractive and hence
recommended for execution.
******
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Section - II
SALIENT FEATURES
1. Location :(i) State : Assam (ii) District : Baksa
Bodo Territorial council (BTC)(iii) Block : Jalah(iv) Village : Laugaon (v) Access-road
From nearest air port - Guwahati Nearest rail station - Barpeta road
:
:::
10 kms from NH-31 at Bhawanipur point
148 kms 33 kms
(vi) Geographical Coordinates
LongitudeLatitude
:::
Powerhouse site
910 1 E 260 37 N
(vii) Altitude : 50 m above msl2 River Catchment
(i) Catchment : 440 sq. km.
(ii) Name of River : Pahumara(a tributary of Brahamaputra)
3. Type of Project : Low head, run of the river type with diurnal storage
(a) Diversion Structure (Head works)(i) Type of structure weir/barrage Barrage type weir of RCC(ii) Length of barrage : 172 m (iii) Maximum discharge capacity (cumecs) : 1699 cumec(iv) Number of undersluices (Existing) : 5 bays (v) Number of weir bays (Existing) : 18 (vi) Normal pond level : 49.60 m(vii) Maximum water level ; 49.60 m(viii) Crest level of undersluices (existing) : 44.75 m(ix) Top level of guide bund (existing) ; 52.5 m(x) Top width of crest (existing) : 2.0 m
4. Head Race Channel :(a) Shape : Rectangular(b) Bed width (at the entrance) : 9.5 m
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(c) Length : 43.4 m (d) Bed slope : 0.1 m in 43.4 m (e) Fully supply depth : 4 m (f) Free board : 1 m
5. Forebay :(a) Live storage volume : 350 cum.(b) Dimensions (length x width x depth) : 25 m x (9.5 x to 15) x 10(c) Free board : 1.0 m
6. Power Station :(a) Type : Surface(b) Design head : 6.3 m(c) Power station dimensions :
Length : 23.5 m Width : 9.86 m Height : 27.5 m
(d) Proposed installed capacity : 2 x 1000 Kwe(e) Number of units : 2(f) Design discharge : 38.60 cumecs
(g) Firm power (at 90% dependable discharge)
: 260 kW(4.62 cumec)
(h) Design energy : 6.853 x 106 kwh7. Turbine :
(a) Type : Vertical axis Kaplan(b) Number : Two (c) Capacity : 1063 kw (d) Diameter of runner : 2100 m(e) Rated head : 6.4 m (f) Rated discharge per unit : 19.3 cumec
8. Generator :(a) Type : Synchronous (b) Number of units : 2(c) Number of phases : 3(d) Frequency : 50 (e) Rated output : 1000 KW(f) Rated voltage : 3300 V
9. Power Station Crane : Hand operated bridge crane – 15 tonnes
10. Switchyard :(a) Voltage level : 11000 / 3300 V(b) Number of bays : One + one for auxiliary power
transformer(c) Number of step up transformers : One(d) Transformer capacity : 2500 kVA(e) Transformer mounting : Plinth mounted(f) Auxiliary power transformer
VoltageNumber
:::
125 KVA 11000 V / 433 VOne
11. Tail Race :(a) Shape : Trapezoidal (b) Length : 85.0 m (c) Bed width : 30.0 m (d) Bed slope : 0.1 m in 85 m (e) Full supply depth : 1.2 m (f) Free board : 1.0 m
12. Estimated cost :(a) Project cost : Rs. 1413 lakhs (b) Cost of electro-mechanical equipment : Rs. 653.0 lakhs (c) Cost of civil works : Rs. 683.00 lakhs (d) Total project cost including IDC : Rs. 1566.33 lakhs (e) Cost per KW installed : Rs. 78320.00
13. Benefits :(a) Design Energy : 6.853 x 106 kwh(b) Average energy available for sale per
annum: 8.784 x 106 kwh
(c) Plant load factor : 50.6 %(d) Cost of Generation per KWh (on
levellised cost basis): Rs. 3.12
(e) Annual revenue at sale price of Rs 3.20 per kwh
: 281.10 lakhs
14. Financial performance indicator :(a) Return on equity (levellised) : 20 %(b) Cumulative cash accrual on equity of
Rs. 437.93 lakhs: Rs. 4269.35 lakhs
*******
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Section – III
CHECK LIST
1 NAME OF THE PROJECT PAHUMARA SHP
2. LOCATION
a. State Assam
b. District BaksaBodo Territorial council (BTC)
c. Block Jalah
d. Village Laugaon3. CATEGORY OF THE PROJECT
a. Small Hydel Hydroelectric scheme with a total installed capacity upto 25000 KW
2 x 1000 KW
4. PLANNING Has the overall development of the stream/canal been prepared and stages of development discussed ?
Yes
Have the alternative proposals been studied and their merits and demerits discussed ?
Yes
Have the detailed topographical surveys been carried out for the following items and drawings prepared as per prescribed scales ?
Yes
a. Head work surveys (weir or diversion structure) Yesb. Desilting tank Yesc. Water conductor system Yesd. Forebay Yese. Penstock. Yesf. Power house, Tailrace etc. Yes
5. GEOLOGY 6. FOUNDATION INVESTIGATIONS
Have the general surveys regarding construction materials like pervious and impervious soils, sands, aggregates, etc. been carried out ?
Yes, as applicable and necessary
7. HYDROLOGICAL & METEOROLOGICAL INVESTIGATIONS Have the hydrological investigations been carried out and status of discharge data of stream/canal discussed in reports ?
Yes
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8. HYDROLOGY Have hydrological studies been carried out to establish the availability of water for the benefits envisaged, and what is the dependability of the potential ?
Yes50% Dependability
9. LAND ACQUISITION & RE-SETTLEMENT (Whenever Applicable) Have the provisions for land acquisition and resettlement been considered ? Have the socio-economic problems involved in resettlement been investigated & discussed?
Yes-provision for land acquisition has been made.No - Re-settlement is not involved
10. DESIGN Has the layout of the project area viz., location of diversion structure, powerhouse etc. been finalized ? Have the preliminary designs been prepared for the following components ?
Yes
a. Diversion Weir. Yesb. Penstock and water conductor system, etc. Yesc. Power house etc.
Yes11. POWER BENEFITS
Have the following been discussed ? a. Total energy production and installed capacity of the
system Yesb. How does the scheme fit into overall development of
power of the region ? (as applicable ).Power station being developed for meeting the electrical power requirements especially in rural areas of Assam
c. Energy generation from the project, firm power etc. Saleable energy : 8.784 million kw hrs annually on average
d. Proposal for transmission and/or connecting to the existing system, etc. (wherever applicable).
11 KV single circuit line existing upto the barrage site shall be used for power evacuation
e. Cost of generation per kwh installed as compared to the various micro hydel projects and services in the region of justify the economic viability of the scheme.
Rs. 3.20 per kwh is comparable to the cost of other canal based low head hydropower station in the region. Further, the cost is less than
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the cost of energy purchased by Assam State Electricity Board from Central Generating Stations and Private Generating Stations.
12. CONSTRUCTION PROGRAMME Are the major components of work proposed to be done departmentally of through contractor ? Have the quantities of the following items been worked out for various components of the project ?
Through Contractor
Yes
a. Excavation –soft & hard strata Yesb. Earthwork in filling (wherever applicable) Yesc. Stone for masonry Yesd. Coarse aggregated for concrete Yese. Steel for reinforcement. Yesf. Other materials – P.O.L., Electricity
Yes13. ESTIMATE a. Is the estimate prepared ? Yesb. Have the analysis of rates for various major items and the
components of the project been furnished, with basis of analysis & the price index ? Yes
14. ECONOMICAL & ENVIRONMENTAL ASPECTS Is the area likely to the environmental and ecological problems due to the altered surface water pattern and preventive/corrective measures discussed ? (wherever applicable)
No Environmental and ecological degradation. For environmental preventive and corrective measures a sum of Rs. 0.50 lacs has been provided for in the cost estimates
15. CAMP AND BUILDINGS : Has the planning of the camps/building been done ?
Yes16. SOIL CONSERVATION
Is the need for soil conservation measures in the project discussed ?
Not required
******
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CHAPTER – 1
SCOPE OF THE PROJECT
1.1 PROJECT PLAN AND PURPOSES
It is proposed to harness hydro energy available at the barrage site on the river
Pahumara located near the village Laugaon in the district of Baksa in the State of
Assam. The barrage has been constructed to feed one canal on the right bank. The
Pahumara river, alongwith its numerous tributaries, originate from the southern
watershed of Arethumke peak of Bhutan range of Assam Himalayas and pass through
vast areas of open mixed jungles within the North Kamrup reserved forest before joining
the Brahmaputra.
The discharge in the river is much more than the irrigation requirements. It is
proposed to utilize the head available by ponding the upstream of the barrage and the
surplus water flowing through the barrage (at present after meeting the irrigation
requirements).
The maximum (pond) water level is 49.60 m above msl. The average river bed
level at a distance of above 200 meters downstream of the barrage is 41.8 meters. Thus
a gross difference of 7.8 meters is available between the pond level and the river bed
level.
The maximum and minimum discharge passing through the barrage after
meeting the irrigation demand are 53.35 cumec and 15.73 cumec in a 50% dependable
year and 50.52 cumec and 2.94 cumec in a 90% dependable year respectively as per
the river discharge data available over a period of 6 years. On the basis of this
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discharge data, water power studies have been conducted, which has resulted in the
possibility of establishing a hydropower station on the left bank of the river (barrage). It
is proposed to install a power generating facility comprising of 2 units of 1000 KWe
rating each, aggregating to 2000 KWe installed capacity with a plant load factor of
50.6% on average.
The electrical energy generated from this project would meet the needs of the
villages in the vicinity and in the backward districts of Baksa, Kokrajhar and Barpetta
which will improve the power availability in the region and help accelerate socio-
economic development. Besides, the project would also help reduce the energy
shortage of 5.40% and peak power shortages of 5.80% of the state of Assam (Ref.
2004 – 2005 statistics – source: North – Eastern Region Power Sector Profile, Ministry
of Power, Govt. of India January 2006).
1.2 PROJECT COMPONENTS
The proposed project shall be of ‘run-of-the-river” type for the generation of
hydroelectric energy.
The proposed Pahumara SHP shall consist of the following major system
components:
(1) Head race channel
(2) Road bridge (conforming to IRC Class A) on head race channel.
(3) Intake structure with trash rack and stop-log gates with hoist arrangement.
(4) Vertical axis Kaplan turbines coupled to synchronous generators through
appropriate speed increaser – 2 sets, each of 1000 KWe capacity.
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(5) One (01) 15 tonne capacity bridge crane H.O.T for the turbine generator
room.
(6) One (01) 10 tonne capacity gantry crane for intake gate operation.
(7) One (01) set of generator and turbine control and protection cubicles with
measuring, recording, and indicating instruments, protective relays and
annunciation system.
(8) SCADA system
(9) Pond level controller
(10) Two numbers of drainage pumps.
(11) One number step-up transformer 3.3 KV / 11 KV, 2500 KVA with associated
current and voltage transformers (CTs and PTs) and vaccum circuit breaker.
(12) Draft tube gates – 2 nos.
(13) Monorail with gate hoist (7.5 tonnes) for operating draft tube gates
(14) Tail race channel.
In the event of tripping of the unit / units, the inflow into the upstream of the pond
shall be made of flow to the downstream of the river by opening of the barrage gates as
required. The opening and closing of the gates shall be controlled by a level controller to
be installed on the upstream of the barrage. To avoid overtopping of the banks, the level
controller shall be provided with adequate redundancy.
1.3 PROJECT BENEFITS
It is estimated that on average 8.784 x 106 Kwhrs of electrical energy shall be
available for sale after meeting the energy required for auxiliary power consumption.
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The project when completed would result in conservation of 8800 tones of coal
annually thereby providing a cleaner environment for future.
Further, the project since uses renewable resource for power generation would
benefit the global reduction of carbon – dioxide (green house gas) pollution by 8750
tones annually.
1.4 CONSTRUCTION MATERIAL
Fine aggregate and coarse aggregate are available in the river bed nearby and in
u/s reaches . Coarse aggregate boulders are to be collected from the u/s reach river of
and crushed for use in the structures.
Cement from reputed manufactures is available from dealers at Bongaigaon and
Kokrajhar which are within a distanced of about 25 / 30 kms from the project site.
Structural and reinforcement steel can be obtained from the Stockyard of Steel
Authority of India Ltd. (SAIL) located at Guwahati at a distance of 150 kms from the
project site.
1.5 CONSTRUCTION PROGRAM
The construction of the project comprises of the following major activities:
- Excavation of approach channel p.u. pit and tail race channel.
- Power station raft foundation.
- Dewatering
- Construction of head race channel, road bridge, intake and power
house structure, tailrace channel.
- Erection and commissioning of power plant equipment, trashrack,
cranes, gates (intake and draft tube).
- Dismantling of the to upper portion of left side retaining wall u/s of head
regulator of irrigation canal and to construct approach channel to
forebay.
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- Construction of 11 KV switchyard and connecting the existing 11KV
line.
The above works can be completed within twenty four (24) months from the date
of technical and financial closure of the project. Preparation of tender specifications,
issue of notice inviting tenders, tender evaluation, and placement of orders can be
completed within six months from the date of start of the project, which is included
within the above mentioned period of twenty – four months. Temporary sheds for
construction storage, and accommodation of construction staff also be constructed
during the first six – month period. The existing building at the barrage site on the left
bank can be used for locating the site office.
1.9 CONSTRUCTION POWER
It is estimated that a maximum of 250 KVA of power would be required at the
project site including power required for dewatering. There is already on existing 11 KV
line upto the barrage site. The construction power shall be drawn from this line.
However, as a standby, it is proposed to install a 100 KVA Diesel Engine driven (DG)
set for taking care of any contingency.
1.10 ENVIRONMENT AND ECOLOGY
Since the power plant is proposed to be set-up adjacent to the existing barrage
and within the land owned by the irrigation department, no adverse effect to
environment and ecology in the vicinity is expected.
Since the water diverted from the upstream of the barrage is again let out into the
same river about 150 metres downstream, the threat to aquatic life in the downstream
stretch of the river is non-existent. Besides, leakage of water through the barrage gate
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seals would not dry-up the river in the downstream of the barrage upto the junction of
the tail race channel with it.
There is no wild life habitat including breeding, feeding and migration route within
the project periphery. It is also not a potential site for wild life sanctuary.
There are no rare or endangered species of flora and fauna within the project site.
There are no monuments of cultural, historical, religious or archaeological
importance within the project boundaries.
It is also not a spot used for recreation at present. However, it is likely that after
the site is developed for power generation, by creating a pool upstream of the existing
barrage, the head pool could be developed as a place for recreation by provision of
boating facilities. Further, the upstream pool could be used for developing fishery and
pisciculture, which will increase availability of local and fresh fish in the villages and
towns nearby. It may be worth mentioning here, that fish is the staple food of the state,
and presently fish is being imported from far away places like Andhra Pradesh and Uttar
Pradesh for meeting the growing demand.
There are no trees within the project boundaries. However after completion of the
project, trees with commercial value can be planted along the tail race channel and the
head pool to enhance the environment and ecology of the area. Appropriate provision of
Rs. 0.50 lakhs has been made in the budget estimates for plantation of trees, and land
scaping around the project area.
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1.11 LAND ACQUISITION
The entire project is proposed to be aligned within the land owned by the
Government of Assam and hence no difficulty in acquisition of land is envisaged. The
land required for the project area 0.81 hectares.
1.12 PROJECT COST
The total cost of the project is estimated at Rs. 1413.00 lakhs without escalation
in cost and interest during construction, and Rs. 1566.33 lakhs with escalation in cost
and interest during construction. The cost of civil works and electro-mechanical works
are stated as below:
Cost of civil works : Rs. 683.00 lakhs
Cost of electro-mechanical : Rs. 633.00 lakhs
Cost of power evacuation : Rs. 20 lakhs
Cost of land : Rs. 2 lakhs
Expenditure on pre-project Development works : Rs. 75.00 lakhs
It is proposed that the phasing of expenditure shall be as follows with debt to
The various construction material required for the project are available in the
vicinity of the project site. The sources have been identified keeping in view the
technical specifications applicable to each type of construction material and the
quantities required.
The following is lead statement of various construction material.
Material Source Distance (km)Sand, Stone, gravel, boulders
River bed Safekamar quarries
5 km15 km
Cement 25 / 30 kmSteel 25 / 30 km
The sand, stone, gravel and boulders are available in the river bed in sufficient
quantity from where it can be collected for the construction purposes.
6.2 SPECIAL MATERIALS
Materials like CGI sheets for roofing of the power station, fixtures etc. would have
to be procured from Bongaigaon or Guwahati (150 kms).
Generating equipment, electrical and mechanical equipment, gates, hoists, trash
racks etc. would have to be specially manufactured to order and transported to site and
installed as and when required. All the equipment proposed are indigenously
manufactured and no import of equipment is envisaged.
6.3 OTHER MATERIAL
Items like checkered plates for covering cable trenches, glass panes for windows
etc., can be procured from Guwahati (150 kms).
******
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CHAPTER – 7
PROJECT PURPOSES
7.1 GENERAL
Government of India is presently giving top priority to the development of Small,
Mini and Micro Hydro Stations for augmenting electricity generation in the country due
their short gestation period besides being environmentally benign.
7.2 PRESENT STATUS AND PROJECTS OBJECTIVES
Once the project is completed, it will on average supply 8.78 million kwhrs of
electrical energy to the Assam State Electricity Board Grid, which will meet the energy
requirements partially. Further, this power station, being located in the midst of vast
tracts of agricultural and where substantial amount of electrical energy is being used for
pumping ground water for agricultural production, shall meet their requirements and
also will reduce transmission losses in Assam State Electricity Board grid.
Further, the energy so produced shall help in reducing atmospheric pollution by
Carbon dioxide and Flyash by reducing carbon-di-oxide production by 11,100 tones and
3000 tones of flyash from the thermal power stations. This objective is in consonance
with the Kyoto-Protocol on world environment.
******
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CHAPTER – 8
CONSTRUCTION PROGRAMME
8.1 GENERAL
The civil works for the project includes; head race channel, road bridge over
head race channel, intake structure, power house building to house turbine and
generation equipment along with control and protection equipment, draft tube, tail pool,
tailrace channel and switchyard. The head race channel is proposed to take off
diagonally between approaches of barrage and the right bank main canal. The intake
structure is to be constructed on the upstream of the power station structure and
integral with the same. It is proposed to cut a rectangular notch through the retaining
wall upstream of the head regulator for the main canal. The tail race channel joins the
Pahumara river about 150 m downstream of the existing Pahumara barrage.
The power house is proposed to be completed in a period of 24 months which
includes 3 months for preparing tender documents. Tender specification are to be
invited separately for execution of civil works, supplying and installing mechanical
equipment and electrical plant. During the period the tender formalities are being
complied with action for acquisition of required land is envisaged. Accommodation for
residential and non-residential purposes and other ancillary facilities are also required at
the site as no facilities are available at the site. It may perhaps be possible to avail the
facilities available in the irrigation department rest house located nearby, for which
Assam Irrigation Department has to be contacted by the developer.
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8.2 MATERIAL PLANNING
Chapter 6 gives the sources of various construction materials and their
availability.
8.3 CONSTRUCTION POWER
The power supply will be required at the power house site. About 250 KVA will be
required for operating the concrete mixer and vibrators and the dewatering pumps. The
existing 11 KV line of Assam State Electricity Board to the barrage site and located
within the project area can be tapped at a suitable point.
8.4 MANPOWER PLANNING
The construction agency executing the power house will arrange its own
manpower as required.
8.5 DEWATERING
Dewatering shall be required when the foundation is excavated due to proximity
to the river which runs almost continuously. The contractor will have to make his own
arrangement for pumps required for dewatering.
8.6 REQUIREMENT OF CONSTRUCTION EQUIPMENT
For civil works of the power house, the main equipment required will consist of:
(a) Earth excavators like JCB etc.
(b) Concrete mixer and vibrators for producing and compacting plain and
RCC,
(c) Air compressor, rock drills, diesel generating set as a standby, welding
set, chain pulley block and tripod.
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The project estimate does not include provision of these equipment as these
would be arranged by the construction agency. No difficulty is envisaged in arranging
these equipment as these are indigenously available.
8.7 METHOD OF CONSTRUCTION
The work is proposed to be done through contractor.
8.8 SUPERVISORY STAFF
During execution, supervisory staff for both civil and mechanical – electrical
works being carried out will have to be posted by the developer. Provision for
establishment has been made at the rate of 4% of the I-works (details of which are
given in Chapter – 14).
8.9 SERVICES AND UTILITIES
The staff for operation and maintenance would be appointed by developer.
However, it is proposed that the O&M staff be appointed by the time the erection of
electro-mechanical equipment starts so that they get acquainted and are trained in the
process. Residential facilities may be constructed at the site or accommodation on hire
can be taken at the nearest villages / towns of Pathsala and Sarupeta where such
facilities are available.
8.10 BAR CHART
A bar chart showing the construction of works has been included in this report.
The programme includes the civil works, and supply and installation of mechanical and
electrical equipment (Fig. 8.1).
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BAR CHART
(two pages)
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CHAPTER – 9
ENVIRONMENTAL AND ECOLOGICAL ASPECTS
9.1 SITE SELECTION
The site of the power station has been selected on the left bank of the Pahumara
river. The power station will be located on a bypass channel to be constructed from the
Pahumara river upstream of the existing barrage.
9.2 PHYSICAL ASPECTS
The approach channel and the forebay is aligned in an area where there are no
constructions. The land is owned by the Assam Irrigation Department.
The land which to be utilized for the project purposes does not have any tree and
is almost barren with some small bushes, scattered here and there. There are no
plantation with any commercial value.
There is no wild life habitat including breeding, feeding and migration route at the
site. It is also not a potential site for wild life sanctuary. There are no rare or endangered
species of flora and fauna at the proposed site.
There are no monuments of cultural, historical, religious or archaelogical
importance at the proposed site. It is also not a spot used for recreation. However, it is
likely that after the site is developed for power generation, the surrounding area could
be developed into a picnic spot and a place for recreation.
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9.3 RESOURCE LINKAGE ASPECTS
The impact of construction materials on the environment is virtually negligible in
view of very small quantity required for the construction of the power plant and
appurtenant works.
There would also be no impact due to migration of construction workers to the
project site since the number of workers envisaged at the peak of construction is
approximately fifty (50).
9.4 PUBLIC HEALTH ASPECTS
The maximum number of construction workers at the peak period is not likely to
exceed fifty (50) persons. The civil construction work is likely to take not more than six
(06) months. Necessary sanitary and health facilities shall be provided for the workers
by the contractor.
9.5 PREVENTIVE AND CORRECTIVE MEASURES
The project would enhance the aesthetic aspects of the site. To improve the
aesthetics of the site as well as to improve upon the vegetal cover, it has been provided
for in the project estimate for planting of trees around the project site.
9.6 ESTIMATION FOR MEASURES
There is no specific necessity for conducting environmental studies/surveys for
the power station, being exempted under the relevant act of the Government of India.
As there is no virtual impact on the environment, there is no necessity for
initiating any remedial and mitigative measures.
A sum of Rs. 50,000/- has been provided for in the project estimate for meeting
the expenditure on land scaping and plantation around the power station.
******
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CHAPTER – 10
WATER AND POWER STUDIES
10.1 DATA AVAILABLE
The discharge data has been monitored by the Assam irrigation Department from
the years 1965, 1966 and from 1972 to 1975 (6 years) which they have used for the
planning and design of the Pahumara Irrigation Project including the Pahumara barrage.
The discharge data for this period has been taken from the “Revised Project Report for
the Pahumara Irrigation Project” prepared by the Assam Irrigation Department and
presented in Table 4.1.
10.1.1 Discharge for Power Generation
It is envisaged to utilize the surplus discharge available at the Pahumara barrage
at Kathalmuri ghat for power generation purpose. Therefore from the discharges
available at the Kathalmuri ghat barrage site irrigation requirements through the left
bank and the right bank canals have been deducted to arrive at the surplus flow
available at the barrage site to be utilized for the power generation purposes.
For planning of small hydroelectric projects, it is considered adequate to use
three years discharge. However, since the discharge data is available for a longer
period (i.e., for 6 years), it has been considered desirable to analyze the entire six years
data for planning of the proposed Pahumara SHP.
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10.1.2 Head
The gross head is the difference in elevation between the water surface levels in
the upstream of the barrage and the downstream of the barrage.
As the project is a low head development, it is proposed to maintain the barrage
pond level (49.6 m above mean sea level) as the upstream level, in order to maximize
the head availability and the consequent energy productivity.
From the topographical survey of the river downstream of the barrage, at a
distance of about 150 metres from the barrage axis, a suitable site has been identified
where the tail race channel can join the river. This site has been identified on the basis
of the following considerations:
- The length of the head race and the tail race channel is minimum,
- The bed level of the river does not change appreciably, if the length of
the tail race channel is further increased, or in other words, if a lower
river bed level is to be attained (for achieving higher head), a much
longer tail race channel is required which is not economically justified.
At the site of the confluence of the tailrace channel with the river channel, the
river cross section has been plotted and the water level in the river corresponding to the
discharge has been calculated.
Similarly, the bed width of the tail race channel has been taken as 30 metres, so
that when the power discharge flows through this channel, the depth of flow does not
exceed 1.03 m. This has been chosen to achieve a higher available head for power
generation.
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The river bed level at the point of confluence is 41.7 metre (above mSL). With a
slope of 0.1 metre from the tailrace channel with a length of 85 metres, the bed level of
the tailrace channel works out to 41.8 m (mSL). The tail water rating curve has been
prepared for different flows. The tail water rating curve is shown in Fig. 10.6.
10.2 INSTALLED CAPACITY
For deciding the installed capacity, four alternative scenarios have been created
and evaluated. The alternatives are:
Alternative (1) : Installed capacity of 2 x 750 KWe = 1500 KWe
Alternative (2) : Installed capacity of 2 x 1000 KWe = 2000 KWe
Alternative (3) : Installed capacity of 2 x 1250 KWe = 2500 KWe
Alternative (4) : Installed capacity of 2 x 1500 KWe = 3000 KWe
The water power studies have been conducted with the above four alternatives
for the entire six calendar years i.e. for 1965, 1966 and from 1972 to 1975. Thus, the
simulation studies conducted for these years amply reflects the total likely scenario as it
covers a long period of six years.
The energy generated for each of these alternatives, year-wise are shown in
Figures 10.1, 10.2, 10.3 and 10.4.
The comparative performance of these four alternatives are tabulated below in
Tables 10.1, and Table 10.2 and also diagrammatically displayed in Figure 10.5.
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Table 10.1
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Table 10.2 : Utilization of the generating units in the 50% dependable year
Utilization of unit in nos. of days per year Nos. of units 2 x 750 KWe 2 x 1000 KWe 2 x 1250 Kwe 2 x 1500 KWe
One unit 365 365 365 365Two units 150 130 100 60
From the Table 10.1, it is evident that the incremental energy increases when the
installed capacity is increased from 1500 KW (2 x 750 KW) to 2000 KW (2 x 1000 KW),
but decreases when it is increased to 2500 KW (2x 1250 KW). This clearly shows that
the optimum installed capacity for the Pahumara SHP is 2 x 1000 KW. This decision is
also further buttressed by the fact that the plant load factor for an installed capacity of
2 x 1000 KW is 53.3% whereas the same for an installed capacity of 2 x 1250 KW is
45.6% before accounting for forced outage, auxiliary consumption and transformation
losses.
Further, the use of two units is justified as can be seen that with the alternative of
2 x 1000 KWe, the second unit is required to be operated for about 130 days (4.3
months) in a year. This solution gives an opportunity that spare capacity is available for
a reasonable time to take care of annual maintenance and forced outage of one unit in
operation.
If the plant load factor in the 90% dependable year is considered, the plant load
factor with an installed capacity of 2 x 1000 KW is 41.2% whereas the same for the
installed capacity of 2 x 1500 KW is 33% which is considered to be low enough.
In consideration of plant load factor (> 50% on average and > 40% in the 90%
dependable year) flexibility in operation and maintenance, part load operation and
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indigenous manufacturing capability of runner, it is proposed to install two units of 1000
KWe each.
10.3 DESIGN ENERGY
The design energy is the energy likely to be produced in the 90% dependable
year with 95% availability. From the hydrological data for the Pahumara Barrage, 1975
is the 90% dependable year. From the power generation simulation studies conducted
for this year with 2 units of 1000 KWe each, the energy likely to be produced is 7.214 x
106 KWhrs. With 95% availability, the design energy is calculated to be 6.853 x 106
Kwhrs.
********
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Fig. 10.1
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Fig. 10.2
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Fig. 10.3
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Fig. 10.4
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Fig. 10.5
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Fig. 10.6
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CHAPTER – 11
INTAKE AND TAIL RACE WORK
11.1 HEAD RACE CHANNEL
The head race channel takes off from the left bank of the river at a distance of 70
metres from the barrage axis. The bed width of the head race channel is 23 metres. The
head race channel has vertical sides. At 83.0 m downstream of its off-take point of head
race channel (i.e. after crossing the existing left bank main canal alignment), it is
proposed to construct a village road bridge with a width of 6 metres catering to IRC-
Class-I specifications for facilitating the road traffic to the existing barrage and villages
on the right bank of the river.
11.2 INTAKE STRUCTURE
The Intake structure is integral with the upstream face of the power station
structure. The intake structure comprises of a trash rack in the upstream face installed
at an angle of 750 to the horizontal followed by a vertical intake gate. The vertical intake
gate is proposed to be of stop-log type and is to be lowered for facilitating the
maintenance of the turbine and the draft tube.
11.3 TAIL RACE
The tail pool is provided with a reverse bed slope of 1V : 5 H till it meets the bed
level of 65.3 m El of the tail race channel. The width of the tail pool at the exit of draft
tube is 15.0 m, which is same as the combined width of the draft tubes of all the three
units and piers. This splays to 30.0 m in width over a length of 20 metres. The walls of
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the tail pool are warped in both horizontal and vertical. The tail race channel has
trapezoidal section with side slope of 1V: 1.0 H till it meets the Pahumara river, the
length of trapezoidal section is 110.0 metres. The tail race joins the river at a distance of
192 metres downstream of the barrage axis.
**********
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CHAPTER – 12
WATER CONDUCTOR SYSTEM
Water conductor system consists of head race channel, head regulator bridge,
forebay, Intake, power house, draft tubes, tail pool and tail race channel.
1.0 HEAD RACE CHANNEL
As per the surveyed site plan the length of HRC is 43.4 m, with a bed slope of
0.1 in; 43.4 m length, the channel is 9.5 m wide with 5.0 m depth of water.
1.1 Max discharge to be taken by two machines for
Generation of power = 49.7 cumecs
Area of flow = 9.5 x 5.0
= 47.5 sq.m
Velocity of flow
= 1.05 m/sec.
Velocity head =
2.0 Head Regulator
Width of HRC is 9.5 m; at chainage 33 m of HRC, 1.5 m wide pier has been
provided, so there are two bays, each 4.0 m wide and are provided with 5.3 m high
gates and gates hoist arrangement. In case of repair of forebay or P.H, the flow can be
controlled by these gates. Upstream of the gates, coarse trash rock is also provided to
check entry of wooden logs etc. into channel.
3.0 Forebay
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Within the available space and considering he economic aspect the layout of
scheme has been proposed so that it may have 350 m3 of water above MDDL.
Because head race channel is not so long and it is also connected with barrage
pond, so there would not be any difficulty to get water for generation. The width
of forebay is 15.0 m with a sloppy bed, length of forebay including its upstream
transition is 25 m.
4.0 Trash Rack at Intake
Inclined trash rack at intake has been provided at an angle of 700, to stop the
entry of trash etc. to the turbine. The height of opening at trash rack is 5.0 m and
the width of trash rack in each bay is 3.0 m.
No. of bays / openings = 4
Width of opening = 3.0 m
Height of opening / length of inclined trash rack = 5.0 m
through which water will flow
velocity through trash rack =
at trash rack
Velocity head =
5. Entrance Opening to Power House
No. of bays / openings = 4
Width of opening = 3.0 m
Height of opening = 2.8 m
Area of opening for one machine = 2 x 3.0 x 2.8 = 16.8 sq.m.
Area of opening for two machines = 2 x 16.8 = 33.6 sq.m
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velocity of flow at entrance =
Velocity head =
6. Tail Race Channel
Width of channel = 30.0 m
Side slopes = 1.5 H : IV (Boulder pitched)
Mannings coefficient = 0.0225
Longitudinal slope S =
(0.1 m in a length of 85 m) = 0.03443
Maximum design discharge = 38.6 cumecs
Let D = depth of flow
With all above parameters D = 1.03 m
and V = 0.67 m/sec
Velocity head =
For other depth of flows an equation has been written and plotted (Fig. 10.6).
7. Head Losses in Water Conductor System
By considering all the head losses and adding them, average h l comes out to be
K. (where velocity V has been taken at entrance) which is approx. 0.03 m
for Q = 38.6 cumecs; similar head losses can be found out for other discharges.*******
CHAPTER 13
DESIGN CRITERIA OF POWER HOUSE AND POWER PLANT
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13.1 STRUCTURAL DESIGN CRITERIA
Intake Structure
The intake structure proposed consists of a rectangular bellmouth behind the
trashrack.
The intake gate is provided in a separate structure. Grooves shall also be
provided in the intake gate structure for stoplogs. The intake gate is proposed to be
operated by electric motor operated hoist from the control room. The gate shall be of
vertical sliding type.
Trashrack
A trashrack fabricated out of mild steel flats and structural numbers at the inlet to
the bellmouth to prevent the entry of large size debris/floating matter. Trash racks (in 3
pieces) shall be erected between the grooves provided at the nose piers on either side
& bay for easy removal from the top. The trash rack shall be installed at an angle of 75 o
to the horizontal.
The racks are provided from the bottom of the intake structure 1.0 above pond
level. The area of the trashracks is sufficient to ensure a minimum velocity of flow or
0.75 m/s with 50% clogging.
Approach to Service Bay
Access to the power house has been proposed along a 5 m wide road on the
right bank of the channel located at an elevation of 50.5 m.
Power House Building
A surface powerhouse has been proposed to be located on the right bank of
river. The size of the building is 10.6 m (along flow) x 23.5 m (across flow) to
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accommodate two units of Kaplan type turbine along with its respective synchronous
generators and control panels. The layout of the various components is shown in Drg.
No. 05 and 06.
Flow to the turbine is to be regulated by wicket gates. Provision for vertical
sliding stop log type intake gates has been made to take care of maintenance
requirements. The power house proposed is of the indoor type, where all erection and
maintenance of machine is done within the power house itself.
Drainage sump, hydraulic power pack and control panel are placed at suitable
locations to minimize the space requirements and the length of the control cables, etc.
Structural Design
The power house design consists of (a) superstructure and (b) substructure. The
components of the superstructure are :
(1) Roof
(2) Roof supports
(3) Brackets for gantry crane rails
(4) Walls
(5) Floors.
The components of the substructure are :
(1) Draft tube top slab
(2) Draft tube bottom slab.
(3) Turbine and generator foundation.
The superstructure is designed to withstand the following loads :
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(a) Dead loads consisting of self weight of the structure and the permanent
superimposed loads.
(b) Live loads for roof and floor according to IS : 4247.
(c) Wind loads conforming to IS : 875.
(d) Crane loads consisting of the weight of fully loaded crane, its impact, crane
surges or crane braking forces.
(e) Earthquake forces according to IS: 1893.
(f) Water pressure, earth pressure wherever applicable.
The permissible stresses for design of superstructure are as per IS:456 for RCC
and IS:800 for structural steel. The same have been increased for various
combinations of loads as laid down in IS: 4247.
Sl. No. Load Combination Increase in stress by % age
1. D.L. + L.L. + moving crane loaded to half its capacity and normal FWL
8
2. D.L. + L.L. + moving crane loaded to half its capacity + temperature + normal TWL + wind load
25
3. D.L. + L.L. + moving crane loaded to full capacity + temperature + normal TWL
25
4. D.L. + L.L. + unloaded standing crane + temperature + max TWL + earthquake
33.3
5. D.L. + L.L. + moving crane loaded to half capacity + temperature + max TWL
33.3
6. D.L. and temporary construction loads 25
The permissible stresses for rivets, bolts, etc. are increased by 25% only in all cases
from Sl.No. 2 to 6.
Roof
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The power house is proposed to be covered by GCI sheets with the sheets fixed
to the roof truss through purlins. A minimum thickness of 1.25 mm is provided.
The GCI sheets conform to IS:277. It is to be placed directly on the purlins and
held in position by hook bolts of 10 mm dia at 400 mm c/c. At joints of two sheets a
minimum overlap of 150 mm is provided. The joints along the sides of the sheets shall
overlap two corrugations and the screws are provided at 300 mm centers. All holes are
to be made through ridges and curved washers are inserted to avoid leakage. At the
eaves, the hook bolts are placed at 250 mm c/c to prevent the lifting of sheets due to
gales.
Roof Supports
The roof is supported on purlins resting on steel trusses. The spacing of trusses
is governed by the considerations of the load on the roof. The truss is analyzed for
loads and permissible stresses.
Gantry Girders
The gantry girders are of RCC embedded in the concrete columns and walls of
the power house. The girders will be supported on brackets projecting from the RCC
columns on the upstream and downstream sides. Suitable base plates are also
provided for fixing the rails on the girders. The gantry girders are designed for worst
combination of moments, shear force and thrust transmitted to them by the crane in the
loaded conditions.
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Substructure
The power house is designed with a raft foundation. The stability analysis is
done considering:
(a) Dead load and bearing pressure
(b) Shear friction factor.
The analysis is done in two directions, longitudinal and transverse. The loads
considered in the design are :
(a) D.L. of the structure including embedded parts,
(b) Main equipment loads, i.e., turbine, generator, valves, etc.,
(c) Crane loads including surges,
(d) Live loads,
(e) Wind loads,
(f) Penstock thrust including water hammer,
(g) Weight of water acting on the substructure, i.e., draft tube.
(h) Pressure due to tail water level.
(i) Uplift pressure,
(j) Pull of conductor if fixed on building, and
(k) Seismic forces.
Generator Floor
The generator floor which is also the top slab of the draft tube is designed to
carry load of machines, live load and any thrust transferred through turbines, generator
or any other machine. Structurally it is designed as a slab constructed on ground level
with opening at draft tube location where it acts as RCC box combined with draft tube
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piers and the base slab. However, it is checked for concentrated loads and thrust of
machine foundation on generator floor.
The drawing of the power house showing general layout and other details are
enclosed as Drawing No. 05 & 06.
Tail Race Channel
The water from the power house after power generation is proposed to be
channelised to join the Pahumara river downstream of the existing barrage through at
tail race channel provided with a suitable slope. The tail race channel is designed to
pass the maximum discharge at the desired full supply level.
13.2 HEAD RACE CHANNEL
An approach channel shall be constructed just upstream of the existing right
bank canal intake and upstream of barrage. The bed width of the proposed head race
channel shall be 9.5 m. To prevent entry of bed load into the approach channel, it is
proposed to construct the bed of channel sufficiently high at the entry into the mouth of
the approach channel. The entry to head race channel shall be so aligned such that a
smooth flow from the river into the approach channel is ensured and the bed load is
directed towards the under-sluices located in the barrage.
The head race channel shall have a rectangular cross section with a width of 9.5
metres. The length of the head race channel is proposed to be 43.4 meters.
13.3 ROAD BRIDGE
The proposed approach channel has to pass under existing road to barrage
requiring a bridge span of about 9.5 m. To keep the same alignment of road the bridge
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is proposed to be constructed on the transition portion of the approach channel to the
power house. The span of the road bridge at centre line shall be of 9.5 m.
13.4 SPILLWAY
In the event of load throw-off or non-availability of machines for power
generation, the excess water has to be passed over the barrage spill ways after meeting
the primary commitment for irrigation in order to maintain the safety of the canal and the
upstream river bank from breaching due to over topping.
13.5 INTAKE STRUCTURE
The intake structure will be provided with a trash rack downstream of which will
be the intake gates. The two number gates will be operated by a hoist provided on the
upstream deck of the power station.
13.6 POWER STATION
13.6.1 CRITERIA FOR SELECTION OF HYDRO TURBINE
General:
The hydro-turbine is the key element in the hydro power station and all the
ratings and dimensions revolve around that of the turbine. Though theoretically , turbine
can be applied at any head , but on considerations of economy ,and the strength of
materials achieved upto that point of time, the use of hydro-turbine is limited in
application to specified range of head.
The basic factors considered in the selection of the turbine is enumerated below:
(1) Availability of the type of turbine for the applicable head,
(2) Standard runner diameters available,
(3) Suitability of the runner diameter to adapt to runner blade angle control on
account of wide variations in head and discharge,
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(4) Standard outputs (frame sizes) for generator,
(5) Easy availability of equipment indigenously, and
(6) Less number of units to economize on cost while not compromising on
reliability.
Type of Turbine
The following types of turbines are suitable for application up to a head of 25
metres.
(a) Axial flow
(b) Cross flow
(c) Mixed flow (Radial axial)
As per IS 12800 (Part 3) :1991 – “Guidelines for Selection of Hydraulic Turbine ,
Preliminary Dimensioning and Layout of Surface Hydroelectric Power Houses- Part 3 :
Small, Mini , Micro Hydroelectric Power Houses” issued by Bureau of Indian Standards,
the head of application for different types of hydro turbines are given in Table 13.1.
Table 13.1: Turbine Performance CharacteristicTurbine Type Application Head
Minimum (in meter) Maximum (in meter)Vertical fixed blade propeller 2 25Vertical adjustable propeller (Kaplan) 16 40Tubular with adjustable blades and fixed wicket gates (Horizontal Kaplan)
2 25
Tubular fixed blade with wicket gates (Horizontal propeller)
(6) Gantry crane 5 tonne capacity for handling intake gate and trash rack
The turbines shall broadly conform to the following specifications :
Turbine :
Number of Turbines : Two
Type of Turbine : Kaplan
Rated Output : 1063 kW
Maximum net head : 7.21 mMinimum net head : 6.315 m
Rated Head : 6.4 metersDiameter of Runner : 2100 mm.
13.6.2 Generator
There are two types of generators namely:
1. Synchronous, and
2. Induction.
Induction generators are generally about 20% cheaper than the synchronous
generators of same output. Whereas synchronous generators are self contained in
developing its own excitation power, induction generators require an external source for
providing it with the magnetization power. The synchronous generators require more
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complicated governing and excitation control systems whereas the induction generators
do not operate and being sturdier require less maintenance, and are ideally suitable for
mini hydroelectric stations where economy in capital cost is of prime concern.
Since the unit size is 1000 KW, it would not be possible for the 11 KV local
system to provide the magnetization power required by the generator. Hence it has
been proposed to use synchronous generators.
The generator shall conform to the following broad specifications:
Type : Synchronous
Number of Units : Two
Rated output : 1250 KVA
Rated Voltage : 3300 V
Number of Phase : Three
Frequency : 50 Hz
Power factor : 0.8 lagging
Synchronous speed : 750 rpm
Continuous overload capacity : 10%
Each generator shall be provided with its individual control and protection
equipment and system which are broadly defined as follows:
(a) Water level control
(b) Protective relays
(c) Neutral grounding resistor and isolating switch.
The generator shall be designed with adequate structural strength to withstand
the runway speed of the turbine i.e. about 2.7 times the rated speed for 30 minutes
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without any damage. The factor of safety at maximum runaway speed of the turbine
based on yield point of material shall not be less than 1.5.
The generator shall be designed to continuously deliver 10% overload capacity
without overheating.
The generator shall be provided with four (04) nos. of embedded temperature
detectors for indicating the stator winding temperature on the generator console.
The generator shall be provided with space heaters of adequate rating to
maintain the temperature of the generator at last 5oC above the ambient and avoid
condensation of moisture.
The generator shall be cooled by axial flow centrifugal fans mounted at each end
of the rotor. The generator shall be provided with screen protected enclosures for open
ventilation.
The stator frame shall be manufactured of cast iron/fabricated steel construction.
The frame shall be designed to withstand the bending stresses and deflections due to
its self weight and the weight of the core supported by it.
The stator core shall be built up by segmental punching made of low loss silicon
sheet steel non-oriented type and end plates. Each punching shall be properly debarred
and applied with insulating varnish on both the sides.
The generator speed has been tentatively suggested to be 750 RPM.
The generator shall be designed to have a noise level not exceeding 90 db at a
distance of one (01) metre from the equipment.
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13.6.3 Flywheel
Necessary flywheel effect shall be incorporated into the rotating parts of the
generator and shall be determined in consultation with the turbine manufacturer to limit
the speed rise and pressure rise within permissible limits. In case requisite moment of
inertia is not available from the rotor, a separate flywheel shall be provided to furnish the
additional flywheel effect required.
13.6.4 Speed Increaser
A single stage speed increaser shall be provided connecting the shafts of the
turbine and the generator.
It is proposed that belt drive used as mode of power transmission as well as
increasing the speed of the turbine to that of the generator. In case suitable belt drive is
not available gear type speed increaser can be used.
In case parallel shaft gear types speed increaser is used, it shall have body
manufactured out of cast iron or fabricated steel. The gear shall be made of suitable
hardened alloy steel of chromium-nickel and molybdenum.
13.6.5 Control System & Oil Pressure Unit
The turbine is proposed to have moveable guide vanes to help in switching on
the generator to the system exactly at the synchronous speed.
The guide vanes as well as the adjustable runner blades are proposed to opened
by hydraulically operated servomotor and held in desired position by oil pressure. In the
event of load throw off or when actuated by master tripping relay due to fault or under
command to shut down (normal or emergency), the oil pressure is released by the
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actuation of DC operated solenoid valve and the guide vanes close under counter
weight provided.
An oil pressure unit (OPU) proposed to be provided for the purpose. The OPU
shall be provided with an electrically operated pump and a manual pump. The pressure
in the system shall be continuously maintained at the desired pressure level within a
very narrow band. In the event of pressure falling by say about 5% the electrically
operated pumping shall start to build up the pressure again. Pressure switches shall be
therefore provided for starting the pump (on falling pressure) and stopping the pump (on
reaching set pressure) automatically.
The oil pressure unit shall also be used to operate the runner blades.
13.6.6 Generator Control Board
There shall be one control panel for each of the turbines and the generators
fabricated out of 2 mm thick mild sheet steel. It shall be free standing type with single
front design. The control panel shall be mounted on antivibration pads. The board shall
be applied with synthetic enamel paint on antirust primer after being subjected to sand
blasting and acid pickling.
Each generator cubicle shall contain the following:
- Surge diverter – 3 nos.
- Surge capacitor – 3 nos. with built-in discharge resistor
- Panel space heater with thermostat – 1 no.
- Panel illumination lamp with switch – 1 no.
- Cast resin type current transformer – 3 nos.
- Cast resin dry type double secondary single phase potential transformer – 3 nos.
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- 1200 Amps 415 V, 3 phase, 3 pole, electrically operated drawout type air breaker
with thermo-magnetic release, shunt trip coil under voltage release, auxiliary
contact, 50 KA- - One no.
- Protective relays comprising of the following :
- Voltage restrained over current (IDMT) relays - 2 nos.
- Earth fault relay - 1 no.
- Over voltage relay - 1 no.
- Under voltage relay - 1 no.
- Generator stator earth fault relay - 1 no.
- Auxiliary relay (Master relay) - 1 no.
- Measuring & Indicating instruments comprising of the following :
- Voltmeter with selector switch - 1 no.(R – Y – B - 0)
- Ammeter With selector switch - 1 no.(R – Y – B - 0)
- Kilowatt meter - 1 no.
- Kilovar meter - 1 no.
- Power factor -1 no.
- Frequency meter - 1 no.
- Speed indicator - 1 no.
- Temperature indicator – 6 point for stator temp. - 1 no.
- Kilowatt hour meter – 3 phase balanced/unbalanced - 1 set
- Indicating lamps for breaker on/off - 1 set
- Controls comprising of the following :
- Start control switch with relays - 1 set
- Stop, control switch with relay - 1 set
- Twelve point annunciation facia comprising of the following :
- Oil pressure unit high / low
- Generator winding temperature high
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- Machine shutdown under fault
- D.C. failure
- Cooling water failure to bearing of generator/turbine/generator/shaft seal.
One set of acknowledge, reset and test push buttons
One hooter and blinking relay.
13.6.7 PLC System
It is proposed to provide a programmable logic controller for the following
functions :
- Start/stop of the turbine and generator.
- Monitoring of the temperature inputs from RTD’s.
- Monitoring of the alarm inputs from the turbine and generator protection system.
There shall be also inputs through suitable transducers for monitoring the
following parameters and recording the same.
- Generator KW
- Generator KWH
- Generator current
- Generator voltage
- Frequency
- Power factor
- Trivector meter.
The system shall be provided with independent CPU, MEMORY and POWER
SUPPLY so that failure of one system shall not affect the operation of other system(s).
The system shall have self-checking and self-diagnostic features for all internal
faults and shall be capable of isolating the defective sub-system.
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The system should be suitable for continuously operating without air conditioner
in the power plant environment with temperature upto 45o C and high humidity.
13.6.8 Local Instrumentation
The following instruments shall be mounted locally :
(1) Rotameter to check flow of cooling and sealing water to the bearings, gearbox,
stuffing box as required.
(2) Turbine and gearbox (if provided) bearing temperature.
(3) Oil pressure gauge of the oil pressure unit.
13.6.9 Station Auxiliary Power Board
This board shall also be of single front design conforming to the same
manufacturing standards and dimensions as the unit control board. This power
distribution board shall cater to various auxiliary power requirements in the station.
The power supply to the board shall be obtained from the spillway gate control
room due to its higher reliability. The board shall house the following :
- Incoming 100 Amps MCCB - 1 no.
- Voltmeter with selector switch - 1 no.
- Ammeter with selector switch - 1 no.
- KWhrs meter with CTs - 1 no.
- Aluminium Busbar 4 wire-100 Amps - 1 set
- MCBs with HRC fuses 25 Amps on feeders - 7 nos.
- MCBs with HRC fuses 16 Amps on feeders - 8 nos.
- Terminal blocks for 12 feeder circuits - 15 nos.
13.6.10 Telephone System
One telephone connection shall be provided in the power station from the local
Department of Telecommunication Network.
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13.6.11 Station Drainage System
Since the level of the bottom most floor is below the tail water level, there is
likelihood of seepage water entering into the power station. Besides there is likelihood
of leakage water from gland packing etc.
It is proposed to provide a drain of 250 mm x 250 mm around the outer walls of
the power station entering into a drainage sump whose floor level is fixed at
31.6 m.
It is proposed to install two (02) nos. of sump pumps discharging into the tail race
above the maximum tail water level.
The pumps would be of self priming mono-block type. The motors will be rated at
415 volts, three phase.
13.6.12 Dewatering System
It is proposed to dewater the draft tube by one number portable centrifugal pump
of submersible type. For the purpose of dewatering of the draft tube, a 750 mm dia
opening has been provided on the draft tube deck. The dewatering opening shall be
closed by suitable mild steel cover with bolting facility and shall be flush with the floor
level.
A submersible pump drive by a 6 HP AC three phase, 415 volts motor is
considered to be adequate for the purpose.
13.6.13 Lighting System
The indoor lighting shall comprise of twenty four (24) numbers of twin 40 watt
lamps in industrial type fittings.
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Besides there will be ten (10) number of 60 watts incandescent lamps distributed
around the power station to form the D.C. emergency lighting systems. These lamps will
be connected to the DC system through a suitable inverter 110 Vdc/230 VAC.
The outdoor lighting is proposed to comprise of 8 nos. of 250 watt sodium vapour
lamps mounted on the powerhouse walls – two on each face to illuminate the
transformer yard the draft tube deck, the approach road and the spillway area.
13.6.14 Ventilation System
It is proposed to install six (06) nos. of exhaust fans of 300 m size, 1000 RPM
mounted at a suitable elevation facing towards the tail race.
13.6.15 D.C. System
To meet the requirements of operation under emergency conditions it is
proposed to install a D.C. Battery lead-acid type rated at 120 Ampere-hours, 110 volts.
The cells shall be of tubular positive plate with polypropylene plastic or hard rubber
container.
A suitable battery charger is proposed to be provided to meet the trickle charge
as well as boost charge requirements of the DC battery.
A DC control board is proposed to be provided made out of 2 mm sheet steel of
wall mounting type housing the following :
(1) Four feeder circuits with MCCBs of 10 AMPs each.
(2) Earth leakage indication
(3) Battery healthy condition indication
(4) 0 – 20 amps DC ammeter
(5) 0 – 60 volts DC voltmeter
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(6) Trip and indication fuses
(7) Charger on-off indication
(8) Battery incoming MCCB-20 AMPs.
13.6.16 Station Grounding
Station grounding is proposed to comprise of a suitable earth-mat buried at the
foundation level below the raft. From the grounding mat, six (06) nos. of risers shall
brought upto the machine hall floor. The risers as well as the ground mat shall be made
of mild steel strips with corrosion protection as per standard practice. The risers shall be
of 50 mm x 6 mm mild steel strips.
The earthing of the frames and the neutral shall be as per the relevant provisions
of the Indian Electricity Rules and Indian Standards Specification.
13.6.17 Fire Fighting
It is proposed to provide the following types of portable fire extinguishers :
(1) Dry chemical type fire extinguisher 4 kg capacity - 10 nos(2) Foam type fire extinguisher - 4 nos.
13.6.18 Power House Crane
It is proposed to provide a girder type hand operated crane with a capacity of 15
tons. The hoisting operation shall be done by electric motor operated hoist, which can
be operated from the generator floor level. The HOT crane would facilitate a small group
of erection and maintenance personnel to handle both erection and maintenance
activities.
13.6.19 Draft Tube Gate
Two numbers stop log type gates are proposed as the draft tube gate for each
unit for facilitating maintenance of the turbine.
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The gates shall be operated from a gantry girder provided for the purpose on the
draft tube deck. The lifting and lowering operations shall be possible with a chain pulley
block of requisite capacity.
The gate shall be provided with a suitable lifting beam with grab-clamps.
13.7 TAILRACE CHANNEL
The tail race channel will connect the draft tubes of the power house with the
Pahumara River. The section of the channel would be trapezoidal with a bed width of
30 m. The length of the Tail race channel would be 85 m.
13.8 AUXILIARY POWER SYSTEM
To meet the auxiliary power requirements of the power station, it is proposed to
install one 125 KVA, 3300 /433 V transformer tapped from the 3.3 KV generator bus.
13.9 POWER EVACUATION
It is proposed to install one no. of step-up transformer rated at 2500 KVA, 3.3 /11
KV. The transformers shall be plinth-mounted.
From the high voltage side a single circuit 11 KV overhead line shall be erected
upto the existing 11 KV line near the barrage.
The power is to be evacuated through the existing 11 KV single circuit line upto
the Pahumara barrage site.
**********
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CHAPTER – 14
ABSTRACT OF COST ESTIMATES.
No.ITEM
AMOUNTREMARK
CIVIL E/M TOTAL(1) (2) (3) (4) (5) (6)
I Works 1. A-Preliminary 75.00 75.00 2 B-Land 2.00 2.00 3. C-Works 3.1 Head Race Channel 47.42 Annex. C-1 3.2 Regulator & Bridge 60.43 Annex. C-2 3.3 Forebay 47.96 Annex. C-3 3.4 Intake & Power Station Structure 319.66 Annex. C-4 3.5 Tail Pool & Tailrace Channel 109.77 Annex. C-5 Total C-Works 585.24 585.24 4. K-Building 25.00 25.00 5. M-Plantation 0.50 0.50 6. O-Miscellaneous 15.00 15.00 7. P-Maintenance @ 1% of items C-works & K-buildings 6.10 6.10 8. Q-Special tools & plants 4.00 4.00 9. R-Communication 20.00 20.00 10. S-Power Plant & Accessories 600.00 6000.00 11. Y-Losses on stock @ 0.25% on item 3 to 7 & 9 to 10 1.64 1.64 Total : I – works 734.48 600.00 1334.46 II ESTABLISHMENT @ 4% of I-Works 29.38 24.00 53.38
III ORDINARY TOOLS & PLANTS @ 0.5% of I-Works 3.67 3.00 6.67
IV RECEIPT & RECOVERIES At the rate of 75% of Q-spl. T&P -15.00 -15.00 Total of Direct Charges 1379.53 V INDIRECT CHARGES 1. Audit & Account @ 1% of I-Works 7.35 6.00 13.35 VI TRANSMISSION SYSTEM
1.Strengthening of the existing 11KV Single circuit line upto 33/11 KV Substation at Sarupeta (15 kms) . 20.00 20.00
GRAND TOTAL 759.88 653.00 1413.88
**********
EXPLANATORY NOTES ON COSTS ESTIMATES
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In the following paragraphs explanatory notes on cost estimates of various items
of work are stated:
1. A-Preliminary: In this estimate, the expenditure on investigations like
reconnaissance survey, topographical survey, geological and geotechnical
investigations are included. The cost estimates also include the expenditure
on preparation of detailed project report and also the expenditure likely to be
incurred on detailed design, tendering and tender evaluation etc. Expenditure
on this account is estimated at Rs. 75.00 lacs.
2. B-Land: The land required for the proposed power plant including the
appurtenant works are within the government owned land. It is therefore
presumed that the project activity being an activity aimed at economic and
social development of the un-developed area around the project, the land
required shall be transferred to the project developer at no-cost. However, a
token amount of Rs. 2,00,000.00 is provided for meeting any likely
eventuality.
3. C-Works: The estimates for the following works have been included:
(i) approach channel, (ii) head regulator for approach channel and coarse
screening, (iii) intake and power station structure and (iv) tail-race. The cost
estimates have been based on the designs prepared for each of the
structures and the schedule of rates of Public Works Department of Assam
Government with due consideration towards lead distances for steel, cement,
coarse and fine aggregates and other materials and cost escalation.
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A bridge is to be constructed across the head race channel. To prevent
entry of trash, logs and other foreign materials to the forebay, it is proposed to
provide a coarse trash rack in front of the bridge structure. It is also proposed
to provide two vertical lift gates operated by a gate hoist so that the approach
channel to the forebay could be closed whenever necessary so as to facilitate
cleaning of the channel as well as the forebay. The cost estimates for the
RCC bridge of 10 m long and 6 m wide complying to IRC Class-A and the
cost of the structure for the coarse track rack and the gate hoist and a 1 m
wide operating platform is Rs. 60.43 lakhs (Annexure C-2). The cost of the
head race channel is estimated at Rs. 47.42 lakhs (Annex.C-1); that of
forebay is Rs. 47.96 lakhs (Annex-C3); that for intake and power station
structures is Rs. 319.66 lakhs (Annex-C-4) and that for tail pool and tail race
channel is Rs. 109.77 lakhs (Annex-C). The total cost of civil works is
estimated at Rs.585.24 lakhs.
4. K-Building: The cost for temporary buildings and residential buildings for the
operating staff has been estimated at Rs. 25,00,000/- and including in the
budget estimates.
5. M-Plantation: A sum of Rs. 50,000/- has been provided for plantation in the
project area. Since the project area is very small, the expenditure proposed is
considered adequate.
6. O-Miscellaneous: For miscellaneous expenditures for which no specific item-
wise cost could not be estimated, an expenditure estimated at Rs. 15 lakhs
has been provided for.
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7. P-Maintenance: A provision for expenditure @ 1% of the estimated cost for
C-Works and K-Buildings is proposed to meet the maintenance of these
works during the construction period which is in line with the prescribed
norms of the Central Electricity Authority.
8. Q-Special Tools & Plants: A provision for expenditure amounting to Rs.
20,00,000/- has been provided for special tools and plants like: concrete
mixtures, pneumatic vibrators, portable air-compressors etc. However, since
the works is to be executed through the contractors, expenditure on this head
shall be included by the contractor in the civil works estimates.
9. R-Communications: A provision of Rs. 4,00,000/- has been made in the cost
estimates to meet the probable expenditure on construction of connecting
road from the PWD road upto the power plant entry.
Under this head expenditure on telephone connections to the project
office is also included.
10. S-Power Plant and Accessories: A provision of Rs. 600,00,000/- has been
made in the cost estimates towards design, engineering, manufacture, supply
(including transport upto the project site), handling, erection, commissioning
and testing of two units of 1000 KW turbine and generating units along with
all auxiliary equipment including the cost of 2500 KVA step-up transformer
and 11 KV switchyard with circuit breaker, isolators, and earthing system etc.
The cost estimates are based on budgetary prices receive from a few reputed
indigenous manufacturers and suppliers of similar equipment.
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11. Y-Losses on Stock: In accordance with the prescribed norms of framing
estimates for hydro power projects towards losses on stock @ 0.25% on C-
works, K-buildings, O-miscellaneous, Q-special tools and plants, R-
communication and S-power plant accessories has been provided for.
12. Establishment: Towards expenditure on establishment for supervising the
construction, a provision @ 4% of I-works has been made in the cost
estimates which is in tune with the practice adopted by private power
producers.
13. Ordinary Tools and Plants: A provision has been made @ 0.5% of the I-
works towards the cost of ordinary tools and plants in line with the prescribed
norms by Central Electricity Authority (CEA).
14. Receipts and Recoveries: In accordance with prescribed norms, 75% of the
cost of tools and plants has been provided for under this head amounting to
Rs. 15,00,000/- This is based on the assumptions that on the completion of
the construction of the project, the special tools and plants procured for the
project shall be disposed off at a depreciated cost.
15. Indirect Charges – Audit and Accounts: In accordance with the prescribed
norms of Central Electricity Authority, a provision towards expenditure on
audit and accounts @ 1% of I-works has been provided for.
16. Transmission System: The power is to be evacuated through the existing 11
KV single circuit line upto the Pahumara barrage site. There is an existing 11
KV line upto the barrage site from the 33 x 11 KV, 2 x 5 MVA Pathsala Sub-
station. The length of the existing line is approximately 30 kms. It is
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understood that a 33 x 11 KV sub-station with a capacity of 1 x 2.5 MVA has
been proposed at Sarupeta which is located at a distance of 15 kms. from
the proposed SHP. It is understood that the 11 KV line from Pathsala has a
connected load of about 500 KVA. It is proposed that the existing 11 KV line
shall be strengthened by changing the conductor to ACSR Weasel. On this
account an expenditure estimated at Rs. 20,00,000/- has been provided for in
the cost estimates.
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Annex. C-1
COST ESTIMATE FOR HRC
Sl. No. ITEM OF WORK QTY UNIT RATE, Rs AMOUNT, Rs
1 Excavation 8947.20 cum 74.13 663,256
2 EW in filling in forebay 2236.80 cum 41.58 93,006.14
3 CC 1:4:8 253.80 cum 2338.17 593,427.55
4 CC M15 251.20 cum 3434.20 862,671.04
5 Stone Masonry 1225.00 cum 2016.00 2,469,600.00
6 Shuttering 384.00 sqm 156.85 60,230.40
TOTAL 4,742,191.07
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Annex. C-2
COST ESTIMATE FOR RAGULATOR & BRIDGE
Sl. No. ITEM OF WORK QTY UNIT RATE, Rs AMOUNT, Rs
1 Excavation 100.00 cum 74.13 7,413.00
2 EW in filling 25.00 cum 41.58 1,039.50
3 CC M15 100.00 cum 3434.20 343,420.00
4CC M20 in deck slab, raft slab & piers 176.80 cum 3878.08 685,644.54
5
Steel Reinforcement (Fe 415)
in M20 concrete15.27 MT 36379.35 555,391.90
6 M S Coarse Screen 38.70 sqm 15000.00 580,500.00
7
MS gates including hoisting
arrangement38.70 sqm 100000.00 3,870,000.00
TOTAL 6,043,408.94
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Annex. C-3
COST ESTIMATE FOR FOREBAY
Sl. No. ITEM OF WORK QTY UNIT RATE, Rs AMOUNT, Rs
1 Excavation 7261.50 cum 74.13 538,295
2 EW in filling in forebay 1815.38 cum 41.58 75,483.29
3 CC 1:4:8 204.30 cum 2338.17 477,688.13
4 CC M15 317.64 cum 3434.20 1,090,839.29
5 Stone Masonry 1235.72 cum 2016.00 2,491,211.52
6 Shuttering 784.00 sqm 156.85 122,970.40
TOTAL 4,796,487.63
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Annex. C-4
COST ESTIMATE FOR INTAKE & POWER HOUSE
Sl. No. ITEM OF WORK QTY UNIT RATE, Rs AMOUNT, Rs1 Excavation 12612.00 cum 74.13 934,927.562 EW in filling near runner chamber 3153.00 cum 41.58 131,101.74
3CC 1:4:8 in base course for raft below turbine chamber
110.00 cum 2338.17 257,198.70
4 CC M20 2695.00 cum 3878.08 10,451,425.605 CC M20 in superstructure 248.00 cum 3878.08 961,763.846 B/W in PH Walls 168.70 cum 2763.60 466,219.327 Dewatering LS 500,000.008 Steel Reinforcement (Fe 415) in M20 168.40 MT 36379.35 6,126,359.85
9M S intake gates including hoisting arrangement
48.00 sqm 100000.00 4,800,000.00
10 M S trash rack 50.00 sqm 35000.00 1,750,000.0011 Draft tube gates & hoist 56.00 sqm 100000.00 5,600,000.0012 P/F pressed steel door frames
The cost of the project is estimated at Rs. 1413.00 lakhs and cost including
escalation and interest during the construction is Rs. 1566.33 lakhs. The per kilowatt
cost is Rs. 7.832 crores per MW. The cumulative cash accrual at the end of 35 – year
operating period is Rs. 4269.35 lakhs on an equity of Rs. 437.93 lakhs which is 9.75
times the equity.
The project benefits do not include the carbon credit i.e. likely to be available
under “Clean Development Mechanism (CDM)” which will enhance the profitability of
the project. The equivalent carbon dioxide remission shall be 8,750 tonnes per annum
which shall qualify for CO2 trading under CDM regime. With a notional trading value of
US $ 12 per tonne of carbon, additional annual revenue on this account is estimated at
Rs. 52,50,000.00 (assuming US $ 1 = Indian Rupees 50).
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It is also to point out that the financial evaluation has been made on the basis of
escalation in cost of operation and maintenance @ 4% per annum whereas the sale
rate of energy has been considered constant at Rs. 3.20 per kwh for all the 35 – years
which is unlikely to happen due to inflation and depreciation in the value of rupee. In the
event of increase in cost of generation, the profitability of the project shall further
improve.
********
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Annexure 15.1
INPUT DATA SHEET
Total Project Cost Rs. 1413.00 lacs Cost of land Rs. 2.00 lacsPreliminary Development works Rs. 75.00 lacsEstimated cost of Civil work Rs. 683.00 lacsEstimated cost of E/M works including Rs. 653.00 lacstransmission works Escalation in cost per year 5%Construction period (proposed in year) 2 years
Phasing of expenditure Ist Year 30%IInd Year 70%
Energy (i) Generated in 90% dependable year 7.214 x 106 Kwh
Less 5% towards forced outage 0.36 x 106 kwhAuxiliary consumption @0.5%Loss during transformation @ 0.5% 0.072 x 106 kwhNet available energy for sale 6.782 x 106 Kwh
(ii) Water cess to the state @ 0.05 paise/unit 3.39 laks
(iii) Generated on average in a year 9.34 x 106 kwhLess 5% towards forced outage 0.467 x 106 kwhAuxiliary consumption @ 0.5%Loss during transformation @ 0.5% 0.088 x 106 kwhNet available energy 8.784 x 106 kwh
DepreciationSalvage value 10%Depreciation has been calculated on an useful life span of 35 years by straight line method.
Interest rate Interest rate on term loan 10%Interest rate on working capital 11%Period of repayment of term loan (in years) 10 years
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128.
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129.
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130.
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131.
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132.
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133.
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CHAPTER – 16
FINANCING OF THE PROJECT THROUGH CLEAN DEVELOPMENT MECHANISM
16.1 INTRODUCTION
Gases like carbon dioxide, nitrous oxide, methane etc. are termed as green
house gases (GHGs) as they absorb and re-emit some of the infrared radiation warming
the earth’s surface and the atmosphere. Any change in the quantity of these gases in
the earth’s atmosphere can change the earth’s temperature and climate. Between 1860
AD and 2000AD, the average global surface temperature has increased by about 0.30C
to 0.60C. The warming has been significant since 1970. The warming is more prominent
in the continental land mass lying between 400 N and 700 N. the increase in
concentration of green house gases in the atmosphere has been attributed to the
human activities like burning of fossil fuels, deforestation, agricultural practices and
manufacturing of industrial products. The enhanced green house effect are likely to
change precipitation patterns, increase in frequency and intensity of storms, hurricanes,
change in vegetation and rise in sea level. Developing countries especially the poor
ones are more vulnerable to these changes due to their high dependence on natural
resources and their limited capacity – human, financial and institutional – to adapt to
extreme events. Climate changes can also affect the health and the livelihood of the
poor adversely. Extreme climate conditions accentuated by green house effect are likely
to cause diversion of scarce resources from poverty reduction to disaster recovery.
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Keeping in view the adverse effects of the increase in green house gas
emissions to the atmosphere, the developed countries and economies in transition
(referred to as Annexure B countries as they are listed in Annexure B of the Kyoto
Protocol) at the Third Conference of the Parties of the United Nations Framework
Convention on Climate Change (UNFCC) in Kyoto, agreed to reduce the GHG
emissions. This agreement is known globally as the Kyoto Protocol.
The Kyoto Protocol outlines a framework for three cooperative implementation
mechanisms: joint implementation, CDM, and emissions trading. Of the three
mechanisms CDM is the only one in which developing countries can participate.
16.2 CLEAN DEVELOPMENT MECHANISM
The CDM is a financing instrument defined in Article 12 of the Kyoto Protocol. A
project in a developing country that reduces GHG emissions, relative to a baseline
project, generates emissions reduction (ER), CDM enables the project owner to sell the
ER credits, once they are certified, to an interested buyer. The project owner or seller
may be a DMC government or a DMC-based company and the buyer could be an
Annex. B country or an Annex B-based company with responsibility to reduce emissions
at home or through the Kyoto mechanisms or any company that might be interested in
buying emission credits for investment, resale, or enhancement of its green image. The
benefits of CDM for the developing country are new financial resources, better
technology, and achievement of its sustainable development objectives, while the
benefit for developed countries is access to less expensive ER opportunities in a
developing country. As emissions have the same global effect irrespective of their
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geographical origin, CDM provides a cost-effective way of addressing the adverse
effects of global warming.
A CDM project produces a new commodity, ER credits, which can be traded to
generate revenue for the project owner. However, as the ER credits are invisible and
intangible, their existence needs to be established and verified. For example, a small
hydro power station generates electricity without emissions of GHGs, while an
alternative thermal power plant (base line) would have produced GHG emissions. The
avoided emissions or ER credits once quantified and verified by independent
operational entities and certified by the CDM Executive Board have a financial value
and can be sold to generate a revenue stream for the project owner. The CDM project
would normally also result in improved local environmental conditions and lowering of
pollution – related health problems compared with the baseline. The CDM facility works
with projects aimed at both sustainable development benefits and GHG mitigation.
These include:
Renewable energy
Energy efficiency
Sustainable agriculture
Forestry.
16.3 THE CDM PROCESS
The CDM process is quite complex and includes five major steps as follows:
(i) Project Identification: the CDM facility will assist the operations departments
to undertake a preliminary assessment of projects and identify projects with
GHG abatement potential. Necessary government or other clearances will be
obtained to proceed further. If the seller is interested in the CDM project
activity, a brief project identification note will be prepared. Next, potential
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buyers will be invited to express interest in offering a commitment to pay for
the development costs of the CDM and for purchasing an agreed quantity of
ERs. Alternatively, the seller might want to pay for the development costs of
the CDM and later approach buyers.
(ii) Project development : The second step relates to project development. This
entails demonstrating and estimating the GHG abatement potential of the
project using an appropriate baseline, developing a monitoring and
verification plan that will be implemented during the operation of the project to
determine actual ER credits generated by the project, and development of the
project design document.
(iii) Validation and registration : The project design document developed in (ii) is
validated by an independent accredited entity or designated operational entity
and submitted for registration to the CDM Executive Board.
(iv) Monitoring verification, and certification of ER credits : During the operation of
the project, the ERs generated are measured according to the monitoring and
verification plan and verified by an independent and accredited designated
operational entity.
(v) Issuance of ER credits: The CDM Executive Board certifies the verified ERs
that can be transferred to the buyer in case of an existing purchase
agreement or traded in the ER market at prevailing prices.
The CDM process is explained through the flow chart enclosed as Annexure-16.1.
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16.4 CARBON DIOXIDE EMISSION REDUCTION FROM PAHUMARA SHP
From the report of the International Agency, “Benign Energy” The Environmental
Implications of Renewables” (1998) the Life Cycle Emission from various energy
sources are reproduced below:
Energy sources
Green House Gas Emission
CO2
G/kwh
SO2
g/kwh
NOx
g/kwh
Coal (best practice) 955 11.8 4.3
Coal (NO2)& FGD 987 1.5 2.9
Oil (best practice) 818 14.2 4.0
Natural gas (CCGT) 430 - 0.5
Small Hydro 9 0.03 0.07
Large Hydro 3.6 – 11.6 0.009 – 0.024 0.003-0.006
It is estimated the annual energy production from the Pahumara SHP shall be
8.873 x 106 on KWh and the energy available for sale be of the order of 8.784 x 106
kwhr per annum. The coal being used in the thermal power stations in India not being of
very good quality, it may be appropriate to assume that the carbon dioxide being
emitted shall be of the order of 987 gms per kwh. On this basis the carbon dioxide
emission reduced by generating same amount of electrical energy from Pahumara SHP
works out to 8750 tonnes per annum. On this basis over the life time of power plant the
carbon dioxide reduction is expected to be of the order 306500 MT. Since the
Pahumara SHP is a renewable energy project and its operation can provide energy for
social and sustainable development without contributing to GHG emissions is eligible for
financing under CDM facility as envisaged in Article 12 of the Kyoto Protocol.
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PAHUMARA - SHP
16.5 Benefits from MNES
The Ministry of Non Conventional Energy Sources (MNES), Govt. of India, provides
a one time subsidy to improve the economic viability of Small Hydro Electric Projects
up to 25 MW installed capacity under certain eligibity criteria. The subsidy is
generally calculated in accordance with the following formula in the North Eastern
Region
Subsidy = Rs. 2.25 cores X C 0.646
Where C stands for capacity of the project in MW.
Since the installed capacity of the project is 2.0 MW, the likely amount of one time
subsidy may be about Rs. 3.52 cores
******
139.
PAHUMARA - SHP
ACKNOWLEDGEMENT
140.
PAHUMARA - SHP
The Detailed Project Report for the proposed Pahumara Small Hydroelectric
Project, (2 x 1000 KW capacity) has been prepared under the sponsorship of
Infrastructure Leasing & Financial Services Limited. The contributors to this report
acknowledge gratefully the support and help extended by Sri D.K. Mittal, Managing
Director, IIDC Sri G.K. Pharlia, Advisor and Sri Pradeep Agrawal, Senior Manager
without whose encouragement and cooperation this report could not have been
prepared.
The authors also acknowledge the technical support provided by Sri D.K.
Agarwal, Retired Engineer-in-Chief, and Sri G.P.S. Bhati, Retired Executive Engineer,
U.P. Irrigation Department in preparation of this report.
This work has been undertaken as a part of the institute’s forward looking policy
towards establishing a coherent industry – institute partnership with a view to furthering
the national development activity.
Devadutta Das Principal Investigator and
Professor, Department of Water Resources Development & Management,
CoordinatorScience and Technology Entrepreneurship Park
Indian Institute of Technology, RoorkeeTelephone No. 01332: 285774 (O), 285822 (O), 285773 (R)
Fax No. 01332 – 285774, 273967
141.
PAHUMARA - SHP
CONTENTS
CHAPTERS DESCRIPTION PAGE NO.
ACKNOWLEDGEMENT (i)
Section-I Executive Summary 1-4
Section-II Salient Features 5-7
Section-III Check List 8-10
Section-IV PROJECT REPORT
1 SCOPE OF THE PROJECT 11-19
2. INTRODUCTION 20-31
3. SURVEYS AND INVESTIGATIONS 32-34
4. WATER RESOURCES (HYDROLOGY) 35-44
5. GEOLOGY 45-58
6. CONSTRUCTION MATERIALS 59
7. PROJECT PURPOSES 60
8. CONSTRUCTION PROGRAMME 61-65
9. ENVIRONMENTAL AND ECOLOGICAL ASPECTS 66-67
10. WATER AND POWER STUDIES 68-79
11. INTAKE AND TAIL RACE WORK 80-81
12. WATER CONDUCTOR SYSTEM 82-84
13 DESIGN CRITERIA OF MAJOR COMPONENTS OF SCHEME
85-109
14 ESTIMATES OF COSTS 110-120
15 FINANCIAL ASPECTS 121-133
16. FINANCING OF THE PROJECT THROUGH CLEAN DEVELOPMENT MECHANISM
134-139
ANNEXURES 140-163
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PAHUMARA - SHP
LIST OF ABBREVIATIONS
AC Alternating currentACSR Aluminium conductor steel reinforcedAh Ampere-hourAERC Assam Electricity Regulatory Commission ASEB Assam State Electricity Board AVR Automatic voltage regulatorBCR Benefit/cost ratioBTC Bodo Land Territorial Councilc/c Center to centerCB Circuit breakerCEA Central Electricity AuthorityCh Chainagecm/s Centimeter per secondCumec Cubic metre per secondCWC Central Water CommissionDC Direct currentDG Diesel generatorDia DiameterDSCR Debt Service Coverage RatioDPR Detailed Project ReportDSI Detailed Surveys & InvestigationsE&M Electro-MechanicalFRL Full Reservoir levelFSL Full Supply Level FY Financial yearGI Galvanised IronGOI Government of IndiaGRP Glass Reinforced Polyester GWh Giga Watt hour (one million unit of power)HDPE High Density PolyethyleneHFL High Flood LevelHGL Hydraulic Grade LineHV High VoltageHz HertzICR Interest Coverage RatioID Internal diameterIDC Interest During ConstructionIL&FS Infrastructure Leasing and Financial Services LimitedINR Indian National RupeeIREDA Indian Renewable Energy Development AgencyKg KilogramKm Kilo-meterkN Kilo-Newton
m2 Square metreM20 Concrete of characteristic strength 20 N/mm2
M25 Concrete of characteristic strength 25 N/mm2
m3/s Cubic metre per secondmA Milli-ampmasl Meters above sea levelmin Minutemm Millimeter MAT Minimum Alternate Tax MDDL Minimum Draw Down Level MNES Ministry of Non-Conventional Energy and Sources Ltd.MoU Memorandum of Understandingmsl Mean Sea LevelMVAr Mega-Volt-Ampere reactiveMW Mega-WattMWL Maximum Water Level No. NumberNPV Net Present ValueNWL Normal Water LevelO&M Operation & MaintenanceOD Outside DiameterOGL Original Ground LevelPLC Programmable Logic ControllerPMG Permanent Magnet GeneratorPPA Power Purchase AgreementR RadiusRC Run-of-riverrpm Revolutions per minuteRs Indian rupeesSCADA System Control and Data AcquisitionSHP Small Hydropower ProjectTWL Tail Water level V VoltV:H Vertical to HorizontalVAT Value Added TaxYr Year
144.
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LIST OF DRAWINGS
LIST OF DRAWINGS
Sl.
No.Title of Drawings Drg. No.
1. Layout Plan of Scheme marked on Contour Map 01
2. Layout of Project 02
3. Plan of Power House 03
4. Cross-Section of Power House 04
5. Head Race Channel – Plan & Sections 05
6. Tail Pool & Tail Race Channel – Plan & Sections 06
7. Main Electrical Single Line Diagram 07
8. Switch Yard 08
9. Land Area Required for the Scheme 09
10. Topographic Survey of Scheme 10
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ANNEXURESA1-6, B1-6, C1-6, D1-6
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Table 5.2 : Plate Load Test
Plate size =30 cm x 30 cm Size of Pit = 1.5M x1.5MDepth of pit : 2.0