Question & Answer: 

1. What is the installed capacity of Tehri and Koteshwar Hydro Power Plants?

Installed capacity means the summation of the nameplate capacities of all the generating units of the generating station or the capacity of the generating station as reckoned at the generating terminals, as may be approved by Commission from time to time.
Installed capacity of Tehri HPP and Koteshwar HEP are as under:
Tehri HPP- 1000MW (4X250 MW)
Koteshwar HEP- 400MW (4X100 MW)

2. What are the Design Energy or Annual Design Generation Capacity of Tehri HPP and Koteshwar HEP?

Design Energy means the quantum of energy, which can be generated in a 90 % dependable year with 95 % installed capacity of the generating station.
Design Energy (Annual Design Generation Capacity) of Tehri HPP is 2797 MU and of Koteshwar HEP is 1155 MU. (Approved by CEA)

3. What is Plant Load Factor, Declared capacity, Infirm Power, Schedule Energy & UI charges?

  • Plant Load Factor is the ratio of the actual output of a power plant to its installed capacity less the auxiliary energy consumption over a period of time.
In relation to thermal generating station, it is termed as Plant Load Factor and for hydro generating station as Plant Availability Factor.
  • Declared capacity (DC)-Hydro Power Generating Station
  1. For run-of-river power station with pondage , storage-type power stations and Pumped Storage Plants declared capacity means the ex-bus capacity in MW expected to be available from the generating station over the peaking hrs during the  day, as declared by the generator, taking into account the availability of water, optimum use of water and availability of machines. The peaking hours for this purpose shall not be less than 3 hours within 24 hours period.
  1. In case of purely run-of-river power station, declared capacity means the ex-bus capacity in MW expected to be available from the generating station during the day, as declared by the generating station, taking into account the availability of water, optimum use of water and availability of machines;
  • Infirm Power means electricity injected into grid prior to the commercial operation of a unit or block of the generating station. It is also termed as unscheduled power.
  • Schedule Energy means the quantum of energy scheduled day ahead by the concerned Load despatch Central to be injected into the grid by a generating station for a given time period.
  • Unscheduled interchange (UI) Charges- All variations between actual net injection and scheduled net injection of Energy for the generating stations, and all variations between actual net drawal and schedule net drawal of energy for the beneficiaries shall be treated their respective Unscheduled Interchanges (UI), charges for which shall be governed by the relevant regulation specified by the Commission from time to time.
Now, unscheduled interchange is termed as Deviation Settlement Mechanism and UI charges as Deviation Settlement Mechanism charges.

4. What is the Auxiliary Consumption & Normative Auxiliary Consumption for Tehri ?

Auxiliary Energy Consumption or 'AUX' in relation to a period in case of a generating station means the quantum of energy consumed by auxiliary equipment of the generating station, such as the  quipment being used for the purpose of operating plant and machinery including switchyard of the generating station and the transformer losses within the generating station, expressed as a rcentage of the sum of gross energy generated at the generator terminals of all the units of the generating station.

Provided that auxiliary energy consumption shall not include energy consumed for supply of power to housing colony and other facilities at the generating station and the power consumed for construction works at the generating station.

Normative auxiliary energy consumption for-

1. Tehri HPP = 1.2 % (Underground Power House)
2. Koteshwar HEP = 1% (Surface Power House)

5. What is Plant Availability Factor and Normative Plant Availability Factor?

Plant Availability Factor: Plant Availability Factor of a generating station for month/ year means the average of the daily Declared Capacities (DCs) available for all the days of month / year expressed as a percentage of the installed capacity in MW reduced by the normative auxiliary consumption.
PAF= 10000 x∑ DCi/ {N x IC x (100 -AUX)} %
AUX = Normative auxiliary energy consumption in percentage
DC1 = Declared capacity (in ex-bus MW) for the ith day of the month which the station can deliver for at least three (3) hours, as certified by the nodal load dispatch centre after the day is over.
IC = Installed capacity (in MW) of the complete generating station
N = Number of days in the month / year
Normative Annual Plant Availability Factor (NAPAF): Normative Plant Availability Factor is basically PAF based on design energy considering all the constraints like maintenance of units, force outages & power potential at different reservoir levels etc.
Normative Annual Plant Availability Factor (NAPAF) for hydro generating stations shall be determined and approved by the Central Electricity Regulatory Commission (CERC).

6. What is the Normative Annual Plant Availability Factor of the Tehri HPP and Koteshwar Hydro Power Plant?

Normative Plant Availability Factor of Tehri HPP (1000MW) is 77% (approved by Hon’ble CERC).
Normative Plant Availability Factor of Koteshwar HEP (400MW) is 67% (approved by Hon’ble CERC.)

7. Is Tehri Hydro Power Plant running to its full capacity?

Tehri HPP is running at its full capacity since commissioning of all four Units in 2006-07. The energy generated from Tehri plant is 4060 MU, 3004 MU & 3101 MU for FY 2013-14, 2014-15 & 2015-16 respectively against design energy of 2797MU.

8. Is Tehri reservoir filling up to its Full reservoir level (FRL)? If not, what is the loss to the Nation & Government of Uttarakhand?

The Full Reservoir Level (FRL) of Tehri reservoir is EL830 M but presently permission granted by GOUK to fill the Tehri reservoir is up to EL 825 M. As a result, the full potential of the Project is not being utilized. If Tehri reservoir is allowed to fill up to FRL (EL 830) then there will be additional generation of 30 MU to 160 MU depending upon monsoon. The live storage capacity of Tehri reservoir between El 825 & EL830 is 195 MCM. If THDC fill reservoir up to EL 830, THDC can store more water during good monsoon. Further more water shall be made available for drinking & irrigation purpose from Tehri Dam during non-monsoon period between Oct - June.

9. Why the implementation of the Tehri Dam & HPP (1000 MW) has taken such a long period?

The main reasons for delay in implementation of Tehri HPP are:
  • THDC took over the project from Irrigation Department in 1989. Before that project was languishing due to shortage of funds in Irrigation Department apart from other reasons.
  • Opposition of Project by local people and Dharna by Sh. Sundar Lal Bahuguna on various occasions after THDC took over and decided to start main works of project like Dam, Spillway, Power House etc.
  • Govt. ban on shifting of population of old Tehri Town till decision on Rehabilitation in May’1996.
  • Review of technical aspects and other information relating to safety of Tehri Dam in June’1996.
  • Delay in Rehabilitation and Resettlement.
  • Formation of New State (Uttarakhand).
  • Review of Environmental and Rehabilitation aspects of Tehri Dam by Prof. Hanumantha Rao Committee during 1996-97.
  • Review of seismic safety of Tehri Dam by the Committee headed by Dr. Murli Manohar Joshi constituted in April’2001 in light of:
-Bhuj Earthquake.
-Impact of Tehri Dam on self purification quality of Gangajal etc.
  • Geological Surprises faced in zone of water intake.
  • Delay in achieving required MDDL due to stay by Hon’ble High Court in Aug’05 on PIL against closure of T2 Tunnel.

10. What are the benefits to Uttarakhand State from THDCIL?

THDCIL has made maximum investment in Uttarakhand. Cumulative investment of about ` 120 billion has been done by THDCIL in the Uttarakhand State till date. Further investment of approx ` 60 billion is proposed in the near future in the upcoming new Projects.
THDCIL is also contributing to State Treasury through Taxes. In addition, expenditure of ` 15 Billion incurred on Rehabilitation of Tehri Project Affected Families and infrastructure facilities created in Rehabilitation sites has pump primed the local economy.
The Home State Uttarakhand is directly benefitted by the supply of 12% of free power generated from THDCIL’s generating stations.
The New Tehri Town has been developed as a modern hill station with all the modern facilities for education (including an ITI and a University), Hospital, Financial Institutions, District Administration Offices, Markets, Bus Stand, and places of worship etc. This has led to enhancement of employment opportunities in commercial ventures like boating, transport, vehicle repair shops, business, hotel industries etc.
THDCIL has given direct employment to youth of Uttarakhand. The employment given by THDCIL is about 61 % (492 out of 801) from the Tehri District and about 125 persons from other Districts of Garhwal Region. Besisies this,the youth of Uttarakhand were provided necessary help and guidance for engagement in suitable self employment opportunities.
THDCIL have also concerns regarding education in the state. THDCIL have opened Engineering College cum Hydro Power Institute named s THDC Institute of Hydro Power Engineering and Technology in the State. THDCIL have also adopted two ITIs (ITI Chamba and ITI Gopeshwar). Besides this, THDCIL is also running schools in the vicinity of Project areas in Uttarakhand.

11. Why traffic is not being allowed over the Tehri dam top?

Tehri dam is constructed with earth and rockfill. There is a tunnel 5 mt. below the dam top. It is apprehanded that vibrations/micro trimmers triggered by movement of vehicles could affect structural safety. Due to movement of public vehicles there is danger of occurrence of subsidence in its various parts and regions. To study the Dam behaviour, various types of sensitive instruments have been installed in it, on which adverse impact may occur due to heavy Vehicular traffic.
The vehicular traffic is also not being allowed due to safety reasons. Superintendent of Police of Tehri during July’ 2012 had also communicated that vehicular traffic may not be allowed over the Dam top in order to strengthen the Dam safety in view of terrorist activities.
Ministry of Power, Govt. of India vide memorandum dated 21st June 2006, constituted 2 Expert Committees (related to Technical and safety aspects) for allowing movement over dam top. Ministry of Power, Govt. of India directed for compliance of suggestions given by expert committee & not to allow movement of commercial and personal vehicles over Tehri dam. Although, it was mentioned that villagers of nearby villages may be permitted for pedestrian movement over dam top after issuing passes by District Administration/ Security Agency (CISF).

12. What is the risk of flooding in Rishikesh and Haridwar when water from the Tehri Reservoir is released? Or During rainy season, how Tehri Dam is helping the flood moderation?

Flood moderation and regulation is one of the major benefits of Tehri Dam. During heavy rains Tehri Dam actually help people of Gangetic Plains viz Rishikesh, Haridwar and other down stream cities from the fury of floods by absorbing the flood in its huge reservoir. With regulated flow from Tehri Project, it is ensured by the project authorities that the people in the down stream areas are saved from the heavy water flows in river Ganga as in the years 2010 & 2013.
Tehri Dam is a 260.5 m high Earth & Rock fill Dam. The dam has gross storage capacity of 3540 Million Cubic Meter (MCM) & live storage capacity of 2615 MCM between Minimum Draw Down Level (MDDL) (El 740m) and Full Reservoir Level (FRL) (EL 830m). The incoming flood water can be stored in the Reservoir during monsoon upto FRL. But, once the reservoir level reaches FRL, Spillways come into operation for releasing flood water. Tehri Spillways have been designed for a peak maximum flood (PMF) of 15,540 cumecs, which has a probability of occurring in 1:10,000 years.     
Tehri spillway comprises Chute spillways on Right Bank, 2 Nos. Right Bank shaft spillways (RBSS) and 2 Nos. Left Bank shaft spillways (LBSS). The sequence of operation of spillways are as under :-
  1. As soon as the water level rises above 830.0 m. the Chute Spillway would be brought into operation by stage-lifting all the three gates simultaneously.
  2. If the water level continue to rise above 830.0m at full gate openings of the Chute Spillway, the LBSS would be brought into operation by stage lifting of both the gates. The lifting of gates is similar to that of Chute Spillway gates.
  3. If at fully open gates of Chute Spillway and LBSS, the water level continues to rise above 830.0m the un-gated RBSS, with intake at 830.20 m. shall come into operation and discharge the excess flow.
  4. In the event of PMF of 15,540 cumces, 13043 cumces will be released through spillways as above and remaining water will be stored in the reservoir between FRL(830m) & MWL (835m)   
Above mentioned sequence of spillways operation is based on conceptual approach of reservoir operation but in practice it is governed by reservoir rule curve and spillways can be operated even before achieving the FRL if the situation arises due to higher inflows.

13. Tehri Dam has created Tehri Reservoir where the free flowing river Bhagirathi and Bhilangna have become stagnant. Does it not affect the quality of water?

Though the water in the reservoir appears stagnant but actually it is not. In order to assess the impact of Tehri Dam on the water quality of river Bhagirathi, water quality modelling study was also got carried out by the University of Roorkee. The study had concluded that there would be no adverse effect on the water quality due to impoundment. Dissolved Oxygen (DO) and Bio- Chemical Oxygen Demand (BOD) in the reservoir are expected to remain within permissible limits desired for drinking water source. 
Central Water & Power Research Station (CWPRS), Pune, also carried out mathematical model study on water circulation and concluded that water in reservoir remains under dynamic circulation throughout the year and does not remain stagnant. Hence though the water in reservoir may look static from outside, actually it is under dynamic circulation within the reservoir.
Regarding  the issue of self  purification quality  of Ganga (Bhagirathi) water, a study was carried out by National Environmental Engineering Research Institute, Nagpur (NEERI) titled “SELF PURIFICATION QUALITY OF BHAGIRATHI/GANGA: IMPACT OF TEHRI DAM(2004)”. This study reveals that the uniqueness of river Bhagirathi / Ganga lies in the sediment content which is more radioactive compared to other river and lake water sediments and can release Cu and Cr which have bactericidal property and can harbour and cause proliferation  (under static condition) of that reduce and ultimately eliminate coliforms from the overlying water column. Thus Tehri Dam is not likely to affect the quality or self preservation property of river Bhagirathi /Ganga, as it mimics a static container which is conducive for conditions responsible to maintain the water quality.
Thus it can be seen that enough precaution stands taken by project authorities in dealing with the concern and faith of people on water quality after reservoir is formed. In all studies it has been concluded that water quality remained same as it was before formation of reservoir due to construction of Tehri Dam.

14. What benefits are given to the wards of Project Affected Families for admission in the THDC Institute of Hydro Power Engineering and Technology?

5% seats are reserved in THDC Institute of Hydro Power Engineering and Technology for wards of Project Affected Families of Tehri Project.

15. Tehri Dam has helped in irrigation in the command area in Uttar Pradesh and providing drinking water to various town of Uttar Pradesh and also to Delhi. What are the benefits of the project to other states, where Ganga is flowing after U.P.

Tehri Hydro  Power Complex (2400 MW) a multipurpose project, was conceived & designed to store surplus water of the river Bhagirathi during monsoon and releasing stored water after monsoon as per the requirement of irrigation for UP and drinking purposes for UP & Delhi besides giving peaking support to grid.
The electricity produced by Tehri Dam and HPP is provided to nine beneficiary states of Northern Region viz. Uttarakhand, Uttar Pradesh, Haryana, Himachal Pradesh, Delhi, Punjab, Jammu and Kashmir, Chandigarh and Rajasthan.
The water is stored in reservoir of Tehri Dam during Monsoon Season and is released round the year as per the drinking & irrigation requirement  which makes availability of water in Ganga throughout the year which may be utilised by other states for drinking, Irrigation and Commercial Purposes like Power Generation etc. where Ganga is flowing. Also water availability is maintained round the clock at Haridwar/Rishikesh/Allahabad during important Snan. The main benefits due to availability of additional water from Tehri dam are:
  • Irrigation Command Area -  Additional        2.70 Lac Ha
                                            -Stabilization      6.04 Lac Ha
  • Drinking Water for Delhi   (162 MGD) -     300 Cusecs (for 40 lacs population)
  • Drinking Water for UP (108 MGD)       -    200 Cusecs(for 30 lacs population)
  • Annual Increase in generation of D/S projects -     200 MUs

16. Is it a fact that availability of water in Ganga is higher for Snans (Magh Mela ,Kumbh mela etc) after the creation of Tehri Dam as compared to snans before construction?

Yes, this is a fact. During Melas every year the discharges form Tehri Dam augmented to facilitate Snans / rituals at Haridwar and places as far away as Allahabad and Varanasi. For example, availability of water was ensured by THDCIL for smooth snans during Maha Kumbh held at Haridwar in 2010 and Allahabad in 2013. Tehri Dam released 250 -300 cumecs water from Tehri reservoir in order to ensure adequate water in Ganges for Kumbh mela snans when the water inflows in the Tehri reservoir were around 50-70 cumecs. This was also appreciated by State Govt., Mela Authority & Sant Samaj.

17. How Tehri Dam has contributed to the economy in National and regional (Uttarakhand) level?

Tehri Dam has been contributing in its own way, towards the growth of the economy in National and Regional (Uttarakhand) Level.
One percent increase in production of electricity in the nation contributes to 1% increase in GDP.
The electricity produced by Tehri HPP & Koteshwar HEP is provided to nine beneficiaries of Northern Region viz. Uttarakhand, Uttar Pradesh, Haryana, Himachal Pradesh, Delhi, Punjab, Jammu and Kashmir, Chandigarh and Rajasthan.
THDCIL is earning profit since first year of commercial operation of Tehri HPP i.e. 2006-07. A part of the profits earned by THDCIL is paid back as dividend to shareholders– Govt of India and Govt of UP.
A part of the profit earned by THDCIL (2% of PAT) is earmarked for CSR and Sustainability activities in non lapsable CSR and Sustainability fund. 
12% of Power generated from Tehri HPP (1000 MW) and Koteshwar HEP (400 MW) is provided Free of cost to the Home State of Uttarakhand.
The company pays taxes on purchase of goods and services, creates direct and indirect employment and stimulates the local economy.
Tehri Project will also play an important role for the development of surrounding areas & in improving the quality of life by providing employment opportunities and additional source of revenue in the form of fishing, tourism, water sports etc for which GoUK is taking initiatives.

18. What types of environmental mitigation measures have been taken during construction of the Tehri Hydro Power Project?

Measures taken to mitigate adverse impact on environment during construction of the Tehri Hydro Power Project are briefed below-
  1. Catchment Area Treatment (CAT): Catchment Area Treatment (CAT) has been completed implementing the Action Plan by the Forest Deptt. of Govt. of Uttarakhand (earlier Government of U.P.) with funds provided by THDC as per requirement. The area of 52,204 ha. including 44157 ha. of forest land and 8047 ha. of agricultural land has been treated by forest department.
  2. Preservation of Flora and Fauna: The studies were conducted through Botanical Survey of India (BSI) for flora and Zoological Survey of India (ZSI) for fauna affected due to reservoir. The reports were submitted to MOEF in 1993. For preservation of flora, a Botanical Garden located adjacent to the Reservoir with plantation of special species coming under submergence has been established in an area of 14.28 Ha.  The Botanical Garden has been established to preserve important flora of the region. For this purpose a high-tech nursery having plants of the submerged area is in operation. Botanical garden is being maintained by Sate Forest deptt. through funding by THDCIL. As suggested by ZSI, a Mahseer Fish hatchery & fish farm site for induced artificial breeding of mahseer fish has been developed near Koteshwar Dam.
  3. Water Quality Monitoring: In addition to the water quality studies done by IIT, Roorkee and NEERI, the water quality testing is being carried out regularly through CPRI, BHEL, Haridwar at the sampling locations Dharasu (river Bhagirathi), Ghansali (river Bhilangna), Zero point (D/s of Tehri Dam), Devprayag U/s and Devprayag D/s. No adverse effect on the water quality has been observed after impoundment of reservoir.
  4. Disaster Management Plan (DMP): The Disaster Management Plan (DMP) prepared by THDC, was submitted to the Ministry of Agriculture (MoA), the Nodal Ministry for this purpose, in April 1992. After deliberations, the Ministry of Agriculture (MoA) had, on 24.2.99, conveyed approval to the DMP.   
    This Disaster Management Plan is regularly up-dated  every year before monsoon and reviewed in coordination with Disaster Mitigation & Management Centre (DMMC), Govt. of Uttarakhand, Dehradun, which is the nodal agency for dealing disasters in the state of Uttarakhand.
  5. Compensatory Afforestation: The Catchment Area Treatment (CAT) Plan for Tehri Hydro Power Complex requiring compensatory afforestation has been completed on 4586 ha. area of non-forest land (Lalitpur - 3960 ha & Jhansi - 626 ha.). This includes compensatory af forestation against forest land of 338.932 ha. affected due to Koteshwar HEP (400 MW). The plantation done on the non-forest land is being converted into protected forest by the State Forest Department. The compensatory afforestation against 1358.20 ha. area of forest land acquired (at Virbhadra, Dehradun and Pathri in Haridwar) for rehabilitation of Tehri Dam PAFs has been done on an area of 2716.40 ha. of degraded forest land in Khanpur Forest Range in District Haridwar at the project cost.
  6. Command Area Development Plan (CADP): The Command Area Development Plan (CADP) was submitted by the GoUP and was forwarded by Ministry of Power to MoEF in July 1998. CAD Plan also included areas which now form part of Uttarakhand.

19. Has any study been conducted to evaluate the conditions/ status of project affected families of Tehri Dam project? If yes, the details thereof.

To examine the effectiveness of R&R, a Socio Economic Study of the families rehabilitated was conducted by the Administrative Staff College of India in March, 1993, which broadly concluded that after rehabilitation, the oustees have been provided with better facilities and amenities than they had at their earlier habitats. The value of assets and income generation from agriculture of oustees has considerably increased. Their access to markets and wage earning opportunities also improved substantially. The annual income of households after rehabilitation has risen considerably. The new settlements are provided with pucca buildings, electricity, drinking water facilities, good medical facilities, LPG connections etc.
The study was updated by ASCI, when the R&R process was substantially completed, to compare the results of the first study and to understand any changes. In its report of May, 2009, ASCI has concluded that in the R&R for Tehri HEP, which was carried out on a massive scale, there is improvement in living standards of PAF’s when compared with the areas where they stayed earlier.

20. What is the status of Rehabilitation of Tehri Project?

The Rehabilitation of Tehri project was implemented by the State Government of Uttarakhand with funds provided by THDCIL. The rehabilitation has been completed. Total 5291 Urban families and 5429 Rural Families were rehabilitated whereas 3810 partially affected families need not to be relocated.
In view of the representation received from the local inhabitants, the Director (Rehab), GoUK decided to get the re-survey done by the Survey of India so that the actual line could be drawn at RL-835 mtrs.  On the advice of Director (Rehab), the Survey of India conducted the survey and fixed a new demarcation line of RL-835mtrs. Due to error in demarcation of survey line at RL 835m, some more land was to be acquired in 45 villages (already included in 109 villages) and additional 108 eligible families were rehabilitated as per the demarcation of new survey line of RL 835 m.
The rehabilitation of all identified families upto EL 835 m was completed as per the R&R policy. For rehabilitation of additional 108 families due to fresh survey of Full Reservoir line, the State Govt. has confirmed that land upto RL 835M had already been acquired and all affected families which were found eligible, have been rehabilitated. Cost of Rehabilitation and Resettlement was Rs.1380.96 Cr. As decided in Meeting held between Government of India, Government of Uttarakhand and THDCIL under Chairmanship of Secretary (Power), Govt. of India on 30.06.2011, THDCIL released Rs.102.99 Cr against full and final settlement for completion of R&R works of Tehri Project.
The total cost of R&R  as of now is Rs.1484 Cr.

21. Are people affected by Tehri Project still having some grievances and what is the mechanism to settle the grievances?

There are some grievances from Project Affected Families. In order to listen and examine the grievances from Project Affected Families a Grievance Redressal Cell is in place. In compliance of the orders of the Hon’ble Supreme Court, the Registrar General, Uttarakhnad High Court appointed a Retired District Judge (Additional) to look into the grievances of the PAFs relating to compensations, allotment etc.

22. Is CSR and Rehabilitation & Resettlement same?

No, CSR and Rehabilitation and Resettlement (R&R) are not the same. R&R is applicable to project affected families who have to be compensated for the impact of the project on their land/property/livelihood. They are listed at the project preparation stage and are covered for R&R at project cost.
CSR is Corporate Social Responsibility under which the business focuses on triple bottom line concept i.e. people, planet and profit. The expenditure under CSR is incurred out of the profits of the business.
As per the current Government Guidelines, every company having net worth of rupees five hundred crore or more, or turnover of rupees one thousand crore or more, or net profit of rupees five crore or more during any financial year is mandated to take up CSR activities as per the provisions of Companies Act, 2013 and the CSR rules. It is to be ensured that the Company spends, in every financial year, at least 2% of the average net profits of the Company made during the three immediately preceding financial years.
THDCIL has been actively involved in CSR activities in the areas of education, health, skill development, integrated rural development & income generation, infrastructure support and environment protection. Details of expenditures incurred by THDCIL since FY 2010-11 are as below:
Sl. No. Financial Year Budget of CSR as per guidelines (Rs. in Cr.) Actual expenditure made (Rs. in Cr.)
1 2010-11 9.81 9.77
2 2011-12 13.58 15.04
3 2012-13 16.04 19.84
4 2013-14 10.63 15.79
5 2014-15 13.77 29.09
6 2015-16 13.34 13.35

For more details on CSR please refer the link CSR on THDCIL’s website “thdc.co.in”.