Close to two years have passed since disaster ravaged the Teesta river basin in the small Indian Himalayan state of Sikkim, bordering Tibet, including destruction of the dam of the Teesta Stage III project. The glacial lake outburst flood from the Lhonak Glacial Lake wreaked havoc on the Teesta basin in Sikkim and in West Bengal state downstream. The massive flood destroyed villages, towns, homes, and livelihoods and claimed over a hundred lives.
The Teesta Urja project got a fresh environmental clearance for the reconstruction. The proposal was approved by the Environment Ministry’s Expert Appraisal Committee on River Valley and Hydroelectric Projects on January 10, under the provisions of ‘expansion or modernization’ in existing projects.
The Ministry of Environment, Forest and Climate Change, which is responsible for oversight, maintained that no hearings were required because no new land acquisition was taking place for the project reconstruction. The appraisal committee sidestepped a new public hearing on the grounds that the reconstruction did not involve purchasing new land or displacing residents, and because a public hearing was conducted in August 2006.
The experts’ nod for the new dam comes against the backdrop of concerns the panel had itself raised over the structure’s safety and stability. The EAC also set conditions for the new dam including the setting up of early warning systems and the mapping of glacial lakes and landslide spots, while noting that the design aspects were yet to be approved by the government’s water authorities, Geological Survey of India and the Central Soil and Materials Research Station.
The $1.64 billion project, already subject to three cost overruns, has now restarted (as per statements from residents of Chungthang, unofficially. There is no confirmation, nor denial from the developer or the Sikkim government) with an additional infusion of $460 million. This excludes losses to life, property and public infrastructure damaged due to the dam burst, estimated to have cost an additional $1 billion. The $0.61 billion reconstruction is being financed by a consortium of Indian banks, public sector financial institutions and investment firms.
Teesta Stage III was initially budgeted at INR 5,705 crore rupees ($650 million). By the time operations began in 2017, costs had risen by nearly $1 billion, to INR 13,956 crore ($1.61 billion), most of which came from public sector banks and financial institutions funded by public money.
When existing hydro projects are expanded, the Central Electricity Regulatory Commission (CERC) determines tariff for the expanded capacity, based on the use of common infrastructure, de-capitalizing assets, including the value of de-capitalization.
The CERC regulations for hydropower projects, including those regarding partial generation, are primarily focused on ensuring efficient and reliable power supply, along with fair allocation of costs and benefits. “Design Energy” of the project is the key parameter used by the CERC for tariff determination, as outlined in the Techno-Economic Clearance (now called Concurrence) issued by the Central Electricity Authority (CEA) under Ministry of Power (MoP).
As the Sikkim government reconstructs the Teesta III 1200 MW hydropower dam, there are serious legal and technical implications which have not been factored in.
Critics contend there are some technical glitches in the dam design to the hurried clearance accorded.
Himanshu Thakkar of the South Asia Network on Dams, Rivers and People (SANDRP) questioned the rush to green light a project with a history of disaster, before new studies of the probable maximum flood risk in light of the disaster were completed. The Environment Ministry should have ordered a fresh environmental impact assessment, which is standard practice when the central electricity and water authorities are considering the dam reconstruction in a new way, he added.
Padamjit Singh, chief patron of the All India Power Engineers Federation (AIPEF), back in 2017 when the project was commissioned, argued that Teesta Urja was a failed public-private partnership project and was illegally operating by selling power at a rate much lower than the contracted rate and without having requisite power evacuation transmission lines in place.
“Calculating the probable maximum flood (PMF) is essential to determine a dam’s spillway capacity, which in turn affects dam safety. In the revised reconstruction plan, the PMF has stayed the same at 7,000 cumecs, which is a figure based on very old data from 2006,” explained Himanshu Thakkar.
But then why is the reconstruction plan not above scrutiny? Why does it raise serious technical and feasibility questions?
To begin with, once the project restarts operations, it has to apply for a fresh commercial operation date (COD) as per the CERC guidelines, and vetted by the grid operator, the Eastern Regional Load Dispatch Centre (ERLDC). This is the established norm as per the Ministry of Power.
In the words of Padamjit Singh, “As per CERC norms, Commercial Operation Date (COD) can be declared only after attaining 100% power (6 units at 200 MW) i.e. 1200 MW for 12 hours continuously. Part-load operation is not permissible for demonstration of COD. However, the proposed plan of reconstruction is in total abeyance of this condition or rule.”
The project consultant’s proposal is to rebuild the project in two stages.
In the first stage, it aims to achieve partial generation by constructing a suitable upstream cofferdam and using the existing water conductor system and powerhouse. The proposal for restoration of the project with partial generation through cofferdam will generate around 60% of designed energy.
Restoration of the main dam will take around 36 months after the start of partial generation. So around 48 months in total is the reconstruction time, according to the project developer. The proposal of the project consultant is not feasible because the de-silting chambers can be put into operation only after the concrete gravity dam is complete (i.e., after 36 months construction period).
“The proposal of the consultant tantamount to operating the powerhouse without de-silting chambers. In such projects which are liable to silt problems, like the Teesta Stage III, it will cause damage/erosion of turbine runner, leading to repeated breakdown of even interim power generation,” added Singh.
The Teesta-III project design provides for silt removal by posing the intake waters through two de-silting chambers, which have dimensions of 320m length, 13m breadth and 23m height, as per original project design documents (PDD). It must be stressed that as per original design, the de-silting chambers can be completed/constructed only when the dam itself is complete. Hence, while constructing the dam, the provision of de-silting chambers has to be ensured and included as a part and parcel of the dam itself.
“The proposal of the consultant is not feasible because the de-silting chambers can be put into operation only after the dam is complete (i.e., after 36 months), hence it is an impractical and illegal proposition,” Singh noted.
Also, the project consultant has not given any estimate of cost escalation and tariff resulting from capital cost increase in its reconstruction plan.
The assumption is based on restoration of the electro-mechanical equipment in 12 months, so there is a case for bringing the project back to full load operation at the earliest.
However, the consultant appears to have overlooked, and contradict themselves when they say that as per their own estimate, it would take 3 years to complete the construction of the concrete gravity dam (in addition to the 1 year for powerhouse equipment), thereby making the total repair period 48 months.
Even if the Stage 1 of the project (hydropower station) by building a cofferdam is completed, even then the station cannot be operated unless the de-silting channels are completed, as they are a part and parcel of the dam itself.
“Therefore, even if electrical and mechanical parts have been restored, nevertheless de-silting chambers cannot be ignored or bypassed, thus total time to complete repairs would necessarily include one plus 3 years and it is not feasible to run the project without first completing dam as well as de-silting chambers,” opined Padamjit Singh.
Another flaw in the plan is that the project consultant has estimated that within one year the powerhouse electrical and mechanical equipment can be restored i.e., ready for commissioning. This estimate is also not in order because the most critical and resisting equipment is the “stator winding” of each 200 MW generator, because the winding suffered flooding i.e., submergence, and it would be in all probability, beyond repair.
The alternative is to replace the defective winding with new winding. Winding replacement is a major repair work which is normally done at the OEM (Original Equipment Manufacturer) works, and not possible in situ.
It is high time that the Teesta Stage III project developers for once show some accountability and clarify the points raised by subject experts, without hurrying with the reconstruction and putting more public money into jeopardy. There should be transparency on all decisions taken and the rationale for taking them, in the public domain.
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