UNDERCONSTRUCTION GENERATION PROJECTS OF NEPAL ELECTRICITY ...
Transcript of UNDERCONSTRUCTION GENERATION PROJECTS OF NEPAL ELECTRICITY ...
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UNDERCONSTRUCTION GENERATION PROJECTS OF
NEPAL ELECTRICITY AUTHORITY
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GENERATION DEVELOPMENT IN NEPAL
Mini /micro hydro
Small hydro
Off Grid
Home solar
Biomass
bagasse
Captive diesel
In Grid
IPP
NEA NEA PPP
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NEA INVOLVED UNDER CONSTRUCTION PROJECTS CATEGORY PROJECT NAME CAPACITY TYPE EXPECTED
COMMISSIONING
NEA OWN Chameliya 30 MW PROR 2016/17 end
Kulekhani 3 14 MW Storage (cascade) 2016/17 end
Upper Trishuli 3A 60 MW ROR 2017/18
Rahughat 40 MW ROR 2019/20
NEA PPP (Subsidiary/ Associate companies)
Upper Tamakoshi 456 MW PROR 2018/19
Middle Bhotekosi 102 MW ROR 2018/19
Rsuwagadhi 111 MW ROR 2018/19
Upper Sanjen 14.8 MW ROR 2016/17 end
Sanjen 42 MW ROR 2017/18 end
Trisuli 3 B 37 MW ROR (cascade) 2018/19
Tanahu Hydro 140 MW Storage 2020/21
Total 1046.80 MW
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CHAMELIYA
• Completed above 95%.
• Faced various geological problems resulting in time and cost over run. • Hard rock in dam foundation not as expected.
• After excavation of complete 4.6 km tunnel, 843 m got squeezed.
• Mud flow from nearby rivulet Bhelgad entered the tunnel.
• Original location of Power house foundation was in alluvium so shifted back by huge back slope cutting and its stabilization.
• Cavities encountered on the sides of vertical shaft.
• Chameliya can be taken as unique example of geological problems.
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TUNNEL SQUEEZING MUD FLOW AFTER SQUEEZING
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TREATMENT OF SQUEEZED TUNNEL
PREPARING FOR TREATMENT BREAKING BY MACHINE BREAKING MANUALLY
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TREATMENT OF SQUEEZED TUNNEL
NEW STEEL RIB INSTALLATION
NEW STEEL BAR INSTALLATION
SHORTCRETING
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TREATMENT OF SQUEEZED TUNNEL
FINAL SECTION
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OTHER PROBLEMS IN TUNNELING Debris Flow Rock fall
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VERTICAL SHAFT
• Large cavity around shaft • Approx. 25 x 8 x 5 m
• Crushed material
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POWER HOUSE SHIFTING AND BACK SLOPE PROTECTION
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KULEKHANI 3
• Completed above 90%.
• This project also suffered time and cost over run owing to: • Collapse of Inclined Shaft
• Power house foundation
• Performance of E/M, H/M Contractor
• It is expected to be commissioned by the end of f/y 2016/17.
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UPPER TRISHULI 3A • Above 45% work is completed and would have been commissioned by now.
• Unfortunately, this project was hard hit by earth quake. As an impact of earth quake: • The access road to head works got completely damaged by making the head works
area inaccessible for about a year after EQ. Access road to surge tank also got damaged.
• A huge land slide got triggered up hill on the left bank of the river at head works causing a potential danger to stability of head works.
• Similarly a huge land slide triggered uphill near the tunnel inlet portal on the right bank near the head works causing threat to stability of inlet structures including the desanding basin.
• Most of the construction equipment and the construction material got damaged.
• Work is not resumed till date along with the contractual complications of EPC Contract in such events.
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RAHUGHAT • Civil contract terminated due to poor
performance of the contractor. • Now fresh invitation of bids published for
civil and hydro-mechanical as single EPC Contract.
• Due to financing from Indian Exim Bank, it will be limited bidding.
• Experience of previous contract used in new design. • Almost full tunnel is lined now. • Surge shaft is on surface now. • Capacity has been upgraded to 40 MW. • Transmission line is deleted.
• Total progress till the termination of civil contract was 13%
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LESSONS LEARNT • Geology, unlike Physics, is not exact Science.
• Since a 100% geological exploration during study is not possible, it is a Science of assumptions, probabilities and estimations.
• However, a credible and dependable study minimizes the geological surprises. It saves cost and time over run to a large extent.
• Even if it is early stage of the project, highest importance should be given to a detailed and credible study.
• Underground structures are safer in the event of an earthquake. Otherwise it is better to semi cover few of the structures.
• Even if it is same FIDIC Document, every contract is unique in nature and quite new contractual issues may be encountered.
THE STUDY
STRUCTURE
DOCUMENT
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