According to a Pakistani newspaper, though the most recent flooding is different in nature compared to the one in 2010 — the latter was a flash flood while the current is a riverine flood — in both cases, it can be argued that the damage caused by both disasters is the outcome of lessons not learnt in demography as well as unwillingness to carry out flood protection measures across Pakistan. A research carried out by this author in 2017, about 2010 floods in Pakistan, history has repeated itself because no corrective measures were taken. It was almost déjà vu in 2022 — and yet, no lessons had been learnt. After all, disaster management is more about preparedness than response.

In a case of The pot calling the kettle black, the planning minister Ahsan Iqbal is reported to have said Pakistan was feeling the effects of climate change caused by richer nations and their “irresponsible development”. While all natural disasters can be ascribed to climate change a study of the earlier research will reveal that the Pakistan government did precious little to prevent recurrence of events that could have reduced the impact of the calamity. For example almost all barrages in the country are silted up to the brim, where is the scope to cushion the floods. The government should be questioned and asked to give an account of desilting measures taken since 2010.

THE FACTS AS THEY STOOD IN 2010

The floods in Pakistan now show signs of abating but the havoc caused by them will continue to mount.  It is too early to measure even the immediate losses of lives or property, both private and public, although over 2000 persons are estimated to have died and 21 million become refugees in their own country.  Secondary damages to agricultural land and animal husbandry will take years to recoup.  At one point about one-fifth of Pakistan’s total land area had goneunder water.  Floodwaters have destroyed crops :  an estimated 700,000 acres of cotton, 200,000 acres each of rice and sugar cane and 300,000 acres of wheat.  This will impact the agricultural economy which contributed 20.4% of Pakistan’s GDP last year.  The cascading effect into industry and trade is bound to add to economic woes.

Scientists have described this catastrophe as a once-in-a-century flood. Out of a Population of 168 million nearly 21 milion people have been affected by floods out of a total area of Pakistan of 796 095 square kilometers, the Flood-affected area is 160 000 square kilometers. In a country where already a large percentage of the population is living as refugees, an additional 1.85 million homes have been destroyed or damaged due to floods. Look at the fact sheet of the present disaster:

Pakistan Flood Losses (as on 6 September 2010) Source:  NDMA, PDMA
Province	Deaths	Injured	Houses Damaged	Population Affected
Balochistan	48	102	75,261	*672,171
Khyber Pakhtunkhwa	1,154	1,193	200,799	4,365,909
Punjab	110	350	500,000	8,200,000
Sindh	186	909	1,058,862	6,988,491
AJK	71	87	7,108	245,000
Gilgit Baltistan	183	60	2,830	81,605
Total	1,752	2,701	1,844,860	20,553,176
* Additional 600,000 IDPs from Sindh are living in Balochistan

The degree of severity to which people have been affected by the floods varies depending on their particular losses and damages. UN assessments have been launched in at least three provinces to identify severely affected families who require life-saving humanitarian assistance. The UN experts have identified 2.7 million people in Khyber Pakhtunkhwa, 5.3 million in Punjab and 4.4 million in Sindh that are in need of immediate humanitarian assistance.

Approximately 4 out of 5 people in the flood-affected areas depend on agriculture for their livelihood. Across the country, millions of people have lost their entire means to sustain themselves in the immediate and longer term, owing to the destruction/damage of standing crops and means of agricultural production.  One of the greatest challenges on the ground is helping farmers to recover their land in time for wheat planting beginning in September/October and to prevent further livestock losses. According to the FAO figures released on 3^rd September 2010, the scale of losses to the agriculture sector caused by the Pakistan floods is unprecedented and further unfolding:

•  The Agriculture Cluster rapid damage assessments, completed in half of all flood-affected districts, found that 1.3 million hectares of standing crops have been damaged
•  Countrywide damage to millions of hectares of cultivatable land, including standing crops (e.g. rice,maize, cotton, sugar cane, orchards and vegetables) appears likely
•  Loss of 0.5-0.6 million tonnes of wheat stock needed for the wheat planting season
•  Death of 1.2 million large and small animals, and 6 million poultry (Department of Livestock)

While the full extent of the damage still cannot be quantified and assessments are ongoing, the direct and future losses are likely to affect millions of people at household level, as well as impact national productive capacity for staple crops, such as wheat and rice. The FAO feels that response to needs in the agriculture sector cannot be underestimated nor delayed.

The political spillover is equally if not more worrisome.  Relief efforts have highlighted the inefficiencies and corruption endemic in the Pakistani administrative set-up, magnified as it is becoming in the eyes of the already disenchanted masses, especially the internally displaced. The fear is that    fundamentalist organizations will extend their grip over affected populations by filling in wide gaps in disaster relief left by Pakistan Government and international relief agencies.  All this adds fuel to the already political fire in a volatile and unpredictable Pakistan.

Even if Pakistan wades through the floods, what is there to prevent another water disaster in the future?  To answer this question, one must examine these floods in a broader framework.  Pakistani meteorological data points to unusually heavy rains in July – August in the Khyber Pakhtunkhwa and Punjab provinces as the main cause of the floods.  Satellite pictures corroborate this.

Satellite Map shows the swelling Indus River at Sukkur Barrge Source NASA

 

According to a  WAPDA (Water and Power Development Authority) ] press release on Water Situation on 03 – 09 – 2010 the 24 hour Inflows / Outflows (in Cusecs) of the major Dams on the rivers in Pakistan were as follows:

Indus at Tarbela 203300 / 203300 Cusecs

Kabul at Nowshera 42000 / 42000 Cusecs

Indus at Chashma 249100 / 244100 Cusecs

Jhelum at Mangla 42800 / 42800 Cusecs

Chenab at Marala 87000 / 67400 Cusecs.

The above figures indicate that the Pakistani dams/barrages are virtually unable to retain any water, as can be seen above, almost all of the inflows are equal to the outflows. This is normally the case in monsoons for some dams but the figures are shocking because not a single dam except for Marala on the Chenab has been able to absorb some 20,000 cusecs of water.

Balochistan Times (August 21, 2009) reported that since the Chashma Barrage had been filled with water along with Tarbela Dam and Mangla Dam as a result of filling of these water reservoirs, IRSA had directed the provinces to use the released water as much as they needed without any restrictions. According to IRSA (Indus River System Authority)  officials, besides Mangla and Tarbela Dams the approximate inflow of water in the other rivers was 319500 cusecs and 4000 cusecs from river Kabul, all of which was being released as Tarbela and Mangla had filled completely. The CJ canal had been closed so that the Chashma Barrage could be destilled. The plus side for power starved Pakistan was that with the filling of dams with water, the power production had been increased, from which about 4000MW power was being generated from hydel power, which  reduced load shedding in the country..

The flood affected areas were mostly along the main Indus River and its western tributaries – Swat and Kabul; and less so from the eastern tributaries – Jhelum, Chenab and Sutlej.  This should not however obscure the overall picture.  More than 80% of the total water flows in the Indus river- system is accounted for by snowmelt and rainfall in the mountainous regions which are largely beyond its political control and belong to Afghanistan, India and China.  According to one estimate, the Kabul river accounts for 20 to 30 MAF of total annual flows, the main Indus 100 MAF and the Jhelum and Chenab 60, while the Ravi, Beas, and Sutlej add another 40 MAF or so. Floods are a cumulative effect of all these flows.

Initially, storage dams like Mangla and Tarbela   were built to modulate irrigation and control floods. But some 7 MAF of their storage capacity has already been silted up. And Pakistan has been singularly unsuccessful in building additional storage capacity to compensate, let alone provide for enhanced irrigation and flood control needs.  A major project – the Kalabagh dam – has failed to get off the drawing boards for two decades because of internal bickering between its provinces.  The international segmentation of the Indus basin rivers complicates the problem still further, particularly in relation to the two principal upper riparians – India andAfghanistan – with which Pakistan has troubled relationships.

The 3,200 km long Indus, one of the mighty rivers of the Indian subcontinent,   flows down from the Himalayas of Tibet, towards north-west through India before turning sharply southwards through  Pakistan,  draining into the Arabian Sea. Some of its water comes from melting Himalayan glaciers, but the vast majority is contributed by the monsoon. The monsoon floods are triggered almost annually. Historical records indicate that during a warm period ending about 6,000 years ago, the Indus was a monster river, more powerful and more prone to flooding than today.  Then, 4,000 years ago, as the climate cooled, a large part of it simply dried up. Deserts appeared whether mighty torrents once flowed. The matter of public debate is whether, with global warming, will the river again turn monstrous. A matter which further compounds the problem is the fact that siltation reduces the rivers capacity to hold water. Even with the total quantum of precipitation being the same, the intensity of rainfall gets aggravated by global warming resulting in unmanageable discharges.  Pakistan, which spends more of its scarce financial resources in building defences against India, has been unable to enhance its Hydraulic infrastructure comprising  of dams and barrages. In fact, due to siltation its overall storage capacity has further reduced.

Pakistan is, thus at a fork in the road.  It can either continue confrontationist policies which underlie present arrangements (or lack thereof) and face similar or perhaps bigger flood disasters in future, if anticipated climate change effects do materialise. Or it can chose to cooperate with countries in the Indus basin with a view to building an integrated system of storage dams, flood control installations and power generation stations which will help to modulate flows and avert floods, thereby benefitting Pakistan’s agriculture particularly its struggling farmers. The attendant hydropower potential is also huge and can be tapped for the energy-hungry Pakistani economy, as well as cross-border sales to India.  The big question is whether the Pakistan’s rulers can change their confrontationist mindset to make this possible.  If there was no deficit of trust India could have stored water even in the eastern rivers of the Indus basin to be used as a kind of buffer during floods. But, for that an integrated basin management is required, because the mighty rivers, follow their own course, they do not recognize man made political boundaries.

A  preliminary report was published in Hindu Business Line on 19th October 2010. Business Line version was available on the net at the following URL:

http://www.thehindubusinessline.com/2010/10/19/stories/2010101950330900.htm

Since it is a very old link it is probably no longer available but can be read on the link below

Pakistan floods reveal deep-rooted problems

 

Acronyms

NDMA National Disaster Management Authority

WAPDA Water and Power Development Authority

IRSA Indus River System Authority

OCHA United Nations Office for the Coordination of Humanitarian Affairs

FAO Food and Agriculture Organisation

IDP Internally Displaced Person

MAF Million Acre Feet

Cusec Cubic Feet per Second

Everyone is talking about oxygen concentrators now. Most of us had not heard of them before. Many know about distillers which extract water from air, yet very few realised that even oxygen can be extracted from air. So what is an Oxygen Concentrator and how do you choose the right one?

The most important is to understand that Covid patients require 90% Oxygen concentration at 1to 5Litre flow and above to 10L

Tips on Selecting the right oxygen concentrator.

The most important is to understand Covid patients require 90% Oxygen concentration at 1to 5Litre flow and above to 10L when they are suffering with acute respiratory discomfort.

90% oxygen concentration is the most important point here.

1. We can break down oxygen concentrator into small (5 to 10 kg) oxygen concentrator suitable for COPD patients, medium (15 to 19kg) and large (20kg and above) oxygen concentrators are suitable for critical care and for COVID patients.
2. Small oxygen concentrators can have options from 1 Litre to 9 Litre Flow but this does not mean you get 90% oxygen at higher flow like at 5 litre. On small oxygen concentrators 90% oxygen contration is achieved only at lower flows of 1litre to 2 litre. on higher flows the oxygen concentration drops to 30% as you increase the flow. Suitable for COPD patients but not for COVID patients.
3. Check the specs of the oxygen concentrator and if you see 90% – 30% or ( 1L/min , 2L/min) means 90% oxygen is available only at 1Litre flow or 2Litre flow respectively and on higher flows oxygen drops to 30%. The air we breathing is with 29% oxygen. So small (5kg to 10kg ) oxygen concentrator at higher flows gives output of 30% oxygen means its just blowing air.
4. weight is the best indicator to understand the oxygen production capacity.

A 5kg to 10kg oxygen concentrator means a small compressor which will only mange to give an output of 90% oxygen at 1 litre to max 2 Litre

A 15kg to 19kg Oxygen Concentrator will have a compressor that can easily give an output of 90% oxygen at flows from 1 Litre to 5 Litre Oxygen (Ideal for COVID patients and critical care patients)

A 20 kg and above oxygen concentrator will have a large compressor which can give an output of 90% oxygen from 1Litre to 10Litre flow. (Ideal for COVID patients and critical care patients and for dual patients to use same machine with accessories)

Please do not only see the output flow of an oxygen concentrator like 5litre, 10litre or so. the most important is to make sure you get 90% Oxygen at highest flow level.

For a small family with no senior citizens a 5 litre at 90% oxygen concentration should be good enough.

For 2 senior citizens or for a big family 10 litre at 90% oxygen concentration should be good enough as it can support 2 patients at once if the need arises. And can assist senior citizens during home critical care if the need arises.

Please do not get fooled and pay big money for small oxygen concentrator sold by highlighting 5 Litre and 8 Litre and do not give an output of 90% concentration of oxygen at higher flows which is the need of the hour.

Please read the specs well and if required please ask your supplier to show you the oxygen output on an oxygen analyzer at higher flow of 5 Litre or 10 Litre.

they are suffering with acute respiratory discomfort.

90% oxygen concentration is the most important point here.

1. We can break down oxygen concentrator into small (5 to 10 kg) oxygen concentrator suitable for COPD patients, medium (15 to 19kg) and large (20kg and above) oxygen concentrators are suitable for critical care and for COVID patients.
2. Small oxygen concentrators can have options from 1 Litre to 9 Litre Flow but this does not mean you get 90% oxygen at higher flow like at 5 litre. On small oxygen concentrators 90% oxygen contration is achieved only at lower flows of 1litre to 2 litre. on higher flows the oxygen concentration drops to 30% as you increase the flow. Suitable for COPD patients but not for COVID patients.
3. Check the specs of the oxygen concentrator and if you see 90% – 30% or ( 1L/min , 2L/min) means 90% oxygen is available only at 1Litre flow or 2Litre flow respectively and on higher flows oxygen drops to 30%. The air we breathing is with 29% oxygen. So small (5kg to 10kg ) oxygen concentrator at higher flows gives output of 30% oxygen means its just blowing air.
4. weight is the best indicator to understand the oxygen production capacity.

A 5kg to 10kg oxygen concentrator means a small compressor which will only manage to give an output of 90% oxygen at 1 litre to max 2 Litre

A 15kg to 19kg Oxygen Concentrator will have a compressor that can easily give an output of 90% oxygen at flows from 1 Litre to 5 Litre Oxygen (Ideal for COVID patients and critical care patients)

A 20 kg and above oxygen concentrator will have a large compressor which can give an output of 90% oxygen from 1Litre to 10Litre flow. (Ideal for COVID patients and critical care patients and for dual patients to use same machine with accessories)

Please do not only see the output flow of an oxygen concentrator like 5litre, 10litre or so. the most important is to make sure you get 90% Oxygen at highest flow level.

For a small family with no senior citizens a 5 litre at 90% oxygen concentration should be good enough.

For 2 senior citizens or for a big family 10 litre at 90% oxygen concentration should be good enough as it can support 2 patients at once if the need arises. And can assist senior citizens during home critical care if the need arises.

Please do not get fooled and pay big money for small oxygen concentrators sold by highlighting 5 Litre and 8 Litre and do not give an output of 90% concentration of oxygen at higher flows which is the need of the hour.

Please read the specs well and if required please ask your supplier to show you the oxygen output on an oxygen analyzer at higher flow of 5 Litre or 10 Litre.

Also most importantly consult a doctor before you invest your hard earned money in the device. Right now, because of a shortage of oxygen supplies, the concentrators are overpriced. As soon as supply meets demand, the price of concentrators will come down.

Life “is a tale told by an idiot, full of sound and fury, signifying nothing.” So said Shakespeare in Macbeth, a tragedy of epic proportion where the eponymous hero fell because of only one tragic flaw: “Vaulting ambition, which overleaps itself.”  Covid19 brought the “sound and fury, signifying nothing” part of Macbeth like a thunderbolt rolled onto an unsuspecting mankind. And Hamartia, or the tragic flaw, that Shakespeare’s tragic heroes had, has its echo in present times too. Covid19 lays bare our fault lines and exposes our flaws like never before. It has, in fact, come as a great teacher to mankind – perhaps because the ‘kind’ in “man” had shrunk to a miniscule level. It has given us a huge nudge to readjust our priorities that were slinking to abominable levels of putrid materialism.  Hmm…..looked closely, it also has been a period of wish-fulfillment, the collective wishes of entire mankind, or rather man-unkind, witnessing fruition of shared desires in a way unparalleled.

To further explain my points, let me take the first premise of collective wish fulfillment. Was the entire human race not clamoring for clearer skies, cleaner air and sparkling water? Millions of dollars were being spent on hosting international meets that often ended up revealing more dissensions than agreements. Each country blamed the other for being a greater polluter, never wanting to clean its own Augean stables. Year after year, there were foreboding studies that announced imminent doom of the planet if countries did not clean up the environmental mess. Countries met, they bickered and blamed each other, and dispersed.

“Monday morning blues” was the litany of all working people. I remember beginning to feel the blues just when Sunday dawned. Why can’t weekends be longer, was the refrain echoed in all corners of the world – languages varied, refrain the same.  “Let all days be Sunday,” said the mighty voice. And we all huddled home every day, day after day. Beautiful day-planners lying on the desk were an investment most futile!!

Don’t blame any virus or any government for the pandemic…..all wishes are coming true. Is it self-fulfilling prophesy, or mere Ignis Fatuus!  Is it a passing phase, or the new world order is here to stay. Only time will tell.

One thing is for sure. The virus is not atemporal. It may either gradually die a natural death after peaking, or human intervention will see it rendered less menacing. Whatever it may be, but it surely will have taught us the much-needed and long-forgotten basic lessons before it exits.

First and foremost, Covid19 has added the fundamental “Pause” button to human race – race, both as noun and verb – the former defining the species, and the latter their feverish scurrying forth. I feel it has made us stop as the traffic light gradually turns red, so that we have time to reflect until it turns green and hence signal us to recalibrate our speed and direction.  We were all racing from morning until night, 24X7, in pursuit of something that was always outside our grasp.  Were we not all running away from life, looking for a meaning in a place it did not exist.  And now, staying within the confines of our homes we are learning to live with ourselves. Most friends and family I have spoken to have expressed how little we actually need in life and yet we carry the heaviest baggage. Our priorities had gone misplaced and it is time to set them right.  

What is of utmost importance is human life. This lesson, unfortunately, a deadly virus had to come and teach us. It has showed us that we need to value people and use things when we had been doing the reverse – Valuing things and using people. Time for some reverse-engineering. Time to smell the coffee!

People in lock-downs, living away from families learnt the value of a family, and those locked with their families are learning to share, care, and the biggest of all, to let-go. Sharing limited home space has strained many a family, for the virus leaves no option of quietly slipping away from home in case of any friction.  And therein lies the lesson of developing tolerance. “Love me when I deserve the least because that is when I need the most,” my friend’s recalcitrant teenager told his mother. Mighty lesson that is! Equally relevant for the youngster and his mother.

“It would seem resourceful, perhaps wise, to use suffering as a vehicle of transformation that allows us to open ourselves with compassion to those who suffer as we do, or even more than we do”, said Matthieu Ricard in his book Happiness. Roman philosopher Seneca once said that “Suffering may hurt, but it is not an evil.” Schopenhauer, the German philosopher may have had similar belief when he said that suffering is the purifying process through which alone, in most cases, a person is consecrated.  Sure enough, no one wants suffering and all human endeavor is towards forswearing it. However, it can be argued that while suffering by its very nature is abhorrent but when unable to avoid, we can use it to learn and to change.

While we wait with bated breath for this Covid19 to pass, we can only forget the lessons it continues to teach us – both, at the physical level and at a deeper existential, philosophical level, at our own peril.  In the latter half of this century when it is well behind us, and human race has the wisdom of hindsight, Covid19 may seem to be the one game-changer humankind desperately needed for course correction.

I started writing this piece when we were, what is now known as the middle of Covid, or the first phas (It may be known differently sometime down the line) . As we are a cat’s whisker away from getting the vaccine, these disembodied times however seem  here to stay for a while. I’m quite inclined to close with Hafiz : “I wish I could show you, when you are lonely or in darkness, the astonishing light of your own being!” So instead of taking a world trip, go inside yourself and find the true essence. Nice things, beautiful scenic places, gourmet food and all the pompous pursuits of men are a happy place to be in, but the joy they provide is never ever-lasting. It is transitory. The value of things is only the value we ascribe to them. As Vivekananda said: “Things are dead in themselves. We breathe life into them, and then we either run after them or run away from them.”

Covid-19 has provided a big insight into what really matters in the race we call Life. The Pause-button ought to make us reflect on where we were headed, and which direction we need to take. Almost a year into the pandemic, the self-importance of man dissolves in laughter. Life will never be easy. It will always be hard, but we can choose our hard wisely. Look to the light within, for the more light you allow within you, the brighter the world you live in will be.

“Lack Of Investigation may Give Surprise, But Lacking Design Definitely Results In Failure” – Proved Yet Again In Punatsangchhu – II HE Project

– The Case History of Massive Crown Failure In The Huge Cavern. A Perspective Explained Citing Facts, Figures, Analysis & International Technical Literature Of Renowned Authors

A huge cavity of the size of a football field and a height of one third of the height of Eiffel Tower formed through the crown of the 314m(L)x 19m(W) x 58.5m(D) underground cavern of the Downstream Surge Gallery (DSG) of Punatsangchhu-II H.E. Project (1020MW) in Bhutan (PHEP-II), at the time when the cavern was under excavation for 3 years and had been yet excavated to a depth of 35m to 40m. The  failed reach of the DSG, assessed originally as ‘fair to good rock mass’, is actually comprising highly jointed and fractured rock-mass of class IV & class-V and acted as the  hanging wall formed by the major shear zone with 55ᵒ dip and containing a number of smaller shear zones, which intercepts the DSG and its two adjacent caverns of the PH Complex, throughout their depth. This Shear zone remained unexplored in the original geological assessment.

The Punatsangchhu-II  (PHEP-II), a 1020 MW project with scheduled date of commissioning of year 2017 at cost of Rs. 37778 millions, new approved project cost of Rs. 72900 millions ( US $ 1.04 billions), expects further escalation in its cost to Rs. 80000 millions    ( US $ 1.14 billions), with already incurred cost of about Rs. 65880 millions, is delayed due to the huge rock mass failure in its underground Downstream Surge Gallery (DSG), resulting in a huge cavity of about 91m height x 70m length and 45m width in the crown of the DSG. The Dam foundations had  encountered, a thus far unexplored, mega shear of maximum 30m width, cutting across the length all the 4 dam blocks diagonally. The shear zone with its about 35ᵒ to 45ᵒ dip, continued under the foundations to large depths.

There is a strange coincidence of massive geological surprises and huge rock mass failures, which  happened in the two mega hydroelectric projects named Punatsangchhu -I & II H E Projects, under construction since 2009 -10 in Bhutan.

Occurrence of too many geological surprises, the apparent cause of the big mishaps in the two mega Projects, in fact may be a case of  ‘ harping on the geological surprises’ as  a scapegoat for the lack of proper geological investigations carried out by the Main Consultants for geological assessment to be done by their retained Geology Consultants  and inappropriate designs carried out by their retained Designer Consultants.

1. CHANGE  FROM  A SURFACE POWER HOUSE TO UNDERGROUND POWER HOUSE

Originally in the DPR, the Power House Complex was contemplated to be a Surface Power House, to be located on the right bank at a site  3km downstream from the present location of the Underground PH Complex. The change of PH Complex to underground site selected by the Consultants was based on limited exploration apparently through one borehole DSC1 only as reportedly the additional borehole DSC3 was driven  by the Consultants at a  different far away location to  that was suggested by their own Geology Consultants and the same  did not even penetrate through level of crown  of DSG and ended much above it besides that the hole was not properly located.

The change of location of the PH Complex to the underground site was made just before the start of construction  in 2010. The significant observation by the Geology Consultant, in their geotechnical assessment were stated that,  “Rock mass conditions of only limited reach in the DSG have been explored”.

2. GEOLOGICAL ASSESSMENT OF THE UNDERGROUND SITE OF PH-COMPLEX WAS BASED ON AN INADEQUATE GEOLOGICAL INVESTIGATIONS DONE BY THE CONSULTANTS

The  location of the additional bore hole DSC3 for the DSG, suggested by the Geology Consultant and drilled during investigation of the site by the Main Consultants,  was drilled at a wrong location. The Geology Consultant had in-fact reported that the location of the inclined exploratory hole DSC3, drilled above DSG for geological investigations was not the same as what it had advised to and required from the Consultants. 

Thus the rock mass  in the DSG crown was not explored at the particular specific location suggested by the Geology Consultant. Also therefore the rock mass comprising the 58m high walls of the DSG too remained to quite an extant unexplored at the location desired by the Geology Consultant.

The Geology Consultant in-fact had reported, in 2010, on the geo-technical investigations done by the Consultants , that less information about the  DSG  is available for the selected  location of power house complex of Punatsangchhu-II H.E.P.

The Geology Consultant’s report stated, “PH Complex is intruded by a number of pegmatite and leucogranite veins/bodies. Five joint sets are prominent which are open to tight in nature, filled with clay and rock flour. The rock in the major reach of PH, TH and DSG cavern is inferred to be FAIR TO GOOD rock as per Q system. Shear/highly fractured zones may be encountered in the Downstream Surge Gallery cavern”. IT further strongly recommended to ” MINIMIZE THE SIZE OF SURGE CHAMBER AS FAR AS POSSIBLE“.

* Therefore as a result, the location of the underground DSG was  fixed by the Consultants, based on a geological assessment  drawn from a very limited exploration. The geological assessment,  later during the excavation, was actually found to be a grossly wrong .

Tender Drawing of Geological Section Through PH Complex	Tender Drawing of Geological Section Through DSG – Showing the only sole Bore Hole DSC1 being the basis of geological Assessment

Tender Drawing of Geological Section Through PH Cavern Showing Bore Holes PH-1, PH-2, and PH-3	Tender Drawing of Geological Section Through TH Cavern

It may be seen that Tender Specification Geological Drawings Show No Presence of Mega Shear Zone, Which Was Later Encountered During Excavation and was found cutting across the three caverns through out their full depths.

3. PROGRESS OF EXCAVATION IN PH-COMPLEX BY FEBRUARY 2016

The underground powerhouse complex comprises three large caverns viz. Power House (241m x 23.9m x 51m), Transformer Hall (216m x 14m x 26.5m) and Downstream Surge Gallery (314m x 19.8m x 58.50m) on the right bank of Punatsangchhu River. Excavation of Transformer Hall cavern had been completed  to its final depth at EL ±582m, whereas, in Power House/ Machine Hall cavern it was about to completed. The foundation of Turbine Pit -1 with its bottom at  EL ±555.84m had already been achieved and rock covering had been done in the Pit. Prior to collapse, excavation of the Down Stream Surge Gallery (DSSG) had reached maximum up to EL ±578m  in reaches beyond RD ±210m and in rest of the reaches it was at EL ±593m, including  in the failed zone. The DSSG is aligned at N10ᵒE direction for which excavation started in the month of April 2013 by executing its central gullet at its crown  at EL ±623.70m, followed by widening of the crown which completed in the month of August 2014.

Initially the proposed length of the DSSG was 210m. Later on, it was extended up to 314m. In the first phase it was excavated from RD 0m to RD 210m  with its crown at EL ±623.70m and in the second phase benching was carried out from RD 0m to RD ±210m from springing EL ±615m. The excavation of heading of  remaining length of the DSSG,  from RD ±210m to RD ±314m, with its crown at EL ±613.70m, was carried out simultaneously.

4. ACTUAL GEOLOGY ENCOUNTERED

The rock mass encountered in the DSG comprises quartzo-feldspathic gneiss, biotite micaceous quartzite with leucogranite and pegmatite patches and veins. Generally due to intrusive nature pegmatite occurs in the form of veins along joints, whereas leucogranite is present in the shape of patches/bands across or along parent rocks. At places leucogranite/pegmatite is crushed / sheared and fractured due to deformation/folded rock strata. In general foliation has gentle dips 10ᵒ-25ᵒ / N205ᵒ-240ᵒ direction and variation in the attitude of foliation is mainly attributed to warping and minor folding. The rock mass encountered in the central gullet falls in class III (40.00%), class IV (50.95%) and class V (9.04%). The class V (Q= 0.19 – 0.58) rock mass mainly occurs in the major shear zone and its vicinity. Major geotechnical problems which were encountered, were occurrence of major shear zone (45ᵒ-60/N030ᵒ) and formation of cavity in the crown during excavation central gullet (RD ±121 to RD ±129m), low dipping foliation joints posing slabbing conditions in the crown portion, erratically occurrence of intrusive bodies of variable dimensions, minor shearing along foliation joints and other joints at few locations. Besides presence of water (seepage/dripping) along shear zone and ingress of water on the right wall between RD 308m and RD ±313.5 (EL ±599m) were main problems.

ROCK MASS CATEGORY ACTUALLY ENCOUNTERED IN THREE CAVERNS :

CAVERN	FAIR TO GOOD	POOR TO FAIR	POOR	VERY POOR
PH CAVERN	NIL	44.8%	54.07%	1.12%
TH CAVERN	NIL	35.65%	56.94%	7.4%
DSG CAVERN	NIL	40.0%	50.95%	9.05%

• The rock type actually encountered was ‘very poor to poor and poor to fair’ instead of ‘fair to good’. The same is also confirmed by Norwegian Geotechnical Institute (NGI).
• Geology Consultant’s Assessment Report missed the  Shear Zone encountered in central gullet of DSG from RD ±121m onwards dipping 45ᵒ -60ᵒ  due N30ᵒ-35ᵒE having thickness ~1.5m-3.5m. The Q value in shear zone reach, from RD  ±121m to RD 135m,  has been  0.2-0.58 (Class-V).
• Actually DSG encountered 14 nos. of Shear Zones of  size 2cm to 3.5m in contrast to only 2 nos.  assessed of size 2cm to 60cm.
• 5 nos. of Major Joint Sets including Foliation joint with low dip & direction 10ᵒ-15ᵒ :  SW to NW,  spacing 0.02 t0 0.3m. Joints, adversely oriented for wedge actions have continuity 10m to 15m  are generally altered and stained and showing warping.

Shear Zone Intercept in DSG U/S Wall From RD 130m to RD 180m	Shear Zone Intercept in DSG D/S Wall From RD 130m to RD 180m

• The major shear zone (45ᵒ-60ᵒ/N030ᵒ) encountered at the crown portion between RD ±121m and RD ±140m and extending on the either wall dipping towards face (gable end wall) is shown above.

• The hanging-wall portion of the DSG, in its in-situ conditions is propped up by the major shear zone. The Shear Zone reach, from RD 121m to RD 140m, is formed of the rock mass of class- V and the hanging-wall reach beyond RD 140m to RD155m comprise Class-IV, having predominantly Leucogranite with micacious quartzite, biotite gness & pegmatite veins/ bands. Rock mass in this reach is highly jointed and fractured having joints of 10mm to 20mm opening which are  filled with clay / crushed material.

5. OVER EXCAVATIONS DURING EXCAVATION OF THE CENTRAL GULLETS IN THREE CAVERNS

Water seepage in the shear zone which further lowered the shear parameters resulted in  cavity formation of ~2-7m height in the central gullet of DSG with range of cavity of about 1.55m~ 3.05m at RD 117.0m to 7.87m~7.96m at RD 125.0m to 1.5m~3.5m at RD 138m . Rib supports in the central gullet in the shear affected reach have been provided along with  rock bolts of 8m/10m long followed by, additional rock bolts of 12m length provided after installation of rib supports and their back filling and grouting  for the full section, as per Designs. Over breaks in these reaches during widening of the Central Gullet remained of the order of  1.0m to 3.0m 0nly.

However, the range of maximum over break in the DSG from RD 138m onwards was of the order of height of only  1.5m to 3.5. This reach from RD 140m to RD 210m is the reach where, later after three years, the huge rock fall has occurred. Incidentally the location of the 8m cavity ,which happened earlier in April 2013,  between  RD 117m to RD 125m  in the DSG,  when Shear Zone was exposed in the Central Gullet of the DSG, has remained intact and unaffected from the huge rock fall that happened on 03 March 2016.

The reach of the DSG from RD 140m to RD 210m , which suffered massive rock fall, had witnessed only 1.5 m to 3.5m of over excavation that too only during the excavation of the Central Gullet, as compared to the locations which are intact despite suffering much higher order of over excavations of 8m to 14m in PH and TH caverns and even RD 124m in the DSG itself.

In TH,  from RD 84.5m to 95m and then from RD 144.5m to RD 164m, the  over excavation ranged from 0m to 5.7m. It ranged from 0m to 5.7m, from RD 175m to 183m and the over excavation in TH   it ranged from  0.24m to Max. 7.5m  and  from RD 190.5m to 207m it ranged from 0m to 13.95m

In PH from RD 116m to 126.5m the over excavation ranged from 0.8m to 3.5m, from RD 137m to 142.5m ranged from 0m to 4.2m , from RD 150m to 159.5m ranged from 0m to 8.2m and from RD 171m to 175m ranged from 0m to 3.8m.

Thus TH and PH caverns experienced much  larger sized over excavations i.e. of the order of height of 8m to 14m as compared to the almost entire reach in DSG where the over-excavations remained limited to the order of height of only 1.5m  to 3.5m. Both TH and PH through out their entire lengths including locations of as high over excavation as 8m to 14m , with multiple large openings in their walls, are intact .

The only different feature being that the DSG is intersected by the Mega Shear Zone in its crown and also it cuts through entire 58m depth of its walls. The Toe of the Shear Zone got removed during excavation of DSG. Whereas both in the TH and PH Caverns , the Shear Zone is confined and embedded in the Gable End. It does not pose danger in the PH & TH caverns of removal of toe of the Shear Zone there, like the way DSG witnessed it.

• The incidents of over excavation have occurred due to extensive presence of pegmatite veins/ bands and low dipping Foliation joint with dip & direction 10ᵒ-15ᵒ . Excavation in many continuous reaches had not required blasting or was applied with least charge of 0.19 to 0.55 kg/m³. Rock fall due to slabbing action were happening repeatedly .

Incidents of over excavations get explained by the International Research :

* INTERNATIONAL LITERATURE WARNS THAT THE STRUCTURALLY WEAK GEOLOGY IS PRONE TO UNAVOIDABLE OVER EXCAVATIONS

Reference : Forty Years with The Q-System in Norway and Abroad  by Nick Barton Eyestein Grimstad :-

• “In underground excavations if the ratio of JN/JR ≥ 6 is encountered ,over breaks are extremely likely to occur despite  contractor’s best efforts with careful blasting.”

• In PHEP-II PH Complex  caverns the  Jn/Jr = 9 to 12
• This explains tendency of over excavations despite use of controlled blasting using charge factor of only 0.6 to 0.8 kg/m³ & even when at many locations merely scooping was used for tunnelling in central gullet.
• The presence of numerous and  adversely oriented  clay filled joint sets in combination with sub-horizontal foliations and rock mass intervened  by pegmatite was bound to result in uncontrolled over breaks.     

6. DESIGNED ROCK SUPPORT MEASURES

Rib supports in the central gullet which were extended to full section after side slashing, were provided  in the entire reach of all the three caverns of PH, TH & DSG.  The rock support measures thus provided  as per construction drawings  comprise SFRS 200mm thick, 8m/10m long rockbolts  and ISMB350 steel ribs @ 0.5m spacing with backfilling of concrete and  grouting in the crown for the full section, as per the Designs .

The selected reaches of over excavation were provided by additional  rock bolts of 32mm dia and 12m length as advised by  the  Designers.

The shear zone and its associated zone reaches, in the DSG walls, where it has been  exposed, was treated providing concrete cladding, 12m long rock bolts and grouting as per the construction drawing.

• However whether this designed treatment was sufficient to strengthen the rock pillars , provided of just 40m thickness, between multiple caverns situated adjacently and moreover when the pillar is intersected critically throughout its depth and thickness by a mega Shear Zone . The intercept of the Pillar by Shear Zone would have made it a cracked pillar. This Question was best to be answered if and only if a scientific 3D Numerical Analysis of the underground PH Complex would have been done by the Designers incorporating actual geology. However, apparently the analysis was not done by the Designers at that stage.

7. SINKING OF RIBS OBSERVED IN NOVEMBER 2014

During widening of DSG from RD 117.5 m to RD 132m, rock bolts could not be installed immediately after excavation,  as the holes were getting collapsed during drilling. hence in order to mobilize immediate rock support, support system of 200mm thick SFRS and Built-up section as per construction drawings were provided and backfilled in this reach. Side slashing /widening of Machine Hall, Transformer Hall and & DSG had been done by adopting controlled blasting and charging technique i. e line drilling, alternate charging of periphery holes. The charge factor observed at site ranged from 0.6 to 0.8 kg/m3 which was considerably low. The rock bolts/wedges had got  detached during widening thereby affecting the crown profile and arching action of roof caverns. At some locations in Class III reach of central gullet of these caverns, rock bolts got exposed after loose fall during side slashing. As reported, the geological features are uncertain and of intrusive nature with pegmatite veins, leading to frequent rock fall and accident to men and machinery.

In view of all the above and considering permanent stability of these caverns, it was requested to Consultants a number of times, in fact 29 times between May 2013 to   dated 23.12.2013 to suggest adequate supports at the crown of all these caverns before start of excavation in Benching .

During November, 2014, at El. 618.08m, a gap of 55mm had been between ribs and cladding on the D/S wall of DSSC at RD 130m to RD 170m  at the location of shear zone  and that of 20mm on the U/s wall at RD 170m to RD 180m. The surface target installed on D/s wall showed  a sinking of 20mm at springing level. The reaches were cement grouted as advised by the Designers / Consultants after observing no further increase in distress.

Time History Plot Of Displacements Of Crown At RD 135m :

Plot of X- Displacements	Plot of Y- Displacements	Plot of Z- Displacements

Time History Plot Of Displacements  At El. 620m in Upstream Wall At RD 135m

Plot of X- Displacements	Plot of Y- Displacements

Time History Plot Of Displacements  At El. 620m in Downstream Wall At RD 135m

Plot of X- Displacements	Plot of Y- Displacements	Plot of Z- Displacements

It may be observed from the Time History Plots of Displacements at Crown Level and El. 620m in both Upstream and Downstream Walls of the DSG at RD 135m ( shown above)   that a sudden displacement in all the three directions were first noticed on 29 November 2014 in the BRT Surface Target Installed (Location of Target in Crown Shown as Yellow colored in Fig. – 8 below). The displacement kept increasing with sudden sharp increments along progress in Benching.

However, around  November 2014 , the location of progress of the excavation in Benching in the reach surrounding  RD 135m coincided with the location of occurrence of Shear Zone at the level of Springing of the Rib Arches supporting the crown of the DSG Cavern (Refer Fig. -8 below).

Benching Excavation In Shear Zone Intercept Reach – D/S Wall of DSG – During Around November 2014	Benching Excavation In Shear Zone Intercept Reach – U/S Wall of DSG – During Around November 2014

8. MAJOR MISTAKES COMMITTED OF NOT TAKING APPROPRIATE MID-COURSE CORRECTIONS IN THE LAYOUT & SUPPORT DESIGNS, RIGHT AT THE STAGE OF START OF BENCHING EXCAVATION, DESPITE BEEN SUGGESTED THE CORRECTIVE MEASURES, AS EXPLAINED BELOW

8.1 The Suggestion Given By The Geology Consultants  To  Keep Size Of DSG Cavern Smaller By Adopting A Network Of Tunnels And Galleries Of Smaller Size, Was Not Adhered To : 

The Geology Consultants had categorically advised  to the Main Consultants and the Designers in their 2010 report that, “The Shear/highly fractured zones may be encountered in the Downstream Surge Gallery cavern” and therefore MINIMIZE THE SIZE OF SURGE CHAMBER AS FAR AS POSSIBLE“.

* INTERNATIONAL LITERATURE WARNS THAT POOR GEOLOGY WITH ROCK MASS RATING BELOW 50,  IS  NOT SUITABLE  FOR LARGE CAVERNS

Reference : UNDERGROUND EXCAVATIONS IN ROCK by HOEK & BROWN (Page 299):-

• “The stability of the rock in immediate vicinity of the underground openings in deeper excavations depends upon behavior of the entire rock mass surrounding these openings.
• This rock mass may be so heavily jointed that it will tend to behave like an assemblage of tightly interlocking angular particles with no significant strength under unconfined conditions.
•  Therefore Large caverns should only be excavated in rock with adjusted total classification ratings of 50 or better “

* The  RQD rating for the DSG stands evaluated of the order of 40 only, which is not favorable for excavation of caverns with larger sized depth. Geological Consultant had also cautioned in their investigation report to not provide large  sized DSG.

• However, the Designers / Consultants had provided 314m long x 19.5m wide x 58.5m high single large cavern of the Downstream Surge Gallery (DSG) against the advice of the Geology Consultants.

• The Designers should have reviewed the size of the DSG after the Shear Zone was detected to be intersecting the DSG in its entire depth and relocation of the DSG was not seen possible by them.   However the Designers ignored a request made by the Project Management to adopt a set of smaller chambers which shall be interconnected by a network of tunnels. After the rock fall in the DSG, it has become necessary and is being done so to redesign the DSG layout comprising additional smaller chambers and tunnels which make up for the lost volume of the abandoned reach of the DSG.

8.2 Results Of Numerical Analysis Informed To The Consultants Indicating Potential Extensive Yielding In DSG Walls In Shear Zone Affected Reach Was Ignored :

After, the gap of 55mm that occurred between ribs and cladding on the D/S wall of DSSC at RD 130m to RD 170m  at the location of shear zone  and the gap of 20mm on the U/s wall at RD 170m to RD 180m, in the DSG at El. 618.08m along with  sinking of the ribs by 20mm at springing level in the November, 2014, the Contracting Agency responsible for construction of the Power House Complex had carried out a Numerical Model Analysis of the DSG cavern. The analysis established that when the DSG excavation reaches 2/3rd of its depth, there would be wide spread yielding of rock mass occurring in the walls of the DSG. It established that with further progress of the excavation to its full depth of 58.5m, the yielding of rock mass would be 100%.

Yielded Zone of Rock Mass in The Rock Pillar When DSG is Excavated to 2/3rd of its Height	Yielded Rock Mass in The Rock Pillar When DSG is Excavted to its Full Height

• The results of the analysis were informed to the Designers Consultants , but they did not agree with the findings of the analysis performed by the Contracting Agency and ignored the same.

8.3 The Suggestion To Provide Wall Beam Over The Shear Zone And Providing Of Cable Anchors Was Not Adhered To:

Based on the findings and results of the above mentioned Numerical Analysis, it was suggested by the Project Management to the Designers to provide Wall Beam at El. 608m. It was also suggested to the Designers to design appropriate Cable Anchors to strengthen the crown and walls of the DSG in the reach affected by the Shear Zone.

• However the provision of Wall Beams and Cable Anchors was not agreed to by the Designers.

8.4 The Layout Design Of The Three Caverns Which Needed To Be Changed To Provide Thicker Rock Pillars Between The Adjacent caverns Was Not Done :

PHEP-I is the nearest located H E Project at 11Km in the U/S of PHEP-II and both have almost identical layout. Incidentally, both PHEP-I and PHEP-II have been contemporary in their designs and construction by the same Designers and Consultants. 

As the rock mass in PHEP-II underground DSG has been Class –IV (poorer, which is further weakened due to its intersection by major Shear Zone at 55ᵒ dip,  in comparison to that of Class – III (better rock class) in PHEP- I, therefore the  Pillar/ wall  width in case DSG of  PHEP-II, logically, should have been kept larger than pillar width  provided in PHEP-I of 40m ( refer Fig. – 1 given earlier above).

                  Further, In case of PHEP-I, the thickness of rock pillar / wall between PH and TH cavern is 52.5m , which is equal to depth of the PH cavern there in PHEP-I. On that lines thickness of the rock pillar / wall between TH and DSG of PHEP-II, logically, should have been 58m i.e. equal to the depth of DSG , instead of the presently provided thickness of 40m.

* The principal of providing thickness of the rock pillar equal to the  depth of the cavern with larger depth of the adjacent two caverns is recommended also by the following International research :

* Reference : Design of large underground caverns – paper by Cheng Y and Liu , Taiwan, – 6th Cong. ISRM, Montreal :

• ” The pillar width between two caverns should be equal to or more  than the depth of the cavern with larger depth  of the two”.

• Out of the adjacent caverns of DSG and TH , the DSG is of larger depth that of 58.5m. Thus the rock pillar between TH and DSG should have been at least 58.5m thick. In fact because a major shear zone is intersecting this pillar, the thickness of the rock pillar provided should have been still bigger than 58.5m was

• However the 40m thickness of the DSG Pillar was fixed or designed, if at all on the basis of some design, it must have been done so,  prior to coming to know of both the actual poor geology and the intersecting shear zone. Therefore 40m thickness of the pillar being already lacking the thickness as stipulated by International Researches, had  in fact become  further weak due to its intersection by the Shear Zone.

• This stand gets  vindicated by the results of the 3D Numerical Model Analysis  done  by an independent agency of repute, to study behavior of the original designed layout of the three caverns under actual geological conditions and without  incorporating any over excavations (Refer Paragraph No. 12 below). The analysis, which had not included any effect of over excavations accounted for, yet establishes that, the DSG walls, along the intercept made by the shear plane,  in fact had already yielded  up to 10m to 15m depth in the 40m thick rock pillars at haunch level of the crown and below, over a large length of the DSG walls,  in the reach RD 140m to RD 210m , in the hanging wall side of the shear zone where throughout  this reach the shear zone intersected  the rock pillars/ walls of DSG. 

• It is certain that  if a scientific analysis was ever done originally by the Designers to fix the layout and thickness of the pillars / walls kept between the adjacent caverns of the underground PH Complex, the safety and stability of the DSG cavern with the provided thickness of rock pillars, under actual poorer geological conditions and the presence of the intersecting Shear Zone, would have been seen to be failing with progress of excavation in benching. 

9. PLOTS OF DISPLACEMENTS AT RD 135m & RD 180m SHOW THAT THE DISPLACEMENTS WERE INCREASING WITH PROGRESS OF BENCHING

Plot of Displacement in the Upstream Wall At El. 620m in the Crown Arch of DSG at RD 135m	Plot of Displacement in the Downstream Wall At El. 620m in the Crown Arch of DSG at RD 135m

Plot of Displacement in the Upstream Wall At El. 620m in the Crown Arch of DSG at RD 180m	Plot of Displacement in the Downstream Wall At El. 620m in the Crown Arch of DSG at RD 180m

It may be observed from the above Plots of Displacements at RD 135m and RD 180m, that the displacements were increasing with the progress of excavation in Benching, despite the walls having been supported with the designed rock support system.

The rock mass in the wall, beside been intersected by major Shear Zone dipping 45ᵒ -60ᵒ  due N30ᵒ-35ᵒE having thickness ~1.5m-3.5m, comprise Quartzo feldsphatic biotite gneiss / biotite gneiss/ micaceous quartzite with leucogranite & pegmatite, minor shear seams , thinly foliated rockmass with low dip[ping foliation (10ᵒ – 25ᵒ / N200ᵒ – 230ᵒ) joint at places.

The general rock support system provided in the walls, as per drawings, comprise  8 – 10m long rock bolt ( 36 mm dia.) @ 1m/ 1.5m C/C & SFRS 200mm thick.

The reach in walls in Shear zone and associated weak rock mass has been supported with concrete cladding and two sets of 15m long 36mm dia rock bolts followed by consolidation grouting. Out of the two sets of rockbolts provided for cross stitching the shear zone, one set of rockbolts driven from South to North direction were ending entire part of their anchorage length in the shear zone/ class IV fractured rock mass. Wire mesh with consolidation grouting has been provided in the vicinity areas of shear zone having fractured / crushed rock mass. At places minor seepage has been observed along shear zone and its vicinity.

10. THE OBSERVATIONS OF INSTRUMENTATION IN DSG

With the Benching progressing deeper, the reach in the Hanging Wall comprising fractured rock mass  suffered subsidence and drifting with increased dilation due to increased depth of excavation.  

• By 31.12.2015  when the benching proceeded to  El. 587m in U/S wall and  to El. 590m  in D/S wall,  the distress observed by MPBX in the crown remained insignificant. While distress in the U/S wall at Rd 135m at El. 609m  got to the order of 5 to 8mm   and that in the D/S wall increased to the order of 13.4 mm. While the distress observed by MPBX at RD 180m at El. 609m in the U/S wall had increased to 21.4mm  and that in D/S wall  had  increased to the order of 27.5mm.

• The important and much significant phenomenon observed is that  ever since the benching had proceeded , the MPBX readings remained insignificant , thereby indicating that the displacement shown by the Surface Target  meant that the rock mass above crown of the DSG cavern  (at least up to a thickness of at least 25m of the rock above crown i.e. up  to end of MPBX length) and the portion of walls lying above the intercept of shear plane, behaved like one  body.
• This upper truncated portion of the cavern separated along the inclined Shear plane and continuing in the walls of DSG towards North  from the shear zone,  had apparently started  sliding  bodily  on the shear plane  which dipped  steeply from South to North direction and also dipped in other plane from U/S side wall to D/S wall.
• The bodily movement of this truncated portion, along the shear plane is evident from the observation that while the MPBX readings remained  insignificantly small,  the Surface Target  observed  movement  had been increasing very significantly.
• The readings  shown by the MPBX instruments  installed near the locations of collapse were almost constant for last 10 months and showed sudden increase in their readings on 02nd Mar, 2016. The reading of instrument  installed at RD 135 at crown level (centre of the cavity) at El. 623.5m which was also constant till 01st March 2016 showed sudden increase  from -0.5 mm to -1.0mm at 25m depth, -0.6mm to -36.7mm at 15m depth, -0.5mm to-27.5mm at 10m depth and -0.9mm to -9.8mm at 5m depth.
• On 02.03.2016, the crown at RD 135m had drifted in direction from U/S to D/S walls  by 36mm , had sunk by 46mm  and drifted in direction from South to North direction by 20mm along the two dip directions of the shear plane.
• At this time, on 02.03.2016 at RD 135m in crown the distress recorded by MPBX too had suddenly  increased from less than 1mm earlier to 36.7mm sinking and at around 1.00am , the crown apparently due to failure of arch toe at SPL and below in a reach in which the Shear Plane intersected walls.

11. THE MASSIVE ROCK FALL – HAPPENED ON 03 MARCH 2016

Massive rock mass failure happened from crown in Downstream Surge Gallery (DSG) between RD ±140m and RD ±210m, apparently, along a major shear zone (45ᵒ-60ᵒ/N030ᵒ) encountered at the crown portion between RD ±121m and RD ±140m and extending on the either wall dipping towards face (gable end wall). The failure of rock mass took place within a short period, starting on 3rd March, 2016 around 1.00am, leading to formation of huge cavity above crown. Six technicians working, at the time of the rock fall,  in the DSG at locations between RD 140m to RD 210m, got buried under the falling rock muck and died. Bodies of only 3 of the dead were retrieved after removal of some muck from the toe of the piled up fallen muck.

The  loose fall from cavity had not stopped completely after the collapse on 03 March and intermittent loose fall continued for some three weeks.  Rock After 03 March, the other loose fall from cavity had been recorded on 11/03/16 (Photo-2) and 22/03/2016. A portion of the cavity and hanging rock bolt became visible through a gap formed, after muck from top of the heap rolled down when some rock muck was removed from bottom at toe of the heap (Photo-3) in making efforts to retrieve dead bodies of the entrapped persons. The impact of the rock fall incident had been noticed in the nearby caverns/structures in the form of development of new cracks in the shotcrete, widening of already existing cracks particularly on the right wall of TH and Bus Ducts nos. 2 and 3.

The construction Adit opens in the southern side of the DSG.  The northern side of the DSG did not have any independent access.  The northern half of the DSG got cut off from the southern side of DSG as the fallen muck blocked the DSG at RD 140m. Ten technicians who were working in the northern end of the DSG at the time of rock fall, miraculously escaped, after climbing the 45m high rock muck  heap, from the small opening left at the top of the heap. However the small opening from where these ten technicians escaped had got blocked with further rock fall soon after they escaped.   

The fallen rock mass comprises variable size of fragmented rock pieces, sandy clay and dry clay fractions with big rock blocks (max. size ~9.0m x 1.5m x 3.0m).  This clearly indicates that failure of rock mass is not restricted to only shear zone and its associated weak material, but the rock fall  has been resulted from the  loose fall, controlled by the gravitational forces acting on the blocks of rock comprising the rock mass and making them fall down as these disintegrated from adjoining blocks for being  held together only weakly due to presence of clay content and crushed material in their joints and due to presence of intrusive pegmatite veins / bands.

12. THE  ASSESSMENT OF THE SIZE & ORIENTATION OF THE CAVITY FORMED

The size of the cavity and its orientation  was assessed from a number of exercises including Seismographic Tomography, Lidar based Cavity monitoring using CMV 500 camera lowered from two number of 250mm dia holes drilled from ground surface above the location of cavity and a few holes done from the Cable Tunnel running parallel to the DSG.

The above mentioned studies revealed that the massive rock mass failure which took place in very short time, did lead to formation of a  huge cavity of 91m height x 45m width x 70m length  above crown of the DSG Cavern.

3D View Sketch Of The 91m High x 70m Long x 45m Wide Cavity Formed Above DSG Cavern	Result Of Assessment Of The Cavity By Tomography

13. A Thorough Analysis Was Required To Check The Design Of  Layout Of The Three Caverns For The Structural Stability, Under Conditions Of Actual Geology Including The Mega Shear Zone. If It Had Been Done Before Progressing With Excavation In Benching, It Would Have Established That Deeper Excavation Would Result In Widespread Yielding Of Rock Mass & Collapse : 

The rock mass in the DSG in the Hanging Wall side of the Shear Zone in the DSG comprise thinly foliated, highly fractured biotite gneiss and crushed leucogranite/pegmatite.

A 3D Numerical Model Analysis done by an  independent agency of repute has established that the rock mass lying over the Shear Plane from RD 145m to RD 195m  suffered yielding, up to a thickness of about 10m to 15m inside the rock Pillar and the walls, while the DSG had been excavated only to  about 45m of its full depth of 58.5m.

Rock Mass in DSG Pillar Yielded Up To 15m Thickness At RD 145m	Rock Mass in DSG Pillar Yielded Up To 15m Thickness At RD 155m	Wide Spread Yielding Of Rock Mass Around DSG At RD 195

Wide Spread Yielding Of Rock Mass Around DSG At EL. 600m	Wide Spread Yielding Of Rock Mass Around DSG At EL. 610m	Wide Spread Yielding Of Rock Mass Around DSG At EL. 620m

14. The Possible Explanation Of The Phenomenon Leading To The Massive Rock Mass Failure 

• Surface BRT Readings v/s MPBX Distress Readings At Crown At RD 135m:

• The reading of MPBX instrument  installed at RD 135 at crown level at El. 623.5m which was constant till 01st March 2016 showed sudden increase  from -0.5 mm to -1.0mm at 25m depth, -0.6mm to -36.7mm at 15m depth, -0.5mm to-27.5mm at 10m depth and -0.9mm to -9.8mm at 5m depth, When the Surface BRT Instrument showed the crown having displaced in X-Direction from Upstream to Downstream wall side by 36mm, Y- Direction (Settlement) by 46mm and Z-Direction towards Northern Gable end by 20mm .

Surface BRT V/s MPBX Readings At EL. 620m In Crown At RD 135m In Upstream Wall	Surface BRT V/s MPBX Readings At EL. 620m In Crown At RD 135m In Downstream Wall

The reading of MPBX instrument  installed in the crown arch at RD 135 at El. 620m in Upstream Wall which was not very significant  till Jun 2015 started increasing  thereafter and became quite significant by Oct 2015 and the distress still increased reaching to the order of 20.5mm  and in the Downstream wall side MPBX at El. 620m at the RD 135m the distress which was insignificant, it  increased suddenly on 02 March 2016 to 11.6mm, When the Surface BRT Instrument showed the the arch at El 620m  having displaced in X-Direction Upstream to Downstream wall side by 27mm, Y- Direction (Settlement) by 96mm and Z-Direction towards Northern Gable end by 16mm .

* Reference : Under Ground Excavations in rock by Hoek & Brown/ page 210

• “In case of an inclined over-body, the shear stress being parallel the dip of the over-body, gives rise to asymmetrical stress distributions. This asymmetry is even more pronounced  when excavations are influenced by gravitational loading (from structurally poor rock mass matrix)”.  
  • Norwegian geotechnical institute, which was assigned to suggest strengthening measures after rock mass failure,    has in its report mentioned that “in the area of cavity in DSG ( i.e. Shear zone affected area),  the pillars are more loaded” . (i.e. Indicating loaded beyond their capacity )

It has been noticed that in the shear zone thinly foliated, highly fractured biotite gneiss and crushed leucogranite/pegmatite is exposed particularly on the left wall near SPL at RD 124m to RD 140m . Further at the crown near RD ±170m blocky and jointed rock mass is exposed.The rock mass quality in PHEP-II is  Poor to Very Poor  formed of  fractured and blocky rock mass comprising Quartzo feldsphatic biotite gneiss / biotite gneiss/ micaceous quartzite with leucogranite & pegmatite, minor shear seams , thinly foliated rockmass with low dipping foliation (10ᵒ – 25ᵒ / N200ᵒ – 230ᵒ) joint at places. The major shear zone (45ᵒ-60ᵒ/N030ᵒ) encountered at the crown portion between RD ±121m and RD ±140m is extending above the crown and below on the either wall dipping towards face (gable end wall).

• The massive rock mass failure took place in very short time leading to formation a huge cavity above crown (Fig. – 11). The fallen rock mass comprises variable size of fragmented rock pieces, sandy clay and dry clay fractions with big rock blocks (max. size ~9.0m x 1.5m x 3.0m) which clearly indicates that failure of rock mass is not restricted only to shear zone and its associated weak material. 

* It can be explained  that the shear zone material and associated weak rock mass fell down first. Later on the jointed and blocky rock mass, which was abutting  along the plane of the shear zone and structurally being just an assemblage of rock blocks,  it was bound to slide/fall down under its  gravitational force due to removal of  its toe. Large blocks of parent and intrusive rocks fell down (intermittently) for the last 20 days resulting into formation of huge cavity (±50m) above the crown (EL ±623.70m) tentatively between RD ±130m & RD ±170m. The lateral and vertical extension of cavity towards gable end wall is because of slabbing and wedge.Large blocks of parent and intrusive rocks kept falling down subsequently as the cavity propagated in its height to 91m, in length to about 70m and in width to about 45m.

• The Norwegian Geotechnical Institute has mentioned in its findings that the ribs do not show any sign of deformation and the rock pillars are more loaded. The fact that failed/fallen ribs do not show any sign of deformation (bending/shearing/twisting), clearly indicates that ribs have failed due to sudden impact of overlying dead load, which was resulted from settling of the yielded rock mass in the Pillars and thus failing the toe of the ribs at SPL.

• The toe of the ribs rested on the yielded rock pillars which were already weak because of their provided thickness of 40m only, which was less than the  norm of thickness advised by International Research Papers and as such required to be 52m. Further the pillar were weakened by the intersecting mega shear zone. Therefore with the sudden impact of sudden development of the dead gravitational load in the crown due to sinking of its supports , the toe at SPL of the ribs failed.

15. THE CRUCIAL REVIEW WHICH WAS MISSED BY THE DESIGNER/ CONSULTANTS, WOULD HAVE WARRANTED SHIFTING OF DSG OR ALTERING ITS LAYOUT TO AVOID ITS INTERSECTION BY THE SHEAR ZONE

A critical decision about the site of the PH Complex, which was required to be reviewed by the Designer / Consultants at the time when the site conditions and the encountered geology were reported to the Designers/ Consultants time after time, is discussed below citing reference from the International Literature of the renowned author : 

Conceptual Visualization Of Shear Zone Cutting The Hill

15.1 The Shear Zone encountered in the Construction Adit of DSG & Main Access Tunnel to the PH Cavern  earlier in 2013 were indicative of its intersection of the three caverns :

The shear zone along which apparently, the failure of rock mass has taken place had been identified prior to excavation of DSG and it was delineated in Adit to DSG (at RD ±440m) and Main Access Tunnel (at RD ±420m) in the year 2013.

15.2 The same shear zone when was encountered in the crown of DSG between RD ±121m and RD±129m, the Project Authority advised the Designers / Consultants to shift the location of all the three caverns of PH, TH & DSG to avoid their intersection by the Shear Zone :

During excavation of central gullet of DSG the same shear zone was encountered in the crown of DSG between RD ±121m and RD±129m at crown level (EL ±623.70m). The Resident Geologist, at that time, made an assessment of the intersection  of  this major shear zone and influence of its associated zone. Taking note that the  steeply dipping Major Shear Zone will be cutting the PH and TH that too for their entire depth, the Project Geologist suggested for shifting the location of all the three caverns, to avoid their intersection by the Shear zone.

However as per the instructions of the Designers / Consultants,  only the Machine Hall and Transformer Hall caverns were shifted towards backwards (N190ᵒ direction). Along shear zone water seepage had also been recorded (central gullet) which had lowered the shear parameters. The shear zone (attitude; 45ᵒ- 60ᵒ/N030ᵒ) has associated rock mass  classified as class V (Q – 0.19 – 0.58). Over breaks of the order of 4.0m to 8.0m were observed between RD ±121m and RD ±129m in the Central Gullet.  During excavation of central gullet a cavity (7m-8m) was formed at crown level and it was back filled with concrete and rock mass grouted  before widening. The entire zone was supported with steel ribs.

During slashing/widening of the DSSC no adverse effect such as cavity formation, distressing in rock mass and disturbance/deformation in already erected ribs were noticed / recorded.

However, during November 2014, when the  benching was progressing in the Shear Zone and its affected zone,  sinking of the steel ribs at SPL line were noticed on the DSG wall near shear zone and it was communicated to  the Designers/ Consultants.  The gap created in the concrete pad and the rock profile in the affected reach was filled back and grouted as advised by the Designers / Consultants.

* INTERNATIONAL LITERATURE WARNS THAT :  “STEEPLY  INCLINED STRUCTURAL GEOLOGICAL FEATURES & FAULTED /JOINTED ROCK MASS MAY WARRANT  RELOCATION”  

* Reference : UNDERGROUND EXCAVATIONS IN ROCK by HOEK & BROWN (Page 10 & 11):-

• ” Instability due to adverse structural geology tends to occur in hard rocks which are faulted and jointed and where several sets of discontinuities are steeply inclined. Stability can sometimes be improved by relocation or reorientation of the excavation but fairly extensive support is usually  required. Rockbolts, dowels and cables are particularly effective, provided that the structural features are taken into account in designing the support system.

• If stability cannot be improved by reorientation / relocation and design of support to prevent gravity falls to reinforce potential fracture zones is not possible, the SITE BE REJECTED. “

• Taking note that the  steeply dipping Major Shear Zone will be cutting the PH and TH that too for their entire depth, the Project Geologist suggested for shifting the three caverns, to avoid their intersection by the Shear zone.
• The Design Consultants shifted only the PH & TH caverns to avoid major Shear Zone from intersecting these caverns.
• Designers still preferred the huge sized single gallery. The site of DSG was neither  rejected  nor  bifurcated or shifted to avoid shear zone and the fractured zone
• Provision of cable anchors suggested by Project Authority for improving structural stability were specifically denied by Design Consultants

CRUCIAL ACTION REQUIRED BUT MISSED WAS:

As the major shear zone was to intersect all the three caverns throughout their entire depth, thus beside  shifting the location of TH & PH, it was also prudent to at least bifurcate the DSG in to two chambers with the middle reach of DSG from RD 130m to RD 180m intersected by shear zone, been left un-excavated. Additionally  small interconnected galleries could be provided to make up for volume lost in thus abandoned middle reach.

16.     IS THE PRESENT SITE OF THE PH COMPLEX OF PHEP-II SAFE  ??

Actually in the DSG which is aligned in North-South direction, the Shear Zone cutting it across, separates a relatively good rock mass occupying in its southern side, from a fragmented rock mass with sub-horizontal foliation, intruded with lenses & inter-bedding of altered & weak material like crushed pegmatite occupying its northern side.

The rock mass in the DSG Occupying its northern side of the partition made by the Shear Zone, behaved like an assemblage of loosely packed rock blocks forming the hanging wall, which when were rendered unconfined along its face abutting the Shear Zone and crown surface , were bound to slide/fall down under its own gravitational load, due to removal of its toe. Large blocks of parent and intrusive rocks fell down (intermittently) for the 20 days resulting into formation of huge cavity (±91m high) above the crown (EL ±623.70m) tentatively between RD ±140m & RD ±210m. The lateral and vertical extension of cavity towards gable end wall is because of slabbing and wedge formations. 

However, the most important point is that after the sudden formation and fast propagation of the cavity to a height of 91m and its spread in about 70m length and about 45m width, the huge cavity and its surrounding rock mass is lying, for more than 4 years, unattended and untreated and without getting strengthened. What would be the condition of the rock mass surrounding the cavity ? The Tomography study indicates that a bigger zone surrounding the profile of the cavity is disturbed.

What should be the extent of strengthening the rock mass surrounding the cavity and the walls of caverns of the DSG, TH and PH so as to make this site safe for about 100 years of  the life of the Project  ??

– Another Dam Location That Too May Go / Have Gone / Could Have Gone Wrong Due To Unexplored Shear Zone Called “Geological Surprise”. Could This Shear Zone, If Went Unexposed, Have Repeated A Punatsangchhu-I ?

( Second of the incidences of a chain of massive surprises in the two Punatsangchhu Projects in Bhutan )

* Are All Geological Surprises, Logical Geo Surprises ?

In the series of strange coincidences of “geological surprises” , which  happened in the two mega hydroelectric projects named Punatsangchhu -I & Punatsangchhu-II H E Projects, under construction since 2009 -10 in Bhutan, the present case is of a suddenly encountered mega Shear Zone, which cuts across from heel to toe, the foundations of four dam blocks, in an effective width maximum of 30m and running in depth more than 13m. This surprise came despite the very dam site having been explored by the Consultants in the DPR ( unlike the case of Punatsangchhu-I dam where a mega shear zone was ‘surprisingly’ encountered supposedly because the dam site was not the one, which was studied by the Consultants in DPR).

• The structural damage control seems to have been done with shear zone treatment , but at a great cost both in terms of the big time delay of more than one year and extra cost of Rs. 387 million, put to the Project in exploring the shear zone and treating it. However, the success of the Shear Zone treatment would be tested with time.

The Punatsangchhu-II  (PHEP-II),  a 1020 MW project with a new approved project cost of Rs. 72900 millions ( US $ 1.04 billions), possibly to be further escalating to Rs. 75000 millions ( US $ 1.07 billions), with already incurred cost of about Rs. 65880 millions is delayed for two reasons. Firstly the delay of more than one year was caused because the Dam foundations had  encountered, a that far unexplored, mega shear of maximum 30m width, which cut across the length of the 4 dam blocks diagonally, traversing from heel to toe. The shear zone with its 35ᵒ to 45ᵒ dip, continued under the foundations to large depths. Secondly, a further delay of four years, so far, in implementation of the Power House Complex, has already crept in due to the huge rock mass failure which happened in its underground Downstream Surge Gallery (DSSG), resulting in formation of a huge cavity of about 91m height x 70m length and 45m width in the crown of the DSSG.           

Occurrence of too many geological surprises, which were blamed for the big mishaps in the two mega Projects Punatsangchhu – I & II ,intrigues one to investigate if ‘ harping on the geological surprises‘ was only a scapegoat for the lack of proper geological investigations done by the Consultants and inappropriate design of rock support measures done by the Designers, who were same for both the Projects.

The Case of  Mega Shear Encountered In PHEP-II Dam Foundations

1. Geology at Dam Site :

Geologically, the area at the dam site exposes variety of gneissic rocks such as quartzo-feldspathic biotite gneiss, banded gneiss, augen gneiss, and thin seams or bands of biotite schist. These rocks are intruded by leucogranite and pegmatite. The right bank is comparatively steeper and occupied by well exposed rock outcrop. Whereas the left bank is largely occupied by overburden consisting of talus and thick slide debris with some rock outcrop exposed at higher reaches. On the left bank foliation trend varies from N-S/40⁰E to N70⁰E-S70⁰W/15⁰SE whereas on the right bank it varies from N80⁰W-S80⁰E-32⁰/S10⁰W to N50⁰E-S50⁰W/30⁰-35⁰ S40⁰E. This swing in foliation is due to warping in the rock. However the general trend of the foliation is N60⁰-70⁰E to S60⁰-70⁰W/30⁰SE. The rocks are moderately to highly jointed, traversed by four to five prominent joint sets and shear zones up to 50cm thick. In general the foliation is dipping into hill side; indicates an anti-formal structure.

2. Geological Investigations at ‘Detailed Project Report’ Stage Failed To Detect   The Major Shear Zone In Dam Foundations

In the DPR stage, in the geological investigations carried out by the Consultants,  a total of 11 nos. of holes were drilled at the proposed dam location for ascertaining the rock-overburden contact and depth of fresh rock for deciding the foundation level of various blocks. On the basis of these DPR stage drill core examination, the deepest foundation was proposed at EL 760.0m by the Consultants in the DPR. No major Shear Zone were detected to be present at dam site as per DPR stage explorations and geological investigations done by the Consultants (See Fig. -1).

3. Geological Investigations At Construction Stage :

Weak features were encountered during dam excavation /stripping of the left bank, which were not reported in the DPR stage investigations done by the Consultants.  Actual rock profile at EL 825.0m, in the Left bank was found shifted by 14.5m towards hill side from that suggested by DPR stage investigations .

In view of this discrepancy a detailed investigation was felt required to be done to ascertain the sound foundation grade rock and to also decide stripping limit. Subsequently, during construction stage, keeping in view the change in anticipated rock slope profile, 12 nos. of drill holes ( See Fig.-3) were drilled at EL 825m to reconfirm the rock overburden contact and foundation grade rock at the dam bloc nos. 1, 2, 3, 4 & 5 located near the left abutment. As the fresh rock was encountered at higher level as compared to DPR stage investigations, the of block nos. 4, 5, 6, and 7 have been founded at EL 765.0m, instead of at EL 760.0m.

            During these construction stage exploratory drilling, on the left abutment, weak rock mass zone with sandy horizon encountered in the DH-10 and 12 ( See Fig. 3). From the drill core logging it had been interpreted that sand and crushed rock pocket exists from EL 763.4m to El 759.40m, however that time direction and inclination could not be confirmed.

The drill holes in the river bed area established to have a maximum depth of fluvial fill material/overburden of 52.50m (DH-9: located in block no. 5, 35m d/s of dam axis). The maximum depth of the quaternary alluvium/overburden in the river valley under the dam axis is 45.60m (DH-14: located in block no. 3, at dam axis).

            General level of the exposed bedrock in the overflow dam section varied from EL 765.0m in dam block no. 4 to EL 755.0m in main dam pit (block nos. 8, 9, 10). The rocks exposed at the foundation grade comprised predominantly quartzo-feldspathic-biotite gneiss, biotite gneiss, and leucogranite. These were intruded by veins of leucogranite, quartz and pegmatite. The foundation rocks were traversed by a number of shear seams and most of them were of short continuity and restricted to a single dam block.

* Still no major Shear Zone was detected in this detailed geological investigations done by the Consultants during excavation of dam pit.

4. Additional Geological Exploratory Drilling Necessitated Yet Again During Further Dam Excavation

As mentioned above, 12 nos. of holes were drilled during excavation stage  in view of the discrepancy observed against the DPR investigations.  A  4.0m thick sand pocket was found resting over highly fractured and crushed rock mass near proposed joint of block nos. 5 & 6 when had been probed during drilling of hole nos. 10 & 12 at RD 87.0m & CH 16.0m & 27.0m respectively below proposed block joint of 5 & 6. Considerable water loss was observed during drilling and sand was first appeared at EL 763.0m during drilling hole no. 10 and continued up to EL 758.5m. The rock strata encountered immediately below sand deposit was found highly fractured and crushed up to the EL 749.90m. The same sand deposit was further reconfirmed through hole no. 12 drilled at RD 87.0m & CH 24.0m downstream where it is appeared from EL 760.27m to EL 758.77m, resting over highly fractured and crushed rock mass up to EL 755.77m. In view of uneven bed rock profile four drill holes were carried out to decipher the sound foundation grade rock below the EL 822.0m and on the basis of interpretation of borehole core logs, the dam block no. 1 was lowered up to EL 795.0m (instead of EL 825.0m) and block no. 2 rested at EL 785.0m (instead of 798.0m).

Subsequently, during further progress of excavation on left bank of dam being done concurrent to drilling of above mentioned additional four holes, a shear zone (55⁰-60⁰ / N070⁰ to 090⁰, affected zone varies from 3.5m to 5.6m, Clay gauge >20cm, with crushed/fractured rock mass) encountered askew to the river flowing direction passing from u/s to d/s (heal to toe of the dam).

The Shear zone was encountered in all these additional four drill holes at different depth with variable thickness.

5. Investigations, delineation and interpretation of the Shear Zone

With the progressive excavation, when the excavation in block no. 6 & part of block nos. 5 & 7 excavation (EL ~765.50m) was in progress the major shear/weak zone was encountered in all these blocks.

Sub-surface investigation was done  through those additional four boreholes, mentioned earlier above (DH-13 to DH-16), with total depth of 187.0m, drilled  on the dam site (dam foundation blocks 4, 5, 6 and block joint of 5 & 6), to ascertain the thickness, depth and behaviour of the shear zone. Frequent change in attitude of shear zone, was observed. 

Shear zone with varying thickness of clay gouge material and affected zone  (approximately 3.5m to 6.5m) was encountered in the main dam pit area in the block no. 8 (at EL ~755.0m: near toe of dam body) and in the inclined foundation of the dam block no. 7 (below EL 765.0m) and below dam block nos. 5 & 6.

The encountered rock mass, in the drill holes, comprises predominantly quartzo-feldspathic-biotite-gneiss (QFBG), biotite gneiss, leucogranite with bands of biotite schist of variable thickness. At places the rock mass is intruded by thin veins/patches of pegmatite. Shear material mainly comprises highly pulverized rock mass, granular rock flour, fractured rock mass, clay gouge with slush, and broken rock fragments.

The drill core logging revealed that the shear zone depth varies from 3.1m to 11.22m and affected/fractured rock mass zone below the shear zone varies from 6.0m to 20.0m in depth.

The shear zone is traversing from dam heal (block no. 5), dam centre (block no.6) to dam toe (block no. 7) having curvilinear nature, however, it is encroaching in block no. 4 by ±1.0m near RD 73.0m in a limited area; between CH ±18.69m and CH ±20.0m at EL 765.0m and in block no. 8 d/s portion it is intersecting between CH 97.0m and CH.102m at El 755.0m. The general trend of shear is 35⁰-42⁰/N 070⁰ to 080⁰.

 However, there is variation in the shear’s attitude due to warping of foliation and its curvilinear nature. In the block no. 5 the thickness of shear zone (including fracture zones and affected zones) at the dam axis is 13.97m whereas, in the u/s part of the dam (near CH ±20.0m) it is 14.19m thick. Sheared material comprises moist clay gouge (0.5m to 1.0m thick), rock flour, crushed/fractured rock, fragmented rock pieces and intermittently hard patches of parent rock (no strain zones). The affected zone varies from 4.0m to 30.0m.

The foundation surface in the mapped area is undulatory due to intersection of different joint sets and formation of wedges. The geological mapping revealed that the mega shear zone is bounded by two shear zones (SZ-1, forming left side boundary, having clay gouge thickness 5cm -20cm and SZ-2, forming right side boundary, having clay gouge thickness 8cm – 100cm) passing through block nos. 5, 6 and 7 from upstream to downstream direction, dipping into left abutment side, and having variable thickness.

Infilling material of this weak zone comprises crushed rock mixed with minor clay and at places small lenses/chunk of QFG. The width of this zone varies from ±7m, at u/s side near dam axis, to ±2m at d/s side. The attitude of its two boundaries i.e. SZ-1 (20⁰-55⁰/N070⁰-100⁰) and SZ-2 (20⁰-55⁰/N050⁰-110⁰ also vary from u/s direction to d/s direction at different places. Besides, major shear there are 13 nos. shear seams were recorded during foundation grade mapping.

Photographs of Shear Zone

6. Treatment of the Shear zone

Finally, a 125.0m long, 5.0-35.0m wide and 13.0-15.0m deep shear trench was made in order to treat the shear. The field observation suggests that this shear is a discrete fracture between blocks of rock containing several parallel or anatomizing(i.e. branching and reconnecting) shears particularly at the toe of dam body near dam block nos. 7 & 8 and may have formed in brittle ductile regime.

Photographs of Shear zone trench excavation

* The Shear Zone though has been replaced in its depth of 13m by RCC Plug, its performance with time would need to be watched.

The consultants had failed to detect  and delineate  the Mega Shear Zone in the  Geological Investigations which formed the basis of selection of the respective Dam Sites,  in both the cases of Punatsangchhu-I and Punatsangchhu-II HE Projects.  In the case of Punatsangchhu-I a major slide of right bank on the shear zone  has halted the dam construction by 7 years as of present. In the case of Punatsangchhu – II, the detection, delineation and treatment of the shear zone delayed the dam construction by more than a year. The treatment and strengthening of shear zone in both cases has made huge time and cost over run in the Projects.

The excavation of the Shear Zone involved excavation of 43 million cubic metres in sheared rock/ fractured rock mass. The Shear Zone trench was refilled by M25 grade and M20 grade of cement concrete provided with 2200 MT of 32mm dia. steel reinforcement . The consolidation grouting done through combination of Multi Stage and Single Stage grouting in the shear zone area, as per my information, consumed 8 bags of cement per hole, thus aggregating to total consumption of 9297 number of cement bags. The grout acceptance experience in the affected area after excavation of the Shear Trench gives an indication of the clay content in the fractured rock material present under the shear zone. The Shear Zone treatment has costed Rs. 387 million and more than a years delay to the Project.

The Shear Zone was missed by the Consultants in the drill holes no. DH5, DH9, DH10 , DH 12 and DH22 which were done in the Dam Block no. 5 at DPR stage and later in initial construction stage, despite their location being almost the same as that of additional four holes DH13, DH14, DH15 & DH16 in which the Shear Zone was intercepted at the end during excavation at the behest of Project Geologist and Project Engineering and Construction Agency team.

The massive Shear Zone had been finally detected and treated.

* However, the debatable point is that if the presence of this massive Shear Zone of that great a size , which affected foundations of four numbers of dam blocks from heel to toe, in a maximum width of 30m and depth more than 13m , had been detected at DPR stage, then, should this very site been preferred as dam site ?

* In case the answer is NO, then whether construction of the dam here at this site is a compromise of a sort ?

The detailed paper co-authored by me “Delineation and treatment of Mega shear zone in the main dam foundation : A case study of Punatsangchhu HEP-II, Bhutan” was selected for 26th ICOLD Congress” held in July on 1-7-2018 at Vienna, Austria.  The Paper was also selected for oral presentation. 

( Second of the incidences of a chain of massive surprises in the two Punatsangchhu Projects in Bhutan )

Lok Sabha TV conducted a panel discussion on the study on Water Management of the Indus River System and its Implications for India’s Foreign Policy. The invited panelists were Prof. Manohar Khushalani, Sushant Sari  and Akshay Singh.

Manohar Khushalani started the discussion by describing the Indus Water Treaty.

The Indus Waters Treaty is a water-distribution treaty between India and Pakistan, brokered by the World Bank, to use the water available in the Indus System of rivers. It was signed on 19 September 1960 by Jawaharlal Nehru, the then Prime Minister of India, and Ayub Khan, the President of Pakistan.

• Eastern Rivers
  • Sutlej
  • Beas
  • Ravi

• Western Rivers
  • Jhelum
  • Chenab
  • Indus

The Treaty gives control over the waters of the three eastern rivers — the Beas, Ravi and Sutlej with a mean annual flow of 33 million acre-feet (MAF) — to India, while control over the waters of the three western rivers — the Indus, Chenab and Jhelum with a mean annual flow of 80 MAF — to Pakistan. According to treaty, all the water of eastern rivers shall be available for unrestricted use in India. India should let unrestricted flow of water from western rivers to Pakistan. This does not mean that India cannot use the western river’s water. They are allowed to use it for limited irrigation and non-consumptive needs such as for generating electricity. This means that the treaty has allocated Pakistan 80 percent of the water from the six-river Indus water system. China has been kept out of the treaty even though Indus originates from Tibet because the topography of the Indus Water System does not allow China to change or stop the flow of the water. Neither of the countries can unilaterally walk out of the pact.

Indus Water Treaty is considered to be one of the most successful water-sharing endeavours in the world today. For 56 years, both India and Pakistan have been peacefully sharing the water of Indus and its tributaries, thanks to The Indus Water Treaty (IWT). But since the ratification, there have been a number of issues raised by both countries over the ethical use of the treaty and the water itself.

India has always treated the security issues and water issues as 2 different subjects.

The discussion also gave insights into the disputes and objections raised over this treaty.

The most frequently raised issue by Pakistan is that India can stop the water flow to Pakistan. Can India stop the water flow to Pakistan? No. Not as per the treaty. India can only utilize the provisions of the treaty to reduce the water flow by a small number but cannot completely stop the flow. India has in fact built many hydro power projects to which Pakistan has objected repeatedly. Even if India decides to reduce the water flow by a large amount, they do not have enough infrastructure to use the additional water and it may even create floods in Kashmir. The decision of not giving water to Pakistan may further enrage the terror elements in the country, making them intensify their attacks on India. This decision can also affect India’s relations with other countries like Nepal and Bangladesh with whom they have water treaties as well. 

Most of the issues have been resolved with legal procedures and mutual understanding from both sides. Though after the 2016 Uri attacks, India threatened to revoke the Indus Water Treaty but so far the threats have not been materialised.

BTP Student: Sejal Kumar, Aysha Fazilath, Vyshakh Dharan, Rahul Patwardhan

PUNATSANGCHHU-I DAM – RIGHT BANK FAILURE

You can listen to the Presentation and discussion on the failure of right bank at Punatsangchhu-I dam site, held on DDAG Open House, given at link : https://lnkd.in/dPGjpJk

( First of the incidences of a chain of massive surprises in the two Punatsangchhu Projects in Bhutan )

–  Huge Setbacks Due To Failed Assessments Of Geology & Rock Supports

There is a strange coincidence of huge rock mass failures, which  happened in the two mega hydroelectric projects named Punatsangchhu -I & II H E Projects, under construction since 2009 -10 in Bhutan.

            The Punatsangchhu-I Hydro Electric Project (PHEP-I)  a 1200 MW project with   scheduled commissioning date of year 2016 and at sanctioned cost of Rs. 35146 millions  and  new approved Cost of Rs. 94000 millions (US$ 1.34 billions), is expected to have further escalating its cost possibly to Rs. 121000 millions (US$ 1.74 billion). The Head race tunnel and Desilting Arrangement lying completed since 2015, Powerhouse complex 98% ready have an already incurred cost of about Rs. 80000 millions .

However, even the start of concreting for construction of 136m high dam is a big uncertainty after its Right Bank suffered a massive slide with continued movement of the big hill mass about 500m height towards valley and downstream by 5m and vertically subsiding by 5m in a week in July 2013.The hill mass movement has continued at slower pace for more than year, sliding on SZ-2 Shear Zone.

            A whopping cost of about Rs. 30000 millions, out of above cost, may get attributed to extra works necessitated because of ” geological surprises”.

            The Punatsangchhu-II  (PHEP-II),  a 1020 MW project with scheduled date of commissioning of year 2017 at sanctioned cost of Rs. 37778 millions and  a new approved project cost of Rs. 72900 millions ( US $ 1.04 billions), possibly to be further escalating to Rs. 80000 millions ( US $ 1.14 billions), with already incurred cost of about Rs. 65880 millions is delayed due to the huge rock mass failure in its underground Downstream Surge Gallery (DSSG), resulting in a huge cavity of about 91m height x 70m length and 45m width in the crown of the DSSG. The Dam foundations had  encountered, a thus far unexplored, mega shear of maximum 30m width, cutting across the length all the 4 dam blocks diagonally. The shear zone with its about 35ᵒ to 45ᵒ dip, continued under the foundations to large depths.

            Again a  whopping cost of about Rs. 15000 millions, out of the above cost,  may get attributed to extra works necessitated because of ” geological surprises”.

            Occurrence of too many geological surprises, which were blamed for the big mishaps in the two mega Projects, intrigues one to investigate if ‘ harping on the geological surprises‘ may only be a scapegoat for the lack of proper geological investigations done by the Consultants and inappropriate design of rock support measures done by the Designers, who were the same for both the Projects .

The Case of Punatsangchhu-I H.E Project Dam Right Bank Failure :

1. Selection Of The Dam Site  Without Detailed Geological Investigations

( the first miss)

The present dam site was selected in 2009  at a new site, located 1.5km upstream of the original site which was considered in the Detailed Project Report (DPR). The shifting of location to the new site was done  just before taking up the Tender activities  of the Project. The selection of this new site was done on the basis of some geological explorations done at different times earlier, apparently with a purpose of studying geological conditions of the reservoir rim. The Tender  Drawings of Geological Details, issued in 2009 , showed the geological conditions that were based on the limited exploration done till that far. The Tender stage geological drawings  at the dam axis and  at various sections upstream and downstream indicated no Shear Zone to be encountered. The tender stage Geological Sections at Dam axis  and at 100m downstream are placed at Fig -1 and Fig.- 2 below.

• Tender Stage  Geological Drawings of 2009  Show no Shear Zone in Right Bank :

Tender Drawing of Geological Section At Dam Axis Fig.- 1	Tender Drawing of Geological Section At 100m D/S of Dam Axis Fig.- 2

2. Geological Assessment done By The Consultants in 2011 , At Design & Construction Stage  Did Not Detect  The Presence Of The Massive Shear Zone And Delineate  Continuity Of The Shear Zone In to Hill At Vulnerable Dip :

( the second miss)

The Geological Investigation at the present Dam site was carried out during 2010 – 11 by the Consultants after issue of Tender Specification Drawings for deciding the stripping limits and designing the rock support system for excavation of the dam pit. The excavation for the 136m high dam foundations involved excavation of a depth of 300m.

            Earlier Consultants had shown lacksidal attitude when they did not carry out detailed Geological Explorations for Selection of Dam site in 2009. This was followed, apparently, yet by a limited explorations done in 2010-11 to decide the stripping limit and design the excavation support details of the right bank  slope of 300m excavated depth.

• Did The Construction Stage  Geological Drawings of 2011  Missed To Connect Intercepts of Sheared Rock Mass In Drill Holes And Delineate The Steep Show Shear Zone in Right Bank ??

The  sheared rock mass intercepts were recorded in the Drill Holes DH25, DH31 located at dam axis and DH26  located at 20m D/S of Dam axis and in drill holes at further downstream in the geological investigations carried out by the Consultants during construction stage for excavation support designs .

• Apparently the Consultants had failed to connect these intercepts of sheared material found in different drill holes to establish the extent and the vulnerable dip the major shear zone would have, though they had detected presence of  the sheared rock material in these explorations.

Logically, after the sheared material was intercepted in different drill holes, it should have been investigated whether the intercepts were a part of one single Shear Zone. More exploratory drill holes may have been done further up the hill to connect the intercepted sheared material incidences and delineate the attitude of the Shear Zone, of which these intercepted shear material could be possibly a part of. Thus the inaccurate  geological assessment was made by missing to interpret and detect continuity and rising dip angle of the major Shear Zone in right bank of PHEP-I  dam site.

• The required further geological investigation does appear to have been missed by Consultants despite that the Resident Geologist of Project Authority had provided the Consultants the following detailed geological note which clearly mentioned presence of shear zones and brought out the possibilities of slides happening on the shear zone.

3. Geological Assessment by the Project’s Senior Resident Geologist, at     Construction Stage in 2011, Reported Presence of the 1.5m Thick Shear Zone , Prone To Sliding And Its Need for Proper Strengthening Which Was Neglected By The Consultants :

( the third Miss )

The Geological Report of 2011 of the Sr. Resident Geologist of the Project is reproduced below :

“The strata shows small scale, S- shape tight folds and broad warping of the beds at places, indicating that the rock strata has undergone the polyphase deformation in the past leading to development of numerous criss-cross structural discontinuities like joints, shears etc. of different orders. Five prominent and two random joint sets are recorded in the right bank. The foliation is very close to moderately spaced from 2cm to 60 cm and dips towards valley slightly in d/s direction; however rolling of dip is observed at places, there it dips into the hill due to folding and warping. The general topography and gentle natural slopes on the right bank of river are controlled by low and valley ward dipping foliation planes.

            The drilling data on right abutment has indicated the presence of numerous thick deformed/sheared zones/schistose rock mass having very poor RQD (below 30%) and nil to poor core recovery (below 40%) at different depths. Such rock mass is fissile and fractured, which breaks along foliation and other prominent joints and has very low strength. One deformed zone/band (1m thick) along foliation is delineated at Ch. 13m d/s of dam axis at El. 1220m and at Ch. 23m d/s of dam axis at El 1205m and dips at 150-250 in the downstream.

A ± 15m thick band of fractured, biotite rich gneiss with schistose partings and sheared seams, which dips gently towards valley along foliation was delineated during drilling and is expected to expose in all along the foundation of dam block nos. 7, 8, 9,10 &11, and below the foundation of block nos. 12 and 13. The core recovery and RQD in this rock mass are very poor. Such bands striking parallel to the flow and dipping towards valley may form passage for water and are prone to slide under forces, hence require proper treatment during excavation.

Another shear zone (± 1.5m thick), which was encountered in the drift strikes from d/s to u/s and dips gently into the hill slightly towards upstream. This shear zone is expected to expose in the foundation of dam block no.11 at El ±1165m and below the block no. 12 along its dip & in the reservoir along its strike in the upstream. Such shear zone also needs proper treatment and strengthening as they form the avenues for water draining from reservoir and development of the hydrostatic pressure.

            Layered/stratified/foliated rocks with softer beds (schistose partings/shear zones) confined between harder beds are always prone to shear stress problems/sliding, which inevitably develops in the rock in conjunction with pressure/load.“

• Geotechnical Problems Identified in the 2011 report of the Resident Geologist :

• Layered/stratified/foliated strata with soft bands confined between hard rocks.
• Occurrence of folds and warping indicating the signs of deformation and presence of  local stress areas.
• Presence of thick shear/fracture zones and biotite rich bands of gneiss/schist having very low strength and less RQD.
• Moderately jointed and very blocky nature of the rock mass with steep joints having longer continuity and persistence, striking along the flow direction.
• Valley wards dipping foliation and prominent open joints.
• Formation of wedges due to intersection of the prominent joints.
• Presence of the parallel discontinuities with variable zones of permeability. Moderate to high lugeon values indicating the fracture permeability and fissured rock mass.
• Low to moderate strength of rock mass.

The above report shows that there was adequate warning given in the 2011 geological report by the Resident Sr. Geologist of the Project Authority of a 15m thick fractured rock mass present all along the foundations of dam blocks 7,8,9,10,11 and 12, with shear seems and dipping in to the valley, having potential of sliding . The report also informed of the 1.5m thick Shear Zone dipping in to the hill which would be getting exposed in excavation of dam blocks 11 and 12 . The report further warned that the layered/stratified/foliated rocks with softer beds (schistose partings/shear zones) confined between harder beds are always prone to shear stress problems/sliding.

• The report specifically asked to provide adequate support and treatment which apparently was not so designed.

The Rock Support Measures comprising only 150mm shotcrete and 32mmDia. 7.5m Long rock anchors , would have been designed in 2010 -11 based on the limited information gathered by the  Designer / Consultant and not inferring and analyzing the sheared rock mass occurrences as a Shear Zone. Probably the Cable Anchors may have been found required to be provided , if analysis of the excavated slope would have been done incorporating the Shear Zone. However, there were no cable anchors designed for the Right bank excavation support, while provisions of cable anchors were done in Left bank excavation profile. Therefore, the rock anchors and shotcrete would have not been designed to hold the excavated profile of the Right abutment against a potential slide on the shear plane, as no such Shear Zone had been identified by the Consultants till that time. The designed provisions thus must have been under provisioned to safeguard a 300m deep excavated slope against the later resulted Massive Failure of  Right Bank  during its excavation in July 2013.

4. The Excavation Stages From 2010 To July 2013

5. Incidental Identification of the Presence of the Shear Zone :

• Considering the weak rock mass condition, a 5.5m x 5.5m wide and 60m long gallery/tunnel with 15m long x-cuts in upstream and downstream side was excavated in right abutment (Dam Block-13) at invert El 1169m, in 2011 to February 2012, for consolidation grouting.

• Until July 2013, the excavated Right Bank Profile stood intact with provided support comprising 32mm Dia. 7.5m long Rock Anchors and 150mm Shotcrete.

It was on around 10 July 2013 , subsequent to a Shear Zone getting exposed, that a few cracks were observed on the road surface which goes winding up on the Right Side Hill of the dam site, leading to the Project colony. Also the steel rib supports provided in the Grouting Gallery, at El. 1169m in the Right Abutment, were seen to be twisted and the invert floor of the Gallery was seen to have settled and developed cracks.

Immediately a team of the Consultants and the resident geologists of the Project visited the Grouting Gallery and prepared the following Geological Note based on their field observations :

6. Geological Assessment Note given   by the Consultants on 12th July 2013 after observing cracks & Settlements in the Grouting Gallery in Right bank , Reported presence of Shear Zone Affecting 1.5m ~6.5m Thickness & dipping 25⁰-45⁰/N010-040 :

The Geological assessment Report of 12 July 2013 is reproduced below :

“ The entire excavated reaches of the grouting gallery and x-cuts have been supported with steel ribs (200 x 100mm) @ 1m spacing. The final lining and grouting through the gallery is yet to be done. Recently some settlement/deformation is noticed in the gallery and x-cuts. Hence a joint inspection visit was made to the site on 12th July, 2013 for geotechnical assessment and remedial measures. The rock mass exposed in grouting gallery and x-cuts is jointed, very blocky and weathered quartz-biotite gneiss with thin schist bands and shear zones. The rocks are deformed in the form of folding and warpings and distressed in the form of open/wide/stress relief joints.

The rock mass encountered falls inpoor to very poor grade category (Rock class IV and V). One major shear/deformed zone (Clay gouge 30-200cm, affected zone 1.5 to 6.5m) dipping 25⁰-45⁰/N010-040 cuts across the gallery from RD 27m (left wall) to RD 48m (Right wall) and over the crown beyond RD 50m. Shearing effect is more beyond RD 34m as it forms hinge portion of the fold. This shear/deformed zone strikes from d/s of dam (closer to valley) to u/s of dam (Farther to valley) and as per projections it was expected to cut in u/s x-cut between RD 15m (Crown) to RD 35 (left wall) with less horizontal cover on right wall.

• The location and pattern of the settlement/deformation occurred corresponds to the disposition of the major shear zone in the gallery and x-cuts and mobilisation of its broken zone under pressure. The shear zone is low to moderate dipping and runs oblique to the main gallery from left to right wall along strike.
• Such settlements are time dependant deformations in weak/soft rocks occurred after completion of the excavation and installation of the primary support depending upon the load/pressure; stand up time of the rock mass and support provided.
• Once commenced, such deformations tend to increase with the time if structure is not provided with the strong support.”

The Consultants noticed presence of the major Shear Zone, for the first time, in July 2013 only during inspection of the Grouting Gallery. Where as, the Sr. Resident Geologist of the Project Authority had already informed of the 1.5m thick Shear Zone dipping in to the hill which would be getting exposed in excavation of dam blocks 11 and 12, in his note provided to the Consultants in 2011 . This Shear Zone had did get exposed, in July 2013, at El. 1110m in excavation of dam block no.12.

7. Massive Slide of 500m high x 300m long Hill Mass in Right Bank on 24 July 2013 :

Soon after the settlement/deformation was noticed in the gallery and x-cuts in the Right Bank, a massive slide in the Right Bank occurred which detached a hill mass in Right bank of a reach 500m in height , 300m in length and moved it over 5m towards the valley and 2m along the flow with 5m vertical subsidence. Cracks of about 10m to 15m depth appeared on the road and hill slope.

           

The right bank failure resulted in huge hill mass slide, causing separation of hill mass of about 500m ( 1/2 km) height , 300m length and 40-50m in its thickness under the ground surface. The slide created about 10m deep fissures at the top levels of slip in this stretch of the hill mass. This reach of the hill suffered   subsidence/ settlement of  the hill by 5m vertically and moved en-mass towards the river side by 5m and along river in downstream direction by 2.5m.  

The photographs below show the sagged Cable Car rope due to subsidence of foundations of their end anchors provided at a bench at El. 1250m in the Right Bank

8. Delineation of the Shear Zone in the Right Bank

The hill mass stretch of over 500m height in a 300m length kept moving at faster pace for four days period, resulting in a shift of the separated big hill mass over 5m in to valley and over 2.5m along the direction of flow of river with a subsidence of the hill mass of 5m. The movement of this hill mass continued at smaller pace for days , weeks and months to follow. The hill mass seemed to have had slid over the Shear Zone. However the extent of the Shear Zone extending in side the hill was not known at that time. The cracks and fissures of about 10m depth had surfaced at locations as far till about 500m height of the hill.

The outer boundary of the hill surface affected by the massive slide was marked. A total 23 numbers of drill holes , running a total depth of 3500m were driven along the boundary of the slide affected area. The Shear Zone was delineated from the core logs .

Comparison of Geological Assessments Done By The Consultants In 2011 Investigations V/s Actual Geological Conditions Encountered & Established in 2014 After The Massive Slide :

The Sheared Rock Mass Intercepts Were Not Inferred, By The Consultants In 2011, To Be A Shear Zone Continuing In To The Hill Fig. – 11	The Shear Zone SZ2, Delineated As Dipping Sharply & Deeper In To The hill Was established Through Additional Holes In 2014 , Only After 2013 Slide Fig. – 12

9. Synopsis of the Geological Investigations Done in 2009, 2011, 2013 and 2014 :

• The Consultants had failed to detect  and delineate  the shear zone in the  geological investigations forming the basis of selection of the present dam site in  2009.
• The Resident Geologist reported in his Note in 2011, the  presence of a shear zone SZ-2 assessed by him from the geological explorations done in 2011 for detailed design of slope excavation supports. But the Consultants / Designers  had  failed to build on gathered information and thus ignored to do further exploration to  identify and delineate the continuity of the major Shear zone which extended in to the hill at a vulnerable dip angle.
• The Resident Geologist had reported, in his Note in 2011,  of potential risk of slide along the Shear Zone and suggested proper strengthening. The Consultants apparently failed to do a slope stability analysis for the potential destabilised  condition of the excavated slope in the Right bank arising from presence of the  steeply dipping major shear zone, despite its warning given by the Project Authority.
• Therefore, the Consultants failed to design the appropriate support measures required to be provided during progress of excavation of the Right Bank, to ensure stability of the Hill Mass against hazard of a potential  slide of the big hill mass , which eventually slid  en-mass in its 1000m height, 300m length and about 30-40m depth inside the hill.  
• Incidentally the Cable Anchors were provided at various levels in the Left bank excavated slopes, but the Consultants failed to establish the need of design and provision of Cable Anchors in the Right Bank to hold the endangered  hill mass, which eventually  separated out in the Right Bank and slipped over the Shear Zone.
• After the slide, a total of 3500m of length in 23 numbers of drill holes were done in 2014, along the boundary of the affected hill mass , which delineated the alignment of the shear zone.
• A more intelligent inference from the Sheared material intercepts in the drill holes done in 2011, would have established the need of a few more drill holes and detected continuity of the shear zone SZ-2 with its  dip  risingng sharply in to the Hill.

It may be seen that firstly there was lack of Geological Information gathered for selection of the present dam site. Thereafter, the inaccurate  Geological Assessment was made by Consultants from the explorations that were carried out at the Construction stage for Designs  of stripping limits of the excavation and Support Designs in 2011. Missing to connect the sheared material intercepts in detection of the Shear Zone had resulted in under provisioned design of the rock supports. The designed 32mm dia. rock anchors of 7.5m length were no match to and too insufficient than the required measures e.g. longer cable anchors like those provided in the Left bank . Thus the inappropriate and inadequate rock supports led to the major hill mass slide in the right abutment of PHEP-I dam, during its excavation in July 2013.

The slid hill mass has been in motion for years thereafter, though at much slower pace, despite a number of measures designed by the Consultants and implemented in the field to stall the movement of the hill . A number of more slides have happened in the downstream of the main slide, after 2013 till recently in 2018.

10. Strengthening Measures Implemented In Right Bank After Slide :

• After the slide, the Consultants designed  installation of about 1050 numbers of  300mm dia steel encased micro piles from 11 different levels   as a strengthening measure for the destabilised hill mass.
• Further also subsequent to the hill mass slide, bout 250 numbers of 2m diameter steel reinforced RCC piles of depth varying from 50m to 85m  were driven from various levels along the excavated slopes. Each of these RCC piles were socketted in to sound rock for 10m length beyond the Shear Zone.
•  About 50,000 MT of cement was consumed in grouting the slipped hill mass, carried out  through 566 numbers of drill holes, totalling together to 123 kilometres of depth, to improve the deteriorated quality of the disturbed hill mass in local vicinity of dam axis after the slide as a strengthening measure.
• Also 1000 numbers of 100 MT capacity Cable Anchors from 12 different levels were installed.

• Important Observation :

          It was experienced that during many instances of drilling, undertaken for installation of micro piles, the drill rod/ shaft used to drop for one to two meters depth, by itself without requiring any drilling effort, thereby indicating that the entire hill mass in the Right bank has been rendered geologically further weak & poor and porous resulting from the massive movement of the hill mass.

11. Present Status in June 2020 :

• The right abutment hill continued to move for years after implementation of all of the above mentioned strengthening measures , but at reduced pace. The 2m dia piles too may have suffered some deflection.
• Norwegian Geotechnical Institute (NGI)  has advised for off loading the right abutment by excavating and removing a huge part of overburden from the right abutment, starting from much higher levels, to improve its stability against sliding.

• A proverbial “stitch in time” in 2011 by adopting an adequate investigation, appropriate analysis and design by the Consultants may have saved  from occurrence of massive rock failure in the Right abutment.

• The actual construction of the dam having halted since 2013, despite various strengthening and rehabilitation works being attempted to rescue the situation, there have been two more slides in the Right Bank in the immediate downstream of location of the massive slide of 2013 .

• However, after 7 years of the massive slide which happened in July 2013, even the start of concreting for construction of 136m high dam is a big uncertainty as of now in 2020. With about Rs. 80000 millions spent already, the future of the Project apparently hangs in uncertainty as of now.

There remains a point of debate that with given geological conditions in the Right bank, whether this site was a fit site for implementing excavation of 300m depth ??

Moreover, the “churning” of the rock mass with in the hill, affected by the massive rock mass movement, which pushed the hill to over 5m, possibly would have created many voids in the rock mass. It can be adjudged so from what was indicated by many an incidents of self dropping by a meter or so, of drilling rig shaft, experienced while driving 325mm piles in the slid mass. Therefore, it may also be debatable that whether this Right Bank be making a safe and a water tight abutment for a 136m high dam??

Manohar Khushalani was one of the panelists who appeared live on NDTV for a panel discussion on the water crisis faced in India. This video gives an insight into the problems faced by Indians when it comes to water as well as some expert opinions on this matter. Some of the other panelists are Raghav Chadha, VK Madhavan, Medha Patkar, Dr. Vaman Acharya, and Arunabha Ghosh.

India is facing a major water crisis. People are facing drought-like situations and running out of tap water in major cities like Bengaluru, Chennai and even in the capital, Delhi.

Raghav Chadha started the discussion by giving facts such as, the water availability has increased in Delhi in the last 4 years from 50 percent of the population receiving usable water to 80 percent. He also said the government is planning to rejuvenate lakes and also create new lakes as resources for freshwater. He also mentioned that the condition of south delhi districts, which earlier faced the problem of clean water and also improper sewage treatment, has now been fixed and will be provided with usable fresh water in the upcoming months.

Prof. Manohar Khushalani mentioned the fact that India as a country consumes more groundwater than any other country. He also stated that water should now be treated as a subject for the central government instead of being treated as a state subject. The states do not have enough coordination and are busy in handling the inter-state water disputes while the residents are still suffering. He also mentioned the fact that there needs to be more research put into methods for getting water from rivers and other sources.

VK Madhavan then gave some key perspectives such as, that the water crisis is caused not only due to excessive use of water but also improper distribution and conservation of water. He argued that the source of tankers that provide water to communities is uncertain, and there are still major areas that don’t have assured access. At a later stage of the discussion he also mentioned that cities are largely dependent on groundwater but do nothing when it comes to implementation methods like drip irrigation to conserve water. India receives a huge amount of rainfall which doesn’t necessarily seep into the ground and thus should be stored and filtered in an efficient manner.

Medha Patkar emphasised on the fact that the current structures and working of dams and related buildings are destroying the rivers. She also highlighted that the government should be focusing more on mini and micro water shedding instead of macro water shedding. She also said that the government’s main strategy should revolve around controlling the access to water on a per house basis and that for major changes the community itself should play a big role.

While water scarcity in India as an issue has not been discussed as topmost important matter, it is high time the people should focus on this subject, or else it’ll be too late to realise and it will affect India and its people way more than it is doing today.

Chennai, the fourth largest city in India, is the worst hit city when it comes to water crisis. Chennai city officials declared that the day when almost no water is left, had been reached, as all the four main reservoirs supplying water to the city had run dry. Two years of deficient monsoon rainfall, with a rainfall deficit of 55 percent, particularly in late 2017 and throughout much of 2018 had led to this crisis. This has impacted millions of people who are left with inconsistent access to water. This is said to be the case of current developed states like Karnataka and Maharashtra in the future. Karnataka has very small amounts of resources left and soon will be piling their hopes on Maharashtra to receive water. On the other hand, Maharashtra because of its size and location, is under immense pressure to provide not only to its residents but also neighbouring states. The rainfall in these 2 states has also started declining in the past few years which only has caused more problems.

Some of the other valuable points that are mentioned by the panellists are; controlling the use of water in the agriculture industry. Sugarcane, which is a crop that depends on water heavily, is grown in parts of the country that have a scarcity of supply. This reduces the availability of water for the people for their personal use; recycling and recharging should be the topmost priority of any water management organisation, i.e. filtering out the water received by rain and distributing that water to the households that don’t have access to groundwater; the yearly monsoon pattern shows that the rain is declining in most parts of India and this also should be a major concern; even though the government is planning on making new residential buildings for development, they are not checked about proper water consumption levels and are sometimes specified with uncertain sources of water so as to receive license to build those structures.

CHAIN OF MASSIVE SURPRISES IN TWO PUNATSANGCHHU PROJECTS

–  Huge Setbacks Due To Failed Assessments Of Geology & Rock Supports  

            There is a strange coincidence of massive geological surprises and huge rock mass failures, which  happened in the two mega hydroelectric projects named Punatsangchhu -I & II H E Projects, under construction since 2009 -10 in Bhutan.

            The Punatsangchhu-I Hydro Electric Project (PHEP-I)  a 1200 MW project with   scheduled commissioning date of year 2016  at  cost of Rs. 35146 millions,  new approved Cost of Rs. 94000 millions (US$ 1.34 billions), expects further escalation in its cost possibly to Rs. 121000 millions (US$ 1.74 billion). The Head race tunnel and Desilting Arrangement lying completed since 2015, Powerhouse complex 98% ready have an already incurred cost of about Rs. 80000 millions . However, even the start of concreting for construction of 136m high dam is a big uncertainty after its Right Bank suffered a massive slide with continued movement of the big hill mass about 1000m height towards valley and downstream by 5m and vertically subsiding by 5m in a week in July 2013.The hill mass movement has continued at slower pace for more than year, sliding on SZ-2 Shear Zone.

            The Punatsangchhu-II  (PHEP-II), a 1020 MW project with scheduled date of commissioning of year 2017 at cost of Rs. 37778 millions, new approved project cost of Rs. 72900 millions ( US $ 1.04 billions), expects further escalationin its cost to Rs. 80000 millions    ( US $ 1.14 billions), with already incurred cost of about Rs. 65880 millions, is delayed due to the huge rock mass failure in its underground Downstream Surge Gallery (DSSG), resulting in a huge cavity of about 91m height x 70m length and 45m width in the crown of the DSSG. The Dam foundations had  encountered, a thus far unexplored, mega shear of maximum 30m width, cutting across the length all the 4 dam blocks diagonally. The shear zone with its about 35ᵒ to 45ᵒ dip, continued under the foundations to large depths.

            Occurrence of too many geological surprises, the apparent cause of the big mishaps in the two mega Projects, intrigues one to investigate if ‘ harping on the geological surprises‘ was only a scapegoat for the lack of proper geological investigations and inappropriate design done by the Consultants.

1. PHEP-I  Dam Right Bank Failure :

Shear Plane Continuity in to the hill was NOT detected by Consultants from Geological Investigations done in 2011 and therefore not provided for in Design of rock support for excavated slope	SZ-2 Shear Zone,  the cause of the huge hill mass slide,  delineated to be  dipping sharply in to the hill was established through additional drill holes done in 2014, but only after the slide in 2013.

2. Mega Shear Encountered In PHEP-II Dam Foundations

Geological X-Section At Dam Axis (DPR Stage) Shows No Shear  Zone in the Dam Foundations	Geological X-Sections Depicting Shear Zone at Dam Axis, Ch. 40m,60m and 80m D/S of Dam Axis

Shear Zone Traverses From Heal in Block 5 to Toe in Block 8 with Trend 35ᵒ-45ᵒ/N070 -080 With Affected Zone 4m to 30m Wide

3. Huge Rock Mass Failure In DSSG of PHEP-II :

Geological X- Section of DSSG Assessed By Consultants Showed No Shear Zone

The massive rock fall in the Downstream Surge Gallery Cavern happened on 03 March 2016 during the progress of benching excavation in the cavern. The cavern had been excavated to its 2/3 rd depth and the crown stood intact for three years before the rock fall. Six technicians of those working in the cavern at the time of collapse got buried alive under the falling muck and died.

• The individual case studies of  the Rock Mass Failure in Punatsangchhu-I Dam ; Encounter of Un-Explored Mega Shear zone in Punatsangchhu-II Dam;  and The Huge Rock Mass Failure in DSSG of Punatsangchhu-II HE Project,  dealt in details, shall  be posted separately soon please.

Since you’ve seen part of the debate in this video, you would also appreciate that there was not enough time to go into this exciting topic in detail. My intention is to expand my point of view in a series of articles beginning with this one – Part I of the series. Also in Part II we will share the complete debate, so that we can get our co participants viewpoints across as well. To begin with, lets look at the sequence of events as reported by BBC ^​*​

The US Department of Defense has released three declassified videos of what it now calls an “Unexplained Aerial Phenomena” – the new nomenclature for UFOs

The Pentagon said it wanted to “clear up any misconceptions by the public on whether or not the footage that has been circulating was real”.

In its statement, the Pentagon said: “After a thorough review, the department has determined that the authorised release of these unclassified videos does not reveal any sensitive capabilities or systems, and does not impinge on any subsequent investigations of military air space incursions by Unidentified Aerial Phenomena.

“DOD [Department of Defense] is releasing the videos in order to clear up any misconceptions by the public on whether or not the footage that has been circulating was real, or whether or not there is more to the videos. The aerial phenomena observed in the videos remain characterized as ‘unidentified’.”

The videos had already been leaked in 2007 and 2017.

Two were published by the New York Times^​†​, while the third was leaked by an organisation, To the Stars Academy of Arts and Sciences, co-founded by former vocalist Tom DeLonge. The musician co-founded the academy in 2017 in order to study UFOs and other paranormal phenomena.

Tweeting about the release, DeLonge thanked shareholders in his organisation, and said “I am hoping to fund further research into the objects.”

“With today’s events and articles on my and @TTSAcademy’s efforts to get the US Gov to start the grand conversation, I want to thank every share holder for believing in us,” he said.

“Next, we plan on pursuing the technology, finding more answers and telling the stories.”

Many people surmised at that time that there were alien’s navigating those Unidentified Flying Objects (UFOs).

According to the New York Times, the clip from 2004 was filmed by two navy fighter pilots and shows a round object hovering above the water, about 100 miles (160 km) out into the Pacific Ocean.

Two other videos filmed in 2015 show objects moving through the air, one of which is spinning. In one, a pilot is heard saying: “Look at that thing, dude! It’s rotating!”

Let’s look at these videos described above

Obviously these aerial objects were not following any known laws of Newtonian physics . This author^​‡​ has always held that many new laws of dynamics are yet to be discovered or harnessed. One of them is Gravity. Yes we use Gravity of heavenly bodies to catapult or alter the course of rockets and satellites, enabling them to wander into the universe. This technique helps to save fuel and helps the spacecraft to remain navigable for a longer time. Hence Gravity is a force, a form of energy which is so powerful that it can hold Gigantic Planets, Suns and Stars together.

Yet my colleagues in the debate on Times Now program probably felt that if they were UFOs then they were to follow the same laws of physics which purportedly governed the rocket science of contemporary Space agencies like NASA. ISRO, Roscosmos and CNSA. Yes these Agencies have done remarkable work in outer space, but we are infants of science, if you compare yourself with the unimaginable size and extent of the Universe, and our place in it.

As beautifully put by Jonathan Marcus ^​§​ , “The fascination with the unexplained never goes away. And the UFO phenomenon is perhaps one of the most potent of these stories, linking uncertainty about worlds beyond our own to conspiracy theories about government and especially the US government. Down the centuries people have looked to the sky and tried to explain mysterious lights and objects.”

Roswell, New Mexico, currently known mostly through myths about aliens and UFOs, is a major Tourist destination with plethora of tourist attractions, skywalk and UFO museums, art galleries, Alien Zones, Inns and Hotels, was a little known place in 1947. It catapulted to fame when One morning around Independence Day 1947, about 75 miles from the town of Roswell, a rancher named Mac Brazel found something unusual in his sheep pasture: a mess of metallic sticks held together with tape; chunks of plastic and foil reflectors; and scraps of a heavy, glossy, paper-like material. Unable to identify the strange objects, Brazel called Roswell’s sheriff. The sheriff, in turn, called officials at the nearby Roswell Army Air Force base. Soldiers fanned out across Brazel’s field, gathering the mysterious debris and whisking it away in armored trucks. The farmer’s discovered debris, was initially described as a flying saucer, by the local media.

On July 8, “RAAF Captures Flying Saucer on Ranch in Roswell Region” was the top story in the Roswell Daily Record. But was it true? On July 9, an Air Force official clarified the paper’s report: The alleged “flying saucer,” he said, was only a crashed weather balloon, but later it emerge that it was part of a secretive balloon programme to monitor the Soviet Union.

However, in 1950, there was another twist to this public fantasy when the skeptics grew more numerous, when the Air Force conducted a series of secret “dummy drops” over air bases, test ranges and unoccupied fields across New Mexico. These experiments, meant to test ways for pilots to survive falls from high altitudes, sent bandaged, featureless dummies with latex “skin” and aluminum “bones”–dummies that looked an awful lot like space aliens were supposed to–falling from the sky onto the ground, whereupon military vehicles would descend on the landing site to retrieve the “bodies” as quickly as possible.  So we can see how much folklore is associated with the UFO mystery

Subsequently the testing base for advanced aircraft, known as Area 51 in Nevada, became the alleged centre for UFO research. For the conspiracy theorists this was where the US government sought to harness advanced alien technology.

Over the years many of the most outlandish theories have been debunked. But in 2017, the Pentagon did finally admit that it had a long-standing programme, now terminated, investigating alleged UFOs.

Undoubtedly the Idea of Aliens do fascinate people because of mystery attached to it. The event at Roswell got so embedded in public mind that it has inspired novels like Roswell High by Melinda Metz or even a recent television series Roswell, New Mexico , which is an American science fiction drama, named after the city . 

The inevitable question that follows is, are we a freak occurrence of life in the Universe, are we alone in this cosmos of Trillions of stars, galaxies, planets, exoplanets and what have you or is there life elsewhere too

DOI: 10.6084/m9.figshare.12571016
https://doi.org/10.6084/m9.figshare.12571016

More about this in subsequent articles

Part II will examine whether Science Fiction is really Fiction?

Part III will deal with the quintessential question: Are we alone in the Universe?

Also Read:

• The UFO sighting investigated by the police
• UFO ‘sighting’ becomes legend like King Arthur