Two 600 feet deep shafts, dug in 1981-82 by 113 Engineer Regiment, made Pokhran II possible in 1998
Maj. Gen. Mrinal Suman (retd)
113 Engineer Regiment located at Jodhpur was assigned the task of sinking two 600 feet deep shafts in the Pokhran Ranges for testing a 45 kt fusion bomb (also called hydrogen or thermonuclear bomb) and a 15 kt fission bomb (atomic bomb). The shafts were dug in 1981-82. Due to international pressure, the tests had to be deferred. However, regular maintenance of the shafts was carried out by different regiments till Pokhran II took place in May 1998.
For 113 Engineer Regiment, it was an unprecedented assignment. To sink shafts hundreds of feet deep was a huge challenge — more so as none of the officers had ever seen a shaft or visited a mine; nor had anyone studied mining engineering which is a specialised course.
A word about shaft sinking will be in order here. To approach underground mineral seams, a vertical opening (shaft) is provided from the surface to the mining zone. These shafts are used to carry men, material and equipment to the mining zone; as also, to haul the extracted ore to the surface. Being the lifelines of all underground mines, shafts are sunk with exacting technical specifications. Every mining manual terms shaft sinking to be the most dangerous and hazardous task. It requires domain expertise and specialised equipment. There are a handful of shaft sinking companies in the world, normally called ‘sinkers’. All mining companies outsource shaft sinking operations to them.
The late Lt Col K.C. Dhingra (later rose to the rank of Major General) was the commanding officer of the regiment. Two task forces were constituted and the work started at the selected sites in February 1981 without much fanfare. After having cleared the sand over-burden, we encountered a conglomerate consisting of gravel, sandstone and silt stone. Digging was tough as the drill used to get stalled in the bores. We also encountered shale, a fine-grained clastic sedimentary rock. It is a mudstone that is fissile and laminated. After every 10 feet of depth, we had to pause to stabilise the shaft walls with steel jackets and rock-bolts.
Water seepage was first encountered at 60 feet depth. Although the quantity of inflow was limited, it still posed problems in digging. Water had to be collected in a sump and pumped out at intervals. Initially, we used pumping sets of our regimental water supply equipment, but soon found them to be unsuitable due to limited delivery head.
A few sump pumps were procured from the market. The work on shaft digging continued for some time. As the sump pumps need 220 volt electric power, they could be used only after getting all the men out, lest they get electrocuted. The progress became unacceptably slow as frequent movement of men (in and out of the shaft) wasted considerable time.
As we dug down, difficulties increased. At about 100 feet depth, water ingress increased substantially. Within an hour, water level used to rise to five-six feet. Drilling became impossible. We realised that dewatering had to be done concurrently with drilling and mucking (removal of blasted earth/rock). Consequently, all electric devices (including submersible pumps) got ruled out. As the water inflow became unmanageable, work at both the shafts came to a halt. Ghosts of Pokhran-I (the incomplete shaft had to be abandoned due to water woes) started haunting us.
It was a nightmarish situation. Water had indeed posed a major challenge that appeared to defy all solutions. Though we were at a loss for a while, we were determined not to let the country down. But the soldiers of 113 Engineer Regiment are not ‘quitters’. They never give up. After some brain-storming, we decided to learn about the methodology of dewatering, as followed by the professional shaft sinkers. For that, we needed to visit a few mines.
Col Dhingra convinced the authorities and permission was received to visit Khetri copper mines and Zawar zinc mines, the nearest operational mines. To maintain secrecy, cover stories were made up. The two shaft commanders (Major S Jagannathan and I) accompanied Col Dhingra.
Zawar mines are located 40 km from Udaipur in Rajasthan. We were received with a certain degree of unease. It was learnt that the local trade union had served a strike notice and our presence was seen as an effort by the government to hand over essential functions to the army. The alibi suited us. We spent three days to understand all operations and the visit proved to be highly rewarding.
During our second night at Zawar mines, we came across a pump throwing water upwards with considerable force. On querying, it was found to be an air operated double diaphragm (AODD) pump. It is a positive displacement pump that uses compressed air as the power source. Reciprocating elastomeric diaphragms and check valves are used to pump fluid. The liquid chambers are filled and emptied by fluid that is drawn through a common inlet and discharged through a single outlet.
We learnt that AODD pumps are much easier to use and maintain. They can even run dry without getting damaged, hence no priming is required. The pump we saw belonged to Cemindia Company, to whom the task of sinking shafts had been outsourced. Cemindia was a subsidiary of the Cementation Company Limited of the UK).
We immediately understood that we had to procure AODD pumps if we were to make further progress. They were indispensable for our task. However, we were disappointed to learn that AODD pumps were not manufactured in India. Import implied unacceptable delay. Moreover, the government was unlikely to give import clearance due to secrecy concerns.
While taking a round of the mine, we saw an operator dismantling and maintaining an AODD pump. We watched him in fascination and asked several questions about the pump’s functioning. It was discovered that Cemindia was procuring spare parts from a local source. After some deft probing, we manage to get details of the said source, i.e. Rajasthan Heavy Engineering Works (RHEW) in Udaipur. It turned out to be a priceless input.
After returning to Jodhpur, Col Dhingra requested New Delhi for urgent import of AODD pumps. As expected, the response was not encouraging. Left with no alternative, we toyed with the idea of buying spare parts and assembling the pumps in the regiment. To explore that route, we needed to contact RHEW at Udaipur. It was a long shot, but well worth trying as we had little to lose.
Capt. P.P. Sharma (later Colonel), our diligent Technical Equipment Officer, accompanied me to Udaipur. The owner, Sharma received us warmly. We told him that the army was constructing underground storage facilities in the hills near the border and the work had got stalled due to water flooding. When we requested him to supply AODD pumps to us, he wondered as to how did we get to know about him.
He accepted that he was casting all the components as per the drawings given to him by Cemindia; and could easily assemble fully functional pumps. However, he declined to supply them to us, considering it to be an unfair act. We tried to convince him that he was not harming Cemindia’s commercial interests in any way as we were not its competitors. He appeared to soften a little. We felt encouraged. Capt Sharma asked him if he could ever sleep in peace after declining to support the soldiers fighting on the border. The statement appeared to have had the desired impact.
After consulting his son, Sharma agreed to help us out. He told us to place orders on him for various components with different nomenclatures. He promised to deliver fully assembled and configured pumps to us. We thanked him profusely, heaved a sigh of relief and informed Col Dhingra.
However, our euphoria was short lived. Sharma informed us that he did not manufacture elastomeric neoprene (synthetic rubber) diaphragms and had been receiving them from Cemindia for fitting in the pumps. We got stumped. AODD pumps without diaphragms were of no use. After much persuasion, he gave us the address of Amar Rubber Works at Thane, the makers of diaphragms as per Cemindia’s specifications.
After getting a nod from Col Dhingra, we proceeded to Thane to meet the owner. We told him that the army had been carrying out dewatering of underground storage facilities near the border with imported AODD pumps. We asked him for diaphragms for our pumps. Appearing ready to help the army, he offered rubber diaphragms that he had developed. When queried, he admitted that his diaphragms could perform only up to 30 feet delivery head. They were of no use to us as we needed much higher delivery head.
When probed further, the owner revealed that he had been making reinforced neoprene diaphragms for Cemindia but declined to supply them to us without Cemindia’s permission. All our coaxing was in vain. He kept expressing his helplessness as it was a proprietary item. At the end, he advised us to contact Saxena, the concerned officer in Cemindia’s Mumbai office.
We decided not to give up without knocking at the doors of Saxena. He received us well with coffee. We explained the problem of flooding of underground facilities of the army and highlighted the difficulties faced in getting replacement of diaphragms for our AODD pumps. We informed him that we had already contacted Amar Rubber Works for neoprene diaphragms but were declined supplies without Cemindia’s permission.
He smiled and asked, “Do you want me to lose my job by giving proprietary item to you? Our company dominates the shaft sinking business because of such proprietary equipment.” I told him that we were not his commercial competitors and his company’s business had nothing to fear from the army. After much persuasion, he promised to speak to his company head. While getting up, with disappointment writ large on our faces, I fired the last shot, “If you, as an Indian, are not ready to help your army, why would a foreigner help?”
He looked at our faces for a while and told us to sit down. He picked up the phone and spoke to the owner of Amar Rubber Works in hushed tones for some time. We could not hear the conversation but realised that they were discussing a way out. He put the phone down and told us, “Visit Amar and he will do the needful. Your orders should not mention neoprene at all”. We understood their plan and were ecstatic. His parting words were, “Remember, I also stand by my army.”
Pumps and diaphragms reached us within a week. They were installed in the shafts soon thereafter. As their effective head was only 90 feet, we had to pump out water in stages. For that, narrow steel platforms (called buntons) were anchored in the shaft wall as intermediate pumping stations. As we went down, additional stages were created.
Captain S.B. Pendse, our ingenious technical brain, established a reliable grid of pneumatic power with a bank of army’s standard compressors of 210 cfm 100 psi capacity. Uninterrupted supply of compressed air was thus assured to both the shafts. We did face initial teething problems. Once we mastered the dewatering technique, there was a no looking back. RHEW and Amar Rubber Works never let us down. In fact, they improved the quality of their products with in-house innovations. Their supplies were regular, and most surprisingly, they never sought an increase in price.
After reaching the specified depth, we had to dig a large side-chamber. We had anticipated this requirement as a powerful nuclear device is always placed under natural rock strata to contain blast effect, thermal radiation and radio-active fallout. The side chambers were duly completed without much difficulty and completion report submitted. The task was completed well before the stipulated time. What is more, the scientists were overjoyed as they had got two deep shafts against their initial demand for one.
As water could have damaged their sensitive instruments and devices, the scientists wanted the chambers to be totally dry. By then, we had become adept at managing underground water. To demonstrate the dryness of the chambers, we dressed them up as sitting rooms with carpets and folding chairs. The scientists were exhilarated to have tea at a depth of over 600 feet.
Although close to four decades have passed, the memories of our struggle with water are still fresh. Water management was, undoubtedly, our biggest challenge. The support extended by Sharma and Amar Rubber Works was invaluable in overcoming the forbidding water woes. Our regiment owes a big ‘thank you’ to them.
Sinking of deep shafts, lining the walls and preparing side chambers in such a compressed time frame had been a monumental achievement. As India has declared self-imposed moratorium on nuclear tests, need for deep shafts will never arise again. In other words, the feat of 113 Engineer Regiment will remain unequalled. As the then Chief of the Army Staff, General Krishna Rao had stated, 113 Engineer Regiment contributed to scripting the history of nuclear India: a unique distinction indeed.