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Four Sandvik jumbos excavate India’s first underground crude oil storage cavern Indian contractor Hindustan Construction Company Ltd is using four Sandvik DT 820 underground drill rigs to construct the country’s first underground crude oil storage cavern, at Vizag in southern India. Four Sandvik DT 820 underground jumbo drill rigs are being used for the construction of India’s first underground crude oil storage cavern, located at Visakhapatnam in southern India, with two Sandvik DX 700 surface drill rigs also being used benching work in the same site. The cavern is being constructed under a Rs 375 crore (US$75. million) contract by Mumbai-based Hindustan Construction Company Ltd (HCC) for Indian Strategic Petroleum Reserves Limited, a subsidiary of the Oil Industry Development Board under the Petroleum Ministry. Located at a hill named Dolphin’s Nose, the cavern is being constructed on land belonging to the Eastern Naval Command in Visakhapatnam (usually abbreviated to Vizag), and will have a storage capacity of 1. 33 million tonnes of crude. Vizag, located on the east coast and considered the eastern gateway to India, was selected as the site because it has a large seaport for the import of oil.
Adjacent to the cavern site is Southeast Asia’s first underground LPG storage cavern, commissioned early last year and which also used Sandvik jumbos during construction. HCC began work on the cavern in January of last year and is working to a 36-month schedule. The contract covers detailed engineering and design, underground excavation, access tunnels, water curtain galleries, main storage caverns, shafts and associated underground civil works. The contractor’s project manager Ramana Rao says that there are two caverns for the storage of the crude, both 30 m in height and 20 m wide, together ith associated tunnelling. High-sulphur crude will be stored in one cavern. Complete length of the underground works is more than 3 km, and the amount of rock being excavated is about 5 million tonnes. The floors of the caverns are 60 m below mean sea level, which means that the workings are accessible via an inclined access shaft at ground level, but with the hill above the site reaching an elevation of 130 m, two large shafts have been sunk to house the operating equipment for the cavern.
Mr Rao says that the rock strata is khondalite, a form of sandstone that follows an arc through India’s southern and eastern states and which has been used throughout the subcontinent’s history for architectural construction and ornamentation. HCC is using the four Sandvik jumbos simultaneously for much of the time, as the drilling and blasting is being undertaken on several fronts. “Our logistics are designed to supply power and water to four headings simultaneously, and to remove the rock and do the shotcreting,” he says. The four Sandvik machines are therefore working within this cycle. ” The jumbos are drilling at least 150 holes per blast cycle, at depths of between 2 m and 4 m, depending on the section of the cavern on which they are working. It takes on average two minutes to drill one hole, with the holes closely following the tunnel profile. With a tunnel profile of 11 x 8 m holes are packed with a total of 480 kg of explosives. A 10 x 8 m profile requires 473 kg, and an 8 x 8 m profile needs 365 kg.
The drilling per blast cycle takes around six hours, and rock bolting is simultaneously being undertaken from a basket fixed to the jumbo. Once the drilling is complete, the jumbos are moved out of the tunnel where they are washed down after each drilling shift. With the blasting and rock removal complete, the jumbos are moved back into position for the next cycle. Mr Rao says that with work proceeding 24 hours a day, the production cycle allows three blastings to be carried out during a two-day period, and that each blast advances the work by 3. 5 to 3. 8 m.
HCC’s project mechanical engineer Kaushal Kumar Sharma says that the machines are hosed down at the washing area next to the access shaft, and that routine maintenance is undertaken once a week. “We inspect the hoses and linkages and the drill bits, and oil and lubricate the machines. Our own staff do this, but Sandvik has an onsite presence and works very closely with our maintenance and operating teams. ” The jumbos were supplied to HCC by Sandvik India, whose senior engineer on site, Harish Pokharkar, says that spare parts are supplied via the company’s Pune headquarters.
The two Sandvik DX 700 surface drill rigs are being used around the two cavern shafts, where they are undertaking vertical drilling for the benches that are being cut into the hillside. Mr Pokharkar says that both machines are fitted with 45 mm R32 drill bits, with an R 38 shank adapter and R 38 and R 32 drifter rods. “The DX 700s are drilling down to depths of 21 m,” he says. “We have a grinding facility for the drill bits installed at the site, and we have recorded that by grinding we are achieving 30 percent extra life with the bits. We have also ascertained that machine availability has been slightly over 96 percent per month. ” The crude oil cavern at Vizag is one of three such caverns planned by the Indian government, with a storage capacity of five million . Two other caverns will be at Mangalore and Padur, with the crude designed to act as a buffer in the event of emergencies or disruptions in supply. All three projects will be operational by 2012. Box The Sandvik DT 820 is a two-boom electro hydraulic jumbo for fast and accurate drilling in tunnelling and cavern excavation of 12 to 110 m2 cross sections.
It is equipped with an HLX5 rock drill and a TB 90 universal boom, which gives a large optimum shaped coverage and full automatic parallelism. The booms can also be used for cross-cutting and bolt hole drilling. An optional basket boom for bolting and utility works is available. The four-wheel-drive centre articulated carrier ensures rapid and safe tramming with good balance. – Ends – SAND109A. doc FOOTNOTE TO EDITORS This press release is available on the Joem Promotions website:www. joempr. om Issued on behalf of Sandvik Mining and Construction by Joem Promotions. For further details please contact: John Hooperor Nina Lehtonen Joem Promotions Sandvik Mining and Const The Court Yard, Sondes Road Pihtisulunkatu 9, Deal Kent CT14 7BW UK P O Box 100 SF-33311 Tampere Finland Tel:+44 (0)1304 368688 Tel: +358205444059 Fax:+44 (0)1304 375181 Fax: +358205444533 email: john. hooper @joempr. demon. co. uk email:nina. [email protected] com