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by Rajan K Pillai, CEO ISPRL

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1 by Rajan K Pillai, CEO ISPRL
Safety Measures Adopted in Underground Cavern Storage of Crude Oil to Prevent Disasters by Rajan K Pillai, CEO ISPRL 31st January 2014

Underground Rock caverns for storage of hydrocarbons in India Risks and Hazards in Underground Caverns Construction Risks. Operations Risks. Mitigation methods Construction phase Operations phase

3 Underground Rock caverns for storage of Hydrocarbons in India

4 Isometric drawing of SALPG Cavern
Access Ramp (AR) Upper Connection (UC) Intermediate connection (IC) Upper Shaft Connection (USC) Access Shaft (AS) Operation Shaft (OS) Lower Shaft Connection (LSC) Water Gallery – Operation Shaft Connection (WOC) Water Gallery – Access Shaft Connection (WAC) Water Curtain Gallery (WCG Sump which houses the submersible pumps Lower connection (LC) Operation Shaft is 201 meters deep

5 The Isometric View of the Visakhapatnam UG Facilities
The view shows the various parts of the facility which includes access tunnels, water curtain galley, interconnection tunnels & shafts. Capacity is 1.33 MMT Total tunnelling including shafts exceeds 7 kilometres 5

6 The main galleries are 913 m long
Isometric View of Mangalore UG Facilities Capacity is 1.5 MMT The main galleries are 913 m long Total tunnelling including shafts exceeds 9.2 km.

7 Isometric View of Padur UG Facilities
The Padur project capacity is 2.5 MMT. The total excavation is in excess of 36.8 lakh cu m. The facility has 6 storage galleries that are 700 m long and 2 storage galleries that are 650 m long. Entire excavation has been completed A jumbo jet in the foreground for comparison Total tunnelling including shafts exceeds 13.7 km(only top heading).

8 Typical Cross Section of the Main Cavern
The height of the caverns is almost equivalent to a ten storey building 7 m Top Heading Bench 1 7 m Bench 2 Varies Bench 3

9 A view of the Padur Cavern Gallery
The galleries are 30 meters tall and 20 meters wide. There are eight galleries. Six galleries are 700 meters long and three are 650 meters long. This photograph is of one of the completed 700 m gallery Photograph of a gallery in the Visakhapatnam Cavern

10 The excavated rock debris can fill 2.5 million standard 10 ton trucks
Quantum of Excavation in ISPRL Caverns Item Vizag Mangalore Padur Total Access & Connect. tunnels (meters) 1632 1847 3429 6908 Water Curtain Tunnels (meters) 1804 3560 3881 9245 Main Cavern (meters) 3250 3572 5632 12454 Shaft lengths (meters) 405 232 580 1217 Total Chainage (meters) 7091 9211 13522 29824 Borehole Nos 275 489 514 1278 Borehole length (kilometers) 17.2 32.0 26.9 76.1 Excavated qty in Million tons 5.4 6.3 9.8 21.5 The excavated rock debris can fill 2.5 million standard 10 ton trucks

11 Approx Quantum of Material used in ISPRL Projects
Item Visakh Mangalore Padur Total Concrete in Cu. m 50464 35862 91423 1,77,749 Shotcrete in Cu. m 37395 21778 35072 94,245 Rock Bolts in tons 2360 1981.7 2226 6,568 Reinforcement steel in tons 1810 1565 6991 10,366 Explosives used in tons 2330 2100 3865 8,295 The material would required a huge transport fleet for movement from one spot to the other within the sites. In addition to the materials, workforce also needs to be moved

12 Comparison of the Excavation Progress Curves
Projects were started on different dates, but for comparison, zero dates have been matched

13 Risks and Hazards in Underground Caverns

14 Geological Risks- During Construction…….Slide1
Over Breaks and Rock falls Over breaks and rock fall are major safety concerns during construction and can cause fatalities and can drastically slow down progress.

15 Since this fault was below the bench it could not be identified.
This bench was excavated

16 When the bench was removed the rock wedge started sliding
Wedge on the wall started sliding When the bench was removed the rock wedge started sliding

17 Almost 10,000 tons of rock came crashing down and resulted in one fatality.

18 Area of brittle fracture
The triangular block which slid down Smooth face

19 Man standing near rock slide area
Weakness zone, consisting of highly sheared and disintegrated material


21 Geological Risks- During Construction…….Slide3
Water bearing zones or aquifers zones could result in large water ingress into the caverns or shafts. Such a problem was encountered in the SALPG cavern project. Water ingress into shaft Underground Aquifers

22 Large seepage of water into the Padur cavern during construction

23 Traffic Hazards- a major concern during construction
. Large number of equipment –required for excavation of the caverns. Movement of equipment adds to the risks

24 Equipment handling during Construction

25 Drilling & Blasting Method of Excavation
Jumbo used for drilling holes in rock Holes are charged with explosives after drilling and controlled blasting carried out

26 Drilling & Blasting Method of Excavation

27 Explosives handling- a concern during construction
In ISPRL the quantum of explosives that have been used is huge. We have use approx 8300 tons of explosives in our projects. When handling such large quantities of explosives, there is the risk of accidental blasts or misfires. There is also the risk of the explosives being pilfered during their transportation and use and thereafter being used for undesirable activities.

28 Vibration due to blasting – another concern.
The vibrations can be large if the quantum of explosives used is large. Vibrations can cause damage to the surrounding rock and effect the stability of the cavern. Vibration can also cause damage to surrounding surface structures. Blast induced ground vibrations can create social problems as they could disturb the people residing in the vicinity

29 Fumes and dust – a health hazard
Air borne dust particles when inhaled into the lungs can lead to various diseases, like bronchitis. There is particular concern that silica dust can lead to cancer. Crystalline silica is a common mineral present in sand stone, quartz and many other rocks During blasting operation fumes are produced. These fumes can be harmful to humans working inside the tunnels. The oxygen levels in the cavern can become low after the blasting operation and therefore poses a health hazard

30 Risks During Operation Phase
Loss of Containment Due to hydro geological reasons. Due to sabotage/failure of aboveground facilities Intermingling of different grades of crude oil. Fire/Explosions within caverns due static electricity discharge.

31 Mitigation Methods

32 Mitigation methods-Construction Phase …Slide 1
Rock bolts To ensure there is good stability of the cavern, rock bolts need to be installed and shortcrete applied. Poorer the rock strata, larger is the support requirement. Shotcrete

33 Large number of optical targets installed in the caverns
Large number of optical targets installed in the caverns . The bright spots are the optical targets Monitoring of the movement of the walls of the cavern using optical targets

34 Pre-Grouting in excessive water bearing zones
Pre-Grouting involves drilling a number of holes on the face and pumping cement paste under pressure into them till sealing is achieved. High permeability and water bearing strata could result in higher grouting and slow excavation progress.

35 Mitigation Methods – for Traffic Hazards
The cavern access tunnels and junctions to be well designed. Only specialized equipment to be used for evacuating muck (equipment with all safety features) Drivers to be imparted specialized training for underground works. Tool box talk to be made mandatory before start of work. Housekeeping to be one of the important requirements in contract management. Good rewards and punishment system should be planned .

36 Mitigation Methods – for explosives handling
Obtaining all applicable Legal Permissions as per “The explosive Act 1884” and Explosive Rules 1983. Putting in place a well defined explosive handling procedure and clearly describing steps to be followed during transportation, storage and handling of explosives. Ensuring qualified & authorized personnel only handle the explosives. Reconciliation of all explosive material and authentication of reconciliation statement by Magazine In charge.

37 Mitigation Methods – for excessive vibration
The vibration problems can be best controlled by having properly designed blast patterns. The number of blast holes, their length, amount of explosives to be charged and the detonation type. Once these parameters are controlled properly, they can reduce vibration levels drastically. After ensuring properly designed blast patterns, ensure the vibration levels are monitored on a regular basis. The site to be trained to ensure that only smooth blasting techniques are followed at all times inside the caverns.

38 Mitigation Methods – for fumes and dust
Huge motor driven air blowers installed at the entrance of the caverns to pump in fresh air to the blasting faces and caverns Huge flexible ducts inside the access tunnels which carry air to the blasting faces and caverns

39 Mitigation Methods – Loss of containment
Piezometers Water table It is important that during the operation phase, the water table is monitored at all times

40 Mitigation Methods – Failure of AG piping
Failure of pipeline. LPG starts to leak Water Column of water acts as a seal and shuts off cavern Gas LPG

41 Separation of different products to be stored
Water Curtain Boreholes Water curtain tunnels Mean Sea Level(MSL) Storage Caverns

42 Mitigation Methods – For fires /explosions
The caverns for products other than LPG are intertized by filling the vapour spaces with either nitrogen or flue gases. The oxygen content reduced to less than 8% . This will avoid any explosions caused by static electricity Nitrogen or flue gas Crude oil Storage Caverns

43 We have Miles to go Thank You
Measures Adopted for Monitoring the SAFETY & DISASTERS in Underground storage caverns We have Miles to go Thank You

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