Risk Assessment Report for Proposed Expansion of Surda Copper Mining Project

Transcription

1 RISK ASSESSMENT Risk assessment has been carried out for the proposed expansion of Surda mine, and based on the same, disaster management plan has been prepared which is as follows: During the operation of the underground mine, following risks have been identified. 1. Roof fall in the pit 2. Subsidence 3. Mine inundation 4. Fly rock from blasting operations 5. Fire (electrical and oil). 6. Possible Danger due to storage and handling of explosives Roof Fall in the Pit Accidents due to roof-fall occur in mines due to: Excessive weight of superincumbent strata Relative directions of cleats and headings Inadequate support Workings approaching faults or other disturbed strata Zones of high concentration while working near worked out area In the underground mine, working has been planned in a manner such that excessive weight is not generated in roof strata. Rock strength parameters (as given in tables below) indicate that superincumbent strata are competent. Roof bolting shall be carried out in stopes to bind the immediate strata. The worked out stopes are / will be stowed with mill tailings. Adequate support system shall be adopted for supporting drives, junctions and other work places. All relevant stipulations as specified in Mines Regulations and Acts shall be strictly adhered to. IIT Kharagpur has been entrusted with the work of formulating adequate support system and subsidence prevention. Design parameters for post pillar stopes are as follows: Vertical Level Interval : 37.5 m Length of stope along the strike: 100 m approx. Size of Post pillars : 4 x 4 m Spacing of post pillars Along the dip : 9 m Along the strike : 13 m Temporary support design Rock bolts : 1.5 m long; 15 x 1.5 m spacing Cable bolts : For sheared ground in 2.5 x 2.5 m spacing Page 1

2 Barrier Pillar thickness Sill Pillar thickness : 4 m : 5 m Photo a: Stope in Surda Mine filled with mill tailings Photo b: Hangwall Supported by Grouted Bolt in Surda Mine Subsidence Page 2

3 Surface subsidence is not expected because hydraulic stowing is practiced in conjunction with Cut and Fill method and also due to high in-situ rock strength (as indicated in the tables below) and sufficient depth cover. Additionally, depending on situation ore pillar is left, if required, between hanging wall and footwall. IIT Kharagpur has been entrusted with the work of subsidence prevention. No surface subsidence has been observed as yet due to working since In their preliminary report IIT Kharagpur has indicated that no surface subsidence is expected in the expansion or post expansion phase. Detailed Subsidence study report is awaited. The rock strength parameters of Surda mine as studied in CIMFR (erstwhile CMRS) are in Tables 1 and 2: Table 1: Engineering Classification of Rock Mass Rock Mass Quality Rock Mass Rating Sample Weighted Mean (Q) Avg. Rock Quality Weighted Mean (RMR) Avg. Rock Quality A Good Good B Good Good C Good Good D Good Good E Good Good Table 2: Compressive Strength of Rock Samples Sample No. Compressive strength (kg/ cm 2 ) Young s Modulus (kg/ cm 2 ) x x x x x x x x 10 5 Average x 10 5 CIMFR (Erstwhile CMRI) had carried out a study on measurement of deformation in post pillar at Surda mine. The findings of the study reveal that rock behavior remained unchanged. In one of the post pillar at 9L/300S a strain gauge based remote borehole extensometer was installed. The extensometer developed by National geophysical Research Institute (NGRI) was reliable and very sensitive (calibration factor = 66.4 microstrains per mm of movement). The extensometer rod was anchored at the centre of the pillar and the instrumented edge was fixed at the adge of the pillar. The lateral deformation of the pillar was monitored for a period of 560 days. During the Page 3

4 first 130 days after installation (unfilled stope) a gradual expansion of the pillar to a maximum of 9 mm was recorded. After filling the stope the recorded deformation was reduced from 9 to 5 mm due to lateral hydraulic pressure of the filled slurry. Subsequently after the fill settled the deformation gradually increased to 9 mm and remained almost steady without further expansion. The observation confirmed that there was no further yield after of the pillar after filling. Inundation In an underground mine, inundation occurs due to: Weak ground below surface water body leading to water entering mine Work zone may be overlain by water bearing strata and pillar fractures and faulty roof may admit water Surface water may enter through inclines, shafts or adits Contact with old water logged workings in the vicinity In case of Surda mine, the existing mine entries are located on a hill slope with necessary precautions for preventing storm water flowing down the hill slope from entering the mine. Following precautionary measures are undertaken in Surda Mine: A minimum distance of 60 m is maintained between mine workings and water. A careful assessment of the danger of inundation from surface water is made before onset of monsoon season every year and adequate precautions against such dangers are implemented. Effectiveness of precautions, obstructions in normal drainage system etc. are checked regularly. During rainy season, blockage of drains may occur, which needs to be cleared. Every entrance into the mine is more than 3.5 m above the High Flood Level (HFL) at that point. Fixation of danger mark of water level and effectiveness of communication are taken care of. Standing orders for withdrawal of persons from mine in case of apprehended danger have been framed and enforced. The mine has adequate pumping capacity. Standby pumping arrangements are also available. Blasting related hazards at underground work zone All precautions related to blasting, as prescribed in Metalliferrous Mines Regulation, 1961 and circulars issued from time to time by Director General of Mines safety (DGMS), will be followed before, after and during the blasting operations. Fire Page 4

5 Spillage of HSD and resultant fire constitutes a potential risk. At the mine there are no HSD storage facilities. No diesel powered machinery is used underground. HSD is present only in the tanks of vehicles operating at the surface. The quantity of the maximum fuel oil which can spill is not much and can be easily controlled. Sufficient nos. of portable fire-extinguishers have been provided in office buildings, stores below ground machinery, electrical sub- stations and especially at strategic locations near the fuel store, and DG sets to take care of any eventuality. The distribution and selection of extinguishers has been done in accordance with the requirements of Bureau of Indian Standards (BIS): All areas have been covered by manual protection system i.e. portable extinguishers, sand buckets. In addition to above, a fire station with one fire engine has been set up. In emergencies, if necessary additional fire fighting resources can be made available from HCL s Moubhandar plant. Other extensive fire fighting facilities are available at Jamshedpur. The Fire Station has following facilities: Fire Fighting agents Fire Fighting equipment Mobile Fire Fighting Equipment Safety equipments like fire shoes, fire blankets, breathing apparatus, portable detectors. Centralised Fire Alarm Panel Supervisory and control panels Emergency communication As soon as any fire is reported the shift-in-charge shall assume the function of disaster controller. In case of serious fire and depending on the gravity of the situation, the Mines Manager / General Manager (ICC) may be summoned to assume charge. Personnel trained in dealing with fires will be summoned. Meanwhile the hospital will be informed to standby to handle casualties. The fire area will be cordoned off till the fire is fully extinguished and remain so until all wreckage and debris is cleared away. Danger due to Storage and Handling of Explosives Surda has two explosive magazines. The magazine at Surda 3 shaft area has the capacity to store 450 kg explosives, 7000 m of safety fuses and 4000 detonators. The magazine at South Surda 4 Shaft area has the capacity to store 907 kg explosives, m safety fuses, 8000 detonators and 5000 m detonating fuse. Adequate safety zones have been provided as per statutory requirements while locating the magazines. The magazines have been constructed as per plans approved by Dept of Explosives, which include: Page 5

6 All dry vegetation within a 15 m radius has been cleared. Lightning arrestor has been installed on the magazine roofs. A safety zone of prescribed width around the magazines has been created. In summer, the temperature inside the magazines is monitored to guard against spontaneous fire. The manufacturing dates of all explosives stored in the magazines are carefully recorded so that no explosive whose shelf life has expired is kept in stock. All workers have been informed that in case of any fire, whosever notices the fire will sound the alarm and inform the shift-in-charge. The shift-in-charge will inform security personnel and arrange to evacuate all personnel, except those who are required for fire fighting, from the area. The fire brigade shall be summoned to deal with the emergency. Concerned district officials will be informed. The hospital will be informed to standby to handle casualties. A pit safety committee (PSC) has been constituted under Mines Rules 1955 is given below: Rule 29T Safety Committee: For every mine wherein more than 100 persons are ordinarily employed, the owner, agent or manager shall constitute a Safety Committee for promoting Safety in the mine: Provided that the Chief Inspector or an Inspector may by a general or special order in writing require the owner, agent or manager of any group of specified mines or of all mines in a specified area to constitute a group Safety Committee in such manner and subject to such conditions as he may specify in the order. Rule 29U Composition of Safety Committee: The Safety Committee shall consist of :- (a) The Manager who shall be the Chairman ; (b) Five officials or competent persons of the mine nominated by the Chairman ; (c) Five workmen nominated by the workmen of the mine in accordance with the procedure prescribed in clause (a) of sub-rule(1) of rule 29Q for nomination of Workmen s Inspector; (d) Workmen s Inspector where so designated; and (e) The Safety Officer, or where there is no Safety Officer, the senior most mine official next to the manager, who shall act as Secretary to the Committee; Provided that any other official, competent person or work person may be co-opted by the Chairman as a member of the Committee on any day or days of the meeting, if considered necessary. Rule 29V. Functions of Safety Committee - The functions of the Committee shall be- (1) To discuss remedial measures against the unsafe conditions and practices in the mine as pointed out in the reports of Workmen s Inspector or otherwise Page 6

7 brought to the notice of the Committee and make appropriate recommendations; (2) To consider, before commencement of operations in any new district of mine or commissioning of new electrical or mechanical installation or introduction of new mining technique, the proposed Safety and health measures including related codes of practice and to make appropriate recommendations; (3) To discuss the report of inquiry into accident and make appropriate recommendations; (4) To formulate and implement appropriate Safety campaign based on analysis of accidents; (5) To meet at least once in 30 days to consider the matter placed before it and any other matter that may be raised by the members and make such recommendations as it may deem fit; and (6) To serve as a forum for communication on Safety and occupational health matters. Rule 29W Implementation of recommendations of the Safety Committee: The owner, agent or manager shall, within a period of 15 days from the date of receipt of the recommendations of the Safety Committee, shall indicate to the secretary to the Safety Committee, the action taken to implement the recommendations.] Training on occupational safety and health is imparted by the mine s Safety Officer, the Medical Officer and the external Occupational Health Physician & Consultant. The occupational diseases which can occur among the mine s workers are Silicosis due to dust inhalation Hearing loss due excessive noise The chances of silicosis due to dust inhalation have been minimized by effective dust suppression in underground work areas. The partially crushed ore is still moist when brought to the surface thereby reducing fugitive dust generation during ore handling. Wearing of dust masks is mandatory for workers engaged in drilling to minimize dust inhalation and wet drilling is carried out in the mine. The chances of hearing loss are very less as blasting and related operations, which produce maximum noise are carried out only after ensuring that all workers are at a safe distance from the blasting site. The Occupational Health and Safety Medical Officer is responsible for early identification of onset of occupational diseases and recommend necessary remedial action to prevent further damage. HCL pays for all medical tests (PME) and treatment of non-occupational diseases, from which the workers are suffering as per prevailing rules and regulations of Govt. of Jharkhand. In case of health impairment due to illness or injury suffered at work place, HCL will compensate the affected worker(s). The amount of compensation to be paid will be Page 7

8 calculated in accordance with the applicable formula given in the Workmen s Compensation Act. As mentioned earlier, all new recruits undergo an initial medical examination and the findings are recorded in the concerned worker s medical file. Every 5 years the workers undergo a PME and the results of the same are recorded in their respective medical files. All workers medical files are maintained for the entire duration of their service in the company and even beyond. The Safety Officer is responsible for the purchase and issue of all personal protective equipment (PPE) e.g. shoes, helmets, various types of gloves, aprons, dust respirators, ear plugs, goggles etc. taking employee strength into consideration and distributed to both company employees and contractors employees. Safety boots are issued every 6 months, helmets every 3 years and other PPEs as per requirement. If any PPEs are damaged before their scheduled replacement, fresh equipments are issued. Even after the mine s closure, if any worker is diagnosed with a disease resulting from exposure to hazards while working at the mine, he will be compensated as per prevailing company rules. The roles and responsibilities of HCL personnel in matters safety is as follows: Chairman cum Managing Director Director (Mining) General Manager (ICC) Chief Safety Officer Mine Manager Workman Inspector Page 8