Workplace location Is the tunnelling work carried out in a remote or isolated place? How accessible is it in an emergency and how far away is it from medical facilities? Can a person be rescued immediately without relying on emergency services? Are there areas where special emergency provisions like emergency rescue cages and the means to extract people from difficult locations like the base of a shaft needed? Have safe places and assembly points been identified? Escape routes Table 5 lists questions and information on escape routes. Roles and responsibilities Who should be allocated roles and responsibilities in an emergency e.g. area wardens? Who has the relevant skills for specific actions in an emergency? Training Who requires regular and on-going training? When should this be provided? Does the training include an understanding of the emergency plan and actions to be taken in an emergency, escape options and emergency equipment? How will workers who enter the tunnel be trained in entrapped procedures, like remaining calm, alert and making conservative decisions? Communication How: can workers doing tunnelling work communicate in an emergency will clear lines of communication between the person authorised to the emergency response and people at the workplace be maintained, and will alarms be activated and who will notify people at the workplace? Is there a system in place to identify who is underground, like tag boards or electronic tagging? Have you clearly displayed the workplace site plan showing where fire protection equipment is stored, the location of emergency exits, assembly points and emergency phone numbers? Rescue equipment Has rescue equipment been selected based on the nature of the work and the control measures used? Can it carry out the planned emergency procedures? Is rescue equipment kept close to the work area so it can be used quickly? Capabilities of rescuers Are rescuers properly trained, fit to carry out their task and capable of using rescue equipment? Have emergency procedures been tested to demonstrate they are effective? First aid Is first aid available for injuries associated with falls, cuts and crush injuries? Are trained first aiders available to use the equipment? Roles for the local emergency services Can you rely on local emergency services for rescue? Other arrangements should be made if they cannot respond within a suitable time. How will the local emergency services be notified of an incident?
The following section describes most tunnelling methods and activities and provides examples of specific hazards, risks and control measures to be considered in addition to the common hazards, risks and control measures. Specific guidance on risk control measures for excavation and construction work is in the Code of Practice: Excavation work and the Code of Practice: Construction work. Excavation by hand Most tunnelling work is partly or totally mechanised. Excavating by hand is generally limited to small sections within larger workplaces like a small shaft, sump or drive-in area with limited access and possibility for mechanisation. Control measures must be implemented to eliminate or minimise, so far as is reasonably practicable, the risks associated with excavation by hand. Table 7 Specific hazards, risks and control measures – excavating by hand Hazards and risks Control measures small work areas hazardous manual tasks e.g. extra physical lifting and activity falls from heights from non-mechanised access falling objects from working: near the worked face under unsupported ground installing bolts, sets and lattice girders for ground support vibration effects on the body from using hand tools like rock drills or jack picks noise from working near air tools and drills contaminated ground or groundwater dust from working near the face heat stress from physical exertion crush injuries from small mobile plant contact with electric lines including electrical shock from services not removed or implementing regular face and scaling inspections using: tools with non-conductive handles mechanical lifting gear, winches, rigging systems PPE like rubber boots, insulating gloves and hearing protection restricting entry to work area reducing worker numbers in work party monitoring daily exposure limits on vibration providing training and information like SDS supplying: lighting and ventilation adequate for the task drinking water and managing fatigue Excavation using plant Control measures must be implemented to eliminate or minimise, so far as is reasonably practicable, the risks associated with excavating using plant. Table 8 Specific hazards, risks and control measures - excavating using plant Hazards and risks Control measures
works, like oxy cutting and welding using: fire resistant hydraulic fluid and fire resistant power cables for high voltage supply fire retardant tail shield grease Gas accumulation using gas detection and lock out devices Ground support installation including access, ring build, segment handling with cranes, annulus void filling and vibration using remote control bolting correctly operating segment feeder and handling devices including having operators visually check area before use ensuring: workers are competent in the use of segment handlers and follow manufacturer’s instructions the ring builder can visually see rams when moving them use of exclusion zones so no work is done under unsupported ground limbs are kept well clear of plant inspecting installed ground support Heat exposure supplying: ventilation chilled drinking water managing fatigue Irrespirable atmosphere including toxic fumes providing self-rescuers and checking their operation regularly using emergency seals Noise exposure using: hazard lights audible alarms hearing protection Pressurised hydraulic systems including pressure release through screw conveyor discharge gate using tunnel brackets designed to ensure the service pipes and cables are correctly supported marking cut off valves clearly inspecting hoses regularly for wear and replacing them if necessary establishing communication protocols when pigging the slurry lines having a sealable spoil screw conveyor tube inspecting pipes, seals and packing before commencing operations maintaining separation between workers and hose joints where reasonably practicable using eye protection for operators Slip and trips including risks from greasy walls and spillage from polymer use ensuring housekeeping procedures are followed using grated walkways having spill kits available
APPENDIX F – ATMOSPHERIC CONTAMINANTS Gases or fumes commonly found in excavations are listed in Table 41. Table 41 Origins of gases and fumes Gases or fumes encountered Origin Methane, hydrogen sulphide Peaty ground and decaying organic matter Carbon dioxide, hydrogen sulphide Filled and made ground Carbon dioxide, methane, hydrogen sulphide Reclaimed land and tip fills Natural gas and carbon dioxide City streets, leading gas reticulation pipes Carbon monoxide, carbon dioxide, hydrogen sulphide, sulphur dioxide, methane Thermal areas, combustion Petrol fumes, LPG, kerosene Petrol installation, service stations, underground filling stations Common sources for hazardous atmospheric contaminants are listed in Table 42. Table 42 Origins of other atmospheric contaminants Activity Contaminant Harmful component Hot work Welding or cutting fumes Metal oxides, oxides of nitrogen, ozone, fluorides. Operation of internal combustion engines Exhaust fumes Carbon monoxide, carbon dioxide, diesel and other particulates, oxides of nitrogen, fuel vapours, aldehydes and hydrogen sulphide. Oxygen depletion can occur. Excavation Rock dust Crystalline silica and other mineral dusts. Shotcreting, rock bolting, concreting, grouting Cement dust or accelerator Cement dust, ammonia and chemical accelerating compounds. Battery charging Vapours Flammable gas, acid fumes. Shot firing Blasting fumes Crystalline silica dust, ammonia, oxides of nitrogen, carbon monoxide, sulphur dioxide, carbon dioxide. Table 43 provides a guide to the effects and consequences of some common atmospheric contaminants at various concentrations. Table 43 Effects and consequences of some common atmospheric contaminants