Code Of Practice Excavation 6l4u3g

295186 Workcover (before impos)

22/3/00 9:43 AM

Page 2

Code of Practice Excavation

31 March 2000

WorkCover Authority of NSW GPO Box 5364 Sydney NSW 2001

Cat. No. 312 ISBN. 0731388771


22/3/00 9:43 AM

Page 4

Contents Page No.

DON’T RISK IT

1.

Introduction

3

2.

Planning and preparation

4

3.

Work systems and control measures

10

4.

Protection against contaminated environments

35

5.

Inspection and maintenance of plant and equipment

42

6.

Training and instruction

44

7.

Personal protective equipment (PPE)

45

8.

Legal requirements

48

Definitions

• Dial Before You Dig is a free referral service for receiving information on underground pipes and cables before you start work. • All major utilities are including Energy Australia, Integral Energy, Telstra, Optus, AGL and Sydney Water. • Digging without maps means exposing yourself and your contractors to danger. • Unexpected cable strikes can slow your job down. • Damage to underground utilities can affect your insurance.

Appendix 1

Checklist - Hazard Identification, Risk Assessment and Control Measures

Appendix 2

Example of a Hierarchy of risk control measures

Appendix 3

A typical example of a safe work method statement

Further Information

• Dial 1100 between 8am and 6pm on working days • Fax 1300 652 077 anytime

THIS

IS A FREE SERVICE 2


1. Introduction

22/3/00 9:43 AM

Page 6

1.1 Title This code of practice is the Code of Practice: Excavation, 2000. 1.2 Purpose This code provides guidance to prevent injury to persons engaged in excavation work on construction work sites as defined on page 53. 1.3 Scope a. This code covers the planning, preparation and conduct of excavation work. Further information concerning tunnelling is contained in the WorkCover NSW publication Code of Practice: Tunnels under construction. b. This code does not apply to work carried out in a mine within the meaning of the Coal Mines Regulation Act 1982 or the Mines Inspection Act 1901. 1.4 Commencement This code commences on 31 March 2000. 1.5 Authority This code of practice is approved as an industry code of practice pursuant to Section 44A of the Occupational Health and Safety Act 1983, by the Minister for Industrial Relations on the recommendation of the WorkCover Authority of NSW.

2. Planning and preparation

2.1 Consultation The principal contractor, the contractor doing the work, selfemployed persons, employers, employees and their representatives should consult with each other when observing the recommendations of the code and determining the provision of safeguards. The consultation process should be used during the planning and preparation stage to determine safe systems of work based on the assessment of the risk. Structural or geotechnical engineers should be involved in the consultation process when appropriate. The consultation process should at least cover the following: (a) (b) (c) (d) (e) (f)

nature and condition of the ground or working environment nature of work and other activities that may affect safety static and dynamic loads near excavation interaction with other trades workplace access management of surrounding vehicular traffic and ground vibration (g) public safety (h) type of equipment used for excavation work (i) the provision of appropriate amenities, which will depend on the type of workplace. For more information refer to the WorkCover NSW publication Code of Practice: Amenities for construction work 2.2 Planning Planning and preparation is the first essential step in ensuring that work is done safely. Planning and preparation should involve consultation with all relevant persons engaged in the work and should include hazard identification, risk assessment and risk control processes. Where appropriate, the advice of a geotechnical engineer should be sought before starting excavation work. (See Section 3.1.) The OHS Act requires that the principal contractor and contractor in their capacity as employers must: 1. provide such information, instruction, training and supervision as may be necessary to ensure the health and safety of his/her employees; and 2. provide or maintain means of access to and egress from the work place that are safe and without risks. 2.3 Planning by principal contractor The principal contractor, whether as an employer or as the person in control of the workplace, has a statutory duty of care imposed by the OHS Act. This duty is to provide and maintain, in relation to those matters over which he or she has control, a

3

4


22/3/00 9:43 AM

Page 8

workplace that is safe and without risks to health for their employees and other persons present at the workplace or affected by the work. To fulfil these obligations the principal contractor should plan for the work to be done safely. The principal contractor should ensure that a site specific occupational health and safety management plan is prepared and documented for each place of work where construction is to be carried out, before the construction work commences. This plan should be developed in consultation undertaken with the contractor/s and their employees or representatives. The plan should include a documented work method statement, provided by the contractor, describing how the work is to be done safely. The health and safety management plan should be monitored to ensure that work is carried out according to that plan and that the plan is effective. The plan should be maintained and up to date during the course of the construction work. Before excavation work starts, the principal contractor in consultation with the contractor doing the work should at least consider: (a) an assessment of the risks involved in carrying out the work. (See Sections 2.5 and 2.6.) (b) the most appropriate method to prevent any risk of injury. (See Chapter 3.)

(i) electrical safety, including the location of underground and aboveground service cables and nearby overhead power lines and providing systems of work which comply with the recommendations in the Code of Practice: Electrical Practices for Construction Work. (See Section 3.12.) (j) that all persons carrying out the work receive appropriate supervision, training and instruction. (See Chapter 6.) (k) security of excavation during work and when left unattended. (See Section 3.6.) (l) establishment of emergency and rescue procedures in the event of an emergency. (See Section 2.8.) 2.4 Planning by the contractor The contractor doing the work has an obligation under the OHS Act to provide and maintain a workplace that is safe and without risks to health for their employees in relation to those matters over which he or she has control. In addition to consultation with the principal contractor in the overall job planning, the contractor should at least consider: (a) an assessment of the risks in carrying out the work. (b) the most appropriate methods of preventing the risk of injury.

(c) an assessment of the ground conditions and working environment including risks to health and safety from any past contamination by chemicals and/or toxic wastes. (See Chapter 4.)

(c) providing a documented safe work method statement describing how the work is to be done safely. This safe work method statement should take into an assessment of the risk involved in carrying out the work. An example of a safe work method statement is shown at Appendix 3.

(d) providing suitable and safe access to and from the work place including the work area. (See Section 3.14.)

(d) providing suitable and safe access to and from the work area at all times. (See Section 3.14.)

(e) the area of the excavation work is clearly defined by barricades and warning signs.

(e) preventing persons entering a work area where there is a risk of injury.

(f) where necessary the exact location of the work is clearly marked.

(f) an assessment of manual handling tasks which could cause back strains and other injuries and providing systems of work which comply with the provisions of OHS (Manual Handling) Regulation 1991. (See Section 3.13.)

(g) the identification and marking of the location of any above ground, underground or overhead services (eg. gas, water, sewer, electricity, telecommunication cables etc). (See Sections 3.7, 3.12 and Further Information.) (h) that the work does not affect the structural integrity of ading buildings or structures, roads, footpaths. (See Section 3.8.) 5

(g) that the location of overhead and underground services, ie. gas, water, sewer, electricity and telecommunication cables, are identified and clearly marked. (See Sections 3.7 and 3.12.)

6


22/3/00 9:43 AM

Page 10

(h) electrical safety, including the location of underground electrical service cables and nearby overhead power lines and providing systems of work which comply with the recommendations in the Code of Practice: Electrical Practices for Construction Work. (See Section 3.12.) (i) the use of personal protective equipment (PPE) eg. safety footwear, eye, hearing protection, safety helmets, respirators, ultra violet protection, sunscreen, gum boots, disposable clothing etc. (See Chapter 7.) (j) that all persons carrying out the work are provided with appropriate training and instruction. (See Chapter 6.)

2.6 Hierarchy of control measures The following hierarchy of control measures is listed in of levels. Select from the highest level possible to develop each control measure. Level 1: Eliminate the hazard: • For example, choose different construction method. Level 2: Minimise the risk by: • substituting the system of work or plant (with something safer). • modifying the system of work or plant (to make it safer). • isolating the hazard (eg. introduce a restrictive work area). • introducing engineering control (eg. dust control).

(k) that supervision is provided by a competent person. (l) establishment of emergency and rescue procedures in the event of an emergency. (See Section 2.8.)

2.5 Hazard identification, risk assessment and control A hazard identification risk assessment and control process should be carried out by the contractor in consultation with the principal contractor to determine if persons are at risk. Safe systems of work must then be put into place to control the risk. The identification of the hazards associated with excavation work, the risk assessment and the risk control measures should be documented. The process of hazard identification, risk assessment and control is made up of the following steps: 1. Identify the hazards. 2. Assess the risk(s) arising from the hazards. 3. Use appropriate control measures to eliminate or reduce the risk(s). 4. Monitor and review the control measures to ensure continual safety. Appendix 1 shows examples of check lists for some common hazards and risks associated with excavation work and the possible control measures. After identifying the hazards involved in carrying out the work the principal contractor in consultation with the contractor should assess the health and safety risks and determine what type of safeguards or systems of work will be implemented to ensure the health and safety of all persons on site. This should always include eliminating exposure of persons to the hazard. 7

Level 3: Other controls: • adopting istrative controls such as hazard warning signs (eg. “Excavations in progress”) and specific training and work instructions (eg. manual handling). • using personal protective equipment (eg. eye, respiratory and hearing protection). The control measures at Level 1 (eliminate the hazard) give the best results and should be adopted. The measures at Levels 2 (minimise the risk) and 3 (other controls) are less effective and they require more frequent reviews of the hazards and systems of work. In some situations a combination of control measures may need to be used. The control measures recommended by the contractor should be considered by the principal contractor as part of the health and safety management plan. Any new control measures should be evaluated to ensure that they are effective and safe and that new hazards are not created (directly or indirectly) by them. Appendix 2 shows an example of addressing a risk using the above hierarchy of controls. 2.7 Preparation When preparing for the commencement of work the principal contractor and the contractor doing the work should ensure that the workplace is safe based on the health and safety management plan. They should also check to ensure that all controls identified by the risk assessment have been put in place and that no new hazards exist. Preparation should also at least include: (a) an assessment of climatic/environmental conditions. (b) access to and from the workplace. (See Section 3.14.) 8


22/3/00 9:43 AM

Page 12

(c) specific instructions for employees. (See Chapter 6.) (d) that plant and equipment is suitable for the intended use and is properly maintained. (See Chapter 5.)(e) residual current devices (safety switches) protecting the use of portable electric powered tools. (See Section 3.12.) (f) personal protective equipment. (See Chapter 7.) (g) that the location of underground, above ground and overhead services are identified and clearly marked. (See Sections 3.7 and 3.12.) (h) emergency and rescue procedures in the event of an accident, injury or other emergency, including the means of rescuing persons, and arrangements where necessary to protect any other persons in the vicinity. (See following section.) 2.8 Emergency and rescue procedures An employer should ensure that, in the event of an emergency, adequate arrangements have been made to ensure the safety of workers and other persons on site. The emergency may result from an accident or injury, fire, chemical or gas leak, landslip or other potentially dangerous occurrence. Natural disaster including electrical storms, floods, fire etc may also present hazards to the working operations. An employer should plan for such matters and ensure that appropriate control measures are in place. The risk assessment should take into the following factors: (a) (b) (c) (d)

nature of hazard and possible emergencies; size and location of place of work; number and mobility of persons at the workplace; and location of nearest emergency services.

Control measures may include: (a) development and communication of a warning system. (b) development and communication of safe and rapid evacuation procedures, including injured persons. (c) having trained personnel to oversee evacuation and rescue procedures until emergency authorities arrive. (d) appropriate medical treatment and evacuation of injured persons. (e) shutting down of work, including plant and electrical equipment. (f) provision of firefighting and rescue equipment at appropriate locations. (g) display of evacuation procedures in appropriate location(s) at work site. 9

3. Work systems and control measures

The principal contractor and contractor have an obligation under the OHS Act to provide and maintain a workplace that is safe and without risks to health for their employees in relation to those matters over which they have control. Control measures to prevent persons being injured during excavation work must be provided and maintained as part of a safe system of work. (See Sections 2.5 and 2.6.) The system of work and control measures selected are generally determined by individual job factors identified in the consultation and risk assessment process. (See Chapter 2.) The following hazards are commonly associated with excavation work and should be considered by the risk assessment process: (a) (b) (c) (d) (e) (f) (g) (h) (i) (j) (k) (l)

the fall or dislodgement of earth and rock the instability of the excavation or any ading structure the inrush or seepage of water unplanned with utility services eg, electricity cables and gas main the placement of excavated material falls into excavations the movement and positioning of heavy plant and equipment affecting the excavation ground vibration affecting the stability of the excavation vehicle movement excessive noise from the operation of machinery and plant manual handling injuries changes to excavation conditions.

3.1 Prevention of collapse or failure of trenches and open excavations Injuries resulting from collapse of trenches and excavations have occurred in the past as a result of the inability of the soil to stand by itself for the duration of the work and as a result of decisions taken by persons with insufficient expertise in the area of soil stability. A risk assessment should be conducted to determine which controls will be implemented to prevent persons being injured by collapse or failure of all or part of a trench or open excavation. It should consider at least the following: (a) the depth of the excavation; (b) the nature of the strata - sand, clay, shale, floaters, etc including their likely behaviour upon exposure to the elements; (c) fractures or faults in rock. 10


22/3/00 9:43 AM

Page 14

(d) the presence of moisture or water; (e) the possibility of exposure to wet weather and water from other sources; (f) any load close to the edge or in the zone of influence of the excavation; (g) vibration; (h) the exposure time; (i) any previous disturbance of the ground, eg previous excavations; and (j) ading buildings or structures. Some of the common excavation wall failures are shown in Figure 1.

Water table

Unstable lumps fall into trench

Centre of gravity of soil strip Rotational slip failure

Slump failure of soil mass

Failure through slippage along bedding planes

Fig. 1 Soil failure modes. Removal of soil from an excavation causes unbalanced soil stresses which reduce the capacity of the excavation to itself. Control measures that have worked previously may not be satisfactory for a current situation. There may be additional geotechnical engineering issues that should be considered. Accordingly where the risk assessment identifies the risk of an unstable condition, the following measures should be considered before starting excavation work: (a) seeking advice from appropriately qualified engineers, (b) carrying out a geotechnical analysis, (c) engaging a competent person to supervise the progress of the excavation work. Shoring systems, benching and battering are engineering issues that involve both structural design and soil mechanics. The use of adequate shoring, benching and battering is essential to control the risk of a collapse or failure of a trench or open excavation. (See Sections 3.2 - 3.5.) 11

3.2 Design of engineering controls Design specifications for engineering controls such as shoring structures, benching or battering should be prepared by an appropriately qualified person in accordance with relevant standards and codes. In developing specifications, at least the following factors should be considered: (a) the size and strength of the component of the shoring (b) existing and changing ground conditions (c) the loads and types of ground or soil conditions to be shored (d) static loads near excavation, eg. spoil pile, buildings and structures (e) dynamic loads near excavation, eg. traffic and excavation equipment (f) ground vibration, eg. heavy traffic, mobile plant, trains, pile driving and blasting. (g) undermining of roads, footpaths, buildings, structures etc (h) difficulties or risks that other services may pose ie overhead power lines, existing or proposed under ground services (i) working environment such as exposure to dust, fumes, gases, noise, water, contaminated atmosphere or ground etc (j) that systems of work are in accordance with any requirements of the local council, NSW Police Service and Environment Protection Authority (EPA) (k) location of utility services (l) safety during installation and removal. 3.3 Shoring It is a legal requirement that where necessary, all trenches and excavations must be adequately shored or ed to prevent a fall or dislodgement of earth, rock or other material forming the side of or adjacent to, any excavation work from burying, trapping or striking a person that is in the excavation. Where such a risk also exists for those installing s, other appropriate control measures must be in place to ensure the safety of persons entering the excavation. A shoring system is not required if, having regard to the nature and slope of the side of the excavation and other relevant circumstances there is no reasonable likelihood that earth, rock or other material will fall or dislodge from a height of more than 1.5m and bury, trap or strike a person that is in the excavation. The risk assessment process should be used to identify unstable conditions and the risks involved. Shoring the face of an excavation should proceed as the work of excavation progresses. Where a mechanical digger is used, the risk assessment should be used to determine whether any part of the trench may be left uned. Shoring may include any suitable system of temporary s and sheeting material used to maintain the stability of the sides of an excavation. The installation and removal of shoring should take place from outside an excavation. 12


22/3/00 9:43 AM

Page 16

Types of shoring and systems include, but are not limited to: (a) sacrificial sets - stay in the ground indefinitely, may be timber, concrete etc. (b) soldier sets - timber, steel proprietary (c) full timber systems (d) trench s (eg. shields, boxes or cages etc) (e) sheet piling (f) precast s (g) diaphragm walls (h) rock bolts and ground anchors (i) caissons (j) sand bag (sand cement mix) (k) hydraulic systems (l) soil nails, shotcrete, etc (m)pneumatic systems.

Runners Extended to one metre above excavation for fall protection

These and/or other types of appropriate ground equipment should be on site before the excavation work commences. Figure 2 shows some of the common types of earth systems.

2D. Sheet Piling 2C. Full Timber System One Metre High Handrail System

2B. Precast s

2A. Soldier sets - Timber Steel, proprietory

2E. Trench Shields 2F. Rock Bolts Figure 2

Examples of Shoring Figure 2

13

14


22/3/00 9:43 AM

Page 18

3.3.1 Removal of shoring s

When removing shoring, the system should be extracted / dismantled in the reverse order of its installation. Persons performing the work in the excavation should not work outside the protection of the ground system. 3.4 Benching and battering excavation walls Both benching and battering of excavation walls are methods of work which minimise the risk of the soil or rock slipping onto the excavation.

Combination of benching and battering

Figure 3c

Benching is the creation of stepped sides to an excavation. This is done by forming a series of vertical and horizontal planes forming a number of steps in the wall of an excavation. (See Figure 3a.) Benching is used to reduce the height of the vertical wall of an excavation by cutting a series of steps. A risk assessment should be conducted to determine the height and width of the steps necessary to ensure stability.

3.5 Inspection of systems It is a legal requirement that excavation work must be examined prior to commencement of work and at regular intervals to ensure that the excavation and its ing systems are stable and intact to ensure the safety of work proceeding. The risk assessment should determine the intervals of inspection. Inspections should be conducted and documented by a competent person.

A batter is where the wall of an excavation is sloped back to a predetermined angle. Battering should commence from the bottom of the excavation. (See Figure 3b.)

Where risks or hazards that create a risk to health and safety of those carrying out the work are identified, they must be controlled prior to any further work being carried out. This may require further advice from geotechnical and design engineers to review the adequacy of the control measures in place. (See Sections 3.1 and 3.2.) The risk assessment should be reviewed after collapses or falls of materials, after adverse weather conditions and after use of explosives.

When benching or battering the walls of an excavation, an angle of repose of 45 degrees should not be exceeded unless certified in writing by a geotechnical engineer.

The following conditions should be considered or monitored: (a) (b) (c) (d) (e) Benching

Battering

Figure 3a

Figure 3b

In some circumstances, it may be appropriate to use a combination of the two methods on an excavation. (See Figure 3c.)

15

shoring becoming unstable shoring components not secure or failing angle of batter remains sufficient to prevent collapse premature removal of shoring workers in excavations venturing outside the confines of shoring, benching or battering (f) cracks appearing near the edge of an excavation (g) excavated and other material being placed within the zone of influence of the excavation (See Section 3.10.) (h) machinery operating within the zone of influence of excavations causing weight and vibration influences (See Section 3.10.) (i) surface soil falling into the excavation (j) water seeping into excavations from its side walls or base (k) changes to soil and/or weather conditions (l) extra loading (m)surface water or run-off entering the excavations or accumulating on surface near the excavation (n) inclined bedding planes “dipping” into the excavation (o) heaving or swelling of the ground at the bottom of the trench (p) subsidence alongside the excavations (q) unsafe access or egress (See Section 3.14.) 16


22/3/00 9:43 AM

Page 20

(r) fumes, gases, asbestos, silica dust or other substances contaminating the work area (See Chapter 4.) (s) exposure of contaminated ground (See Chapter 4.) (t) undercutting of the excavation Excavations such as parallel and nearby excavations that are within the zone of influence of each other have weakening effects on each other’s walls. The relatively thin wall of undisturbed material that may separate two excavations may be under increased side pressure and therefore more likely to collapse.

(b) removal or lowering ladders on work site (c) immobilisation of plant to prevent unauthorised use (d) compliance with relevant local authority requirements (police, council, fire brigade) (e) hazard warning lights, signs, markers or flags (f) sentries (may be necessary to provide protection for the public and employees) (g) site security measures, including fencing or use of safety observer(s) (h) night lighting.

Similar hazards exist when excavating near old excavations that have not been backfilled; particularly if the old excavation is waterlogged or its fill has not consolidated.

Signs should be erected around the site showing the name and telephone number (including after hours emergency number) of the principal contractor/contractor.

A risk assessment should be used to identify any particular risks arising from working near disturbed or previously excavated ground and appropriate controls should be implemented. When working near disturbed ground, the risk assessment should consider the capacity of shoring to resist any additional pressures. It may be necessary to seek advice from an appropriately qualified geotechnical engineer to ascertain types and strengths of any additional pressures.

3.6.1 Fall prevention A safe system of work and appropriate control measures must be provided wherever persons are exposed to a risk of falling during excavation work. It is a legal requirement to effectively fence all excavations and holes more than 1.5m deep. It should also be noted that all platforms, open sides of stairways and stairway landings must be fenced.

3.6 Security of excavations Many accidents on construction or demolition sites have involved people including young children sustaining serious injuries as a result of inadequate control measures being in place to prevent uncontrolled entry to the site. These injuries include falls into open excavations, injuries as a result of plant not being immobilised and people being struck by falling objects. Even shallow excavations can be trip and fall hazards. The OHS Act obligation to ensure a safe workplace extends to others present at the workplace or affected by the work, including contractors, visitors, delivery drivers, etc. A risk assessment should be conducted in order to determine which controls will be implemented to ensure the security of excavation both during work and when left unattended. The control measures implemented must be appropriate and effective for the hazards and risks of the situation. Consideration should be given to factors such as how long the excavation will be open, and who may gain access to the excavation (all persons, including pedestrians, children), etc. The following control measures should be considered: (a) isolating the hazardous area, such as by the use of perimeter fencing, barricades, screens, barriers, handrails and/or covers, which are capable of preventing access or preventing the fall of a person 17

In addition to the security measures listed above, the following measures to prevent falls should be considered: (a) pedestrian detours, which should be clearly defined and protected (b) use of intermediate platforms for deep excavation (See Section 3.14.) (c) provision of a safe means of movement between different levels of the excavation (See Section 3.14.) (d) provision of an adequate fall arrest system (e) backfilling as work progresses (See following section.) Control measures should be properly installed and maintained until the work is completed or until there is no longer any risk of persons falling into the excavation. 3.6.2 Backfilling procedures The risk assessment should be used to determine whether backfilling should be performed both as the work progresses and at the end of the day’s work in order to reduce the hazard. Backfilling has the following advantages: (a) reduces the implementation and maintenance of other safeguards over a larger distance/area (b) eliminates the fall hazard (c) assists control of the job by restricting the work area (d) provides alternative means of access and egress into the excavation, rather than by ladders 18


22/3/00 9:43 AM

Page 22

(e) provides an alternative to the use of fences and handrails. Backfilling reduces the exposure to risks such as collapse or falls by eliminating the hazard. Backfilling should be considered for use during the progress of pipe laying work. A risk assessment should be used to determine the length of pipe left exposed both during work and when work is discontinued for any time. (See Figure 4.) Note: where compaction work is to be undertaken the additional hazards of fumes and effects of vibration should be considered.

End shield

Shield extended one metre to provide fall protection Direction of work for mp s Ra cces A

Shield

Ground Level

Pipe

3.7 Underground services Before starting the work, the location of any underground services (eg. gas, water, sewer, electricity, telecommunication cables, etc) should be identified. When gas pipes are cut or punctured, friction can cause a spark resulting in an explosion. Gas authorities are able to blow pipes clear to make them safe. (See Further Information.) Wherever service plans are available they should be obtained by the principal contractor and also provided to the contractor and operator carrying out the excavation work. The contractor carrying out the work should allow for inaccuracies and the possibility of other unknown or hidden services. This may be assisted by hand digging or allocating a spotter to search for services when strata changes occur. Further, the principal contractor should arrange for these services to be clearly marked according to the available plans and on site checks prior to commencement of work. Services should be exposed at sufficient intervals to positively identify their location and/or lie. The following are ways of checking for underground services: (a) ing organisations that can assist in locating underground services such as those mentioned in the Further Information section. (b) using remote location devices (c) using gas detectors (d) hand digging, using hand tools with non-conductive handles.

Dig and Lay System of Work

Figure 4 3.6.3 Prevention of drowning Where, during excavation work, and excavation is likely to collect or retain water so as to create a hazard to persons in the vicinity (including children), the excavation should be covered or fenced off. Control measures must be provided where there is a risk of a person drowning as a result of a fall into water or other liquid, eg slurry. The following measures should be considered: (a) provision of positive means of fall protection such as fencing, handrails and safety harness (b) provision of flotation vests (c) provision of rescue means such as lifebuoys or rescue boats (d) provision of an observer. Consideration should also be given to ensuring the availability of qualified personnel to ister expired air resuscitation in the event of an accident and the prominent display of a cardiopulmonary resuscitation (R) chart. 19

All persons whose work may be affected by an underground service should be advised of the location of every underground service. (See Chapter 6.) Appropriate control measures should be implemented after consultation with relevant service providers. These measures may include the protection, or removal of services to ensure safety of workers. For further information on underground electrical hazards see Section 3.12.1. 3.8 Excavations adjacent to buildings or structures It is a legal requirement that employers ensure that excavation work which is likely to reduce the security or stability of any part of any building or structure must not be commenced or continued unless adequate steps are taken before and during the progress of the work to prevent danger to any person from collapse of the building or structure or a part of a building or structure. In assessing the risk, measures such as the following should be considered before starting excavation work: (a) seeking advice from appropriately qualified engineers (b) undertaking a geotechnical analysis 20


22/3/00 9:43 AM

Page 24

(c) engaging a competent person to supervise the progress of the excavation work (d) underpinning of structures (e) construction of effective retaining walls (f) minimising ground disturbance and vibration by taking into the location of machinery, the sequence of work, the impact, severity and scale of excavation (g) backfilling as work progresses (h) evacuation of affected areas. The contractor should also ensure the stability of pedestrian or vehicular access which might be affected by the work. 3.9 Protection against rising, irruption or inrush of water or material It is a legal requirement that employers ensure that where there is risk from rising water or from an irruption of water or material, the means to enable every person to reach a position of safety must be provided.

To reduce the risk of excavation collapse, excavated or other loose material should be effectively stored or retained away from the excavation. Excavated material should be placed outside the zone of influence. Alternatively the system should be designed to accommodate such additional loads including ground water pressures, saturated soil conditions and saturated materials. Mechanical plant, vehicles, storage of materials or any heavy loads should be prevented from approaching within or encroaching on the zone of influence of an excavation unless the system has been specifically designed for such loads. (See Figure 5.) Where the risk assessment has identified a risk of collapse as a result of loads or materials above or near the excavation, shoring must be in place before any person enters the excavation.

Should a risk assessment reveal a risk of rising, irruption or inrush of water or material, appropriate control measures must be provided. These may include the following: (a) implement isolating procedures such as physical or mechanical barriers, provision of suitable valves, etc to isolate the supply (b) provision of membranes to prevent the rising or inrush of water (c) provision of exploratory or warning holes where water flows at a reduced rate to warn of danger (d) provision of sumps (e) lowering the water table (eg use of spear pumps) (f) freezing the ground (g) increasing exit points eg increasing the number of exit ladders (h) provision of suitable life-saving equipment eg lifelines and buoyancy vests (i) provision of pumps (j) an effective emergency rescue plan (See Section 2.8). 3.10 Materials and loads above and near excavations It is a legal requirement that employers must ensure that materials are not placed or stacked near the edge of any excavation work so as to endanger persons employed below. It is a further requirement that no load be placed or moved near the edge of any excavation work where it is likely to cause a collapse of the side of the excavation work and thereby endanger any person. 21

22


22/3/00 9:43 AM

Page 26

The following measures should also be considered before starting excavation work: (a) controlling access to exclude persons from hazardous areas, eg relocating means of access (b) moving and storing loads outside the zone of influence of the excavation (c) adopting a system of dig and lay to reduce the risk of overloading from pipes stores near the excavation (d) provision of wheel stoppers to limit movement of mobile equipment adjacent to the excavation (e) reducing the number of trench shields stored near excavation by pulling along trench shields and backfilling as the excavation progresses (f) securing all loose materials in place, including stored pipes.

5a. Shoring designed for surcharge loads

5b. Shoring designed for soil loads only

When working on a slope, a risk assessment should be conducted to determine the safest side of the excavation to dump soil and excavated material. This would often be on the lower side of the slope to reduce the risk of wall collapse or material falling into the excavation. Site factors would have to be considered. (See Figure 5d.) There are also risks in backfilling on sloping sites. For more information about working on sloping sites see the WorkCover NSW publication A guide for front end loader and excavator drivers. 3.11 Protection from falling objects It is a legal requirement that employers must provide overhead protection, wherever practicable, where there is a likelihood of persons being injured by falling objects. Tools, materials and equipment can fall from ladders, scaffolding, cranes and work platforms.

Wheel Stopper

5c. Limiting approach of equipment

5d. Spoil altering depth of trench

Machinery and loads near excavations

Figure 5

23

The risk assessment should be used to determine appropriate control measures to protect persons from accidental falls of objects including tools, plant and other construction materials. As far as practicable, loads should not be suspended or travel over a person. The following control measures should be considered: (a) fences (b) hand rails and toe boards (c) overhead protection (d) enclosed walkways (e) safety helmets and other adequate means of protection (f) provision of safe means of lowering and raising plant, materials, spoil, etc (g) use of lanyards to secure loose tools (h) loads should be lifted/suspended within the safe working limits of the machinery load used. The risk of injury from falling or displaced objects increases during high winds. Practical guidance on the design, supply, installation and use of overhead protective structures is found in the WorkCover NSW publication Code of practice: Overhead protective structures. 24


22/3/00 9:43 AM

Page 28

3.12 Electrical hazards Live powerlines (whether overhead or underground) are a major hazard, particularly in excavation, and have caused a number of fatalities. In addition to direct electric shock and possible electrocution, with overhead powerlines in particular can lead to a variety of hazardous conditions including fire, unpredictable cable whiplash and the electrifying of other objects eg signs, poles, trees or branches. Specific control measures must be implemented when work is done in the vicinity of powerlines whether they are overhead or underground. A power line or electrical conductor should always be assumed to be energised or ‘live’, including when a communication cable or wire is encountered. 3.12.1 Underground electrical hazards

A safe system of work must be devised to address electrical hazards associated with underground services. This should take into consideration the recommendations outlined in Section 3.7 as well as the following: (a) de-energising and isolating the cables and obtaining documentary evidence of the continuing isolation of the power supply before proceeding with the work (b) a system of lock out and lock out tags (c) use of electronic surveillance prior to excavation to determine location of services. (d) hand digging using tools with non conductive handles (e) wearing rubber boots and insulating gloves complying with AS2225:1994 - Insulating gloves for electrical purposes. 3.12.2 Overhead power lines

Plant that comes into with an overhead or underground cable may become electrified and pose a serious danger to the operator and any bystanders. Where work has to be carried out near live powerlines, conductors or electrical apparatus, the type of cable and operating voltage should be identified. It is a legal requirement that when cranes, excavators, earthmoving machines or similar appliances are operated near overhead power lines the following provisions must be observed: (a) A thorough examination of the approaches and surroundings of the site must be carried out before taking an appliance to the site or setting it up. This examination is to determine whether precautions need to be taken to prevent any part of the appliance, any load carried on it and 25

any person on it coming into with or being within the following distances to overhead power lines: Voltage up to 132 000 more than 132 000 but not more than 330 000 more than 330 000

Distance 3 metres 6 metres 8 metres

In calculating these distances the following should be considered: • the sag of the cables; • the swing of the load during handling; and • the effect of wind forces. (b) if the risk assessment indicates a possibility that these distances may not be maintained during carrying out the work, then consideration should be given to an alternative way of doing the work which eliminates the risk of . (c) A person other than the driver or operator of the appliance must be present to observe the position of the appliance and to warn the driver or operator of the nearness of the overhead power lines. The following measures should also be considered: (a) eliminating the hazard by using an alternative plant which cannot encroach on these distances (b) de-energising and isolating the supply and obtaining documentary evidence of the continuing isolation of the power supply before proceeding with the work (c) setting up the appliance in a position that eliminates or minimises the hazard (d) placement of appropriate warning signs at approaches to powerlines at distances to be determined by a risk assessment (e) mechanically limiting the hoisting, slewing or other movements of the appliance (f) providing ground barriers to limit the travel of the appliance (g) using properly maintained non conducting taglines to control the load (h) insulating the conductors. Overhead power line insulating covers such as tiger tails may be used but are generally only suitable for brush . It is a legal requirement that appliances used near overhead power lines must have a permanently affixed Electrical Hazards warning notice. A sample of this notice is shown in Figure 6:

26


22/3/00 9:43 AM

Page 30

•

DANGER BEWARE OF OVERHEAD ELECTRICAL HAZARDS REGULATION 133A OF THE CONSTRUCTION SAFETY ACT 1912 REQUIRES a.

Minimum approach of an appliance to live electrical apparatus

b.

Inspection of the work site for electrical hazards before commencing to use the appliance

c.

Constant vigilance and an observer required whilst working or travelling the appliance in the vicinity of live electrical apparatus

{

3m for voltages up to 132, 000 6m for voltages above 132, 000 and up to 330, 000 8m for voltages above 330, 000

Figure 6 3.13 Manual Handling The OHS (Manual Handling) regulation 1991 requires employers to design equipment, tasks and work environments so that manual handling risks are eliminated or reduced as far as reasonably practicable. Employers must assess and control the risks involved in carrying out manual handling tasks. This must be done in consultation with employees who are required to carry out the work. Guidance on identifying, assessing and controlling manual handling risks can be found in the Worksafe National Standard and Code of Practice for Manual Handling. The following practical guidance outlines some ways in which manual handling risks can be controlled. However, employers are still required to undertake their own risk assessments and implement control measures. This should be included in the safe work method statement which describes the sequence of work tasks and activities and how the work is to be done safely. Where the nature of the work activities or manual handling tasks are constantly changing, the risk assessment and control process and training should be conducted on an ongoing basis The employer should control risks by: (a) deg or re-deg the manual handling task to eliminate or control the risk factor. Where re-design is not practicable, the employer should: •

provide mechanical aids and/or personal protective equipment. Using powered mechanical equipment to lift and move materials may control manual handling risks. Lifting equipment could include cranes, forklifts, electric pallet trucks and stackers. 27

•

introduce mechanised systems of work to eliminate or reduce manual handling. Many trucks and utility vehicles have ramps or hoists for loading and unloading heavy equipment. There are also many different types of trolleys available. These can be useful for moving heavy and awkward loads such as large drums. arrange for team lifting in order to reduce the risk. Team lifting (sharing the load between 2 or more employees) should be used for loading, unloading, stacking and moving frames and other large items where it is impractical to use mechanical assistance. Employees should be encouraged to ask workmates for help if something is too heavy, too large or too long to handle alone. They should never lift or move anything that is too heavy or awkward for them.

(b) providing appropriate training to employees in safe handling techniques. This training should also include the prevention of manual handling injuries by an approach based on a hazard identification, risk assessment and control through job and task design. Employees should receive appropriate training in methods of manual handling involving team lifting procedures, correct use of the mechanical aids and PPE. (c) weights that are manually handled should be minimised. The Worksafe National Standard and Code of Practice for Manual Handling advises caution where loads are above 16-20 kg. Furthermore persons should not be required to lift, lower or carry loads above 55kg, unless mechanical assistance and/or team lifting arrangements are provided to lower the risk of injury. Many supplies can be ordered in smaller loads (such as 20kg bags of cement etc). (d) where manual handling involves repetitive bending, twisting, over-reaching, work overhead or where persons have preexisting injuries, these loads should be further decreased. Often used items such as tools, drums of chemicals etc, could be stored at waist level and taps installed so chemicals can be dispensed without lifting the drum. Where possible, ensurethe most commonly used items are stored between thigh and chest height. (e) manual double handling may be reduced or eliminated by delivering materials as near to the work location as possible. (f) the rotation of work duties should be considered in consultation with employees so that employees are not subjected to the same task for the whole shift. (g) ensuring that work areas and ageways are kept clean and clear of debris. Slippery floors and surfaces and trip hazards are common and can be easily controlled. 28


22/3/00 9:43 AM

Page 32

3.14 Access The OHS Act requires that a safe means of access must be provided and maintained to every place at which any person has to work at any time. Slips, trips and falls are common accidents at work and may cause serious injury. Safe access includes considering a number of factors including lighting, ramps, walkways, scaffolding and ladders. Consideration must also be given to controlling the risks to visitors, contractors, drivers and other people coming into the work site. Access hazards include wet or oily floors or surfaces, untidy work areas, cluttered ageways, steep or slippery steps and stairs, exposure to plant and poorly lit work areas. An assessment of access requirements should take into the number of persons using them and any tools and equipment that they may be required to carry to and from the work site. Control measures may include: (a) proper storage of materials and plant (b) keeping work areas and ageways clear and free of obstructions (c) removal of rubbish, including construction waste and excess excavated material (d) use of handrails (e) traffic and plant controls (f) safety fences and warning signs. Also refer to Sections 3.6 (Security of excavations) and 3.6.1 (Fall prevention) of this code. For more information, refer to the WorkCover NSW publication Preventing slips, trips and falls guidance note. 3.14.1 Lighting

It is a legal requirement that adequate lighting (natural or artificial) must be provided to ensure the work areas and access ways are well lit. Adequate local lighting must be provided for detailed work, for dangerous processes and where machinery is being operated. If artificial lighting is used, including lighting for night work, ensure it does not create excessive glare or shadows. Sufficient lighting (eg battery powered) should be installed in stairways and ageways to allow safe access to and from all areas if there is insufficient natural light. A risk assessment should also consider lighting of evacuation routes and emergency exits. 29

3.14.2 Ramps

Where access ramps are provided they should not exceed 1: 2.7 (20 degrees). Ramps steeper than 1:8 (7 degrees) should be cleated, grated or have surfaces which allow adequate foot grip. Where such ramps form part of an excavation, a risk assessment should be conducted to determine the maximum safe soil height above the ramp before some sort of soil (eg trench shield) is provided. (See Figure 4.) Ramps should be designed and constructed to effectively withstand any anticipated load that they may be required to during use. 3.14.3 Ladders

Where ladders are used for access it is a legal requirement that employers must provide the following: (a) the ladder must be secured at both top and bottom against displacement. Ladders should have non-slip feet and whenever practicable must be set up at an angle of 1:4 (75 degrees). (b) a safe and adequately sized landing place when stepping off the ladder must be provided. (c) the stiles of the ladder must extend at least one metre above the landing place. (d) metal or wire reinforced ladders must not be used where there is a risk of with electrical conductor wires (powerlines) or of electric shock. Non-conducting ladders should be used or a clearance of at least 4 metres from conductors should be maintained. 3.14.4 Scaffolding

Scaffolding may be used to provide workers with a safe temporary work platform. It is a legal requirement that scaffolding must be erected in accordance with AS/NZS 1576:1995 - Scaffolding. It should be planned, erected and inspected by competent persons and should be regularly inspected to ensure there are no risks to safety. 3.14.5 Fixed platforms, walkways, stairways and ladders

It is legal requirement that fixed platforms, walkways, stairways and ladders must comply with the requirements of AS1657:1992 - Fixed Platforms, Walkways, Stairways and Ladders - Design, construction and installation. 3.15 Work near traffic or moving plant Carrying out work near moving plant or vehicular traffic is often a high-risk activity where additional control measures are necessary to ensure workplace health and safety in relation to the use of the plant and activities around them. 30


22/3/00 9:43 AM

Page 34

For guidance regarding the common hazards associated with work near moving plant on construction sites as well as recommendations for assessing and controlling the risks involved refer to the WorkCover NSW publication Safety Guide: Moving plant on construction sites. At times construction work may be carried out near moving plant on greenfield construction sites as well as on or near public roads and pedestrians. Further guidance and information regarding carrying out construction and maintenance work on public roads, in a way that promotes the safety of both road s and workers on site, is contained in the series of standards AS1742 - Manual of uniform traffic control devices. AS1742.3:1996 - Traffic control devices for works on roads contains specific guidance relating to work near or on public roads and traffic. These Standards are ed by a series of field guides - SAA HB81: Field guide for traffic control at works on roads. Guidance and information regarding the selection, design and implementation of public road traffic control plans are contained in the 1998 Roads and Traffic Authority Manual: Traffic control at worksites. Planning and preparation should also include the development of a vehicle movement procedure for each worksite. Vehicle movement procedures should identify the preferred travel paths for vehicles associated with a work site entering, leaving or crossing the through traffic stream. A vehicle movement procedure should include persons, moving equipment, plant and vehicle traffic in the work area and also identify travel paths for trucks at key points on routes remote from the work site, such as places to turn around, accesses, ramps and side roads. A vehicle movement procedure may be a documented procedure, a diagram, combined with or superimposed on a Traffic Control Plan, or may be verbal information and instructions specific to the particular construction workplace or site. The risk management process should be used to determine which is the most appropriate. Where work is carried out on public roads vehicle movement procedures should be developed in accordance with AS1742.3:1996 - Manual of uniform traffic control devices Traffic control devices for works on roads. Where work is to be carried out using moving plant, the tasks to be performed should be carefully planned before carrying out any work. (See Chapter 2.) The principal contractor in consultation with the contractor should determine the control measures that will be implemented to ensure the safety of workers and all other persons on the work site. A system of work should be implemented to ensure that no persons are at risk when working near or with moving plant. 31

A risk assessment should be conducted to determine what type of safeguards or systems of work will be implemented on the site and should include eliminating exposure of persons to moving plant. Vehicle movement procedures should be developed based on the risk assessment and should be developed each time the conditions on the site change in a way that may effect the health and safety of persons. The risk assessment should consider at least the following: (a) isolating vehicles and plant used in or around the site and work area from persons on the site or work area, eg vehicles or persons may be guided around or past the work area. (b) securing the area where moving plant is being used eg fencing, barriers, barricades, temporary warning or control signs or a combination. (c) planning the direction that the plant moves so that the visibility of operators is not restricted. This should also include an assessment of the visibility of plant and traffic from all areas of the work site. (d) the use of spotters/safety observers to control traffic movement (e) persons working on public roads should be trained in accordance with AS 1742. (f) implementing safe working distances (g) the use of audible reversing alarms and/or other technologies or other safe work practices. Note: reversing alarms may cause confusion where multiple plant is using the same area and other systems of work may be required. (h) minimising the number of moving plant working at one time. Where multiple plant is being operated around the work site a competent person should be used to direct the plant: • when operating in close proximity to each other; • when reversing; • where persons are on the ground; and • in other situations as indicated by the risk assessment. (i) where construction vehicles or plant enter or leave the work area by public roads, systems of control and notices should be placed at all entrances and exits to the work area to protect and warn all persons approaching or in the vicinity (j) where plant is being operated near persons, near underground or above ground services (any other workers, soils technicians, surveyors, visitors etc) (k) designated delivery and turning areas. The movement of delivery vehicles on construction sites frequently presents a hazard particularly when reversing, loading and unloading. 32


22/3/00 9:43 AM

Page 36

Procedures should be implemented to warn all persons affected by the potential hazard. These procedures should include: • the requirement for truck drivers to report to a suitably signposted area on the site; • the requirement for a designated worker to act as an observer to ensure all persons are clear of the reversing vehicle; and • a system of communication and warning to persons near delivery point. All personnel on site should wear high visibility garments. These garments should be selected, used and maintained in accordance with AS/NZS4602:1999 - High Visibility Safety Garments. 3.16 Noise Noise management provisions should be carried out by the contractor doing the work and must ensure compliance with OHS (Noise) Regulation 1996 so that noise levels from machinery or equipment being used do not become a risk to hearing or health. The noise management provisions in the WorkCover NSW publication Code of practice for noise management and protection of hearing at work are a practical guide on managing noise levels at the workplace.

3.17 Fire protection The risk of fire is associated with activities that may generate explosive gases or dusts, or where flammable substances, combustible dusts or waste materials are stored. Potential ignition sources include naked flames, hot plant, electrical equipment, static electricity, friction and welding equipment. A risk assessment should be conducted to identify potential fire risks and appropriate control measures should be introduced. These may include: (a) identification and control of potential ignition sources (b) removal of waste and other combustible material (c) effective storage of flammable substances, including explosives, with adequate signage to notify the hazard (d) continuous monitoring of workplace (e) establishment of fire emergency procedures, including warning and evacuation systems (f) provision of suitable, sufficient and appropriately located fire fighting equipment to ensure that all persons are protected in the event of fire. Also see Section 2.8 - Emergency and rescue procedures.

The risk of causing permanent hearing damage is related to both loudness of the noise and the length of exposure. For example two minutes working in noise levels of 114 decibels dB(A) may have the same effect as eight hours of working in 85 dB(A). An appropriately qualified person should conduct a noise assessment to determine the level of noise that employees are exposed to. Where the noise is in excess of the noise exposure limits, engineering controls should be implemented. Where this cannot be achieved or work cannot be organised to minimise exposure, appropriate hearing protection equipment, which complies with AS 1270:1988 - Acoustics - Hearing protectors, should be provided to all persons in the vicinity of the noise. The contractor should also ensure compliance with Environmental Protection Authority requirements in relation to noise. For more information assessing noise levels see the WorkCover NSW publication ‘Do I have a noise problem?’. 33

34


4. Protection against contaminated environments

22/3/00 9:43 AM

Page 38

4.1 Protection against airborne and soil contaminants People may be exposed to contaminants through inhalation (breathing), ingestion (swallowing) or absorption (eg through the skin or eyes). Materials that can present a physical, chemical and/or biological risk to human health include some forms of metals (such as lead, cium and mercury); toxic elements and compounds; hydrocarbons and chlorinated hydrocarbons; pesticides; toxic, explosive and asphyxiant gases; combustible substances; biologically active substances and microorganisms; hazardous wastes; radioactive wastes and other material such as asbestos, synthetic mineral fibres and silica dust. Contractors must ensure that all necessary prevention or protection measures are taken to ensure the health and safety of persons who may be exposed to excavated material containing a contaminant. Where there is a risk of inhalation of harmful airborne substances such as silica dust or with harmful soil contaminants, the contractor doing the work must ensure a safe system of work including compliance with the provisions of the OHS (Hazardous Substances) Regulation 1996. This regulation requires that employers must ensure that exposure to an airborne concentration of a contaminant classified as a hazardous substance is not at a level greater than that established by Worksafe’s ‘Exposure standards for atmospheric contaminants in the occupational environment’. For more information on properly assessing relevant workplace risks refer to the Worksafe Guidance Note for the Assessment of Health Risks Arising from the Use of Hazardous Substances in the Workplace. The risk assessment process (see Section 2.5) should be used to determine the engineering controls, work practices and site, atmospheric or biological monitoring required. Monitoring measures the amount that employees may be exposed to any contaminants or hazardous substances and may be needed as a part of the risk assessment or to check that control measures are effective. Monitoring of airborne contaminants such as dust and fumes involves taking air samples and checking against the standard allowed. Appropriate assessment of the exposure levels should be undertaken before selecting the control measures. Such exposure of workers to chemical, biological and radiological hazards may arise due to contamination of the ground, air or water on site. 35

The assessments should consider: (a) any persons on site, including other contractors or persons working on the site; (b) persons conducting the assessment and site remediation, including subcontract workers; (c) visitors to the site (for example, couriers); and (d) site neighbours (as appropriate). Soil samples should be taken from any site which at any time has stored or is suspected to have stored contaminant, or where a contaminant has been used. Soil samples should be taken at the appropriate depths and spacings so as to positively locate and identify any contaminant that may be present. Soil samples should be tested by an appropriately qualified, trained and/or experienced person. Where contaminated materials are found to be present, specific measures for protection, handling and removal should be taken. Some of these contaminants may be hazardous substances which have exposure standards that must be observed. Details of any exposure standards are set out in the manufacturer’s Material Safety Data Sheet (MSDS). For further information about hazardous substances refer to the WorkCover NSW publication Code of Practice for Control of workplace hazardous substances. For further information on harmful gases, fumes and hazardous substances, see Sections 4.2 - 4.4 of this code. Refer to the Environment Protection Authority for requirements in relation to other work procedures and disposal. The control measures used should be indicated by the risk assessment. The following general control measures relating to harmful airborne substances contained in dust should also be considered: (a) extracting dust at the point of generation and collecting it in such a manner so as not to affect the health and safety of persons at the workplace (b) using water, detergents or other substances to suppress dust at the point of generation (c) using tools fitted with dust extraction or with a water attachment (d) using low pressure water sprays sufficient to suppress dust (e) fitting water applicators onto machinery rather than hand holding them (f) fitting appropriate air filtering systems to the air conditioning units of excavators and other machinery (g) growing vegetation on stockpiles or covering them

36


22/3/00 9:43 AM

Page 40

(h) wetting down muck piles (i) covering loads of trucks removing fill before leaving site (j) spraying water over areas to be ripped and leaving overburden in place when ripping (k) limiting exposures to dust (l) using respirators that are capable of preventing persons inhaling hazardous dust or other airborne contaminants at the concentration and duration of the exposure.

Table 1: Gases commonly found in excavations and trenches

A hazard that is often overlooked on contaminated sites or during the risk assessment is the potential for dust build-up within the cabs of site vehicles, excavation plant and haulage trucks. Cabs should be monitored for dust build-up. Rubber door-seals should be inspected periodically for wear or damage. Vacuum cleaning using High Efficiency Particulate Air filter-equipped machine should be considered. The risk assessment should determine appropriate controls including whether air-filtered cabins on vehicles are required.

Carbon dioxide, methane, hydrogen sulphide Reclaimed land and tip fills

Gases or fumes found

Type of ground

Methane, hydrogen sulphide

Peaty ground and decaying organic matter

Carbon dioxide, hydrogen sulphide

Filled and made ground

Natural gas and carbon dioxide

City streets

Carbon monoxide, carbon dioxide, hydrogen Thermal areas sulphide, sulphur dioxide, methane Petrol fumes, LPG, kerosene

Petroleum installation and service stations

Table 2: Toxic, flammable and asphixiant gases Contractors should also ensure that exposure to nonhazardous substances such as nuisance dust is at a level not greater than that established by these Worksafe exposure standards. In dry conditions, frequent watering, where practicable, or other similar methods should be used to reduce nuisance dust that should not exceed 10mg/m3. For further information refer to the WorkCover NSW publication A guide to dust hazards. Note: Further specific information on silica dust is contained in the WorkCover NSW publication How to prevent silicosis. 4.2 Harmful gases or fumes Excavations, particularly trenches, being below ground are a natural receptacle for all gases and fumes heavier than air. Gases and fumes from unknown sources can seep through the ground, particularly where other work is taking place nearby. These gases may be natural like methane and sulphur dioxide, or they may arise from nearby internal combustion engines (carbon monoxide and carbon dioxide). There may be leakage from liquified petroleum gas (LPG), underground storage, nearby oil pipes, sewers or natural gas pipes. The gases or fumes most likely to be found in various kinds of excavations are set out in Table 1. Note that some of these gases can be toxic, flammable and asphixiant as indicated in Table 2.

37

Gas

Toxic

Methane Hydrogen Sulphide Carbon dioxide Natural gas Carbon Monoxide Sulphur Dioxide Petrol Fumes, LPG Kerosene

✓ ✓ ✓ ✓ ✓ ✓ ✓

Flammable

Asphixiant

✓ ✓

✓

✓ ✓ ✓ ✓

✓ ✓ ✓ ✓

Employers must implement a suitable system of work so as to ensure a safe respirable atmosphere and effective ventilation and must protect persons against the effects of insufficient oxygen, toxic or explosive gases. These may be encountered when carrying out work such as excavations for foundations, bored and drilled pier holes, shafts, drives, pits, etc, in addition to trenches. Where the risk assessment indicates the possibility of air contamination, the work should be examined by competent persons using appropriate detecting equipment and should include air testing for: (a) flammables (b) oxygen deficiency (c) airborne contaminants (d) toxic gases

38


22/3/00 9:43 AM

Page 42

Tests should be carried out before work starts and with continued monitoring throughout the period of work as indicated by a risk assessment. If combustible or explosive gases are suspected, all persons including of the public, must be evacuated from the site and kept away from the area until control measures are implemented and there is no longer any danger. Where a hazardous work area is identified, the area should be secured against unauthorised entry and appropriately signed. For further information see Section 2.8 - Emergency and rescue procedures and Section 3.6 - Security of excavation, of this code. The normal oxygen content of air is 20.9%. It should not be less than 19.5% or more than 23.5%. A safe oxygen level does not however mean that there are no toxic or flammable gases present. It is not sufficient that the atmosphere is free from airborne contaminants or toxic gases before entry. All persons associated with the work area must have confidence, gained from local knowledge and experience that the atmosphere will not change while work is carried out in the work area. If the risk assessment indicates a risk that the atmosphere may alter, then the work area should be continuously monitored while it is occupied by a worker. This can be assisted by the worker wearing a continuous monitoring device. The device should be capable of sounding an alarm if dangerous gas levels or oxygen deficiency develop. Continuous monitoring devices are readily available.

The OHS (Confined Spaces) Regulation 1990 prohibits the use of combustion engines in confined spaces. It is very dangerous to use an internal combustion engine in a confined space or enclosed area. The exhaust fumes from the engine are very poisonous, and rapidly reach dangerous levels. The engine can also very quickly use up the oxygen in the air. This results in workers being overcome by lack of oxygen, or poisoned by the exhaust gases. Fitting a catalytic converter or scrubber to the exhaust system of each internal combustion engine can reduce the build-up of some toxic gases, but this is NOT a solution to the use of internal combustion engines in unventilated areas. Also it is important to note that catalytic converters only operate when the engine is under load and not when idling. Where persons are carrying out work in an enclosed or confined area, which can include trenches, they may be at risk from a build-up of gases (eg heavier than air gases, particularly carbon dioxide), such as exhaust fumes from nearby plant and equipment. Control measures must be implemented to ensure that an adequate level of ventilation is maintained to prevent the build up of gases eg by directing gases to the open air or use of continuous air replacement systems. Extractor fans or appropriate respiratory protective equipment should be provided and used when working in any confined or poorly ventilated areas. The only respirators suitable for confined spaces are airline respirators or self-contained breathing apparatus.

The use of continuous air replacement systems should also be considered. All persons should carry suitable respiratory protection where there is a risk of not maintaining a safe atmosphere.

Further information is contained in AS 2865:1986 - Safe working in a confined space. Hydraulic, electric or air driven machines are recommended for use in confined or poorly ventilated areas.

4.3 Working in confined spaces The OHS (Confined Spaces) Regulation 1990 sets out minimum standards to ensure the safety of persons working in a confined space. It does this by requiring employers to comply with the requirements and procedures set out in AS 2865:1986 - Safe working in a confined space.

4.4 Using hazardous substances safely Employers and self employed people must identify any hazardous substances used at work and access the risk using information in the MSDS and on the label. The contractor doing the work must ensure a safe system of work including complance with the provisions of the OHS (Hazardous Substances) Regulation 1996. If it is necessary to use the hazardous substance they must:

The regulation defines a confined space at a place of work as a space of any volume, which a person may at any time enter or be allowed to enter, and in which: (a) the atmosphere is liable to be contaminated at any time by dust, fumes, mist, vapour, gas or other harmful substances; or (b) the atmosphere is liable at any time to be oxygen deficient, and includes, but is not limited to, the following: • open-topped spaces of more than 1.5 metres in depth, such as pits or degreasers which are not subject to good ventilation; • pipes, sewers, shafts, ducts and similar structures. 39

(a) prevent exposure beyond the standard exposure limits (b) train employees in the safe use of the substance and ensure they have access to the manufacturer’s MSDS (c) ensure that any necessary PPE is available and is used (d) ensure that all containers are labelled, especially when a hazardous substance is decanted (e) ensure that all containers are cleaned when empty (f) keep of hazardous substances used and a record of training provided. 40


22/3/00 9:43 AM

Page 44

Some hazardous substances have exposure standards that must be observed. This may be particularly relevant for substances that are applied as a spray. Details of any exposure standards are set out in the manufacturer’s MSDS. For further information ing hazardous substances refer to the WorkCover NSW publication Code of Practice For Control of workplace hazardous substances.

5. Inspection and maintenance of plant and equipment

A risk assessment should be conducted before operating plant to identify any hazards that may arise and the control measures to be implemented. The risk assessment should consider at least the following: (a) that appropriate guards, including roll-over protective devices (ROPS) are fitted (b) that the safe working load is displayed (c) record of testing, maintenance, servicing and repair (d) the general mechanical/electrical condition of plant, especially any wear or damage that may effect safe operation (e) compliance with relevant legislation and Australian standards (f) specific controls to prevent entanglement or workers being trapped between moving parts. It is a legal requirement that all plant such as excavators, tractors, etc used for lifting must have their safe working loads displayed and maintained. If the function or condition of plant represents an immediate risk to health and safety, operation should cease and the plant should be withdrawn from use until a risk assessment and appropriate control measures are implemented. 5.1 Routine Inspection Regular planned inspection and adequate maintenance should be carried out to ensure safe operation of all plant used on excavation work, whether leased, hired or owned. Both mechanical and electrical testing should be done. For further information refer to the WorkCover NSW publication Code of Practice: Electrical practices for construction work. The following checks should also be carried out: (a) Daily checks: general condition and maintenance of the plant should be checked daily by the person doing the excavation work. (b) Regular checks: the plant should be inspected by a competent person on a regular basis, or at least every month. 5.2 Repairs and maintenance The contractor using the plant should implement the manufacturer’s recommendations. Repairs should be carried out by a competent person and in accordance with the designer’s or manufacturer’s requirements.

41

42


22/3/00 9:43 AM

Page 46

5.3 Reporting defects Any defects to equipment should be reported immediately to the person responsible for maintaining such plant. Where a defect is likely to pose an immediate risk to health and safety the equipment or plant should not be used until the defect is rectified. Operators are a good source of information about defects in plant because of their day to day experience and they should be encouraged to be involved in reporting such defects. 5.4 Log books and inspection check sheets Owners of plant and associated equipment should keep logbooks and inspection check sheets containing a full service and repairs history of their equipment. These records should be maintained so as to include any hazards relating to the plant in its normal use and kept current and retained for the life of the plant. These should be available upon request by employees or health and safety committee representatives. If the plant is sold, the records should form part of the material forwarded upon sale. 5.5 Roll Over Protective Devices (ROPS) It is a legal requirement that earth moving machinery (designed to have a mass of 700-100,000 kg) must be fitted with a protective structure conforming to AS2294:1997 - Earth-moving machinery - Protective structures. Refer to this Australian Standard for information regarding exceptions to this requirement. Machines fitted with ROPS must have suitable operator restraining devices or seat belts fitted which comply with AS2664:1983 - Earthmoving Machinery - Seat Belts and Seat Belt Anchorages. For further information on the legal obligations on manufacturers and suppliers, see Chapter 8 Legal requirements.

43

6. Training and instruction

Under Section 15.2(c) of the OHS Act 1983 employers must provide training, instruction, information and supervision, as may be necessary, to ensure the health and safety at work of their employees. This should be provided by a competent person. (See definition.) All persons involved in any excavation or associated work should: •

•

be trained to follow systems of work and work practices that enable them to perform their work in a manner that is safe and without risks to health, and; hold appropriate certificates of competencies where required, particularly in the operation and use of load shifting equipment. (For further information see the WorkCover NSW publication A guide for front end loader and excavator drivers.)

Only those persons who have received training and instruction may carry out the work. The training provided and the instruction given should at least include: (a) induction training which complies with the Construction Safety Regulations (as amended) and recommendations outlined in the Code of Practice: Occupational Health and Safety Induction Training for Construction Work 1998. (b) the work method to be used for the excavation or associated work and the manual handling procedures for the work to be carried out, including control measures based on the risk assessment to prevent injury. (c) the correct use, care and storage in accordance with the manufacturer’s recommendations or Australian Standards where appropriate, of: • personal protective equipment; and • tools and equipment to be used. (d) the use of plant and associated equipment, including electrical safety and hazardous substances. (e) procedures to be adopted in the event of accident, injury or other emergency, including evacuation.

44


7. Personal protective equipment (PPE)

22/3/00 9:43 AM

Page 48

The use of PPE to control hazards and risks is the least effective measure and is lowest on the hierarchy of control measures listed in Chapter 2. Control measures should be selected from the highest level possible and be adopted where practicable. The measures at the lower levels are less effective and they require more frequent reviews of the hazards and systems of work. They should only be used when other control measures are impracticable or when, after implementing other controls, a residual risk remains. 7.1 Provision of PPE Before commencing any work, the principal contractor and or contractors should identify any conditions likely to affect the health and safety of persons. If other means of control are not practical, the provision and use of appropriate PPE that complies with the relevant Australian Standard or WorkCover NSW approval must be arranged. Employees should be trained till they are competent in the proper selection, use and maintenance of the PPE. There should be sufficient supervision and monitoring conducted to ensure compliance. 7.1.1 Safety helmets The use of safety helmets may prevent or lessen a head injury from falling objects or a person hitting their head against something. Where there is a likelihood of persons being injured by falling objects and overhead protection is not provided, it is a legal requirement that persons that persons must be provided with and must use an appropriate safety helmet. Appropriate safety helmets should also be provided and used where a person may strike their hand against a fixed or protruding object or where there is a risk of accidental head with electrical hazards. All persons on excavation sites should wear head protection that conforms to AS/NZS 1801:1997 - Occupational protective helmets and be used in accordance with AS/NZS 1800:1998 Occupational protective helmets - Selection, care and use. Note: In some conditions, safety helmets may also have to incorporate protection (such as detachable wide brims) against ultraviolet radiation and sunlight. 7.1.2 Eye protection Dust, flying objects and sunlight are the most common sources of eye damage in excavation work. Where persons are carrying out cutting, grinding, chipping or welding of concrete or metals it is a legal requirement that persons are provided with eye protection complying with AS/NZS 1337:1992 - Eye protectors for industrial applications to reduce the risk of eye injury. Eye protection complying with 45

AS/NZS 1337 should also be provided where persons carry out other work, such as carpentry, where there is a risk of eye injury. Selection, use and management systems should comply with AS/NZS 1336:1997 - Recommended practices for occupational eye protection. There should be sufficient supervision and monitoring conducted to ensure that employees are provided with and use the appropriate eye protection. 7.1.3 Personal hearing protection The contractor doing the work must ensure compliance with the OHS (Noise) Regulation 1996. A noise assessment should be conducted to determine the level of noise that employees are exposed to. Where the noise is in excess of the noise exposure limits, engineering controls should be implemented. (See Section 3.16.) Where personal hearing protection is provided it should conform with AS 1270:1988 - Acoustics - Hearing protectors. Control measures including training should comply with AS/NZS 1269.3:1998 - Occupational noise management Hearing protector program. 7.1.4 Protection from the sun Workers should be protected from the sunlight/UV radiation by shade screens, etc. Where these are not practicable they should wear wide brim hats, long sleeves and long tros and use a sunscreen with an SPF (sun protection factor) rating of at least 15+ on the exposed parts of the body, particularly if short sleeved shirts and shorts are worn. AS/NZS 2604:1998 Sunscreen products: Evaluation and classification provides guidance on selection of sunscreens. Persons should be protected from the risks of eye damage from exposure to the sun by the use of appropriate protective glasses. Such glasses should comply with AS1067.2:1990 Sunglasses and fashion spectacles - Performance requirements. If there are any potential hazards in addition to sunlight, the eye protectors should be selected, used and maintained in accordance with AS/NZS1336:1997 - Recommended practices for occupational eye protection and comply with AS/NZS 1337:1992 - Eye protectors for industrial applications and to AS/NZS 1338.2:1992 - Filters for eye protectors - Filters for protection against ultraviolet radiation. Even with protection, there should be sufficient supervision and monitoring conducted to ensure that workers do not have overlong exposure to strong sunlight and reflection. 7.1.5 High visibility garments/safety reflective vests Persons working near traffic, mobile plant or equipment under operator control, should be provided with and use high visibility 46


22/3/00 9:43 AM

Page 50

garments. Such garments should be selected, used and maintained in accordance with AS/NZS 4602:1999 - High visibility safety garments. Other clothing not covered by the high visibility garment should be light coloured and all garments should be selected for best contrast with the surrounding background. 7.1.6 Waterproof clothing Where waterproof clothing is provided as a system of work relating to weather conditions, site conditions, day or night work, it should be effective and suitable for the task. Waterproof clothing selected should also incorporate light reflective features in accordance with the requirements of Section 7.1.5 above.

8. Legal requirements

8.1 Occupational health and safety Every person at the place of work has a duty under the Occupational Health and Safety Act 1983 (OHS Act), whether as an employer, an employee, a self-employed person or a person in control of the workplace. While the obligation for each person is different, all persons must ensure that the way they carry out their work does not interfere with the health and safety of the other persons who are present at the workplace. Employers’ responsibilities Employers have an obligation to ensure the health, safety and welfare of employees and other persons at the place of work and to comply with the Occupational Health and Safety Act and Regulations.

7.1.7 Clothing for protection against chemicals Where there is a risk that workers may be exposed to chemicals or contaminated environments, they should wear clothing for protection against chemicals that complies with AS 3795:1990 - Clothing for protection against hazardous chemicals.

Employees’ responsibilities Employees have an obligation to take reasonable care for the health and safety of the other persons in the place of work and to cooperate with their employer in the interests of health, safety and welfare. Employees must use appropriate protective equipment for the work being performed.

7.1.8 Respiratory protective equipment If other means of control are impractical and persons could be exposed to harmful atmospheric contaminants such as siliceous dust, welding fumes, etc, then respiratory protective equipment which complies with AS/NZS 1716:1994 Respiratory protective devices must be used (providing it is within the performance capability of the PPE). Such equipment should be selected and utilised in accordance with AS/NZS 1715:1994 - Selection, use and maintenance of respiratory protective devices.

Self-employed persons’ responsibilities Self-employed persons have an obligation to ensure that persons not in their employment are not exposed to risks to their health and safety arising from their conduct while they are at a place of work.

7.1.9 Safety gloves Where there is a risk of hand injury due to exposure to a harmful substance or to a mechanical device, hand protection that complies with AS/NZS 2161:1998 - Occupational protective gloves should be provided and used. 7.2 Maintenance and use of PPE Contractors must provide such information, instruction, training and supervision as may be necessary to ensure that PPE are used and maintained as intended. All PPE used by persons during excavation work should be regularly inspected and replaced as necessary.

47

Responsibilities of the person in control Any person who has, to any extent, control of a workplace, the means of access to or from, or plant or substances used, has an obligation to ensure health and safety regarding the workplace, the means of access to or from and the plant or substances used at the place of work. Manufacturers’/Suppliers’ responsibilities A person who manufactures or supplies any plant for use at work or any substance for use at work shall ensure that the plant or substance is safe and without risks to health when properly used and provide, or arrange for the provision of, adequate information about the plant or substance to the persons to whom it is supplied to ensure its safe use.

48


22/3/00 9:43 AM

Page 52

8.2 Workers Compensation insurance Anyone who employs workers, and/or who in some cases, engages contractors must maintain a workers compensation insurance policy. Penalties apply for failing to have a policy in place.

An employer may not dismiss an employee because he or she makes a complaint about a matter they consider to be a health and safety risk or because he or she is a member of an OHS committee or exercises any of his or her functions as such a member (Section 26 of the OHS Act).

All employers have a legal liability to pay workers compensation to workers who are injured in the course of their work, and employers are required by law to hold a workers compensation insurance policy from a licensed WorkCover NSW insurer to cover that liability.

8.4 Statutory provisions The following Acts and Regulations apply to excavation work: • Construction Safety Act 1912 and Regulations • AS1337:1984 - Eye Protectors for Industrial Applications • AS1716:1984 - Respiratory Protective Devices • AS1891:1983 - Industrial Safety Belts and Harnesses • AS1576:1995 - Scaffolding • Construction Safety Amendment (Amenities and Training) Regulation 1998 • Occupational Health and Safety Act 1983 and Regulations • OHS (Manual Handling) Regulation 1991 • National Standard for Manual Handling • OHS (Confined Spaces) Regulation 1990 • AS 2865:1986 Safe Working in a Confined Space • OHS (Noise) Regulation 1996 • AS1259.1:1990 - Sound Level Meters - Part 1: Nonintegrating • AS1269:1989 - Acoustics - Hearing Conservation • OHS (Hazardous Substances) Regulation 1996 • OHS (First Aid) Regulation 1989 • OHS (Floors, ageways and Stairs) Regulation 1990 • AS1657:1985 - SAA Code for Fixed Platforms, Walkways, Stairways and Ladders • OHS (Committees in Workplaces) Regulation 1984 • Workplace Injury Management and Workers Compensation Act 1998

For workers compensation insurance purposes, the Workplace Injury Management and Workers Compensation Act 1998 defines a ‘worker’ to be any person who works under a contract of service or apprenticeship with an employer, whether by way of manual labour, clerical work or otherwise, and whether the contract is expressed or implied, or is oral or in writing. In addition, the Act deems certain other persons to be workers for workers compensation purposes eg some types of contractors. For assistance to clarify your obligation your insurer or WorkCover NSW Information Centre on 13 10 50. WorkCover NSW also has available a guideline on insurance for contractors called Interim Guidelines for Workers Compensation for Contractors and sub-contractors. 8.3 Occupational health and safety (OHS) committees Workplace OHS committees can be very useful to both employees and employers to encourage better communication and relations between persons carrying out the work and management when identifying and resolving occupational health and safety matters. OHS committees may also assist during the consultation process when employers are determining what safeguards will be provided for persons carrying out the work. The OHS Act requires that a committee must be established at a place of work if there are 20 or more employees and the majority of employees request it or if WorkCover directs the establishment of such a committee. A committee member has the power under section 25 of the OHS Act to: (a) review the measures taken to ensure health and safety at the workplace. This may include assisting in the development of safe systems of work and recommending appropriate training and education. (b) investigate health and safety matters at the place of work and make recommendations to the employer. (c) carry out inspections and obtain relevant information. (d) request a WorkCover inspection.

The following legislative requirements are mentioned in the code: • Section 2.4(f) OHS (Manual Handling) Regulation 1991 • Section 3.3 Construction Safety Regulations • Section 3.5 Construction Safety Regulations • Section 3.6.1 Construction Safety Regulations • Section 3.8 Construction Safety Regulation • Section 3.9 Construction Safety Regulations • Section 3.10 Construction Safety Regulations • Section 3.11 Construction Safety Regulations • Section 3.12.2 Construction Safety Regulations • Section 3.13 OHS (Manual Handling ) Regulation 1991 • Section 3.14.1 Construction Safety Regulations • Section 3.14.3 Construction Safety Regulations • Section 3.14.4 Construction Safety Regulations

Committee must be provided with training that assists them to exercise their functions. 49

50


22/3/00 9:43 AM

•

Section 3.14.5

• •

Section 3.16 Section 4.1

•

Section 4.3

•

Section 4.4

• • • • • • •

Section Section Section Section Section Section Section

•

Section 8.2

•

Section 8.3

5 5.5 6 7.1.1 7.1.2 7.1.3 8.1

Page 54

OHS (Floors, ageways and Stairs) Regulation 1990 OHS (Noise) Regulation 1996 OHS (Hazardous Substances) Regulation 1996 OHS (Confined Spaces) Regulation 1990 OHS (Hazardous Substances) Regulation 1990 Construction Safety Regulations Construction Safety Regulations Construction Safety Regulations Construction Safety Regulations Construction Safety Regulations OHS (Noise) Regulation 1996 Legal requirements under the OHS Act 1983 Workplace Injury Management and Workers Compensation Act 1998 OHS (Committees in Workplaces) Regulation 1984

The provisions of the Construction Safety Act, the OHS Act, their associated regulations, Australian Standards and Worksafe guides and codes of practice mentioned above are mandatory provisions in legislation and must be complied with. They have been mentioned in this code of practice to provide assistance in directing readers to other legislative requirements which may have some application. The list is not exhaustive and is included in this code by way of assistance only. A further listing of the current Australian Standards mentioned in this code is provided in the Further Information section.

Definitions

The following definitions are for the purposes of this code: Access shaft A vertical or inclined opening excavated below the ground level primarily used for the access of persons and/or material. Angle of repose The angle to the horizontal at which the material in the cut face is stable and does not fall away. Barrier Anything that blocks a way or makes a separation ie shade cloth, sheet ply, plastic mesh webbing, etc. Note: Barriers are not necessarily designed to prevent falls. Single strand plastic tapes should not be used as a barrier. Barricade An object such as jersey kerb truck or plant capable of providing effective protection against traffic entering the work site. Batter or Slope An angle in relation to the horizontal surface. Benching The horizontal stepping of the face, sides, walls or bottom of an excavation. Competent person means a person who has acquired through training, qualification, or experience, or a combination of these, the knowledge and skills enabling that person to perform the specified tasks. Confined Space See Section 4.3. Construction work includes: a. building, including excavation, and the construction, alteration, renovation, repair, maintenance and demolition of all types of buildings or structures. b. civil engineering, including excavation, and the construction, structural alteration, repair, maintenance and demolition of, for example, airports, docks, harbours, inland waterways, dams, river and avalanche and sea defence works, roads and highways, railways, bridges, tunnels, viaducts and works related to the provisions of services such as communications, drainage, sewerage, water and energy supplies.

51

52


22/3/00 9:43 AM

Page 56

c. the erection and dismantling of prefabricated buildings and structures as well as manufacturing of prefabricated elements on the construction site. Contractor The person responsible for the excavation work. Depending on the contractual arrangements in place, the contractor doing the work may be an employer, self-employed person or a person in control within the of the OHS Act. Cover A steel plate or other suitable material capable of withstanding the loads that may be imposed upon it and of sufficient weight or secured to prevent removal by children.

Health and Safety Management Plan A plan that gives due consideration to OHS issues with the objective of eliminating and if not practicable minimising risks of injuries or ill health at a place of work. MSDS (Material Safety Data Sheet) A document that must be prepared by a manufacturer before supplying a hazardous substance to another person for use at work. The MSDS must identify the hazardous substance to which it relates and must set out certain information about the substance including recommended uses, chemical and physical properties, any relevant health-hazard information, any information concerning precautions to be followed in relation to its safe use and handling.

Cutting An open cut excavation having a single wall or face.

Open excavation An excavation where the width is equal to or greater than the depth.

Employee An individual who works under a contract of employment or apprenticeship.

Pier hole A hole for a purpose such as pouring footings for a building or structure.

Employer A corporation which, or an individual who, employs persons under contracts of employment or apprenticeship.

Principal contractor The person with overall responsibility for the construction work and includes owner builder. Depending on the contractual arrangements which are in place, the principal contractor may be an employer, self-employed person or a person in control within the of the OHS Act.

Excavation work Work involved in the excavation or filling of trenches, ditches, shafts, drifts, rises, tunnels, pier holes, cuttings, benches, wells or canals or any similar work. Face An exposed sloping or vertical surface resulting from the excavation of material. Fence Continuous enclosure not less than 1800mm in height that prevents unauthorised access to the work place and of such strength to remain erect in position during all conditions. Geotechnical engineer An engineer whose qualifications are acceptable for hip of the Institution of Engineers, Australia and who has qualifications and experience in soil stability and mechanics and excavation work. Guard Rail A structure of timber, steel, concrete or a combination capable of providing effective protection against traffic entering the work site. Handrail A rail one meter in height (plus or minus 100mm) effectively ed, secured and of such rigidity and strength capable of providing so as to prevent persons falling. 53

Plant Includes any machinery, equipment (including scaffolding), appliance, implement or tool and any components or fittings or accessories to them. Runners Any timbers, metal or sheet piling used to form the vertical of an excavation . Self-Employed Person An individual who works for gain or reward otherwise than under a contract of employment or apprenticeship, whether or not they employ others. Shoring The use of timber, steel or other structural material for the purpose of providing effective and adequate temporary to maintain the stability of the walls of an excavation. Strut or screw jack or flying shore A timber or steel member usually horizontal in compression, resisting thrust or pressure from the face or faces of an excavation. Screw jack struts are adjustable. structure A shoring system to maintain the stability of the walls and roof of an excavation and includes a trench shield. 54


22/3/00 9:43 AM

Page 58

Trench An excavation having a depth that exceeds its width, measured at the bottom. Trench shield A structure with two vertical side plates permanently braced apart by cross frames or struts designed to resist the pressure from the walls of a trench and capable of being moved as a unit. The trench shield is intended to provide a safe working place for persons while work in an excavation is being carried out. Waling A horizontal beam ing vertical timbers, runners or sheeting. Work method statement A statement that outlines the manner of carrying out the work in a safe and healthy way. Zone of influence The volume of soil around the excavation affected by any external load, eg vehicles, plant, excavated material. Note: This volume is generally assumed to be that formed by planes extending from the load to a maximum angle to the horizontal of 30 degrees in the case of sand and 45 degrees for clay.

Appendix 1

Checklist Hazard Identification, Risk Assessment and Control Measures This Appendix contains sample checklists to assist in identifying common hazards associated with excavation work, assessing the risks and controlling them. The checklist is not meant to be comprehensive as circumstances will vary from site to site. A hazard identification risk assessment and control process should be carried out by the excavation contractor in consultation with the principal contractor to determine if persons are at risk. When selecting control measures, contractors should always aim first at eliminating the hazard and if not practicable minimise the risks. The use of personal protective equipment PPE or the adoption of istrative controls should be regarded as a last or supplementary measure. (See Section 3.4.)

Hazard 1: Lack of planning and preparation Has the work been planned and prepared to ensure that all work is carried out safely, including factors raised in Chapter 2 of this Code? Yes: Go to the next hazard No: Go to Factors to be considered

Factors to be considered

Yes

Has there been consultation with all appropriate persons / authorities involved in the work? Has the principal contractor planned for all health and safety factors under his control? See Chapter 2? Has the contractor(s) planned for all health and safety factors under his control? See Chapter 2? Has the hazard identification, risk assessment and control process been carried out taking into site specific factors? In preparation for commencement of work, has a health and safety management plan been developed and documented? In preparation for commencement of work, have controls identified by the risk assessment been implemented? Have site specific emergency procedures been developed? (See Section 2.8)

55

56

No


22/3/00 9:43 AM

Page 60

Hazard 3:

Hazard 2: Collapse or failure of all or part of an open excavation or trench Is there a risk of persons being injured as a result of the collapse or failure of any part of the excavation? Yes: Go to Risk Assessment No: Go to next hazard

Risk Assessment

No

Lack of inspection of systems

Is the excavation work examined regularly to ensure that the excavation and its ing systems are stable and intact to ensure that work proceeds safely, including factors raised in Section 3.5? Yes: Go to next hazard No: Go to Risk Assessment

Yes

Does the depth of the excavation present a risk of injury if a collapse or failure occurs? Does the nature of the work require workers in the excavation to squat or bend down, thereby increasing the risks of injury in case of collapse? eg. bending to place a rubber ring in a pipe t. Does the nature of the soil or strata present a risk of collapse (soil type, shale, floaters)? Are there signs of fractures or faults in the rocks? Is moisture or water present which will affect the stability of the excavation? Will rain, snow, water seepage, run-off or other sources of water increase the risk of collapse? Will there be any static loads within the zone of influence of the excavation? Eg spoil piles, buildings, structures. Will there by any dynamic loads within the zone of influence of the excavation? Eg traffic, excavation equipment. Are there sources of vibration (eg. machinery, traffic, blasting.) that may increase the risk of collapse? Will it be long before the excavation is ed or backfilled? Was the ground previously disturbed thus increasing the risk of collapse? Are there adjacent excavations that may increase the risk of collapse in either the planned excavation of the existing adjacent one? Do ading buildings and structures impose additional loads on the excavation thus increasing risk of collapse? Are there any adjacent roads, footpaths, or other access ways that may be undermined by the excavation? Is there a risk that shoring been designed without taking all factors listed in Section 3.2 into ? For battered or benched walls, does the angle of repose exceed the angle recommended by a geotechnical engineer or 45°? Are there any other site-specific factors that may lead to collapse of the excavation?

Risk Assessment

No

Have you ticked any of the unshaded boxes above? ❑ Yes: Go to Control Measures. Review Section 3.5 of this Code ❑ No: Go to next hazard

Control Measures

Tick where appropriate

Do not allow persons in excavation at all. Ensure no one enters the excavation until any identified risks and hazards have been assessed and appropriate controls are in place. Develop and implement a program of regular inspection of excavation systems. Follow guidelines of relevant standards and codes. Specify here any other site specific controls:

Have you answered ‘Yes’ to any question: ❑ Yes: Go to Control Measures. Review Sections 3.2, 3.3 and 3.4 of Code ❑ No: Go to next hazard

Control Measures


Do not allow persons in excavation at all. Ensure no one enters the excavation until shoring is in place. Obtain advice from appropriately qualified engineers Follow guidelines of relevant standards and codes. Install shoring designed in accordance with Section 3.2. Bench or batter excavation in accordance with Section 3.3.1 Engage competent person to supervise progress of excavation work. Remove/reduce loads near edge of excavation in accordance with Section 3.10. Provide stops or barriers to prevent approach of machinery near edge of excavation. Reposition machinery causing vibration to a safe distance from edge. Minimise length of unretained trench. Ensure installation and removal of shoring is carried out from outside the excavation. Obtain written certification from a geotechnical engineer for the safe angle of repose under existing and potential site conditions. Specify here other site specific controls:

57

Yes

Is excavation work examined prior to commencement of work? Is excavation work examined at regular intervals? Are inspections conducted by a competent person? Are inspections documented? Has there been any activity that may affect the stability of the excavation? eg collapse of any part of excavation, fall of materials into the excavation, adverse weather conditions, use of explosives. Have all of the conditions listed in Section 3.5 of this Code been considered or monitored as part of the regular inspection of systems? Are there any other site-specific factors regarding inspection of excavation systems?

58


22/3/00 9:43 AM

Page 62

Hazard 4: Drowning Is there a risk that the excavation may collect or retain water (or slurry or other liquids) such that there a risk of a person drowning as a result of fall into the water? No: Go to next hazard Yes: Go to Risk Assessment

Risk Assessment

No

Appendix 2

Example of a Hierarchy of Risk Control Measures Preventing a person from being injured by excavation wall collapse

Yes Level 1

Is there a risk of a person drowning as a result of a fall into the water? Is there a risk that the excavation may collect or retain water/slurry/other liquid that will constitute a hazard to children, or persons in the vicinity Will rain, snow, etc increase the likelihood of the excavation retaining water and thus increase the risk of drowning? Does the emergency plan include rescue procedures for persons falling into water/slurry/other liquid? Are there other site specific factors that may increase the risk of drowning?

Do it differently: Choose a different method of construction

by, for example, doing all the work without requiring a person to enter the excavation. Note: this eliminates the risk of being injured by trench collapse. Level 2 Modify what you already do: By installing shoring or

Have you answered ‘Yes’ to any question: ❑ Yes: Go to Control Measures. Review Section 3.6.3 of this Code ❑ No: Go to next hazard

Control Measures


Provide positive means of fall protection such as fencing, handrails and safety harnesses. Provide flotation vests. Provide rescue means such as lifebouys or rescue boats Develop and implement emergency rescue procedures. Ensure availability of qualified personnel to ister expired air resuscitation and the prominent display to a R chart. Specify here other site specific controls.

battering or benching the walls of an open topped excavation and using an appropriate means of access, the risks of excavation collapse are minimised. Level 3 Other controls: Barriers be put in place to keep persons away from the most dangerous areas as much as possible. Doing excavation work this way requires additional training, onsite management and more frequent excavation checking to ensure the safety of persons.

Hazard 5: Exposure to excessive or prolonged noise Has the work been planned and prepared to ensure that persons are not exposed to noise levels which may become a risk to hearing or health? Yes: Go to next hazard No: Go to Risk Assessment

Risk Assessment

No

Yes

Will the noise from machinery or equipment on site create unsafe noise levels? Will workers be exposed to lengthy periods of noise? Are there other site specific factors that would increase this risk? Have you answered ‘Yes’ to any question above: ❑ Yes: Go to Control Measures. Review Section 3.16 of this Code ❑ No: Go to next hazard

Control Measures


Ensure compliance to Code of practice for noise management & protection of hearing at work. Conduct a noise assessment by an appropriately qualified person. Introduce engineering controls to eliminate or reduce noise. Minimise exposure to noise. Provide hearing protectors which comply with AS 1270. Specify here other site specific controls.

59

60


22/3/00 9:43 AM

Page 64

Appendix 3 A typical example of a safe work method statement (See also the WorkCover NSW document: Guidelines for writing work method statements in plain English)

PROJECT: CONTRACTOR:

SAFE WORK METHOD STATEMENTS (A GUIDELINE) Contractors are often required to submit Safe Work Method Statements. Many contractors submit “Technical Procedures” for carrying our construction work processes as Safe Work Method Statements (SWMS). These documents are often not a SWMS as required for Hazard Identification & Risk Assessment. SWMS should be submitted to the main contractor prior to commencing on-site work. A Safe Work Method Statement requires the work method to be presented in a logical sequence. The hazards associated with each process are to be identified, and the measures for controlling these hazards specified. Any job, no matter how complex, can be broken down into a series of basic job steps that will permit a systematic analysis of each part of the job for hazards and potential accidents. The description of the process should not be too broad that it leaves out activities with the potential to cause accidents and prevents proper identification of the hazards; nor is it necessary to provide too fine a detail of the tasks. A “hazard” may be either intrinsic or inherent, existing or potential, an unsafe condition and/or an unsafe act - ie: a dangerous location, an unsafe (hazardous) work process, or a potentially hazardous task as a stage of the construction work process. The “hierarchy of control measures” is the recommended procedure for Hazard Control, with personal protective equipment (PPE) the least preferred. In some situations a combination of control measures may need to be used. Reference to Legislation, Code of Practice or Australian Standards is not an acceptable alternative for Hazard Control or Risk Management; the actual procedure or control must be documented. Special Work Processes involving inherent hazards requiring special safety equipment must be referred to as the Safe Work Practice to be incorporated in the Standard Work Procedure eg: “When grinding or disc cutting, safety spectacles or goggles and a full face shield shall be worn”. The SWMS should nominate the occupations and the number of employees required to safely do the task(s) involved. Safety and/or skills training provided or required to be completed prior to commencing work is to be identified, together with any special qualifications, permits, licenses, certificates of competency required by the employees and/or statutory regulations. Copies of such documents and training records should be provided with the SWMS. The SWMS is also required to specify the type/capacity and description of the mechanical aids, plant and mobile equipment that is to be used in the construction work process. of the workforce should be involved/consulted in the development of any SWMS. The Site Safety Induction should ensure that all persons involved in carrying out the work understand the SWMS.

61

62

63

make it safe: get it ready: do this first: do this next: make it secure: clean up/put away:

(Unsafe conditions and unsafe acts)

(Safety measures/Safe Work Practices/PPE)

64

5. 6.

5. 6.

Examine each to find possibilities that could lead to an accident.

Each step should accomplish some major task and be in a logical sequence

HAZPAK

ensure the proposed controls will be maintained.

potential severity factors. Include the measure to be taken to

minimise the hazards, the risk of injury/damage, and/or

Specify what action/procedures will be taken to eliminate or

Name:…………………………………… Position:……………………………… Signature:………………… Date:……………

STEP

STEP 1

Identify the hazards associated with each step.

Break the job down into steps.

See

4.

4.

PROPOSED ACTION/ CONTROL MEASURE

3.

3.

WORK SEQUENCE BASIC JOB STEPS

2.

1. 2.

RISK SCORE

Office use only

………………………

File No.

PERSONAL PROTECTIVE EQUIPMENT: 1.

POTENTIAL HAZARDS

WORK METHOD STATEMENT

SAFE WORK PRACTICES:

Job/Task or Process:

of……………………………

Cover Page Two


Name:…………………………………… Position:……………………………… Signature:………………… Date:……………

1. 2. 3. 4. 5. 6.

22/3/00 9:44 AM

(Basic steps in logical sequence - what is to be done, not how)

JOBS/TASKS/PROCESSES

Completed and/or required

Training

Licenses/Qualifications/Permits

Qualifications

(Req’d to do the work safely)

No. of employees

Office use only

………………………

File No.

EQUIPMENT DETAILS Static Plant and Equipment Mobile Plant and Equipment Safety/Emergency Equipment Personal Protective Equipment (PPE) HAZARDS CONTROL MEASURES

WORK METHOD STATEMENT

PERSONNEL DETAILS Trades/Skills/Work Teams

Occupations

Job/Task or Process:

of……………………………

Cover Page One


295186 Workcover (before impos) Page 66

Further Information ensure the proposed controls will be maintained.

minimise the hazards, the risk of injury/damage, and/or

potential severity factors. Include the measure to be taken to

Excavators are asked to give at least two working days notice of intention to excavate to enable plans and location details to be forwarded. Enquiries may be faxed to 1300 652 077 at any time for processing during office hours. Useful publications NSW Workcover Codes of practice • Code of practice: Electrical practices for construction work. • Code of practice: Noise management and protection of hearing at work. • Code of practice: Amenities for construction work. • Code of practice: Tunnels under construction. • Code of practice: Overhead protective structures. • Code of practice: OHS induction training for construction work. • Code of practice for control of workplace hazardous substances.

65

STEP

STEP

to an accident. a logical sequence

STEP

Examine each to find possibilities that could lead

Location of Services The NSW Dial Before you Dig service is available to assist in the location of all service utilities and as a part of the National Dial Before you Dig service. By ringing 1100, an excavator is automatically connected to the appropriate state service and can obtain information on the location of utilities and local government services. The service operates from 7am to 6pm Monday to Friday and advises which utilities have underground facilities in your area of excavation and then facilitates communication between all parties.

STEP

Specify what action/procedures will be taken to eliminate or

Page 68

HAZPAK

Identify the hazards associated with each step.

Each step should accomplish some major task and be in

See

22/3/00 9:44 AM

Break the job down into steps.

PROPOSED ACTION/ CONTROL MEASURE RISK SCORE WORK SEQUENCE BASIC JOB STEPS

POTENTIAL HAZARDS

WORK METHOD STATEMENT of Page


File No.

Office use only

………………………


Guides • A guide for front end loader and excavator drivers • Guide for working near traffic and mobile plant • Use of personal protective equipment at work - a guidance note • Skin cancer and outdoor workers - a guide for workers • Skin cancer and outdoor workers - a guide for employers • How to prevent silicosis. • A guide to dust hazards. • HazPak • Worksafe Exposure Standards for Atmospheric Contaminants in the Occupational Environment • Worksafe guidance Note for the Assessment of Health Risks Arising from the Use of Hazardous Substances in the Workplace.

66


22/3/00 9:44 AM

Page 70

Standards and Codes offer practical guidance on health and safety when carrying out excavation work. The appropriate Acts and Regulations are listed above. However, these are subject to change from time to time. For further information the WorkCover Information Centre on: 131 051. For information about the comprehensive range of other codes of practice, certification guides and OHS, rehabilitation and workers compensation publications the WorkCover Publications Order Line: (02) 9370 5303. Australian Standards Standards are available directly from Standards Australia. AS/NZS 1576.1:1995 AS 1657:1992

AS/NZS 1800:1998 AS/NZS 1801:1997 AS/NZS 1336:1997 AS/NZS 1337:1992 AS/NZS 1338.1:1992

AS/NZS 1338.2:1992 AS/NZS 1338.3:1992 AS 1269.3:1998 AS1270:1988 AS/NZS 1715:1994 AS/NZS 1716:1994 AS 1891:1983 AS/NZS 2161.2:1998 AS/NZS 2161.3:1998 AS/NZS 2161.5:1998 AS 2225:1994 AS 2294:1997

67

Scaffolding - General requirements Fixed platforms, walkways, stairways and ladders - Design, construction and installation Occupational protective helmets Selection, care and use Occupational protective helmets Recommended practices for occupational eye protection Eye protectors for industrial applications Filters for eye protectors - Filters for protection against radiation generated in welding and allied operations Filters for eye protectors - Filters for protection against ultraviolet radiation Filters for eye protectors - Filters for protection against infra-red radiation Occupational noise management Hearing protector program Acoustics - Hearing protectors Selection, use and maintenance of respiratory protective devices Respiratory protective devices Industrial safety belts and harness Occupational protective gloves General requirements Occupational protective gloves Protection against mechanical risks Occupational protective gloves Protection against cold Insulating gloves for electrical purposes Earthmoving Machinery - Protective Structures

AS 2264:1983 AS/NZS 2604:1998 AS 2865:1986 AS 3795:1990

Earthmoving Machinery - Seat Belts and Seat Belt Anchorages Sunscreen products - Evaluation and classification Safe working in a confined space Clothing for protection against chemicals

Traffic Control Standards: AS 1742 (Set) Manual of uniform traffic control devices AS 1742.1-1991 Manual of uniform traffic control devices - General introduction and index of signs AS 1742.2 -1994 Manual of uniform traffic control devices - Traffic control devices for general use AS 1742.3-1996 Manual of uniform traffic control devices - Traffic control devices for works on roads AS 1742.4-1986 Manual of uniform traffic control devices - Speed controls AS 1742.5-1997 Manual of uniform traffic control devices - Street name and community facility name signs AS 1742.6-1990 Manual of uniform traffic control devices - Service and tourist signs for motorists AS 1742.7-1993 Manual of uniform traffic control devices - Railway crossings AS 1742.8-1990 Manual of uniform traffic control devices - Freeways AS 1742.9-1986 Manual of uniform traffic control devices - Bicycle facilities AS 1742.10-1990 Manual of uniform traffic control devices - Pedestrian control and protection AS 1742.11-1989 Manual of uniform traffic control devices - Parking controls AS 1742.12-1986 Manual of uniform traffic control devices - Bus, transit and truck lanes AS 1742.13-1991 Manual of uniform traffic control devices - Local area traffic management AS 1742.14-1996 Manual of uniform traffic control devices - Traffic signals SAA HB81.1-1996 Field guide for traffic control at works on roads - Short-term urban works, daytime only SAA HB81.2-1996 Field guide for traffic control at works on roads - Short-term rural works, daytime only SAA HB81.3-1997 Field guide for traffic control at works on roads - Mobile works SAA HB81.4-1998 Field guide for traffic control at works on roads - Short-term night works SAA HB81.5-1998 Field guide for traffic control at works on roads - Works on unsealed roads SAA HB81.6-1998 Field guide for traffic control at works on roads - Bituminous surfacing works 68

Code Of Practice Excavation 6l4u3g

Overview 26281t

More details 6y5l6z

Related Documents 3h463d

Code Of Practice Excavation 6l4u3g

Code Excavation 3z2d2l

Code Of Practice Lta 6l3l1i

Lifting Code Of Practice rx1x

Scaffolding Code Of Practice 495ux

Bcga Code Of Practice 1j2124