TRENCHING AND EXCAVATION - Logan WHS Wiki

Trenching and Excavation Procedure Version 2.0 27/02/2017 DM#11098857 of 17 Uncontrolled if printed. For the latest approved version, refer to council DM.

TRENCHING AND EXCAVATION

Health and Safety Procedure

HS-PRO-003



CONTENTS 1. POLICY STATEMENT ................................................................................................................. 3 2. PURPOSE & OBJECTIVE ........................................................................................................... 3 3. SCOPE ........................................................................................................................................ 3 4. RESPONSIBILITIES .................................................................................................................... 4 5. DEFINITIONS .............................................................................................................................. 5 6. PLANNING FOR TRENCHING AND EXCAVATION .................................................................... 6

Identify the Work to be Undertaken ....................................................................................... 6 Implement Isolation Controls ................................................................................................. 6 Implement Access Controls .................................................................................................. 6 Review Trenching & Excavation SWMS and Complete a JSEA ............................................ 7

7. DURING TRENCHING AND EXCAVATION ................................................................................ 8 Excavated material and loads near excavations ................................................................... 9 Special Considerations Regarding Excavations Deeper Than 1.5m .................................... 10

7.2.1. Trenching and Excavation Work Permit and Emergency Planning ............................... 10 7.2.2. Confined Space Entry .................................................................................................. 10 7.2.3. Benching and Battering ................................................................................................ 10 7.2.4. Shoring ........................................................................................................................ 11

8. FOLLOWING TRENCHING AND EXCAVATION ....................................................................... 14 9. TRAINING & COMPETENCE .................................................................................................... 14 10. EMERGENCY RESCUE ........................................................................................................ 14 11. MEDICAL ASSESSMENT ...................................................................................................... 14 12. MONITORING AND REVIEW ................................................................................................. 15 13. ASSOCIATED DOCUMENTS ................................................................................................ 15 14. LEGISLATIVE AND OTHER REFERENCES ......................................................................... 15 15. DOCUMENT CONTROL ........................................................................................................ 16 APPENDIX 1- Register Of Trenching and Excavation Equipment ..................................................... 17 APPENDIX 2 - Register of Trenching and Excavation Emergency Rescue Equipment ..................... 17



Subject: Trenching and Excavation

DM #: 11098857 Version #: 2.0 27/02/2017

Review date: 27/02/2022 Status: Approved

Document Owner: Health and Safety Program Leader

Documents affected by changes to this document Document Name DM #

Trenching and Excavation Safe Work Method Statement (HS-SWMS-003) 11099104

Trenching and Excavation Permit (HS-FRM-003) 8543847

1. POLICY STATEMENT Logan City Council (Council) values the health and safety of its employees and all others who may be affected by our operations, buildings and facilities.

2. PURPOSE & OBJECTIVE To minimise the risk of incidents or injury from hazards associated with Trenching and Excavations, and to fulfil relevant legislative requirements. This safety procedure applies to all activities concerning trenching and Excavations under the control of Council. It specifies mandatory requirements for creating, entering and working in trenches and Excavations and should be followed in conjunction with the Construction and High Risk Work Directive (HS-DIR-002).

3. SCOPE The safety procedure is applicable to trenching and Excavation activities conducted by Council employees and contractors. It applies to Council staff, agency workers, contractors, work experience students, trainees, visitors, volunteers, the public and others who may affect or be affected by Council workplaces or Council work activities, or by plant or substances used at the workplace. This procedure does not apply to:

• a trench used as a place of interment (i.e. a grave site) • road Excavation on existing roadways for resurfacing activities



4. RESPONSIBILITIES Title Responsibilities Branch Managers and Program Leaders

• Ensure that personnel are aware of, and comply with, this procedure. • Ensure the ongoing effectiveness of the procedure in controlling the

identified risk exposures in accordance with the “Monitoring and review” section of this procedure (Section 13) Undertake Safe Act Observations as part of the monitoring and review process.

Supervisors and Contractors • Implement this procedure, ensuring that the potential risks associated with trenching and Excavation are assessed and appropriate controls implemented.

• Ensure all workers comply with this procedure. • Investigate incidents arising in the application of this procedure,

implementing any necessary preventative/corrective actions following an incident or in the identification of a risk or hazard.

• Ensure workers receive training as required. • Ensure that appropriate equipment, tools and PPE are available to

execute the work safely. Personnel directly involved in Trenching and Excavation activities

• Comply with the requirements of this procedure and, as applicable, the Trenching and Excavation Safe Work Method Statement (HS-SWMS-003).

• Report any incidents, near misses, risks or hazards. • Participate in and complete all necessary training.



5. DEFINITIONS Term Definition Authorised person (SWNELP; Safe work near exposed live parts)

A person having attained the necessary skills and qualifications to secure appropriate written permission from Energex to work near overhead or underground electric lines.

Barrier A physical structure which blocks or impedes something. Barricade Any object or structure that creates a barrier obstacle to control, block

passage or force the flow of traffic in the desired direction. Backfill Material used for refilling trenches and Excavations. Battering The tapering back of the wall of a trench or Excavation, stabilising the wall

by reducing the wall height. Benching The creation of steps in the wall of a trench or Excavation, stabilising the

wall be reducing the wall height. The benching is cut at a comparable horizontal / vertical ratio.

Competent Person A person who has through a combination of training, education and experience, acquired knowledge and skills enabling that person to perform correctly the specified task.

Excavation Excavation means a trench, tunnel or shaft, but does not Include: • a mine; or • water bore to which the Water Act 2000 applies; or • a trench for use as a place of interment

Exclusion Zone An area from which all unauthorised persons are excluded during Excavation work.

Fitness For Work Sufficiently alert and able to perform usual duties. Not impaired by drugs, alcohol or fatigue.

Geo-Technical Engineer An engineer whose qualifications are acceptable for membership of the Institution of Engineers, Australia and who has qualifications and experience in soil stability and mechanics and Excavation work.

Hoarding Refer; ‘Barricade’ Shall Means mandatory. Shoring The use of timber, steel or other structural material to support an Excavation

in order to prevent collapse so that construction work can proceed. Should Means advisory. SWNELP Safe work near exposed live parts. Refer; ‘Authorised person’

Trench A horizontal or inclined way or opening: • the length of which is greater than its width and greater than or equal to

its depth; and • that commences at and extends below the surface of the ground; and • that is open to the surface along its length.

Trench Shield Engineered shoring (usually made of metal). Hydro Excavation (Vacuum Excavation)

Hydro Excavation is a process high pressure water is used to loosen soil, rocks, clay, gravel and other earth material while it is continually "sucked up" into a debris tank for later disposal.

Zone of Influence The volume of soil around the Excavation affected by any external load (e.g. vehicles, plant, excavated material).



6. PLANNING FOR TRENCHING AND EXCAVATION

Identify the Work to be Undertaken Identify the work to be undertaken, and the depth of the trench or Excavation required. Examples of operations that may relate to this procedure include, but are not limited to installation or repair of water mains, stormwater, valves or manholes. Trenches and Excavations that are 1.5 metres or more are considered high risk due to entrapment hazards and the potential to contain an unsafe atmosphere. Refer to the Working at Height Procedure (HS-PRO-002), Confined Space Entry Procedure (HS-PRO-006) and the Trenching and Excavation SWMS (HS-SWMS-003) for further detail.

Implement Isolation Controls Contact ‘Dial Before You Dig’ (Phone ‘1100’) to obtain relevant information about the service (location, type, depth, restrictions to be followed). If dial before you dig is unavailable, it shall be assumed there are services in the area and mechanical Excavation shall not be undertaken. Utilities companies may need to be consulted. Record the information and ensure that all personnel involved in the trenching or Excavation works are made aware of the location, depth and type of services in the vicinity of the works. Isolation measures (including lock out) must be implemented to ensure that when persons are required to enter an Excavation, all materials, or conditions harmful to persons occupying the Excavation are rendered inoperable. Refer to Lockout and Tagout Procedure (HS-PRO-019). If isolation is not possible then the risk must be minimised so far as is reasonably practicable with emergency planning protocols in place and on standby in accordance with Section 10.

Implement Access Controls During all stages of the trenching and Excavation works, an exclusion zone shall be created with the appropriate barricading in place to prevent unauthorised personnel, mobile plant or workers from inadvertently gaining access to the Excavation. A trench or Excavation greater than 1.5 metres deep shall have barricading around the external perimeter of the work area (preventing public or unauthorised access) in addition to barricading of the internal Excavation itself (preventing worker access). This process is known as double barricading. This should also be considered and risk assessed if there are a number of different work-fronts, cross-trades or multiple Excavations in the same work area to ensure that the risk of workers falling into an Excavation is appropriately controlled. Erect exclusion zones using warning signage and protective barriers. Barriers and signage shall remain in place:

• while work is being carried out in preparation for commencement • during work being carried out in the trench or Excavation • during completion activities of work in a trench or Excavation



Review Trenching & Excavation SWMS and Complete a JSEA Review the Trenching and Excavation SWMS (HS-SWMS-003) and gain an understanding of the identified generic hazards and appropriate control measures for trenches or excavations greater than 1.5m deep. Where the trenching and excavation work involves other high risk construction activities all relevant SWMS must be followed. Refer to the Construction and High Risk Work Directive (HS-DIR-002). Complete a Job Safety and Environmental Analysis (JSEA) for the task specific work to be undertaken associated with the trenching or excavation and determine control measures to be implemented.(refer to Job Safety Analysis Procedure (DM#8571966) for further details of how to complete a JSEA). The JSEA shall record all identified hazards and control measures within the scope of work to be undertaken as part of the trenching or Excavation. Consider the following when completing the JSEA:

• any identified underground or overhead services • control measures for any ‘Hot Work’ to be undertaken • hazardous substances to be used or likely to be encountered (such as fumes or gases) • site access such as; physical terrain, existing and changing ground conditions and types of

soil • the weather and environmental conditions (e.g. wind, rain, poor lighting, etc.) • consideration of surface drainage flows and seepage • consideration for mobile plant and equipment operating within proximity of the trench; • public safety • the length of time the excavation is to remain open • All plant and equipment shall be fit-for-purpose and undergo pre-use checks. These checks

shall reflect the plant manufacturer’s requirements for this pre-use check. • Mechanical digging or excavating equipment should be flat edged where possible. • Standard Council PPE and protective headwear (hardhat) shall be worn by personnel

engaged in trenching. • Personnel shall be adequately trained and assessed for competency including appropriate

licensing for operating plant, and correct usage and fitment of associated Personal Protective Equipment (PPE). Refer to Section 9.

• Barricading (or hoarding) of at least 900mm in height shall be erected around a trench that is 1.5 metres or more in depth.

• for trenches or Excavations deeper than 1.5 metres, wall support or stabilisation (i.e. benching or shoring) is required (refer to Section 7.1)

• Confined Space Entry Procedure (HS-PRO-006) requirements as applicable a rescue plan to deal with emergencies (if applicable - typically when the Excavation is considered a confined space. Refer Section 7.1.1)

Communicate details of the JSEA to all team members involved in the work. Prior to commencing work, each individual team member should conduct a personal risk assessment (Take 5) to identify and discuss any uncontrolled hazards with supervisor.



7. DURING TRENCHING AND EXCAVATION If underground services are indicated within 1 metre of a proposed Excavation, a cable locator and Hydro Excavation (Vacuum Excavation) is to be used to determine the exact location of the services prior to mechanical Excavation being permitted. Careful hand-digging should be undertaken to confirm the depth and type of underground services. Only insulated probes shall be used to locate underground services. Once all underground services are located, clearly mark the location on the surface. Record the information and ensure that all personnel involved in the trenching works are made aware of the location, depth and type of services in the vicinity of the works. Where possible isolate the underground services prior to commencing trenching or Excavation. Combustion engines shall not be in or adjacent to trenches or Excavations where there is a likelihood of the build-up of exhaust gases. Maintain the 3 metre exclusion zone (separation distance) with all overhead services while operating plant for trenching and Excavation refer to the Working On or Near Energised Electrical Installation Procedure (HS-PRO-004) for details. Trenches or Excavations greater than 1.5 metre in depth are required to be shored, benched or alternatively the side of the trench battered back at a slope of no greater than 45° to prevent trench collapse. (Refer Section 7.1) In some ground conditions (i.e. soft soils), this treatment should be applied at depths less than 1.5 metre to avoid collapse. Written approval to vary the benching and battering requirements should be obtained from a Geo Technical Engineer. The approval must be kept on site at all times. Consideration shall be given to preventing risk from the collapse of another structure such as an adjoining building or road with appropriate retention measures implemented. A Geo Technical Engineer should be consulted for further instruction prior to commencement of work. Each bench cut into the side of the Excavation or trench must be no higher than it is wide, unless a Geo Technical Engineer has approved a greater height in writing. Safe access is to be maintained for all persons in the trench. Where access ladders are provided for access they are to extend 1 metre above ground and be no more than 9 metres apart in the area of the trench where work will be carried out. Ladders must be used for accessing any trench deeper than 1.5 metres. If there is a risk of electrical services being active within a trench, fibreglass ladders shall be used. While the trench or Excavation is open it must be examined regularly by the works Supervisor to ensure that the Excavation and the control measures are stable and intact. Inspections should be conducted and documented on the work permit. Particular focus should be given to monitoring seeping, pooling or running water in the vicinity of trenches or Excavations.



Excavated material and loads near excavations While the trench or Excavation is open an internal exclusion zone shall be established to prevent the risk of collapse. This separation distance is determined by the zone of influence and applies for the safe movement of vehicles, plant and personnel, and for the storage of excavated material, tools and equipment. This distance should be at least 1 metre. The figures below show examples of:

• an excavation with shoring that has been designed to carry vehicle and material loads. This may be required where there is limited space around the excavation for vehicle movement and /or material storage

• an excavation with shoring that has been designed only to carry the load of the excavated faces and the related zone of influence.



Special Considerations Regarding Excavations Deeper Than 1.5m Where there is an intention to conduct work that will involve a person entering an Excavation greater than 1.5m in depth, at least one of the following control measures shall be used:

• Shoring of all sides; and or • Benching of all sides; and or • Battering of all sides; and or • A combination of the above methods may be used provided that all sides of the Excavation

are dealt with If these control methods are not used, the Excavation is considered unstable and workers must not enter the Excavation. If it is absolutely necessary to enter an Excavation deeper than 1.5m without correctly battering, shoring or benching, a Competent Person must approve, in writing, all sides of the trench as safe from collapse. This approval must specify the length of time that approval lasts and state the natural occurrences that could affect the stability of the trench with emergency planning protocols in place and on standby in accordance with Section 11. If a trench is not shored, benched or battered, and something occurs that could affect the stability of the trench (e.g. water seepage, subsidence or cracking), work in the trench must stop immediately and not restart, other than to shore, bench or batter the trench, until:

• a geotechnical engineer has inspected the trench and approved, in writing, the trench as safe to enter; or

• all sides of the trench have been: o Shored by shielding or another way; or o Benched; or o Battered

7.2.1. Trenching and Excavation Work Permit and Emergency Planning For trenching or Excavation works greater than 1.5m deep, a Trenching and Excavation Permit (HS-FRM-003) must be completed and approved by the task Supervisor. The site supervisor must ensure a documented emergency plan dealing with possible unexpected incidents such as ground slip, flooding, gas leaks and the rescue of workers from an Excavation have been discussed, agreed upon and recorded on the JSEA. Emergency rescue equipment identified on the JSEA (listed in Appendix 2) must be available on stand-by, fit for purpose and readily accessible in the event of an emergency.

7.2.2. Confined Space Entry Where personnel are required to enter a Trench or Excavation that is greater than 1.5m deep, the requirements of the Confined Space Entry Procedure (HS-PRO-006) apply. An exemption may be granted if a specific risk assessment is conducted that determines the risk to be minimal and an exemption is approved in writing by the relevant Branch Manager.

7.2.3. Benching and Battering 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. Benching is used to reduce the height of the vertical wall of an Excavation by cutting a series of steps. Benching must not be higher than it is wide and no vertical face exceeding 1.5 metres, unless a geo-technical engineer has approved a greater height, in writing. 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 at angle not exceeding 45°. Refer Excavation Work Code of Practice 2013



When benching or battering the walls of an Excavation, an angle of repose of 45° must not be exceeded unless certified, in writing, by a geo-technical engineer. In some circumstances, it may be appropriate to use a combination of the two methods on an Excavation.

7.2.4. Shoring It is a legal requirement that where necessary, all trenches and Excavations must be adequately shored or supported 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. The installation and removal of shoring should take place from outside an Excavation. Never position moving plant or place/ stack materials near the edge of any Excavation work so as to endanger persons working below. Shoring the face of an Excavation should proceed as the 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 unsupported. Shoring may include any suitable system of temporary supports and sheeting material used to maintain the stability of the sides of an Excavation.

Benching

Battering

Combination of Benching

and Battering



Types of shoring and support systems include, but are not limited to: • Sacrificial sets - stay in the ground indefinitely, may be timber, concrete etc. These must

be marked up on underground drawings. • Soldier sets - timber, steel proprietary • Full timber systems • Trench supports (e.g. shields, boxes or cages etc.) • Sheet piling • Precast panels • Diaphragm walls • Rock bolts and ground anchors • Caissons • Sand bag (sand cement mix) • Hydraulic systems • Soil nails, shotcrete, etc. • Pneumatic systems

Sheeting or timber shall only be used to shore the Excavation if a Geo-Technical Engineer assesses the soil loading (and hence shoring requirements) and a structural engineer assesses the shoring to assert that the shoring meets that soil loading requirement.

Hydraulic shoring (soldier

set style)

Steel Sheet Piling



If shoring is used and it is commercially manufactured shielding, it must be: • Designed by an engineer for the purpose for which it is to be used; and • Erected in accordance with the instructions, if any, of its manufacturer or supplier.

When removing shoring, the support 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 support system. Always carefully consider the risks of removing shoring and control the removal in such a manner to ensure that the Excavation does not collapse. To prevent injury to workers, no person is to be in the Excavation when removing shoring. Refer Excavation Work Code of Practice 2013.

Timber Soldier Sets



8. FOLLOWING TRENCHING AND EXCAVATION After the completion of work the trench or Excavation is to be back-filled as soon as possible. As part of rehabilitating the worksite a final review is to be undertaken to ensure that there are no physical hazards evident (i.e. prevention of slips, trips and falls) as a result of the trenching or Excavation. On completion of the trenching or Excavation and when the site is made safe, the Trenching and Excavation Permit can be closed. All other applicable work permits which were issued as part of the trenching and Excavation task shall now be closed. All closed work permits shall be given to the job supervisor. All records pertaining to the trenching and Excavation task shall be retained for 28 days (Unless in the unlikely event of an incident, shall be retained for 2 years).

9. TRAINING & COMPETENCE Initial Trenching and Excavation training is to be completed by all workers prior to any site works being undertaken with refresher training to be completed at intervals not exceeding two (2) years. Training records shall be retained for a period of seven (7) years. Trenching and Excavation training shall include training for emergencies, including trench collapse and if contact is made with underground services such as electricity, gas or sewerage. All trenching and Excavation training is to be conducted by a Registered Training Organisation (RTO). All personnel who may be required to enter a trench or Excavation to provide first aid must be trained in Cardio Pulmonary Resuscitation (CPR) and also hold a current senior first aid certificate. A construction industry white card (Construction Induction Training Card (CITC) - Course Code: CPCCOHS1001A) must be held by all workers involved in trenching and Excavation works.

10. EMERGENCY RESCUE Prior to accessing a trench or Excavation, all rescue equipment must be inspected and deployed in readiness for use (Refer to Appendix 2 - Register of Trenching and Excavation Emergency Rescue Equipment). Should an emergency rescue be required, a competent person is to control and lead the process, assessing the extent of the emergency situation (including an assessment of any injuries that may have occurred) and determining the most appropriate rescue strategy. The extent of the emergency and the nature of the injuries will determine the rescue options; for example; if the employee has become trapped or engulfed then priority is to be given to facilitating their immediate rescue, however if an employee has fallen and incurred head or spinal injuries and has sufficient oxygen then the rescue process should be managed by the emergency services. Prior to entering the trench or Excavation, the competent person must nominate assistance from other trained personnel, specifically requiring them to support the rescue process.

11. MEDICAL ASSESSMENT No specific medical assessments are required for trenching and Excavation. Provisions for Fitness for Work apply.



12. MONITORING AND REVIEW To ensure compliance to this procedure formal audits should be initiated. The audit should be completed by an assigned person with the audit comprising an assessment of the systems and processes for Trenching and Excavations and a field observation component to verify the application of these requirements. Determination is to be made as to the work groups’ level of compliance to the requirements of this procedure. This procedure is to be reviewed every 5 years, or earlier if:

• there is an identified risk to business; • a significant electrical safety event occurs; • incident investigation or audit results show that application of the procedure fails to deliver

the required outcomes; • there are changes in associated legislation; • there is evidence that the procedure is not having a positive impact on safety-related

performance indicators; or • there is a change to the Construction and High Risk Work Directive (HS-DIR-005)

Any incidents resulting from Trenching or Excavation work shall be thoroughly investigated in accordance with the Incident Management Procedure (HS-PRO-034)

13. ASSOCIATED DOCUMENTS • Construction and High Risk Work Directive (HS-DIR-002) • Trenching and Excavation Permit (HS-FRM-003) • Trenching and Excavation Safe Work Method Statement (HS-SWMS-003) • Confined Space Entry Procedure (HS-PRO-006) • Working at Heights Procedure (HS-PRO-002) • Working On or Near Energised Electrical Installation Procedure (HS-PRO-004) • Lockout and Tagout Procedure (HS-PRO-019) • Incident Management Procedure (HS-PRO-034) • Authorised Person; Permission to work near overhead or underground electric lines

(Energex Form 3004_12 05 14) • People Managers Toolkit – Trenching and Excavations

Toolkits provide practical guidance, useful tools and information for people managers to effectively manage the risks associated with staff undertaking or around Trenching and Excavations.

14. LEGISLATIVE AND OTHER REFERENCES • Work Health and Safety Act 2011 • Work Health and Safety Regulation 2011 • Electrical Safety Act 2002 (Qld) • Electrical safety Regulation 2013 (Qld) • Environmental Protection Act 1994 (Qld) • Environmental Protection Regulation 2008 (Qld) • Transport Operations (Road Use Management) Act 1995 • Excavation Work Code of Practice 2013 • Managing the Risk of Falls at Workplaces Code of Practice 2011



15. DOCUMENT CONTROL Approval Date Position Name

Edited By: 27/02/2017 Health and Safety Advisor Jennifer Neville

Document Owner: 27/02/2017 Health and Safety Program Leader Simon Faber

Approved by: 27/02/2017 People and Culture Manager Mark Goldsworthy

Revision # Date Section(s) Changed Brief Description of Change

1.0 27/07/2015 All New document



APPENDIX 1- Register Of Trenching and Excavation Equipment

Trenching and Excavation

Reference Inspection interval

Earthmoving equipment / mobile plant

Guide to Machinery & Equipment Safety QLD 2015

6 monthly certification With pre-use test

Hydro vacuum 6 monthly certification With pre-use test

Gas monitor AS 61779 6 monthly certification With pre-use test

Compressed air cylinders AS 3848 5 years With pre-use visual inspection

Dry Chemical Fire extinguisher

AS 1851 6 monthly With pre-use visual inspection

Hardhat & Face Shield (as required)

AS/NZS 1800 / 18001/ 1337 3 years With pre-use visual inspection

Barricades and Signage AS 1319 / AS 4687 3 years With pre-use visual inspection

First Aid kit First Aid in the Workplace COP Feb2016

Replenish stock as required

APPENDIX 2 - Register of Trenching and Excavation Emergency Rescue Equipment

Safety harnesses AS/NZS 1891 6 monthly certification With pre-use visual inspection

Retractable lanyard 6 monthly certification With pre-use visual inspection

Self-retracting life line 6 monthly certification With pre-use visual inspection

Davit arm AS 1418 / AS2625 3 monthly certification With pre-use visual inspection

Tripod 3 monthly certification With pre-use visual inspection

Self-contained breathing apparatus (Primary and emergency)

AS/NZS 1715 / 1716 6 monthly With pre-use visual inspection

Intrinsically safe torch IEC Ex pre-use visual inspection UHF radios (minimum of two) AS 4365 pre-use test

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