8.1 OVERVIEW
Purpose To eliminate the risk of fatalities and reduce the potential for injuries and
incidents when working in and around excavations and trenches.
Scope This protocol applies when creating and / or working in and around
excavations and trenches.
Incident causes Excavations and trenches can lead to hazardous situations. The most
frequent root causes and contributing factors for incidents involving excavations and trenches have included:
n Failure to identify the location(s) of buried utilities.
n Failure to properly cut back or shore walls, resulting in collapse and
entrapment.
n Equipment operating too close to the edge of an excavation or trench. n Spoils piles left too close to the edge, resulting in collapse and entrapment. n Falls into the excavation from unprotected edges.
n Inadequate means of egress.
n Failure to monitor hazardous atmospheres
8.2 REQUIREMENTS
Legislation Obey all prevailing legislated requirements, applicable OH&S legislation,
standards and industry codes of practice when creating and / or working in and around excavations and trenches.
Depth requirements A professional engineer shall certify any excavation and / or shoring
system that falls outside of the requirements of this protocol.
Depth / Length Requirement
0.0 - 1.2 m No cut back, shoring or barricading required. 1.2 - 1.8 m Cut back and / or shoring required.
1.8 – 6.0 m Perimeter protected to prevent falls into the excavation. See Protocol 5 – Working at Heights. > 6.0 m Assessed and approved by a Professional Engineer (in
Risk assessment Include excavation work in the risk register.
Document a JSA before the commencement of excavation work and any time that the scope of work changes. Document and consider the following:
n Identification of underground utilities and planned methodology for
exposure (daylighting).
n Identification of overhead utilities and protective measures. n Equipment requirements and means of access / egress. n Cut back and / or shoring system details.
n Spoils removal and stockpile methods, including placement locations. n Personnel access and egress routes and associated ladders and / or stairs. n Influence of weather on the condition of the excavation (i.e.
deteriorating face or cut back, accumulation of water etc.).
n Evaluation of potential air quality and hazardous materials issues
within the excavation (i.e. accumulation of equipment fumes, petrochemical and / or groundwater contamination, biological hazards, etc.).
n Surface and groundwater locations.
n Proximity and physical conditions of adjacent structures and
vehicular traffic.
Excavation Develop, implement and review annually written excavation procedures.
procedures Document and address the following:
n Daily inspection of excavations and trenches (or as conditions change). n Flagging, marking, safeguards or other appropriate and effective
means to ensure that personnel are made aware of the excavation.
n Accumulation of water may pose a hazard to personnel required to
enter an excavation or trench. De-watering or alternate controls must be in place prior to entry.
n Use of spotter personnel whenever mechanical excavation work
comes within 1 meter of a buried utility. Manually excavate or hydrovac within 1 meter of the underground utility until it is adequately exposed (daylighted).
n Barricading is required to protect personnel exposed to unprotected
excavations greater than 1.2 meters (4’) deep and over 6 meters (20’) in length.
n Every excavation shall have a safe means of access / egress located
every 6 meters (20’),
Critical Risk Control Protocols
Safe work Use a safe work permit for all excavations deeper than 1.2 meters (4').
permit
Ensure that locates and as-built drawings are readily available for review by equipment operators and spotter personnel.
Ensure that all personnel involved in excavating and exposing underground utilities review and sign the safe work permit before commencing work.
Lifting Perform all lifting operations (i.e. placement of shoring cage in excavation,
operations lowering of rebar, pipes, etc. into the excavation / trench) in accordance
with Protocol 6 – Lifting Operations.
Barricading Protect or cover any excavation or trench, which crosses a site or public
roadway or sidewalk with barricades and / or plates. Design and approve barricades and / or plates for their use (i.e. load consideration for vehicle and / or pedestrian traffic).
Spoil piles Keep all spoil piles at least 1 meter (3.3') from the edge of any excavation.
Underground Identify and protect from damage all underground utilities within the
utilities excavation or trench area. Release of energy in accordance with
Protocol 4 – De-Energization.
Ensure that only appropriately competent persons act as spotters to guide equipment operators near underground utilities.
Soil Assess soil conditions and classify soil types as applicable. Stabilize soil
classification, through cut backs, shoring or a combination of both.
cut back and
shoring Inspect to ensure that shoring systems are appropriate to soil conditions
and work activities. Follow the design and construction plans for all excavations. When using shotcrete walls as the principle method of shoring, cure time must be respected to ensure sufficient strength is developed before workers enter the vicinity.
Ensure that an engineered plan is developed for any excavation next to or adjacent to an existing structure.
Type of Soil Compressive Strength
(kPa)
Cut back diagram
A: hard and compact