With the exclusion of previously cleared greenfield areas where there is no chance of striking underground services, an effort should be made to ensure all areas to be excavated, undisturbed or finished grade will be “swept” with locating instrumentation and locations of underground services will be clearly marked on the surface (paint, flags, stakes, etc.) prior to commencing the excavation.
Current “as-builts” of the area, as well as underground locating techniques, will be used to locate
underground services and marked up copies of the as-built drawings which should be attached to
the excavation permit. Some clients may or may not request for an excavation permit.
All underground services in the excavation limits and within 2 m (6 ft.) of the proposed excavation
limits will be exposed by daylighting; i.e., hand excavating (shovels only) or hydrovacing at all
junctions and intervals not exceeding 50 m. Where services are identified on as-built drawings as
being within 2 m of the excavation limit, and cannot be detected by locating instrumentation, the
daylighting requirement will increase to 5 m minimum clearance.
When hand excavating within 2 m (6 ft.) of an existing underground service, the service shall be
hand exposed by a competent worker. Care shall be taken not to use tools that could damage the
Exposed cables/piping shall be supported.
Underground services that are undermined in the excavating operation shall be adequately supported to ensure the undermining does not create a hazard to personnel or the service due to
flexing or fracture. Excavations and trenches deeper than 1.2 m (4 ft.) and no greater than 3 m (10 ft.) deep that require entry by workers must:
- Be sloped to not less than 45° from the vertical, or
- Have temporary structures installed that are of sufficient strength to prevent the walls of
the excavation from caving in or otherwise moving into the excavation and thus protect the worker.
To be continued…….
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