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Report No-F-OHS-096744-D9370
November 2018
Page 1 of 10
Investigation Report
Worker Fatally Crushed by Excavator
October 23, 2015
F-OHS-096744-D9370Alberta
Final Report
Labour
Occupational Health and Safety
Page 2 of 10
The contents of this report This document reports Occupational Health and Safety’s investigation of a fatal accident in
October 2015. It begins with a short summary of what happened. The rest of the report covers
this same information in greater detail.
Incident summary Two pipe layers, employed by an excavation contractor, were installing new storm water lines in
northwest (NW) Calgary. The workers were preparing a concrete manhole barrel for temporary
installation when the project foreman accessed and activated the hydraulic excavator parked
beside the pipe layers’ work area. The foreman turned the upper structure of the excavator to the
left causing the excavator counterweight to strike the pipe layer who was cutting the manhole
barrel. The pipe layer was fatally injured when pinned between the counterweight of the
excavator and the manhole barrel.
Background information The City of Calgary Water Resources Department is responsible for providing drinking water
and treating wastewater for the City of Calgary as well as maintaining the storm water drainage
system. This department is also responsible for the construction, maintenance and up-grading of
the water and wastewater systems in the City of Calgary.
In 2015, the City of Calgary Water Resources – Infrastructure Delivery issued a tender for the
upgrade of services in the community of Rosemont in NW Calgary (Rosemont Community
Drainage Improvements).
Bluebird Contracting Services Ltd. is a full service earthworks company that is a division of the
Trotter & Morton Group of Companies. Bluebird Contracting Services Ltd. specializes in
earthworks, demolition, underground services, asphalt paving and rail construction and
maintenance.
Bluebird Contracting Services Ltd. was awarded the City of Calgary Water Resources –
Infrastructure Delivery contract for the Rosemont Community Drainage Improvements Project
and assumed the role of prime contractor for the duration of the project as per contractual
agreement.
Bluebird Contracting Services Ltd. employed both of the pipe layers, the designated equipment
operator, and the foreman. Bluebird Contracting Services Ltd. also owned the Hitachi ZAXIS
350LC-5N hydraulic excavator involved in the incident.
F-OHS-096744-D9370Alberta
Final Report
Labour
Occupational Health and Safety
Page 3 of 10
The foreman employed by Bluebird Contracting Services Ltd. on the Rosemont Community
Drainage Improvements Project had been working in the construction industry for approximately
30 years as a pipe layer, equipment operator and foreman. The foreman had been employed by
Bluebird Contracting Services Ltd. for approximately three months prior to the incident.
Equipment and materials Hitachi ZAXIS 350LC-5N Hydraulic Excavator
The Hitachi ZAXIS 350LC-5N hydraulic excavator involved in the incident was a medium-sized
excavator that was owned and operated by Bluebird Contracting Services Ltd. The unit was
being used both for excavation and backfilling as well as for material handling and positioning.
At the time of the incident, the excavator had been parked adjacent to a recently dug trench as a
form of temporary traffic barrier both for the excavation for a new section of storm water lines
which ran parallel along the South side of Rosehill Drive and as a measure of protection for the
pipe layers working in the area. The unit was parked adjacent to a concrete manhole barrel
which was located near the right rear corner of the counterweight on the excavator.
The Hitachi ZAXIS 350LC-5N hydraulic excavator had a rear (tail) swing radius of 3.39 metres
and was equipped with left and right front mirrors for the operator to see the back corners of the
unit. The ZAXIS excavator unit was not equipped with a rear-view camera at the time of
incident.
Hydraulic excavators have an undercarriage composed of the chassis, turntable and a pair of
track shoe assemblies (caterpillar tracks) mounted on track frames which enables movement
forward and backward. In addition, the upper structure (consisting of the cab, engine
compartment and boom assembly) sit on a turret which enables the operator to move 360 degrees
around a vertical axis. During an inspection commissioned by Occupational Health and Safety
of the Hitachi ZAXIS 350LC-5N hydraulic excavator, the average rotational speed of the
carriage was found to be: 18 seconds in IDLE and 5.9 seconds in HIGH for a single revolution
around the vertical axis.
F-OHS-096744-D9370Alberta
Final Report
Labour
Occupational Health and Safety
Page 4 of 10
Figure 1. Profile view of the HITACHI ZAXIS 350-LC-5N hydraulic excavator showing
components.
Dashed line – approximate location of vertical axis
Upper Structure: Arrows A to D
A - Boom and Arm Assembly
B - Operator Cab
C - Counterweight
D - Engine Compartment
E - Undercarriage (Turntable, Track shoe assembly and Track frame)
A
B
C
D
E
F-OHS-096744-D9370Alberta
Final Report
Labour
Occupational Health and Safety
Page 5 of 10
INLAND Pipe MH 1.8 Ø Cement Manhole Barrel
Dimensions: 1800 millimetres (mm) x 2.0 metres (m)
Volume: 5255 litres (L)/barrel
Weight: approximately 6140 kilograms (kg) (according to manufacturer documentation)
Figure 2. Manhole barrel that was being cut by the deceased worker prior to the incident.
F-OHS-096744-D9370Alberta
Final Report
Labour
Occupational Health and Safety
Page 6 of 10
Sequence of events The day of the incident, October 23 2015, Bluebird Contracting Services Ltd. was installing new
storm water infrastructure as part of the City of Calgary Rosemont Storm Water Improvement
Project. The worksite was located at the “Tee” intersection of Cambrian Drive/10 Street NW
and Rosehill Drive NW in Calgary and was part of the City of Calgary – Rosemont Storm Water
Improvement Project.
Figure 3. Location of incident October 23, 2015
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Final Report
Labour
Occupational Health and Safety
Page 7 of 10
Figure 4. Aerial view from Google Maps of Rosehill Drive and 10 Street NW with work area
denoted in circle.
At the time of incident, the majority of the work crew was at lunch, while two pipe layers
continued to work, preparing concrete sections for installation. The two workers were on
Rosehill Drive, with one pipe layer (deceased worker) cutting a section out of a previously
damaged manhole barrel in order to facilitate continuation of pipe installation while a
replacement manhole barrel was brought to site. The designated excavator operator for the site
had parked the ZAXIS 350 LC-5N excavator along a recently dug trench parallel to Rosehill
Drive in order to provide a temporary barrier for the trench and the two pipe layers. The
excavator was positioned adjacent to the manhole barrel. The excavator operator had advised the
two pipe layers that the excavator was shut off and would not be in operation as the operator was
going for lunch.
F-OHS-096744-D9370Alberta
Final Report
Labour
Occupational Health and Safety
Page 8 of 10
The pipe layers had been alternating between cutting the manhole barrel and a length of pipe in
preparation for installation, but they had stopped cutting the pipe section as the pipe had to be
repositioned by the excavator in order for the workers to continue. As a result, the workers were
working on the manhole barrel while they waited for the excavator operator to return.
While the one pipe layer (deceased worker) was cutting the manhole barrel, the foreman for
Bluebird Contracting Services Ltd. entered the pipe layers’ work area and spoke to the pipe
layers behind the excavator, near the manhole barrel. At the time, the pipe layers indicated that
they were working on the manhole barrel while they waited for the excavator operator to return
from lunch in order to reposition the pipe section they were initially cutting. The two pipe layers
indicated that the pipe section did need to be moved but did not request that the pipe section be
moved during the discussion with the foreman since they were working on the manhole barrel.
The one pipe layer (deceased worker) returned to cutting the manhole barrel, and the other pipe
layer was speaking to the day-lighting operator from Badger Daylighting Ltd. when the foreman
entered the ZAXIS 350 LC-5N excavator. The foreman started the unit and rotated the carriage
to the left causing the counterweight to strike the worker cutting the manhole barrel with enough
force to cause the barrel, which weighed approximately 6140 kg, to tip. The worker was pinned
between the counterweight and the barrel and sustained fatal injuries.
F-OHS-096744-D9370Alberta
Final Report
Labour
Occupational Health and Safety
Page 9 of 10
Completion A review for enforcement action was completed on June 1, 2016, and it was determined that the
file would be referred to Alberta Justice for review. The entire file was sent to Alberta Justice on
July 4, 2016. Charges were laid on October 10, 2017.
On November 5, 2018, Mark Dumont (foreman) pled guilty to the charge that he, being a worker
engaged in an occupation, did fail to take reasonable care to protect the health and safety of
another worker present while the other worker was working, contrary to Section 2(2)(a) of the
Occupational Health and Safety Act. Mark Dumont was ordered, under Occupational Health
and Safety Act Section 75, to pay $75,000 to fund an Alberta Construction Safety Association
program to promote safe work with powered mobile equipment. Additionally, he was placed on
12 months of probation like conditions. The remaining charges against Mr. Dumont were
withdrawn. All charges against Bluebird Contracting Services Ltd. were withdrawn.
This investigation was closed on November 8, 2018.
F-OHS-096744-D9370Alberta
Final Report
Labour
Occupational Health and Safety
Page 10 of 10
Signatures
ORIGINAL REPORT SIGNED November 8, 2018
Lead Investigator Date
ORIGINAL REPORT SIGNED November 15, 2018
Manager Date
ORIGINAL REPORT SIGNED January 10, 2019
Director Date
