Report No-F-OHS-096744-D9370

November 2018

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Investigation Report

Worker Fatally Crushed by Excavator

October 23, 2015

F-OHS-096744-D9370Alberta

Final Report

Labour

Occupational Health and Safety

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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.

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Occupational Health and Safety

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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.

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Occupational Health and Safety

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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

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Occupational Health and Safety

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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.

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Occupational Health and Safety

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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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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.

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Occupational Health and Safety

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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.

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Occupational Health and Safety

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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.

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Occupational Health and Safety

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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