UTILITY POLE COLLAPSE Type of Incident: Fatal Date of Incident: September 10, 2011

Transcription

1 UTILITY POLE COLLAPSE Type of Incident: Fatal Date of Incident: September 10,

2 File: F TABLE OF CONTENTS SECTION TITLE PAGE NUMBER 1.0 DATE AND TIME OF INCIDENT NAME & ADDRESS OF PRINCIPAL PARTIES Owner Prime Contractor Employer(s) Contractor(s) Supplier(s) Workers(s) Others 3.0 DESCRIPTION OF PRINCIPAL PARTIES Employers Worker LOCATION OF INCIDENT EQUIPMENT, MATERIAL AND OBSERVATIONS Equipment and Material Observations NARRATIVE DESCRIPTION OF INCIDENT ANALYSIS Direct Cause Contributing Factors FOLLOW-UP/ ACTION TAKEN Human Services, Occupational Health and Safety Industry Additional Measures SIGNATURES ATTACHMENTS 10

3 File: F SECTION 1.0 DATE AND TIME OF INCIDENT 1.1 September 10, 2011 at approximately 3:35 p.m. SECTION Owner(s) Altalink, L.P rd Avenue SE Calgary, Alberta, T2A 7W7 2.2 Prime Contractor Altalink, L.P rd Avenue SE Calgary, Alberta, T2A 7W7 2.3 Employer(s) Galbraith Power (BC) Inc Broadway Street Port Coquitlam, BC V3C 2M Empirica Energy Inc Suite C, 16 th Avenue North Lethbridge, AB T1H 5J6 2.4 Contractor(s) Greely Rock Ltd. Box 2072 Revelstoke, BC V0E 2S0 2.5 Supplier(s) Poletec Industries Ltee./Ltd Rue Henault Montreal Nord, Quebec H1G 5R4 2.6 Worker(s) NAME AND ADDRESS OF PRINCIPAL PARTIES Evan Horkoff, Galbraith Power (BC) Inc., Apprentice Lineman 177 Silverado Range Cove SW Calgary, AB, T2X 0E1

4 File: F Others RCMP Crowsnest Pass Detachment SECTION 3.0 DESCRIPTION OF PRINCIPAL PARTIES 3.1 Altalink L.P., an Alberta based large power Transmission Company with more than 600 workers, owns, operates and maintains power lines and was the prime contractor at the site. Altalink L.P. contracted Empirica Energy Inc. to refurbish part of the 170 L power line including Structure Galbraith Power (BC) Inc. was the employer of the deceased worker. On September 9, 2011, the day before the incident, Empirica Energy Inc. and Galbraith Power (BC) Inc. were amalgamated under the name Galbraith Power (BC) Inc. The amalgamated Corporation was registered with the British Columbia Registry Services on October 1, On December 16, 2011, Galbraith Power (BC) Inc. changed its name to Rokstad Power Corporation in Alberta. 3.3 Prior to restructuring, Empirica Energy Inc. hired a small company, Greely Rock Ltd. to provide safe access to the sites (scaling) and to drill holes into the rocks to facilitate the installation of anchors. Greely Rock Ltd., worked under the civil division of Empirica Energy Inc. 3.4 Poletec Industries Ltee./Ltd., was the supplier of the Tri-Anchor pole mount system designed to secure utility poles in rocky terrain. 3.5 The fatally injured worker (Evan Horkoff) was a first year lineman apprentice. He started his apprenticeship on August 2, SECTION 4.0 LOCATION OF INCIDENT The incident occurred at a location approximately 1 km east of Blairmore, Alberta, at Structure 29 of power line 170 L. Structure 29 was located in rocky, mountainous terrain above Highway 3 (Refer to Attachment A-Map and Attachment B- Photographs 1, 2, 3 and 4). SECTION Equipment and Material EQUIPMENT, MATERIAL AND OBSERVATIONS Two wooden poles were part of a temporary structure built to facilitate the removal of conductors and cross braces from the existing power line poles that were scheduled for replacement. The conductors had been de-energized.

5 File: F The temporary wooden pole involved in the incident was approximately 17 meters high and weighed 880 kilograms. There was a 3.1 meter long sling attached to the pole near the top end. A No.9 Tri-Anchor pole mount system was used to secure the temporary wooden poles to the ground. Galbraith Power (BC) Inc. installed two guy wires on each of the two temporary poles and a bridal guy wire between the two poles to provide structural stability The No.9 Tri-Anchor pole mount system was designed to be used in solid rock. The system consisted of modules with hollow metal tubes (sleeves) that, when bolted together form a tight collar encircling the butt of the pole. According to the manufacturer s specifications, rock anchors extend through the sleeves and into.61 meter deep holes pre-drilled into rock. The anchors have expansion shells on the bottom ends which are inserted into holes drilled into the rock. When the nuts on the top of the anchors are tightened, the expansion shells expand, to secure the anchors. The number of modules required depends on the diameter of the pole butt (Refer to Attachment C- Tri-Anchor manufacturer s specifications) The pole mount system at the location did not have Tri-Anchor anchors. Instead, it was secured to the rock by No.8 DYWIDAG thread bars inserted into 6 foot deep holes drilled into the rock. The collar was made up of 4 modules. Four DYWIDAG thread bars were inserted through the hollow metal tubes and into the holes. There were no expansion shells at the bottom of the DYWIDAG thread bars. Each DYWIDAG thread bar had a nut on the top end of the module. In addition two of the thread bars had a bolt at the bottom end. There was no grouting (cementing) of the DYWIDAG thread bars in to the ground (Refer to Attachment B- Photographs 5). 5.2 Observations Environment Canada weather records for Crowsnest area show that the temperature at the time of the incident was approximately 26 C with a wind speed of 20 km/h. The location where the pole butt was located had considerable overburden consisting of soil and rock fragments Galbraith Power (BC) Inc. personnel had previous experience in the use of the Tri- Anchor pole mount system but Altalink L.P. was not familiar with the system There were no engineering specifications available for the temporary wooden pole structures installed with a modified Tri-Anchor pole mount system Galbraith Power (BC) Inc. personnel at the site had determined that the terrain at the site of the structure 29 was not solid enough to use the 0.61 meter long anchors of the Tri-Anchor pole mount system. Instead, Galbraith Power (BC) Inc. decided to drill 1.83 meter deep holes and to use #8 DYWIDAG thread bars as anchors to the Tri-

6 File: F Anchor collars. SECTION 6.0 NARRATIVE DESCRIPTION OF THE INCIDENT 6.1 On August 17, 2011, Greely Rock drillers (Josh Veres, Bill Ethier) drilled 4 holes for each of the two temporary poles to a depth of 1.83 meters at locations marked by Empirica Energy Inc. personnel at the site of the structure 29. The holes were drilled using a Tri-Anchor template. They inserted a #8 DYWIDAG thread bar into each hole and slid Tri-Anchor sleeves over the #8 DYWIDAG thread bar. 6.2 On September 9, 2011, Galbraith Power (BC) Inc. line crew consisting of foreman (Wayne Hanis), lineman 1 (Ron Stewart), lineman 2 (Shawn Gaudrey), lineman 3 (Darren Harvey), trade trainee (Tyler Ebenal), lineman apprentice (Evan Horkoff) and the general foreman (Nico Geelhoed) arrived on site and installed the Tri-Anchor modules over the #8 DYWIDAG thread bar to form the collar of the pole mount. The temporary wooden pole was flown into the location by helicopter and lowered into the Tri-Anchor collar. The line crew guided the pole butt into the collar and tightened the collar. Three temporary ropes attached to the pole were connected to ground anchors to provide stability to the pole. 6.3 The same procedure was repeated for the second pole. After the helicopter left, the journeyman lineman 1 (Ron Stewart) climbed the poles and attached two guy wires from each pole and connected them to ground anchors. A third guy wire, called a bridal was attached to connect the two temporary poles horizontally. The three temporary ropes attached to the pole were removed. 6.4 On September 10, 2011, the line crew (Wayne Hanis, Ron Stewart, Shawn Gaudrey, Darren Harvey, Tyler Ebenal and Evan Horkoff) returned to the site and installed work platforms (Baker boards) on the temporary poles. Working from the Baker boards, the crew proceeded to remove the existing power line. They successfully lowered the east and west conductors and removed the cross braces and rigging from the old structure. The crew installed slings on the old poles and the temporary poles to facilitate their removal. 6.5 After removing the bridal guy wire, they attempted to lower the centre conductor to the ground. The conductor came down against the west temporary pole which caused it to lean westward into the side of the mountain, partially pulling out a DYWIDAG thread bar from ground on the east side of the pole. The line crew managed to lower the centre conductor by rigging and pulling the conductor towards the east temporary pole.

7 File: F The crew cut the leaning west temporary pole above the Tri-Anchor attachment and dropped it to the ground, then flew it out to the storage yard. The old lower pole was also removed and flown away to the storage yard. The remaining guy wires on the east temporary pole were removed. 6.7 It was observed that the 3.1 meter sling attached to the temporary pole was not long enough to reach ground and allow for hook up to the helicopter for removal. With the permission of the foreman (Wayne Hanis), the apprentice (Evan Horkoff) climbed the temporary pole to connect an extension sling. He was wearing the required safety gear and was attached to the temporary pole. When the apprentice (Evan Horkoff) was close to the sling already attached to the temporary pole, it started to lean. 6.8 The temporary pole fell to the down side of the mountain, partially pinning the apprentice (Evan Horkoff), under the pole. The foreman (Wayne Hanis) and Lineman 1 (Ron Stewart) immediately climbed down to the location of the apprentice to assist him. 6.9 The foreman (Wayne Hanis) called the rescue team, the helicopter and Emergency Medical Services (EMS). The rescue team extracted the injured worker and helped move him into the helicopter. The helicopter airlifted the injured apprentice (Evan Horkoff) to an EMS vehicle that was waiting on nearby Highway 3. EMS transported the injured apprentice (Evan Horkoff) to the Blairmore hospital where he succumbed to his injuries the same day. SECTION Direct Cause ANALYSIS The apprentice (Evan Horkoff) fell to the ground when a temporary wooden pole he had climbed fell. 7.2 Contributing Factors The Tri-Anchor system was not used in accordance with the manufacturer s specifications. The surface rock at the location did not meet the manufacturer s requirements The modifications to the Tri-Anchor system as used to construct a temporary structure were not performed in accordance with specifications certified by a professional engineer. There were no engineering specifications for the erection, use and dismantling of the temporary pole structure The #8 DYWIDAG thread bars used as anchors were not grouted in or anchored to the rock. There was no procedure in place to ensure that #8 DYWIDAG thread bars were adequately anchored to the rock to support the temporary poles.

8 File: F The line crew was not aware that the #8 DYWIDAG thread bars were not adequately anchored to the rock. Some bolts on the top end of the modules tightened due to the presence of bolts at the bottom end The guy wires holding the pole had been removed prior to the incident The sling attached to the pole was not long enough to reach the ground, requiring the attachment of an extension sling. SECTION 8.0 FOLLOW-UP/ ACTION TAKEN 8.1 Human Services, Occupational Health and Safety On September 10, 2011, Occupational Health and Safety (OHS) received an incident notification. Occupational Health and Safety Officers responded to the scene immediately and commenced an incident investigation OHS issued an order requiring the prime contractor to conduct an incident investigation and prepare a report OHS issued a Demand for documents related to the incident OHS issued a stop work order for work activities requiring workers to climb poles supported by Tri-Anchor systems until the cause for the incident was determined OHS hired a consulting geotechnical engineer to evaluate the anchoring system used at the location to secure the temporary pole. 8.2 Industry On September 10, 2011 following the incident, Galbraith Power (BC) Inc. voluntarily stopped work on the 170L power line prior to the arrival of OHS Galbraith Power (BC) Inc. stopped using the Tri-Anchor pole mount system The prime contractor conducted an incident investigation and submitted a report to OHS The employer and prime contractor complied with all orders issued by OHS.

9 8.3 Additional Measures File: F When Tri-Anchors are to be utilized, the prime contractor, Altalink, L.P. required all contractors to obtain an assessment of conditions by a professional engineer to ensure sufficient anchoring. In addition, all contractor personnel involved in the installation, use or removal of temporary poles and the Tri-Anchor System are required to be trained on the procedures and manufacturer s specifications for their installation, use and removal. SECTION 9.0 SIGNATURES Original Report Signed October 15, 2014 Lead Investigator Date Original Report Signed October 15, 2014 Reviewer Date Original Report Signed November 17, 2014 Director Investigations Date SECTION 10.0 ATTACHMENTS: Attachment A - Map Attachment B - Photographs Attachment C - Tri-Anchor manufacturer s specifications

10 GALBRAITH POWER (BC) INC. File: F Attachment A Map Map Arrow shows the location of the incident, approximately 1 km east of Blairmore, Alberta.

11 GALBRAITH POWER (BC) INC. File: F Attachment B Photograph 1 of 5 Photograph 1 Shows the view of the incident site from Highway 3. Arrow shows the fallen temporary pole.

12 GALBRAITH POWER (BC) INC. File: F Attachment B Photograph 2 of 5 Photograph 2 Shows an aerial view of the incident site.

13 GALBRAITH POWER (BC) INC. File: F Attachment B Photograph 3 of Photograph 3 Shows the site of the incident. 1) Old permanent pole (west) 2) DYWIDAG thread bars on the fallen pole pulled out from the ground 3) Tri-anchor collar 4) Stump of the old permanent pole (east) 5) Butt section of the temporary pole (west) 6) Tri-anchor collar on the temporary pole (west)

14 GALBRAITH POWER (BC) INC. File: F Attachment B Photograph 4 of 5 Photograph 4 Shows the fallen temporary pole on the side of the mountain.

15 GALBRAITH POWER (BC) INC. File: F Attachment B Photograph 5 of Photograph 5 Shows the butt section of the temporary fallen pole. 1) Pulled out #8 DYWIDAG thread bars 2) Tri-anchor collar

16 Attachment C Tri-anchor manufacturer s specifications

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