St. Thomas Storm Restoration: Lessons Learned
Late last year, two powerful hurricanes – Irma and Maria – carved their way across the Virgin Islands and nearby Puerto Rico before turning north. Both hurricanes left behind substantial damage to the region, including debris, flooding, communication outages, power outages, and water and food shortages. As the first deployed line crews to arrive in the region, Western Area Power Administration (WAPA) linemen were tasked by the Federal Emergency Management Agency to repair roughly 25 miles of 34.5-kV transmission lines on St. Thomas in the U.S. Virgin Islands.
In the electric utility business, it is common knowledge that energy recovery after a natural disaster can be complicated due to physical damage to the electric system and surrounding land as well as unknown hazards. Accordingly, throughout the restoration effort on St. Thomas, WAPA crews didn’t always know what they faced or the extent of the damage until after it was thoroughly evaluated. Worksite tailgate meetings and job briefings were often held several times a day because issues that affected both the scope of work and the safety of employees had to be mitigated before continuing the work.
WAPA linemen encountered numerous hazards while working to restore power on St. Thomas, including:
- Hazardous driving conditions due to narrow and slippery roadways, and driving on the left side of the road.
- No power to traffic lights.
- Slips and falls due to steep and slippery work locations.
- Falling objects, such as debris, tree limbs and damaged utility poles.
- Electrical hazards from generators back-fed into the power grid.
- Electrical hazards from re-energized circuits.
- Falls from height.
- Fatigue from working extended shifts.
- Heat exhaustion.
Repairing downed or damaged lines is in many ways similar to installing and removing overhead lines. The difference is that in emergency conditions, there can be many unknown and changing hazards as the work progresses. Under these conditions, workers must be especially vigilant and cautious. Our crews encountered one such hazard in St. Thomas, and we feel the story is worth sharing.
The Cabrita Point Project
As part of the overall energy restoration mission for the U.S. Virgin Islands, the Cabrita Point project was discussed between the Virgin Islands Water and Power Authority (VI-WAPA) and WAPA personnel before work began. During this discussion, both groups identified what poles and sections of wire needed to be replaced for the project. At that time, VI-WAPA verbally informed WAPA that all power lines on the peninsula were de-energized. Two points of clearance were established on the line. The first was a set of solid-blade disconnects opened from an underground riser coming from nearby St. John, and the second was a set of open-removed jumpers on the opposite end of the line.
Two crews were assigned to the Cabrita Point project. Both crews’ foremen drove the entire length of the line and discussed the storm damage work that Crew One had performed earlier that week. During the conversation, both foremen discussed a good starting point, points of clearance, and locations on the line that had been tested for voltage and where personal protective grounds had already been placed.
Following this line review, Crew Two started work at a riser pole where personal protective grounds had been hung by stapling the ground wire to a pole that had been damaged by the storm. At this point, one of the project linemen commented that the underground riser was not grounded with personal protective grounds. Because of this, Crew Two’s linemen treated the riser as energized. The crew members completed their work by re-dead-ending a neutral conductor that had separated from the dead-end shoe on the riser pole.
After this procedure, Crew Two’s foreman received a phone call from a VI-WAPA representative telling him that the underground cable was energized to the bottom of the disconnect blades on the riser pole feeding back from a substation on St. John. Crew Two was immediately ordered to stop work by the foreman, who also contacted Crew One and the on-site safety manager, notifying them of the stop-work order. Crew Two then took a reading of the underground line using a digital voltage indicator that showed it was energized at 9 kV to the bottom of the switch blades.
Three days earlier, while placing personal protective grounds and testing for voltage, Crew One performed voltage testing on the underground cable, which was not between the clearance points. This was completed using an analog voltage indicator that read voltage in kilovolts. The analog indicator differs from a digital indicator – which provides a direct reading – in that the analog indicator requires voltage calculations by the user. While testing the underground cable, the crew misapplied the multiplier and concluded 20 volts on the underground line. There was discussion about the possibility of the underground line being energized overnight with neither of the two crews being notified. This possibility was not confirmed.
If It’s Not Grounded, It’s Not Dead
In this incident, personal safety was the outcome because Crew Two applied the correct safety rules to manage and mitigate a workplace hazard. During the tailgate meeting prior to starting work, they discussed what was to be done, how it was to be done, in what sequence, by whom, possible hazards and how those hazards would be addressed. Most importantly, the Crew Two linemen recognized the underground riser was not grounded once work began and treated the riser as energized, adhering to the adage that “if it’s not grounded, it’s not dead.”
After the work was safely completed, Crew One and Crew Two linemen participated in a lessons-learned discussion at the worksite. The discussion focused on what work methods were performed correctly and what work methods could be improved. Near misses, when talked about and shared, help educate others for the purpose of preventing future occurrences. Safety truly is a team effort.
About the Authors: Kevin Ripplinger is a safety and occupational health manager for Western Area Power Administration, a power marketing agency within the U.S. Department of Energy. He has more than 30 years of experience working in the electric distribution and transmission field.
Will Schnyer, CUSP, is a power system construction and maintenance adviser for the Rocky Mountain Region of Western Area Power Administration. He is a Certified Utility Safety Professional who has more than 33 years of experience working in the electric distribution and transmission field.