Storm of the Century? On the face of it, the region appeared ill-prepared for the devastation brought about by the ice storm. But is it possible to be prepared for an event that is as uncommon as it is severe? Engineers typically design structures and procedures based on worst-case scenarios that are likely to occur no more than once a century. This storm, classified by Environment Canada as "the worst ever to hit Canada in recent memory" was beyond any standard or test simulation previously conducted - a storm that by some estimates fit the once-every 500-years category. "You could not build anything that could withstand the kind of conditions experienced during that storm,"said Earl Davison, an Ontario Hydro director of asset strategy. While the storm went beyond anything anticipated in the usual tests and standards, those same standards played a crucial role in mitigating the storm's effects, and in facilitating the recovery effort. A case in point is the operation performed by the Ontario Hydro team to sever ice-coated skywires that threatened to short-circuit live wires, or worse, topple entire structures. Before the job began, the six-member team identified hazards during mock trials under controlled conditions. Every aspect was tested repeatedly. Familiar equipment was adapted to fit the need: ordinary cutting tools were attached to insulated sticks long enough to reach from the helicopter to the top of the tower. Standard helicopter maintenance and operation procedures allowed the team to safely remove the back door and to communicate with team members on the ground. Said Roger Ryan, group leader of Ontario Hydro's protection and control: "All of the training programs, manuals and standards that are sometimes taken for granted gave us a formal structure that was essential." Standards ensured the interchangeability of parts - and of people. More than 1,500 utility workers, tree trimmers and other specialists from New Brunswick, Nova Scotia, Michigan, Vermont and the New England states worked alongside Ontario and Quebec crews. A 40-member Toronto crew of experts in electrical distribution systems worked on Montreal's south shore. The similarities in systems meant that the imported workers needed little or no special training. As well, the compatibility of standards meant replacement materials such as cables and poles could be obtained and installed with relative ease.
"The benefit of standards is that you know you don't have to worry about the quality of materials when it arrives," said David Horrocks, a supervising design engineer at Ontario Hydro. "Instead, you can concentrate on getting the work done."
Lessons Learned Utility companies and standards developers are now reviewing the ice storm and its effects, trying to determine what went right and what went wrong. The storm offered some valuable lessons that are likely to be applied in future standards, and in the ongoing reconstruction of the electrical distribution system. The transmission systems that make up the heart of the electric grids will likely bear the toughest scrutiny. In Quebec, transmission lines that run from James Bay, Manicouagan and Churchill Falls suffered massive damage. In the 30 years since Hydro-Quebec built the lines, not one tower has fallen. As a result of the storm, 130 giant metal towers, each worth $100,000 in materials alone, toppled like dominoes. As well, 60 lower-voltage towers and 800 wooden distribution structures collapsed, reducing power to the Montreal region by 60 per cent. Hydro-Quebec is a world leader in electrical standards. In the early 1970s, the utility increased the standard of ice resistance for its transmission lines to 45mm, up from the Canadian standard of 12mm. Transmission towers which would normally be required to endure 15mm of freezing rain were built to three times that strength. Those standards exceeded North American reliability criteria in part because of the importance of hydroelectricity in Quebec and the region's often extreme climatic conditions. So what went wrong? One factor was Quebec's transmission system, which stretches north to south across the entire province. Shortly after the storm, Hydro-Quebec announced it would spend $650 million this year for new pylons and power lines, including an emergency back-up line that will tap into Ontario's power grid to erect anti cascading pylons to prevent toppling and further strengthen the system. Utility officials in both provinces may consider other options,such as a plan to design insulators to act as mechanical fuses which would break under a specific pressure - rejected by some engineers as too dangerous because it would add to the debris - or a system of sequenced failure, in which the arms of the tower would collapse under weight instead of the entire structure.
Down the Line The power distribution network of poles, substations and wires that reduce voltages and carry power to individual homes suffered the brunt of the storm, and caused the most havoc. Overhead telephone and power lines that drop from transformers to the home must conform to the minimum CSA standard of one-half-inch (12.5mm) radial ice resistance. In many cases, these lines were the first to snap. The next weakest link was the ubiquitous hydro pole. With an expected lifespan of 35 years, a wooden hydro pole's worst enemies are usually base rot and woodpeckers. In the space of a week, ice loads in Quebec knocked down, sheared off or uprooted some 30,000 wooden utility poles, and just as many crossarms. Ontario Hydro lost 11,000 wooden poles, valued at $3,000 each, and sustained damage to 40 per cent of its distribution system. Although two out of three eastern Ontario customers were affected, Ontario Hydro officials say the overall load loss was kept to 25 per cent. Although suppliers manufacture poles on a just-in-time basis rather than stockpiling them, there were no reports of a shortage of poles. Just as important, utility procurement teams knew exactly what they were getting in advance, thanks to standards covering the poles themselves, crossarms, piles, wood preservative sand insulator pins. With speed a critical factor in the recovery, utility emergency crews did not need to think twice about the quality of the product they relied upon. The storm also revitalized an ongoing debate about the efficacy of underground distribution systems, and whether they are a cost-effective way of avoiding the kind of trouble posed by exposing electrical lines to the elements.
Dressed for success Working with high-voltage electrical equipment is always dangerous - add freezing rain, high winds and falling debris to the mix and the job can turn deadly. For that reason, the ice storm was a successful trial of everyday work items, from insulated gloves, hard hats and safety harnesses to fibreglass ladders and voltage detectors that identify live power lines. Rigorous standards produced by both Canadian and international standards development organizations cover durability, reliability and safety characteristics of the clothing and equipment used by workers. Clothing, for example, is subjected to tests to determine the degree of heat resistance in fabrics. While working on power lines, crews wear conductive suits that are 75 per cent Nomex and 25 per cent stainless steel to protect their bodies from inadvertent exposure to electrical arcs. The ice storm provided at least one trial by fire for a Canadian-made product. In the fall of 1997, Ontario Hydro asked two of its crews to try out new, fire-resistant outerwear. The clothing had been designed by company line workers for comfort and protection beyond both CSA and International Electrotechnical Commission (IEC) standards. Declared Toronto consultant Ernie Jones, chair of the IEC's Canadian subcommittee on protective clothing and tools: "They are state-of-the-art and we could not have had a better test."
Raised the bar In the months ahead, the ice storm that crippled a region will be analyzed in minute detail. No one could have predicted that as much as 100mm of freezing rain would fall for four relentless days. Nor is it possible to speculate what might have happened had the storm tracked through less populated areas. In terms of standards, the Ice Storm of '98 - whether a fluke of nature or a portent of trouble ahead - has already raised the bar.
Reprinted from Consensus, the newsletter of the Standards Council of Canada. Photos courtesy of Hydro-Quebec.