When the last of the winter snow melted around the 88 transformers stored at its operations and maintenance building in Melancthon, Canadian Hydro Developers discovered that one of the units had developed a slow leak of oil.

"It was from a little valve at the bottom of the transformer, a brass fitting," said CHD's CEO, John Keating, when asked about the leak in a phone interview last week from his Calgary office.

He said the transformers contain 1,200 litres of biodegradable mineral oil.

"Fortunately, we caught it early," he said, when it had leaked only 380 litres. He said the composition of the oil is such that there was no threat to the environment. The problem "was more visual than anything else."

The leak would have been discovered even earlier, he said, if it hadn't been going through the snow into the gravel beneath. "It was only after the snow melted that it was discovered."

The next undertaking is to remove the valves on all transformers - 45 in the field and 88 in storage - and replace them with permanent plugs.