'We would mix our own explosive, add some dynamite and set it off with a safety fuse. When we were ready, we would light the fuses and hide under the bulldozers. When the charges fired, there would be rocks, stumps and dirt raining down everywhere.'

The fact that nobody ever got hurt was more a matter of luck than good management, he said.

The days of using dynamite are long gone. 'We don't use dynamite any more, and we don't use safety fuses. Modern explosives are safer than the older stuff, provided they are used correctly by trained and experienced personnel. We must always remember that explosives are designed to explode. No explosive is completely safe. If it were, it wouldn't work.'

The blasting industry has changed so much that there are more safety standards, laws and regulations than you can shake a stick at. Things are so safe, in fact, that the only injury Mr Butchart can recall in almost four decades in the industry was about 20 years ago, in a quarry, when a member of a blast crew was bitten by a snake. But there have been some near misses.

'Many years ago we were working a small quarry in a farmer's paddock. We lit a three-minute fuse and drove to a safe distance. To our horror, a mob of sheep wandered over the blasting site. There is no safe way to stop a fuse, so we just watched.'

Mr Butchart said he learnt three things that day.

'One: sheep are like cats - they do cartwheels, but they all landed on their feet. Amazingly, there were no fatalities. Two: circumstances can change dramatically in three minutes. Electric firing is instant and is much safer (that was the last time I ever used a safety fuse - I refuse to use it these days, I don't like losing control for three minutes). And three: the farmer told us he had closed the gates, but he forgot one. Now, I always check personally. I never rely on what someone else tells me where safety is concerned.'

In another close shave, he and his crew were into a 10-second countdown, firing electrically, when his siren man spotted two teenagers on trail bikes, illegally riding down the hill directly towards the blast area.

'The siren man turned off the siren,' Mr Butchart said. 'This was unusual, so with three seconds to go, I switched off the firing machine. Then I found out what had happened. If I had continued with the countdown, two boys would have been launched into orbit.

'From this we learnt that fences, blasting signs and sirens are a deterrent for sensible adults, but simply arouse the curiosity of children. No-entry signs require human sentries to enforce them.'

Mr Butchart came to Hong Kong in 1994 at the request of a Japanese contractor who needed to blast next to the Kap Shui Mun Bridge, which connects Ma Wan and Lantau. 'There were a few challenges to ensure the blasting would not damage the bridge,' he recalled. 'Later we carried out blasting near what is now the Disneyland interchange, and did some foundation blasting for the Ting Kau Bridge.'

Hong Kong presents some of the most technically difficult blasting in the world, because you are never far away from people and valuable property. 'But it is also very rewarding as it usually makes you part of a landmark project, such as bridges, expressways and rail extensions,' Mr Butchart said.

His work has helped shape Hong Kong into much of what it is today.

'I enjoy being an essential part of the construction industry, building tomorrow's Hong Kong. Without explosives, Hong Kong as we know it could not exist,' he said.

Before Hong Kong, he was involved in some interesting developments in Australia. 'One project required deepening the spillway of a dam. The blasting wasn't difficult, but the potential consequences were severe. If the dam had breached it would have flooded 10 per cent of Sydney.'

He has also helped to construct ski slopes in Alpine ski resorts.

'Apart from the climate and the steep working conditions, the most important aspect was to protect the aerial ropeways from any damage. After all, there is no point improving a ski slope if you destroy the chairlift which provides access to the slope.'

According to Mr Butchart, there is no one-size-fits-all formula for blasting safety, and all projects have degrees of difficulty. Blasting in gold mines, for instance, must be done carefully to avoid dispersing the gold-bearing rock and losing it. Blasting in diamond mines requires care and skill for obvious reasons. And in coal mines, there is always the risk of causing fire or coal dust explosions.

As a rule, however, blasting engineers should never underestimate the power of the materials they are working with.

'A typical site formation blast might require 5,000kg of explosives to break 40,000 tonnes of rock. This quantity of explosives will release about 15,000 megajoules of energy. A megajoule is the amount of energy required to run a light bulb for about six hours. So we are talking about 15,000 times as much energy, released in less than a second.'

Blasting in high-density places such as Hong Kong inevitably affects the public, and it is a blasting engineer's job to minimise the effects.

'The public can be affected in many ways. Excessive vibrations in the ground can cause damage to structures. Blasting may destabilise surrounding slopes. A dust cloud can reduce visibility. A sudden noise may startle people. And flying rocks must be avoided. All of these aspects are taken into account by the blasting engineer during the design phase of a project.'

After decades of handling different explosives in the business, Mr Butchart finds illegal fireworks by far the most dangerous. 'There is no quality control and they are designed to be ignited by a spark. A bunch of fireworks packed in a box contains quite a large quantity of explosive material. One spark or cigarette end and you could be guest of honour at a barbecue,' he said.

Unexploded bombs are also more dangerous than the commercial explosives used today. These are still found occasionally on construction sites more than 60 years after the war ended. 'If people find bombs or fireworks, they should ring the police and de-camp to a safe place, rapidly. To be safe, they should be about two MTR stops away. Explosives incidents are not spectator sports. It is more fun to read about it the next day, knowing you still have two eyes, two ears and 10 fingers.'

So with a diploma and a degree in forestry, how did he get into the business of blowing things up?

'I was a bit of a pyromaniac as a child,' he said. 'But when I got into the construction industry I found that a lot of blasting was required. Naturally I wanted to find out all about it.'

In those days, training was on the job. 'Nowadays, most countries require a formal training course as well,' Mr Butchart said. 'There is no formal training course in Hong Kong yet, but I expect this will change before too long.

'The key to safety is good training, good supervision and attention to detail. Most accidents occur with experienced shotfirers in charge who have fallen victim to complacency. Every situation has to be properly assessed. There are no prizes for having a guess when you are dealing with energetic materials.

'Every blasting job is different, but no blasting task is easy. If you walk on to a job thinking it is going to be easy, you are cruising for a bruising.'

Unlike other careers, where it is accepted that people learn from their mistakes, in the blasting industry there is zero room for error. 'When you are dealing with energetic materials, your first mistake can take you out in a blaze of glory,' Mr Butchart said.

And if you think there are public rewards for this profession, think again.

'Blasting engineers traditionally keep a low profile,' he said. 'For reasons of safety and security, people in the industry tend to avoid publicity. It is an industry for quiet achievers. Publicity-seekers should seek alternative employment,' he said.

And what have been the highlights of his career?

'The highlight for me is that I have undertaken well over 5,000 blasting events without ever creating newspaper headlines.'

EXPLOSIVE DATA

Explosives used in Hong Kong: 2,000 tonnes a year

Explosives use worldwide: 8 million tonnes a year

Rock broken with explosives: 50 billion tonnes a year

Energy released by explosives: 25 terajoules (25 trillion joules a year)