Business profile: Yakka TDC

By: Lyndsay Whittle, Photography by: Lyndsay Whittle

Deals on Wheels spoke to Yakka TDC to find out how the Auckland-based company was carrying out the demolition of the 45m-high Paul Kelly stand in Christchurch

When a natural disaster strikes, it can be catastrophic to both human lives and the landscape surrounding them. The 2011 Christchurch earthquake claimed 185 lives, injuring many others, and levelling countless iconic buildings and structures. It was recorded as New Zealand’s fifth-worst disaster.

The 28m high reach excavator making a start

The aftermath saw people come together to rebuild their city and their lives, and their efforts continue to date. Eight years on, Christchurch is undergoing a massive rebuild where structures are being demolished before new ones are built. One such complex is Lancaster Park, which, at first, appeared to had escaped any serious damage.

Onlookers on the day of the quake reported seeing the 45-metre-high Paul Kelly stand swaying to around half a metre as the 6.3 magnitude earthquake moved the ground up, down, and sideways.

While on first sighting, the building didn’t look in too bad a shape, a closer inspection revealed cracks that went through cross-sections of 400mm-thick walls.

The damage the structure sustained had, in fact, rendered it uneconomical, perhaps impossible to repair, thus the decision to have it demolished. The slightly smaller Robbie Deans stand is about to suffer the same fate.

Getting to work

To give some idea of the scale of the demolition, it’s worth mentioning that although smaller than the Paul Kelly stand, the Robbie Deans stand still had the capacity of seating 13,000 sports fans.

Needless to say, this is a huge job that requires a lot of expertise. Enter, Auckland-based firm, Yakka TDC (the TDC stands for Transport, Demolition, and Civil).

Machine on the job

I met up with Yakka TDC’s director Bruce Levien and demolition manager Steve McSkimming on-site to try to gain some perspective of the size of the operation.

One of the first things to catch the eye is the 400-tonne crane being used to lift-off large concrete panels, most of which weigh 25 tonnes.

The high-reach machine working at full height

Bruce explains that although the crane’s jib is around 50 metres, with the fly jib adding another 30 metres to its reach, bays still had to be cut into the structure to allow the crane to reach over to building in order to facilitate the removal of the 25-tonne panels.

Rather than dismantling Yakka’s own 250-tonne crawler crane in Auckland, shipping it to Christchurch, reassembling it for use on the site, and then having to carry out a reversal of the procedure in a year’s time when the demolition is completed, Bruce says that he and his team made the call to hire-in the Christchurch-based 400-tonne machine.

Demolition manager Steve McSkimming says the Yakka crane, when broken down to its component parts for transportation, would fill approximately 17 truck and trailer units, so it made sense for them to hire the local crane owned by Daniel Smith Industries.

Both Bruce and Steve say the Yakka crawler crane currently in Auckland, although smaller in lifting capacity to the hire rig in use on-site, has a longer main jib and measures in at 90 metres, with another 30-metre capability with the fly jib attached.

Work synergy

Yakka has its own dust-suppression equipment

While watching the crane in action, it’s apparent that coordination between all the parties involved in each manoeuvre is paramount. Steve gave a brief summary of how it all comes together:

"Every foreman on the site has a two-way radio, so the crane-man has a radio, the foreman in charge of the strip-out has a radio, both the dogman at the top and the dogman at the bottom have radios as well."

Perhaps most importantly, the concrete cutter has direct communication with the crane-man to tell him how much lifting weight to put on the chains. In fact, everyone on-site knows what’s going on the site all the time.

It’s apparent to anybody visiting the demolition site that a lot of patience needs to be applied during the course of a day’s work. A classic example of which is that before the upper section bleachers on the Robbie Deans stand can be craned off, 1400 holes needed to be core drilled for the fitting of the chains. It’s not only hot and dusty work but also a long and tedious task, with each hole taking roughly 20 minutes to bore.

Once the holes have been drilled, the next step is to gas-cut the steel brackets before lifting can begin. Steve says that although each section of the bleachers typically weigh-in at about 3.5 tonnes, a doddle for the 400-tonne crane, oddly enough, the component that can cause the most frustration during removal is the incredibly-strong silicon used in joining the concrete that creates suction between the two surfaces when lifted.

The remedy for this, he says, is to lift each bleacher out unevenly while being careful not to overstress the concrete or the chains being used to lift them. It usually takes around 45 minutes to remove each bleacher, however, Steve stresses that that’s only if things go to plan.

But as we all know, things don’t always go to plan, in which case, it could take upwards of an hour and a half per bleacher.

10-month deadline

Nibbling away

Given that Yakka TDC began work early in March with the intended timeframe to have the demolition completed by Christmas 2019, one may very well ask how the team plans on meeting the deadline considering the detail of attention required to removing components that weigh a mere 3.5 tonnes, when the entire job consists of some 60,000 tonnes of product.

The answer to that conundrum comes in the form of Yakka’s high-reach excavator with five tonnes of breaker attached to its 28-metre boom. The machine was already nibbling its way through some of the lower sections of the Paul Kelly stand on the day of our visit.

Yakka is contracted to remove both stands to ground level at this stage, however, Bruce says that a variance to the contract could possibly be made to include removal of the foundations when the current contract ends. "We’ll just have to wait and see," he says.

There were 15 workers on-site and almost as many machines working but because of the sheer size of the site, both man and in many cases, the machines they were operating appeared small in comparison.

Looking at the mass of reinforced concrete and all that rebar that needs to be cut and nibbled through, the question just had to be asked as to whether it wouldn’t have been quicker to use explosives.

Sensors placed around the site detect movement and vibration

Bruce said that the council had made it quite clear to all tenderers that the use of explosives was definitely not an option given the building’s proximity to the local business district, shops, houses, etc.

In fact, shock and vibration factors are monitored by sensors that are placed in strategic points around the site, the recordings of which are closely monitored by council staff.

A Yakka MAN and a Scania awaiting loads

Currently, Yakka has two truck and trailer units working out of the site taking the concrete to Rangiora where it will be processed. Bruce says they will soon increase it to five units to do the job.

He adds their Metso LT95 jaw crusher is currently on its way down from Auckland to take care of that part of the process.

Some mind-boggling figures to ponder:

  • Boring those 1400 holes could become a really boring business, as it takes about 20 minutes to bore just one hole. That’s three holes per hour or 36 for a 12-hour shift.
  • The high-reach 50-tonne digger brings down 102 tonnes per day and has to date taken down 4382 tonnes mass
  • There is an estimated 4000 tonnes of steel rebar in the two stands. That’s just over half the steel used to construct the Eifel Tower.
  • The 470 high-reach brings down 142 tonnes per day, equalling 6116 tonnes mass
  • The two smaller 225 machines do 211 tonnes per day, or 9060 tonnes mass, giving a total of roughly 10,000 tonnes mass already taken from the Paul Kelly stand, leaving approximately 20,000 tonnes mass to go.

Note: Figures given as at mid-June 2019

It doesn’t look like the work’s going to run out anytime soon, as there’s the Robbie Deans stand to go for good measure.

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