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Implosion of Radio Network House

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Radio Network House was imploded on 5 August 2012

The implosion of Radio Network House on 5 August 2012 was New Zealand's first ever controlled building demolition by explosives. Like most other buildings in the Christchurch Central City, Radio Network House was damaged beyond repair in the 22 February 2011 Christchurch earthquake. The right to push the button for the implosion was put up for auction on the TradeMe website, and became the auction with the third highest page views ever. The winning bid of NZ$26,000 was made by a consortium of demolition contractors, who allowed the Child Cancer Foundation to nominate a six-year-old boy from Queenstown to trigger the event. The implosion went without any problems and it is anticipated that this will have paved the way for many more implosions in New Zealand in general, and in Christchurch in particular.

Background

Radio Network House in June 2012, displaying the Newstalk ZB logo

The office building was constructed in 1986.[1] The 14-storey office tower was located at 155 Worcester Street, on the north side of the street and in the block between Manchester Street and Latimer Square.[2] In the 1990s, Telstra New Zealand had the naming rights to the building, prominently displaying the Clear logo. The naming rights changed to The Radio Network, with the building called the Radio Network House. The office tower last displayed the logo of Newstalk ZB, which is part of The Radio Network.[3] The building was owned for its last twelve years by Greg Hedges through his company Nor West Arch No.4 Ltd.[4]

Canterbury was hit by a series of earthquakes, and the 22 February 2011 Christchurch earthquake damaged the office building beyond repair.[2] About 400 people worked in the building before the earthquakes.[5]

Auction

Soon after the announcement was made that the implosion had been approved, it was reported that the demolition contractors considered the right to push the button for the implosion up for auction, with the proceeds going to charity. "I've seen them go for $6,000" is how one of the company representatives was quoted, but the issue of liability needed to be worked through.[6] The auction was set up on TradeMe and went live on Tuesday, 24 July, at 11 am. It was set up with a $1 reserve (meaning that theoretically, the right to push the button could have gone for just $1).[7] The auction was hugely popular and within one hour, bidding had reached $6,000.[8] Bidding reached $30,000, but some bids were considered illegitimate and TradeMe staff removed them. In other cases, bidders themselves requested to be removed, for example where a flatmate had used a person's laptop and put in a bid as a joke.[9]

When the auction closed, it had received the third highest number of viewers ever, at 459,420 views.[9][10] The winning bid was $26,000, placed by a consortium of seven demolition contractors who currently undertake demolitions in the Christchurch Central City (D Construction, Dormer Construction, Jurgens Demolition, March Construction, Pro Tranz Contracting and Clampet Developments, Shilton and Brown Demolition, and Ward's Demolition). They gave the right to choose a person to push the button to the Child Cancer Foundation, who nominated a six-year-old boy from from Queenstown.[10]

Proceeds from the auction have gone to the restoration of the Isaac Theatre Royal (centre) in Christchurch

The charity chosen to receive the proceeds of the auction was the Canterbury Earthquake Heritage Buildings Fund,[8] who passed the funds to the Isaac Theatre Royal in Gloucester Street, a heritage building registered as Category I by the New Zealand Historic Places Trust.[7][11] The Government of New Zealand has pledged to match donations towards the restoration of heritage buildings dollar for dollar, so the final amount received by the Isaac Theatre Royal was NZ$52,000.[8][10][12]

Implosion

On 30 August 2011, Canterbury Earthquake Recovery Authority (CERA) added Radio Network House to the list of buildings to be demolished.[13] On 17 July 2012, The Press reported that implosion of Radio Network House had been approved by CERA.[2] The same day, a press conference was held, where representatives of the demolition companies involved and of CERA addressed the media.[14] The main contractor for the demolition was Naylor Love, who engaged Ceres New Zealand for the implosion. Ceres in turn partnered with Controlled Demolition, Inc., which has a track record of 9,000 implosions and is considered a world leader in the field. It was considered that the implosion of Radio Network House was a test case, as the technique had not been applied in New Zealand before, and there are still many more tall buildings to be demolished in Christchurch.[6][15] The implosion was challenging for Controlled Demolition, Inc., as New Zealand buildings are designed to withstand earthquake loading and have thus much more reinforcing in them than the buildings they usually deal with.[1]

Before demolition, buildings are stripped of their contents, including internal gib linings. As the fees for dumping demolition waste have risen since the earthquakes, it is more economical for demolition contractors to produce 'clean' demolition material.[16][17] Holes were drilled into support columns of the building and filled with a total of some 60 kg of explosives, which when set off, would destroy the support structure and cause the collapse of the building.[15] A challenge for the demolition contractor was that explosives available in New Zealand are low-velocity and low-energy.[1]

A representative from Ceres stated that the implosion would shorten the demolition process by some six weeks and would save money. Costs were around NZ$1m for the implosion, compared to some NZ$1.2m for a conventional demolition, with the owner's building insurance covering the costs.[2] The building's owner, however, stated that the implosion was not a cheaper option for his company than a conventional demolition, but it "would save others thousands". He likened the consent process to Christopher Columbus wanting to sail to America, with everybody telling him that it can't be done.[4]

The owner of the Westende building, on the corner of Manchester and Worcester Street and some 80 metres (260 ft) away from Radio Network House, threatened to seek a court injunction against the implosion. He raised concerns about potential seismic activity, possible damage to his new building, and noxious contaminants transferred by dust.[18] The original Westende building had been destroyed in the first earthquake in 2010 and was one of the very few new buildings in the centre of Christchurch to have been rebuilt already.[19] The concerns were dismissed by the demolition contractors[20] and agreement over an acceptable process was reached between the parties without court action.[10]

The demolition companies involved appealed to the public on the day prior to the implosion to stay away for health and safety reasons, and watch the proceedings on TV or the internet.[21] Several television stations had live streams of the event, and The Press announced that they would post a video on their website shortly after the implosion. An exclusion zone was put in place, with the closest distance to Radio Network House approximately 200 metres (660 ft).[21]

Despite the appeal, thousands of onlookers filled the street on Sunday morning of 5 August.[22] Punctually at 8 am, a series of short explosions could be heard, followed by another series a couple of seconds later. The building collapsed towards the north as planned, and the implosion manager from Controlled Demolition, Inc. was quoted as saying that "it went a bit further than I had hoped so I am lucky".[23] The explosions were heard around Christchurch.[24]

One of CERA's objectives in approving the implosion was to find out how the soil behaved, as Radio Network House was built on one of the worst soils in Christchurch. Seismograph readings showed ground velocity of 12 mm/s, which is apparently comparable to a large truck slowly driving across the demolition site. With any residual concerns about the performance of poor soils during building implosions removed, it will be much easier for other building owners to obtain consent from CERA.[22] Further implosions are likely, with a representative from from Controlled Demolition, Inc. describing the Christchurch market as a "target-rich environment".[22]

The implosion attracted global attention, with media in the Australia, Canada, Ireland, South Africa and the United States covering the event.[5]

References

  1. ^ a b c Post, Nadine M. (6 August 2012). "Quake-Damaged Building Implosion One for the Books". Engineering News-Record. Retrieved 27 August 2012.
  2. ^ a b c d Turner, Anna (17 July 2012). "Newstalk ZB's Radio Network House To Be Imploded". The Press. Christchurch. p. A7. Retrieved 6 August 2012.
  3. ^ "The Radio Network". The Radio Network. Retrieved 7 August 2012.
  4. ^ a b "Building blast a bittersweet moment". The Press. Christchurch. 6 August 2012. p. A1. Retrieved 6 August 2012.
  5. ^ a b "Implosion grabs attention abroad". The Press. Christchurch. 7 August 2012. p. A8. {{cite news}}: |access-date= requires |url= (help)
  6. ^ a b King, Caroline (18 July 2012). "Implosion Could Be Test Case For Christchurch". The Press. Christchurch. p. A10. Retrieved 6 August 2012.
  7. ^ a b Turner, Anna (25 July 2012). "Auction to push detonation button exceeds $15K". The Press. Christchurch. p. A2. Retrieved 6 August 2012.
  8. ^ a b c Turner, Anna (1 August 2012). "Bidding stalls on implosion auction". The Press. Christchurch. p. A5. Retrieved 6 August 2012.
  9. ^ a b "Illegitimate bids removed from demolition auction". Newstalk ZB. 1 August 2012. Retrieved 7 August 2012.
  10. ^ a b c d Mathewson, Nicole (3 August 2012). "Boy to push button for implosion". The Press. Christchurch. p. A3. Retrieved 6 August 2012.
  11. ^ "Theatre Royal". New Zealand Heritage List/Rārangi Kōrero. Heritage New Zealand. Retrieved 12 July 2012.
  12. ^ "Six-year-old boy helped the ITR by blowing up a building!". Isaac Theatre Royal. Retrieved 8 August 2012.
  13. ^ "Radio Network House". Canterbury Earthquake Recovery Authority. Retrieved 8 August 2012.
  14. ^ "Radio Network Building implosion press conference". Canterbury Earthquake Recovery Authority. Retrieved 8 August 2012.
  15. ^ a b "Radio Network House - Building Implosion - Sunday 5 August 2012". Canterbury Earthquake Recovery Authority. Retrieved 27 August 2012.
  16. ^ Williams, David (8 September 2011). "Rubble 'difficult, risky venture'". stuff.co.nz. Retrieved 27 August 2012.
  17. ^ "The Press is shown inside Radio Network House as it is prepared for implosion on August 5". The Press. 2012. Retrieved 27 August 2012. {{cite news}}: Unknown parameter |month= ignored (help)
  18. ^ Young, Rachel (26 July 2012). "Injunction could stop implosion". The Press. Christchurch. p. A3. Retrieved 6 August 2012.
  19. ^ Heather, Ben (28 January 2012). "Vote of faith in central city area". The Press. Christchurch. Retrieved 8 August 2012.
  20. ^ "Concerns over implosion unfounded - Manager". Newstalk ZB. 26 July 2012. Retrieved 8 August 2012.
  21. ^ a b "Cantabrians Urged To Stay Home During Implosion". The Press. Christchurch. 4 August 2012. p. A7. Retrieved 6 August 2012.
  22. ^ a b c "Perfect fall sets scene for more". The Press. Christchurch. 6 August 2012. p. A1. {{cite news}}: |access-date= requires |url= (help)
  23. ^ "Radio Network House imploded". The Press. 5 August 2012. Retrieved 6 August 2012.
  24. ^ "Radio Network House". The Press. Christchurch. 6 August 2012. p. A6. {{cite news}}: |access-date= requires |url= (help)
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