In a contract with the Ministry of Defence, Fulton Hogan and two other contractors are involved in ripping up an old taxiway, recycling the concrete for a new taxiway and constructing an aircraft hard stand apron at RNZAF Ohakea. Richard Silcock explains.
The Royal New Zealand Air Force has new jet-powered Boeing P8A Poseidon search and maritime surveillance aircraft arriving to replace its aging turboprop Lockheed P3K Orions. It is also transferring number 5 Squadron RNZAF from Whenuapai to Ohakea.
In preparation, the Ministry of Defence contracted Fulton Hogan, as lead contractor, to rip up and replace an aging 650 metre-long taxiway at Ohakea and construct a new aircraft hard stand apron.
Also included in the contract is the construction and installation of various utility services that include drainage, lighting, water supply and an aircraft washing facility.
Locally-based Mills Albert Contractors is providing the required earthworks and Central Demolition is sub-contracted to rip up the old tarmac and crush and recycle the concrete for use as basecourse for the new taxiway.
Under a separate contract Hawkins Construction has been appointed for the construction of a purpose built new hangar to accommodate and service the new aircraft.
The hexagonal concrete slab tarmac of the old taxiway is believed to date back to WW2 with the concrete now showing signs of deterioration and breaking up, making it unusable and unsafe for aircraft.
Demolition work began in October last year and required the 285mm thick hexagonal concrete slabs to be first pockmarked using an excavator equipped with a pneumatic breaker to fracture the concrete over an area of 9850 square metres.
Ian Butcher, operations manager for Palmerston North based Central Demolition, says this allowed them to fracture the concrete and then rip it up using an excavator into pieces suitable for ‘feeding’ the crushing machine.
“We brought our Keestrack B4 mobile jaw crusher onsite to speed up this process,” says Ian. “This alleviates the need to cart the old concrete to an offsite crushing plant, thus saving both time and trucking expense.
“We were achieving 120 tonnes per hour throughput on average, crushing the concrete to GAP65mm, which has been recycled for use in the new taxiway basecourse layer.
“Our involvement with this part of the project is pretty much completed now. It took five months with our team working a normal Monday to Friday week.”
Fulton Hogan’s on-site project manager, Reuben Saathof, says that with the good weather over the past summer months they made good progress with both the demolition work and the earthworks.
“Eighty percent of the earthworks for the taxiway have now been completed and we expect to have this fully completed prior to winter,” says Reuben.
“We are now installing drainage, concrete stormwater culverts and PVC ducting for lighting cables and other services, including the installation of new fire station pumps and storage tanks.
“Some 900 metre x 1050mm in diameter concrete stormwater culverts have been laid along with 3000 metres of network drainage pipes. This includes special slot drains for stormwater collection and drainage for the apron and taxiway. Around 10 kilometres of ducting has been required.
“Once this work is complete we will commence laying the basecourse aggregate in preparation for concrete and asphalt paving which will be batched out of mobile asphalting plants nearby.
“The taxiway will be 650 metres long and 23 metres wide and paved with 100mm thick AC20. The hard stand apron is being constructed using pavement quality concrete (PQC) at 385mm thick.”
While the works are using traditional tarmac pavement construction materials and techniques, Reuben says that the fact of carrying out extensive civil works on an operational ‘live’ military airfield has brought with it some extra challenges.
“The air force base at Ohakea is a high security area so all our 80-100 staff working on the project undergo a security clearance procedure and as we are working in a fenced-off area of the airfield itself there is strict security and control of all staff and vehicles coming and going.
“We have established a good working relationship with the air force project team on the base and we have regular meetings with them to discuss and plan works around the base’s operational requirements.
“The five hectare construction site where we are working has required careful environmental monitoring and extensive ground testing for any contamination and we are also regularly testing any surface water for any contaminants.
“The logistics of working in a semi-remote area has also brought with it some particular resourcing challenges,” says Reuben. “In addition to the local contractors and our local team from Palmerston North we have brought in extra people from our branches around the country.”
Subject to the weather and any Covid-19 lockdowns, the replacement of the taxiway and hardstand apron at RNZAF Ohakea is due to be completed by June next year.
This article was first published in the April 2021 issue of Contractor Magazine.