Doubling Up

Masterplan documents prepared for Brisbane Airport since 1983 have provided for the construction of a parallel runway to cater for traffic growth. Forecasts predicted that passenger numbers would grow from around 21 million in 2012 to reach 25 million in 2014/15. Long-term projections indicate that Brisbane Airport will serve around 50 million passengers annually by 2035, and that a parallel runway would be required sometime in the 2015 to 2020 period.

BAC commenced an environmental impact statement and a major development plan (EIS/ MDP) for the new parallel runway – NPR – in 2005, with the selected site to the west of the existing runway and terminal complexes.

The EIS/MDP culminated in a 3,000 page report incorporating the input from 30 consultant teams. Following public comment the document was lodged with the Australian government for assessment in April 2007. Later that year BAC received government approval to proceed with the NPR.

The ground to be used for the NPR is extremely soft. It has the consistency of toothpaste.

Site specific

“The new parallel is to be located in an area that was formerly part of the Brisbane River delta,” Karyn Rains, BAC’s approvals and communications manager explains of some of the challenges of the proposed site.

“Over the years the mouth of the Brisbane River has shifted over this site. This means that the ground to be used for the NPR is extremely soft. It has the consistency of toothpaste down to 30m below ground level. ” The project footprint is 360 hectares in area (3,600m long and 1,000m wide) with the runway dimensions to be 3,300m long by 60m wide. This area currently sits at around sea level. To flood proof the area up to a one in 100 year storm event and protect against climate change the ground level had to be raised by 3m.

A heavy load of sand is needed to provide a stable foundation for the construction of the runway and taxiway infrastructure on this very soft ground. The heavy sand load forces moisture out of the soilcausing the ground level to sink as the earth is consolidated in a process known as ‘settlement’. Parts of the site will sink by more than 2m.

Geotechnical analysis concluded that sand would need to be placed up to 8m on top of the softest soils to achieve a uniform settlement along the 3. 6km length. In order to raise the ground surface level by 3m, and achieve the necessary settlement, 13 million cubic metres of sand is required to be placed on the site. The necessary soil compaction will require a settlement period of up to four years for the softest areas.

BAC is regularly questioned about the reasons for an eight year construction period for the NPR, when other runway development projects have required a much shorter duration. It is that need to apply sand to the site to increase soil density, including a settlement period of around four years, that largely accounts for this timeframe.

To accelerate the settlement process, vertical ‘wick drains’ are inserted into the ground at the softest parts of the site up to a depth of 35m. Wick drains draw moisture from the soil more quickly than the action of gravity alone from the heavy weight of the sand platforms. The reclamation design involves having more than 8,000km of wick drains being spaced as close as 1m over the softest areas.

“We were faced with three significant problems,” Paul Coughlan, project director of the NPR says.

“The first was how to acquire sufficient volumes of sand at a reasonable cost? How could we get the sand to the site and distributed over the area to undertake the settlement process? How would we manage the problem of water releasing acidic content from soil over such a large area during the settlement process?” Coughlan continues: “The Queensland government undertook a major study into sand extraction prior to 2005 as part of analysis into the expansion of the Port of Brisbane. This study also considered where sand could be sourced for a new runway at Brisbane Airport. The report identified the MiddleBanks area of Moreton Bay as being an ideal source of sand. Middle Banks has sand of ideal quality for the settlement process. While the sand is of a fine grain it does not generate a dredging plume like that from silt or mud. ” Middle Banks is located near Tangalooma, adjacent to the main shipping channel.

Tidal movements readily replenish sand extracted from this area.

Importantly, Middle Banks is 12km from the nearest seagrass areas inhabited by turtles, dugongs, whales and dolphins. Middle Banks has been used to source sand for other development projects, including the original development of Brisbane Airport. The Queensland government study, testing undertaken for the EIS, and trial dredging all showed that sand extraction would have a negligible impact on Moreton Bay.

After resolving the source of sand, a decision was needed about the mooring location of the dredging vessel from which sand would be pumped along pipes onto the NPR site. This decision was influenced by the need to avoid the tidal flats of Moreton Bay, which extend around 10km off the shoreline.

“A major issue was the distance needed to pump sand through pipes between the vessel and NPR site,” Coughlan says.

“To avoid the tidal flats we had to look for a mooring site in the Brisbane River. Other shipping traffic meant we could not moor the dredge in the main channel. One of our project team identified a potential mooring site to the side of the port’s swing basin. This area is used to manoeuvre ships into and out ofdocks at the Port of Brisbane. ” Coughlan explains that: “The mooring site in the swing basin still required sand to be piped over a sewerage treatment farm, in between the runway 19 approach lights and beneath the crossing 14/32 runway.

In order to pump sand over this 4. 5km distance a slurry comprising water and sand is required. The ratio of 5:1 water to sand required a volume of water equivalent to the daily residential usage of south-east Queensland. ” Environmental management of the NPR site has become a major priority for the project. To avoid increased turbidity pollution of the waters around the NPR site, a reclamation bund was constructed around the perimeter of the construction area.

The bund contains water pumped onto the site as part of the sand slurry. Tailwater ponds within the bund enable sediment to settle to the bottom before sediment free water is released into the external waterway system. Water is not discharged into the external waterway without minimum quality standards being achieved.

The proposed NPR site includes habitat for an endangered bird species.

“During preparation of the EIS we became aware that part of the NPR site was the habitat of the Lewin’s Rail, an endangered bird. The Lewin’s Rail is extinct in Western Australia and is threatened along the east coast of Australia. They live in low density grassland areas,” Karyn Rains explains.

“In response, BAC set aside 285 hectares of airport land as a biodiversity zone for conservation purposes, 50 hectares of which is for existing or converted Lewin’s Rail habitat. All other wildlife from both on the land and in the waterways of the proposed NPR site was captured before construction commenced and relocated. ” Every speck of topsoil material and cleared vegetation has been mulched, blended and stored in stockpiles to break down into a nutrient rich reusable topsoil product to be used to landscape the area once construction has been completed.

Doubling capacity

In allowing parallel operations to take place the new runway will effectively double the airport’s traffic movement capacity and reduce overall noise impacts.

Three modes of operation have developed depending on weather conditions and the number of aircraft presenting for arrival or departure over a certain period.

The first mode, termed “Over the Bay” operations, involves aircraft arriving and departing over Moreton Bay. It enables an aircraft to land on the new runway at the same time as another is departing in the opposite direction on the existing runway. These simultaneous operations require a dry runway, not more than 5kt downwind and an arrival rate of not more than 25 aircraft per hour.

(This arrival rate is still subject to final determination by CASA and Airservices). On occasions when the downwind exceeds 5kt, but is not greater than 10kt, an aircraft can depart over the bay once the arriving aircraft has completed its approach. A dry runway is still required and an arrival rate of not more than 10 aircraft per hour.

The second mode involves runway 19 parallel operations, while the third mode involves runway 01 parallel operations. For these two modes aircraft arriving or departing from

The airlines needed to believe the value proposition of the NPR. JULIEANNE ALROE

to locations to the north and west will use the new runway. Arrivals and departures from/to the south and east will use the existing runway.

Modes two and three – which will be the predominant operations during the day and evening hours, ie 6am through 10pm – provide for the greatest traffic movement capacity, allowing the doubling of the present maximum capacity of Brisbane’s single runway of 54 per hour.

Over the Bay operations are intended to operate when traffic demand lessens and weather conditions permit. Where possible these operations will take place during noise sensitive times such as overnight or during weekends, as Over the Bay operations will reduce the impact of aircraft noise over the Brisbane area.

BAC has undertaken noise modelling for operations incorporating the NPR based on the N70 standard. N70 is used to present contours around the airport within which a stated number of flights (eg, 5, 10, 15 etc) generate noise of 70 decibels or more over a specified period of time.

Due to public concern about aircraft noise, the federal Department of Infrastructure and Regional Development undertook a study in 2013 exploring the necessity to impose a curfew on overnight aircraft operations.

A significant factor in these deliberations was the reduction in the noise footprint resulting from Over the Bay operations enabled by the NPR. As a result, the Department concluded that an aircraft curfew was not required.

Under construction

Construction of the new runway commenced in September 2012 and involves three phases: Site preparation (2012-2013); dredging and reclamation works (2013-2018);and construction of pavements and airfield (2017-2020).

Site preparation works were contracted to BMD and completed in February 2014. These preparation works included site clearing of 365 hectares; a road network for construction works; installing drainage systems; and closing the cross runway.

The contract for the dredging and reclamation works was awarded to Jan De Nuln – one of the world’s largest dredging contractors with a resume that includes the Palm Islands development in Dubai – in October 2013.

A trailer suction hopper dredge (TSHD), the Charles Darwin, was used to extract sand from the seabed of Moreton Bay and pump the slurry onto the NPR site. The dredge used powerful suction tubes equipped with a drag head, lowered from its sides to draw sand material from the seabed into a hopper within the hull. The capacity of the hopper is 30,500 cubic metres.

The process involved the dredge travelling from its mooring in the swing basin of the Brisbane River to gather sand from the Middle Banks area. Around two hours was required for the journey to Middle Banks with two-three hours needed to fill the hopper. Once back at its mooring the dredge required a further twothree hours to attach piping and pump the sand slurry to the NPR site. Each cycle took around 10 hours to complete, with the dredge working on a 24/7 basis.

Dredging and reclamation works have exceeded BAC’s expectations.

The pumping capacity and production levels achieved by the dredge was greater than forecast enabling a thicker slurry to be pumped along the pipeline to the NPR site. This resulted in significantly reduced water volumes being needed to support the pumping process. BAC have sought to operate a ‘one project, one team’ philosophy with contractors. This philosophy has achieved significant benefits during the dredging and reclamation works.

“BAC and Jan De Nul approached the dredging and reclamation works as one team focused on achieving the desired outcome,” Paul Coughlan says.

“An example of this cooperation was in gaining approval for a larger mooring system in the swing basin to secure the dredge while undertaking pumping. Gaining these approvals was the contractual responsibility of Jan De Nul. BAC, however, had previous experience in gaining maritime approvals from the Queensland government and assumed this responsibility. This reduced the approval lead time and enabled the dredge to enter operation sooner. ” Coughlan adds: “Sand pumping was completed on December 7, just six months after pumping began.

This completion date is seven weeks ahead of schedule and below budget.

Works have been completed without an operational impact to the Port of Brisbane and maintaining a high environmental threshold. ” Jan De Nul is also responsible for the movement of sand around the NPR site for the settlement process.

These earthworks are planned to be completed in mid-2015.

An announcement of the successful contractor to undertake the design of airside infrastructure will be made on January 5 2015.

The NPR is almost certainly the largest infrastructure project undertaken by one of Australia’s privatised capital city airports.

A capital cost of around $1. 3 billion has presented significant commercial challenges for BAC.

Julieanne Alroe, BAC’s CEO and managing director explains: “When the capital city airports were privatised in 1997 all had excess operational capacity.

Subsequent infrastructure investment typically involved increasing the size or upgrading terminal facilities. Only incremental additions to runway, taxiway or aprons were needed. It was relatively straightforward to fund these projects. ” “The NPR is a step change project and raised a number of commercial concerns. Would the privatised airport ownership model be able to undertake the investment required for large infrastructure projects? Could we keep the support of our financial investors and directors, plus retain our credit rating? To allay concerns from our owners and investors we prepared a well-defined operational imperative to capture the need for the NPR.

We were able to get everyone to support the NPR being the right long-term solution to meet our future traffic needs,” Alroe added.

To increase corporate equity to enable the required level of commercial borrowing without weakening the balance sheet, BAC shareholders did not take dividends from the company for a number of years. Dividends are now being paid.

BAC encountered resistance from airlines to increasing airport charges while the NPR was still under construction. Airlines wanted to pay for the new runway only after it entered operation.

A negotiated settlement has now been reached whereby BAC will fund 75 per cent of the cost of the new runway through commercial borrowing and contributions from shareholders. The remaining 25 per cent will be funded by airlines through landing fees.

Airport charges will increase gradually over the next five years, to a maximum of $3. 15 for each international passenger.

Alroe explains how agreement was achieved with airlines: “Earlydiscussions with airlines about increasing airport charges had become adversarial. They are challenged with cost pressures and did not want to pre-fund the development. The airlines needed to believe that the value proposition of the NPR would support an increase to airport charges. Our discussion had to change from only about cost to being around value. To do this we sought to provide opportunities where BAC could assume some operational responsibilities to reduce service costs to airlines through economies of scale. Theseopportunities include: transporting passengers between the domestic and international terminals; waste removal and cleaning; and implementing self-service check-in facilities. ” The EIS included an ongoing requirement for BAC to undertake a long-term community consultation process. Noise impact has been a key element of the consultation process undertaken with the local community. BAC has established an interactive display in Skygate, a shopping centre within the airport precinct where people can determine the impact of aircraft noise over their property. This initiative is also available online at bne. com. au. It enables residents to make an informed decision before deciding to invest in an area.

The NPR is the largest infrastructure investment project that has been undertaken by a capital city airport since they were privatised in 1997. It has presented environmental, technical and commercial challenges. Despite these hurdles the project is progressing ahead of schedule.