Board Meeting: September 2014
Agenda Number: 12 (ix)
File Ref: AI0037
LORD HOWE ISLAND BOARD
Business Paper
ITEM
Runway Resurfacing and Drainage Improvements
BACKGROUND
The resurfacing and drainage improvements of the airport runway are planned to occur in
May - July 2015, with a budget of $8 million available.
In late 2012 a capital bid was made to NSW Treasury, via OEH, for the entire $8 million. In
April 2013 the Board received advice from NSW Treasury that it had agreed to fund 50 per
cent of the estimated total cost of the project, with $2 million being allocated in FY 2013/14
and $2 million in FY 2014/15.
The remaining $4 million funding was provided through the Department of Infrastructure and
Regional Development’s, Regional Development Australia Fund (RDAF) Round 5B and
confirmed in late 2013.
CURRENT POSITION
In April 2014, GHD were awarded the investigation, design and environmental assessment
contract for the project at a cost of approximately $120,000. This investigation work has
been completed. The concept design work has also recently been completed.
Re-Surfacing Works
The following summarise the main recommendations regarding the re-surfacing works:
1. The structural capacity of the existing runway and most of the taxiway is adequate for
the projected aircraft loading.
2. The resurfacing options considered included bituminous spray seal and asphalt
overlays of 45mm and 80mm thickness. The 45mm asphalt overlay option is likely to
fit the budget and its technical benefits outweigh the bituminous spray seal.
3. Grooving of the asphalt overlay is required to conform to the requirements for skid
resistance during rain events.
Surface Drainage Works
The geotechnical assessment has found the existing pavement granular materials and
groundwater drainage conditions are unlikely to contribute to the observed poor condition of
the runway seal. As such, changes to the pavement basecourse or installation of subsurface
drainage adjacent to sealed surfaces, is not considered necessary for the runway.
The investigation results support the theory that the ‘blistering’ of the Lord Howe Island
runway and taxiway seal is not caused by hydraulic pressure (water) but rather pneumatic
pressure (air) as a result of rapid drops in atmospheric pressure, leading to higher relative air
pressure beneath the pavement seal and lifting. Pressure caused by trapped water or air
from a rapidly rising groundwater table beneath the runway is considered an unlikely
mechanism given the depth of the water table beneath the runway, higher permeability of the
natural sands beneath the basecourse and the broad lateral extent of the natural sand.
The following summarise the main recommendations regarding the drainage construction
works. Attachment A describes the works on an aerial photo.
1. Deepening the existing swale/table drain for 195m from the existing box culvert under
the airport entrance road towards Blinky Beach.
2. A reconstruction and deepening of the swale/flow path extending from the Blinky
Beach end of the runway to opposite Waimarie.
3. Construction of a new box culvert under Lagoon Road opposite the Blinky Beach
parking area.
4. A reconstruction and deepening of the swale/flow path extending from opposite
Waimarie to the inlet structure at the western end of the runway.
5. Installation of two 600 mm diameter pipe stubs through the eastern wall of the inlet
structure at the western end of the runway to drain the swale constructed as part of
(4). Floodgates installed to restrict the potential inflow of saline water into the swale.
6. Provision of a Hume Tide King (or equivalent) style of floodgate on the outlet of the
pipe under the western end of the runway.
7. Maintaining the dune level for the drain at Cobbys Beach at a level below 2.9 mAHD.
It currently sits at 3.9 mAHD.
8. Reshaping, where required, the edges of the runway to provide a quick drainage of
surface waters.
9. Regrading the swale that extends westward from the taxiway to the pipe under the
runway near Cobbys Beach.
10. Regrading the eastern side of the taxiway to drain toward the east.
The selected works will provide a significant improvement in the drainage of surface waters
whenever the swell conditions do not preclude gravity drainage of surface waters. The
selected works would provide a significant enhancement of the drainage of ponded water off
the airport and surrounds following high swell conditions.
Proposed Runway Closures
The proposed periods during which airport operations would be affected are summarised
below:
1. CLOSURES - ASPHALT PLACEMENT (except emergencies)
a. Mon 8 Jun – Thu 11 Jun
b. Mon 15 Jun – Thu 18 Jun
c. Mon 22 Jun – Thu 25 Jun
d. Mon 29 Jun – Thu 2 Jul (CONTINGENCY)
During the runway closures above, the runway would be made available for
emergency landings from general aviation and medical evacuation. The exact time to
return the runway to service would have to be determined in consultation with the
Contractor. Returning the runway to service in an emergency or at the end of each of
the three stages, would require a wedge or ramp of asphalt to be laid to smoothly join
the new and existing surfaces.
2. OPEN - LINE MARKING & GROOVING
a. Fri 12 – Sat 13 Jun
b. Fri 19 – Sat 20 Jun
c. Fri 26 – Sat 27 Jun
d. Fri 3 – Sat 4 Jul (CONTINGENCY)
3. OPEN SUNDAYS WITH NO WORK PLANNED
These dates represent the best estimate at this stage and would be further refined as
detailed design is completed and construction tendering is completed. They key risk is that
the delivery of materials to the Island is not achieved by the early June start date.
There remains the possibility that nightwork could be carried out as a further contingency in
the program.
Cost to Complete Estimate
A preliminary cost estimate has been completed for the completed concept design. There
are some significant qualifiers attached to the estimate and it represents a fairly conservative
position.
The estimated design and construction cost of the project is $7.5 million. A contingency of
$1.5 million (20%) on top of this has been allowed to reflect the early stage of design and
quantity estimates. The total project value is therefore $9 million.
Based on the concept design presented and taken into consideration the conservative
nature of the cost estimate, the project budget of $8 million will be under pressure
throughout the remainder of the project. However, there will be opportunities to reduce the
scope of work for the project as the design is progressed if the risk to the budget becomes
too high.
Next Steps
A community information session is planned for 17 September to discuss the
recommendations of the reports, the project timing and seek feedback from the community
on the proposal.
Following this session, the detailed design will be finalised and the environmental
assessment will be completed to allow submission of a DA to the Board.
Under NSW Government guidelines, construction projects valued at over $1 million require
an accredited project manager to oversee the project. The Board is not an accredited project
manager, so a consultant project manager is to be engaged to manage the project alongside
the Manager, Infrastructure and Engineering Services. This project manager would be onsite during construction to supervise and manage the works. A request for tender for this role
has been issued to three consultants and following a tender evaluation exercise, a contract
is expected to be awarded in early October.
Funding through the RDAF has not been received as the department’s guidelines require
that projects be ‘tender ready’ before the final application is assessed and the funding
delivered. The project should be ‘tender ready’ in late October 2014.
Award of the main construction contract is expected in March 2015 and mobilisation of the
estimated 9,000 tonnes of materials and equipment will be undertaken through March–May
2015. Construction works will be undertaken through late May–early July. All equipment and
materials would be removed from the Island by early August.
RECOMMENDATION
It is recommended that the Board note the above information and
1. Approve the Board administration to commence discussions with stakeholders
regarding the runway closure periods.
2. Approve the community information session to proceed on 17 September with the
completed concept designs and runway closure periods.
Prepared __________________ Andrew Logan
Manager, Infrastructure & Engineering
Services
Endorsed __________________ Penny Holloway
Chief Executive Officer