The Hunua project is the biggest water
pipeline project undertaken in New Zealand for many years and
involves 30 kilometres of 1.3 to 1.9 metre diameter steel pipeline
traversing Manukau and Auckland cities. It involves the crossing of
Manukau Harbour, three motorways, three railway lines, a creek and
eight streams.
GHD was engaged in 2005 to carry out an
options study for a new watermain from ‘southern sources’ to ‘city
centre’. As a result of a competitive tender, GHD was jointly
awarded the design contract in strategic partnership with
engineering consultancy CH2M Beca in 2008. GHD services
include:
- Overall project coordination and management of options
study
- Preliminary planning and environmental assessment of multiple
route options
- Options feasibility investigation
- Issues, options and constraints evaluation (environmental,
social, economic and cultural)
- Consenting strategy and stakeholder management and coordination
of specialists for AEE and consenting applications
- Consenting within existing and proposed urban residential,
commercial environments, rural, open space, coastal waterways,
scheduled heritage sites, protected vegetation & ecological
habitats
- Stakeholder and public consultation assistance
- Pipe materials study, valves and other equipment selection
- Survey, constraints mapping and reporting (GIS)
- Concept and detailed design of large diameter bulk
watermain
- Cathodic protection design
- Construction methodology development including Trenchless
methods
- Cost estimation and quadruple bottom line reporting
- Risk management
- Procurement strategy development and procurement
management
- Tender, construction supervision, contract administration,
testing and commissioning
In the early stages, GHD’s planning,
hydraulic, environmental and geotechnical engineering specialists
developed preferred options involving key stakeholders. It was
essential that this process bring these stakeholders along for the
journey, taking into account the quadruple bottom line approach to
delivery and positive community and stakeholder outcomes. GHD
delivered an options report to Watercare in 2007 evaluating 50
proposed routes for the watermain. Initially a total of six options
for meeting project objectives were provided to Watercare.
GHD initiated the consultation from the
options development phase through to consenting in 2009. They
prepared consultation material and liaised directly with three
consenting authorities, NZHPT, ONTRACK, NZTA, iwi and other
interested community groups affected by the project. A holistic
project approach and commitment from the GHD team provided a
streamlined and ‘consentable’ option which minimised the impacts on
the environment.
In late 2008, GHD and Beca started the
detailed design, consultation and consenting phase and successfully
completed consultation strategies and action plans that supported
the RMA process. Through identifying these areas early and
addressing them via a constraints evaluation process, the GHD team
further refined the route alignment and construction of the
pipeline to address sensitive coastal environments. They
worked in the vicinity of Auckland International Airport, NZTA
state highway designations (1 & 20), scheduled heritage sites
and sites of cultural significance to iwi.
The Hunua 4 pipeline will run through the
heart of the city and a construction corridor will run past the
front doors of approximately 5000 properties. There were a
number of challenges including:
- Producing design options that could be successfully defended at
hearing
- Ground conditions that varied from soft peats to hard
basalts
- The minimisation of traffic disruptions and environmental
effects
- The integration of Hunua 4 with existing reticulation
- The identification and protection of other services
- The design of Hunua 4 to allow future roading upgrades
- The establishment of clear lines of communication to ensure
everyone affected by the project was fully informed
First stage construction, the section
incorporated in new Manukau Harbour Bridge, started in October 2009
and was completed in July 2010. Preliminary design of the remaining
route was delivered in Nov 2009 and detailed design is now
underway. Notice of Requirement (NOR) and Resource Consent
applications were lodged in March 2010. Affected parties were
notified in May 2010. The Hearing was held in August 2010. A
crucial connection to Hunua 3 in Onehunga is programmed for June
2011.
The main construction contract(s) is
programmed to start in early 2012 and final commissioning is
expected in 2016.
When completed, this project will
substantially improve security of water supply to the city’s 1.3
million people. The lifetime of the Hunua 4 watermain is estimated
to exceed 100 years, and its functionality, design and structural
integrity is of significant importance to Auckland and New
Zealand.