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Piritahi is undertaking trenching works in several neighbourhoods to prepare for the undergrounding of power and communications lines

Faster housing requires faster infrastructure

As population and housing density increases, so too does the demand on infrastructure. Piritahi is an alliance of infrastructure and land development experts working collaboratively to design and construct projects using a faster, more efficient approach.

Recently described by Infrastructure NZ CEO Paul Blair as simply ‘a tool for creating wellbeing for people’, infrastructure is the systems and networks integral to the safe and comfortable functioning of communities. These include transportation networks such as roads, cycleways and walkways, and access to utilities such as telecommunications services, water and sewerage systems, and electricity.

Most of Auckland’s infrastructure was built before the intensification the city is experiencing had even been considered. Fast-forward several decades and the city has a network not designed for today’s population, let alone higher density.

Basalt poses its challenges in Owairaka where Piritahi is constructing a dedicated stormwater network to reduce wastewater overflows into Oakley Creek

Our lives and needs have also changed. For instance, not only do we need more transport infrastructure, but a variety too. Our lifestyles call for alternative modes of transport like cycleways and more walkable neighbourhoods, while our increasing reliance on technology and telecommunications feeds an appetite for speedy, failproof electricity and broadband networks.

Infrastructure also needs to withstand environmental extremes. Today, modern standards require robust networks that can cope with severe weather events such as extreme downpours, yet outdated infrastructure remains in many places across Auckland. Combined stormwater and sewer networks mean that oceans and waterways can experience wastewater overflows from many urban neighbourhoods – the same neighbourhoods where infrastructure like overhead power lines pose a hazard and are subject to interference. Piritahi is playing a vital part in solving constraints like these to help unlock the city’s housing provision.

Focusing on ‘future-ready’ infrastructure, Piritahi is delivering systems and networks that are modern and capable of meeting communities’ needs for decades to come. From the separation of combined stormwater and wastewater networks, to the undergrounding of power and communications lines, through its design and construct alliance model and an ‘at scale and pace’ mindset, it is also doing it faster and more efficiently than the old ways of working can achieve.

Who is Piritahi?

Piritahi is an alliance of companies formed to streamline land development, enabling more homes to be built, faster. Kainga Ora – Homes and Communities is the owner-participant and masterplanner. Non-owner participants are design consultancies Harrison Grierson, Tonkin + Taylor and Woods, alongside civil contractors Dempsey Wood and Hick Bros Group. Chosen for their track records and connections to the wider civil engineering and construction industry, Piritahi offers huge capability to deliver everything from pipes, roads and bridges, to walkways, parks and public spaces.

Land development and civil engineers work together with constructors to design and deliver projects

Unlike other alliances that deliver one specific project, at any given time Piritahi handles multiple smaller projects across several locations, each with their own target outturn cost (TOC). A robust and agile project delivery team is designed to deal with these complexities and to scale up.

It is estimated that Piritahi will complete over $1 billion worth of infrastructure and land development work over its lifetime, spread across hundreds of individual projects. Laying the groundwork for the Government’s large-scale redevelopments across Auckland, projects currently under civil design and construction include those in Northcote, Mangere, Oranga, Roskill South and Owairaka, where thousands of new homes will be built over the next several years.

The alliance’s specific responsibilities are wide-ranging and include site investigations, detailed civil design and construction, the removal of old state houses, land remediation, arranging resource consents, creation of new land titles, and the construction of infrastructure, public spaces and other amenities – all while engaging with and looking after the communities they’re working in as they go.

A robust, independently verified commercial model, along with embedded systems and significant in-house training capability, provides a rapid mobilisation platform to expand with project demands. With an existing pool of pre-qualified suppliers and subcontractors, Piritahi is steadily growing the industry and achieving cost efficiencies through the sheer scale of its programme of work.

From masterplanning to delivery

Piritahi is working in several major developments across Auckland in parallel. Kainga Ora works with urban designers to create a masterplan depicting new land parcels, or ‘superlots’ in each of these. The masterplan also depicts new or upgraded assets like roads and pathways, and amenities such as parks, greenways and playgrounds.

Piritahi works closely with Kainga Ora to deliver each masterplan by assessing, designing and delivering the civil infrastructure requirements that future communities will ultimately need. This is done using any existing data, and by gaining more through conducting a range of site investigations and surveys.

The information captured helps to determine the condition and capacity of existing land and infrastructure, whether it can support an increase in new homes, how much of an increase, and of what typology. Factors like geotechnical conditions, how much traffic local roads and footpaths can accommodate, whether the local sewer and stormwater network can service a community into the future, and if the current water supply network is sufficient are all considered. The answers to these questions and others like them inform what Piritahi’s civil and land development engineers design and ultimately construct.

At any given time, Piritahi is working within residential land and in public spaces throughout many areas of several neighbourhoods. Piritahi utilises global consenting to save time and money, and to minimise the disruption of multiple construction activities in the neighbourhoods, ultimately delivering land that is ready for new, warm dry homes.

Surveying at scale and pace

In every neighbourhood destined to be redeveloped, Piritahi’s surveyors are often the first ones in and last ones out. The data they capture identifies ground levels and slope, and precisely locates existing features and services. This information allows their civil and land development engineers to design and construct effective solutions down the track.

From a construction perspective, surveyors take engineering designs and translate them into information to be used on the ground. They mark out where everything that has been designed should be constructed, and come in again post-construction to record the exact location of where things were built.

Surveyors also deal with the legal side of things, drawing attention to any pertinent interests that the land may be subject to, and creating boundaries to use for new land titles.

Piritahi’s surveyors are first in and last out, capturing data to help its engineers design and construct future-ready infrastructure

With the huge scope and scale of Piritahi’s programme, the volume of survey work ahead is immense. Before redevelopment activities can commence, existing ground levels, current infrastructure, and boundaries need to be captured across several urban environments. Data then needs to be captured again at various trigger points once physical activities have taken place.

Piritahi engages people at its member companies to perform a lot of this fieldwork – access to talent and resources is just one benefit of ‘alliancing’. But given the volume of work in the pipeline, to carry out all fieldwork conventionally and continue to deliver at scale and pace would be impossible. Fortunately, there are now more innovative methods available. By utilising LiDAR, mobile laser scanning, UAV (drone) and other GPS-driven technologies, engineering design and construction progress can happen faster and in a much more streamlined way.

Piritahi is also working towards processes that cut out the requirement to compile reports and plans. With the help of their in-house geographic information system (GIS) team, surveyors can transfer data straight from the field into a GIS system where it is accessible across the alliance teams and disciplines.

By combining these innovative methods, Piritahi will be able to cover a huge proportion of survey fieldwork extremely efficiently, helping to deliver build-ready land at an ambitious scale and pace.

Land remediation

A significant part of Piritahi’s role in preparing land for new homes is the remediation of it. Land is remediated with one overarching objective – to make land safe and sustainable for construction workers and future generations of residents.

Although Piritahi is working with land that has generally been used for state housing, all of Auckland’s land has been impacted by human use. Building practices and materials commonly used in the past, such as lead paint and asbestos, have affected the soil that many homes were built upon. Piritahi’s land remediation team test each of these sites and safely deal with any impacted soil before construction begins.

Levels of lead in soil vary from property to property. One of the reasons for such differences can be attributed to the varying maintenance levels that have occurred across different properties. Sites with higher levels of lead, for example, may have been painted with lead paint more frequently, or painters may have been less diligent about removing sanding dust.

Undertaking infrastructure projects in brownfield environments poses logistical challenges, often requiring road closures and working with residents to minimise disruption

Another source of contaminants is building or domestic waste. A common practice in the past was to throw waste material generated from building a house (offcuts) into the trenches that form the home’s foundations. Uncontrolled filling and disposal of domestic waste has also occurred in some areas of Auckland.

Piritahi has also found very low levels of asbestos in some soil being tested across sites. Traces of asbestos can stem from rainwater running off asbestos roofs, or from fragments of broken roof tiles, cladding and fencing being buried over time in the soil of these properties.

When levels of soil impaction are above the conservative thresholds set by Piritahi, anything from 100 mm to as much as half a metre of soil is often scraped off the surface and removed from the site, or in some instances can be encapsulated and covered with fresh soil. Topsoil is also often added at the end of the building process in areas where landscaping activities follow.

Piritahi and Kainga Ora set a highly conservative approach to land remediation. Safety is top priority – it is vital to make sure that workers developing the land, and its future residents, are not exposed to highly impacted soil. Effective land remediation also ensures that rainwater runoff entering the stormwater system doesn’t negatively affect the environment.


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