28 November 2023

Top photo: temporary staging progress, bottom photo: progress looking towards Stillwater.

Noema | November Construction Updates

State Highway 1/East Coast Road

Wick Drains:

• Construction of a sand blanket layer and sub-soils, followed by the installation of the wick drains has been completed. The wicks provide a channel for water to be removed from the soil helping to prepare the ground faster.

General works:

• Continued construction of erosion and sediment controls.
• Constructed haul roads for our earthworks.
• Piling works to support the East Coast Road Bridge construction.
• Relocated underground services.

Ara Wēiti Road

• Constructed temporary stream diversion.
• Completed construction of main project office.
• Continued earthworks and ground improvements in the Ara Wēiti forest area.

Stillwater

Wēiti River Bridge temporary staging:

• The works on the western side of the river continued with 12 of 25 bays of temporary staging completed. The staging you can now see in the river will be used to construct the permanent bridge.

Wēiti River Bridge western abutment:

• Installed 13 of 35 of 900mm and 1200mm diameter steel reinforced concrete piles to strengthen the ground.

Duck Creek Road west:

• Large earthwork machinery started the first permanent cut to fill works.
• Access track, ground improvements, tree clearing and erosion and sediment control construction continued to support our earthworks.

Whangaparāoa

Vegetation and tree clearing:

• Tree clearing continued as areas are checked and monitored by the ecology team.
• Chipping and stump grinding work continued.

Wick Drains: 

• Construction of a sand layer and sub-soils commenced followed by the installation of wick drains.

Check out more progress photos on our website.

Left photo: Duff made from vegetation we harvested and existing topsoil. Right photo: dedicated Duff trial area on site.

Duff: Turning Over a New Leaf

The transport sector presents huge opportunities to better protect the environment and support the move to a more resilient world. For example, landscaping along roads and highways, such as O Mahurangi - Penlink, often involves layers of topsoil, mulch, and native plantings. Whenever there isn’t enough topsoil available, it's common to import both topsoil and mulch to create a stable growing environment for new plants. This method often leads to numerous truck movements and diesel usage and if used, would contradict our aim to reduce carbon emissions.

We recognise the importance of using innovative solutions, and are trialling an ecological soil mix called Ecological Mulch Duff Topsoil (EMDT or Duff for short). Duff is the partly decayed organic matter found on the forest floor. On our project, Duff is the vegetation we harvested on-site blended with existing topsoil. For this reason, if you are driving through the project area you may notice felled vegetation and trees left behind. Don’t worry - this is all part of our plan to reuse vegetation and create Duff.

To make Duff, we will mulch around 50% of the felled vegetation into rough material. We will keep the remaining 50% as larger logs which are stabilised. These logs serve a dual purpose in landscaping. They provide microhabitats for planting and offer natural habitats for fauna. We will also use tree trunks and root balls for stream restoration efforts, creating freshwater habitats.

Using Duff has many environmental benefits, including:

• Reduces emissions by importing less topsoil and mulch.
• Reduces waste by keeping green waste and felled vegetation on-site.
• Preserves native seed source from felled vegetation and soil on site.
• Provides more biodiversity within the project area.
• Enriches the soil, providing a beneficial environment for soil microbes. They will help release nutrients from the woody material in soil over time.
• Creates habitats for fungi, microbes, and animals by placing logs on top of the Duff to decay over time.

We are proud to be the first infrastructure project in the country to use Duff. To ensure the effectiveness of this new approach, there is a dedicated trial area on-site. It is a great opportunity to collect good data and share our findings. We also planted in the trial area to ensure we know how plants will react and grow in this new medium. The trial gives us an understanding of the seed source (pest plants and natives) within Duff. We will use it to manage native and pest plant regeneration.

By using Duff, we are rethinking conventional methods and setting a new standard. The contributions we make now towards reducing our emissions in the transport sector can carry a big impact.

Approximate raised crossing location in red on East Coast Road.

Traffic Changes Coming to East Coast Road

With the start of a new earthworks season, you will soon see work beginning on the new overbridge at East Coast Road.

To protect the underground services on East Coast Road, we will be installing a raised crossing to allow heavy construction vehicles to cross from one side of the road to the other.

To ensure the safety of road users when construction vehicles cross, a 30km speed limit and temporary traffic signals will be in place and operational during work hours  (Mon – Fri:  7am to 6pm Sat:  8am to 4pm). The traffic lights will remain green until a construction vehicle needs to cross.

The raised crossing will be constructed during the day on Thursday 7 and Friday 8 December under stop/go traffic management with a 30km speed limit. The traffic lights will be operational from Monday 11 December.

We aim to minimise disruption as much as possible to road users. Please take care when travelling through our site and abide by all road rules.

Harakeke harvested by our kaitiaki along the O Mahurangi alignment.

Harakeke: A Cultural Treasure Reimagined

Harakeke, also known as New Zealand flax (phormium tenax), stands as a revered native plant in Aotearoa New Zealand, holding profound significance within Māori culture. Beyond its cultural eminence, harakeke boasts numerous practical applications—from clothing, mats, and baskets to ropes, fishing lines, and medicinal remedies. Even the nectar from its flowers was used to sweeten food and beverages.

In the ethos of Te Ao Māori, the harakeke plant beautifully symbolises the concept of whānau, the family. The rito (shoot) embodies the child, nestled protectively within the awhi rito (parents), while the outer leaves represent the tūpuna (grandparents and ancestors).

Recently, a section of harakeke needed removal along the alignment of O Mahurangi. Rather than discarding it, our project's kaitiaki—a guardian with deep cultural ties—embarked on a culturally respectful harvest to repurpose this cherished plant in innovative ways, honouring its familial representation.

In our Culverts – Fish Passage:
The kaitiaki meticulously crafted a long rope from the harakeke and strategically placed it within several culverts. This alternative serves as a fish passage method, offering an eco-friendly substitute to conventional fish ladders, facilitating the migration of our aquatic friends over or around obstacles.

In Our Moana - Kohunga Kūtai:
Portions of the harakeke from O Mahurangi have contributed to an ongoing external research project. Collaborating with scientists and experts, these natural fibres are being explored as a potential replacement for plastic mussel spat rope. Annually, the green-lipped mussel aquaculture industry heavily relies on plastic ropes to capture wild mussel spat for farming purposes across Aotearoa New Zealand. Yet, concerns arise regarding the environmental impact of these plastic ropes when lost at sea or disposed of in landfills due to limited recyclability. More info here: https://www.learnz.org.nz/sustainableseas221

This innovative endeavour not only showcases the adaptability of harakeke but also honours its cultural roots, recognising its representation of family within Te Ao Māori while offering sustainable solutions for contemporary challenges.

Tracking our Sustainability Progress

We recently published our 2023 Sustainability Annual Report online and are happy to share more about our progress so far. To recap, our project sustainability targets include:

• Using 10% less embodied carbon in core structural materials.
• A 10% reduction in energy consumption throughout the construction and operational phases.
• Using more than 10% of materials with recycled content.
• Diverting over 80% of clean spoil (aiming for 100%) and 90% of inert and non-hazardous waste (construction waste) from landfills.
• Diverting 60% of office waste from landfill.
• A 10% increase of non-potable water usage for construction purposes.

So far there have been over 30 sustainability opportunities realised across the project, including:

• Wēiti River Bridge: Our innovative design reduces carbon emissions by shortening the span and optimising its structure. This minimises materials needed.
• Grass Turfed Bunds: By using topsoil and turf layers, we've minimised the need for geotextile fabric. This reduces landfill waste.
• CCS Candy and Carbon Factors: Carbon factors are now included in CCS Candy, a cost estimating software for the project. This identifies the carbon footprint of materials and tracks carbon for the project.
• Electric Vehicles: Using electric vehicles on-site has cut down on carbon emissions.
• Sustainable Catering: We use The Sustainable Food Company, a zero-waste caterer, to help us reduce waste at events and promote sustainability.

Read the full Sustainability Annual Report Summary here.

Sustainability Team, from left to right: Amanda, Fiona, Liz, and Lucy.

Staff Spotlight: Sustainability Team

This month our newsletter is full of our sustainability progress and how we are pioneering a new way of building infrastructure. We have a small but mighty team that champions sustainability here at O Mahurangi. Read on to learn more about them:

Amanda, Sustainability and Carbon Advisor, is collating and coordinating the Infrastructure Sustainability Council (ISC) V1.2 Design Rating submission, with the aim to get at least an 'excellent' rating. This includes seeking and co-developing evidence for meeting different credit criteria for the rating, working closely with several disciplines. Amanda also helps with achieving and reporting on broader sustainability outcomes on the project, including creating a sustainability culture by identifying initiatives and processes to reduce carbon, waste or water, and working closely with the site Environmental and Sustainability teams.

Fiona, Sustainability Consultant, is collating information and evidence, and preparing documentation to go towards the project’s ISC Design Rating. Fiona works closely with the team to support rating requirements as well as broader sustainability initiatives.

Liz, Sustainability and Climate Change Lead, has over 18 years of experience working in sustainability in the built environment - in design, construction, facilities management and Non-Government Organisations sustainability framework management. On the project, she oversees the Sustainability Team and is responsible for the ISC Design submission.

Lucy, Sustainability and Carbon Advisor, is responsible for collating information for the ISC Design Rating especially for the energy, water and material base case’s credit criteria. She works closely with Amanda and supports with rating requirements as well as broader sustainability initiatives.

Weathering the Storms with NIWA

NIWA stands for the National Institute of Water and Atmospheric Research. They are a Crown Research Institute established in 1992. Their environmental science work enables the sustainable management of New Zealand's natural resources. We recently partnered with NIWA for more reliable weather forecasting.

NIWA provides us two weather forecasts a day, made up of 18 different models. The forecasts give us more confidence than what is publicly available. We then share these with our construction team, so everyone knows what weather is expected.

More reliable weather forecasting means:

• we can prepare our site and the erosion and sediment controls accordingly.
• we get the best possible performance out of our erosion and sediment control devices.
• we can prioritise maintenance, installation of devices and opening up new work areas.
• less surprises so we limit our environmental impact as much as possible.

If a significant weather event is coming up, we'll discuss NIWA's confidence levels and request a long-range forecast. This helps us understand what kind of recovery and/or standdown time we need to allow for.

Our partnership with NIWA helps us manage our work better and protect the environment.

Whakapā Mai | Contact Us

For more information on the O Mahurangi - Penlink project, call us on 0800 7365 465 or email us at omahurangi@nzta.govt.nz.

Visit our website: www.nzta.govt.nz/projects/penlink/