The Living Building Challenge® (LBC) Net Positive Waste imperative strives to significantly reduce or eliminate the production of waste during the design, construction, and operational phases of a project, including minimising water waste and wasteful spending on energy and resources. The intent of the waste imperative is to encourage everybody - designers, building and maintenance contractors, sub-contractors, and occupants - to have a thorough conversations about what can be done imaginatively to reduce and reuse waste materials throughout the building’s whole lifecycle.

We spoke with Max Christian, LT McGuinness Cadet and Te Herenga Waka 2021 Bachelor of Building Science graduate, about what’s happening on site to realise the net positive in waste imperative.

Could you talk through some the ways LTM are reducing or reusing waste on the Living Pā site that’s different from business-as-usual practices?

The usual waste practice within Wellington is to get a skip, because of its convenience and low cost. As part of LT McGuinness’ Low Carbon Mission, we recognise this as an issue and all of our sites are starting to divert waste where we can. However, the Living Pā takes this to another level, where all of our waste streams need to be managed and tracked by weight across all site acivities to achieve the Living Building Challenge criteria of 90% of our construction waste being diverted from landfill. As we work our way through this massive challenge, we will learn, demonstrate good practice, educate and implement across the entire company.

How we’re managing timber waste is particularly interesting. Typically, after materials have been used for constructing temporary structures, such as hoardings and formwork, they are destined for the landfill. To remove this waste stream entirely, Ben Mitchell, our site manager, has made the Living Pā an untreated timber-only site for temporary works. We’ve provided a separate untreated timber skip that gets shipped to McMuds who mulch it for spreading over playgrounds around the Wellington region. This is a nice example of repurposing a material as a secondary product. Similarly, our RDL demolition team delivered the concrete waste from site to Kiwipoint, who crush it for reuse as recycled aggregate.

You will also notice the mosaic looking fencing panels installed to the site perimeter. This product is called saveBOARD and it is recycled plastic waste manufactured into a sheet product. This will be removed at the completion of the project and again recycled to produce new sheets of saveBoard for future developments.

The Living Building Challenge requires the LTM team to divert 100% of soils and biomass from landfill. Generally, excavation fill would typically go on top of, or be spread through, a landfill. Technically this method recycles the fill because it is covering up rubbish; however, it doesn’t comply with our certification. James McLean, the Living Pā’s Project Manager, frantically rang around Wellington to find a home for the Living Pā’s clean fill. We ended up finding a developer in Ōhariu Valley that needed a few valleys filled for new developments.

Initiatives that involve refurbishment of waste produced on-site for a second purpose are other great options for our certification. For example, we have roughly 300 plus pile-offcuts that need a good home. After a bit of research, we found out that the H5 treatment only penetrates into the outer layer of the large pile-off cuts, the remaining centre is virtually untreated. We’re sending the larger pile off-cuts to be re-milled in Pāuatahanui for reuse as timber lagging on retaining walls within the development.

With many trades, subcontractor and suppliers coming and going, is the change practice proving difficult across the whole site, every day?

In regard to processing on-site waste, LTM has appointed Waste Management (WM) to deal with processing certain commercial waste streams. The key difference from our standard day-to-day activities is a requirement to report/document all waste diverted or taken to landfill and provide proof of receipt or dockets from the reuse provider. WM can offer separate waste skips that are supported with educational material, such as signage and videos. All waste taken from the site is weighed either via a weigh station or directly from the WM truck which is then provided to LTM to define the waste stream, weight, where it was recycled, and receipts that match the data.

This project is a step in a new direction for the construction industry, which is hard to explain sometimes to new trades personnel and suppliers. On-site we’re providing a lot of educational material and developing relevant toolbox talks to help educate people about why we’re pushing so hard for recycling on-site. Generally, the buy-in comes after they understand their contribution matters to the project.

We are also reaching out to merchants and suppliers to explain that the Living Pā is a different site and the project certification criterion we are facing. For instance, a lot of materials come on to site in plastic wrap, such as treated timber, and we’re asking our suppliers not to wrap their products. Eliminating or reducing packaging has been easy to implement and reduces unnecessary waste on-site.

What are the lessons you’re learning?

Almost always someone from the industry has dealt with a similar issue in the past, in some shape or form. We’ve reached out to waste users, subcontractors, suppliers and staff to find solutions for waste streams that don’t have the commercial recycling infrastructure in place. Our health and safety manager mentioned that our ‘un-millable’ timber pile off-cuts could potentially be used for mountain bike ramps. After further investigation, we’ve been able to team up with Mākara bike park and to date have supplied them with 2.2 tonnes worth of off-cuts to use in the construction of their skills course tracks.

You can always expect some teething problems. People will inevitably make mistakes so we’re trying to reiterate the message of recycling positively. You’ve got to take a step back and understand this is a new path for the industry and we’ve got to support everyone on site to understand their waste streams and the positive impact that they can have. Hopefully by being involved in the Living Pā people will want to take what they have learnt to their next project and share the lessons learnt with their teams.

Do you feel like you’re going to achieve the LBC targets?

Our teams are super passionate about the Living Pā and with the support from our wider L.T. McGuinness whānau, partners and Te Herenga Waka, we’re certainly giving it our best effort.

He whakautu pai!