Challenging services upgrade

By and - , Build 188

Digging up the past can be a journey into the unknown as evidenced by a recent project upgrading the underground services in the iconic Auckland Lysaght Building while maintaining business as usual.

MOST GREENFIELD construction projects tend to be straight-forward in terms of what needs to be done and what it will cost. There may be changes and cost fluctuations during the project life, but generally these will be acceptable and manageable if the scoping work has been thorough and the costings accurately determined.

Remediating existing underground services

Upgrades or remediation works on existing buildings – particularly major works – can be more testing. As old structures are peeled back – walls stripped, ceilings opened, floors uplifted – the true nature of any problems, such as unexpected asbestos, can be revealed and requirements can alter. Often, added complexity can emerge.

But the level of uncertainty around what needs to be done takes a big step up when upgrading underground services, such as old sewage systems buried under concrete, in a large heritage public building that itself is not being upgraded and needs to keep operating.

That was the challenge facing the team at Eke Panuku and Quantity Surveyors and financial management partners Kwanto when a significant underground services upgrade was required at one of the oldest buildings in Auckland’s Wynyard Quarter – the Lysaght Building, established in 1927.

Substantially refurbished in 2015, the Lysaght is an important fixture in the precinct. It is an Auckland Council-owned commercial space featuring a café, event spaces for public use, mobile workstation areas and other public and private facilities, including GridAKL and University of Auckland offices.

Upgrade to meet modern demands

However, like many buildings that can boast 100 years of existence, the Lysaght had aged underground services that could no longer cope with the demands of the 21st century. That was evidenced by repeated sewage system blockages that were temporarily remedied in late 2019, but it was clear a more permanent solution was needed.

Eke Panuku and Auckland Council’s Amenities and Infrastructure Maintenance Services (AIMS) business unit contracted Seger Group to scope the requirements to upgrade the old sewerage and complete the work. Kwanto’s role was to review the tender prices for the work and financially manage the project to completion. Engineering consultancy Tonkin+Taylor was appointed to provide contaminated land and civil engineering design services.

Challenge of maintaining business as usual above

From the outset, the difficulties presented by the upgrade were obvious – sewage pipes needed to be laid inside and underneath the building and connected into the public sewage line under the adjacent street, all while maintaining the Lysaght as open for business. That meant scheduling the interior works to only take place between Friday evening and late Sunday night to allow undisrupted commerce in the building during the working week proper.

But the Lysaght is not a 9-to-5 building. The event spaces are often used for night meetings or weekend gatherings and conferences, so working around those needs was a delicate balancing act, calling for regular communication and consultation. Strict noise controls also applied – minimal noise inside the building while tenants were there and no more than 65 decibels externally.

Two significant issues found

When the construction team dug down into the floor, they struck two significant issues that necessitated a change to the originally proposed replacement methodology. They found a large mass of concrete in the way and contaminated fill around the old pipes – a legacy of some of the early industrial operations on the waterfront, which included a tannery.

The concrete mass severely limited access to the work area to less than 1 m inside the boundary, which slowed progress. It also complicated the removal of the old pipes, which were embedded in the concrete.

In addition to determining the engineering solutions to the project challenges, Tonkin+Taylor also managed the contamination issues, which required a HydroVac excavator to be used to suck out the contaminated fill.

Adjacent footpaths needed to be dug up to access the exterior connections to the sewer system, requiring a traffic management plan, and when those services were revealed, their extent was much greater than originally thought. Given the original construction was almost a century ago, the as-built paperwork was sparse and use of ground-penetrating radar to review the private sewer alignment proved futile because of the thickness of the concrete floor within the building.

The slope (gradient) of the main sewage pipe was also inadequate and had to be corrected with the replacement. A section of the new sewer pipeline also had to be thrust approximately 2 m beneath a concrete rain-garden structure between the sidewalk and the road.

An additional requirement was to ensure the interior finish was aesthetically pleasing – the new concrete floor, for example, needed to match the old undisturbed floor.

Timeframe extended due to COVID-19

The unexpected conditions, the construction challenges, the workspace restrictions and other complications meant materials and labour costs had to be regularly reviewed and revised.

The original project timeframe was estimated at 2 weeks, but that grew to 4 months, largely because of COVID-19-related impacts, the unexpectedly difficult ground conditions and underlying services complexities and challenges. The project commenced in Easter 2021, and the main work was expected to be finished in September, but final completion was delayed by lockdown.

Costs were initially calculated on the understanding that this was a provisional figure and could increase once the site was excavated. As the works were on an existing and old building, risk analysis and contingencies were applied and regularly reviewed. Understandably, the cost of the project increased compared with the original estimate.

There was a great deal of satisfaction, however, among the project team and partners in overcoming both the challenging environment and the shifting scope to deliver a high-quality outcome for this iconic Wynyard Quarter landmark building and its tenants and users.

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