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Massive storage compound fuels the South Island


29 September 2020

Improved fuel supply capacity for the South Island was achieved with Citycare Property’s successful construction of major upgrades to Mobil Oil New Zealand’s storage tank compound in Lyttelton.

The complex, three-year tank storage project at the Christchurch port involved an astounding amount of poured concrete.

More than 2,000 cubic metres of concrete was placed above ground, and over 6,000 cubic metres below ground, by the Citycare Property team at the Mobil terminal on George Seymour Quay.

In total five new storage tanks were constructed – one for petrol, another for diesel, a blending tank and two water storage tanks for fire-fighting purposes.

Work on the project began with ground improvement trials in July 2017 and continued through to the completion of construction in February this year, Structures Contract Manager Chris Pinion said.

It was a challenging and complicated project. The massive volume of concrete was used to build the five tank foundations, external and internal containment walls, ground improvement columns, foundations for the pump house building, pipe support, gantry shelter, and other various foundations.

The Mobil compound is surrounded by a 2.7-metre high bund wall and lined with nearly 7,000 square metres of clay liner to be virtually water tight. This is to protect the environment in the event of any accidental spill within the site, Chris says.

Mobil Civil diggers

Two diggers working on the compound liner with two of the new tanks in the background.

There were many challenges in this project, not least the unexpected five months of major spoil removal undertaken before the works could begin, he says.

To overcome challenges presented throughout the project, there was a lot of collaboration between Mobil, project designers and Citycare Property to implement solutions efficiently to allow the project to progress while minimising the impact on cost and timing, he says.

The site is located on reclaimed land made up of marine silts, so significant earthworks were required to stabilise the site for the use of heavy equipment, particularly once the surface hard fill had been removed.

Then the weather threw in a few curveballs – 2018 was one of Canterbury’s wettest years recorded which made the earthworks at the start of the project challenging and huge excavating equipment was not immune from getting stuck in the mud.

The presence of fine clay and marine silts on the site made cleaning water that collected on site challenging.

A temporary 200-square-metre, two-stage containment pond was constructed and specialist dosing and filtration equipment put in place to ensure that the water being discharged from the site was clean and not harmful to the environment.

Citycare Property’s extensive planning, impeccable standard of quality assurance and impressive safety record helped ensure the success of the project.

“The accuracy of Civil’s construction was of an extremely high standard. This was important as others had to use our foundations to undertake the mechanical construction elements following our works,” Chris says.

“The tank foundations have performed exceptionally under load testing and once in operation.”

Also, water containment tests in the new compound were very successful, Chris says.

To test the water proofing performance, the compound is filled with water and loss measured by a specialist contractor over a minimum of 24 hours. The tests produced results that far exceeded the minimum loss requirements, in fact five times better than is allowable.

Mobil containment testing

Water containment tests at the compound were very successful.

An exceptional safety record was maintained on the site with no lost time injuries and only six minor injuries recorded throughout 80,000 work hours. That’s the equivalent of one person working full-time for 35 years!

Citycare Property adopted Mobil’s stringent safety processes for the execution of this project and the team adapted well to the site-specific requirements, as the safety record shows.

Concurrent execution of civil and mechanical works by separate contractors at the site meant collaboration was a key component of success for the team.

“For example, daily planning meetings were held at a supervisor level with representatives from Mobil, Citycare Property and the mechanical contractor to ensure coordination of activities across the site,” Chris says.

Congratulations to the Civil Structures team for the fantastic work on this lengthy and complicated project connecting communities in the South Island by building this massive fuel supply compound.

Mobil overview completed project

A bird’s eye view of the site of the storage tank compound upgrades completed by Citycare Property for Mobil Oil New Zealand.