Australia’s kwik-ZIP and the case of San Francisco’s sinking Millennium Tower

San Francisco is known worldwide for its attractions such as the glittering red wonder of the Golden Gate Bridge from which travellers can look out upon the San Francisco Bay.

301 Mission Street is getting a helping hand from Australian-owned kwik-ZIP Spacers as the building foundations are being modified in an effort to keep it from sinking.

San Francisco, officially known as the city and county of San Francisco, is the commercial, financial, and cultural centre of Northern California. The city is the 17th most populous in the United States and is known worldwide for its attractions such as the glittering red wonder of the Golden Gate Bridge from which travellers can look out upon the San Francisco Bay.

Once the ideal residential location, the 197 m Millennium Tower had sunk more than 45 cm.
Once the ideal residential location, the 197 m Millennium Tower had sunk more than 45 cm.

While most well recognised for the spooky allure of Alcatraz Island and the vibrant yet somewhat kitschy cable car system, San Francisco has an unfortunate issue affecting one of its very high-profile skyscrapers. 

As of March 2022, the 197 m Millennium Tower had sunk more than 45 cm. This has caused the tower to begin to lean 60 cm to the west and 20 cm north. Despite varied attempts to rectify the issue, the tower is continuing to tilt approximately 7 cm more north and 2 cm more west with each year.

Reportedly, if nothing is done to fix the issue the tower could reach a lean of more than a metre at which point the elevator and plumbing systems within the building would no longer function.

The place to live prior to it beginning to lean, the race is on to save the Millennium Tower.

Taking part in the fight to rectify the issue, Australia’s kwik-ZIP Spacers and Centralisers are getting in on the action.

kwik-ZIP is a well-known and respected brand within many industry sectors in the Australian, New Zealand, UK & USA markets including in production well drilling, trenchless pipeline, horizontal directional drilling (HDD) and the general civil and construction markets.

Manufactured from high grade engineering polymers, kwik-ZIP products are used and recommended by pipeline and civil contractors, water, and gas utilities, drilling companies and international engineering firms.

Engineers proposed and commenced the installation of 52 piles along the North and West sides of the 311,000-tonne building. These new piles are just over 76 m deep and reach to the bedrock under the building. 

The new piles would be tied to the existing piles (installed during the buildings construction) thus stabilising two sides of the building. The solution proposed involved leaving the building to settle further naturally and it was estimated that further settling of the South and East sides of the building over a period of 10 years would resolve about 50 per cent of the tilt. Once that correction had been achieved, additional piles would be added to the South and East sides and tied to the original piles to complete the rectification.  

kwik-ZIP HDX-125 spacers installed on 24-inch steel piles to San Francisco’s sinking Millennium Tower.
kwik-ZIP HDX-125 spacers installed on 24-inch steel piles to San Francisco’s sinking Millennium Tower.

kwik-ZIP spacers have been installed into the new piles to help centralise and facilitate the installation process. According to Anthony Lucido – Director of Foundations Operations – the spacers worked well and assisted with the pile installation process.  

The piles sunk into the ground were 24-inch OD steel pipes, installed into 36-inch OD steel casing with ¾-inch wall thickness. kwik-ZIP HDX-125 spacers provided the customer with the ability to centre the piles during installation and during the grouting process.

Modifications on the tower have not been completed as of this writing, because it was noted that the building had sunk a further inch on one side, during the installation of some of the piles. As the tower is now leaning at 29-inches at the top Northwest corner, planning is currently underway to provide further stabilisation so that the remaining new piles can be installed.       

While not a complete solution to the Millennium Tower’s tilt, kwik-ZIP’s spacers and centralisers have been an undeniable help in the reorientation of the once multi-million-dollar property listing. 

Massive buildings with low fault tolerances are built on compactable soil in locations across the globe with very few suffering from the problems that have plagued the Millennium Tower. It’s a testament not only to the engineers working to un-tilt the project as well as the infrastructure companies and manufacturers like kwik-ZIP that attempts can even be made to un-tilt a 197 m skyscraper.

For now, the fight to fix the tilt continues. 

For more information and to find out more about kwik-ZIP’s spacers and centralisers, visit the website.

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