WORLD TRADE Center Memorial foundations contractor EE Cruz is worried that design changes could lead to delays on its $17M (£9M) contract to install 142 piles on the footprint of the twin towers.
Chief estimator of New Jerseybased EE Cruz Steve Molon said there were concerns that design changes might be ordered that would require foundation work to be started again.
'It's still a design-in-progress and construction is pushing design, ' Molon said of the contract, due to complete next spring.
'A lot of design issues aren't finalised and we are getting little revisions here and there? the last thing we want to do is build something that isn't in the final plan.' The work involves removing remaining concrete foundations of the underground levels of the twin towers and blasting the basement rock down to hard Manhattan schist. New concrete foundations will be installed.
Ground water is also being pumped out and new drainage pipes fitted.
'There is a layer of softer decomposing rock that we have to remove, ' he said. 'You don't have to go that far down to get to the stratum of very hard rock that will take the higher loads, ' said Molon. 'We expect to start pouring concrete for the foundations in the next month or two.
'Like many jobs it's been a slow start, but it's a very tough site. Access and site co-ordination is the biggest challenge. Site security is very stringent and coordination with other contractors is tough.
'Work on the foundations for the Freedom Tower started before us, so when we came in they had to move a lot of their stuff to accommodate us.' Work has also begun on the new station for the Path train line from New Jersey, and will soon start on a new road that will run alongside the site.
'We are liaising with a bunch of different contractors, all with different aspirations, ' said Molon.
lMolon was interviewed by NCE's sister magazine Ground Engineering. The full interview will be published in GE's October edition.