It happened sometime between when crews closed up for the night around 8 p.m. Wednesday and when they returned Thursday morning.
Philadelphia police Det. Stephen Dewey says the vandals used a front-end loader and a bucket loader at the site to trash the crane, a huge generator, portable toilets and other things at the site.
The machinery, belonging to the Walsh Group, was also damaged. It was obvious to company officials that the vandals knew what they were doing.
"It is apparent to us that this is not neighborhood kids throwing rocks," said Aaron Tubbs of the Walsh Group. "These are people who know how to operate this equipment and are in, what we would say, 'the business.'"
The crews are doing work on sewer lines and storm drains.
"It's so disheartening, seeing the equipment worth millions of dollars destroyed. We're a union contractor, we're working two other projects Philly," said Nestor Martinez, General Supervisor for the Walsh Group. "We're all union, we hire from the halls. Why would somebody do something like this?"
Martinez went on to say this is the second time they've been hit. A few weeks ago, two bulldozers were damaged. One was flipped and one was almost driven into the river.
Total damage estimates are around $3.5 million, which will be covered by insurance.
Authorities say they didn't immediately have any suspects in the case.
The Citizens Crime Commission is administering a $10,000 reward posted by the Walsh Group for any information that would lead to the arrest and conviction of the individual(s) responsible for this vandalism.