SAN FRANCISCO (KPIX 5) – Neighbors in San Francisco are outraged after a mistake by a contractor damaged the roots of 10 trees in a North Beach park badly enough that they have to be removed.

According to city officials, the damaged roots have made the trees too unstable.

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Public Works said a contractor damaged the trees’ roots during the construction of a playground at Washington Square Park In North Beach.

Angry residents say the city needs to do a better job supervising its contractors.

While not much has changed in the park for the last 60 years, its playground recently had a major renovation.

Unfortunately, the renovation is coming at a huge cost that can’t be measured in dollars.

Ken Maley of the organization Friends of Washington Square is heartbroken. In a matter of days, 9 Canary Island pines and one olive tree that have stood on the corner of the park since the late 1950’s are coming down because they have become a safety hazard.

“It’s been so emotional for us, because these trees are landmarks to our square,” said Maley. “It’s unfortunate, but it’s not an accident. It’s negligence.”

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Maley blames the Department of Public Works for the lack of oversight on the playground renovation project. According to Rachel Gordon from the Department of Public Works, in an attempt to install benches, Treaty Construction used an excavator and hit a single root.

The workers switched to hand digging to prevent further damage, but that didn’t stop the problem.

DPW is calling all of this an unfortunate mistake.

“I’m not looking to really point fingers, but it shouldn’t have happened,” said Gordon. “We thought we had the protocol to prevent this from happening. That wasn’t followed.”

One of the protocols that wasn’t followed was to consult a city arborist.  Instead, Gordon said Treaty Construction called in its own expert. The end result were roots greater than two inches in diameter being cut. Photos show other roots that suffered extensive damage with ripped and shredded bark. Gordon said Treaty Construction failed to follow the rules.

“Under the construction contract, it also says that if any work was going to be done on the trees or to the trees — if you were going to cut the roots or anything else – that you need to get permission from the city arborist,” said Gordon. “That was not done.”

Treaty Construction will pay for the removal and replacement of the trees. DPW is looking into possible fines against the company.

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KPIX 5 reached out to Treaty construction. They did not want to make a comment.