San Francisco has succeeded in firing a subcontractor whose workers repeatedly breached natural gas lines and disrupted a major infrastructure project in the city's Haight neighborhood.

The company, Synergy Project Management, was also involved in several episodes that raised questions about its safety practices -- including one in which workers dangled a foreman head first into a Haight Street manhole.

Last Friday, a city administrative hearing officer rejected an appeal by Synergy months after San Francisco Public Works halted a $13.7 million job involving sewage replacement, street repaving and water main installations.

When the agency first tried to remove Synergy from the project, the company appealed, leading to a hearing in early December.

Firing a company working on a public works job is rare, the city says. "I'm not aware of this happening on a street excavation project [in the past]," Public Works spokeswoman Rachel Gordon said.

"It's about freakin' time," Board of Supervisors President London Breed, who represents the Haight, said in an email after learning of the hearing officer's decision.

Synergy's president reacted angrily to the city's move and said he's contemplating a lawsuit against the city and PG&E.

The company contends the repeated breaches of gas distribution lines -- five in all -- happened because PG&E had not provided accurate information about their locations.

"Synergy is being made a scapegoat for PG&E's inaccurate and incomplete information about where the gas lines are," Javad Mirsaidi said in an email to KQED. "It's not fair to blame Synergy for all of the problems on the job."

PG&E has disputed that claim.

Work on the Haight Street project began late last April. Two days into the work, Synergy employees hit a 2-inch plastic gas line at Haight Street and Masonic Avenue as they dug into the pavement. The resulting leak led the Fire Department to evacuate nearby businesses.

By early October, Synergy crews hit gas lines four more times, prompting street closures, shelter-in-place orders for local businesses and gas outages for some customers.

S.F. Public Works stopped work on the project in mid-September after the third gas leak and again after the fifth leak.

The hearing officer, Tim Leung, found that at least four of the leaks were the result of Synergy's unsafe practices.

Leung also found that the company "improperly shored trenches on multiple occasions, which could have led to street collapse, trench collapse, and the injury or death of workers or members to the public."

One incident, city officials said, put Synergy workers in grave danger.

That episode occurred around 8:30 p.m. last July 21, when Synergy employees decided they needed to remove a plug that had been left in a sewer line. Several company employees opened up a manhole at Haight and Pierce streets. Then two of them dangled a project foreman into the manhole by holding onto his ankles. That scene is shown in a picture provided to Public Works by Muni.

The incident took place just after sunset, and Public Works says workers didn't attempt to provide traffic control.

"That one incident was extremely disturbing on a number of fronts," department spokeswoman Gordon said.

Cal/OSHA did not investigate the incident because no one filed a complaint or referred the case, agency spokesman Julia Bernstein said in an email.

The state workplace regulator did cite Synergy last year when an employee was hurt in an incident involving an excavator at a project at Fourth and Harrison streets.  Cal/OSHA issued a $5,150 fine that's been appealed, Bernstein said.

Less than a week later a pedestrian slipped and fell on a forklift that Synergy left sitting on a wheelchair ramp at Haight Street and Buena Vista Avenue.

The main contractor on the project is Ghilotti Bros., a century-old firm based in San Rafael.

Michael Ghilotti, the company's president and co-owner, supported Synergy during the city's administrative hearing and argued that the city had no right to kick the subcontractor off the job and that the firm did its work exactly as the city instructed.

Ghilotti noted that the city must have been happy with the work because it made a progress payment to the company three days before it asked that Synergy be fired.

Synergy's Mirsaidi testified that his company provided extra training and safety communication to its workers. But he described the episode involving a worker being dangled inside a manhole as "unexcusable" and said he took full responsibility for the pedestrian tripping.

Mirsaidi says he believes the hearing officer, a city employee, was biased. Public Works spokeswoman Gordon describes the officer as "independent."

On Monday, the department sent a letter to Ghilotti Bros. asking the firm to submit a list of potential new subcontractors to replace Synergy by this Friday.

Gordon said the department wants the project restarted soon and emphasized the new subcontractor would need to follow stringent safety rules.

A spokeswoman for Ghilotti Bros. said the company has no comment at this time.

Public Works wants the rest of the industry to take notice of the firing. "Is it a message to the contracting community? It is indeed," Gordon said.

The hearing officer's decision comes as a Board of Supervisors committee prepares for a hearing looking into whether the city needs to do a better job of making sure underground work for public agencies is being done safely enough.

Supervisor Breed, who represents the district where the infrastructure project is taking place, called for the hearing before the Government Audit and Oversight Committee on Thursday.

Breed has asked Public Works, PG&E, Ghilotti Bros and Synergy, among others, to appear. Two Haight neighborhood groups are also expected to speak.

Breed said she called for the hearing because of worries from merchants and residents in her district stemming from the repeated gas leaks.

"People were concerned. They were scared and rightfully so," Breed said in an earlier interview.