Is Sutro Tower safe? Twin Peaks neighbors wonder

The Independent, March 24, 1998
(quoted with permission)

By Emily Soares


It's up to code, but expert panel thinks that's not enough

Citing inadequate local building codes, an expert panel reviewing Sutro Tower's structural stability last week urged the tower's operators to conduct an analysis of the tower using the most up-to-date technology.

When the Planning Commission unanimously approved a permit allowing Sutro Tower, Inc. to hang a 12-ton digital antenna addition on the tower last month, several commissioners said they would feel better about their approval of the proposal if a panel of independent enginners reexamined it and allayed community doubts as to the tower's stability.

In response, Sutro Tower officials agreed to ask the Department of Building Inspection to assemble a Structural Advisory Committee of specialists who would review tower specifications within three weeks.

After two days of testimony by Sutro representatives, Department of Building Inspection staff, and members of the public, the three-member committee found that the tower's antenna permit complied with the current building code.

But, the committee also found that, in light of persistent questions about how the tower has been mainteined and the fact that the 1995 building code is out of date with regard to seismic-safety findings, Sutro owners should conduct a ground-motion study, known as a dynamic analysis, on the tower, using the most up-to-date technology.

Geotechnical engineer Dr. Frank Rollo, one of the three members of the structural-analysis panel, said that while hebelieved the tower could carry an additional 20,000 pounds without movement or settling and that the the tower probably had the "strength to carry the big one," he and other panel members could not confirm the tower's condition without additional testing.

Formal motion disallowed

City attorney Ilene Dick and Department of Building Inspection engineer Hanson Tom told the panel that to make a formal motion urging a dynamic analysis would be out of the committee's scope of work, in that the committee is required to determine only whether the structure meets the city code. The panel then reluctantly agreed to write the Department of Building Inspection a letter voicing panel members' concerns.

Frustrated residents who live beneath the tower and have beenrequesting a dynamic analysis of the structure for six months told the committee that if their concerns were not submitted as a formal motion they would be easier for Sutro's owners to disregard.

Project lobbyist Debra Stein urged the committee to make its views known to Sutro Tower, Inc., privately because "if you put it in a motion, it raises a grievous precedent for other project sponsors."

Dick also advised the panel against passing a formal motion, arguing that it would be giving contrary determinations if it said the antenna permit complied with code but that additional tests should nonetheless be performed.

But committee members said the inadequacy of the existing codes had made such a determination necessary.

"We're unanimous in our feelings and beliefs in that we would like the director to meet with the applicants (to urge a dynamic analysis)," said Rollo.

"Because we're very restricted in our scope of work, (we) can only act on that scope, but we have other beliefs and feelings of what should be done in the future," Rollo said.

"Our problem is that codes are not up to current safety (data)," said committee chair Dr. Theodore Zautty.

Other structural experts agree, including Dr. Abolhassan Astaneh, a professor and steel structure consultant. Noting current findings on the safety of steel structures in earthquakes, Astaneh, in a letter read aloud by a resident during the hearing, stated that "code compliance does not guarantee structural safety."

Committee members said that they did not want to leave the hearing room without some assurance that dialogue between Sutro Tower, Inc. and the Department of Building Inspection regarding testing and inspection of the tower would continue.

Sutro Tower general manager Gene Zastrow said he would commit to giving the Department of Building Inspection "our full attention to try to ensure for our own good that we have a safe structure."

But whenZastrow was asked by Rollo if he would object to a formal motion regarding dynamic analysis, he said, "I have to object on the basis of legal advice I keep getting."

Residents' frustrations increase

Stein said that though the committee's findings were confusing, "the important thing to recognize" is that committee members found "the tower is code-compliant, can withstand any seismic event, and that there was no reason for the city to mandate a dynamic analysis."

Neighbors who interpreted the committee's finding differently were outraged about the outcome of the hearing.

"It was a joke in that three individual peer reviewers felt that Sutro Tower needed to be scrutinized more thoroughly and they were limited by the (department) from doing their job," said Twin Peaks resident Christine Linnenbach.

And residents say they are concerned about what appears to have been a private meeting between Department of Building Inspection staff and Sutro lobbyists during a hearing break.

"We question whether or not the interaction we saw between Department of Building Inspection staff, project sponsors, and the City Attorney's Office was ethical," said Linnenbach.

For Sutro Tower neighbors, the fight is not over. The next step, they say, is the Board of Supervisors, wehre community members will urge the board to decertify the tower's environmental impact report and require that a dynamic analysis be performed.

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