Inspector Had Warned of Seismic Damage to Tank

Nine months before the rupture of a Westminster reservoir unleashed 5 million gallons of water into a neighborhood this week, an industrial inspector warned city officials that an earthquake might have damaged portions of the tank.

But instead of ordering a seismic study, the city ran the inspector’s findings by a second consultant, who dismissed them as “nothing to worry about.” The City Council eventually allocated $50,000 for a full seismic inspection when it approved its budget in June, though the project never occurred.

The rupture sent a 6-foot-high wall of water slamming into a quiet Westminster neighborhood Monday morning, flattening garages, injuring six people and damaging 49 homes.

The December 1997 study by the industrial inspector, Dive/Corr Inc., is the latest indication that city officials knew of problems with the reservoir well before the flood. On Monday, the former city manager said earlier reports found that the tank had developed cracks and was leaking.

Westminster hired Dive/Corr Inc. to examine the reservoir after officials discovered a fairly large leak, according to water superintendent Gary Heffelfinger.

The inspection, conducted by a diver, showed two rips in the liner, which the diver repaired, as well as rust, cracks and rotting caulking.

The inspector determined that although the majority of support beams were stable, a few beams displayed unusual “movement,” a term city and state officials used to describe damage caused by an earthquake. But the report didn’t find serious damage or recommend immediate action or repairs.

The findings were reviewed by city engineers and another consultant a month later, records show. The consultant, Gerry Emerson of Serrot Corp., concluded that “the existing condition is not serious. . . . We have nothing to worry about.”

City officials Tuesday defended their handling of the situation, noting that they were planning to conduct the type of seismic inspection suggested by Dive/Corr Inc. when the rupture occurred.

One councilwoman, Margie L. Rice, disputed allegations by former Mayor Charles V. Smith, now a county supervisor, earlier this week that city officials were well aware of damage to the tanks.

If Smith “had knowledge that city reservoirs were unsafe, other than in the event of an earthquake, he did not share it with other members of the Westminster City Council,” Rice said in a prepared statement.

City Engineer Marwan Youssef said that although a seismic study was necessary, there did not appear to be an immediate need to make improvements to the tank. He said the city had limited funds and had to balance several projects at once.

In a statement released Tuesday, city officials said that none of the findings in the December 1997 report “dealt with the structural integrity of the tank.”

But Cor Shaffer, a state engineer who inspects reservoirs for drinking water quality, said that Dive/Corr Inc.’s discovery of weakened support beams does raise questions about whether a portion of the tank was structurally sound.

The water tank that ruptured differs from most reservoirs in Orange County in that it was made of precast concrete--a building material that has proved unstable during major earthquakes.

Officials from more than a dozen local water districts interviewed Tuesday said their tanks are made from either steel or poured concrete, both of which are considered stronger and more stable than precast concrete.

“There are very few cities with similar tanks in the Southern California region,” said Ash Dhingra, vice president of Montgomery Watson, an environmental engineering firm in Pasadena. “This technology was formed in the 1960s, and technology has advanced quite a bit since then.”

Santa Ana still has one precast concrete tank left. The 5-million-gallon structure is 35 years old and is in a neighborhood off Bear Street near Anton Boulevard.

“We check on it weekly,” said Thom Coughran, the city’s water resources manager. “It does work fine, and we do take care of it. There’s no sense in trying to get rid of something that is functionally working and is sound.”

Santa Ana’s seven other tanks are made of either steel or poured concrete. Coughran said the city got rid of a second precast concrete tank three years ago because it had deteriorated. It was replaced with a more modern tank.

Precast concrete was a popular building material in the 1960s. The building method involves stitching together large, prefabricated concrete slabs and beams rather than pouring the concrete into forms to harden as a single structure. The process is usually cheaper than pouring concrete or using heavier material like steel.

Several recent earthquakes, including the 1994 Northridge temblor, caused major damage to structures that use precast construction. Several parking structures, office buildings and department stores had to be demolished because the concrete slabs cracked and buckled.

“In a major earthquake, the precast concrete is not considered as resilient and can be subject to failure,” said Sandra Sutphen, an earthquake safety expert and professor at Cal State Fullerton.

State law doesn’t require public water districts to conduct structural inspections of any types of reservoirs, including precast concrete tanks.

Westminster is hiring a consultant to determine exactly what caused the rupture and what role, if any, the precast materials played. Other water officials across the county said they will follow the investigation closely.

“Certainly there is concern,” said Karl Kemp, general manager of Mesa Consolidated Water District in Costa Mesa. “We want to learn what the conditions were that caused it so we can all learn from it.”

“I think everyone steps back,” added Mike Dunbar, general manager of South Coast Water District. “Certainly it’s a call to each agency to ask ourselves if we are doing enough. I think it’s a wake-up call to all of us to reassess and just be a little more observant.”

Contributing to this report were Times staff writer Tina Nguyen and correspondents John Canalis and Harrison Sheppard.

Inside the Ruptured Tank

Built in 1968, the precast concrete tank that ruptured Monday in Westminster used the theory of the arch dam to restrain 5 million gallons of water. A look inside the tank:

36 concrete columns

Source: City of Westminster

Graphics reporting by BRADY MacDONALD / Los Angeles Times