Authorities Cringe as Va. Garage Crumbles

But county records and interviews reveal a series of checks and safeguards that fell short.

The county had a construction-materials testing lab of its own until it was closed in 1992 because of budget cuts. Since then, Fairfax has typically used outside quality-control consultants to oversee projects at various stages. But Concrete Structures was not monitored at first because its plant had been inspected and certified by an industry accrediting organization, the Chicago-based Precast/Prestressed Concrete Institute.

When cracks first appeared, the county retained Froehling and Robertson, a Richmond engineering firm, to observe the rest of Concrete Structure's work on the project. That included checking the content of the concrete mix for the proper level of what construction professionals call "air entrainment."

Because water expands when it freezes, tiny air bubbles are dispersed into the concrete mix, creating a system of pores to accommodate ice crystals and relieve pressure within the concrete. Without adequate air entrainment, concrete cracks and crumbles more easily. According to county records, Froehling and Robertson's tests, conducted between June 1997 and June 1998, showed the concrete with sufficient air content.

But when new cracks emerged last year, core samples of the concrete taken in April by Concorr, a Sterling testing firm, showed the air content to be "much lower than recommended."

Sam Kirby, president of Froehling and Robertson, said that he cannot specifically account for the decline in air content but that a number of other factors, including weather and maintenance, come into play.

Jenkins theorized that something added to the concrete might have had a destabilizing effect. In any event, he said, the county would not attempt to hold Froehling and Robertson, or any other party, legally responsible because of the difficulty in establishing the exact cause of the deterioration.

"It is also difficult for us to put together a complete and accurate picture of what happened back in 1997-98 with the precasted units," Jenkins said in an e-mail last week.

Hudgins said she was concerned about the level of oversight brought to project by outside consultants. "Anytime we outsource, we have to pull in the same level of due diligence," she said.

Jenkins said the county testing lab would not have detected the air entrainment issue.

Another red flag raised by Walker was the absence of certain steel connections within portions of the concrete. Ordinarily, the steel creates a "diaphragm action" that absorbs forces encountered during high winds or earthquakes. "Since diaphragm action is an essential design element we find it difficult to believe that such an important issue was not considered," Gregory J. Neiderer, Walker's lead engineer on the garage study, wrote to a county official in August.

The county asked the Consulting Engineers Group of San Antonio, the original design engineer on the project, to review its calculations. Walter Korkosz, the firm's president, told county officials in an e-mail that he was confident that the design, although different than the one described by Walker, was sound.