Updated

A concrete-testing laboratory faked results for a LaGuardia Airport control tower, the new Yankee Stadium, the Lincoln Tunnel and more than a dozen other projects around the city, creating thousands of phony reports for tests designed to make sure concrete was strong enough, prosecutors said Thursday.

American Standard Testing and Consulting Laboratories Inc., President Alan Fortich and five staffers pleaded not guilty to racketeering and other charges in the latest of a string of prosecutions of concrete-testing labs.

Fortich and the company "vehemently deny the allegations in the indictment, and we shall fight this case," said their lawyer, Richard R. Leff.

Prosecutors said they believed any safety concerns had been addressed by retesting, plus some upgrades in projects they wouldn't specify.

But the case spotlighted the stubborn presence of concerns about fraud in an industry important to the safety of a city of skyscrapers and subways, especially since prosecutors said ASTC's 12 years of fraud continued even after another major lab was indicted and city officials tightened oversight of concrete testing in the last three years.

"The volume of fabricated tests was egregious" in the ASTC case, netting the company millions of dollars for results "that were no more than worthless pieces of paper," Manhattan District Attorney Cyrus R. Vance Jr. said.

New Hyde Park, N.Y.-based ASTC, Fortich and the accused engineers, lab directors and inspector "regularly skipped vital safety tests and created false reports to create the impression that the tests were performed," an indictment said.

The buildings included Memorial Sloan-Kettering Cancer Center, the Javits Center convention venue, a Columbia University science building, the Port Authority Bus Terminal, the Intrepid Sea, Air & Space Museum, the forthcoming Second Avenue subway line and office and apartment buildings, according to the indictment.

"The projects that American Standard worked on were varied and touched every part of New York City life," assistant district attorney Diana Florence told a judge.

The city Buildings Department said Thursday there was no evidence of safety concerns in seven named properties under its jurisdiction. They include the stadium; officials have said it already was retested because of an earlier case against another concrete lab.

The city Metropolitan Transportation Authority, which oversees the subway system, has rechecked the concrete in its affected projects, and no safety or structural problems were found, said Michael Boxer, special counsel to the transit agency's inspector general.

Engineers generally design buildings to make sure they will be safe even if there are problems with some materials.

ASTC also is accused of falsifying credentials to get city licenses and to qualify for programs that give small and minority-owned businesses a leg up in bidding on big government projects. Fortich paid tens of thousands of dollars in kickbacks to another company to serve as a front for such work, prosecutors said, declining to name the other company.

The MTA said Thursday it was reviewing its procedures for screening such firms.

The earlier cases heightened concern about construction safety in the city, spurring new scrutiny of concrete testing and the labs licensed to do it. Among other measures, city Department of Buildings inspectors started conducting new spot checks on concrete testing procedures.

They have done 375 audits of testing work at construction sites and laboratories since 2010, prompting more than 550 violation notices for issues such as improper materials storage and equipment, the Buildings Department said Thursday. Staffers also independently test concrete to ensure labs are doing their work properly.

A spot check on ASTC figures in the case, prosecutors said, declining to be more specific. The Buildings Department said it denied ASTC's bid to renew its city license in 2009.

Many builders in New York City depend on independent laboratories to test the concrete that forms skyscrapers, subway tunnels and other key pieces of its infrastructure.

Under the city building code, a lab hired for a construction project is supposed to mix up batches of concrete formulas, or mix designs, and subject them to pressure until they break to make sure they can withstand the loads they need to.

ASTC provided bogus results not only for nearly 3,000 mix design tests but also for tests of actual concrete samples from construction sites, the prosecutors said.

Suspicious similarities in various ASTC test results raised red flags for investigators, city Department of Investigation Commissioner Rose Gill Hearn said.

Leff, the defense attorney, said the company's tests were done properly and the allegations were "more interpretive than anything else."

Fortich, 44, declined to comment after being released on $250,000 bond. His co-defendants were released without bail.

If convicted, the men each could face up to 25 years in prison.

The case grew out of an investigation into Testwell Laboratories Inc. Indeed, some site owners turned to ASTC after Testwell was indicted in 2008, prosecutors said.

Testwell's president and a vice president were convicted in February 2010 of faking concrete and steel strength test results for nearly 120 projects in and around the city, including ground zero's centerpiece skyscraper and the new Yankee Stadium. The president, V. Reddy Kancharla, was sentenced to up to 21 years in prison.

The company and executives said they didn't mean to cheat anyone.

In April 2010, Stallone Testing Laboratories Inc. and lab director William Bayer pleaded guilty to falsifying mix design results for the World Trade Center memorial, the LaGuardia Airport control tower and dozens of other buildings.

Bayer's case is expected to be closed without jail time or probation if he stays out of trouble for three years.

About 30 labs are licensed to test concrete in the city, the Buildings Department said.

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Jennifer Peltz can be reached at http://twitter.com/jennpeltz