Montgomery County still hopes to begin repairs to the Silver Spring Transit Center some time next month, but may seek additional tests on the structure before work begins, the official overseeing the project said this week.

General Services Director David Dise said that concrete strength in the $120 million bus-and-train hub was still under study by Parsons Brinckerhoff, designer of the hub, and KCE, the consulting engineering firm that identified numerous construction and design flaws this spring.

“PB and KCE are continuing joint review and evaluation of in-place concrete strength,” Dise said in a June 10 letter to County Executive Isiah Leggett and Council President Nancy Navarro. “This may include new core testing to verify prior test results.”

Dise also said that ground-penetrating radar testing is underway on beams and slabs on the two upper levels of the three-tier facility to confirm areas with insufficient concrete cover. The county has used radar testing in the past to investigate deficiencies with concrete and supporting steel.

It was not clear from the letter who requested the additional tests. The Washington Metropolitan Area Transit Authority (WMATA), which is supposed to operate the facility when it opens, has expressed repeated concerns about its safety and durability and threatened to back away from its agreement with the county.

Concrete issues at the Silver Spring Transit Center

Dise did not return a phone message Friday afternoon. But in the letter he said: “PB and KCE continue to support WMATA’s technical concerns and request for more testing.”

The letter, which mentioned no scheduled opening date, was an update on the progress by contractors and county officials on repair efforts. The effort, known as the Silver Spring Transit Center Cooperative Remediation Working Group, was assembled this spring after a prolonged period of public fingerpointing over what went wrong with the project, which is more than two years and tens of millions of dollars over budget.

“There is continued cooperation by all parties,” Dise wrote.