A random sample of payroll records at a Gaithersburg trash-hauling company has produced enough evidence to warrant a full-scale investigation into whether the firm is complying with the county’s “living wage” law, a Montgomery County official said Thursday evening.

The sampling was conducted after a three-day strike by workers at Potomac Disposal, a firm that has a $2.6 million contract with Montgomery for trash and recycling pickup in parts of Silver Spring, Bethesda, Rockville and Potomac. A 2003 County law requires that contractors pay their employees a “living wage” that is currently $13.95 per hour — nearly twice the federal minimum wage.

But a check of nine two-week pay periods for 11 helpers between April and June showed 23 instances in which their hourly rate was anywhere from one cent to $1.55 below the county requirement.

General Services Director David Dise said the sampling, conducted for the county by JDM Consulting of Burtonsville, was enough to justify a full payroll audit.

“We saw enough that gave us cause for concern,” Dise said.

The 57 mostly Latino drivers and helpers struck after alleging that the company threatened them with immigration enforcement in an attempt to leverage stalled contract talks. They also charged that many of them did not make the “living wage.”

If the broader probe shows consistent violation of the wage law, the company could be subject to civil penalties or termination of the contract.

Potomac Disposal president Lee Levine did not return a phone message.